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diff --git a/15707-h/15707-h.htm b/15707-h/15707-h.htm new file mode 100644 index 0000000..4872bda --- /dev/null +++ b/15707-h/15707-h.htm @@ -0,0 +1,21476 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> + +<html xmlns="http://www.w3.org/1999/xhtml"> + <head> + <meta http-equiv="Content-Type" content= + "text/html; charset=iso-8859-1" /> + <title> + Zoonomia, or the Laws of Organic Life. + </title> + + <style type="text/css"> + +<!-- + p { margin-top: .75em; + text-align: justify; + margin-bottom: .75em; + } + H1,H2,H3,H4,H5,H6 { + text-align: center; /* all headings centered */ + } + hr {text-align: center; width: 50%;} + hr.full {width: 100%;} + hr.short {text-align: center; width: 20%;} + body { margin-left: 10%; + margin-right: 10%; + } + + td.tbar { border-left : thin solid black; vertical-align: top; } + td.tc { padding-left: 1em; padding-right: 1em; text-align: center; vertical-align: top; } + td.mbar { border-left : thin solid black; vertical-align: middle; } + table.allb { border : thin solid black; border-collapse: collapse } + td.allb { border : thin solid black; padding-left: 1em; padding-right: 1em; } + .single p {margin: 0;} + + .contents + {margin-left:30%; margin-right:10%; margin-bottom: 1em; text-align: left;} + .contents .stanza {margin: 1em 0em 1em 0em;} + .contents p {margin: 0; padding-left: 3em; text-indent: -3em;} + + .poem + {margin-left:10%; margin-right:10%; margin-bottom: 1em; text-align: left;} + .poem .stanza {margin: 1em 0em 1em 0em;} + .poem p {margin: 0; padding-left: 3em; text-indent: -3em;} + p.i2 {margin-left: 1em;} + p.i4 {margin-left: 2em;} + p.i6 {margin-left: 3em;} + p.i8 {margin-left: 4em;} + p.z8 {margin-left: 4em; font-style: italic;} + p.i10 {margin-left: 5em;} + p.z10 {margin-left: 5em; font-style: italic;} + p.i12 {margin-left: 6em;} + p.i16 {margin-left: 8em;} + p.i20 {margin-left: 10em;} + + a:link {color:blue; text-decoration:underline} + a:visited {color:blue; text-decoration:underline} + a:hover {color:red} + link {color:blue; text-decoration:underline} + + .noflo + {margin-bottom: 1em; text-align: left;} + .noflo .stanza {margin: 1em 0em 1em 0em;} + .noflo p {margin: 0; padding-left: 3em; text-indent: -3em;} + .noflo p.i2 {margin-left: 1em;} + .noflo p.i16 {margin-left: 8em;} + + .author {text-align: right; margin-top: -1em; margin-right: 5%;} + .center {text-align: center; } + .right {text-align: right; } + .t {vertical-align: top; } + .tr {vertical-align: top;} + .tc {vertical-align: top;} + .tr p {text-align: right;} + .tc p {text-align: center;} + .m {vertical-align: middle; } + .mr {vertical-align: middle;} + .mc {vertical-align: middle;} + .mr p {text-align: right;} + .mc p {text-align: center;} + .b {vertical-align: bottom; } + .vol {/*font-weight: bold;*/ font-size: small;} + /* .grk {font-weight: bold; font-style: italic; } */ + .grk {font-style: normal; } + pre {font-family: "Courier New", Courier, monospace; margin-left: 1em; } + .linenum {position: absolute; top: auto; left: 60%;} /* poetry number */ + blockquote {margin-left: 2em; margin-right: 2em; } + blockquote.small {font-size: small; } + .pagenum {position: absolute; left: 92%; font-size: smaller; text-align: right;} /* page numbers */ + .sidenote {position: absolute; left: 92%; font-size: smaller; text-align: left;} /* sidenotes */ + .note {margin-left: 2em; margin-right: 2em; + font-size: small; } /* footnote */ + .sc {font-size: smaller; } /* small caps. */ + + .nobo {border: thin;} + .red {color: red;} + .figure, .figcenter, .figright, .figleft + {padding: 1em; margin: 0; text-align: center; font-size: 0.8em;} + .figure img, .figcenter img, .figright img, .figleft img + {border: none;} + .figure p, .figcenter p, .figright p, .figleft p + {margin: 0; text-indent: 1em;} + .figure p.in, .figcenter p.in, .figright p.in, .figleft p.in + {margin: 0; text-indent: 8em;} + .figcenter {margin: auto;} + .figright {float: right;} + .figleft {float: left;} + // --> + </style> + </head> +<body> + + +<pre> + +The Project Gutenberg EBook of Zoonomia, Vol. I, by Erasmus Darwin + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Zoonomia, Vol. I + Or, the Laws of Organic Life + +Author: Erasmus Darwin + +Release Date: April 25, 2005 [EBook #15707] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK ZOONOMIA, VOL. I *** + + + + +Produced by Greg Alethoup, Robert Shimmin, Keith Edkins and the +Online Distributed Proofreading Team. + + + + + + +</pre> + +<h1>ZOONOMIA;</h1> + +<p class="center" style="margin-top: 2em;">OR,</p> + +<h3>THE LAWS</h3> + +<p class="center" style="margin-top: 2em;">OF</p> + +<h2>ORGANIC LIFE.</h2> + +<h3>VOL. I.</h3> + +<h3><i>By ERASMUS DARWIN, M.D. F.R.S.</i></h3> + +<p class="center" style="margin-top: 2em;">AUTHOR OF THE BOTANIC GARDEN.</p> + + <br clear="all" /> +<hr /> + + <div class="contents"> + <div class="stanza"> + <p>Principiò cœlum, ac terras, camposque liquentes,</p> + <p>Lucentemque globum lunæ, titaniaque astra,</p> + <p>Spiritus intùs alit, totamque infusa per artus</p> + <p>Mens agitat molem, et magno se corpore miscet.—V<font class="sc">IRG</font>. Æn. vi.</p> + </div> + + <div class="stanza"> + <p>Earth, on whose lap a thousand nations tread,</p> + <p>And Ocean, brooding his prolific bed,</p> + <p>Night's changeful orb, blue pole, and silvery zones,</p> + <p>Where other worlds encircle other suns,</p> + <p>One Mind inhabits, one diffusive Soul</p> + <p>Wields the large limbs, and mingles with the whole.</p> + </div> + </div> + <br clear="all" /> +<hr /> + +<h3><i>THE SECOND EDITION, CORRECTED.</i></h3> + + <br clear="all" /> +<hr /> + +<p class="center" style="margin-top: 2em;">LONDON:<br /> +PRINTED FOR. J. JOHNSON, IN ST. PAUL'S CHURCH-YARD.<br /> +1796.</p> + +<h4>Entered at Stationers' Hall.</h4> + + <br clear="all" /> +<hr /> + +<h3>DEDICATION.</h3> + + <p>To the candid and ingenious Members of the College of Physicians, of + the Royal Philosophical Society, of the Two Universities, and to all + those, who study the Operations of the Mind as a Science, or who practice + Medicine as a Profession, the subsequent Work is, with great respect, + inscribed by the Author,</p> + + <p>DERBY, May 1, 1794.</p> + +<h3>CONTENTS.</h3> + + +<table width="100%" class="single" summary="Contents." title="Contents."> + <tr> + <td align="right" width="14%"> + </td> + <td align="left" width="85%"> + <i>Preface.</i> + </td> + </tr> + + <tr> + <td align="right"> + S<font class="sc">ECT</font>. <a href="#sect_I">I</a>. + </td> + <td align="left"> + <i>Of Motion.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_II">II</a>. + </td> + <td align="left"> + <i>Explanations and Definitions.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_III">III</a>. + </td> + <td align="left"> + <i>The Motions of the Retina demonstrated by Experiments.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_IV">IV</a>. + </td> + <td align="left"> + <i>Laws of Animal Causation.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_V">V</a>. + </td> + <td align="left"> + <i>Of the four Faculties or Motions of the Sensorium.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_VI">VI</a>. + </td> + <td align="left"> + <i>Of the four Classes of Fibrous Motions.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_VII">VII</a>. + </td> + <td align="left"> + <i>Of Irritative Motions.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_VIII">VIII</a>. + </td> + <td align="left"> + <i>Of Sensitive Motions.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_IX">IX</a>. + </td> + <td align="left"> + <i>Of Voluntary Motions.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_X">X</a>. + </td> + <td align="left"> + <i>Of Associate Motions.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XI">XI</a>. + </td> + <td align="left"> + <i>Additional Observations on the Sensorial Powers.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XII">XII</a>. + </td> + <td align="left"> + <i>Of Stimulus, Sensorial Exertion, and Fibrous Contraction.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XIII">XIII</a>. + </td> + <td align="left"> + <i>Of Vegetable Animation.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XIV">XIV</a>. + </td> + <td align="left"> + <i>Of the Production of Ideas.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XV">XV</a>. + </td> + <td align="left"> + <i>Of the Classes of Ideas.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XVI">XVI</a>. + </td> + <td align="left"> + <i>Of Instinct.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XVII">XVII</a>. + </td> + <td align="left"> + <i>The Catenation of Animal Motions.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XVIII">XVIII</a>. + </td> + <td align="left"> + <i>Of Sleep.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XIX">XIX</a>. + </td> + <td align="left"> + <i>Of Reverie.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XX">XX</a>. + </td> + <td align="left"> + <i>Of Vertigo.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXI">XXI</a>. + </td> + <td align="left"> + <i>Of Drunkenness.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXII">XXII</a>. + </td> + <td align="left"> + <i>Of Propensity to Motion. Repetition. Imitation.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXIII">XXIII</a>. + </td> + <td align="left"> + <i>Of the Circulatory System.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXIV">XXIV</a>. + </td> + <td align="left"> + <i>Of the Secretion of Saliva, and of Tears. And of the Lacrymal + Sack.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXV">XXV</a>. + </td> + <td align="left"> + <i>Of the Stomach and Intestines.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXVI">XXVI</a>. + </td> + <td align="left"> + <i>Of the Capillary Glands, and of the Membranes.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXVII">XXVII</a>. + </td> + <td align="left"> + <i>Of Hemorrhages.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXVIII">XXVIII</a>. + </td> + <td align="left"> + <i>The Paralysis of the Lacteals.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXIX">XXIX</a>. + </td> + <td align="left"> + <i>The Retrograde Motions of the Absorbent Vessels.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXX">XXX</a>. + </td> + <td align="left"> + <i>The Paralysis of the Liver.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXXI">XXXI</a>. + </td> + <td align="left"> + <i>Of Temperaments.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXXII">XXXII</a>. + </td> + <td align="left"> + <i>Diseases of Irritation.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXXIII">XXXIII</a>. + </td> + <td align="left"> + —— <i>of Sensation.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXXIV">XXXIV</a>. + </td> + <td align="left"> + —— <i>of Volition.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXXV">XXXV</a>. + </td> + <td align="left"> + —— <i>of Relation.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXXVI">XXXVI</a>. + </td> + <td align="left"> + <i>The Periods of Diseases.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXXVII">XXXVII</a>. + </td> + <td align="left"> + <i>Of Digestion, Secretion, Nutrition.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXXVIII">XXXVIII</a>. + </td> + <td align="left"> + <i>Of the Oxygenation of the Blood in the Lungs and Placenta.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XXXIX">XXXIX</a>. + </td> + <td align="left"> + <i>Of Generation.</i> + </td> + </tr> + + <tr> + <td align="right"> + <a href="#sect_XL">XL</a>. + </td> + <td align="left"> + <i>Of Ocular Spectra.</i> + </td> + </tr> +</table> + + <br clear="all" /> +<hr /> + +<p class="center" style="margin-top: 2em;">TO</p> + +<h3>ERASMUS DARWIN,</h3> + +<p class="center" style="margin-top: 2em;">ON HIS WORK INTITLED</p> + +<h2>ZOONOMIA,</h2> + +<h3><i>By DEWHURST BILSBORROW.</i></h3> + + <br clear="all" /> +<hr /> + + <div class="poem"> + <div class="stanza"> + <p>HAIL TO THE BARD! who sung, from Chaos hurl'd</p> + <p>How suns and planets form'd the whirling world;</p> + <p>How sphere on sphere Earth's hidden strata bend,</p> + <p>And caves of rock her central fires defend;</p> + <div class="linenum">5</div><p>Where gems new-born their twinkling eyes unfold,</p> + <p>And young ores shoot in arborescent gold.</p> + <p class="i2">How the fair Flower, by Zephyr woo'd, unfurls</p> + <p>Its panting leaves, and waves its azure curls;</p> + <p>Or spreads in gay undress its lucid form</p> + <div class="linenum">10</div><p>To meet the sun, and shuts it to the storm;</p> + <p>While in green veins impassion'd eddies move,</p> + <p>And Beauty kindles into life and love.</p> + <p class="i2">How the first embryon-fibre, sphere, or cube,</p> + <p>Lives in new forms,—a line,—a ring,—a tube;</p> + <div class="linenum">15</div><p>Closed in the womb with limbs unfinish'd laves,</p> + <p>Sips with rude mouth the salutary waves;</p> + <p>Seeks round its cell the sanguine streams, that pass,</p> + <p>And drinks with crimson gills the vital gas;</p> + <p>Weaves with soft threads the blue meandering vein,</p> + <div class="linenum">20</div><p>The heart's red concave, and the silver brain;</p> + <p>Leads the long nerve, expands the impatient sense,</p> + <p>And clothes in silken skin the nascent Ens.</p> + <p class="i2">Erewhile, emerging from its liquid bed,</p> + <p>It lifts in gelid air its nodding head;</p> + <div class="linenum">25</div><p>The lights first dawn with trembling eyelid hails,</p> + <p>With lungs untaught arrests the balmy gales;</p> + <p>Tries its new tongue in tones unknown, and hears</p> + <p>The strange vibrations with unpractised ears;</p> + <p>Seeks with spread hands the bosom's velvet orbs.</p> + <div class="linenum">30</div><p>With closing lips the milky fount absorbs;</p> + <p>And, as compress'd the dulcet streams distil,</p> + <p>Drinks warmth and fragrance from the living rill;—</p> + <p>Eyes with mute rapture every waving line,</p> + <p>Prints with adoring kiss the Paphian shrine,</p> + <div class="linenum">35</div><p>And learns erelong, the perfect form confess'd,</p> + <p>Ideal Beauty from its mother's breast.</p> + <p class="i2">Now in strong lines, with bolder tints design'd,</p> + <p>You sketch ideas, and portray the mind;</p> + <p>Teach how fine atoms of impinging light</p> + <div class="linenum">40</div><p>To ceaseless change the visual sense excite;</p> + <p>While the bright lens collects the rays, that swerve,</p> + <p>And bends their focus on the moving nerve.</p> + <p>How thoughts to thoughts are link'd with viewless chains,</p> + <p>Tribes leading tribes, and trains pursuing trains;</p> + <div class="linenum">45</div><p>With shadowy trident how Volition guides,</p> + <p>Surge after surge, his intellectual tides;</p> + <p>Or, Queen of Sleep, Imagination roves</p> + <p>With frantic Sorrows, or delirious Loves.</p> + <p class="i2">Go on, O F<font class="sc">RIEND</font>! explore with eagle-eye;</p> + <div class="linenum">50</div><p>Where wrapp'd in night retiring Causes lie:</p> + <p>Trace their slight bands, their secret haunts betray,</p> + <p>And give new wonders to the beam of day;</p> + <p>Till, link by link with step aspiring trod,</p> + <p>You climb from N<font class="sc">ATURE</font> to the throne of G<font class="sc">OD</font>.</p> + <div class="linenum">55</div><p>—So saw the Patriarch with admiring eyes</p> + <p>From earth to heaven a golden ladder rise;</p> + <p>Involv'd in clouds the mystic scale ascends,</p> + <p>And brutes and angels crowd the distant ends.</p> + </div> + </div> + <p>T<font class="sc">RIN</font>. C<font class="sc">OL</font>. C<font + class="sc">AMBRIDGE</font>, <i>Jan.</i> 1, 1794.</p> + + <br clear="all" /> +<hr /> + +<h4>REFERENCES TO THE WORK.</h4> + + <div class="contents"> + <div class="stanza"> + <p class="i8"><i>Botanic Garden.</i> Part I.</p> + </div> + + <div class="stanza"> + <p>Line 1. Canto I. l. 105.</p> + <p>—— 3. —— IV. l. 402.</p> + <p>—— 4. —— I. l. 140.</p> + <p>—— 5. —— III. l. 401.</p> + <p>—— 8. —— IV. l. 452.</p> + <p>—— 9. —— I. l. 14.</p> + </div> + + <div class="stanza"> + </div> + + <div class="stanza"> + <p class="i8"><i>Zoonomia.</i></p> + </div> + + <div class="stanza"> + <p>—— 12. Sect. <a href="#sect_XIII">XIII</a>.</p> + <p>—— 13. —— <a href="#sect_XXXIX_4_1">XXXIX. 4. 1</a>.</p> + <p>—— 18. —— <a href="#sect_XVI_2">XVI. 2</a>. and <a href="#sect_XXXVIII">XXXVIII</a>.</p> + <p>—— 26. —— <a href="#sect_XVI_4">XVI. 4</a>.</p> + <p>—— 30. —— <a href="#sect_XVI_4">XVI. 4</a>.</p> + <p>—— 36. —— <a href="#sect_XVI_6">XVI. 6</a>.</p> + <p>—— 38. —— <a href="#sect_III">III</a>. and <a href="#sect_VII">VII</a>.</p> + <p>—— 43. —— <a href="#sect_X">X</a>.</p> + <p>—— 44. —— <a href="#sect_XVIII_17">XVIII. 17</a>.</p> + <p>—— 45. —— <a href="#sect_XVII_3_7">XVII. 3. 7</a>.</p> + <p>—— 47. —— <a href="#sect_XVIII_8">XVIII. 8</a>.</p> + <p>—— 50. —— <a href="#sect_XXXIX_4_8">XXXIX. 4. 8</a>.</p> + <p>—— 51. —— <a href="#sect_XXXIX">XXXIX</a> the Motto.</p> + <p>—— 54. —— <a href="#sect_XXXIX_8">XXXIX. 8</a>.</p> + </div> + </div> + <br clear="all" /> +<hr /> + +<h2>PREFACE.</h2> + + <br clear="all" /> +<hr class="short" /> + + <p>The purport of the following pages is an endeavour to reduce the facts + belonging to A<font class="sc">NIMAL</font> L<font class="sc">IFE</font> + into classes, orders, genera, and species; and, by comparing them with + each other, to unravel the theory of diseases. It happened, perhaps + unfortunately for the inquirers into the knowledge of diseases, that + other sciences had received improvement previous to their own; whence, + instead of comparing the properties belonging to animated nature with + each other, they, idly ingenious, busied themselves in attempting to + explain the laws of life by those of mechanism and chemistry; they + considered the body as an hydraulic machine, and the fluids as passing + through a series of chemical changes, forgetting that animation was its + essential characteristic.</p> + + <p>The great C<font class="sc">REATOR</font> of all things has infinitely + diversified the works of his hands, but has at the same time stamped a + certain similitude on the features of nature, that demonstrates to us, + that <i>the whole is one family of one parent</i>. On this similitude is + founded all rational analogy; which, so long as it is concerned in + comparing the essential properties of bodies, leads us to many and + important discoveries; but when with licentious activity it links + together objects, otherwise discordant, by some fanciful similitude; it + may indeed collect ornaments for wit and poetry, but philosophy and truth + recoil from its combinations.</p> + + <p>The want of a theory, deduced from such strict analogy, to conduct the + practice of medicine is lamented by its professors; for, as a great + number of unconnected facts are difficult to be acquired, and to be + reasoned from, the art of medicine is in many instances less efficacious + under the direction of its wisest practitioners; and by that busy crowd, + who either boldly wade in darkness, or are led into endless error by the + glare of false theory, it is daily practised to the destruction of + thousands; add to this the unceasing injury which accrues to the public + by the perpetual advertisements of pretended nostrums; the minds of the + indolent become superstitiously fearful of diseases, which they do not + labour under; and thus become the daily prey of some crafty empyric.</p> + + <p>A theory founded upon nature, that should bind together the scattered + facts of medical knowledge, and converge into one point of view the laws + of organic life, would thus on many accounts contribute to the interest + of society. It would capacitate men of moderate abilities to practise the + art of healing with real advantage to the public; it would enable every + one of literary acquirements to distinguish the genuine disciples of + medicine from those of boastful effrontery, or of wily address; and would + teach mankind in some important situations the <i>knowledge of + themselves</i>.</p> + + <p>There are some modern practitioners, who declaim against medical + theory in general, not considering that to think is to theorize; and that + no one can direct a method of cure to a person labouring under disease + without thinking, that is, without theorizing; and happy therefore is the + patient, whose physician possesses the best theory.</p> + + <p>The words idea, perception, sensation, recollection, suggestion, and + association, are each of them used in this treatise in a more limited + sense than in the writers of metaphysic. The author was in doubt, whether + he should rather have substituted new words instead of them; but was at + length of opinion, that new definitions of words already in use would be + less burthensome to the memory of the reader.</p> + + <p>A great part of this work has lain by the writer above twenty years, + as some of his friends can testify: he had hoped by frequent revision 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 revising it; he therefore begs + of the candid reader to accept of it in its present state, and to excuse + any inaccuracies of expression, or of conclusion, into which the + intricacy of his subject, 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 treatise to be exempt.</p> + + <br clear="all" /> +<hr /> + +<h2>ZOONOMIA.</h2> + + <br clear="all" /> +<hr class="short" /> + +<h3>SECT. <a name="sect_I">I</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF MOTION.</p> + + <p>The whole of nature may be supposed to consist of two essences or + substances; one of which may be termed spirit, and the other matter. The + former of these possesses the power to commence or produce motion, and + the latter to receive and communicate it. So that motion, considered as a + cause, immediately precedes every effect; and, considered as an effect, + it immediately succeeds every cause.</p> + + <p>The <font class="sc">MOTIONS OF MATTER</font> may be divided into two + kinds, primary and secondary. The secondary motions are those, which are + given to or received from other matter in motion. Their laws have been + successfully investigated by philosophers in their treatises on mechanic + powers. These motions are distinguished by this circumstance, that the + velocity multiplied into the quantity of matter of the body acted upon is + equal to the velocity multiplied into the quantity of matter of the + acting body.</p> + + <p>The primary motions of matter may be divided into three classes, those + belonging to gravitation, to chemistry, and to life; and each class has + its peculiar laws. Though these three classes include the motions of + solid, liquid, and aerial bodies; there is nevertheless a fourth division + of motions; I mean those of the supposed ethereal fluids of magnetism, + electricity, heat, and light; whose properties are not so well + investigated as to be classed with sufficient accuracy.</p> + + <p><i>1st.</i> The gravitating motions include the annual and diurnal + rotation of the earth and planets, the flux and reflux of the ocean, the + descent of heavy bodies, and other phænomena of gravitation. The + unparalleled sagacity of the great N<font class="sc">EWTON</font> has + deduced the laws of this class of motions from the simple principle of + the general attraction of matter. These motions are distinguished by + their tendency to or from the centers of the sun or planets.</p> + + <p><i>2d.</i> The chemical class of motions includes all the various + appearances of chemistry. Many of the facts, which belong to these + branches of science, are nicely ascertained, and elegantly classed; but + their laws have not yet been developed from such simple principles as + those above-mentioned; though it is probable, that they depend on the + specific attractions belonging to the particles of bodies, or to the + difference of the quantity of attraction belonging to the sides and + angles of those particles. The chemical motions are distinguished by + their being generally attended with an evident decomposition or new + combination of the active materials.</p> + + <p><i>3d.</i> The third class includes all the motions of the animal and + vegetable world; as well those of the vessels, which circulate their + juices, and of the muscles, which perform their locomotion, as those of + the organs of sense, which constitute their ideas.</p> + + <p>This last class of motion is the subject of the following pages; + which, though conscious of their many imperfections, I hope may give some + pleasure to the patient reader, and contribute something to the knowledge + and to the cure of diseases.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_II">II</a>.</h3> + +<p class="center" style="margin-top: 2em;">EXPLANATIONS AND DEFINITIONS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_II_1">I</a>. <i>Outline of the animal + economy.</i>—<a href="#sect_II_2">II</a>. <a + href="#sect_II_2_1">1</a>. <i>Of the sensorium.</i> <a + href="#sect_II_2_2">2</a>. <i>Of the brain and nervous medulla.</i> <a + href="#sect_II_2_3">3</a>. <i>A nerve.</i> <a href="#sect_II_2_4">4</a>. + <i>A muscular fibre.</i> <a href="#sect_II_2_5">5</a>. <i>The immediate + organs of sense.</i> <a href="#sect_II_2_6">6</a>. <i>The external organs + of sense.</i> <a href="#sect_II_2_7">7</a>. <i>An idea or sensual + motion.</i> <a href="#sect_II_2_8">8</a>. <i>Perception.</i> <a + href="#sect_II_2_9">9</a>. <i>Sensation.</i> <a + href="#sect_II_2_10">10</a>. <i>Recollection and suggestion.</i> <a + href="#sect_II_2_11">11</a>. <i>Habit, causation, association, + catenation.</i> <a href="#sect_II_2_12">12</a>. <i>Reflex ideas.</i> <a + href="#sect_II_2_13">13</a>. <i>Stimulus defined.</i></p> + +</blockquote> + + <br clear="all" /> +<hr class="short" /> + +<blockquote class="b1"> + + <p>As some explanations and definitions will be necessary in the + prosecution of the work, the reader is troubled with them in this place, + and is intreated to keep them in his mind as he proceeds, and to take + them for granted, till an apt opportunity occurs to evince their truth; + to which I shall premise a very short outline of the animal economy.</p> + +</blockquote> + + <br clear="all" /> +<hr class="short" /> + + <p><a name="sect_II_1">I</a>.—<a name="sect_II_1_1">1</a>. The + nervous system has its origin from the brain, and is distributed to every + part of the body. Those nerves, which serve the senses, principally arise + from that part of the brain, which is lodged in the head; and those, + which serve the purposes of muscular motion, principally arise from that + part of the brain, which is lodged in the neck and back, and which is + erroneously called the spinal marrow. The ultimate fibrils of these + nerves terminate in the immediate organs of sense and muscular fibres, + and if a ligature be put on any part of their passage from the head or + spine, all motion and perception cease in the parts beneath the + ligature.</p> + + <p><a name="sect_II_1_2">2</a>. The longitudinal muscular fibres compose + the locomotive muscles, whose contractions move the bones of the limbs + and trunk, to which their extremities are attached. The annular or spiral + muscular fibres compose the vascular muscles, which constitute the + intestinal canal, the arteries, veins, glands, and absorbent vessels.</p> + + <p><a name="sect_II_1_3">3</a>. The immediate organs of sense, as the + retina of the eye, probably consist of moving fibrils, with a power of + contraction similar to that of the larger muscles above described.</p> + + <p><a name="sect_II_1_4">4</a>. The cellular membrane consists of cells, + which resemble those of a sponge, communicating with each other, and + connecting together all the other parts of the body.</p> + + <p><a name="sect_II_1_5">5</a>. The arterial system consists of the + aortal and the pulmonary artery, which are attended through their whole + course with their correspondent veins. The pulmonary artery receives the + blood from the right chamber of the heart, and carries it to the minute + extensive ramifications of the lungs, where it is exposed to the action + of the air on a surface equal to that of the whole external skin, through + the thin moist coats of those vessels, which are spread 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 scarlet. It is + then collected by the branches of the pulmonary vein, and conveyed to the + left chamber of the heart.</p> + + <p><a name="sect_II_1_6">6</a>. The aorta is another large artery, which + receives the blood from the left chamber of the heart, after it has been + thus aerated in the lungs, and conveys it by ascending and descending + branches to every other part of the system; the extremities of this + artery terminate either in glands, as the salivary glands, lacrymal + glands, &c. or in capillary vessels, which are probably less + involuted glands; in these some fluid, as saliva, tears, perspiration, + are separated from the blood; and the remainder of the blood is absorbed + or drank up by branches of veins correspondent to the branches of the + artery; which are furnished with valves to prevent its return; and is + thus carried back, after having again changed its colour to a dark red, + to the right chamber of the heart. The circulation of the blood in the + liver differs from this general system; for the veins which drink up the + refluent blood from those arteries, which are spread on the bowels and + mesentery, unite into a trunk in the liver, and form a kind of artery, + which is branched into the whole substance of the liver, and is called + the vena portarum; and from which the bile is separated by the numerous + hepatic glands, which constitute that viscus.</p> + + <p><a name="sect_II_1_7">7</a>. The glands may be divided into three + systems, the convoluted glands, such as those above described, which + separate bile, tears, saliva, &c. Secondly, the glands without + convolution, as the capillary vessels, which unite the terminations of + the arteries and veins; and separate both the mucus, which lubricates the + cellular membrane, and the perspirable matter, which preserves the skin + moist and flexible. And thirdly, the whole absorbent system, consisting + of the lacteals, which open their mouths into the stomach and intestines, + and of the lymphatics, which open their mouths on the external surface of + the body, and on the internal linings of all the cells of the cellular + membrane, and other cavities of the body.</p> + + <p>These lacteal and lymphatic vessels are furnished with numerous valves + to prevent the return of the fluids, which they absorb, and terminate in + glands, called lymphatic glands, and may hence be considered as long + necks or mouths belonging to these glands. To these they convey the chyle + and mucus, with a part of the perspirable matter, and atmospheric + moisture; all which, after having passed through these glands, and having + suffered some change in them, are carried forward into the blood, and + supply perpetual nourishment to the system, or replace its hourly + waste.</p> + + <p><a name="sect_II_1_8">8</a>. The stomach and intestinal canal have a + constant vermicular motion, which carries forwards their contents, after + the lacteals have drank up the chyle from them; and which is excited into + action by the stimulus of the aliment we swallow, but which becomes + occasionally inverted or retrograde, as in vomiting, and in the iliac + passion.</p> + + <p><a name="sect_II_2">II</a>. <a name="sect_II_2_1">1</a>. The word + <i>sensorium</i> in the following pages is designed to express not only + the medullary part of the brain, spinal marrow, nerves, organs of sense, + and of the muscles; but also at the same time that living principle, or + spirit of animation, which resides throughout the body, without being + cognizable to our senses, except by its effects. The changes which + occasionally take place in the sensorium, as during the exertions of + volition, or the sensations of pleasure or pain, are termed <i>sensorial + motions</i>.</p> + + <p><a name="sect_II_2_2">2</a>. The similarity of the texture of the + brain to that of the pancreas, and some other glands of the body, has + induced the inquirers into this subject to believe, that a fluid, perhaps + much more subtile than the electric aura, is separated from the blood by + that organ for the purposes of motion and sensation. When we recollect, + that the electric fluid itself is actually accumulated and given out + voluntarily by the torpedo and the gymnotus electricus, that an electric + shock will frequently stimulate into motion a paralytic limb, and lastly + that it needs no perceptible tubes to convey it, this opinion seems not + without probability; and the singular figure of the brain and nervous + system seems well adapted to distribute it over every part of the + body.</p> + + <p>For the medullary substance of the brain not only occupies the + cavities of the head and spine, but passes along the innumerable + ramifications of the nerves to the various muscles and organs of sense. + In these it lays aside its coverings, and is intermixed with the slender + fibres, which constitute those muscles and organs of sense. Thus all + these distant ramifications of the sensorium are united at one of their + extremities, that is, in the head and spine; and thus these central parts + of the sensorium constitute a communication between all the organs of + sense and muscles.</p> + + <p><a name="sect_II_2_3">3</a>. A <i>nerve</i> is a continuation of the + medullary substance of the brain from the head or spine towards the other + parts of the body, wrapped in its proper membrane.</p> + + <p><a name="sect_II_2_4">4</a>. The <i>muscular fibres</i> are moving + organs intermixed with that medullary substance, which is continued along + the nerves, as mentioned above. They are indued with the power of + contraction, and are again elongated either by antagonist muscles, by + circulating fluids, or by elastic ligaments. So the muscles on one side + of the forearm bend the fingers by means of their tendons, and those on + the other side of the fore-arm extend them again. The arteries are + distended by the circulating blood; and in the necks of quadrupeds there + is a strong elastic ligament, which assists the muscles, which elevate + the head, to keep it in its horizontal position, and to raise it after it + has been depressed.</p> + + <p><a name="sect_II_2_5">5</a>. The <i>immediate organs of sense</i> + consist in like manner of moving fibres enveloped in the medullary + substance above mentioned; and are erroneously supposed to be simply an + expansion of the nervous medulla, as the retina of the eye, and the rete + mucosum of the skin, which are the immediate organs of vision, and of + touch. Hence when we speak of the contractions of the fibrous parts of + the body, we shall mean both the contractions of the muscles, and those + of the immediate organs of sense. These <i>fibrous motions</i> are thus + distinguished from the <i>sensorial motions</i> above mentioned.</p> + + <p><a name="sect_II_2_6">6</a>. The <i>external organs</i> of sense are + the coverings of the immediate organs of sense, and are mechanically + adapted for the reception or transmission 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.</p> + + <p><a name="sect_II_2_7">7</a>. The word <i>idea</i> has various meanings + in the writers of metaphysic: it is here used simply for those notions of + external things, which our organs of sense bring us acquainted with + originally; and is defined a contraction, or motion, or configuration, of + the fibres, which constitute the immediate organ of sense; which will be + explained at large in another part of the work. Synonymous with the word + idea, we shall sometimes use the words <i>sensual motion</i> in + contradistinction to <i>muscular motion</i>.</p> + + <p><a name="sect_II_2_8">8</a>. The word <i>perception</i> includes both + the action of the organ of sense in consequence of the impact of external + objects, and our attention to that action; that is, it expresses both the + motion of the organ of sense, or idea, and the pain or pleasure that + succeeds or accompanies it.</p> + + <p><a name="sect_II_2_9">9</a>. The pleasure or pain which necessarily + accompanies all those perceptions or ideas which we attend to, either + gradually subsides, or is succeeded by other fibrous motions. In the + latter case it is termed <i>sensation</i>, as explained in Sect. <a + href="#sect_V_2">V. 2</a>, and <a href="#sect_VI_2">VI. 2</a>.—The + reader is intreated to keep this in his mind, that through all this + treatise the word sensation is used to express pleasure or pain only in + its active state, by whatever means it is introduced into the system, + without any reference to the stimulation of external objects.</p> + + <p><a name="sect_II_2_10">10</a>. The vulgar use of the word + <i>memory</i> is too unlimited for our purpose: those ideas which we + voluntarily recall are here termed ideas of <i>recollection</i>, as when + we will to repeat the alphabet backwards. And those ideas which are + suggested to us by preceding ideas are here termed ideas of + <i>suggestion</i>, as whilst we repeat the alphabet in the usual order; + when by habits previously acquired B is suggested by A, and C by B, + without any effort of deliberation.</p> + + <p><a name="sect_II_2_11">11</a>. The word <i>association</i> properly + signifies a society or convention of things in some respects similar to + each other. We never say in common language, that the effect is + associated with the cause, though they necessarily accompany or succeed + each other. Thus the contractions of our muscles and organs of sense may + be said to be associated together, but cannot with propriety be said to + be associated with irritations, or with volition, or with sensation; + because they are caused by them, as mentioned in Sect. <a + href="#sect_IV">IV</a>. When fibrous contractions succeed other fibrous + contractions, the connection is termed <i>association</i>; when fibrous + contractions succeed sensorial motions, the connection is termed + <i>causation</i>; when fibrous and sensorial motions reciprocally + introduce each other in progressive trains or tribes, it is termed + <i>catenation</i> of animal motions. All these connections are said to be + produced by <i>habit</i>; that is, by frequent repetition.</p> + + <p><a name="sect_II_2_12">12</a>. It may be proper to observe, that by + the unavoidable idiom of our language the ideas of perception, of + recollection, or of imagination, in the plural number signify the ideas + belonging to perception, to recollection, or to imagination; whilst the + idea of perception, of recollection, or of imagination, in the singular + number is used for what is termed "a reflex idea of any of those + operations of the sensorium."</p> + + <p><a name="sect_II_2_13">13</a>. By the word <i>stimulus</i> is not only + meant the application of external bodies to our organs of sense and + muscular fibres, which excites into action the sensorial power termed + irritation; but also pleasure or pain, when they excite into action the + sensorial power termed sensation; and desire or aversion, when they + excite into action the power of volition; and lastly, the fibrous + contractions which precede association; as is further explained in Sect. + <a href="#sect_XII_2_1">XII. 2. 1</a>.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_III">III</a>.</h3> + +<p class="center" style="margin-top: 2em;">THE MOTIONS OF THE RETINA DEMONSTRATED BY EXPERIMENTS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_III_1">I</a>. <i>Of animal motions and of ideas.</i> <a + href="#sect_III_2">II</a>. <i>The fibrous structure of the retina.</i> <a + href="#sect_III_3">III</a>. <i>The activity of the retina in vision.</i> + <a href="#sect_III_3_1">1</a>. <i>Rays of light have no momentum.</i> <a + href="#sect_III_3_2">2</a>. <i>Objects long viewed become fainter.</i> <a + href="#sect_III_3_3">3</a>. <i>Spectra of black objects become + luminous.</i> <a href="#sect_III_3_4">4</a>. <i>Varying spectra from + gyration.</i> <a href="#sect_III_3_5">5</a>. <i>From long inspection of + various colours.</i> <a href="#sect_III_4">IV</a>. <i>Motions of the + organs of sense constitute ideas.</i> <a href="#sect_III_4_1">1</a>. + <i>Light from pressing the eye-ball, and sound from the pulsation of the + carotid artery.</i> <a href="#sect_III_4_2">2</a>. <i>Ideas in sleep + mistaken for perceptions.</i> <a href="#sect_III_4_3">3</a>. <i>Ideas of + imagination produce pain and sickness like sensations.</i> <a + href="#sect_III_4_4">4</a>. <i>When the organ of sense is destroyed, the + ideas belonging to that sense perish.</i> <a href="#sect_III_5">V</a>. + <i>Analogy between muscular motions and sensual motions, or ideas.</i> <a + href="#sect_III_5_1">1</a>. <i>They are both originally excited by + irritations.</i> <a href="#sect_III_5_2">2</a>. <i>And associated + together in the same manner.</i> <a href="#sect_III_5_3">3</a>. <i>Both + act in nearly the same times.</i> <a href="#sect_III_5_4">4</a>. <i>Are + alike strengthened or fatigued by exercise.</i> <a + href="#sect_III_5_5">5</a>. <i>Are alike painful from inflammation.</i> + <a href="#sect_III_5_6">6</a>. <i>Are alike benumbed by compression.</i> + <a href="#sect_III_5_7">7</a>. <i>Are alike liable to paralysis.</i> <a + href="#sect_III_5_8">8</a>. <i>To convulsion.</i> <a + href="#sect_III_5_9">9</a>. <i>To the influence of old age.</i>—<a + href="#sect_III_6">VI</a>. <i>Objections answered.</i> <a + href="#sect_III_6_1">1</a>. <i>Why we cannot invent new ideas.</i> <a + href="#sect_III_6_2">2</a>. <i>If ideas resemble external objects.</i> <a + href="#sect_III_6_3">3</a>. <i>Of the imagined sensation in an amputated + limb.</i> <a href="#sect_III_6_4">4</a>. <i>Abstract ideas.</i>—<a + href="#sect_III_7">VII</a>. <i>What are ideas, if they are not animal + motions?</i></p> + +</blockquote> + + <p>Before the great variety of animal motions can be duly arranged into + natural classes and orders, it is necessary to smooth the way to this yet + unconquered field of science, by removing some obstacles which thwart our + passage. <a name="sect_III_1">I</a>. To demonstrate that the retina and + other immediate organs of sense possess a power of motion, and that these + motions constitute our ideas, according to the fifth and seventh of the + preceding assertions, claims our first attention.</p> + + <p>Animal motions are distinguished from the communicated motions, + mentioned in the first section, as they have no mechanical proportion to + their cause; for the goad of a spur on the skin of a horse shall induce + him to move a load of hay. They differ from the gravitating motions there + mentioned as they are exerted with equal facility in all directions, and + they differ from the chemical class of motions, because no apparent + decompositions or new combinations are produced in the moving + materials.</p> + + <p>Hence, when we say animal motion is excited by irritation, we do not + mean that the motion bears any proportion to the mechanical impulse of + the stimulus; nor that it is affected by the general gravitation of the + two bodies; nor by their chemical properties, but solely that certain + animal fibres are excited into action by something external to the moving + organ.</p> + + <p>In this sense the stimulus of the blood produces the contractions of + the heart; and the substances we take into our stomach and bowels + stimulate them to perform their necessary functions. The rays of light + excite the retina into animal motion by their stimulus; at the same time + that those rays of light themselves are physically converged to a focus + by the inactive humours of the eye. The vibrations of the air stimulate + the auditory nerve into animal action; while it is probable that the + tympanum of the ear at the same time undergoes a mechanical + vibration.</p> + + <p>To render this circumstance more easy to be comprehended, <i>motion + may be defined to be a variation of figure</i>; for the whole universe + may be considered as one thing possessing a certain figure; the motions + of any of its parts are a variation of this figure of the whole: this + definition of motion will be further explained in Section <a + href="#sect_XIV_2_2">XIV. 2. 2</a>. on the production of ideas.</p> + + <p>Now the motions of an organ of sense are a succession of + configurations of that organ; these configurations succeed each other + quicker or slower; and whatever configuration of this organ of sense, + that is, whatever portion of the motion of it is, or has usually been, + attended to, constitutes an idea. Hence the configuration is not to be + considered as an effect of the motion of the organ, but rather as a part + or temporary termination of it; and that, whether a pause succeeds it, or + a new configuration immediately takes place. Thus when a succession of + moving objects are presented to our view, the ideas of trumpets, horns, + lords and ladies, trains and canopies, are configurations, that is, parts + or links of the successive motions of the organ of vision.</p> + + <div class="figright" style="width:25%;"> + <a href="images/plateI.png"><img width="100%" src="images/plateI.png" + alt="Plate I." /></a> + Plate I. + </div> + <p>These motions or configurations of the organs of sense differ from the + sensorial motions to be described hereafter, as they appear to be simply + contractions of the fibrous extremities of those organs, and in that + respect exactly resemble the motions or contractions of the larger + muscles, as appears from the following experiment. Place a circular piece + of red silk about an inch in diameter on a sheet of white paper in a + strong light, as in Plate I.—look for a minute on this area, or + till the eye becomes somewhat fatigued, and then, gently closing your + eyes, and shading them with your hand, a circular green area of the same + apparent diameter becomes visible in the closed eye. This green area is + the colour reverse to the red area, which had been previously inspected, + as explained in the experiments on ocular spectra at the end of the work, + and in Botanical Garden, P. 1. additional note, No. 1. Hence it appears, + that a part of the retina, which had been fatigued by contraction in one + direction, relieves itself by exerting the antagonist fibres, and + producing a contraction in an opposite direction, as is common in the + exertions of our muscles. Thus when we are tired with long action of our + arms in one direction, as in holding a bridle on a journey, we + occasionally throw them into an opposite position to relieve the fatigued + muscles.</p> + + <p>Mr. Locke has defined an idea to be "whatever is present to the mind;" + but this would include the exertions of volition, and the sensations of + pleasure and pain, as well as those operations of our system, which + acquaint us with external objects; and is therefore too unlimited for our + purpose. Mr. Lock seems to have fallen into a further error, by + conceiving, that the mind could form a general or abstract idea by its + own operation, which was the copy of no particular perception; as of a + triangle in general, that was neither acute, obtuse, nor right angled. + The ingenious Dr. Berkley and Mr. Hume have demonstrated, that such + general ideas have no existence in nature, not even in the mind of their + celebrated inventor. We shall therefore take for granted at present, that + our recollection or imagination of external objects consists of a partial + repetition of the perceptions, which were excited by those external + objects, at the time we became acquainted with them; and that our reflex + ideas of the operations of our minds are partial repetitions of those + operations.</p> + + <p><a name="sect_III_2">II</a>. The following article evinces that the + organ of vision consists of a fibrous part as well as of the nervous + medulla, like other white muscles; and hence, as it resembles the + muscular parts of the body in its structure, we may conclude, that it + must resemble them in possessing a power of being excited into animal + motion.—The subsequent experiments on the optic nerve, and on the + colours remaining in the eye, are copied from a paper on ocular spectra + published in the seventy-sixth volume of the Philos. Trans. by Dr. R. + Darwin of Shrewsbury; which, as I shall have frequent occasion to refer + to, is reprinted in this work, Sect. <a href="#sect_XL">XL</a>. The + retina of an ox's eye was suspended in a glass of warm water, and + forcibly torn in a few places; the edges of these parts appeared jagged + and hairy, and did not contract and become smooth like simple mucus, when + it is distended till it breaks; which evinced that it consisted of + fibres. This fibrous construction became still more distinct to the light + by adding some caustic alcali to the water; as the adhering mucus was + first eroded, and the hair-like fibres remained floating in the vessel. + Nor does the degree of transparency of the retina invalidate this + evidence of its fibrous structure, since Leeuwenhoek has shewn, that the + crystalline humour itself consists of fibres. Arc. Nat. V. I. 70.</p> + + <p>Hence it appears, that as the muscles consist of larger fibres + intermixed with a smaller quantity of nervous medulla, the organ of + vision consists of a greater quantity of nervous medulla intermixed with + smaller fibres. It is probable that the locomotive muscles of microscopic + animals may have greater tenuity than these of the retina; and there is + reason to conclude from analogy, that the other immediate organs of + sense, as the portio mollis of the auditory nerve, and the rete mucosum + of the skin, possess a similarity of structure with the retina, and a + similar power of being excited into animal motion.</p> + + <p><a name="sect_III_3">III</a>. The subsequent articles shew, that + neither mechanical impressions, nor chemical combinations of light, but + that the animal activity of the retina constitutes vision.</p> + + <p><a name="sect_III_3_1">1</a>. Much has been conjectured by + philosophers about the momentum of the rays of light; to subject this to + experiment a very light horizontal balance was constructed by Mr. Michel, + with about an inch square of thin leaf-copper suspended at each end of + it, as described in Dr. Priestley's History of Light and Colours. The + focus of a very large convex mirror was thrown by Dr. Powel, in his + lectures on experimental philosophy, in my presence, on one wing of this + delicate balance, and it receded from the light; thrown on the other + wing, it approached towards the light, and this repeatedly; so that no + sensible impulse could be observed, but what might well be ascribed to + the ascent of heated air.</p> + + <p>Whence it is reasonable to conclude, that the light of the day must be + much too weak in its dilute state to make any mechanical impression on so + tenacious a substance as the retina of the eye.—Add to this, that + as the retina is nearly transparent, it could therefore make less + resistance to the mechanical impulse of light; which, according, to the + observations related by Mr. Melvil in the Edinburgh Literary Essays, only + communicates heat, and should therefore only communicate momentum, where + it is obstructed, reflected, or refracted.—From whence also may be + collected the final cause of this degree of transparency of the retina, + viz. left by the focus of stronger lights, heat and pain should have been + produced in the retina, instead of that stimulus which excites it into + animal motion.</p> + + <p><a name="sect_III_3_2">2</a>. On looking long on an area of scarlet + silk of about an inch in diameter laid on white paper, as in Plate I. the + scarlet colour becomes fainter, till at length it entirely vanishes, + though the eye is kept uniformly and steadily upon it. Now if the change + or motion of the retina was a mechanical impression, or a chemical tinge + of coloured light, the perception would every minute become stronger and + stronger,—whereas in this experiment it becomes every instant + weaker and weaker. The same circumstance obtains in the continued + application of sound, or of sapid bodies, or of odorous ones, or of + tangible ones, to their adapted organs of sense.</p> + + <div class="figright" style="width:25%;"> + <a href="images/plateII.png"><img width="100%" src="images/plateII.png" + alt="Plate II." /></a> + Plate II. + </div> + <p>Thus when a circular coin, as a shilling, is pressed on the palm of + the hand, the sense of touch is mechanically compressed; but it is the + stimulus of this pressure that excites the organ of touch into animal + action, which constitutes the perception of hardness and of figure; for + in some minutes the perception ceases, though the mechanical pressure of + the object remains.</p> + + <p><a name="sect_III_3_3">3</a>. Make with ink on white paper a very + black spot about half an inch in diameter, with a tail about an inch in + length, so as to resemble a tadpole, as in Plate II.; look steadfastly + for a minute on the center of this spot, and, on moving the eye a little, + the figure of the tadpole will be seen on the white part of the paper; + which figure of the tadpole will appear more luminous than the other part + of the white paper; which can only be explained by supposing that a part + of the retina, on which the tadpole was delineated, to have become more + sensible to light than the other parts of it, which were exposed to the + white paper; and not from any idea of mechanical impression or chemical + combination of light with the retina.</p> + + <p><a name="sect_III_3_4">4</a>. When any one turns round rapidly, till + he becomes dizzy, and falls upon the ground, the spectra of the ambient + objects continue to present themselves in rotation, and he seems to + behold the objects still in motion. Now if these spectra were impressions + on a passive organ, they either must continue as they were received last, + or not continue at all.</p> + + <p><a name="sect_III_3_5">5</a>. Place a piece of red silk about an inch + in diameter on a sheet of white paper in a strong light, as in Plate I; + look steadily upon it from the distance of about half a yard for a + minute; then closing your eye-lids, cover them with your hands and + handkerchief, and a green spectrum will be seen in your eyes resembling + in form the piece of red silk. After some seconds of time the spectrum + will disappear, and in a few more seconds will reappear; and thus + alternately three or four times, if the experiment be well made, till at + length it vanishes entirely.</p> + + <div class="figright" style="width:25%;"> + <a href="images/plateIII.png"><img width="100%" src="images/plateIII.png" + alt="Plate III." /></a> + Plate III. + </div> + <p><a name="sect_III_3_6">6</a>. Place a circular piece of white paper, + about four inches in diameter, in the sunshine, cover the center of this + with a circular piece of black silk, about three inches in diameter; and + the center of the black silk with a circle of pink silk, about two inches + in diameter; and the center of the pink silk with a circle of yellow + silk, about one inch in diameter; and the center of this with a circle of + blue silk, about half an inch in diameter; make a small spot with ink in + the center of the blue silk, as in Plate III.; look steadily for a minute + on this central spot, and then closing your eyes, and applying your hand + at about an inch distance before them, so as to prevent too much or too + little light from passing through the eye-lids, and you will see the most + beautiful circles of colours that imagination can conceive; which are + most resembled by the colours occasioned by pouring a drop or two of oil + on a still lake in a bright day. But these circular irises of colours are + not only different from the colours of the silks above mentioned, but are + at the same time perpetually changing as long as they exist.</p> + + <p>From all these experiments it appears, that these spectra in the eye + are not owing to the mechanical impulse of light impressed on the retina; + nor to its chemical combination with that organ; nor to the absorption + and emission of light, as is supposed, perhaps erroneously, to take place + in calcined shells and other phosphorescent bodies, after having been + exposed to the light: for in all these cases the spectra in the eye + should either remain of the same colour, or gradually decay, when the + object is withdrawn; and neither their evanescence during the presence of + their object, as in the second experiment, nor their change from dark to + luminous, as in the third experiment, nor their rotation, as in the + fourth experiment, nor the alternate presence and evanescence of them, as + in the fifth experiment, nor the perpetual change of colours of them, as + in the last experiment, could exist.</p> + + <p><a name="sect_III_4">IV</a>. The subsequent articles shew, that these + animal motions or configurations of our organs of sense constitute our + ideas.</p> + + <p><a name="sect_III_4_1">1</a>. If any one in the dark presses the ball + of his eye, by applying his finger to the external corner of it, a + luminous appearance is observed; and by a smart stroke on the eye great + slashes of fire are perceived. (Newton's Optics.) So that when the + arteries, that are near the auditory nerve, make stronger pulsations than + usual, as in some fevers, an undulating sound is excited in the ears. + Hence it is not the presence of the light and sound, but the motions of + the organ, that are immediately necessary to constitute the perception or + idea of light and sound.</p> + + <p><a name="sect_III_4_2">2</a>. During the time of sleep, or in + delirium, the ideas of imagination are mistaken for the perceptions of + external objects; whence it appears, that these ideas of imagination, are + no other than a reiteration of those motions of the organs of sense, + which were originally excited by the stimulus of external objects: and in + our waking hours the simple ideas, that we call up by recollection or by + imagination, as the colour of red, or the smell of a rose, are exact + resemblances of the same simple ideas from perception; and in consequence + must be a repetition of those very motions.</p> + + <p><a name="sect_III_4_3">3</a>. The disagreeable sensation called the + tooth-edge is originally excited by the painful jarring of the teeth in + biting the edge of the glass, or porcelain cup, in which our food was + given us in our infancy, as is further explained in the Section <a + href="#sect_XVI_10">XVI. 10</a>, on Instinct.—This disagreeable + sensation is afterwards excitable not only by a repetition of the sound, + that was then produced, but by imagination alone, as I have myself + frequently experienced; in this case the idea of biting a china cup, when + I imagine it very distinctly, or when I see another person bite a cup or + glass, excites an actual pain in the nerves of my teeth. So that this + idea and pain seem to be nothing more than the reiterated motions of + those nerves, that were formerly so disagreeably affected.</p> + + <p>Other ideas that are excited by imagination or recollection in many + instances produce similar effects on the constitution, as our perceptions + had formerly produced, and are therefore undoubtedly a repetition of the + same motions. A story which the celebrated Baron Van Swieton relates of + himself is to this purpose. He was present when the putrid carcase of a + dead dog exploded with prodigious stench; and some years afterwards, + accidentally riding along the same road, he was thrown into the same + sickness and vomiting by the idea of the stench, as he had before + experienced from the perception of it.</p> + + <p><a name="sect_III_4_4">4</a>. Where the organ of sense is totally + destroyed, the ideas which were received by that organ seem to perish + along with it, as well as the power of perception. Of this a satisfactory + instance has fallen under my observation. A gentleman about sixty years + of age had been totally deaf for near thirty years: he appeared to be a + man of good understanding, and amused himself with reading, and by + conversing either by the use of the pen, or by signs made with his + fingers, to represent letters. I observed that he had so far forgot the + pronunciation of the language, that when he attempted to speak, none of + his words had distinct articulation, though his relations could sometimes + understand his meaning. But, which is much to the point, he assured me, + that in his dreams he always imagined that people conversed with him by + signs or writing, and never that he heard any one speak to him. From + hence it appears, that with the perceptions of sounds he has also lost + the ideas of them; though the organs of speech still retain somewhat of + their usual habits of articulation.</p> + + <p>This observation may throw some light on the medical treatment of deaf + people; as it may be learnt from their dreams whether the auditory nerve + be paralytic, or their deafness be owing to some defect of the external + organ.</p> + + <p>It rarely happens that the immediate organ of vision is perfectly + destroyed. The most frequent causes of blindness are occasioned by + defects of the external organ, as in cataracts and obfuscations of the + cornea. But I have had the opportunity of conversing with two men, who + had been some years blind; one of them had a complete gutta serena, and + the other had lost the whole substance of his eyes. They both told me + that they did not remember to have ever dreamt of visible objects, since + the total loss of their sight.</p> + + <p><a name="sect_III_5">V</a>. Another method of discovering that our + ideas are animal motions of the organs of sense, is from considering the + great analogy they bear to the motions of the larger muscles of the body. + In the following articles it will appear that they are originally excited + into action by the irritation of external objects like our muscles; are + associated together like our muscular motions; act in similar time with + them; are fatigued by continued exertion like them; and that the organs + of sense are subject to inflammation, numbness, palsy, convulsion, and + the defects of old age, in the same manner as the muscular fibres.</p> + + <p><a name="sect_III_5_1">1</a>. All our perceptions or ideas of external + objects are universally allowed to have been originally excited by the + stimulus of those external objects; and it will be shewn in a succeeding + section, that it is probable that all our muscular motions, as well those + that are become voluntary as those of the heart and glandular system, + were originally in like manner excited by the stimulus of something + external to the organ of motion.</p> + + <p><a name="sect_III_5_2">2</a>. Our ideas are also associated together + after their production precisely in the same manner as our muscular + motions; which will likewise be fully explained in the succeeding + section.</p> + + <p><a name="sect_III_5_3">3</a>. The time taken up in performing an idea + is likewise much the same as that taken up in performing a muscular + motion. A musician can press the keys of an harpsichord with his fingers + in the order of a tune he has been accustomed to play, in as little time + as he can run over those 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 perception or idea of light is not changed for that + of darkness in so small a time as the twinkling of an eye; so that in + this case the muscular motion of the eye-lid is performed quicker than + the perception of light can be changed for that of darkness.—So if + a fire-stick be whirled round in the dark, a luminous circle appears to + the observer; if it be whirled somewhat slower, this circle becomes + interrupted in one part; and then the time taken up in such a revolution + of the stick is the same that the observer uses in changing his ideas: + thus the <span lang="el" title="dolikoskoton enkos" + >δολικοσκοτον + εγκος</span> of Homer, the long shadow of + the flying javelin, is elegantly designed to give us an idea of its + velocity, and not of its length.</p> + + <p><a name="sect_III_5_4">4</a>. The fatigue that follows a continued + attention of the mind to one object is relieved by changing the subject + of our thoughts; as the continued movement of one limb is relieved by + moving another in its stead. Whereas a due exercise of the faculties of + the mind strengthens and improves those faculties, whether of imagination + or recollection; as the exercise of our limbs in dancing or fencing + increases the strength and agility of the muscles thus employed.</p> + + <p><a name="sect_III_5_5">5</a>. If the muscles of any limb are inflamed, + they do not move without pain; so when the retina is inflamed, its + motions also are painful. Hence light is as intolerable in this kind of + ophthalmia, as pressure is to the finger in the paronychia. In this + disease the patients frequently dream of having their eyes painfully + dazzled; hence the idea of strong light is painful as well as the + reality. The first of these facts evinces that our perceptions are + motions of the organs of sense; and the latter, that our imaginations are + also motions of the same organs.</p> + + <p><a name="sect_III_5_6">6</a>. The organs of sense, like the moving + muscles, are liable to become benumbed, or less sensible, from + compression. Thus, if any person on a light day looks on a white wall, he + may perceive the ramifications of the optic artery, at every pulsation of + it, represented by darker branches on the white wall; which is evidently + owing to its compressing the retina during the diastole of the artery. + Savage Nosolog.</p> + + <p><a name="sect_III_5_7">7</a>. The organs of sense and the moving + muscles are alike liable to be affected with palsy, as in the gutta + serena, and in some cases of deafness; and one side of the face has + sometimes lost its power of sensation, but retained its power of motion; + other parts of the body have lost their motions but retained their + sensation, as in the common hemiplagia; and in other instances both these + powers have perished together.</p> + + <p><a name="sect_III_5_8">8</a>. In some convulsive diseases a delirium + or insanity supervenes, and the convulsions cease; and conversely the + convulsions shall supervene, and the delirium cease. Of this I have been + a witness many times in a day in the paroxysms of violent epilepsies; + which evinces that one kind of delirium is a convulsion of the organs of + sense, and that our ideas are the motions of these organs: the subsequent + cases will illustrate this observation.</p> + + <p>Miss G——, a fair young lady, with light eyes and hair, was + seized with most violent convulsions of her limbs, with outrageous + hiccough, and most vehement efforts to vomit: after near an hour was + elapsed this tragedy ceased, and a calm talkative delirium supervened for + about another hour; and these relieved each other at intervals during the + greatest part of three or four days. After having carefully considered + this disease, I thought the convulsions of her ideas less dangerous than + those of her muscles; and having in vain attempted to make any opiate + continue in her stomach, an ounce of laudanum was rubbed along the spine + of her back, and a dram of it was used as an enema; by this medicine a + kind of drunken delirium was continued many hours; and when it ceased the + convulsions did not return; and the lady continued well many years, + except some lighter relapses, which were relieved in the same manner.</p> + + <p>Miss H——, an accomplished young lady, with light eyes and + hair, was seized with convulsions of her limbs, with hiccough, and + efforts to vomit, more violent than words can express; these continued + near an hour, and were succeeded with a cataleptic spasm of one arm, with + the hand applied to her head; and after about twenty minutes these spasms + ceased, and a talkative reverie supervened for near an other hour, from + which no violence, which it was proper to use, could awaken her. These + periods of convulsions, first of the muscles, and then of the ideas, + returned twice a day for several weeks; and were at length removed by + great doses of opium, after a great variety of other medicines and + applications had been in vain experienced. This lady was subject to + frequent relapses, once or twice a year for many years, and was as + frequently relieved by the same method.</p> + + <p>Miss W——, an elegant young lady, with black eyes and hair, + had sometimes a violent pain of her side, at other times a most painful + strangury, which were every day succeeded by delirium; which gave a + temporary relief to the painful spasms. After the vain exhibition of + variety of medicines and applications by different physicians, for more + than a twelvemonth, she was directed to take some doses of opium, which + were gradually increased, by which a drunken delirium was kept up for a + day or two, and the pains prevented from returning. A flesh diet, with a + little wine or beer, instead of the low regimen she had previously used, + in a few weeks completely established her health; which, except a few + relapses, has continued for many years.</p> + + <p><a name="sect_III_5_9">9</a>. Lastly, as we advance in life all the + parts of the body become more rigid, and are rendered less susceptible of + new habits of motion, though they retain those that were before + established. This is sensibly observed by those who apply themselves late + in life to music, fencing, or any of the mechanic arts. In the same + manner many elderly people retain the ideas they had learned early in + life, but find great difficulty in acquiring new trains of memory; + insomuch that in extreme old age we frequently see a forgetfulness of the + business of yesterday, and at the same time a circumstantial remembrance + of the amusements of their youth; till at length the ideas of + recollection and activity of the body gradually cease + together,—such is the condition of humanity!—and nothing + remains but the vital motions and sensations.</p> + + <p><a name="sect_III_6">VI</a>. <a name="sect_III_6_1">1</a>. In + opposition to this doctrine of the production of our ideas, it may be + asked, if some of our ideas, like other animal motions, are voluntary, + why can we not invent new ones, that have not been received by + perception? The answer will be better understood after having perused the + succeeding section, where it will be explained, that the muscular motions + likewise are originally excited by the stimulus of bodies external to the + moving organ; and that the will has only the power of repeating the + motions thus excited.</p> + + <p><a name="sect_III_6_2">2</a>. Another objector may ask, Can the motion + of an organ of sense resemble an odour or a colour? To which I can only + answer, that it has not been demonstrated that any of our ideas resemble + the objects that excite them; it has generally been believed that they do + not; but this shall be discussed at large in Sect. <a + href="#sect_XIV">XIV</a>.</p> + + <p><a name="sect_III_6_3">3</a>. There is another objection that at first + view would seem less easy to surmount. After the amputation, of a foot or + a finger, it has frequently happened, that an injury being offered to the + stump of the amputated limb, whether from cold air, too great pressure, + or other accidents, the patient has complained, of a sensation of 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 sense? This + objection is answered, by observing that our ideas of the shape, place, + and solidity of our limbs, are acquired by our organs of touch and of + sight, which are situated in our fingers and eyes, and not by any + sensations in the limb itself.</p> + + <p>In this case the pain or sensation, which formerly has arisen in the + foot or toes, and been propagated along the nerves to the central part of + the sensorium, was at the same time accompanied with a visible idea of + the shape and place, and with a tangible idea of the solidity of the + affected limb: now when these nerves are afterwards affected by any + injury done to the remaining stump with a similar degree or kind of pain, + the ideas of the shape, place, or solidity of the lost limb, return by + association; as these ideas belong to the organs of sight and touch, on + which they were first excited.</p> + + <p><a name="sect_III_6_4">4</a>. If you wonder what organs of sense can + be excited into motion, when you call up the ideas of wisdom or + benevolence, which Mr. Locke has termed abstracted ideas; I ask you by + what organs of sense you first became acquainted with these ideas? And + the answer will be reciprocal; for it is certain that all our ideas were + originally acquired by our organs of sense; for whatever excites our + perception must be external to the organ that perceives it, and we have + no other inlets to knowledge but by our perceptions: as will be further + explained in Section <a href="#sect_XIV">XIV</a>. and <a + href="#sect_XV">XV</a>. on the Productions and Classes of Ideas.</p> + + <p><a name="sect_III_7">VII</a>. If our recollection or imagination be + not a repetition of animal movements, I ask, in my turn, What is it? You + tell me it consists of images or pictures of things. Where is this + extensive canvas hung up? or where are the numerous receptacles in which + those are deposited? or to what else in the animal system have they any + similitude?</p> + + <p>That pleasing picture of objects, represented in miniature on the + retina of the eye, seems to have given rise to this illusive oratory! It + was forgot that this representation belongs rather to the laws of light, + than to those of life; and may with equal elegance be seen in the camera + obscura as in the eye; and that the picture vanishes for ever, when the + object is withdrawn.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_IV">IV</a>.</h3> + +<p class="center" style="margin-top: 2em;">LAWS OF ANIMAL CAUSATION.</p> + + <p><a name="sect_IV_1">I</a>. The fibres, which constitute the muscles + and organs of sense, possess a power of contraction. The circumstances + attending the exertion of this power of <font + class="sc">CONTRACTION</font> constitute the laws of animal motion, as + the circumstances attending the exertion of the power of <font + class="sc">ATTRACTION</font> constitute the laws of motion of inanimate + matter.</p> + + <p><a name="sect_IV_2">II</a>. The spirit of animation is the immediate + cause of the contraction of animal fibres, it resides in the brain and + nerves, and is liable to general or partial diminution or + accumulation.</p> + + <p><a name="sect_IV_3">III</a>. The stimulus of bodies external to the + moving organ is the remote cause of the original contractions of animal + fibres.</p> + + <p><a name="sect_IV_4">IV</a>. A certain quantity of stimulus produces + irritation, which is an exertion of the spirit of animation exciting the + fibres into contraction.</p> + + <p><a name="sect_IV_5">V</a>. A certain quantity of contraction of animal + fibres, if it be perceived at all, produces pleasure; a greater or less + quantity of contraction, if it be perceived at all, produces pain; these + constitute sensation.</p> + + <p><a name="sect_IV_6">VI</a>. A certain quantity of sensation produces + desire or aversion; these constitute volition.</p> + + <p><a name="sect_IV_7">VII</a>. All animal motions which have occurred at + the same time, or in immediate succession, become so connected, that when + one of them is reproduced, the other has a tendency to accompany or + succeed it. When fibrous contractions succeed or accompany other fibrous + contractions, the connection is termed association; when fibrous + contractions succeed sensorial motions, the connexion is termed + causation; when fibrous and sensorial motions reciprocally introduce each + other, it is termed catenation of animal motions. All these connections + are said to be produced by habit, that is, by frequent repetition. These + laws of animal causation will be evinced by numerous facts, which occur + in our daily exertions; and will afterwards be employed to explain the + more recondite phænomena of the production, growth, diseases, and decay + of the animal system.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_V">V</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE FOUR FACULTIES OR MOTIONS OF THE SENSORIUM.</p> + +<blockquote class="b1"> + + <p><a href="#sect_V_1">1</a>. <i>Four sensorial powers.</i> <a + href="#sect_V_2">2</a>. <i>Irritation, sensation, volition, association + defined.</i> <a href="#sect_V_3">3</a>. <i>Sensorial motions + distinguished from fibrous motions.</i></p> + +</blockquote> + + <p><a name="sect_V_1">1</a>. The spirit of animation has four different + modes of action, or in other words the animal sensorium possesses four + different faculties, which are occasionally exerted, and cause all the + contractions of the fibrous parts of the body. These are the faculty of + causing fibrous contractions in consequence of the irritations excited by + external bodies, in consequence of the sensations of pleasure or pain, in + consequence of volition, and in consequence of the associations of + fibrous contractions with other fibrous contractions, which precede or + accompany them.</p> + + <p>These four faculties of the sensorium during their inactive state are + termed irritability, sensibility, voluntarity, and associability; in + their active state they are termed as above, irritation, sensation, + volition, association.</p> + + <p><a name="sect_V_2">2</a>. I<font class="sc">RRITATION</font> is an + exertion or change of some extreme part of the sensorium residing in the + muscles or organs of sense, in consequence of the appulses of external + bodies.</p> + + <p>S<font class="sc">ENSATION</font> is an exertion or change of the + central parts of the sensorium, or of the whole of it, <i>beginning</i> + at some of those extreme parts of it, which reside in the muscles or + organs of sense.</p> + + <p>V<font class="sc">OLITION</font> is an exertion or change of the + central parts of the sensorium, or of the whole of it, <i>terminating</i> + in some of those extreme parts of it, which reside in the muscles or + organs of sense.</p> + + <p>A<font class="sc">SSOCIATION</font> is an exertion or change of some + extreme part of the sensorium residing in the muscles or organs of sense, + in consequence of some antecedent or attendant fibrous contractions.</p> + + <p><a name="sect_V_3">3</a>. These four faculties of the animal sensorium + may at the time of their exertions be termed motions without impropriety + of language; for we cannot pass from a state of insensibility or inaction + to a state of sensibility or of exertion without some change of the + sensorium, and every change includes motion. We shall therefore sometimes + term the above described faculties <i>sensorial motions</i> to + distinguish them from <i>fibrous motions</i>; which latter expression + includes the motions of the muscles and organs of sense.</p> + + <p>The active motions of the fibres, whether those of the muscles or + organs of sense, are probably simple contractions; the fibres being again + elongated by antagonist muscles, by circulating fluids, or sometimes by + elastic ligaments, as in the necks of quadrupeds. The sensorial motions, + which constitute the sensations of pleasure or pain, and which constitute + volition, and which cause the fibrous contractions in consequence of + irritation or of association, are not here supposed to be fluctuations or + refluctuations of the spirit of animation; nor are they supposed to be + vibrations or revibrations, nor condensations or equilibrations of it; + but to be changes or motions of it peculiar to life.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_VI">VI</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE FOUR CLASSES OF FIBROUS MOTIONS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_VI_1">I</a>. <i>Origin of fibrous contractions.</i> <a + href="#sect_VI_2">II</a>. <i>Distribution of them into four classes, + irritative motions, sensitive motions, voluntary motions, and associate + motions, defined.</i></p> + +</blockquote> + + <p><a name="sect_VI_1">I</a>. All the fibrous contractions of animal + bodies originate from the sensorium, and resolve themselves into four + classes, correspondent with the four powers or motions of the sensorium + above described, and from which they have their causation.</p> + + <p><a name="sect_VI_1_1">1</a>. These fibrous contractions were + originally caused by the irritations excited by objects, which are + external to the moving organ. As the pulsations of the heart are owing to + the irritations excited by the stimulus of the blood; and the ideas of + perception are owing to the irritations excited by external bodies.</p> + + <p><a name="sect_VI_1_2">2</a>. But as painful or pleasurable sensations + frequently accompanied those irritations, by habit these fibrous + contractions became causeable by the sensations, and the irritations + ceased to be necessary to their production. As the secretion of tears in + grief is caused by the sensation of pain; and the ideas of imagination, + as in dreams or delirium, are excited by the pleasure or pain, with which + they were formerly accompanied.</p> + + <p><a name="sect_VI_1_3">3</a>. But as the efforts of the will frequently + accompanied these painful or pleasureable sensations, by habit the + fibrous contractions became causable by volition; and both the + irritations and sensations ceased to be necessary to their production. As + the deliberate locomotions of the body, and the ideas of recollection, as + when we will to repeat the alphabet backwards.</p> + + <p><a name="sect_VI_1_4">4</a>. But as many of these fibrous contractions + frequently accompanied other fibrous contractions, by habit they became + causable by their associations with them; and the irritations, + sensations, and volition, ceased to be necessary to their production. As + the actions of the muscles of the lower limbs in fencing are associated + with those of the arms; and the ideas of suggestion are associated with + other ideas, which precede or accompany them; as in repeating carelessly + the alphabet in its usual order after having began it.</p> + + <p><a name="sect_VI_2">II</a>. We shall give the following names to these + four classes of fibrous motions, and subjoin their definitions.</p> + + <p><a name="sect_VI_2_1">1</a>. Irritative motions. That exertion or + change of the sensorium, which is caused by the appulses of external + bodies, either simply subsides, or is succeeded by sensation, or it + produces fibrous motions; it is termed irritation, and irritative motions + are those contractions of the muscular fibres, or of the organs of sense, + that are immediately consequent to this exertion or change of the + sensorium.</p> + + <p><a name="sect_VI_2_2">2</a>. Sensitive motions. That exertion or + change of the sensorium, which constitutes pleasure or pain, either + simply subsides, or is succeeded by volition, or it produces fibrous + motions; it is termed sensation, and the sensitive motions are those + contractions of the muscular fibres, or of the organs of sense, that are + immediately consequent to this exertion or change of the sensorium.</p> + + <p><a name="sect_VI_2_3">3</a>. Voluntary motions. That exertion or + change of the sensorium, which constitutes desire or aversion, either + simply subsides, or is succeeded by fibrous motions; it is then termed + volition, and voluntary motions are those contractions of the muscular + fibres, or of the organs of sense, that are immediately consequent to + this exertion or change of the sensorium.</p> + + <p><a name="sect_VI_2_4">4</a>. Associate motions. That exertion or + change of the sensorium, which accompanies fibrous motions, either simply + subsides, or is succeeded by sensation or volition, or it produces other + fibrous motions; it is then termed association, and the associate motions + are those contractions of the muscular fibres, or of the organs of sense, + that are immediately consequent to this exertion or change of the + sensorium.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_VII">VII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF IRRITATIVE MOTIONS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_VII_1">I</a>. <a href="#sect_VII_1_1">1</a>. <i>Some + muscular motions are excited by perpetual irritations.</i> <a + href="#sect_VII_1_2">2</a>. <i>Others more frequently by sensations.</i> + <a href="#sect_VII_1_3">3</a>. <i>Others by volition. Case of involuntary + stretchings in paralytic limbs.</i> <a href="#sect_VII_1_4">4</a>. + <i>Some sensual motions are excited by perpetual irritations.</i> <a + href="#sect_VII_1_5">5</a>. <i>Others more frequently by sensation or + volition.</i></p> + + <p><a href="#sect_VII_2">II</a>. <a href="#sect_VII_2_1">1</a>. + <i>Muscular motions excited by perpetual irritations occasionally become + obedient sensation and to volition.</i> <a href="#sect_VII_2_2">2</a>. + <i>And the sensual motions.</i></p> + + <p><a href="#sect_VII_3">III</a>. <a href="#sect_VII_3_1">1</a>. <i>Other + muscular motions are associated with the irritative ones.</i> <a + href="#sect_VII_3_2">2</a>. <i>And other ideas with irritative ones. Of + letters, language, hieroglyphics. Irritative ideas exist without our + attention to them.</i></p> + +</blockquote> + + <p><a name="sect_VII_1">I</a>. <a name="sect_VII_1_1">1</a>. Many of our + muscular motions are excited by perpetual irritations, as those of the + heart and arterial system by the circumfluent blood. Many other of them + are excited by intermitted irritations, as those of the stomach and + bowels by the aliment we swallow; of the bile-ducts by the bile; of the + kidneys, pancreas, and many other glands, by the peculiar fluids they + separate from the blood; and those of the lacteal and other absorbent + vessels by the chyle, lymph, and moisture of the atmosphere. These + motions are accelerated or retarded, as their correspondent irritations + are increased or diminished, without our attention or consciousness, in + the same manner as the various secretions of fruit, gum, resin, wax, and, + honey, are produced in the vegetable world, and as the juices of the + earth and the moisture of the atmosphere are absorbed by their roots and + foliage.</p> + + <p><a name="sect_VII_1_2">2</a>. Other muscular motions, that are most + frequently connected with our sensations, as those of the sphincters of + the bladder and anus, and the musculi erectores penis, were originally + excited into motion by irritation, for young children make water, and + have other evacuations without attention to these circumstances; "et + primis etiam ab incunabulis tenduntur sæpius puerorum penes, amore nondum + expergefacto." So the nipples of young women are liable to become turgid + by irritation, long before they are in a situation to be excited by the + pleasure of giving milk to the lips of a child.</p> + + <p><a name="sect_VII_1_3">3</a>. The contractions of the larger muscles + of our bodies, that are most frequently connected with volition, were + originally excited into action by internal irritations: as appears from + the stretching or yawning of all animals after long sleep. In the + beginning of some fevers this irritation of the muscles produces + perpetual stretching and yawning; in other periods of fever an universal + restlessness arises from the same cause, the patient changing the + attitude of his body every minute. The repeated struggles of the + fœtus in the uterus must be owing to this internal irritation: for + the fœtus can have no other inducement to move its limbs but the + tædium or irksomeness of a continued posture.</p> + + <p>The following case evinces, that the motions of stretching the limbs + after a continued attitude are not always owing to the power of the will. + Mr. Dean, a mason, of Austry in Leicestershire, had the spine of the + third vertebra of the back enlarged; in some weeks his lower extremities + became feeble, and at length quite paralytic: neither the pain of + blisters, the heat of fomentations, nor the utmost efforts of the will + could produce the least motion in these limbs; yet twice or thrice a day + for many months his feet, legs, and thighs, were affected for many + minutes with forceable stretchings, attended with the sensation of + fatigue; and he at length recovered the use of his limbs, though the + spine continued protuberant. The same circumstance is frequently seen in + a less degree in the common hemiplagia; and when this happens, I have + believed repeated and strong shocks of electricity to have been of great + advantage.</p> + + <p><a name="sect_VII_1_4">4</a>. In like manner the various organs of + sense are originally excited into motion by various external stimuli + adapted to this purpose, which motions are termed perceptions or ideas; + and many of these motions during our waking hours are excited by + perpetual irritation, as those of the organs of hearing and of touch. The + former by the constant low indistinct noises that murmur around us, and + the latter by the weight of our bodies on the parts which support them; + and by the unceasing variations of the heat, moisture, and pressure of + the atmosphere; and these sensual motions, precisely as the muscular ones + above mentioned, obey their correspondent irritations without our + attention or consciousness.</p> + + <p><a name="sect_VII_1_5">5</a>. Other classes of our ideas are more + frequently excited by our sensations of pleasure or pain, and others by + volition: but that these have all been originally excited by stimuli from + external objects, and only vary in their combinations or reparations, has + been fully evinced by Mr. Locke: and are by him termed the ideas of + perception in contradistinction to those, which he calls the ideas of + reflection.</p> + + <p><a name="sect_VII_2">II</a>. <a name="sect_VII_2_1">1</a>. These + muscular motions, that are excited by perpetual irritation, are + nevertheless occasionally excitable by the sensations of pleasure or + pain, or by volition; as appears by the palpitation of the heart from + fear, the increased secretion of saliva at the sight of agreeable food, + and the glow on the skin of those who are ashamed. There is an instance + told in the Philosophical Transactions of a man, who could for a time + stop the motion of his heart when he pleased; and Mr. D. has often told + me, be could so far increase the peristaltic motion of his bowels by + voluntary efforts, as to produce an evacuation by stool at any time in + half an hour.</p> + + <p><a name="sect_VII_2_2">2</a>. In like manner the sensual motions, or + ideas, that are excited by perpetual irritation, are nevertheless + occasionally excited by sensation or volition; as in the night, when we + listen under the influence of fear, or from voluntary attention, the + motions excited in the organ of hearing by the whispering of the air in + our room, the pulsation of our own arteries, or the faint beating of a + distant watch, become objects of perception.</p> + + <p><a name="sect_VII_3">III</a>. <a name="sect_VII_3_1">1</a>. + Innumerable trains or tribes of other motions are associated with these + muscular motions which are excited by irritation; as by the stimulus of + the blood in the right chamber of the heart, the lungs are induced to + expand themselves; and the pectoral and intercostal muscles, and the + diaphragm, act at the same time by their associations with them. And when + the pharinx is irritated by agreeable food, the muscles of deglutition + are brought into action by association. Thus when a greater light falls + on the eye, the iris is brought into action without our attention; and + the ciliary process, when the focus is formed before or behind the + retina, by their associations with the increased irritative motions of + the organ of vision. Many common actions of life are produced in a + similar manner. If a fly settle on my forehead, whilst I am intent on my + present occupation, I dislodge it with my finger, without exciting my + attention or breaking the train of my ideas.</p> + + <p><a name="sect_VII_3_2">2</a>. In like manner the irritative ideas + suggest to us many other trains or tribes of ideas that are associated + with them. On this kind of connection, language, letters, hieroglyphics, + and every kind of symbol, depend. The symbols themselves produce + irritative ideas, or sensual motions, which we do not attend to; and + other ideas, that are succeeded by sensation, are excited by their + association with them. And as these irritative ideas make up a part of + the chain of our waking thoughts, introducing other ideas that engage our + attention, though themselves are unattended to, we find it very difficult + to investigate by what steps many of our hourly trains of ideas gain + their admittance.</p> + + <p>It may appear paradoxical, that ideas can exist, and not be attended + to; but all our perceptions are ideas excited by irritation, and + succeeded by sensation. Now when these ideas excited by irritation give + us neither pleasure nor pain, we cease to attend to them. Thus whilst I + am walking through that grove before my window, I do not run against the + trees or the benches, though my thoughts are strenuously exerted on some + other object. This leads us to a distinct knowledge of irritative ideas, + for the idea of the tree or bench, which I avoid, exists on my retina, + and induces by association the action of certain locomotive muscles; + though neither itself nor the actions of those muscles engage my + attention.</p> + + <p>Thus whilst we are conversing on this subject, the tone, note, and + articulation of every individual word forms its correspondent irritative + idea on the organ of hearing; but we only attend to the associated ideas, + that are attached by habit to these irritative ones, and are succeeded by + sensation; thus when we read the words "<font + class="sc">PRINTING-PRESS</font>" we do not attend to the shape, size, or + existence of the letters which compose these words, though each of them + excites a correspondent irritative motion of our organ of vision, but + they introduce by association our idea of the most useful of modern + inventions; the capacious reservoir of human knowledge, whose branching + streams diffuse sciences, arts, and morality, through all nations and all + ages.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_VIII">VIII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF SENSITIVE MOTIONS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_VIII_1">I</a>. <a href="#sect_VIII_1_1">1</a>. + <i>Sensitive muscular motions were originally excited into action by + irritation.</i> <a href="#sect_VIII_1_2">2</a>. <i>And sensitive sensual + motions, ideas of imagination, dreams.</i> <a href="#sect_VIII_2">II</a>. + <a href="#sect_VIII_2_1">1</a>. <i>Sensitive muscular motions are + occasionally obedient to volition.</i> <a href="#sect_VIII_2_2">2</a>. + <i>And sensitive sensual motions.</i> <a href="#sect_VIII_3">III</a>. <a + href="#sect_VIII_3_1">1</a>. <i>Other muscular motions are associated + with the sensitive ones.</i> <a href="#sect_VIII_3_2">2</a>. <i>And other + sensual motions.</i></p> + +</blockquote> + + <p><a name="sect_VIII_1">I</a>. <a name="sect_VIII_1_1">1</a>. Many of + the motions of our muscles, that are excited into action by irritation, + are at the same time accompanied with painful or pleasurable sensations; + and at length become by habit causable by the sensations. Thus the + motions of the sphincters of the bladder and anus were originally excited + into action by irritation; for young children give no attention to these + evacuations; but as soon as they become sensible of the inconvenience of + obeying these irritations, they suffer the water or excrement to + accumulate, till it disagreeably affects them; and the action of those + sphincters is then in consequence of this disagreeable sensation. So the + secretion of saliva, which in young children is copiously produced by + irritation, and drops from their mouths, is frequently attended with the + agreeable sensation produced by the mastication of tasteful food;, till + at length the sight of such food to a hungry person excites into action + these salival glands; as is seen in the slavering of hungry dogs.</p> + + <p>The motions of those muscles, which are affected by lascivious ideas, + and those which are exerted in smiling, weeping, starting from fear, and + winking at the approach of danger to the eye, and at times the actions of + every large muscle of the body become causable by our sensations. And all + these motions are performed with strength and velocity in proportion to + the energy of the sensation that excites them, and the quantity of + sensorial power.</p> + + <p><a name="sect_VIII_1_2">2</a>. Many of the motions of our organs of + sense, or ideas, that were originally excited into action by irritation, + become in like manner more frequently causable by our sensations of + pleasure or pain. These motions are then termed the ideas of imagination, + and make up all the scenery and transactions of our dreams. Thus when any + painful or pleasurable sensations possess us, as of love, anger, fear; + whether in our sleep or waking hours, the ideas, that have been formerly + excited by the objects of these sensations, now vividly recur before us + by their connection with these sensations themselves. So the fair smiling + virgin, that excited your love by her presence, whenever that sensation + recurs, rises before you in imagination; and that with all the pleasing + circumstances, that had before engaged your attention. And in sleep, when + you dream under the influence of fear, all the robbers, fires, and + precipices, that you formerly have seen or heard of, arise before you + with terrible vivacity. All these sensual motions, like the muscular ones + above mentioned, are performed with strength and velocity in proportion + to the energy of the sensation of pleasure or pain, which excites them, + and the quantity of sensorial power.</p> + + <p><a name="sect_VIII_2">II</a>. <a name="sect_VIII_2_1">1</a>. Many of + these muscular motions above described, that are most frequently excited + by our sensations, are nevertheless occasionally causable by volition; + for we can smile or frown spontaneously, can make water before the + quantity or acrimony of the urine produces a disagreeable sensation, and + can voluntarily masticate a nauseous drug, or swallow a bitter draught, + though our sensation would strongly dissuade us.</p> + + <p><a name="sect_VIII_2_2">2</a>. In like manner the sensual motions, or + ideas, that are most frequently excited by our sensations, are + nevertheless occasionally causeable by volition, as we can spontaneously + call up our last night's dream before us, tracing it industriously step + by step through all its variety of scenery and transaction; or can + voluntarily examine or repeat the ideas, that have been excited by out + disgust or admiration.</p> + + <p><a name="sect_VIII_3">III</a>. <a name="sect_VIII_3_1">1</a>. + Innumerable trains or tribes of motions are associated with these + sensitive muscular motions above mentioned; as when a drop of water + falling into the wind-pipe disagreeably affects the air-vessels of the + lungs, they are excited into violent action; and with these sensitive + motions are associated the actions of the pectoral and intercostal + muscles, and the diaphragm; till by their united and repeated succussions + the drop is returned through the larinx. The same occurs when any thing + disagreeably affects the nostrils, or the stomach, or the uterus; variety + of muscles are excited by association into forcible action, not to be + suppressed by the utmost efforts of the will; as in sneezing, vomiting, + and parturition.</p> + + <p><a name="sect_VIII_3_2">2</a>. In like manner with these sensitive + sensual motions, or ideas of imagination, are associated many other + trains or tribes of ideas, which by some writers of metaphysics have been + classed under the terms of resemblance, causation, and contiguity; and + will be more fully treated of hereafter.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_IX">IX</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF VOLUNTARY MOTIONS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_IX_1">I</a>. <a href="#sect_IX_1_1">1</a>. <i>Voluntary + muscular motions are originally excited by irritations.</i> <a + href="#sect_IX_1_2">2</a>. <i>And voluntary ideas. Of reason.</i> <a + href="#sect_IX_2">II</a>. <a href="#sect_IX_2_1">1</a>. <i>Voluntary + muscular motions are occasionally causable by sensations.</i> <a + href="#sect_IX_2_2">2</a>. <i>And voluntary ideas.</i> <a + href="#sect_IX_3">III</a>. <a href="#sect_IX_3_1">1</a>. <i>Voluntary + muscular motions are occasionally obedient to irritations.</i> <a + href="#sect_IX_3_2">2</a>. <i>And voluntary ideas.</i> <a + href="#sect_IX_4">IV</a>. <a href="#sect_IX_4_1">1</a>. <i>Voluntary + muscular motions are associated with other muscular motions.</i> <a + href="#sect_IX_4_2">2</a>. <i>And voluntary ideas.</i></p> + +</blockquote> + + <p>When pleasure or pain affect the animal system, many of its motions + both muscular and sensual are brought into action; as was shewn in the + preceding section, and were called sensitive motions. The general + tendency of these motions is to arrest and to possess the pleasure, or to + dislodge or avoid the pain: but if this cannot immediately be + accomplished, desire or aversion are produced, and the motions in + consequence of this new faculty of the sensorium are called + voluntary.</p> + + <p><a name="sect_IX_1">I</a>. <a name="sect_IX_1_1">1</a>. Those muscles + of the body that are attached to bones, have in general their principal + connections with volition, as I move my pen or raise my body. These + motions were originally excited by irritation, as was explained in the + section on that subject, afterwards the sensations of pleasure or pain, + that accompanied the motions thus excited, induced a repetition of them; + and at length many of them were voluntarily practised in succession or in + combination for the common purposes of life, as in learning to walk, or + to speak; and are performed with strength and velocity in proportion to + the energy of the volition, that excites them, and the quantity of + sensorial power.</p> + + <p><a name="sect_IX_1_2">2</a>. Another great class of voluntary motions + consists 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 + belong to this intended train, intrude themselves by other connections, + we will to reject them, and voluntarily persist in the determined train. + So at my approach to a house which I have but once visited, and that at + the distance of many months, I will to recollect the names of the + numerous family I expect to see there, and I do recollect them.</p> + + <p>On this voluntary recollection of ideas our faculty of reason depends, + as it enables us to acquire an idea of the dissimilitude of any two + ideas. Thus if you voluntarily produce the idea of a right-angled + triangle, and then of a square; and after having excited these ideas + repeatedly, you excite the idea of their difference, which is that of + another right-angled triangle inverted over the former; you are said to + reason upon this subject, or to compare your ideas.</p> + + <p>These ideas of recollection, like the muscular motions above + mentioned, were originally excited by the irritation of external bodies, + and were termed ideas of perception: afterwards the pleasure or pain, + that accompanied these motions, induced a repetition of them in the + absence of the external body, by which they were first excited; and then + they were termed ideas of imagination. At length they become voluntarily + practised in succession or in combination for the common purposes of + life; as when we make ourselves masters of the history of mankind, or of + the sciences they have investigated; 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 + sensorial power.</p> + + <p><a name="sect_IX_2">II</a>. <a name="sect_IX_2_1">1</a>. The muscular + motions above described, that are most frequently obedient to the will + are nevertheless occasionally causable by painful or pleasurable + sensation, as in the starting from fear, and the contraction of the calf + of the leg in the cramp.</p> + + <p><a name="sect_IX_2_2">2</a>. In like manner the sensual motions, or + ideas, that are most frequently connected with volition, are nevertheless + occasionally causable by painful or pleasurable sensation. As the + histories of men, or the description of places, which we have voluntarily + taken pains to remember, sometimes occur to us in our dreams.</p> + + <p><a name="sect_IX_3">III</a>. <a name="sect_IX_3_1">1</a>. The muscular + motions that are generally subservient to volition, are also occasionally + causable by irritation, as in stretching the limbs after sleep, and + yawning. In this manner a contraction of the arm is produced by passing + the electric fluid from the Leyden phial along its muscles; and that even + though the limb is paralytic. The sudden motion of the arm produces a + disagreeable sensation in the joint, but the muscles seem to be brought + into action simply by irritation.</p> + + <p><a name="sect_IX_3_2">2</a>. The ideas, that are generally subservient + to the will, are in like manner occasionally excited by irritation; as + when we view again an object, we have before well studied, and often + recollected.</p> + + <p><a name="sect_IX_4">IV</a>. <a name="sect_IX_4_1">1</a>. Innumerable + trains or tribes of motions are associated with these voluntary muscular + motions above mentioned; as when I will to extend my arm to a distant + object, some other muscles are brought into action, and preserve the + balance of my body. And when I wish to perform any steady exertion, as in + threading a needle, or chopping with an ax, the pectoral muscles are at + the same time brought into action to preserve the trunk of the body + motionless, and we cease to respire for a time.</p> + + <p><a name="sect_IX_4_2">2</a>. In like manner the voluntary sensual + motions, or ideas of recollection, are associated with many other trains + or tribes of ideas. As when I voluntarily recollect a gothic window, that + I saw some time ago, the whole front of the cathedral occurs to me at the + same time.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_X">X</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF ASSOCIATE MOTIONS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_X_1">I</a>. <a href="#sect_X_1_1">1</a>. <i>Many + muscular motions excited by irritations in trains or tribes become + associated.</i> <a href="#sect_X_1_2">2</a>. <i>And many ideas.</i> <a + href="#sect_X_2">II</a>. <a href="#sect_X_2_1">1</a>. <i>Many sensitive + muscular motions become associated.</i> <a href="#sect_X_2_2">2</a>. + <i>And many sensitive ideas.</i> <a href="#sect_X_3">III</a>. <a + href="#sect_X_3_1">1</a>. <i>Many voluntary muscular motions become + associated.</i> <a href="#sect_X_3_2">2</a>. <i>And then become obedient + to sensation or irritation.</i> <a href="#sect_X_3_3">3</a>. <i>And many + voluntary ideas become associated.</i></p> + +</blockquote> + + <p>All the fibrous motions, whether muscular or sensual, which are + frequently brought into action together, either in combined tribes, or in + successive trains, become so connected by habit, that when one of them is + reproduced the others have a tendency to succeed or accompany it.</p> + + <p><a name="sect_X_1">I</a>. <a name="sect_X_1_1">1</a>. Many of our + muscular motions were originally excited in successive trains, as the + contractions of the auricles and of the ventricles of the heart; and + others in combined tribes, as the various divisions of the muscles which + compose the calf of the leg, which were originally irritated into + synchronous action by the tædium or irksomeness of a continued posture. + By frequent repetitions these motions acquire associations, which + continue during our lives, and even after the destruction of the greatest + part of the sensorium; for the heart of a viper or frog will continue to + pulsate long after it is taken from the body; and when it has entirely + ceased to move, if any part of it is goaded with a pin, the whole heart + will again renew its pulsations. This kind of connection we shall term + irritative association, to distinguish it from sensitive and voluntary + associations.</p> + + <p><a name="sect_X_1_2">2</a>. In like manner many of our ideas are + originally excited in tribes; as all the objects of sight, after we + become so well acquainted with the laws of vision, as to distinguish + figure and distance as well as colour; or in trains, as while we pass + along the objects that surround us. The tribes thus received by + irritation become associated by habit, and have been termed complex ideas + by the writers of metaphysics, as this book, or that orange. The trains + have received no particular name, but these are alike associations of + ideas, and frequently continue during our lives. So the taste of a + pine-apple, though we eat it blindfold, recalls the colour and shape of + it; and we can scarcely think on solidity without figure.</p> + + <p><a name="sect_X_2">II</a>. <a name="sect_X_2_1">1</a>. By the various + efforts of our sensations to acquire or avoid their objects, many muscles + are daily brought into successive or synchronous actions; these become + associated by habit, and are then excited together with great facility, + and in many instances gain indissoluble connections. So the play of + puppies and kittens is a representation of their mode of fighting or of + taking their prey; and the motions of the muscles necessary for those + purposes become associated by habit, and gain a great adroitness of + action by these early repetitions: so the motions of the abdominal + muscles, which were originally brought into concurrent action, with the + protrusive motion of the rectum or bladder by sensation, become so + conjoined with them by habit, that they not only easily obey these + sensations occasioned by the stimulus of the excrement and urine, but are + brought into violent and unrestrainable action in the strangury and + tenesmus. This kind of connection we shall term sensitive + association.</p> + + <p><a name="sect_X_2_2">2</a>. So many of our ideas, that have been + excited together or in succession by our sensations, gain synchronous or + successive associations, that are sometimes indissoluble but with life. + Hence the idea of an inhuman or dishonourable action perpetually calls up + before us the idea of the wretch that was guilty of it. And hence those + unconquerable antipathies are formed, which some people have to the sight + of peculiar kinds of food, of which in their infancy they have eaten to + excess or by constraint.</p> + + <p><a name="sect_X_3">III</a>. <a name="sect_X_3_1">1</a>. In learning + any mechanic art, as music, dancing, or the use of the sword, we teach + many of our muscles to act together or in succession by repeated + voluntary efforts; which by habit become formed into tribes or trains of + association, and serve all our purposes with great facility, and in some + instances acquire an indissoluble union. These motions are gradually + formed into a habit of acting together by a multitude of repetitions, + whilst they are yet separately causable by the will, as is evident from + the long time that is taken up by children in learning to walk and to + speak; and is experienced by every one, when he first attempts to skate + upon the ice or to swim: these we shall term voluntary associations.</p> + + <p><a name="sect_X_3_2">2</a>. All these muscular movements, when they + are thus associated into tribes or trains, become afterwards not only + obedient to volition, but to the sensations and irritations; and the same + movement composes a part of many different tribes or trains of motion. + Thus a single muscle, when it acts in consort with its neighbours on one + side, assists to move the limb in one direction; and in another, when, it + acts with those in its neighbourhood on the other side; and in other + directions, when it acts separately or jointly with those that lie + immediately under or above it; and all these with equal facility after + their associations have been well established.</p> + + <p>The facility, with which each muscle changes from one associated tribe + to another, and that either backwards or forwards, is well observable in + the muscles of the arm in moving the windlass of an air-pump; and the + slowness of those muscular movements, that have not been associated by + habit, may be experienced by any one, who shall attempt to saw the air + quick perpendicularly with one hand, and horizontally with the other at + the same time.</p> + + <p><a name="sect_X_3_3">3</a>. In learning every kind of science we + voluntarily associate many tribes and trains of ideas, which afterwards + are ready for all the purposes either of volition, sensation, or + irritation; and in some instances acquire indissoluble habits of acting + together, so as to affect our reasoning, and influence our actions. Hence + the necessity of a good education.</p> + + <p>These associate ideas are gradually formed into habits of acting + together by frequent repetition, while they are yet separately obedient + to the will; as is evident from the difficulty we experience in gaining + so 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.</p> + + <p>And these ideas, thus associated into tribes, not only make up the + parts of the trains of volition, sensation, and irritation; but the same + idea composes a part of many different tribes and trains of ideas. So the + simple idea of whiteness composes a part of the complex idea of snow, + milk, ivory; and the complex idea of the letter A composes a part of the + several associated trains of ideas that make up the variety of words, in + which this letter enters.</p> + + <p>The numerous trains of these associated ideas are divided by Mr. Hume + into three classes, which he has termed contiguity, causation, and + resemblance. Nor should we wonder to find them thus connected together, + since it is the business of our lives to dispose them into those three + classes; and we become valuable to ourselves and our friends, as we + succeed in it. Those who have combined an extensive class of ideas by the + contiguity of time or place, are men learned in the history of mankind, + and of the sciences they have cultivated. Those who have connected a + great class of ideas of resemblances, possess the source of the ornaments + of poetry and oratory, and of all rational analogy. While those who have + connected great classes of ideas of causation, are furnished with the + powers of producing effects. These are the men of active wisdom, who lead + armies to victory, and kingdoms to prosperity; or discover and improve + the sciences, which meliorate and adorn the condition of humanity.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XI">XI</a>.</h3> + +<p class="center" style="margin-top: 2em;">ADDITIONAL OBSERVATIONS ON THE SENSORIAL POWERS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XI_1">I</a>. <i>Stimulation is of various kinds adapted + to the organs of sense, to the muscles, to hollow membranes, and glands. + Some objects irritate our senses by repeated impulses.</i> <a + href="#sect_XI_2">II</a>. <a href="#sect_XI_2_1">1</a>. <i>Sensation and + volition frequently affect the whole sensorium.</i> <a + href="#sect_XI_2_2">2</a>. <i>Emotions, passions, appetites.</i> <a + href="#sect_XI_2_3">3</a>. <i>Origin of desire and aversion. Criterion of + voluntary actions, difference of brutes and men.</i> <a + href="#sect_XI_2_4">4</a>. <i>Sensibility and voluntarity.</i> <a + href="#sect_XI_3">III</a>. <i>Associations formed before nativity, + irritative motions mistaken for officiated ones.</i></p> + +</blockquote> + +<p class="center" style="margin-top: 2em;"><i>Irritation.</i></p> + + <p><a name="sect_XI_1">I</a>. The various organs of sense require various + kinds of stimulation to excite them into action; the particles of light + penetrate the cornea and humours of the eye, and then irritate the naked + retina; rapid particles, dissolved or diffused in water or saliva, and + odorous ones, mixed or combined with the air, irritate the extremities of + the nerves of taste and smell; which either penetrate, or are expanded on + the membranes of the tongue and nostrils; the auditory nerves are + stimulated by the vibrations of the atmosphere communicated by means of + the tympanum and of the fluid, whether of air or of water, behind it; and + the nerves of touch by the hardness of surrounding bodies, though the + cuticle is interposed between these bodies and the medulla of the + nerve.</p> + + <p>As the nerves of the senses have each their appropriated objects, + which stimulate them into activity; so the muscular fibres, which are the + terminations of other sets of nerves, have their peculiar objects, which + excite them into action; the longitudinal muscles are stimulated into + contraction by extension, whence the stretching or pandiculation after a + long continued posture, during which they have been kept in a state of + extension; and the hollow muscles are excited into action by distention, + as those of the rectum and bladder are induced to protrude their contents + from their sense of the distention rather than of the acrimony of those + contents.</p> + + <p>There are other objects adapted to stimulate the nerves, which + terminate in variety of membranes, and those especially which form the + terminations of canals; thus the preparations of mercury particularly + affect the salivary glands, ipecacuanha the stomach, aloe the sphincter + of the anus, cantharides that of the bladder, and lastly every gland of + the body appears to be indued with a kind of taste, by which it selects + or forms each its peculiar fluid from the blood; and by which it is + irritated into activity.</p> + + <p>Many of these external properties of bodies, which stimulate our + organs of sense, do not seem to effect this by a single impulse, but by + repeated impulses; as the nerve of the ear is probably not excitable by a + single vibration of air, nor the optic nerve by a single particle of + light; which circumstance produces some analogy between those two senses, + at the same time the solidity of bodies is perceived by a single + application of a solid body to the nerves of touch, and that even through + the cuticle; and we are probably possessed of a peculiar sense to + distinguish the nice degrees of heat and cold.</p> + + <p>The senses of touch and of hearing acquaint us with the mechanical + impact and vibration of bodies, those of smell and taste seem to acquaint + us with some of their chemical properties, while the sense of vision and + of heat acquaint us with the existence of their peculiar fluids.</p> + +<p class="center" style="margin-top: 2em;"><i>Sensation and Volition.</i></p> + + <p><a name="sect_XI_2">II</a>. Many motions are produced by pleasure or + pain, and that even in contradiction to the power of volition, as in + laughing, or in the strangury; but as no name has been given to pleasure + or pain, at the time it is exerted so as to cause fibrous motions, we + have used the term sensation for this purpose; and mean it to bear the + same analogy to pleasure and pain, that the word volition does to desire + and aversion.</p> + + <p><a name="sect_XI_2_1">1</a>. It was mentioned in the fifth Section, + that, what we have termed sensation is a motion of the central parts, or + of the whole sensorium, <i>beginning</i> at some of the extremities of + it. This appears first, because our pains and pleasures are always caused + by our ideas or muscular motions, which are the motions of the + extremities of the sensorium. And, secondly, because the sensation of + pleasure or pain frequently continues some time after the ideas or + muscular motions which excited it have ceased: for we often feel a glow + of pleasure from an agreeable reverie, for many minutes after the ideas, + that were the subject of it, have escaped our memory; and frequently + experience a dejection of spirits without being able to assign the cause + of it but by much recollection.</p> + + <p>When the sensorial faculty of desire or aversion is exerted so as to + cause fibrous motions, it is termed volition; which is said in Sect. <a + href="#sect_V">V</a>. to be a motion of the central parts, or of the + whole sensorium, <i>terminating</i> in some of the extremities of it. + This appears, first, because our desires and aversions always terminate + in recollecting and comparing our ideas, or in exerting our muscles; + which are the motions of the extremities of the sensorium. And, secondly, + because desire or aversion begins, and frequently continues for a time in + the central parts of the sensorium, before it is peculiarly exerted at + the extremities of it; for we sometimes feel desire or aversion without + immediately knowing their objects, and in consequence without immediately + exerting any of our muscular or sensual motions to attain them: as in the + beginning of the passion of love, and perhaps of hunger, or in the ennui + of indolent people.</p> + + <p>Though sensation and volition begin or terminate at the extremities or + central parts of the sensorium, yet the whole of it is frequently + influenced by the exertion of these faculties, as appears from their + effects on the external habit: for the whole skin is reddened by shame, + and an universal trembling is produced by fear: and every muscle of the + body is agitated in angry people by the desire of revenge.</p> + + <p>There is another very curious circumstance, which shews that sensation + and volition are movements of the sensorium in contrary directions; that + is, that volition begins at the central parts of it, and proceeds to the + extremities; and that sensation begins at the extremities, and proceeds + to the central parts: I mean that these two sensorial faculties cannot be + strongly exerted at the same time; for when we exert our volition + strongly, we do not attend to pleasure or pain; and conversely, when we + are strongly affected with the sensation of pleasure or pain, we use no + volition. As will be further explained in Section <a + href="#sect_XVIII">XVIII</a>. on sleep, and Section <a + href="#sect_XXXIV">XXXIV</a>. on volition.</p> + + <p><a name="sect_XI_2_2">2</a>. All our emotions and passions seem to + arise out of the exertions of these two faculties of the animal + sensorium. Pride, hope, joy, are the names of particular pleasures: + shame, despair, sorrow, are the names of peculiar pains: and love, + ambition, avarice, of particular desires: hatred, disgust, fear, anxiety, + of particular aversions. Whilst the passion of anger includes the pain + from a recent injury, and the aversion to the adversary that occasioned + it. And compassion is the pain we experience at the sight of misery, and + the desire of relieving it.</p> + + <p>There is another tribe of desires, which are commonly termed + appetites, and are the immediate consequences of the absence of some + irritative motions. Those, which arise from defect of internal + irritations, have proper names conferred upon them, as hunger, thirst, + lust, and the desire of air, when our respiration is impaired by noxious + vapours; and of warmth, when we are exposed to too great a degree of + cold. But those, whose stimuli are external to the body, are named from + the objects, which are by nature constituted to excite them; these + desires originate from our past experience of the pleasurable sensations + they occasion, as the smell of an hyacinth, or the taste of a + pine-apple.</p> + + <p>Whence it appears, that our pleasures and pains are at least as + various and as numerous as our irritations; and that our desires and + aversions must be as numerous as our pleasures and pains. And that as + sensation is here used as a general term for our numerous pleasures and + pains, when they produce the contractions of our fibres; so volition is + the general name for our desires and aversions, when they produce fibrous + contractions. Thus when a motion of the central parts, or of the whole + sensorium, terminates in the exertion of our muscles, it is generally + called voluntary action; when it terminates in the exertion of our ideas, + it is termed recollection, reasoning, determining.</p> + + <p><a name="sect_XI_2_3">3</a>. As the sensations of pleasure and pain + are originally introduced by the irritations of external objects: so our + desires and aversions are originally introduced by those sensations; for + when the objects of our pleasures or pains are at a distance, and we + cannot instantaneously possess the one, or avoid the other, then desire + or aversion is produced, and a voluntary exertion of our ideas or muscles + succeeds.</p> + + <p>The pain of hunger excites you to look out for food, the tree, that + shades you, presents its odoriferous fruit before your eyes, you + approach, pluck, and eat.</p> + + <p>The various movements of walking to the tree, gathering the fruit, and + masticating it, are associated motions introduced by their connection + with sensation; but if from the uncommon height of the tree, the fruit be + inaccessible, and you are prevented from quickly possessing the intended + pleasure, desire is produced. The consequence of this desire is, first, a + deliberation about the means to gain the object of pleasure in process of + time, as it cannot be procured immediately; and, secondly, the muscular + action necessary for this purpose.</p> + + <p>You voluntarily call up all your ideas of causation, that are related + to the effect you desire, and voluntarily examine and compare them, and + at length determine whether to ascend the tree, or to gather stones from + the neighbouring brook, is easier to practise, or more promising of + success; and, finally, you gather the stones, and repeatedly fling them + to dislodge the fruit.</p> + + <p>Hence then we gain a criterion to distinguish voluntary acts or + thoughts from those caused by sensation. As the former are always + employed about the <i>means</i> to acquire pleasurable objects, or the + <i>means</i> to avoid painful ones; while the latter are employed in the + possession of those, which are already in our power.</p> + + <p>Hence the activity of this power of volition produces the great + difference between the human and the brute creation. The ideas and the + actions of brutes are almost perpetually employed about their present + pleasures, or their present pains; and, except in the few instances which + are mentioned in Section <a href="#sect_XVI">XVI</a>, on instinct, they + seldom busy themselves about the means of procuring future bliss, or of + avoiding future misery; so that the acquiring of languages, the making of + tools, and labouring for money, which are all only the means to procure + pleasures; and the praying to the Deity, as another means to procure + happiness, are characteristic of human nature.</p> + + <p><a name="sect_XI_2_4">4</a>. As there are many diseases produced by + the quantity of the sensation of pain or pleasure being too great or too + little; so are there diseases produced by the susceptibility of the + constitution to motions causable by these sensations being too dull or + too vivid. This susceptibility of the system to sensitive motions is + termed sensibility, to distinguish it from sensation, which is the actual + existence or exertion of pain or pleasure.</p> + + <p>Other classes of diseases are owing to the excessive promptitude, or + sluggishness of the constitution to voluntary exertions, as well as to + the quantity of desire or of aversion. This susceptibility of the system + to voluntary motions is termed voluntarity, to distinguish it from + volition, which is the exertion of desire or aversion; these diseases + will be treated of at length in the progress of the work.</p> + +<p class="center" style="margin-top: 2em;"><i>Association.</i></p> + + <p><a name="sect_XI_3">III</a>. <a name="sect_XI_3_1">1</a>. It is not + easy to assign a cause, why those animal movements, that have once + occurred in succession, or in combination, should afterwards have a + tendency to succeed or accompany each other. It is a property of + animation, and distinguishes this order of being from the other + productions of nature.</p> + + <p>When a child first wrote the word man, it was distinguished in his + mind into three letters, and those letters into many parts of letters; + but by repeated use the word man becomes to his hand in writing it, as to + his organs of speech in pronouncing it, but one movement without any + deliberation, or sensation, or irritation, interposed between the parts + of it. And as many separate motions of our muscles thus become united, + and form, as it were, one motion; so each separate motion before such + union may be conceived to consist of many parts or spaces moved through; + and perhaps even the individual fibres of our muscles have thus gradually + been brought to act in concert, which habits began to be acquired as + early as the very formation of the moving organs, long before the + nativity of the animal; as explained in the Section <a + href="#sect_XVI_2">XVI. 2</a>. on instinct.</p> + + <p><a name="sect_XI_3_2">2</a>. There are many motions of the body, + belonging to the irritative class, which might by a hasty observer be + mistaken for associated ones; as the peristaltic motion of the stomach + and intestines, and the contractions of the heart and arteries, might be + supposed to be associated with the irritative motions of their nerves of + sense, rather than to be excited by the irritation of their muscular + fibres by the distention, acrimony, or momentum of the blood. So the + distention or elongation of muscles by objects external to them irritates + them into contraction, though the cuticle or other parts may intervene + between the stimulating body and the contracting muscle. Thus a horse + voids his excrement when its weight or bulk irritates the rectum or + sphincter ani. These muscles act from the irritation of distention, when + he excludes his excrement, but the muscles of the abdomen and diaphragm + are brought into motion by association with those of the sphincter and + rectum.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XII">XII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF STIMULUS, SENSORIAL EXERTION, AND FIBROUS CONTRACTION.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XII_1">I</a>. Of fibrous contraction. <a + href="#sect_XII_1_1">1</a>. <i>Two particles of a fibre cannot approach + without the intervention of something, as in magnetism, electricity, + elasticity. Spirit of life is not electric ether. Galvani's + experiments.</i> <a href="#sect_XII_1_2">2</a>. <i>Contraction of a + fibre.</i> <a href="#sect_XII_1_3">3</a>. <i>Relaxation succeeds.</i> <a + href="#sect_XII_1_4">4</a>. <i>Successive contractions, with intervals. + Quick pulse from debility, from paucity of blood. Weak contractions + performed in less time, and with shorter intervals.</i> <a + href="#sect_XII_1_5">5</a>. <i>Last situation of the fibres continues + after contraction.</i> <a href="#sect_XII_1_6">6</a>. <i>Contraction + greater than usual induces pleasure or pain.</i> <a + href="#sect_XII_1_7">7</a>. <i>Mobility of the fibres uniform. Quantity + of sensorial power fluctuates. Constitutes excitability.</i> <a + href="#sect_XII_2">II</a>. Of sensorial exertion. <a + href="#sect_XII_2_1">1</a>. <i>Animal motion includes stimulus, sensorial + power, and contractile fibres. The sensorial faculties act separately or + conjointly. Stimulus of four kinds. Strength and weakness defined. + Sensorial power perpetually exhausted and renewed. Weakness from defect + of stimulus. From defect of sensorial power, the direct and indirect + debility of Dr. Brown. Why we become warm in Buxton bath after a time, + and see well after a time in a darkish room. Fibres may act violently, or + with their whole force, and yet feebly. Great exertion in inflammation + explained. Great muscular force of some insane people.</i> <a + href="#sect_XII_2_2">2</a>. <i>Occasional accumulation of sensorial power + in muscles subject to constant stimulus. In animals sleeping in winter. + In eggs, seeds, schirrous tumours, tendons, bones.</i> <a + href="#sect_XII_2_3">3</a>. <i>Great exertion introduces pleasure or + pain. Inflammation. Libration of the system between torpor and activity. + Fever-fits.</i> <a href="#sect_XII_2_4">4</a>. <i>Desire and aversion + introduced. Excess of volition cures fevers.</i> <a + href="#sect_XII_3">III</a>. Of repeated stimulus. <a + href="#sect_XII_3_1">1</a>. <i>A stimulus repeated too frequently looses + effect. As opium, wine, grief. Hence old age. Opium and aloes in small + doses.</i> <a href="#sect_XII_3_2">2</a>. <i>A stimulus not repeated too + frequently does not lose effect. Perpetual movement of the vital + organs.</i> <a href="#sect_XII_3_3">3</a>. <i>A stimulus repeated at + uniform times produces greater effect. Irritation combined with + association.</i> <a href="#sect_XII_3_4">4</a>. <i>A stimulus repeated + frequently and uniformly may be withdrawn, and the action of the organ + will continue. Hence the bark cures agues, and strengthens weak + constitutions.</i> <a href="#sect_XII_3_5">5</a>. <i>Defect of stimulus + repeated at certain intervals causes fever-fits.</i> <a + href="#sect_XII_3_6">6</a>. <i>Stimulus long applied ceases to act a + second time.</i> <a href="#sect_XII_3_7">7</a>. <i>If a stimulus excites + sensation in an organ not usually excited into sensation, inflammation is + produced.</i> <a href="#sect_XII_4">IV</a>. Of stimulus greater than + natural. <a href="#sect_XII_4_1">1</a>. <i>A stimulus greater than + natural diminishes the quantity of sensorial power in general.</i> <a + href="#sect_XII_4_2">2</a>. <i>In particular organs.</i> <a + href="#sect_XII_4_3">3</a>. <i>Induces the organ into spasmodic + actions.</i> <a href="#sect_XII_4_4">4</a>. <i>Induces the antagonist + fibres into action.</i> <a href="#sect_XII_4_5">5</a>. <i>Induces the + organ into convulsive or fixed spasms.</i> <a href="#sect_XII_4_6">6</a>. + <i>Produces paralysis of the organ.</i> <a href="#sect_XII_5">V</a>. Of + stimulus less than natural. <a href="#sect_XII_5_1">1</a>. <i>Stimulus + less than natural occasions accumulation of sensorial power in + general.</i> <a href="#sect_XII_5_2">2</a>. <i>In particular organs, + flushing of the face in a frosty morning. In fibres subject to perpetual + stimulus only. Quantity of sensorial power inversely as the stimulus.</i> + <a href="#sect_XII_5_3">3</a>. <i>Induces pain. As of cold, hunger, + head-ach.</i> <a href="#sect_XII_5_4">4</a>. <i>Induces more feeble and + frequent contraction. As in low fevers. Which are frequently owing to + deficiency of sensorial power rather than to deficiency of stimulus.</i> + <a href="#sect_XII_5_5">5</a>. <i>Inverts successive trains of motion. + Inverts ideas.</i> <a href="#sect_XII_5_6">6</a>. <i>Induces paralysis + and death.</i> <a href="#sect_XII_6">VI</a>. Cure of increased exertion. + <a href="#sect_XII_6_1">1</a>. <i>Natural cure of exhaustion of sensorial + power.</i> <a href="#sect_XII_6_2">2</a>. <i>Decrease the irritations. + Venesection. Cold. Abstinence.</i> <a href="#sect_XII_6_3">3</a>. + <i>Prevent the previous cold fit. Opium. Bark. Warmth. Anger. + Surprise.</i> <a href="#sect_XII_6_4">4</a>. <i>Excite some other part of + the system. Opium and warm bath relieve pains both from defect and from + excess of stimulus.</i> <a href="#sect_XII_6_5">5</a>. <i>First increase + the stimulus above, and then decrease it beneath the natural + quantity.</i> <a href="#sect_XII_7">VII</a>. Cure of decreased exertion. + <a href="#sect_XII_7_1">1</a>. <i>Natural cure by accumulation of + sensorial power. Ague-fits. Syncope.</i> <a href="#sect_XII_7_2">2</a>. + <i>Increase the stimulation, by wine, opium, given so as not to + intoxicate. Cheerful ideas.</i> <a href="#sect_XII_7_3">3</a>. <i>Change + the kinds of stimulus.</i> <a href="#sect_XII_7_4">4</a>. <i>Stimulate + the associated organs. Blisters of use in heart-burn, and cold + extremities.</i> <a href="#sect_XII_7_5">5</a>. <i>Decrease the + stimulation for a time, cold bath.</i> <a href="#sect_XII_7_6">6</a>. + <i>Decrease the stimulation below natural, and then increase it above + natural. Bark after emetics. Opium after venesection. Practice of + Sydenham in chlorosis.</i> <a href="#sect_XII_7_7">7</a>. <i>Prevent + unnecessary expenditure of sensorial power. Decumbent posture, silence, + darkness. Pulse quickened by rising out of bed.</i> <a + href="#sect_XII_7_8">8</a>. <i>To the greatest degree of quiescence apply + the least stimulus. Otherwise paralysis or inflammation of the organ + ensues. Gin, wine, blisters, destroy by too great stimulation in fevers + with debility. Intoxication in the slightest degree succeeded by + debility. Golden rule for determining the best degree of stimulus in low + fevers. Another golden rule for determining the quantity of spirit which + those, who are debilitated by drinking it, may safely omit.</i></p> + +</blockquote> + +<p class="center" style="margin-top: 2em;"><a name="sect_XII_1">I</a>. <i>Of fibrous contraction.</i></p> + + <p><a name="sect_XII_1_1">1</a>. If two particles of iron lie near each + other without motion, and afterwards approach each other; it is + reasonable to conclude that something besides the iron particles is the + cause of their approximation; this invisible something is termed + magnetism. In the same manner, if the particles, which compose an animal + muscle, do not touch each other in the relaxed state of the muscle, and + are brought into contact during the contraction of the muscle, it is + reasonable to conclude, that some other agent is the cause of this new + approximation. For nothing can act, where it does not exist; for to act + includes to exist; and therefore the particles of the muscular fibre + (which in its state of relaxation are supposed not to touch) cannot + affect each other without the influence of some intermediate agent; this + agent is here termed the spirit of animation, or sensorial power, but may + with equal propriety be termed the power, which causes contraction; or + may be called by any other name, which the reader may choose to affix to + it.</p> + + <p>The contraction of a muscular fibre may be compared to the following + electric experiment, which is here mentioned not as a philosophical + analogy, but as an illustration or simile to facilitate the conception of + a difficult subject. Let twenty very small Leyden phials properly coated + be hung in a row by fine silk threads at a small distance from each + other; let the internal charge of one phial be positive, and of the other + negative alternately, if a communication be made from the internal + surface of the first to the external surface of the last in the row, they + will all of them instantly approach each other, and thus shorten a line + that might connect them like a muscular fibre. See Botanic Garden, p. 1. + Canto I. 1. 202, note on Gymnotus.</p> + + <p>The attractions of electricity or of magnetism do not apply + philosophically to the illustration of the contraction of animal fibres, + since the force of those attractions increases in some proportion + inversely as the distance, but in muscular motion there appears no + difference in velocity or strength during the beginning or end of the + contraction, but what may be clearly ascribed to the varying mechanic + advantage in the approximation of one bone to another. Nor can muscular + motion be assimilated with greater plausibility to the attraction of + cohesion or elasticity; for in bending a steel spring, as a small sword, + a less force is required to bend it the first inch than the second; and + the second than the third; the particles of steel on the convex side of + the bent spring endeavouring to restore themselves more powerfully the + further they are drawn from each other. See Botanic Garden, P. I. addit. + Note XVIII.</p> + + <p>I am aware that this may be explained another way, by supposing the + elasticity of the spring to depend more on the compression of the + particles on the concave side than on the extension of them on the convex + side; and by supposing the elasticity of the elastic gum to depend more + on the resistance to the lateral compression of its particles than to the + longitudinal extension of them. Nevertheless in muscular contraction, as + above observed, there appears no difference in the velocity or force of + it at its commencement or at its termination; from whence we must + conclude that animal contraction is governed by laws of its own, and not + by those of mechanics, chemistry, magnetism, or electricity.</p> + + <p>On these accounts I do not think the experiments conclusive, which + were lately published by Galvani, Volta, and others, to shew a similitude + between the spirit of animation, which contracts the muscular fibres, and + the electric fluid. Since the electric fluid may act only as a more + potent stimulus exciting the muscular fibres into action, and not by + supplying them with a new quantity of the spirit of life. Thus in a + recent hemiplegia I have frequently observed, when the patient yawned and + stretched himself, that the paralytic limbs moved also, though they were + totally disobedient to the will. And when he was electrified by passing + shocks from the affected hand to the affected foot, a motion of the + paralytic limbs was also produced. Now as in the act of yawning the + muscles of the paralytic limbs were excited into action by the stimulus + of the irksomeness of a continued posture, and not by any additional + quantity of the spirit of life; so we may conclude, that the passage of + the electric fluid, which produced a similar effect, acted only as a + stimulus, and not by supplying any addition of sensorial power.</p> + + <p>If nevertheless this theory should ever become established, a stimulus + must be called an eductor of vital ether; which stimulus may consist of + sensation or volition, as in the electric eel, as well as in the appulses + of external bodies; and by drawing off the charges of vital fluid may + occasion the contraction or motions of the muscular fibres, and organs of + sense.</p> + + <p><a name="sect_XII_1_2">2</a>. The immediate effect of the action of + the spirit of animation or sensorial power on the fibrous parts of the + body, whether it acts in the mode of irritation, sensation, volition, or + association, is a contraction of the animal fibre, according to the + second law of animal causation. Sect. <a href="#sect_IV">IV</a>. Thus the + stimulus of the blood induces the contraction of the heart; the agreeable + taste of a strawberry produces the contraction of the muscles of + deglutition; the effort of the will contracts the muscles, which move the + limbs in walking; and by association other muscles of the trunk are + brought into contraction to preserve the balance of the body. The fibrous + extremities of the organs of sense have been shewn, by the ocular spectra + in Sect. <a href="#sect_III">III</a>. to suffer similar contraction by + each of the above modes of excitation; and by their configurations to + constitute our ideas.</p> + + <p><a name="sect_XII_1_3">3</a>. After animal fibres have for some time + been excited into contraction, a relaxation succeeds, even though the + exciting cause continues to act. In respect to the irritative motions + this is exemplified in the peristaltic contractions of the bowels; which + cease and are renewed alternately, though the stimulus of the aliment + continues to be uniformly applied; in the sensitive motions, as in + strangury, tenesmus, and parturition, the alternate contractions and + relaxations of the muscles exist, though the stimulus is perpetual. In + our voluntary exertions it is experienced, as no one can hang long by the + hands, however vehemently he wills so to do; and in the associate motions + the constant change of our attitudes evinces the necessity of relaxation + to those muscles, which have been long in action.</p> + + <p>This relaxation of a muscle after its contraction, even though the + stimulus continues to be applied, appears to arise from the expenditure + or diminution of the spirit of animation previously resident in the + muscle, according to the second law of animal causation in Sect. <a + href="#sect_IV">IV</a>. In those constitutions, which are termed weak, + the spirit of animation becomes sooner exhausted, and tremulous motions + are produced, as in the hands of infirm people, when they lift a cup to + their mouths. This quicker exhaustion of the spirit of animation is + probably owing to a less quantity of it residing in the acting fibres, + which therefore more frequently require a supply from the nerves, which + belong to them.</p> + + <p><a name="sect_XII_1_4">4</a>. If the sensorial power continues to act, + whether it acts in the mode of irritation, sensation, volition, or + association, a new contraction of the animal fibre succeeds after a + certain interval; which interval is of shorter continuance in weak people + than in strong ones. This is exemplified in the shaking of the hands of + weak people, when they attempt to write. In a manuscript epistle of one + of my correspondents, which is written in a small hand, I observed from + four to six zigzags in the perpendicular stroke of every letter, which + shews that both the contractions of the fingers, and intervals between + them, must have been performed in very short periods of time.</p> + + <p>The times of contraction of the muscles of enfeebled people being + less, and the intervals between those contractions being less also, + accounts for the quick pulse in fevers with debility, and in dying + animals. The shortness of the intervals between one contraction and + another in weak constitutions, is probably owing to the general + deficiency of the quantity of the spirit of animation, and that therefore + there is a less quantity of it to be received at each interval of the + activity of the fibres. Hence in repeated motions, as of the fingers in + performing on the harpsichord, it would at first sight appear, that + swiftness and strength were incompatible; nevertheless the single + contraction of a muscle is performed with greater velocity as well as + with greater force by vigorous constitutions, as in throwing a + javelin.</p> + + <p>There is however another circumstance, which may often contribute to + cause the quickness of the pulse in nervous fevers, as in animals + bleeding to death in the slaughter-house; which is the deficient quantity + of blood; whence the heart is but half distended, and in consequence + sooner contracts. See Sect. <a href="#sect_XXXII_2_1">XXXII. 2. + 1</a>.</p> + + <p>For we must not confound frequency of repetition with quickness of + motion, or the number of pulsations with the velocity, with which the + fibres, which constitute the coats of the arteries, contract themselves. + For where the frequency of the pulsations is but seventy-five in a + minute, as in health; the contracting fibres, which constitute the sides + of the arteries, may move through a greater space in a given time, than + where the frequency of pulsation is one hundred and fifty in a minute, as + in some fevers with great debility. For if in those fevers the arteries + do not expand themselves in their diastole to more than half the usual + diameter of their diastole in health, the fibres which constitute their + coats, will move through a less space in a minute than in health, though + they make two pulsations for one.</p> + + <p>Suppose the diameter of the artery during its systole to be one line, + and that the diameter of the same artery during its diastole is in health + is 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 space of nine lines in length. + While the arterial fibres in the fever with debility would twice contract + from a circle of six lines to a circle of three lines; that is while they + move through a space equal to six lines. Hence though the frequency of + pulsation in fever be greater as two to one, yet the velocity of + contraction in health is greater as nine to six, or as three to two.</p> + + <p>On the contrary in inflammatory diseases with strength, as in the + pleurisy, the velocity of the contracting sides of the arteries is much + greater than in health, for if we suppose the number of pulsations in a + pleurisy 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 diseases) and if the diameter of the artery in diastole be + one third greater than in health, which I believe is near the truth, the + result will be, that the velocity of the contractile sides of the + arteries will be in a pleurisy as two and a half to one, compared to the + velocity of their contraction in a state of health, for if the + circumference of the systole of the artery be three lines, and the + diastole in health be twelve lines in circumference, and in a pleurisy + eighteen lines; and secondly, if the artery pulsates thrice in the + diseased state for twice in the healthy one, it follows, that the + velocity of contraction in the diseased state to that in the healthy + state will be forty-five to eighteen, or as two and a half to one.</p> + + <p>From hence it would appear, that if we had a criterion to determine + the velocity of the arterial contractions, it would at the same time give + us their strength, and thus be of more service in distinguishing + diseases, than the knowledge of their frequency. As such a criterion + cannot be had, the frequency of pulsation, the age of the patient being + allowed for, will in some measure assist us to distinguish arterial + strength from arterial debility, since in inflammatory diseases with + strength the frequency seldom exceeds one hundred and eighteen or one + hundred and twenty pulsations in a minute; unless under peculiar + circumstance, as the great additional stimuli of wine or of external + heat.</p> + + <p><a name="sect_XII_1_5">5</a>. After a muscle or organ of sense has + been excited into contraction, and the sensorial power ceases to act, the + last situation or configuration of it continues; unless it be disturbed + by the action of some antagonist fibres, or other extraneous power. Thus + in weak or languid people, wherever they throw their limbs on their bed + or sofa, there they lie, till another exertion changes their attitude; + hence one kind of ocular spectra seems to be produced after looking at + bright objects; thus when a fire-stick 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 ceasing before the return of + the whirling fire.</p> + + <p>Thus if any one looks at the setting sun for a short time, and then + covers his closed eyes with his hand, he will for many seconds of time + perceive the image of the sun on his retina. A similar image of all other + bodies would remain some 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. <a href="#sect_XVIII_5">XVIII. 5</a>. on Sleep. + Hence the dark spots, and other ocular spectra, are more frequently + attended to, and remain longer in the eyes of weak people, as after + violent exercise, intoxication, or want of sleep.</p> + + <p><a name="sect_XII_1_6">6</a>. A contraction of the fibres somewhat + greater than usual introduces pleasurable sensation into the system, + according to the fourth law of animal causation. Hence the pleasure in + the beginning of drunkenness is owing to the increased action of the + system from the stimulus of vinous spirit or of opium. If the + contractions be still greater in energy or duration, painful sensations + are introduced, as in consequence of great heat, or caustic applications, + or fatigue.</p> + + <p>If any part of the system, which is used to perpetual activity, as the + stomach, or heart, or the fine vessels of the skin, acts for a time with + less energy, another kind of painful sensation ensues, which is called + hunger, or faintness, or cold. This occurs in a less degree in the + locomotive muscles, and is called wearysomeness. In the two former kinds + of sensation there is an expenditure of sensorial power, in these latter + there is an accumulation of it.</p> + + <p><a name="sect_XII_1_7">7</a>. We have used the words exertion of + sensorial power as a general term to express either irritation, + sensation, volition, or association; that is, to express the activity or + motion of the spirit of animation, at the time it produces the + contractions of the fibrous parts of the system. It may be supposed that + there may exist a greater or less mobility of the fibrous parts of our + system, or a propensity to be stimulated into contraction by the greater + or less quantity or energy of the spirit of animation; and that hence if + the exertion of the sensorial power be in its natural state, and the + mobility of the fibres be increased, the same quantity of fibrous + contraction will be caused, as if the mobility of the fibres continues in + its natural state, and the sensorial exertion be increased.</p> + + <p>Thus it may be conceived, that in diseases accompanied with strength, + as in inflammatory fevers with arterial strength, that the cause of + greater fibrous contraction, may exist in the increased mobility of the + fibres, whose contractions are thence both more forceable and more + frequent. And that in diseases attended with debility, as in nervous + fevers, where the fibrous contractions are weaker, and more frequent, it + may be conceived that the cause consists in a decrease of mobility of the + fibres; and that those weak constitutions, which are attended with cold + extremities and large pupils of the eyes, may possess less mobility of + the contractile fibres, as well as less quantity of exertion of the + spirit of animation.</p> + + <p>In answer to this mode of reasoning it may be sufficient to observe, + that the contractile fibres consist of inert matter, and when the + sensorial power is withdrawn, as in death, they possess no power of + motion at all, but remain in their last state, whether of contraction or + relaxation, and must thence derive the whole of this property from the + spirit of animation. At the same time it is not improbable, that the + moving fibres of strong people may possess a capability of receiving or + containing a greater quantity of the spirit of animation than those of + weak people.</p> + + <p>In every contraction of a fibre there is an expenditure of the + sensorial power, or spirit of animation; and where the exertion of this + sensorial power has been for some time increased, and the muscles or + organs of sense have in consequence acted with greater energy, its + propensity to activity is proportionally lessened; which is to be + ascribed to the exhaustion or diminution of its quantity. On the + contrary, where there has been less fibrous contraction than usual for a + certain time, the sensorial power or spirit of animation becomes + accumulated in the inactive part of the system. Hence vigour succeeds + rest, and hence the propensity to action of all our organs of sense and + muscles is in a state of perpetual fluctuation. The irritability for + instance of the retina, that is, its quantity of sensorial power, varies + every moment according to the brightness or obscurity of the object last + beheld compared with the present one. The same occurs to our sense of + heat, and to every part of our system, which is capable of being excited + into action.</p> + + <p>When this variation of the exertion of the sensorial power becomes + much and permanently above or beneath the natural quantity, it becomes a + disease. If the irritative motions be too great or too little, it shews + that the stimulus of external things affect this sensorial power too + violently or too inertly. If the sensitive motions be too great or too + little, the cause arises from the deficient or exuberant quantity of + sensation produced in consequence of the motions of the muscular fibres + or organs of sense; if the voluntary actions are diseased the cause is to + be looked for in the quantity of volition produced in consequence of the + desire or aversion occasioned by the painful or pleasurable sensations + above mentioned. And the diseases of associations probably depend on the + greater or less quantity of the other three sensorial powers by which + they were formed.</p> + + <p>From whence it appears that the propensity to action, whether it be + called irritability, sensibility, voluntarity, or associability, is only + another mode of expression for the quantity of sensorial power residing + in the organ to be excited. And that on the contrary the words + inirritability and insensibility, together with inaptitude to voluntary + and associate motions, are synonymous with deficiency of the quantity of + sensorial power, or of the spirit of animation, residing in the organs to + be excited.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XII_2">II</a>. <i>Of sensorial Exertion.</i></p> + + <p><a name="sect_XII_2_1">1</a>. There are three circumstances to be + attended to in the production of animal motions, 1st. The stimulus. 2d. + The sensorial power. 3d. The contractile fibre. 1st. A stimulus, external + to the organ, originally induces into action the sensorial faculty termed + irritation; this produces the contraction of the fibres, which, if it be + perceived at all, introduces pleasure or pain; which in their active + state are termed sensation; which is another sensorial faculty, and + occasionally produces contraction of the fibres; this pleasure or pain is + therefore to be considered as another stimulus, which may either act + alone or in conjunction with the former faculty of the sensorium termed + irritation.</p> + + <p>This new stimulus of pleasure or pain either induces into action the + sensorial faculty termed sensation, which then produces the contraction + of the fibres; or it introduces desire or aversion, which excite into + action another sensorial faculty, termed volition, and may therefore be + considered as another stimulus, which either alone or in conjunction with + one or both of the two former faculties of the sensorium produces the + contraction of animal fibres. There is another sensorial power, that of + association, which perpetually, in conjunction with one or more of the + above, and frequently singly, produces the contraction of animal fibres, + and which is itself excited into action by the previous motions of + contracting fibres.</p> + + <p>Now as the sensorial power, termed irritation, residing in any + particular fibres, is excited into exertion by the stimulus of external + bodies acting on those fibres; the sensorial power, termed sensation, + residing in any particular fibres is excited into exertion by the + stimulus of pleasure or pain acting on those fibres; the sensorial power, + termed volition, residing in any particular fibres is excited into + exertion by the stimulus of desire or aversion; and the sensorial power, + termed association, residing in any particular fibres, is excited into + action by the stimulus of other fibrous motions, which had frequently + preceded them. The word stimulus may therefore be used without + impropriety of language, for any of these four causes, which excite the + four sensorial powers into exertion. For though the immediate cause of + volition has generally been termed <i>a motive</i>; and that of + irritation only has generally obtained the name of <i>stimulus</i>; yet + as the immediate cause, which excites the sensorial powers of sensation, + or of association into exertion, have obtained no general name, we shall + use the word stimulus for them all.</p> + + <p>Hence the quantity of motion produced in any particular part of the + animal system will be as the quantity of stimulus and the quantity of + sensorial power, or spirit of animation, residing in the contracting + fibres. Where both these quantities are great, <i>strength</i> is + produced, when that word is applied to the motions of animal bodies. + Where either of them is deficient, <i>weakness</i> is produced, as + applied to the motions of animal bodies.</p> + + <p>Now as the sensorial power, or spirit of animation, is perpetually + exhausted by the expenditure of it in fibrous contractions, and is + perpetually renewed by the secretion or production of it in the brain and + spinal marrow, the quantity of animal strength must be in a perpetual + state of fluctuation on this account; and if to this be added the + unceasing variation of all the four kinds of stimulus above described, + which produce the exertions of the sensorial powers, the ceaseless + vicissitude of animal strength becomes easily comprehended.</p> + + <p>If the quantity of sensorial power remains the same, and the quantity + of stimulus be lessened, a weakness of the fibrous contractions ensues, + which may be denominated <i>debility from defect of stimulus</i>. If the + quantity of stimulus remains the same, and the quantity of sensorial + power be lessened, another kind of weakness ensues, which may be termed + <i>debility from defect of sensorial power</i>; the former of these is + called by Dr. Brown, in his Elements of Medicine, direct debility, and + the latter indirect debility. The coincidence of some parts of this work + with correspondent deductions in the Brunonian Elementa Medicina, a work + (with some exceptions) of great genius, must be considered as + confirmations of the truth of the theory, as they were probably arrived + at by different trains of reasoning.</p> + + <p>Thus in those who have been exposed to cold and hunger there is a + deficiency of stimulus. While in nervous fever there is a deficiency of + sensorial power. And in habitual drunkards, in a morning before their + usual potation, there is a deficiency both of stimulus and of sensorial + power. While, on the other hand, in the beginning of intoxication there + is an excess of stimulus; in the hot-ach, after the hands have been + immersed in snow, there is a redundancy of sensorial power; and in + inflammatory diseases with arterial strength, there is an excess of + both.</p> + + <p>Hence if the sensorial power be lessened, while the quantity of + stimulus remains the same as in nervous fever, the frequency of + repetition of the arterial contractions may continue, but their force in + respect to removing obstacles, as in promoting the circulation of the + blood, or the velocity of each contraction, will be diminished, that is, + the animal strength will be lessened. And secondly, if the quantity of + sensorial power be lessened, and the stimulus be increased to a certain + degree, as in giving opium in nervous fevers, the arterial contractions + may be performed more frequently than natural, yet with less + strength.</p> + + <p>And thirdly, if the sensorial power continues the same in respect to + quantity, and the stimulus be somewhat diminished, as in going into a + darkish room, or into a coldish bath, suppose of about eighty degrees of + heat, as Buxton-bath, a temporary weakness of the affected fibres is + induced, till an accumulation of sensorial power gradually succeeds, and + counterbalances the deficiency of stimulus, and then the bath ceases to + feel cold, and the room ceases to appear dark; because the fibres of the + subcutaneous vessels, or of the organs of sense, act with their usual + energy.</p> + + <p>A set of muscular fibres may thus be stimulated into violent exertion, + that is, they may act frequently, and with their whole sensorial power, + but may nevertheless not act strongly; because the quantity of their + sensorial power was originally small, or was previously exhausted. Hence + a stimulus may be great, and the irritation in consequence act with its + full force, as in the hot paroxysms of nervous fever; but if the + sensorial power, termed irritation, be small in quantity, the force of + the fibrous contractions, and the times of their continuance in their + contracted state, will be proportionally small.</p> + + <p>In the same manner in the hot paroxysm of putrid fevers, which are + shewn in Sect. <a href="#sect_XXXIII">XXXIII</a>. to be inflammatory + fevers with arterial debility, the sensorial power termed sensation is + exerted with great activity, yet the fibrous contractions, which produce + the circulation of the blood, are performed without strength, because the + quantity of sensorial power then residing in that part of the system is + small.</p> + + <p>Thus in irritative fever with arterial strength, that is, with excess + of spirit of animation, the quantity of exertion during the hot part of + the paroxysm is to be estimated from the quantity of stimulus, and the + quantity of sensorial power. While in sensitive (or inflammatory) fever + with arterial strength, that is, with excess of spirit of animation, the + violent and forcible actions of the vascular system during the hot part + of the paroxysm are induced by the exertions of two sensorial powers, + which are excited by two kinds of stimulus. These are the sensorial power + of irritation excited by the stimulus of bodies external to the moving + fibres, and the sensorial power of sensation excited by the pain in + consequence of the increased contractions of those moving fibres.</p> + + <p>And in insane people in some cases the force of their muscular actions + will be in proportion to the quantity of sensorial power, which they + possess, and the quantity of the stimulus of desire or aversion, which + excites their volition into action. At the same time in other cases the + stimulus of pain or pleasure, and the stimulus of external bodies, may + excite into action the sensorial powers of sensation and irritation, and + thus add greater force to their muscular actions.</p> + + <p><a name="sect_XII_2_2">2</a>. The application of the stimulus, whether + that stimulus be some quality of external bodies, or pleasure or pain, or + desire or aversion, or a link of association, excites the correspondent + sensorial power into action, and this causes the contraction of the + fibre. On the contraction of the fibre a part of the spirit of animation + becomes expended, and the fibre ceases to contract, though the stimulus + continues to be applied; till in a certain time the fibre having received + a supply of sensorial power is ready to contract again, if the stimulus + continues to be applied. If the stimulus on the contrary be withdrawn, + the same quantity of quiescent sensorial power becomes resident in the + fibre as before its contraction; as appears from the readiness for action + of the large locomotive muscles of the body in a short time after common + exertion.</p> + + <p>But in those muscular fibres, which are subject to constant stimulus, + as the arteries, glands, and capillary vessels, another phenomenon + occurs, if their accustomed stimulus be withdrawn; which is, that the + sensorial power becomes accumulated in the contractile fibres, owing to + the want of its being perpetually expended, or carried away, by their + usual unremitted contractions. And on this account those muscular fibres + become afterwards excitable into their natural actions by a much weaker + stimulus; or into unnatural violence of action by their accustomed + stimulus, as is seen in the hot fits of intermittent fevers, which are in + consequence of the previous cold ones. Thus the minute vessels of the + skin are constantly stimulated by the fluid matter of heat; if the + quantity of this stimulus of heat be a while diminished, as in covering + the hands with snow, the vessels cease to act, as appears from the + paleness of the skin; if this cold application of snow be continued but a + short time, the sensorial power, which had habitually been supplied to + the fibres, becomes now accumulated in them, owing to the want of its + being expended by their accustomed contractions. And thence a less + stimulus of heat will now excite them into violent contractions.</p> + + <p>If the quiescence of fibres, which had previously been subject to + perpetual stimulus, continues a longer time; or their accustomed stimulus + be more completely withdrawn; the accumulation of sensorial power becomes + still greater, as in those exposed to cold and hunger; pain is produced, + and the organ gradually dies from the chemical changes, which take place + in it; or it is at a great distance of time restored to action by + stimulus applied with great caution in small quantity, as happens to some + larger animals and to many insects, which during the winter months lie + benumbed with cold, and are said to sleep, and to persons apparently + drowned, or apparently frozen to death. Snails have been said to revive + by throwing them into water after having been many years shut up in the + cabinets of the curious; and eggs and seeds in general are restored to + life after many months of torpor by the stimulus of warmth and + moisture.</p> + + <p>The inflammation of schirrous tumours, which have long existed in a + state of inaction, is a process of this kind; as well as the sensibility + acquired by inflamed tendons and bones, which had at their formation a + similar sensibility, which had so long lain dormant in their uninflamed + state.</p> + + <p><a name="sect_XII_2_3">3</a>. If after long quiescence from defect of + stimulus the fibres, which had previously been habituated to perpetual + stimulus, are again exposed to but their usual quantity of it; as in + those who have suffered the extremes of cold or hunger; a violent + exertion of the affected organ commences, owing, as above explained, to + the great accumulation of sensorial power. This violent exertion not only + diminishes the accumulated spirit of animation, but at the same time + induces pleasure or pain into the system, which, whether it be succeeded + by inflammation or not, becomes an additional stimulus, and acting along + with the former one, produces still greater exertions; and thus reduces + the sensorial power in the contracting fibres beneath its natural + quantity.</p> + + <p>When the spirit of animation is thus exhausted by useless exertions, + the organ becomes torpid or unexcitable into action, and a second fit of + quiescence succeeds that of abundant activity. During this second fit of + quiescence the sensorial power becomes again accumulated, and another fit + of exertion follows in train. These vicissitudes of exertion and inertion + of the arterial system constitute the paroxysms of remittent fevers; or + intermittent ones, when there is an interval of the natural action of the + arteries between the exacerbations.</p> + + <p>In these paroxysms of fevers, which consist of the libration of the + arterial system between the extremes of exertion and quiescence, either + the fits become less and less violent from the contractile fibres + becoming coming less excitable to the stimulus by habit, that is, by + becoming accustomed to it, as explained below <a + href="#sect_XII_3_1">XII. 3. 1</a>. or the whole sensorial power becomes + exhausted, and the arteries cease to beat, and the patient dies in the + cold part of the paroxysm. Or secondly, so much pain is introduced into + the system by the violent contractions of the fibres, that inflammation + arises, which prevents future cold fits by expending a part of the + sensorial power in the extension of old vessels or the production of new + ones; and thus preventing the too great accumulation or exertion of it in + other parts of the system; or which by the great increase of stimulus + excites into great action the whole glandular system as well as the + arterial, and thence a greater quantity of sensorial power is produced in + the brain, and thus its exhaustion in any peculiar part of the system + ceases to be affected.</p> + + <p><a name="sect_XII_2_4">4</a>. Or thirdly, in consequence of the + painful or pleasurable sensation above mentioned, desire and aversion are + introduced, and inordinate volition succeeds; which by its own exertions + expends so much of the spirit of animation, that the two other sensorial + faculties, or irritation and sensation, act so much more feebly; that the + paroxysms of fever, or that libration between the extremes of exertion + and inactivity of the arterial system, gradually subsides. On this + account a temporary insanity is a favourable sign in fevers, as I have + had some opportunities of observing.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XII_3">III</a>. <i>Of repeated Stimulus.</i></p> + + <p><a name="sect_XII_3_1">1</a>. When a stimulus is repeated more + frequently than the expenditure of sensorial power can be renewed in the + acting organ, the effect of the stimulus becomes gradually diminished. + Thus if two grains of opium be swallowed by a person unused to so strong + a stimulus, all the vascular systems in the body act with greater energy, + all the secretions and the absorption from those secreted fluids are + increased in quantity; and pleasure or pain are introduced into the + system, which adds an additional stimulus to that already too great. + After some hours the sensorial power becomes diminished in quantity, + expended by the great activity of the system; and thence, when the + stimulus of the opium is withdrawn, the fibres will not obey their usual + degree of natural stimulus, and a consequent torpor or quiescence + succeeds, as is experienced by drunkards, who on the day after a great + excess of spirituous potation feel indigestion, head-ach, and general + debility.</p> + + <p>In this fit of torpor or quiescence of a part or of the whole of the + system, an accumulation of the sensorial power in the affected fibres is + formed, and occasions a second paroxysm of exertion by the application + only of the natural stimulus, and thus a libration of the sensorial + exertion between one excess and the other continues for two or three + days, where the stimulus was violent in degree; and for weeks in some + fevers, from the stimulus of contagious matter.</p> + + <p>But if a second dose of opium be exhibited before the fibres have + regained their natural quantity of sensorial power, its effect will be + much less than the former, because the spirit of animation or sensorial + power is in part exhausted by the previous excess of exertion. Hence all + medicines repeated too frequently gradually lose their effect, as opium + and wine. Many things of disagreeable taste at first cease to be + disagreeable by frequent repetition, as tobacco; grief and pain gradually + diminish, and at length cease altogether, and hence life itself becomes + tolerable.</p> + + <p>Besides the temporary diminution of the spirit of animation or + sensorial power, which is naturally stationary or resident in every + living fibre, by a single exhibition of a powerful stimulus, the + contractile fibres themselves, by the perpetual application of a new + quantity of stimulus, before they have regained their natural quantity of + sensorial power, appear to suffer in their capability of receiving so + much as the natural quantity of sensorial power; and hence a permanent + deficiency of spirit of animation takes place, however long the stimulus + may have been withdrawn. On this cause depends the permanent debility of + those, who have been addicted to intoxication, the general weakness of + old age, and the natural debility or inirritability of those, who have + pale skins and large pupils of their eyes.</p> + + <p>There is a curious phenomenon belongs to this place, which has always + appeared difficult of solution; and that is, that opium or aloes may be + exhibited in small doses at first, and gradually increased to very large + ones without producing stupor or diarrhœa. In this case, though the + opium and aloes are given in such small doses as not to produce + intoxication or catharsis, yet they are exhibited in quantities + sufficient in some degree to exhaust the sensorial power, and hence a + stronger and a stronger dose is required; otherwise the medicine would + soon cease to act at all.</p> + + <p>On the contrary, if the opium or aloes be exhibited in a large dose at + first, so as to produce intoxication or diarrhœa; after a few + repetitions the quantity of either of them may be diminished, and they + will still produce this effect. For the more powerful stimulus dissevers + the progressive catenations of animal motions, described in Sect. <a + href="#sect_XVII">XVII</a>. and introduces a new link between them; + whence every repetition strengthens this new association or catenation, + and the stimulus may be gradually decreased, or be nearly withdrawn, and + yet the effect shall continue; because the sensorial power of association + or catenation being united with the stimulus, increases in energy with + every repetition of the catenated circle; and it is by these means that + all the irritative associations of motions are originally produced.</p> + + <p><a name="sect_XII_3_2">2</a>. When a stimulus is repeated at such + distant intervals of time, that the natural quantity of sensorial power + becomes completely restored in the acting fibres, it will act with the + same energy as when first applied. Hence those who have lately accustomed + themselves to large doses of opium by beginning with small ones, and + gradually increasing them, and repeating them frequently, as mentioned in + the preceding paragraph; if they intermit the use of it for a few days + only, must begin again with as small doses as they took at first, + otherwise they will experience the inconveniences of intoxication.</p> + + <p>On this circumstance depend the constant unfailing effects of the + various kinds of stimulus, which excite into action all the vascular + systems in the body; the arterial, venous, absorbent, and glandular + vessels, are brought into perpetual unwearied action by the fluids, which + are adapted to stimulate them; but these have the sensorial power of + association added to that of irritation, and even in some degree that of + sensation, and even of volition, as will be spoken of in their places; + and life itself is thus carried on by the production of sensorial power + being equal to its waste or expenditure in the perpetual movement of the + vascular organization.</p> + + <p><a name="sect_XII_3_3">3</a>. When a stimulus is repeated at uniform + intervals of time with such distances between them, that the expenditure + of sensorial power in the acting fibres becomes completely renewed, the + effect is produced with greater facility or energy. For the sensorial + power of association is combined with the sensorial power of irritation, + or, in common language, the acquired habit assists the power of the + stimulus.</p> + + <p>This circumstance not only obtains in the annual and diurnal + catenations of animal motions explained in Sect. <a + href="#sect_XXXVI">XXXVI</a>. but in every less circle of actions or + ideas, as in the burthen of a song, or the iterations of a dance; and + constitutes the pleasure we receive from repetition and imitation; as + treated of in Sect. <a href="#sect_XXII_2">XXII. 2</a>.</p> + + <p><a name="sect_XII_3_4">4</a>. When a stimulus has been many times + repeated at uniform intervals, so as to produce the complete action of + the organ, it may then be gradually diminished, or totally withdrawn, and + the action of the organ will continue. For the sensorial power of + association becomes united with that of irritation, and by frequent + repetition becomes at length of sufficient energy to carry on the new + link in the circle of actions, without the irritation which at first + introduced it.</p> + + <p>Hence, when the bark is given at stated intervals for the cure of + intermittent fevers, if sixty grains of it be given every three hours for + the twenty-four hours preceding the expected paroxysm, so as to stimulate + the defective part of the system into action, and by that means to + prevent the torpor or quiescence of the fibres, which constitutes the + cold fit; much less than half the quantity, given before the time at + which another paroxysm of quiescence would have taken place, will be + sufficient to prevent it; because now the sensorial power, termed + association, acts in a twofold manner. First, in respect to the period of + the catenation in which the cold fit was produced, which is now + dissevered by the stronger stimulus of the first doses of the bark; and, + secondly, because each dose of bark being repeated at periodical times, + has its effect increased by the sensorial faculty of association being + combined with that of irritation.</p> + + <p>Now, when sixty grains of Peruvian bark are taken twice a day, suppose + at ten o'clock and at six, for a fortnight, the irritation excited by + this additional stimulus becomes a part of the diurnal circle of actions, + and will at length carry on the increased action of the system without + the assistance of the stimulus of the bark. On this theory the bitter + medicines, chalybeates, and opiates in appropriated doses, exhibited for + a fortnight, give permanent strength to pale feeble children, and other + weak constitutions.</p> + + <p><a name="sect_XII_3_5">5</a>. When a defect of stimulus, as of heat, + recurs at certain diurnal intervals, which induces some torpor or + quiescence of a part of the system, the diurnal catenation of actions + becomes disordered, and a new association with this link of torpid action + is formed; on the next period the quantity of quiescence will be + increased, suppose the same defect of stimulus to recur, because now the + new association conspires with the defective irritation in introducing + the torpid action of this part of the diurnal catenation. In this manner + many fever-fits commence, where the patient is for some days indisposed + at certain hours, before the cold paroxysm of fever is completely formed. + See Sect. <a href="#sect_XVII_3_3">XVII. 3. 3</a>. on Catenation of + Animal Motions.</p> + + <p><a name="sect_XII_3_6">6</a>. If a stimulus, which at first excited + the affected organ into so great exertion as to produce sensation, be + continued for a certain time, it will cease to produce sensation both + then and when repeated, though the irritative motions in consequence of + it may continue or be re-excited.</p> + + <p>Many catenations of irritative motions were at first succeeded by + sensation, as the apparent motions of objects when we walk past them, and + probably the vital motions themselves in the early state of our + existence. But as those sensations were followed by no movements of the + system in consequence of them, they gradually ceased to be produced, not + being joined to any succeeding link of catenation. Hence contagious + matter, which has for some weeks stimulated the system into great and + permanent sensation, ceases afterwards to produce general sensation, or + inflammation, though it may still induce topical irritations. See Sect. + <a href="#sect_XXXIII_2_8">XXXIII. 2. 8</a>. <a href="#sect_XIX_9">XIX. + 9</a>.</p> + + <p>Our absorbent system then seems to receive those contagious matters, + which it has before experienced, in the same manner as it imbibes common + moisture or other fluids; that is, without being thrown into so violent + action as to produce sensation; the consequence of which is an increase + of daily energy or activity, till inflammation and its consequences + succeed.</p> + + <p><a name="sect_XII_3_7">7</a>. If a stimulus excites an organ into such + violent contractions as to produce sensation, the motions of which organ + had not usually produced sensation, this new sensorial power, added to + the irritation occasioned by the stimulus, increases the activity of the + organ. And if this activity be catenated with the diurnal circle of + actions, an increasing inflammation is produced; as in the evening + paroxysms of small-pox, and other fevers with inflammation. And hence + schirrous tumours, tendons and membranes, and probably the arteries + themselves become inflamed, when they are strongly stimulated.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XII_4">IV</a>. <i>Of Stimulus greater than natural.</i></p> + + <p><a name="sect_XII_4_1">1</a>. A quantity of stimulus greater than + natural, producing an increased exertion of sensorial power, whether that + exertion be in the mode of irritation, sensation, volition, or + association, diminishes the general quantity of it. This fact is + observable in the progress of intoxication, as the increased quantity or + energy of the irritative motions, owing to the stimulus of vinous spirit, + introduces much pleasurable sensation into the system, and much exertion + of muscular or sensual motions in consequence of this increased + sensation; the voluntary motions, and even the associate ones, become + much impaired or diminished; and delirium and staggering succeed. See + Sect. <a href="#sect_XXI">XXI</a>. on Drunkenness. And hence the great + prostration of the strength of the locomotive muscles in some fevers, is + owing to the exhaustion of sensorial power by the increased action of the + arterial system.</p> + + <p>In like manner a stimulus greater than natural, applied to a part of + the system, increases the exertion of sensorial power in that part, and + diminishes it in some other part. As in the commencement of scarlet + fever, it is usual to see great redness and heat on the faces and breasts + of children, while at the same time their feet are colder than natural; + partial heats are observable in other fevers with debility, and are + generally attended with torpor or quiescence of some other part of the + system. But these partial exertions of sensorial power are sometimes + attended with increased partial exertions in other parts of the system, + which sympathize with them, as the flushing of the face after a full + meal. Both these therefore are to be ascribed to sympathetic + associations, explained in Sect. <a href="#sect_XXXV">XXXV</a>. and not + to general exhaustion or accumulation of sensorial power.</p> + + <p><a name="sect_XII_4_2">2</a>. A quantity of stimulus greater than + natural, producing an increased exertion of sensorial power in any + particular organ, diminishes the quantity of it in that organ. This + appears from the contractions of animal fibres being not so easily + excited by a less stimulus after the organ has been subjected to a + greater. Thus after looking at any luminous object of a small size, as at + the setting sun, for a short time, so as not much to fatigue the eye, + this part of the retina becomes less sensible to smaller quantities of + light; hence when the eyes are turned on other less luminous parts of the + sky, a dark spot is seen resembling the shape of the sun, or other + luminous object which we last behold. See Sect. <a href="#sect_XL_2">XL. + No. 2</a>.</p> + + <p>Thus we are some time before we can distinguish objects in an obscure + room after coming from bright day-light, though the iris presently + contracts itself. We are not able to hear weak sounds after loud ones. + And the stomachs of those who have been much habituated to the stronger + stimulus of fermented or spirituous liquors, are not excited into due + action by weaker ones.</p> + + <p><a name="sect_XII_4_3">3</a>. A quantity of stimulus something greater + than the last mentioned, or longer continued, induces the organ into + spasmodic action, which ceases and recurs alternately. Thus on looking + for a time on the setting sun, so as not greatly to fatigue the sight, a + yellow spectrum is seen when the eyes are closed and covered, which + continues for a time, and then disappears and recurs repeatedly before it + entirely vanishes. See Sect. <a href="#sect_XL_5">XL. No. 5</a>. Thus the + action of vomiting ceases and is renewed by intervals, although the + emetic drug is thrown up with the first effort. A tenesmus continues by + intervals some time after the exclusion of acrid excrement; and the + pulsations of the heart of a viper are said to continue some time after + it is cleared from its blood.</p> + + <p>In these cases 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 renewed, and again induces + contractions of the fibres with gradually diminishing effect.</p> + + <p><a name="sect_XII_4_4">4</a>. A quantity of stimulus greater than that + last mentioned, or longer continued, induces the antagonist muscles into + spasmodic action. This is beautifully illustrated by the ocular spectra + described in Sect. <a href="#sect_XL_6">XL. No. 6</a>. to which the + reader is referred. From those experiments there is reason to conclude + that the fatigued part of the retina throws itself into a contrary mode + of action like oscitation or pandiculation, as soon as the stimulus, + which has fatigued it, is withdrawn; but that it still remains liable to + be excited into action by any other colours except the colour with which + it has been fatigued. Thus the yawning and stretching the limbs after a + continued action or attitude seems occasioned by the antagonist muscles + being stimulated by their extension during the contractions of those in + action, or in the situation in which that action last left them.</p> + + <p><a name="sect_XII_4_5">5</a>. A quantity of stimulus greater than the + last, or longer continued, induces variety of convulsions or fixed spasms + either of the affected organ or of the moving fibres in the other parts + of the body. In respect to the spectra in the eye, this is well + illustrated in No. <a href="#sect_XL_7">7</a> and <a + href="#sect_XL_8">8</a>, of Sect. XL. Epileptic convulsions, as the + emprosthotonos and opisthotonos, with the cramp of the calf of the leg, + locked jaw, and other cataleptic fits, appear to originate from pain, as + some of these patients scream aloud before the convulsion takes place; + which seems at first to be an effort to relieve painful sensation, and + afterwards an effort to prevent it.</p> + + <p>In these cases the violent contractions of the fibres produce so much + pain, as to constitute a perpetual excitement; and that in so great a + degree as to allow but small intervals of relaxation of the contracting + fibres as in convulsions, or no intervals at all as in fixed spasms.</p> + + <p><a name="sect_XII_4_6">6</a>. A quantity of stimulus greater than the + last, or longer continued, produces a paralysis of the organ. In many + cases this paralysis is only a temporary effect, as on looking long on a + small area of bright red silk placed on a sheet of white paper on the + floor in a strong light, the red silk gradually becomes paler, and at + length disappears; which evinces that a part of the retina, by being + violently excited, becomes for a time unaffected by the stimulus of that + colour. Thus cathartic medicines, opiates, poisons, contagious matter, + cease to influence our system after it has been habituated to the use of + them, except by the exhibition of increased quantities of them; our + fibres not only become unaffected by stimuli, by which they have + previously been violently irritated, as by the matter of the small-pox or + measles; but they also become unaffected by sensation, where the violent + exertions, which disabled them, were in consequence of too great quantity + of sensation. And lastly the fibres, which become disobedient to + volition, are probably disabled by their too violent exertions in + consequence of too great a quantity of volition.</p> + + <p>After every exertion of our fibres a temporary paralysis succeeds, + whence the intervals of all muscular contractions, as mentioned in No. 3 + and 4 of this Section; the immediate cause of these more permanent kinds + of paralysis is probably owing in the same manner to the too great + exhaustion of the spirit of animation in the affected part; so that a + stronger stimulus is required, or one of a different kind from that, + which occasioned those too violent contractions, to again excite the + affected organ into activity; and if a stronger stimulus could be + applied, it must again induce paralysis.</p> + + <p>For these powerful stimuli excite pain at the same time, that they + produce irritation; and this pain not only excites fibrous motions by its + stimulus, but it also produces volition; and thus all these stimuli + acting at the same time, and sometimes with the addition of their + associations, produce so great exertion as to expend the whole of the + sensorial power in the affected fibres.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XII_5">V</a>. <i>Of Stimulus less than natural.</i></p> + + <p><a name="sect_XII_5_1">1</a>. A quantity of stimulus less than + natural, producing a decreased exertion of sensorial power, occasions an + accumulation of the general quantity of it. This circumstance is + observable in the hemiplagia, in which the patients are perpetually + moving the muscles, which are unaffected. On this account we awake with + greater vigour after sleep, because during so many hours, the great usual + expenditure of sensorial power in the performance of voluntary actions, + and in the exertions of our organs of sense, in consequence of the + irritations occasioned by external objects had been suspended, and a + consequent accumulation had taken place.</p> + + <p>In like manner the exertion of the sensorial power less than natural + in one part of the system, is liable to produce an increase of the + exertion of it in some other part. Thus by the action of vomiting, in + which the natural exertion of the motions of the stomach are destroyed or + diminished, an increased absorption of the pulmonary and cellular + lymphatics is produced, as is known by the increased absorption of the + fluid deposited in them in dropsical cases. But these partial quiescences + of sensorial power are also sometimes attended with other partial + quiescences, which sympathize with them, as cold and pale extremities + from hunger. These therefore are to be ascribed to the associations of + sympathy explained in Sect. <a href="#sect_XXXV">XXXV</a>. and not to the + general accumulation of sensorial power.</p> + + <p><a name="sect_XII_5_2">2</a>. A quantity of stimulus less than + natural, applied to fibres previously accustomed to perpetual stimulus, + is succeeded by accumulation of sensorial power in the affected organ. + The truth of this proposition is evinced, because a stimulus less than + natural, if it be somewhat greater than that above mentioned, will excite + the organ so circumstanced into violent activity. Thus on a frosty day + with wind, the face of a person exposed to the wind is at first pale and + shrunk; but on turning the face from the wind, it becomes soon of a glow + with warmth and flushing. The glow of the skin in emerging from the + cold-bath is owing to the same cause.</p> + + <p>It does not appear, that an accumulation of sensorial power above the + natural quantity is acquired by those muscles, which are not subject to + perpetual stimulus, as the locomotive muscles: these, after the greatest + fatigue, only acquire by rest their usual aptitude to motion; whereas the + vascular system, as the heart and arteries, after a short quiescence, are + thrown into violent action by their natural quantity of stimulus.</p> + + <p>Nevertheless by this accumulation of sensorial power during the + application of decreased stimulus, and by the exhaustion of it during the + action of increased stimulus, it is wisely provided, that the actions of + the vascular muscles and organs of sense are not much deranged by small + variations of stimulus; as the quantity of sensorial power becomes in + some measure inversely as the quantity of stimulus.</p> + + <p><a name="sect_XII_5_3">3</a>. A quantity of stimulus less than that + mentioned above, and continued for some time, induces pain in the + affected organ, as the pain of cold in the hands, when they are immersed + in snow, is owing to a deficiency of the stimulation of heat. Hunger is a + pain from the deficiency of the stimulation of food. Pain in the back at + the commencement of ague-fits, and the head-achs which attend feeble + people, are pains from defect of stimulus, and are hence relieved by + opium, essential oils, spirit of wine.</p> + + <p>As the pains, which originate from defect of stimulus, only occur in + those parts of the system, which have been previously subjected to + perpetual stimulus; and as an accumulation of sensorial power is produced + in the quiescent organ along with the pain, as in cold or hunger, there + is reason to believe, that the pain is owing to the accumulation of + sensorial power. For, in the locomotive muscles, in the retina of the + eye, and other organs of senses, no pain occurs from the absence of + stimulus, nor any great accumulation of sensorial power beyond their + natural quantity, since these organs have not been used to a perpetual + supply of it. There is indeed a greater accumulation occurs in the organ + of vision after its quiescence, because it is subject to more constant + stimulus.</p> + + <p><a name="sect_XII_5_4">4</a>. A certain quantity of stimulus less than + natural induces the moving organ into feebler and more frequent + contractions, as mentioned in No. <a href="#sect_XII_1_4">I. 4</a>. of + this Section. For each contraction moving through a less space, or with + less force, that is, with less expenditure of the spirit of animation, is + sooner relaxed, and the spirit of animation derived at each interval into + the acting fibres being less, these intervals likewise become shorter. + Hence the tremours of the hands of people accustomed to vinous spirit, + till they take their usual stimulus; hence the quick pulse in fevers + attended with debility, which is greater than in fevers attended with + strength; in the latter the pulse seldom beats above 120 times in a + minute, in the former it frequently exceeds 140.</p> + + <p>It must be observed, that in this and the two following articles the + decreased action of the system is probably more frequently occasioned by + deficiency in the quantity of sensorial power, than in the quantity of + stimulus. Thus those feeble constitutions which have large pupils of + their eyes, and all who labour under nervous fevers, seem to owe their + want of natural quantity of activity in the system to the deficiency of + sensorial power; since, as far as can be seen, they frequently possess + the natural quantity of stimulus.</p> + + <p><a name="sect_XII_5_5">5</a>. A certain quantity of stimulus, less + than that above mentioned, inverts the order of successive fibrous + contractions; as in vomiting the vermicular motions of the stomach and + duodenum are inverted, and their contents ejected, which is probably + owing to the exhaustion of the spirit of animation in the acting muscles + by a previous excessive stimulus, as by the root of ipecacuanha, and the + consequent defect of sensorial power. The same retrograde motions affect + the whole intestinal canal in ileus; and the œsophagus in globus + hystericus. See this further explained in Sect. <a + href="#sect_XXIX_11">XXIX. No. 11</a>. on Retrograde Motions.</p> + + <p>I must observe, also, that something similar happens in the production + of our ideas, or sensual motions, when they are too weakly excited; when + any one is thinking intensely about one thing, and carelessly conversing + about another, he is liable to use the word of a contrary meaning to that + which he designed, as cold weather for hot weather, summer for + winter.</p> + + <p><a name="sect_XII_5_6">6</a>. A certain quantity of stimulus, less + than that above mentioned, is succeeded by paralysis, first of the + voluntary and sensitive motions, and afterwards of those of irritation, + and of association, which constitutes death.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XII_6">VI</a>. <i>Cure of increased Exertion.</i></p> + + <p><a name="sect_XII_6_1">1</a>. The cure, which nature has provided for + the increased exertion of any part of the system, consists in the + consequent expenditure of the sensorial power. But as a greater torpor + follows this exhaustion of sensorial power, as explained in the next + paragraph, and a greater exertion succeeds this torpor, the constitution + frequently sinks under these increasing librations between exertion and + quiescence; till at length complete quiescence, that is, death, closes + the scene.</p> + + <p>For, during the great exertion of the system in the hot fit of fever, + an increase of stimulus is produced from the greater momentum of the + blood, the greater distention of the heart and arteries, and the + increased production of heat, by the violent actions of the system + occasioned by this augmentation of stimulus, the sensorial power becomes + diminished in a few hours much beneath its natural quantity, the vessels + at length cease to obey even these great degrees of stimulus, as shewn in + Sect. <a href="#sect_XL_9_1">XL. 9. 1</a>. and a torpor of the whole or + of a part of the system ensues.</p> + + <p>Now as this second cold fit commences with a greater deficiency of + sensorial power, it is also attended with a greater deficiency of + stimulus than in the preceding cold fit, that is, with less momentum of + blood, less distention of the heart. On this account the second cold fit + becomes more violent and of longer duration than the first; and as a + greater accumulation of sensorial power must be produced before the + system of vessels will again obey the diminished stimulus, it follows, + that the second hot fit of fever will be more violent than the former + one. And that unless some other causes counteract either the violent + exertions in the hot fit, or the great torpor in the cold fit, life will + at length be extinguished by the expenditure of the whole of the + sensorial power. And from hence it appears, that the true means of curing + fevers must be such as decrease the action of the system in the hot fit, + and increase it in the cold fit; that is, such as prevent the too great + diminution of sensorial power in the hot fit, and the too great + accumulation of it in the cold one.</p> + + <p><a name="sect_XII_6_2">2</a>. Where the exertion of the sensorial + powers is much increased, as in the hot fits of fever or inflammation, + the following are the usual means of relieving it. Decrease the + irritations by blood-letting, and other evacuations; by cold water taken + into the stomach, or injected as an enema, or used externally; by cold + air breathed into the lungs, and diffused over the skin; with food of + less stimulus than the patient has been accustomed to.</p> + + <p><a name="sect_XII_6_3">3</a>. As a cold fit, or paroxysm of inactivity + of some parts of the system, generally precedes the hot fit, or paroxysm + of exertion, by which the sensorial power becomes accumulated, this cold + paroxysm should be prevented by stimulant medicines and diet, as wine, + opium, bark, warmth, cheerfulness, anger, surprise.</p> + + <p><a name="sect_XII_6_4">4</a>. Excite into greater action some other + part of the system, by which means the spirit of animation may be in part + expended, and thence the inordinate actions of the diseased part may be + lessened. Hence when a part of the skin acts violently, as of the face in + the eruption of the small-pox, if the feet be cold they should be + covered. Hence the use of a blister applied near a topical inflammation. + Hence opium and warm bath relieve pains both from excess and defect of + stimulus.</p> + + <p><a name="sect_XII_6_5">5</a>. First increase the general stimulation + above its natural quantity, which may in some degree exhaust the spirit + of animation, and then decrease the stimulation beneath its natural + quantity. Hence after sudorific medicines and warm air, the application + of refrigerants may have greater effect, if they could be administered + without danger of producing too great torpor of some part of the system; + as frequently happens to people in health from coming out of a warm room + into the cold air, by which a topical inflammation in consequence of + torpor of the mucous membrane of the nostril is produced, and is termed a + cold in the head.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XII_7">VII</a>. <i>Cure of decreased Exertion.</i></p> + + <p><a name="sect_XII_7_1">1</a>. Where the exertion of the sensorial + powers is much decreased, as in the cold fits of fever, a gradual + accumulation of the spirit of animation takes place; as occurs in all + cases where inactivity or torpor of a part of the system exists; this + accumulation of sensorial power increases, till stimuli less than natural + are sufficient to throw it into action, then the cold fit ceases; and + from the action of the natural stimuli a hot one succeeds with increased + activity of the whole system.</p> + + <p>So in fainting fits, or syncope, there is a temporary deficiency of + sensorial exertion, and a consequent quiescence of a great part of the + system. This quiescence continues, till the sensorial power becomes again + accumulated in the torpid organs; and then the usual diurnal stimuli + excite the revivescent parts again into action; but as this kind of + quiescence continues but a short time compared to the cold paroxysm of an + ague, and less affects the circulatory system, a less superabundancy of + exertion succeeds in the organs previously torpid, and a less excess of + arterial activity. See Sect. <a href="#sect_XXXIV_1_6">XXXIV. 1. + 6</a>.</p> + + <p><a name="sect_XII_7_2">2</a>. In the diseases occasioned by a defect + of sensorial exertion, as in cold fits of ague, hysteric complaint, and + nervous fever, the following means are those commonly used. 1. Increase + the stimulation above its natural quantity for some weeks, till a new + habit of more energetic contraction of the fibres is established. This is + to be done by wine, opium, bark, steel, given at exact periods, and in + appropriate quantities; for if these medicines be given in such quantity, + as to induce the least degree of intoxication, a debility succeeds from + the useless exhaustion of spirit of animation in consequence of too great + exertion of the muscles or organs of sense. To these irritative stimuli + should be added the sensitive ones of cheerful ideas, hope, + affection.</p> + + <p><a name="sect_XII_7_3">3</a>. Change the kinds of stimulus. The habits + acquired by the constitution depend on such nice circumstances, that when + one kind of stimulus ceases to excite the sensorial power into the + quantity of exertion necessary to health, it is often sufficient to + change the stimulus for another apparently similar in quantity and + quality. Thus when wine ceases to stimulate the constitution, opium in + appropriate doses supplies the defect; and the contrary. This is also + observed in the effects of cathartic medicines, when one loses its power, + another, apparently less efficacious, will succeed. Hence a change of + diet, drink, and stimulating medicines, is often advantageous in diseases + of debility.</p> + + <p><a name="sect_XII_7_4">4</a>. Stimulate the organs, whose motions are + associated with the torpid parts of the system. The actions of the minute + vessels of the various parts of the external skin are not only associated + with each other, but are strongly associated with those of some of the + internal membranes, and particularly of the stomach. Hence when the + exertion of the stomach is less than natural, and indigestion and + heartburn succeed, nothing so certainly removes these symptoms as the + stimulus of a blister on the back. The coldness of the extremities, as of + the nose, ears, or fingers, are hence the best indication for the + successful application of blisters.</p> + + <p><a name="sect_XII_7_5">5</a>. Decrease the stimulus for a time. By + lessening the quantity of heat for a minute or two by going into the cold + bath, a great accumulation of sensorial power is produced; for not only + the minute vessels of the whole external skin for a time become inactive, + as appears by their paleness; but the minute vessels of the lungs lose + much of their activity also by concert with those of the skin, as appears + from the difficulty of breathing at first going into cold water. On + emerging from the bath the sensorial power is thrown into great exertion + by the stimulus of the common degree of the warmth of the atmosphere, and + a great production of animal heat is the consequence. The longer a person + continues in the cold bath the greater must be the present inertion of a + great part of the system, and in consequence a greater accumulation of + sensorial power. Whence M. Pomè recommends some melancholy patients to be + kept from two to six hours in spring-water, and in baths still + colder.</p> + + <p><a name="sect_XII_7_6">6</a>. Decrease the stimulus for a time below + the natural, and then increase it above natural. The effect of this + process, improperly used, is seen in giving much food, or applying much + warmth, to those who have been previously exposed to great hunger, or to + great cold. The accumulated sensorial power is thrown into so violent + exertion, that inflammations and mortifications supervene, and death + closes the catastrophe. In many diseases this method is the most + successful; hence the bark in agues produces more certain effect after + the previous exhibition of emetics. In diseases attended with violent + pain, opium has double the effect, if venesection and a cathartic have + been previously used. On this seems to have been founded the successful + practice of Sydenham, who used venesection and a cathartic in chlorosis + before the exhibition of the bark, steel, and opiates.</p> + + <p><a name="sect_XII_7_7">7</a>. Prevent any unnecessary expenditure of + sensorial power. Hence in fevers with debility, a decumbent posture is + preferred, with silence, little light, and such a quantity of heat as may + prevent any chill sensation, or any coldness of the extremities. The + pulse of patients in fevers with debility increases in frequency above + ten pulsations in a minute on their rising out of bed. For the + expenditure of sensorial power to preserve an erect posture of the body + adds to the general deficiency of it, and thus affects the + circulation.</p> + + <p><a name="sect_XII_7_8">8</a>. The longer in time and the greater in + degree the quiescence or inertion of an organ has been, so that it still + retains life or excitability, the less stimulus should at first be + applied to it. The quantity of stimulation is a matter of great nicety to + determine, where the torpor or quiescence of the fibres has been + experienced in a great degree, or for a considerable time, as in cold + fits of the ague, in continued fevers with great debility, or in people + famished at sea, or perishing with cold. In the two last cases, very + minute quantities of food should be first supplied, and very few + additional degrees of heat. In the two former cases, but little stimulus + of wine or medicine, above what they had been lately accustomed to, + should be exhibited, and this at frequent and stated intervals, so that + the effect of one quantity may be observed before the exhibition of + another.</p> + + <p>If these circumstances are not attended to, as the sensorial power + becomes accumulated in the quiescent fibres, an inordinate exertion takes + place by the increase of stimulus acting on the accumulated quantity of + sensorial power, and either the paralysis, or death of the contractile + fibres ensues, from the total expenditure of the sensorial power in the + affected organ, owing to this increase of exertion, like the debility + after intoxication. Or, secondly, the violent exertions above mentioned + produce painful sensation, which becomes a new stimulus, and by thus + producing inflammation, and increasing the activity of the fibres already + too great, sooner exhausts the whole of the sensorial power in the acting + organ, and mortification, that is, the death of the part, supervenes.</p> + + <p>Hence there have been many instances of people, whose limbs have been + long benumbed by exposure to cold, who have lost them by mortification on + their being too hastily brought to the fire; and of others, who were + nearly famished at sea, who have died soon after having taken not more + than an usual meal of food. I have heard of two well-attested instances + of patients in the cold fit of ague, who have died from the exhibition of + gin and vinegar, by the inflammation which ensued. And in many fevers + attended with debility, the unlimited use of wine, and the wanton + application of blisters, I believe, has destroyed numbers by the debility + consequent to too great stimulation, that is, by the exhaustion of the + sensorial power by its inordinate exertion.</p> + + <p>Wherever the least degree of intoxication exists, a proportional + debility is the consequence; but there is a golden rule by which the + necessary and useful quantity of stimulus in fevers with debility may be + ascertained. When wine or beer are exhibited either alone or diluted with + water, if the pulse becomes slower the stimulus is of a proper quantity; + and should be repeated every two or three hours, or when the pulse again + becomes quicker.</p> + + <p>In the chronical debility brought on by drinking spirituous or + fermented liquors, there is another golden rule by which I have + successfully directed the quantity of spirit which they may safely + lessen, for there is no other means by which they can recover their + health. It should be premised, that where the power of digestion in these + patients is totally destroyed, there is not much reason to expect a + return to healthful vigour.</p> + + <p>I have directed several of these patients to omit one fourth part of + the quantity of vinous spirit they have been lately accustomed to, and if + in a fortnight their appetite increases, they are advised to omit another + fourth part; but if they perceive that their digestion becomes impaired + from the want of this quantity of spirituous potation, they are advised + to continue as they are, and rather bear the ills they have, than risk + the encounter of greater. At the same time flesh-meat with or without + spice is recommended, with Peruvian bark and steel in small quantities + between their meals, and half a grain of opium or a grain, with five or + eight grains of rhubarb at night.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XIII">XIII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF VEGETABLE ANIMATION.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XIII_1">I</a>. <a href="#sect_XIII_1_1">1</a>. + <i>Vegetables are irritable; mimosa, dionæa muscipula. Vegetable + secretions.</i> <a href="#sect_XIII_1_2">2</a>. <i>Vegetable buds are + inferior animals, are liable to greater or less irritability.</i> <a + href="#sect_XIII_2">II</a>. <i>Stamens and pistils of plants shew marks + of sensibility.</i> <a href="#sect_XIII_3">III</a>. <i>Vegetables possess + some degree of volition.</i> <a href="#sect_XIII_4">IV</a>. <i>Motions of + plants are associated like those of animals.</i> <a + href="#sect_XIII_5">V</a>. <a href="#sect_XIII_5_1">1</a>. <i>Vegetable + structure like that of animals, their anthers and stigmas are living + creatures. Male-flowers of Vallisneria.</i> <a + href="#sect_XIII_5_2">2</a>. <i>Whether vegetables, possess ideas? They + have organs of sense as of touch and smell, and ideas of external + things?</i></p> + +</blockquote> + + <p><a name="sect_XIII_1">I</a>. <a name="sect_XIII_1_1">1</a>. The fibres + of the vegetable world, as well as those of the animal, are excitable + into a variety of motion by irritations of external objects. This appears + particularly in the mimosa or sensitive plant, whose leaves contract on + the slightest injury; the dionæa muscipula, which was lately brought over + from the marshes of America, presents us with another curious instance of + vegetable irritability; its leaves are armed with spines on their upper + edge, and are spread on the ground around the stem; when an insect creeps + on any of them in its passage to the flower or seed, the leaf shuts up + like a steel rat-trap, and destroys its enemy. See Botanic Garden, Part + II. note on Silene.</p> + + <p>The various secretions of vegetables, as of odour, fruit, gum, resin, + wax, honey, seem brought about in the same manner as in the glands of + animals; the tasteless moisture of the earth is converted by the + hop-plant into a bitter juice; as by the caterpillar in the nut-shell the + sweet kernel is converted into a bitter powder. While the power of + absorption in the roots and barks of vegetables is excited into action by + the fluids applied to their mouths like the lacteals and lymphatics of + animals.</p> + + <p><a name="sect_XIII_1_2">2</a>. The individuals of the vegetable world + may be considered as inferior or less perfect animals; a tree is a + congeries of many living buds, and in this respect resembles the branches + of coralline, which are a congeries of a multitude of animals. Each of + these buds of a tree has its proper leaves or petals for lungs, produces + its viviparous or its oviparous offspring in buds or seeds; has its own + roots, which extending down the stem of the tree are interwoven with the + roots of the other buds, and form the bark, which is the only living part + of the stem, is annually renewed, and is superinduced upon the former + bark, which then dies, and with its stagnated juices gradually hardening + into wood forms the concentric circles, which we see in blocks of + timber.</p> + + <p>The following circumstances evince the individuality of the buds of + trees. First, there are many trees, whose whole internal wood is + perished, and yet the branches are vegete and healthy. Secondly, the + fibres of the barks of trees are chiefly longitudinal, resembling roots, + as is beautifully seen in those prepared barks, that were lately brought + from Otaheita. Thirdly, in horizontal wounds of the bark of trees, the + fibres of the upper lip are always elongated downwards like roots, but + those of the lower lip do not approach to meet them. Fourthly, if you + wrap wet moss round any joint of a vine, or cover it with moist earth, + roots will shoot out from it. Fifthly, by the inoculation or engrafting + of trees many fruits are produced from one stem. Sixthly, a new tree is + produced from a branch plucked from an old one, and set in the ground. + Whence it appears that the buds of deciduous trees are so many annual + plants, that the bark is a contexture of the roots of each individual + bud; and that the internal wood is of no other use but to support them in + the air, and that thus they resemble the animal world in their + individuality.</p> + + <p>The irritability of plants, like that of animals, appears liable to be + increased or decreased by habit; for those trees or shrubs, which are + brought from a colder climate to a warmer, put out their leaves and + blossoms a fortnight sooner than the indigenous ones.</p> + + <p>Professor Kalm, in his Travels in New York, observes that the + apple-trees brought from England blossom a fortnight sooner than the + native ones. In our country the shrubs, that are brought a degree or two + from the north, are observed to flourish better than those, which come + from the south. The Siberian barley and cabbage are said to grow larger + in this climate than the similar more southern vegetables. And our hoards + of roots, as of potatoes and onions, germinate with less heat in spring, + after they have been accustomed to the winter's cold, than in autumn + after the summer's heat.</p> + + <p><a name="sect_XIII_2">II</a>. The stamens and pistils of flowers shew + evident marks of sensibility, not only from many of the stamens and some + pistils approaching towards each other at the season of impregnation, but + from many of them closing their petals and calyxes during the cold parts + of the day. For this cannot be ascribed to irritation, because cold means + a defect of the stimulus of heat; but as the want of accustomed stimuli + produces pain, as in coldness, hunger, and thirst of animals, these + motions of vegetables in closing up their flowers must be ascribed to the + disgreeable sensation, and not to the irritation of cold. Others close up + their leaves during darkness, which, like the former, cannot be owing to + irritation, as the irritating material is withdrawn.</p> + + <p>The approach of the anthers in many flowers to the stigmas, and of the + pistils of some flowers to the anthers, must be ascribed to the passion + of love, and hence belongs to sensation, not to irritation.</p> + + <p><a name="sect_XIII_3">III</a>. That the vegetable world possesses some + degree of voluntary powers, appears from their necessity to sleep, which + we have shewn in Sect. <a href="#sect_XVIII">XVIII</a>. to consist in the + temporary abolition of voluntary power. This voluntary power seems to be + exerted in the circular movement of the tendrils of vines, and other + climbing vegetables; or in the efforts to turn the upper surface of their + leaves, or their flowers to the light.</p> + + <p><a name="sect_XIII_4">IV</a>. The associations of fibrous motions are + observable in the vegetable world, as well as in the animal. The + divisions of the leaves of the sensitive plant have been accustomed to + contract at the same time from the absence of light; hence if by any + other circumstance, as a slight stroke or injury, one division is + irritated into contraction, the neighbouring ones contract also, from + their motions being associated with those of the irritated part. So the + various stamina of the class of syngenesia have been accustomed to + contract together in the evening, and thence if you stimulate one of them + with a pin, according to the experiment of M. Colvolo, they all contract + from their acquired associations.</p> + + <p>To evince that the collapsing of the sensitive plant is not owing to + any mechanical vibrations propagated along the whole branch, when a + single leaf is struck with the finger, a leaf of it was slit with sharp + scissors, and some seconds of time passed before the plant seemed + sensible of the injury; and then the whole branch collapsed as far as the + principal stem: this experiment was repeated several times with the least + possible impulse to the plant.</p> + + <p><a name="sect_XIII_5">V</a>. <a name="sect_XIII_5_1">1</a>. For the + numerous circumstances in which vegetable buds are analogous to animals, + the reader is referred to the additional notes at the end of the Botanic + Garden, Part I. It is there shewn, that the roots of vegetables resemble + the lacteal system of animals; the sap-vessels in the early spring, + before their leaves expand, are analogous to the placental vessels of the + fœtus; that the leaves of land-plants resemble lungs, and those of + aquatic plants the gills of fish; that there are other systems of vessels + resembling the vena portarum of quadrupeds, or the aorta of fish; that + the digestive power of vegetables is similar to that of animals + converting the fluids, which they absorb, into sugar; that their seeds + resemble the eggs of animals, and their buds and bulbs their viviparous + offspring. And, lastly, that the anthers and stigmas are real animals, + attached indeed to their parent tree like polypi or coral insects, but + capable of spontaneous motion; that they are affected with the passion of + love, and furnished with powers of reproducing their species, and are fed + with honey like the moths and butterflies, which plunder their nectaries. + See Botanic Garden, Part I. add. note XXXIX.</p> + + <p>The male flowers of vallisneria approach still nearer to apparent + animality, as they detach themselves from the parent plant, and float on + the surface of the water to the female ones. Botanic Garden, Part II. + Art. Vallisneria. Other flowers of the classes of monecia and diecia, and + polygamia, discharge the fecundating farina, which floating in the air is + carried to the stigma of the female flowers, and that at considerable + distances. Can this be effected by any specific attraction? or, like the + diffusion of the odorous particles of flowers, is it left to the currents + of winds, and the accidental miscarriages of it counteracted by the + quantity of its production?</p> + + <p><a name="sect_XIII_5_2">2</a>. This leads us to a curious enquiry, + whether vegetables have ideas of external things? As all our ideas are + originally received by our senses, the question may be changed to, + whether vegetables possess any organs of sense? Certain it is, that they + possess a sense of heat and cold, another of moisture and dryness, and + another of light and darkness; for they close their petals occasionally + from the presence of cold, moisture, or darkness. And it has been already + shewn, that these actions cannot be performed simply from irritation, + because cold and darkness are negative quantities, and on that account + sensation or volition are implied, and in consequence a sensorium or + union of their nerves. So when we go into the light, we contract the + iris; not from any stimulus of the light on the fine muscles of the iris, + but from its motions being associated with the sensation of too much + light on the retina: which could not take place without a sensorium or + center of union of the nerves of the iris with those of vision. See + Botanic Garden, Part I. Canto 3. l. 440. note.</p> + + <p>Besides these organs of sense, which distinguish cold, moisture, and + darkness, the leaves of mimosa, and of dionæa, and of drosera, and the + stamens of many flowers, as of the berbery, and the numerous class of + syngenesia, are sensible to mechanic impact, that is, they possess a + sense of touch, as well as a common sensorium; by the medium of which + their muscles are excited into action. Lastly, in many flowers the + anthers, when mature, approach the stigma, in others the female organ + approaches to the male. In a plant of collinsonia, a branch of which is + now before me, the two yellow stamens are about three eights of an inch + high, and diverge from each other, at an angle of about fifteen degrees, + the purple style is half an inch high, and in some flowers is now applied + to the stamen on the right hand, and in others to that of the left; and + will, I suppose, change place to-morrow in those, where the anthers have + not yet effused their powder.</p> + + <p>I ask, by what means are the anthers in many flowers, and stigmas in + other flowers, directed to find their paramours? How do either of them + know, that the other exists in their vicinity? Is this curious kind of + storge produced by mechanic attraction, or by the sensation of love? The + latter opinion is supported by the strongest analogy, because a + reproduction of the species is the consequence; and then another organ of + sense must be wanted to direct these vegetable amourettes to find each + other, one probably analogous to our sense of smell, which in the animal + world directs the new-born infant to its source of nourishment, and they + may thus possess a faculty of perceiving as well as of producing + odours.</p> + + <p>Thus, besides a kind of taste at the extremities of their roots, + similar to that of the extremities of our lacteal vessels, for the + purpose of selecting their proper food: and besides different kinds of + irritability residing in the various glands, which separate honey, wax, + resin, and other juices from their blood; vegetable life seems to possess + an organ of sense to distinguish the variations of heat, another to + distinguish the varying degrees of moisture, another of light, another of + touch, and probably another analogous to our sense of smell. To these + must be added the indubitable evidence of their passion of love, and I + think we may truly conclude, that they are furnished with a common + sensorium belonging to each bud and that they must occasionally repeat + those perceptions either in their dreams or waking hours, and + consequently possess ideas of so many of the properties of the external + world, and of their own existence.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XIV">XIV</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE PRODUCTION OF IDEAS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XIV_1">I</a>. <i>Of material and immaterial beings. + Doctrine of St. Paul.</i> <a href="#sect_XIV_2">II</a>. <a + href="#sect_XIV_2_1">1</a>. <i>Of the sense of touch. Of solidity.</i> <a + href="#sect_XIV_2_2">2</a>. <i>Of figure. Motion. Time. Place. Space. + Number.</i> <a href="#sect_XIV_2_3">3</a>. <i>Of the penetrability of + matter.</i> <a href="#sect_XIV_2_4">4</a>. <i>Spirit of animation + possesses solidity, figure, visibility, &c. Of Spirits and + angels.</i> <a href="#sect_XIV_2_5">5</a>. <i>The existence of external + things.</i> <a href="#sect_XIV_3">III</a>. <i>Of vision.</i> <a + href="#sect_XIV_4">IV</a>. <i>Of hearing.</i> <a + href="#sect_XIV_5">V</a>. <i>Of smell and taste.</i> <a + href="#sect_XIV_6">VI</a>. <i>Of the organ of sense by which we perceive + heat and cold, not by the sense of touch.</i> <a + href="#sect_XIV_7">VII</a>. <i>Of the sense of extension, the whole of + the locomotive muscles may be considered as one organ of sense.</i> <a + href="#sect_XIV_8">VIII</a>. <i>Of the senses of hunger, thirst, want of + fresh air, suckling children, and lust.</i> <a href="#sect_XIV_9">IX</a>. + <i>Of many other organs of sense belonging to the glands. Of painful + sensations from the excess of light, pressure, heat, itching, caustics, + and electricity.</i></p> + +</blockquote> + + <p><a name="sect_XIV_1">I</a>. Philosophers have been much perplexed to + understand, in what manner we become acquainted with the external world; + insomuch that Dr. Berkly even doubted its existence, from having observed + (as he thought) that none of our ideas resemble their correspondent + objects. Mr. Hume asserts, that our belief depends on the greater + distinctness or energy of our ideas from perception; and Mr. Reid has + lately contended, that our belief of external objects is an innate + principle necessarily joined with our perceptions.</p> + + <p>So true is the observation of the famous Malbranch, "that our senses + are not given us to discover the essences of things, but to acquaint us + with the means of preserving our existence," (L. I. ch. v.) a melancholy + reflection to philosophers!</p> + + <p>Some philosophers 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 + itself; the other is the cause of all motion, and is either termed the + power of gravity, or of specific attraction, or the spirit of animation. + This immaterial agent is supposed to exist in or with matter, but to be + quite distinct from it, and to be equally capable of existence, after the + matter, which now possesses it, is decomposed.</p> + + <p>Nor is this theory ill supported by analogy, since heat, electricity, + and magnetism, can be given to or taken from a piece of iron; and must + therefore exist, whether separated from the metal, or combined with it. + From a parity of reasoning, the spirit of animation, would appear to be + capable of existing as well separately from the body as with it.</p> + + <p>I beg to be understood, that I do not wish to dispute about words, and + am ready to allow, that the powers of gravity, specific attraction, + electricity, magnetism, and even the spirit of animation, may consist of + matter of a finer kind; and to believe, with St. Paul and Malbranch, that + the ultimate cause only of all motion is immaterial, that is God. St. + Paul says, "in him we live and move, and have our being;" and, in the + 15th chapter to the Corinthians, distinguishes between the psyche or + living spirit, and the pneuma or reviving spirit. By the words spirit of + animation or sensorial power, I mean only that animal life, which mankind + possesses in common with brutes, and in some degree even with vegetables, + and leave the consideration of the immortal part of us, which is the + object of religion, to those who treat of revelation.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_2">II</a>. <a name="sect_XIV_2_1">1</a>. <i>Of the Sense of Touch.</i></p> + + <p>The first idea we become acquainted with, are those of the sense of + touch; for the fœtus must experience some varieties of agitation, + and exert some muscular action, in the womb; and may with great + probability be supposed thus to gain some ideas of its own figure, of + that of the uterus, and of the tenacity of the fluid, that surrounds it, + (as appears from the facts mentioned in the succeeding Section upon + Instinct.)</p> + + <p>Many of the organs of sense are confined to a small part of the body, + as the nostrils, ear, or eye, whilst the sense of touch is diffused over + the whole skin, but exists with a more exquisite degree of delicacy at + the extremities of the fingers and thumbs, and in the lips. The sense of + touch is thus very commodiously disposed for the purpose of encompassing + smaller bodies, and for adapting itself to the inequalities of larger + ones. The figure of small bodies seems to be learnt by children by their + lips as much as by their fingers; on which account they put every new + object to their mouths, when they are satiated with food, as well as when + they are hungry. And puppies seem to learn their ideas of figure + principally by the lips in their mode of play.</p> + + <p>We acquire our tangible ideas of objects either by the simple pressure + of this organ of touch against a solid body, or by moving our organ of + touch along the surface of it. In the former case we learn the length and + breadth of the object by the quantity of our organ of touch, that is + impressed by it: in the latter case we learn the length and breadth of + objects by the continuance of their pressure on our moving organ of + touch.</p> + + <p>It is hence, that we are very slow in acquiring our tangible ideas, + and very slow 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 solidity of + every part of that figure, I must conceive myself as passing my fingers + over it, and seem in some measure to feel the idea, as I formerly did the + impression, at the ends of them, and am thus very slow in distinctly + recollecting it.</p> + + <p>When a body compresses any part of our sense of touch, what happens? + First, this part of our sensorium undergoes a mechanical compression, + which is termed a stimulus; secondly, an idea, or contraction of a part + of the organ of sense is excited; thirdly, a motion of the central parts, + or of the whole sensorium, which is termed sensation, is produced; and + these three constitute the perception of solidity.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_2_2">2</a>. <i>Of Figure, Motion, Time, Place, Space, Number.</i></p> + + <p>No one will deny, that the medulla of the brain and nerves has a + certain figure; which, as it is diffused through nearly the whole of the + body, must have nearly the figure of that body. Now it follows, that the + spirit 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 spirit of animation + has also the same figure as the medulla above described. I appeal to + common sense! the spirit 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 exsection from the + body.—Does it act any where else?—No; then it certainly + exists in this part of space, and no where else; that is, it hath figure; + namely, the figure of the nervous system, which is nearly the figure of + the body. When the idea of solidity is excited, as above explained, a + part of the extensive organ of touch is compressed by some external body, + and this part of the sensorium so compressed exactly resembles <i>in + figure</i> the figure of the body that compressed it. Hence, when we + acquire the idea of solidity, we acquire at the same time the idea of + <font class="sc">FIGURE</font>; and this idea of figure, or motion of + <i>a part</i> of the organ of touch, exactly resembles <i>in its + figure</i> the figure of the body that occasions it; and thus exactly + acquaints us with this property of the external world.</p> + + <p>Now, as the whole universe with all its parts possesses a certain form + or figure, if any part of it moves, that form or figure of the whole is + varied: hence, as <font class="sc">MOTION</font> is no other than a + perpetual variation of figure, our idea of motion is also a real + resemblance of the motion that produced it.</p> + + <p>It may be said 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 particle <i>x</i> on one + side of this globe is not the <i>same</i> figure as the figure of + <i>y</i> on the other side, any more than the particles themselves are + the same, though they are <i>similar</i> figures; and hence they cannot + change place with each other without disturbing or changing the figure of + the whole.</p> + + <p>Our idea of <font class="sc">TIME</font> is from the same source, but + is more abstracted, as it includes only the comparative velocities of + these variations of figure; hence if it be asked, How long was this book + in printing? it may be answered, Whilst the sun was passing through + Aries.</p> + + <p>Our idea of <font class="sc">PLACE</font> includes only the figure of + a group of bodies, not the figures of the bodies themselves. If it be + asked where is Nottinghamshire, the answer is, it is surrounded by + Derbyshire, Lincolnshire and Leicestershire; hence place is our idea of + the figure of one body surrounded by the figures of other bodies.</p> + + <p>The idea of <font class="sc">SPACE</font> is a more abstracted idea of + place excluding the group of bodies.</p> + + <p>The idea of <font class="sc">NUMBER</font> includes only the + particular arrangements, or distributions of a group of bodies, and is + therefore only a more abstracted idea of the parts of the figure of the + group of bodies; thus when I say England is divided into forty counties, + I only speak of certain divisions of its figure.</p> + + <p>Hence arises the certainty of the mathematical sciences, as they + explain these properties of bodies, which are exactly resembled by our + ideas of them, whilst we are obliged to collect almost all our other + knowledge from experiment; that is, by observing the effects exerted by + one body upon another.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_2_3">3</a>. <i>Of the Penetrability of Matter.</i></p> + + <p>The impossibility of two bodies existing together in the same space + cannot be deduced from our idea of solidity, or of figure. As soon as we + perceive the motions of objects that surround us, and learn that we + possess a power to move our own bodies, we experience, that those + objects, which excite in us the idea of solidity and of figure, oppose + this voluntary movement of our own organs; as whilst I endeavour to + compress between my hands an ivory ball into a spheroid. And we are hence + taught by experience, that our own body and those, which we touch, cannot + exist in the same part of space.</p> + + <p>But this by no means demonstrates, that no two bodies can exist + together in the same part of space. Galilæo in the preface to his works + seems to be of opinion, that matter is not impenetrable; Mr. Michel, and + Mr. Boscowich in his Theoria. Philos. Natur. have espoused this + hypothesis: which has been lately published by Dr. Priestley, to whom the + world is much indebted for so many important discoveries in science. + (Hist. of Light and Colours, p. 391.) The uninterrupted passage of light + through transparent bodies, of the electric æther through metallic and + aqueous bodies, and of the magnetic effluvia through all bodies, would + seem to give some probability to this opinion. Hence it appears, that + beings may exist without possessing the property of solidity, as well as + they can exist without possessing the properties, which excite our smell + or taste, and can thence occupy space without detruding other bodies from + it; but we cannot become acquainted with such beings by our sense of + touch, any more than we can with odours or flavours without our senses of + smell and taste.</p> + + <p>But that any being can exist without existing in space, is to my ideas + utterly incomprehensible. My appeal is to common sense. <i>To be</i> + implies a when and a where; the one is comparing it with the motions of + other beings, and the other with their situations.</p> + + <p>If there was but one object, as the whole creation may be considered + as one object, then I cannot ask where it exists? for there are no other + objects to compare its situation with. Hence if any one denies, that a + being exists in space, he denies, that there are any other beings but + that one; for to answer the question, "Where does it exist?" is only to + mention the situation of the objects that surround it.</p> + + <p>In the same manner if it be asked—"When does a being exist?" The + answer only specifies the successive motions either of itself, or of + other bodies; hence to say, a body exists not in time, is to say, that + there is, or was, no motion in the world.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_2_4">4</a>. <i>Of the Spirit of Animation.</i></p> + + <p>But though there may exist beings in the universe, that have not the + property of solidity; that is, which can possess any part of space, at + the same time that it is occupied by other bodies; yet there may be other + beings, that can assume this property of solidity, or disrobe themselves + of it occasionally, as we are taught of spirits, and of angels; and it + would seem, that <font class="sc">THE SPIRIT OF ANIMATION</font> must be + endued with this property, otherwise how could it occasionally give + motion to the limbs of animals?—or be itself stimulated into motion + by the obtrusions of surrounding bodies, as of light, or odour?</p> + + <p>If the spirit of animation was always necessarily penetrable, it could + not influence or be influenced by the solidity of common matter; they + would exist together, but could not detrude each other from the part of + space, where they exist; that is, they could not communicate motion to + each other. <i>No two things can influence or affect each other, which + have not some property common to both of them</i>; for to influence or + affect another body is to give or communicate some property to it, that + it had not before; but how can one body give that to another, which it + does not possess itself?—The words imply, that they must agree in + having the power or faculty of possessing some common property. Thus if + one body removes another from the part of space, that it possesses, it + must have the power of occupying that space itself: and if one body + communicates heat or motion to another, it follows, that they have alike + the property of possessing heat or motion.</p> + + <p>Hence the spirit of animation at the time it communicates or receives + motion from solid bodies, must itself possess some property of solidity. + And in consequence at the time it receives other kinds of motion from + light, it must possess that property, which light possesses, to + communicate that kind of motion; and for which no language has a name, + unless it may be termed Visibility. And at the time it is stimulated into + other kinds of animal motion by the particles of sapid and odorous bodies + affecting the senses of taste and smell, it must resemble these particles + of flavour, and of odour, in possessing some similar or correspondent + property; and for which language has no name, unless we may use the words + Saporosity and Odorosity for those common properties, which are possessed + by our organs of taste and smell, and by the particles of sapid and + odorous bodies; as the words Tangibility and Audibility may express the + common property possessed by our organs of touch, and of hearing, and by + the solid bodies, or their vibrations, which affect those organs.</p> + + <p><a name="sect_XIV_2_5">5</a>. Finally, though the figures of bodies + are in truth resembled by the figure of the part of the organ of touch, + which is stimulated into motion; and that organ resembles the solid body, + which stimulates it, in its property of solidity; and though the sense of + hearing resembles the vibrations of external bodies in its capability of + being stimulated into motion by those vibrations; and though our other + organs of sense resemble the bodies, that stimulate them, in their + capability of being stimulated by them; and we hence become acquainted + with these properties of the external world; yet as we can repeat all + these motions of our organs of sense by the efforts of volition, or in + consequence of the sensation of pleasure or pain, or by their association + with other fibrous motions, as happens in our reveries or in sleep, there + would still appear to be some difficulty in demonstrating the existence + of any thing external to us.</p> + + <p>In our dreams we cannot determine this circumstance, because our power + of volition is suspended, and the stimuli of external objects are + excluded; but in our waking hours we can compare our ideas belonging to + one sense with those belonging to another, and can thus distinguish the + ideas occasioned by irritation from those excited by sensation, volition, + or association. Thus if the idea of the sweetness of sugar should be + excited in our dreams, the whiteness and hardness of it occur at the same + time by association; and we believe a material lump of sugar present + before us. But if, in our waking hours, the idea of the sweetness of + sugar occurs to us, the stimuli of surrounding objects, as the edge of + the table, on which we press, or green colour of the grass, on which we + tread, prevent the other ideas of the hardness and whiteness of the sugar + from being exerted by association. Or if they should occur, we + voluntarily compare them with the irritative ideas of the table or grass + above mentioned, and detect their fallacy. We can thus distinguish the + ideas caused by the stimuli of external objects from those, which are + introduced by association, sensation, or volition; and during our waking + hours can thus acquire a knowledge of the external world. Which + nevertheless we cannot do in our dreams, because we have neither + perceptions of external bodies, nor the power of volition to enable us to + compare them with the ideas of imagination.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_3">III</a>. <i>Of Vision.</i></p> + + <p>Our eyes observe a difference of colour, or of shade, in the + prominences and depressions of objects, and that those shades uniformly + vary, when the sense of touch observes any variation. Hence when the + retina becomes stimulated by colours or shades of light in a certain + form, as in a circular spot; we know by experience, that this is a sign, + that a tangible body is before us; and that its figure is resembled by + the miniature figure of the part of the organ of vision, that is thus + stimulated.</p> + + <p>Here whilst the stimulated part of the retina resembles exactly the + visible figure of the whole in miniature, the various kinds of stimuli + from different colours mark the visible figures of the minuter parts; and + by habit we instantly recall the tangible figures.</p> + + <p>Thus when a tree is the object of sight, a part of the retina + resembling a flat branching figure is stimulated by various shades of + colours; but it is by suggestion, that the gibbosity of the tree, and the + moss, that fringes its trunk, appear before us. These are ideas of + suggestion, which we feel or attend to, associated with the motions of + the retina, or irritative ideas, which we do not attend to.</p> + + <p>So that though our visible ideas resemble in miniature the outline of + the figure of coloured bodies, in other respects they serve only as a + language, which by acquired associations introduce the tangible ideas of + bodies. Hence it is, that this sense is so readily deceived by the art of + the painter to our amusement and instruction. The reader will find much + very curious knowledge on this subject in Bishop Berkley's Essay on + Vision, a work of great ingenuity.</p> + + <p>The immediate object however of the sense of vision is light; this + fluid, though its velocity is so great, appears to have no perceptible + mechanical impulse, as was mentioned in the third Section, but seems to + stimulate the retina into animal motion by its transmission through this + part of the sensorium: for though the eyes of cats or other animals + appear luminous in obscure places; yet it is probable, that none of the + light, which falls on the retina, is reflected from it, but adheres to or + enters into combination with the choroide coat behind it.</p> + + <p>The combination of the particles of light with opake 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 sunbeams + communicate no heat in their passage through transparent bodies, with + which they do not combine, as the air continues cool even in the focus of + the largest burning-glasses, which in a moment vitrifies a particle of + opaque matter.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_4">IV</a>. <i>Of the Organ of Hearing.</i></p> + + <p>It is generally believed, that the tympanum of the ear vibrates + mechanically, when exposed to audible sounds, like the strings of one + musical instrument, when the same notes are struck upon another. Nor is + this opinion improbable, as the muscles and cartilages of the larynx are + employed in producing variety of tones by mechanical vibration: so the + muscles and bones of the ear seem adapted to increase or diminish the + tension of the tympanum for the purposes of similar mechanical + vibrations.</p> + + <p>But it appears from dissection, that the tympanum is not the immediate + organ of hearing, but that like the humours and cornea of the eye, it is + only of use to prepare the object for the immediate organ. For the portio + mollis of the auditory nerve is not spread upon the tympanum, but upon + the vestibulum, and cochlea, and semicircular canals of the ear; while + between the tympanum and the expansion of the auditory nerve the cavity + is said by Dr. Cotunnus and Dr. Meckel to be filled with water; as they + had frequently observed by freezing the heads of dead animals before they + dissected them; and water being a more dense 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 absolutely necessary for the + perception of sound: for some people, who from these defects would have + been completely deaf, have distinguished acute or grave sounds by the + tremours of a stick held between their teeth propagated along the bones + of the head, (Haller. Phys. T. V. p. 295).</p> + + <p>Hence it appears, that the immediate organ of hearing is not affected + by the particles of the air themselves, but is stimulated into animal + motion by the vibrations of them. And it is probable from the loose + bones, which are found in the heads of some fishes, that the vibrations + of water are sensible to the inhabitants of that element by a similar + organ.</p> + + <p>The motions of the atmosphere, which we become acquainted with by the + sense of touch, are combined with its solidity, weight, or vis intertiæ; + whereas those, that are perceived by this organ, depend alone on its + elasticity. But though the vibration of the air is the immediate object + of the sense of hearing, yet the ideas, we receive by this sense, like + those received from light, are only as a language, which by acquired + associations acquaints us with those motions of tangible bodies, which + depend on their elasticity; and which we had before learned by our sense + of touch.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_5">V</a>. <i>Of Smell and of Taste.</i></p> + + <p>The objects of smell are dissolved in the fluid atmosphere, and those + of taste in the saliva, or other aqueous fluid, for the better diffusing + them on their respective organs, which seem to be stimulated into animal + motion perhaps by the chemical affinities of these particles, which + constitute the sapidity and odorosity of bodies with the nerves of sense, + which perceive them.</p> + + <p>Mr. Volta has lately observed a curious circumstance relative to our + sense of taste. If a bit of clean lead and a bit of clean silver be + separately applied to the tongue and palate no taste is perceived; but by + applying them in contact in respect to the parts out of the mouth, and + nearly so in respect to the parts, which are immediately applied to the + tongue and palate, a saline or acidulous taste is perceived, as of a + fluid like a stream of electricity passing from one of them to the other. + This new application of the sense of taste deserves further + investigation, as it may acquaint us with new properties of matter.</p> + + <p>From the experiments above mentioned of Galvani, Volta, Fowler, and + others, it appears, that a plate of zinc and a plate of silver have + greater effect than lead and silver. If one edge of a plate of silver + about the size of half a crown-piece be placed upon the tongue, and one + edge of a plate of zinc about the same size beneath the tongue, and if + their opposite edges are then brought into contact before the point of + the tongue, a taste is perceived at the moment of their coming into + contact; secondly, if one of the above plates be put between the upper + lip and the gum of the fore-teeth, and the other be placed under the + tongue, and their exterior edges be then brought into contact in a + darkish room, a flash of light is perceived in the eyes.</p> + + <p>These effects I imagine only shew the sensibility of our nerves of + sense to very small quantities of the electric fluid, as it passes + through them; for I suppose these sensations are occasioned by slight + electric shocks produced in the following manner. By the experiments + published by Mr. Bennet, with his ingenious doubler of electricity, which + is the greatest discovery made in that science since the coated jar, and + the eduction of lightning from the skies, it appears that zinc was always + found minus, and silver was always found plus, when both of them were in + their separate state. Hence, when they are placed in the manner above + described, as soon as their exterior edges come nearly into contact, so + near as to have an extremely thin plate of air between them, that plate + of air becomes charged in the same manner as a plate of coated glass; and + is at the same instant discharged through the nerves of taste or of + sight, and gives the sensations, as above described, of light or of + saporocity; and only shews the great sensibility of these organs of sense + to the stimulus of the electric fluid in suddenly passing through + them.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_6">VI</a>. <i>Of the Sense of Heat.</i></p> + + <p>There are many experiments in chemical writers, that evince the + existence of heat as a fluid element, which covers and pervades all + bodies, and is attracted by the solutions of some of them, and is + detruded from the combination of others. Thus from the combinations of + metals with acids, and from those combinations of animal fluids, which + are termed secretions, this fluid matter of heat is given out amongst the + neighbouring bodies; and in the solutions of salts in water, or of water + in air, it is absorbed from the bodies, that surround them; whilst in its + facility in passing through metallic bodies, and its difficulty in + pervading resins and glass, it resembles the properties of the electric + aura; and is like that excited by friction, and seems like that to + gravitate amongst other bodies in its uncombined state, and to find its + equilibrium.</p> + + <p>There is no circumstance of more consequence in the animal economy + than a due proportion of this fluid of heat; for the digestion of our + nutriment in the stomach and bowels, and the proper qualities of all our + secreted fluids, as they are produced or prepared partly by animal and + partly by chemical processes, depend much on the quantity of heat; the + excess of which, or its deficiency, alike gives us pain, and induces us + to avoid the circumstances that occasion them. And in this the perception + of heat essentially differs from the perceptions of the sense of touch, + as we receive pain from too great pressure of solid bodies, but none from + the absence of it. It is hence probable, that nature has provided us with + a set of nerves for the perception of this fluid, which anatomists have + not yet attended to.</p> + + <p>There may be some difficulty in the proof of this assertion; if we + look at a hot fire, we experience no pain of the optic nerve, though the + heat along with the light must be concentrated upon it. Nor does warm + water or warm oil poured into the ear give pain to the organ of hearing; + and hence as these organs of sense do not perceive small excesses or + deficiences of heat; and as heat has no greater analogy to the solidity + or to the figures of bodies, than it has to their colours or vibrations; + there seems no sufficient reason for our ascribing the perception of heat + and cold to the sense of touch; to which it has generally been + attributed, either because it is diffused beneath the whole skin like the + sense of touch, or owing to the inaccuracy of our observations, or the + defect of our languages.</p> + + <p>There is another circumstance would induce us to believe, that the + perceptions of heat and cold do not belong to the organ of touch; since + the teeth, which are the least adapted for the perceptions of solidity or + figure, are the most sensible to heat or cold; whence we are forewarned + from swallowing those materials, whose degree of coldness or of heat + would injure our stomachs.</p> + + <p>The following is an extract from a letter of Dr. R.W. Darwin, of + Shrewsbury, when he was a student at Edinburgh. "I made an experiment + yesterday in our hospital, which much favours your opinion, that the + sensation of heat and of touch depend on different sets of nerves. A man + who had lately recovered from a fever, and was still weak, was seized + with violent cramps in his legs and feet; which were removed by opiates, + except that one of his feet remained insensible. Mr. Ewart pricked him + with a pin in five or six places, and the patient declared he did not + feel it in the least, nor was he sensible of a very smart pinch. I then + held a red-hot poker at some distance, and brought it gradually nearer + till it came within three inches, when he asserted that he felt it quite + distinctly. I suppose some violent irritation on the nerves of touch had + caused the cramps, and had left them paralytic; while the nerves of heat, + having suffered no increased stimulus, retained their irritability."</p> + + <p>Add to this, that the lungs, though easily stimulated into + inflammation, are not sensible to heat. See Class. III. 1. 1. 10.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_7">VII</a>. <i>Of the Sense of Extension.</i></p> + + <p>The organ of touch is properly the sense of pressure, but the muscular + fibres themselves constitute the organ of sense, that feels extension. + The sense of pressure is always attended with the ideas of the figure and + solidity of the object, neither of which accompany our perception of + extension. The whole set of muscles, whether they are hollow ones, as the + heart, arteries, and intestines, or longitudinal ones attached to bones, + contract themselves, whenever they are stimulated by forcible elongation; + and it is observable, that the white muscles, which constitute the + arterial system, seem to be excited into contraction from no other kinds + of stimulus, according to the experiments of Haller. And hence the + violent pain in some inflammations, as in the paronychia, obtains + immediate relief by cutting the membrane, that was stretched by the + tumour of the subjacent parts.</p> + + <p>Hence the whole muscular system may be considered as one organ of + sense, and the various attitudes of the body, as ideas belonging to this + organ, of many of which we are hourly conscious, while many others, like + the irritative ideas of the other senses, are performed without our + attention.</p> + + <p>When the muscles of the heart cease to act, the refluent blood again + distends or elongates them; and thus irritated they contract as before. + The same happens to the arterial system, and I suppose to the + capillaries, intestines, and various glands of the body.</p> + + <p>When the quantity of urine, or of excrement, distends the bladder, or + rectum, those parts contract, and exclude their contents, and many other + muscles by association act along with them; but if these evacuations are + not soon complied with, pain is produced by a little further extension of + the muscular fibres: a similar pain is caused in the muscles, when a limb + is much extended for the reduction of dislocated bones; and in the + punishment of the rack: and in the painful cramps of the calf of the leg, + or of other muscles, for a greater degree of contraction of a muscle, + than the movement of the two bones, to which its ends are affixed, will + admit of, must give similar pain to that, which is produced by extending + it beyond its due length. And the pain from punctures or incisions arises + from the distention of the fibres, as the knife passes through them; for + it nearly ceases as soon as the division is completed.</p> + + <p>All these motions of the muscles, that are thus naturally excited by + the stimulus of distending bodies, are also liable to be called into + strong action by their catenation, with the irritations or sensations + produced by the momentum of the progressive particles of blood in the + arteries, as in inflammatory fevers, or by acrid substances on other + sensible organs, as in the strangury, or tenesmus, or cholera.</p> + + <p>We shall conclude this account of the sense of extension by observing, + that the want of its object is attended with a disagreeable sensation, as + well as the excess of it. In those hollow muscles, which have been + accustomed to it, this disagreeable sensation is called faintness, + emptiness, and sinking; and, when it arises to a certain degree, is + attended with syncope, or a total quiescence of all motions, but the + internal irritative ones, as happens from sudden loss of blood, or in the + operation of tapping in the dropsy.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XIV_8">VIII</a>. <i>Of the Appetites of Hunger, Thirst, Heat, Extension, the want +of fresh Air, animal Love, and the Suckling of Children.</i></p> + + <p>Hunger is most probably perceived by those numerous ramifications of + nerves that are seen about the upper opening of the stomach; and thirst + by the nerves about the fauces, and the top of the gula. The ideas of + these senses are few in the generality of mankind, but are more numerous + in those, who by disease, or indulgence, desire particular kinds of foods + or liquids.</p> + + <p>A sense of heat has already been spoken of, which may with propriety + be called an appetite, as we painfully desire it, when it is deficient in + quantity.</p> + + <p>The sense of extension may be ranked amongst these appetites, since + the deficiency of its object gives disagreeable sensation; when this + happens in the arterial system, it is called faintness, and seems to bear + some analogy to hunger and to cold; which like it are attended with + emptiness of a part of the vascular system.</p> + + <p>The sense of want of fresh air has not been attended to, but is as + distinct as the others, and the first perhaps that we experience after + our nativity; from the want of the object of this sense many diseases 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 pleasure or pain from + the suckling their offspring. The want of which either owing to the death + of their progeny, or to the fashion of their country, has been fatal to + many of the sex. The males have also pectoral glands, which are + frequently turgid with a thin milk at their nativity, and are furnished + with nipples, which erect on titillation like those of the female; but + which seem now to be of no further use, owing perhaps to some change + which these animals have undergone in the gradual progression of the + formation of the earth, and of all that it inhabit.</p> + + <p>These seven last mentioned senses may properly be termed appetites, as + they differ from those of touch, sight, hearing, taste, and smell, in + this respect; that they are affected with pain as well by the defect of + their objects as by the excess of them, which is not so in the latter. + Thus cold and hunger give us pain, as well as an excess of heat or + satiety; but it is not so with darkness and silence.</p> + + <p><a name="sect_XIV_9">IX</a>. Before we conclude this Section on the + organs of sense, we must observe, that, as far as we know, there are many + more senses, than have been here mentioned, as every gland seems to be + influenced to separate from the blood, or to absorb from the cavities of + the body, or from the atmosphere, its appropriated fluid, by the stimulus + of that fluid on the living gland; and not by mechanical capillary + absorption, nor by chemical affinity. Hence it appears, that each of + these glands must have a peculiar organ to perceive these irritations, + but as these irritations are not succeeded by sensation, they have not + acquired the names of senses.</p> + + <p>However when these glands are excited into motions stronger than + usual, either by the acrimony of their fluids, or by their own + irritability being much increased, then the sensation of pain is produced + in them as in all the other senses of the body; and these pains are all + of different kinds, and hence the glands at this time really become each + a different organ of sense, though these different kinds of pain have + acquired no names.</p> + + <p>Thus a great excess of light does not give the idea of light but of + pain; as in forcibly opening the eye when it is much inflamed. The great + excess of pressure or distention, as when the point of a pin is pressed + upon our skin, produces pain, (and when this pain of the sense of + distention is slighter, it is termed itching, or tickling), without any + idea of solidity or of figure: an excess of heat produces smarting, of + cold another kind of pain; it is probable by this sense of heat the pain + produced by caustic bodies is perceived, and of electricity, as all these + are fluids, that permeate, distend, or decompose the parts that feel + them.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XV">XV</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE CLASSES OF IDEAS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XV_1">I</a>. <a href="#sect_XV_1_1">1</a>. <i>Ideas + received in tribes.</i> <a href="#sect_XV_1_2">2</a>. <i>We combine them + further, or abstract from these tribes.</i> <a href="#sect_XV_1_3">3</a>. + <i>Complex ideas.</i> <a href="#sect_XV_1_4">4</a>. <i>Compounded + ideas.</i> <a href="#sect_XV_1_5">5</a>. <i>Simple ideas, modes, + substances, relations, general ideas.</i> <a href="#sect_XV_1_6">6</a>. + <i>Ideas of reflexion.</i> <a href="#sect_XV_1_7">7</a>. <i>Memory and + imagination imperfectly defined. Ideal presence. Memorandum-rings.</i> <a + href="#sect_XV_2">II</a>. <a href="#sect_XV_2_1">1</a>. <i>Irritative + ideas. Perception.</i> <a href="#sect_XV_2_2">2</a>. <i>Sensitive ideas, + imagination.</i> <a href="#sect_XV_2_3">3</a>. <i>Voluntary ideas, + recollection.</i> <a href="#sect_XV_2_4">4</a>. <i>Associated ideas, + suggestion.</i> <a href="#sect_XV_3">III</a>. <a + href="#sect_XV_3_1">1</a>. <i>Definitions of perception, memory.</i> <a + href="#sect_XV_3_2">2</a>. <i>Reasoning, judgment, doubting, + distinguishing, comparing.</i> <a href="#sect_XV_3_3">3</a>. + <i>Invention.</i> <a href="#sect_XV_3_4">4</a>. <i>Consciousness.</i> <a + href="#sect_XV_3_5">5</a>. <i>Identity.</i> <a href="#sect_XV_3_6">6</a>. + <i>Lapse of time.</i> <a href="#sect_XV_3_7">7</a>. <i>Free-will.</i></p> + +</blockquote> + + <p><a name="sect_XV_1">I</a>. <a name="sect_XV_1_1">1</a>. As the + constituent elements of the material world are only perceptible to our + organs of sense in a state of combination; it follows, that the ideas or + sensual motions excited by them, are never received singly, but ever with + a greater or less degree of combination. So the colours of bodies or + their hardnesses occur with their figures: every smell and taste has its + degree of pungency as well as its peculiar flavour: and each note in + music is combined with the tone of some instrument. It appears from + hence, that we can be sensible of a number of ideas at the same time, + such as the whiteness, hardness, and coldness, of a snow-ball, and can + experience at the same time many irritative ideas of surrounding bodies, + which we do not attend to, as mentioned in Section <a + href="#sect_VII_3_2">VII. 3. 2</a>. But those ideas which belong to the + same sense, seem to be more easily combined into synchronous tribes, than + those which were not received by the same sense, as we can more easily + think of the whiteness and figure of a lump of sugar at the same time, + than the whiteness and sweetness of it.</p> + + <p><a name="sect_XV_1_2">2</a>. As these ideas, or sensual motions, are + thus excited with greater or less degrees of combination; so we have a + power, when we repeat them either by our volition or sensation, to + increase or diminish this degree of combination, that is, to form + compounded ideas from those, which were more simple; and abstract ones + from those, which were more complex, when they were first excited; that + is, we can repeat a part or the whole of those sensual motions, which did + constitute our ideas of perception; and the repetition of which now + constitutes our ideas of recollection, or of imagination.</p> + + <p><a name="sect_XV_1_3">3</a>. Those ideas, which we repeat without + change of the quantity of that combination, with which we first received + them, are called complex ideas, as when you recollect Westminster Abbey, + or the planet Saturn: but it must be observed, that these complex ideas, + thus re-excited by volition, sensation, or association, are seldom + perfect copies of their correspondent perceptions, except in our dreams, + where other external objects do not detract our attention.</p> + + <p><a name="sect_XV_1_4">4</a>. Those ideas, which are more complex than + the natural objects that first excited them, have been called compounded + ideas, as when we think of a sphinx, or griffin.</p> + + <p><a name="sect_XV_1_5">5</a>. And those that are less complex than the + correspondent natural objects, have been termed abstracted ideas: thus + sweetness, and whiteness, and solidity, are received at the same time + from a lump of sugar, yet I can recollect any of these qualities without + thinking of the others, that were excited along with them.</p> + + <p>When ideas are so far abstracted as in the above example, they have + been termed simple by the writers of metaphysics, and seem indeed to be + more complete repetitions of the ideas or sensual motions, originally + excited by external objects.</p> + + <p>Other classes of these ideas, where the abstraction has not been so + great, have been termed, by Mr. Locke, modes, substances, and relations, + but they seem only to differ in their degree of abstraction from the + complex ideas that were at first excited; for as these complex or natural + ideas are themselves imperfect copies of their correspondent perceptions, + so these abstract or general ideas are only still more imperfect copies + of the same perceptions. Thus when I have seen an object but once, as a + rhinoceros, my abstract idea of this animal is the same as my complex + one. I may think more or less distinctly of a rhinoceros, but it is the + very rhinoceros that I saw, or some part or property of him, which recurs + to my mind.</p> + + <p>But when any class of complex objects becomes the subject of + conversation, of which I have seen many individuals, as a castle or an + army, some property or circumstance belonging to it is peculiarly alluded + to; and then I feel in my own mind, that my abstract idea of this complex + object is only an idea of that part, property, or attitude of it, that + employs the present conversation, and varies with every sentence that is + spoken concerning it. So if any one should say, "one may sit upon a horse + safer than on a camel," my abstract idea of the two animals includes only + an outline of the level back of the one, and the gibbosity on the back of + the other. What noise is that in the street?—Some horses trotting + over the pavement. Here my idea of the horses includes principally the + shape and motion of their legs. So also the abstract ideas of goodness + and courage are still more imperfect representations of the objects they + were received from; for here we abstract the material parts, and + recollect only the qualities.</p> + + <p>Thus we abstract so much from some of our complex ideas, that at + length it becomes difficult to determine of what perception they partake; + and in many instances our idea seems to be no other than of the sound or + letters of the word, that stands for the collective tribe, of which we + are said to have an abstracted idea, as noun, verb, chimæra, + apparition.</p> + + <p><a name="sect_XV_1_6">6</a>. Ideas have been divided into those of + perception and those of reflection, but as whatever is perceived must be + external to the organ that perceives it, all our ideas must originally be + ideas of perception.</p> + + <p><a name="sect_XV_1_7">7</a>. Others have divided our ideas into those + of memory, and those of imagination; they have said that a recollection + of ideas in the order they were received constitutes memory, and without + that order imagination; but all the ideas of imagination, excepting the + few that are termed simple ideas, are parts of trains or tribes in the + order they were received; as if I think of a sphinx, or a griffin, the + fair face, bosom, wings, claws, tail, are all complex ideas in the order + they were received: and it behoves the writers, who adhere to this + definition, to determine, how small the trains must be, that shall be + called imagination; and how great those, that shall be called memory.</p> + + <p>Others have thought that the ideas of memory have a greater vivacity + than those of imagination: but the ideas of a person in sleep, or in a + waking reverie, where the trains connected with sensation are + uninterrupted, are more vivid and distinct than those of memory, so that + they cannot be distinguished by this criterion.</p> + + <p>The very ingenious author of the Elements of Criticism has described + what he conceives to be a species of memory, and calls it ideal presence; + but the instances he produces are the reveries of sensation, and are + therefore in truth connections of the imagination, though they are + recalled in the order they were received.</p> + + <p>The ideas connected by association are in common discourse attributed + to memory, as we talk of memorandum-rings, and tie a knot on our + handkerchiefs to bring something into our minds at a distance of time. + And a school-boy, who can repeat a thousand unmeaning lines in Lilly's + Grammar, is said to have a good memory. But these have been already shewn + to belong to the class of association; and are termed ideas of + suggestion.</p> + + <p><a name="sect_XV_2">II</a>. Lastly, the method already explained of + classing ideas into those excited by irritation, sensation, volition, or + association, we hope will be found more convenient both for explaining + the operations of the mind, and for comparing them with those of the + body; and for the illustration and the cure of the diseases of both, and + which we shall here recapitulate.</p> + + <p><a name="sect_XV_2_1">1</a>. Irritative ideas are those, which are + preceded by irritation, which is excited by objects external to the + organs of sense: as the idea of that tree, which either I attend to, or + which I shun in walking near it without attention. In the former case it + is termed perception, in the latter it is termed simply an irritative + idea.</p> + + <p><a name="sect_XV_2_2">2</a>. Sensitive ideas are those, which are + preceded by the sensation of pleasure or pain; as the ideas, which + constitute our dreams or reveries, this is called imagination.</p> + + <p><a name="sect_XV_2_3">3</a>. Voluntary ideas are those, which are + preceded by voluntary exertion, as when I repeat the alphabet backwards: + this is called recollection.</p> + + <p><a name="sect_XV_2_4">4</a>. Associate ideas are those, which are + preceded by other ideas or muscular motions, as when we think over or + repeat the alphabet by rote in its usual order; or sing a tune we are + accustomed to; this is called suggestion.</p> + + <p><a name="sect_XV_3">III</a>. <a name="sect_XV_3_1">1</a>. Perceptions + signify those ideas, which are preceded by irritation and succeeded by + the sensation of pleasure or pain, for whatever excites our attention + interests us; that is, it is accompanied with, pleasure or pain; however + slight may be the degree or quantity of either of them.</p> + + <p>The word memory includes two classes of ideas, either those which, are + preceded by voluntary exertion, or those which are suggested by their + associations with other ideas.</p> + + <p><a name="sect_XV_3_2">2</a>. Reasoning is that operation of the + sensorium, by which we excite two or many tribes of ideas; and then + re-excite the ideas, in which they differ, or correspond. If we determine + this difference, it is called judgment; if we in vain endeavour to + determine it, it is called doubting.</p> + + <p>If we re-excited the ideas, in which they differ, it is called + distinguishing. If we re-excite those in which they correspond, it is + called comparing.</p> + + <p><a name="sect_XV_3_3">3</a>. Invention is an operation of the + sensorium, by which we voluntarily continue to excite one train of ideas, + suppose the design of raising water by a machine; and at the same time + attend to all other ideas, which are connected with this by every kind of + catenation; and combine or separate them voluntarily for the purpose of + obtaining some end.</p> + + <p>For we can create nothing new, we can only combine or separate the + ideas, which we have already received by our perceptions: thus if I wish + to represent a monster, I call to my mind the ideas of every thing + disagreeable and horrible, and combine the nastiness and gluttony of a + hog, the stupidity and obstinacy of an ass, with the fur and awkwardness + of a bear, and call the new combination Caliban. Yet such a monster may + exist in nature, as all his attributes are parts of nature. So when I + wish to represent every thing, that is excellent, and amiable; when I + combine benevolence with cheerfulness, wisdom, knowledge, taste, wit, + beauty of person, and elegance of manners, and associate them in one lady + as a pattern to the world, it is called invention; yet such a person may + exist,—such a person does exist!—It is —— + ——, who is as much a monster as Caliban.</p> + + <p><a name="sect_XV_3_4">4</a>. In respect to consciousness, we are only + conscious of our existence, when we think about it; as we only perceive + the lapse of time, when we attend to it; when we are busied about other + objects, neither the lapse of time nor the consciousness of our own + existence can occupy our attention. Hence, when we think of our own + existence, we only excite abstracted or reflex ideas (as they are + termed), of our principal pleasures or pains, of our desires or + aversions, or of the figure, solidity, colour, or other properties of our + bodies, and call that act of the sensorium a consciousness of our + existence. Some philosopher, I believe it is Des Cartes, has said, "I + think, therefore I exist." But this is not right reasoning, because + thinking is a mode of existence; and it is thence only saying, "I exist, + therefore I exist." For there are three modes of existence, or in the + language of grammarians three kinds of verbs. First, simply I am, or + exist. Secondly, I am acting, or exist in a state of activity, as I move. + Thirdly, I am suffering, or exist in a state of being acted upon, as I am + moved. The when, and the where, as applicable to this existence, depends + on the successive motions of our own or of other bodies; and on their + respective situations, as spoken of Sect. <a href="#sect_XIV_2_5">XIV. 2. + 5</a>.</p> + + <p><a name="sect_XV_3_5">5</a>. Our identity is known by our acquired + habits or catenated trains of ideas and muscular motions; and perhaps, + when we compare infancy with old age, in those alone can our identity be + supposed to exist. For what else is there of similitude between the first + speck of living entity and the mature man?—every deduction of + reasoning, every sentiment or passion, with every fibre of the corporeal + part of our system, has been subject almost to annual mutation; while + some catenations alone of our ideas and muscular actions have continued + in part unchanged.</p> + + <p>By the facility, with which we can in our waking hours voluntarily + produce certain successive trains of ideas, we know by experience, that + we have before reproduced them; that is, we are conscious of a time of + our existence previous to the present time; that is, of our identity now + and heretofore. It is these habits of action, these catenations of ideas + and muscular motions, which begin with life, and only terminate with it; + and which we can in some measure deliver to our posterity; as explained + in Sect. <a href="#sect_XXXIX">XXXIX</a>.</p> + + <p><a name="sect_XV_3_6">6</a>. When the progressive motions of external + bodies make a part of our present catenation of ideas, we attend to the + lapse of time; which appears the longer, the more frequently we thus + attend to it; as when we expect something at a certain hour, which much + interests us, whether it be an agreeable or disagreeable event; or when + we count the passing seconds on a stop-watch.</p> + + <p>When an idea of our own person, or a reflex idea of our pleasures and + pains, desires and aversions, makes a part of this catenation, it is + termed consciousness; and if this idea of consciousness makes a part of a + catenation, which we excite by recollection, and know by the facility + with which we excite it, that we have before experienced it, it is called + identity, as explained above.</p> + + <p><a name="sect_XV_3_7">7</a>. In respect to freewill, it is certain, + that we cannot will to think of a new train of ideas, without previously + thinking of the first link of it; as I cannot will to think of a black + swan, without previously thinking of a black swan. But if I now think of + a tail, I can voluntarily recollect all animals, which have tails; my + will is so far free, that I can pursue the ideas linked to this idea of + tail, as far as my knowledge of the subject extends; but to will without + motive is to will without desire or aversion; which is as absurd as to + feel without pleasure or pain; they are both solecisms 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.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XVI">XVI</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF INSTINCT.</p> + + <div class="contents"> + <div class="stanza"> + <p>Haud equidem credo, quia sit divinitus illis</p> + <p>Ingenium, aut rerum fato prudentia major.—Virg. Georg. L. I. 415.</p> + </div> + </div> +<blockquote class="b1"> + + <p><a href="#sect_XVI_1">I</a>. <i>Instinctive actions defined. Of + connate passions.</i> <a href="#sect_XVI_2">II</a>. <i>Of the sensations + and motions of the fœtus in the womb.</i> <a + href="#sect_XVI_3">III</a>. <i>Some animals are more perfectly formed + than others before nativity. Of learning to walk.</i> <a + href="#sect_XVI_4">IV</a>. <i>Of the swallowing, breathing, sucking, + pecking, and lapping of young animals.</i> <a href="#sect_XVI_5">V</a>. + <i>Of the sense of smell, and its uses to animals. Why cats do not eat + their kittens.</i> <a href="#sect_XVI_6">VI</a>. <i>Of the accuracy of + sight in mankind, and their sense of beauty. Of the sense of touch in + elephants, monkies, beavers, men.</i> <a href="#sect_XVI_7">VII</a>. + <i>Of natural language.</i> <a href="#sect_XVI_8">VIII</a>. <i>The origin + of natural language;</i> <a href="#sect_XVI_8_1">1</a>. <i>the language + of fear;</i> <a href="#sect_XVI_8_2">2</a>. <i>of grief;</i> <a + href="#sect_XVI_8_3">3</a>. <i>of tender pleasure;</i> <a + href="#sect_XVI_8_4">4</a>. <i>of serene pleasure;</i> <a + href="#sect_XVI_8_5">5</a>. <i>of anger;</i> <a + href="#sect_XVI_8_6">6</a>. <i>of attention.</i> <a + href="#sect_XVI_9">IX</a>. <i>Artificial language of turkies, hens, + ducklings, wagtails, cuckoos, rabbits, dogs, and nightingales.</i> <a + href="#sect_XVI_10">X</a>. <i>Of music; of tooth-edge; of a good ear; of + architecture.</i> <a href="#sect_XVI_11">XI</a>. <i>Of acquired + knowledge; of foxes, rooks, fieldfares, lapwings, dogs, cats, horses, + crows, and pelicans.</i> <a href="#sect_XVI_12">XII</a>. <i>Of birds of + passage, dormice, snakes, bats, swallows, quails, ringdoves, stare, + chaffinch, hoopoe, chatterer, hawfinch, crossbill, rails and cranes.</i> + <a href="#sect_XVI_13">XIII</a>. <i>Of birds nests; of the cuckoo; of + swallows nests; of the taylor bird.</i> <a href="#sect_XVI_14">XIV</a>. + <i>Of the old soldier; of haddocks, cods, and dog fish; of the remora; of + crabs, herrings, and salmon.</i> <a href="#sect_XVI_15">XV</a>. <i>Of + spiders, caterpillars, ants, and the ichneumon.</i> <a + href="#sect_XVI_16">XVI</a>. <a href="#sect_XVI_16_1">1</a>. <i>Of + locusts, gnats;</i> <a href="#sect_XVI_16_2">2</a>. <i>bees;</i> <a + href="#sect_XVI_16_3">3</a>. <i>dormice, flies, worms, ants, and + wasps.</i> <a href="#sect_XVI_17">XVII</a>. <i>Of the faculty that + distinguishes man from the brutes.</i></p> + +</blockquote> + + <p><a name="sect_XVI_1">I</a>. All those internal motions of animal + bodies, which contribute to digest their aliment, produce their + secretions, repair their injuries, or increase their growth, are + performed without our attention or consciousness. They exist as well in + our sleep, as in our waking hours, as well in the fœtus during the + time of gestation, as in the infant after nativity, and proceed with + equal regularity in the vegetable as in the animal system. These motions + have been shewn in a former part of this work to depend on the + irritations of peculiar fluids, and as they have never been classed + amongst the instinctive actions of animals, are precluded from our + present disquisition.</p> + + <p>But all those actions of men or animals, that are attended with + consciousness, and seem neither to have been directed by their appetites, + taught by their experience, nor deduced from observation or tradition, + have been referred to the power of instinct. And this power has been + explained to be a <i>divine something</i>, a kind of inspiration; whilst + the poor animal, that possesses it, has been thought little better than + <i>a machine</i>!</p> + + <p>The <i>irksomeness</i>, that attends a continued attitude of the body, + or the <i>pains</i>, that we receive from heat, cold, hunger, or other + injurious circumstances, excite us to <i>general locomotion</i>: and our + senses are so formed and constituted by the hand of nature, that certain + objects present us with pleasure, others with pain, and we are induced to + approach and embrace these, to avoid and abhor those, as such sensations + direct us.</p> + + <p>Thus the palates of some animals are gratefully affected by the + mastication of fruits, others of grains, and others of flesh; and they + are thence instigated to attain, and to consume those materials; and are + furnished with powers of muscular motion, and of digestion proper for + such purposes.</p> + + <p>These <i>sensations</i> and <i>desires</i> constitute a part of our + system, as our <i>muscles</i> and <i>bones</i> constitute another part: + and hence they may alike be termed <i>natural</i> or <i>connate</i>; but + neither of them can properly be termed <i>instinctive</i>: as the word + instinct in its usual acceptation refers only to the <i>actions</i> of + animals, as above explained: the origin of these <i>actions</i> is the + subject of our present enquiry.</p> + + <p>The reader is intreated carefully to attend to this definition of + <i>instinctive actions</i>, lest by using the word instinct without + adjoining any accurate idea to it, he may not only include the natural + desires of love and hunger, and the natural sensations of pain or + pleasure, but the figure and contexture of the body, and the faculty of + reason itself under this general term.</p> + + <p><a name="sect_XVI_2">II</a>. We experience some sensations, and + perform some actions before our nativity; the sensations of cold and + warmth, agitation and rest, fulness and inanition, are instances of the + former; and the repeated struggles of the limbs of the fœtus, which + begin about the middle of gestation, and those motions by which it + frequently wraps the umbilical chord around its neck or body, and even + sometimes ties it on a knot; are instances of the latter. Smellie's + Midwifery, (Vol. I. p. 182.)</p> + + <p>By a due attention to these circumstances many of the actions of young + animals, which at first sight seemed only referable to an inexplicable + instinct, will appear to have been acquired like all other animal + actions, that are attended with consciousness, <i>by the repeated efforts + of our muscles under the conduct of our sensations or desires</i>.</p> + + <p>The chick in the shell begins to move its feet and legs on the sixth + day of incubation (Mattreican, p. 138); or on the seventh day, (Langley); + afterwards they are seen to move themselves gently in the liquid that + surrounds them, and to open and shut their mouths, (Harvei, de Generat. + p. 62, and 197. Form de Poulet. ii. p. 129). Puppies before the membranes + are broken, that involve them, are seen to move themselves, to put out + their tongues, and to open and shut their mouths, (Harvey, Gipson, + Riolan, Haller). And calves lick themselves and swallow many of their + hairs before their nativity: which however puppies do not, (Swammerden, + p. 319. Flemyng Phil. Trans. Ann. 1755. 42). And towards the end of + gestation, the fœtus of all animals are proved to drink part of the + liquid in which they swim, (Haller. Physiol. T. 8. 204). The white of egg + is found in the mouth and gizzard of the chick, and is nearly or quite + consumed before it is hatched, (Harvie de Generat. 58). And the liquor + amnii is found in the mouth and stomach of the human fœtus, and of + calves; and how else should that excrement be produced in the intestines + of all animals, which is voided in great quantity soon after their birth; + (Gipson, Med. Essays, Edinb. V. i. 13. Halleri Physiolog. T. 3. p. 318. + and T. 8). In the stomach of a calf the quantity of this liquid amounted + to about three pints, and the hairs amongst it were of the same colour + with those on its skin, (Blasii Anat. Animal, p.m. 122). These facts are + attested by many other writers of credit, besides those above + mentioned.</p> + + <p><a name="sect_XVI_3">III</a>. It has been deemed a surprising instance + of instinct, that calves and chickens should be able to walk by a few + efforts almost immediately after their nativity: whilst the human infant + in those countries where he is not incumbered with clothes, as in India, + is five or six months, and in our climate almost a twelvemonth, before he + can safely stand upon his feet.</p> + + <p>The struggles of all animals in the womb must resemble their mode of + swimming, as by this kind of motion they can best change their attitude + in water. But the swimming of the calf and chicken resembles their manner + of walking, which they have thus in part acquired before their nativity, + and hence accomplish it afterwards with very few efforts, whilst the + swimming of the human creature resembles that of the frog, and totally + differs from his mode of walking.</p> + + <p>There is another circumstance to be attended to in this affair, that + not only the growth of those peculiar parts of animals, which are first + wanted to secure their subsistence, are in general furthest advanced + before their nativity: but some animals come into the world more + completely formed throughout their whole system than others: and are + thence much forwarder in all their habits of motion. Thus the colt, and + the lamb, are much more perfect animals than the blind puppy, and the + naked rabbit; and the chick of the pheasant, and the partridge, has more + perfect plumage, and more perfect eyes, as well as greater aptitude to + locomotion, than the callow nestlings of the dove, and of the wren. The + parents of the former only find it necessary to shew them their food, and + to teach them to take it up; whilst those of the latter are obliged for + many days to obtrude it into their gaping mouths.</p> + + <p><a name="sect_XVI_4">IV</a>. From the facts mentioned in No. <a + href="#sect_XVI_2">2</a>. of this Section, it is evinced that the + fœtus learns to swallow before its nativity; for it is seen to open + its mouth, and its stomach is found filled with the liquid that surrounds + it. It opens its mouth, either instigated by hunger, or by the + irksomeness of a continued attitude of the muscles of its face; the + liquor amnii, in which it swims, is agreeable to its palate, as it + consists of a nourishing material, (Haller Phys. T. 8. p. 204). It is + tempted to experience its taste further in the mouth, and by a few + efforts learns to swallow, in the same manner as we learn all other + animal actions, which are attended with consciousness, <i>by the repeated + efforts of our muscles under the conduct of our sensations or + volitions</i>.</p> + + <p>The inspiration of air into the lungs is so totally different from + that of swallowing a fluid in which we are immersed, that it cannot be + acquired before our nativity. But at this time, when the circulation of + the blood is no longer continued through the placenta, that suffocating + sensation, which we feel about the precordia, when we are in want of + fresh air, disagreeably affects the infant: and all the muscles of the + body are excited into action to relieve this oppression; those of the + breast, ribs, and diaphragm are found to answer this purpose, and thus + respiration is discovered, and is continued throughout our lives, as + often as the oppression begins to recur. Many infants, both of the human + creature, and of quadrupeds, struggle for a minute after they are born + before they begin to breathe, (Haller Phys. T. 8. p. 400. ib pt. 2. p. + 1). Mr. Buffon thinks the action of the dry air upon the nerves of smell + of new-born animals, by producing an endeavour to sneeze, may contribute + to induce this first inspiration, and that the rarefaction of the air by + the warmth of the lungs contributes to induce expiration, (Hist. Nat. + Tom. 4. p. 174). Which latter it may effect by producing a disagreeable + sensation by its delay, and a consequent effort to relieve it. Many + children sneeze before they respire, but not all, as far as I have + observed, or can learn from others.</p> + + <p>At length, by the direction of its sense of smell, or by the officious + care of its mother, the young animal approaches the odoriferous rill of + its future nourishment, already experienced to swallow. But in the act of + swallowing, it is necessary nearly to close the mouth, whether the + creature be immersed in the fluid it is about to drink, or not: hence, + when the child first attempts to suck, it does not slightly compress the + nipple between its lips, and suck as an adult person would do, by + absorbing the milk; but it takes the whole nipple into its mouth for this + purpose, compresses it between its gums, and thus repeatedly chewing (as + it were) the nipple, presses out the milk, exactly in the same manner as + it is drawn from the teats of cows by the hands of the milkmaid. The + celebrated Harvey observes, that the fœtus in the womb must have + sucked in a part of its nourishment, because it knows how to suck the + minute it is born, as any one may experience by putting a finger between + its lips, and because in a few days it forgets this art of sucking, and + cannot without some difficulty again acquire it, (Exercit. de Gener. + Anim. 48). The same observation is made by Hippocrates.</p> + + <p>A little further experience teaches the young animal to suck by + absorption, as well as by compression; that is, to open the chest as in + the beginning of respiration, and thus to rarefy the air in the mouth, + that the pressure of the denser external atmosphere may contribute to + force out the milk.</p> + + <p>The chick yet in the shell has learnt to drink by swallowing a part of + the white of the egg for its food; but not having experienced how to take + up and swallow solid seeds, or grains, is either taught by the felicitous + industry of its mother; or by many repeated attempts is enabled at length + to distinguish and to swallow this kind of nutriment.</p> + + <p>And puppies, though they know how to suck like other animals from + their previous experience in swallowing, and in respiration; yet are they + long in acquiring the art of lapping with their tongues, which from the + flaccidity of their cheeks, and length of their mouths, is afterwards a + more convenient way for them to take in water.</p> + + <p><a name="sect_XVI_5">V</a>. The senses of smell and taste in many + other animals greatly excel those of mankind, for in civilized society, + as our victuals are generally prepared by others, and are adulterated + with salt, spice, oil, and empyreuma, we do not hesitate about eating + whatever is set before us, and neglect to cultivate these senses: whereas + other animals try every morsel by the smell, before they take it into + their mouths, and by the taste before they swallow it: and are led not + only each to his proper nourishment by this organ of sense, but it also + at a maturer age directs them in the gratification of their appetite of + love. Which may be further understood by considering the sympathies of + these parts described in Class IV. 2. 1. 7. While the human animal is + directed to the object of his love by his sense of beauty, as mentioned + in No. <a href="#sect_XVI_6">VI</a>. of this Section. Thus Virgil. Georg. + III. 250.</p> + + <div class="poem"> + <div class="stanza"> + <p>Nonne vides, ut tota tremor pertentat equorum</p> + <p>Corpora, si tantum notas odor attulit auras?</p> + <p>Nonne canis nidum veneris nasutus odore</p> + <p>Quærit, et erranti trahitur sublambere linguâ?</p> + <p>Respuit at gustum cupidus, labiisque retractis</p> + <p>Elevat os, trepidansque novis impellitur æstris</p> + <p>Inserit et vivum felici vomere semen.—</p> + <p>Quam tenui filo cæcos adnectit amores</p> + <p>Docta Venus, vitæque monet renovare favillam!—ANON.</p> + </div> + </div> + <p>The following curious experiment is related by Galen. "On dissecting a + goat great with young I found a brisk embryon, and having detached it + from the matrix, and snatching it away before it saw its dam, I brought + it into a certain room, where there were many vessels, some filled with + wine, others with oil, some with honey, others with milk, or some other + liquor; and in others were grains and fruits; we first observed the young + animal get upon its feet, and walk; then it shook itself, and afterwards + scratched its side with one of its feet: then we saw it smelling to every + one of these things, that were set in the room; and when it had smelt to + them all, it drank up the milk." L. 6. de locis. cap. 6.</p> + + <p>Parturient quadrupeds, as cats, and bitches, and sows, are led by + their sense of smell to eat the placenta as other common food; why then + do they not devour their whole progeny, as is represented in an antient + emblem of <font class="sc">TIME</font>? This is said sometimes to happen + in the unnatural state in which we confine sows; and indeed nature would + seem to have endangered her offspring in this nice circumstance! But at + this time the stimulus of the milk in the tumid teats of the mother + excites her to look out for, and to desire some unknown circumstance to + relieve her. At the same time the smell of the milk attracts the + exertions of the young animals towards its source, and thus the delighted + mother discovers a new appetite, as mentioned in Sect. <a + href="#sect_XIV_8">XIV. 8</a>. and her little progeny are led to receive + and to communicate pleasure by this most beautiful contrivance.</p> + + <p><a name="sect_XVI_6">VI</a>. But though the human species in some of + their sensations are much inferior to other animals, yet the accuracy of + the sense of touch, which they possess in so eminent a degree, gives them + a great superiority of understanding; as is well observed by the + ingenious Mr. Buffon. The extremities of other animals terminate in + horns, and hoofs, and claws, very unfit for the sensation of touch; + whilst the human hand is finely adapted to encompass its object with this + organ of sense.</p> + + <p>The elephant is indeed endued with a fine sense of feeling at the + extremity of his proboscis, and hence has acquired much more accurate + ideas of touch and of sight than most other creatures. The two following + instances of the sagacity of these animals may entertain the reader, as + they were told me by some gentlemen of distinct observation, and + undoubted veracity, who had been much conversant with our eastern + settlements. First, the elephants that are used to carry the baggage of + our armies, are put each under the care of one of the natives of + Indostan, and whilst himself 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 extremity 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 seduce the wild elephants to come that way, + who fall into these wells, whilst he passes safe between them: and it is + universally observed, that those wild elephants that escape the snare, + pursue the traitor with the utmost vehemence, and if they can overtake + him, which sometimes happens, they always beat him to death.</p> + + <p>The monkey has a hand well enough adapted for the sense of touch, + which contributes to his great facility of imitation; but in taking + objects with his hands, as a stick or an apple, he puts his thumb on the + same side of them with his fingers, instead of counteracting the pressure + of his fingers with it: from this neglect he is much slower in acquiring + the figures of objects, as he is less able to determine the distances or + diameters of their parts, or to distinguish their vis inertiæ from their + hardness. Helvetius adds, that the shortness of his life, his being + fugitive before mankind, and his not inhabiting all climates, combine to + prevent his improvement. (De l'Esprit. T. 1. p.) There is however at this + time an old monkey shewn in Exeter Change, London, who having lost his + teeth, when nuts are given him, takes a stone into his hand, and cracks + them with it one by one; thus using tools to effect his purpose like + mankind.</p> + + <p>The beaver is another animal that makes much use of his hands, and if + we may credit the reports of travellers, is possessed of amazing + ingenuity. This however, M. Buffon affirms, is only where they exist in + large numbers, and in countries thinly peopled with men; while in France + in their solitary state they shew no uncommon ingenuity.</p> + + <p>Indeed all the quadrupeds, that have collar-bones, (claviculæ) use + their fore-limbs in some measure as we use our hands, as the cat, + squirrel, tyger, bear and lion; and as they exercise the sense of touch + more universally than other animals, so are they more sagacious in + watching and surprising their prey. All those birds, that use 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.</p> + + <p>Now as the images, that are painted on the retina of the eye, are no + other than signs, which recall to our imaginations the objects we had + before examined by the organ of touch, as is fully demonstrated by Dr. + Berkley in his treatise on vision; it follows that the human creature has + greatly more accurate and distinct sense of vision than that of any other + animal. Whence as he advances to maturity he gradually acquires a sense + of female beauty, which at this time directs him to the object of his new + passion.</p> + + <p>Sentimental love, as distinguished from the animal passion of that + name, with which it is frequently accompanied, consists in the desire or + sensation of beholding, embracing, and saluting a beautiful object.</p> + + <p>The characteristic 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 so metaphorically, and ought to be + termed agreeable. A Grecian temple may give us the pleasurable idea of + sublimity, a Gothic temple may give us the pleasurable idea of variety, + and a modern house the pleasurable idea of utility; music and poetry may + inspire our love by association of ideas; but none of these, except + metaphorically, can be termed beautiful; as we have no wish to embrace or + salute them.</p> + + <p>Our perception of beauty consists in our recognition by the sense of + vision of those objects, first, which have before inspired our love by + the pleasure, which they have afforded to many of our senses: as to our + sense of warmth, of touch, of smell, of taste, hunger and thirst; and, + secondly, which bear any analogy of form to such objects.</p> + + <p>When the babe, soon after it is born into this cold world, is applied + to its mother's bosom; its sense of perceiving warmth is first agreeably + affected; next its sense of smell is delighted with the odour of her + milk; then its taste is gratified by the flavour of it: afterwards the + appetites of hunger and of thirst afford pleasure by the possession of + their objects, and by the subsequent digestion of the aliment; and, + lastly, the sense of touch is delighted by the softness and smoothness of + the milky fountain, the source of such variety of happiness.</p> + + <p>All these various kinds of pleasure at length become associated with + the form of the mother's breast; which the infant embraces with its + hands, presses with its lips, and watches with its eyes; and thus + acquires more accurate ideas of the form of its mother's bosom, than of + the odour and flavour or warmth, which it perceives by its other senses. + And hence at our maturer years, when any object of vision is presented to + us, which by its waving or spiral lines bears any similitude to the form + of the female bosom, whether it be found in a landscape with soft + gradations of rising and descending surface, or in the forms of some + antique vases, or in other works of the pencil or the chissel, we feel a + general glow of delight, which seems to influence all our senses; and, if + the object be not too large, we experience an attraction to embrace it + with our arms, and to salute it with our lips, as we did in our early + infancy the bosom of our mother. And thus we find, according to the + ingenious idea of Hogarth, that the waving lines of beauty were + originally taken from the temple of Venus.</p> + + <p>This animal attraction is love; which is a sensation, when the object + is present; and a desire, when it is absent. Which constitutes the purest + source of human felicity, the cordial drop in the otherwise vapid cup of + life, and which overpays mankind for the care and labour, which are + attached to the pre-eminence of his situation above other animals.</p> + + <p>It should have been observed, that colour as well as form sometimes + enters into our idea of a beautiful object, as a good complexion for + instance, because a fine or fair colour is in general a sign of health, + and conveys to us an idea of the warmth of the object; and a pale + countenance on the contrary gives an idea of its being cold to the + touch.</p> + + <p>It was before remarked, that young animals use their lips to + distinguish the forms of things, as well as their fingers, and hence we + learn the origin of our inclination to salute beautiful objects with our + lips. For a definition of Grace, see Class III. 1. 2. 4.</p> + + <p><a name="sect_XVI_7">VII</a>. There are two ways by which we become + acquainted with the passions of others: first, by having observed the + effects of them, as of fear or anger, on our own bodies, we know at sight + when others are under the influence of these affections. So when two + cocks are preparing to fight, each feels the feathers rise round his own + neck, and knows from the same sign the disposition of his adversary: and + children long before they can speak, or understand the language of their + parents, may be frightened by an angry countenance, or soothed by smiles + and blandishments.</p> + + <p>Secondly, when we put ourselves into the attitude that any passion + naturally occasions, we soon in some degree acquire that passion; hence + when those that scold indulge themselves in loud oaths, and violent + actions of the arms, they increase their anger by the mode of expressing + themselves: and on the contrary the counterfeited smile of pleasure in + disagreeable company soon brings along with it a portion of the reality, + as is well illustrated by Mr. Burke. (Essay on the Sublime and + Beautiful.)</p> + + <p>This latter method of entering into the passions of others is rendered + of very extensive use by the pleasure we take in imitation, which is + every day presented before our eyes, in the actions of children, and + indeed in all the customs and fashions of the world. From this our + aptitude to imitation, arises what is generally understood by the word + sympathy so well explained by Dr. Smith of Glasgow. Thus the appearance + of a cheerful countenance gives us pleasure, and of a melancholy one + makes us sorrowful. Yawning and sometimes vomiting are thus propagated by + sympathy, and some people of delicate fibres, at the presence of a + spectacle of misery, have felt pain in the same parts of their own + bodies, that were diseased or mangled in the other. Amongst the writers + of antiquity Aristotle thought this aptitude to imitation an essential + property of the human species, and calls man an imitative animal. <span + lang="el" title="To zôon mimômenon" >Το + ζωον + μιμωμενον</span>.</p> + + <p>These then are the natural signs by which we understand each other, + and on this slender basis is built all human language. For without some + natural signs, no artificial ones could have been invented or understood, + as is very ingeniously observed by Dr. Reid. (Inquiry into the Human + Mind.)</p> + + <p><a name="sect_XVI_8">VIII</a>. The origin of this universal language + is a subject of the highest curiosity, the knowledge of which has always + been thought utterly inaccessible. A part of which we shall however here + attempt.</p> + + <p>Light, sound, and odours, are unknown to the fœtus in the womb, + which, except the few sensations and motions already mentioned, sleeps + away its time insensible of the busy world. But the moment he arrives + into day, he begins to experience many vivid pains and pleasures; these + are at the same time attended with certain muscular motions, and from + this their early, and individual association, they acquire habits of + occurring together, that are afterwards indissoluble.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XVI_8_1">1</a>. <i>Of Fear.</i></p> + + <p>As soon as the young animal is born, the first important sensations, + that occur to him, are occasioned by the oppression about his precordia + for want of respiration, and by his sudden transition from ninety-eight + degrees of heat into so cold a climate.—He trembles, that is, he + exerts alternately all the muscles of his body, to enfranchise himself + from the oppression about his bosom, and begins to breathe with frequent + and short respirations; at the same time the cold contracts his red skin, + gradually turning it pale; the contents of the bladder and of the bowels + are evacuated: and from the experience of these first disagreeable + sensations the passion of fear is excited, which is no other than the + expectation of disagreeable sensations. This early association of motions + and sensations persists throughout life; the passion of fear produces a + cold and pale skin, with tremblings, quick respiration, and an evacuation + of the bladder and bowels, and thus constitutes the natural or universal + language of this passion.</p> + + <p>On observing a Canary bird this morning, January 28, 1772, at the + house of Mr. Harvey, near Tutbury, in Derbyshire, I was told it always + fainted away, when its cage was cleaned, and desired to see 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 opened his mouth as if for breath, and respired quick, + stood straighter up on his perch, hung his wings, spread his tail, closed + his eyes, and appeared quite stiff and cataleptic for near half an hour, + and at length with much trembling and deep respirations came gradually to + himself.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XVI_8_2">2</a>. <i>Of Grief.</i></p> + + <p>That the internal membrane of the nostrils may be kept always moist, + for the better perception of odours, there are two canals, that conduct + the tears after they have done their office in moistening and cleaning + the ball of the eye into a sack, which is called the lacrymal sack; and + from which there is a duct, that opens into the nostrils: the aperture of + this duct is formed of exquisite sensibility, and when it is stimulated + by odorous particles, or by the dryness or coldness of the air, the sack + contracts itself, and pours more of its contained moisture on the organ + of smell. By this contrivance the organ is rendered more fit for + perceiving such odours, and is preserved from being injured by those that + are more strong or corrosive. Many other receptacles of peculiar fluids + disgorge their contents, when the ends of their ducts are stimulated; as + the gall bladder, when the contents of the duodenum stimulate the + extremity of the common bile duct: and the salivary glands, when the + termination of their ducts in the mouth are excited by the stimulus of + the food we masticate. Atque vesiculæ seminales suum exprimunt fluidum + glande penis fricatâ.</p> + + <p>The coldness and dryness of the atmosphere, compared with the warmth + and moisture, which the new-born infant had just before experienced, + disagreeably affects the aperture of this lacrymal sack: the tears, that + are contained in this sack, are poured into the nostrils, and a further + supply is secreted by the lacrymal glands, and diffused upon the + eye-balls; as is very visible in the eyes and nostrils of children soon + after their nativity. The same happens to us at our maturer age, for in + severe frosty weather, snivelling and tears are produced by the coldness + and dryness of the air.</p> + + <p>But the lacrymal glands, which separate the tears from the blood, are + situated on the upper external part of the globes of each eye; and, when + a greater quantity of tears are wanted, we contract the forehead, and + bring down the eye-brows, and use many other distortions of the face, to + compress these glands.</p> + + <p>Now as the suffocating sensation, that produces respiration, is + removed almost as soon as perceived, and does not recur again: this + disagreeable irritation of the lacrymal ducts, as it must frequently + recur, till the tender organ becomes used to variety of odours, is one of + the first pains that is repeatedly attended to: and hence throughout our + infancy, and in many people throughout their lives, all disagreeable + sensations are attended with snivelling at the nose, a profusion of + tears, and some peculiar distortions of countenance: according to the + laws of early association before mentioned, which constitutes the natural + or universal language of grief.</p> + + <p>You may assure yourself of the truth of this observation, if you will + attend to what passes, when you read a distressful tale alone; before the + tears overflow your eyes, you will invariably feel a titillation at that + extremity of the lacrymal duct, which terminates in the nostril, then the + compression of the eyes succeeds, and the profusion of tears.</p> + + <p>Linnæus asserts, that the female bear sheds tears in grief; the same + has been said of the hind, and some other animals.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XVI_8_3">3</a>. <i>Of Tender Pleasure.</i></p> + + <p>The first most lively impression of pleasure, that the infant enjoys + after its nativity, is excited by the odour of its mother's milk. The + organ of smell is irritated by this perfume, and the lacrymal sack + empties itself into the nostrils, as before explained, and an increase of + tears is poured into the eyes. Any one may observe this, when very young + infants are about to suck; for at those early periods of life, the + sensation affects the organ of smell, much more powerfully, than after + the repeated habits of smelling has inured it to odours of common + strength: and in our adult years, the stronger smells, though they are at + the same time agreeable to us, as of volatile spirits, continue to + produce an increased secretion of tears.</p> + + <p>This pleasing sensation of smell is followed by the early affection of + the infant to the mother that suckles it, and hence the tender feelings + of gratitude and love, as well as of hopeless grief, are ever after + joined with the titillation of the extremity of the lacrymal ducts, and a + profusion of tears.</p> + + <p>Nor is it singular, that the lacrymal sack should be influenced by + pleasing ideas, as the sight of agreeable food produces the same effect + on the salivary glands. Ac dum vidimus insomniis lascivæ puellæ + simulacrum tenditur penis.</p> + + <p>Lambs shake or wriggle their tails, at the time when they first suck, + to get free of the hard excrement, which had been long lodged in their + bowels. Hence this becomes afterwards a mark of pleasure in them, and in + dogs, and other tailed animals. But cats gently extend and contract their + paws when they are pleased, and purr by drawing in their breath, both + which resemble their manner of sucking, and thus become their language of + pleasure, for these animals having collar-bones use their paws like hands + when they suck, which dogs and sheep do not.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XVI_8_4">4</a>. <i>Of Serene Pleasure.</i></p> + + <p>In the action of sucking, the lips of the infant are closed around the + nipple of its mother, till he has filled his stomach, and the pleasure + occasioned by the stimulus of this grateful food succeeds. Then the + sphincter of the mouth, fatigued by the continued action of sucking, is + relaxed; and the antagonist muscles of the face gently acting, produce + the smile of pleasure: as cannot but be seen by all who are conversant + with children.</p> + + <p>Hence this smile during our lives is associated with gentle pleasure; + it is visible in kittens, and puppies, when they are played with, and + tickled; but more particularly marks the human features. For in children + this expression of pleasure is much encouraged, by their imitation of + their parents, or friends; who generally address them with a smiling + countenance: and hence some nations are more remarkable for the gaiety, + and others for the gravity of their looks.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XVI_8_5">5</a>. <i>Of Anger.</i></p> + + <p>The actions that constitute the mode of fighting, are the immediate + language of anger in all animals; and a preparation for these actions is + the natural language of threatening. Hence the human creature clenches + his fist, and sternly surveys his adversary, as if meditating where to + make the attack; the ram, and the bull, draws himself some steps + backwards, and levels his horns; and the horse, as he most frequently + fights by striking with his hinder feet, turns his heels to his foe, and + bends back his ears, to listen out the place of his adversary, that the + threatened blow may not be ineffectual.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XVI_8_6">6</a>. <i>Of Attention.</i></p> + + <p>The eye takes in at once but half our horizon, and that only in the + day, and our smell informs us of no very distant objects, hence we + confide principally in the organ of hearing to apprize us of danger: when + we hear any the smallest sound, that we cannot immediately account for, + our fears are alarmed, we suspend our steps, hold every muscle still, + open our mouths a little, erect our ears, and listen to gain further + information: and this by habit becomes the general language of attention + to objects of sight, as well as of hearing; and even to the successive + trains of our ideas.</p> + + <p>The natural language of violent pain, which is expressed by writhing + the body, grinning, and screaming; and that of tumultuous pleasure, + expressed in loud laughter; belong to Section <a + href="#sect_XXXIV">XXXIV</a>. on Diseases from Volition.</p> + + <p><a name="sect_XVI_9">IX</a>. It must have already appeared to the + reader, that all other animals, as well as man, are possessed of this + natural language of the passions, expressed in signs or tones; and we + shall endeavour to evince, that those animals, which have preserved + themselves from being enslaved by mankind, and are associated in flocks, + are also possessed of some artificial language, and of some traditional + knowledge.</p> + + <p>The mother-turkey, when she eyes a kite hovering high in air, has + either seen her own parents thrown into fear at his presence, or has by + observation been acquainted with his dangerous designs upon her young. + She becomes agitated with fear, and uses the natural language of that + passion, her young ones catch the fear by imitation, and in an instant + conceal themselves in the grass.</p> + + <p>At the same time that she shews her fears by her gesture and + deportment, she uses a certain exclamation, Koe-ut, Koe-ut, and the young + ones afterwards know, when they hear this note, though they do not see + their dam, that the presence of their adversary is denounced, and hide + themselves as before.</p> + + <p>The wild tribes of birds have very frequent opportunities of knowing + their enemies, by observing the destruction they make among their + progeny, of which every year but a small part escapes to maturity: but to + our domestic birds these opportunities so rarely occur, that their + knowledge of their distant enemies must frequently be delivered by + tradition in the manner above explained, through many generations.</p> + + <p>This note of danger, as well as the other notes of the mother-turkey, + when she calls her flock to their food, or to sleep under her wings, + appears to be an artificial language, both as expressed by the mother, + and as understood by the progeny. For a hen teaches this language with + equal ease to the ducklings, she has hatched from suppositious eggs, and + educates as her own offspring: and the wagtails, or hedge-sparrows, learn + it from the young cuckoo their softer nursling, and supply him with food + long after he can fly about, whenever they hear his cuckooing, which + Linnæus tells us, is his call of hunger, (Syst. Nat.) And all our + domestic animals are readily taught to come to us for food, when we use + one tone of voice, and to fly from our anger, when we use another.</p> + + <p>Rabbits, as they cannot easily articulate sounds, and are formed into + societies, that live under ground, have a very different method of giving + alarm. When danger is threatened, they thump on the ground with one of + their hinder feet, and produce a sound, that can be heard a great way by + animals near the surface of the earth, which would seem to be an + artificial sign both from its singularity and its aptness to the + situation of the animal.</p> + + <p>The rabbits on the island of Sor, near Senegal, have white flesh, and + are well tasted, but do not burrow in the earth, so that we may suspect + their digging themselves houses in this cold climate is an acquired art, + as well as their note of alarm, (Adanson's Voyage to Senegal).</p> + + <p>The barking of dogs is another curious note of alarm, and would seem + to be an acquired language, rather than a natural sign: for "in the + island of Juan Fernandes, the dogs did not attempt to bark, till some + European dogs were put among them, and then they gradually begun to + imitate them, but in a strange manner at first, as if they were learning + a thing that was not natural to them," (Voyage to South America by Don G. + Juan, and Don Ant. de Ulloa. B. 2. c. 4).</p> + + <p>Linnæus also observes, that the dogs of South America do not bark at + strangers, (Syst. Nat.) And the European dogs, that have been carried to + Guinea, are said in three or four generations to cease to bark, and only + howl, like the dogs that are natives of that coast, (World Displayed, + Vol. XVII. p. 26.)</p> + + <p>A circumstance not dissimilar to this, and equally curious, is + mentioned by Kircherus, de Musurgia, in his Chapter de Lusciniis, "That + the young nightingales, that are hatched under other birds, never sing + till they are instructed by the company of other nightingales." And + Jonston affirms, that the nightingales that visit Scotland, have not the + same harmony as those of Italy, (Pennant's Zoology, octavo, p. 255); + which would lead us to suspect that the singing of birds, like human + music, is an artificial language rather than a natural expression of + passion.</p> + + <p><a name="sect_XVI_10">X</a>. Our music like our language, is perhaps + entirely constituted of artificial tones, which by habit suggest certain + agreeable passions. For the same combination of notes and tones do not + excite devotion, love, or poetic melancholy in a native of Indostan and + of Europe. And "the Highlander has the same warlike ideas annexed to the + sound of a bagpipe (an instrument which an Englishman derides), as the + Englishman has to that of a trumpet or fife," (Dr. Brown's Union of + Poetry and Music, p. 58.) So "the music of the Turks is very different + from the Italian, and the people of Fez and Morocco have again a + different kind, which to us appears very rough and horrid, but is highly + pleasing to them," (L'Arte Armoniaca a Giorgio Antoniotto). Hence we see + why the Italian opera does not delight an untutored Englishman; and why + those, who are unaccustomed to music, are more pleased with a tune, the + second or third time they hear it, than the first. For then the same + melodious train of sounds excites the melancholy, they had learned from + the song; or the same vivid combination of them recalls all the mirthful + ideas of the dance and company.</p> + + <p>Even the sounds, that were once disagreeable to us, may by habit be + associated with other ideas, so as to become agreeable. Father Lasitau, + in his account of the Iroquois, says "the music and dance of those + Americans, have something in them extremely barbarous, which at first + disgusts. We grow reconciled to them by degrees, and in the end partake + of them with pleasure, the savages themselves are fond of them to + distraction," (Mœurs des Savages, Tom. ii.)</p> + + <p>There are indeed a few sounds, that we very generally associate with + agreeable ideas, as the whistling of birds, or purring of animals, that + are delighted; and some others, that we as generally associate with + disagreeable ideas, as the cries of animals in pain, the hiss of some of + them in anger, and the midnight howl of beasts of prey. Yet we receive no + terrible or sublime ideas from the lowing of a cow, or the braying of an + ass. Which evinces, that these emotions are owing to previous + associations. So if the rumbling of a carriage in the street be for a + moment mistaken for thunder, we receive a sublime sensation, which ceases + as soon as we know it is the noise of a coach and six.</p> + + <p>There are other disagreeable sounds, that are said to set the teeth on + edge; which, as they have always been thought a necessary effect of + certain discordant notes, become a proper subject of our enquiry. Every + one in his childhood has repeatedly bit a part of the glass or earthen + vessel, in which his food has been given him, and has thence had a very + disagreeable sensation in the teeth, which sensation was designed by + nature to prevent us from exerting them on objects harder than + themselves. The jarring sound produced between the cup and the teeth is + always attendant on this disagreeable sensation: and ever after when such + a sound is accidentally produced by the conflict of two hard bodies, we + feel by association of ideas the concomitant disagreeable sensation in + our teeth.</p> + + <p>Others have in their infancy frequently held the corner of a silk + handkerchief in their mouth, or the end of the velvet cape of their coat, + whilst their companions in play have plucked it from them, and have given + another disagreeable sensation to their teeth, which has afterwards + recurred on touching those materials. And the sight of a knife drawn + along a china plate, though no sound is excited by it, and even the + imagination of such a knife and plate so scraped together, I know by + repeated experience will produce the same disagreeable sensation of the + teeth.</p> + + <p>These circumstances indisputably prove, that this sensation of the + tooth-edge is owing to associated ideas; as it is equally excitable by + sight, touch, hearing, or imagination.</p> + + <p>In respect to the artificial proportions of sound excited by musical + instruments, those, who have early in life associated them with agreeable + ideas, and have nicely attended to distinguish them from each other, are + said to have a good ear, in that country where such proportions are in + fashion: and not from any superior perfection in the organ of hearing, or + any intuitive sympathy between certain sounds and passions.</p> + + <p>I have observed a child to be exquisitely delighted with music, and + who could with great facility learn to sing any tune that he heard + distinctly, and yet whole organ of hearing was so imperfect, that it was + necessary to speak louder to him in common conversation than to + others.</p> + + <p>Our music, like our architecture, seems to have no foundation in + nature, they are both arts purely of human creation, as they imitate + nothing. And the professors of them have only classed those + circumstances, that are most agreeable to the accidental taste of their + age, or country; and have called it Proportion. But this proportion must + always fluctuate, as it rests on the caprices, that are introduced into + our minds by our various modes of education. And these fluctuations of + taste must become more frequent in the present age, where mankind have + enfranchised themselves from the blind obedience to the rules of + antiquity in perhaps every science, but that of architecture. See Sect. + <a href="#sect_XII_7_3">XII. 7. 3</a>.</p> + + <p><a name="sect_XVI_11">XI</a>. There are many articles of knowledge, + which the animals in cultivated countries seem to learn very early in + their lives, either from each other, or from experience, or observation: + one of the most general of these is to avoid mankind. There is so great a + resemblance in the natural language of the passions of all animals, that + we generally know, when they are in a pacific, or in a malevolent humour, + they have the same knowledge of us; and hence we can scold them from us + by some tones and gestures, and could possibly attract them to us by + others, if they were not already apprized of our general malevolence + towards them. Mr. Gmelin, Professor at Petersburg, assures us, that in + his journey into Siberia, undertaken by order of the Empress of Russia, + he saw foxes, that expressed no fear of himself or companions, but + permitted him to come quite near them, having never seen the human + creature before. And Mr. Bongainville relates, that at his arrival at the + Malouine, or Falkland's Islands, which were not inhabited by men, all the + animals came about himself and his people; the fowls settling upon their + heads and shoulders, and the quadrupeds running about their feet. From + the difficulty of acquiring the confidence of old animals, and the ease + of taming young ones, it appears that the fear, they all conceive at the + sight of mankind, is an acquired article of knowledge.</p> + + <p>This knowledge is more nicely understood by rooks, who are formed into + societies, and build, as it were, cities over our heads; they evidently + distinguish, that the danger is greater when a man is armed with a gun. + Every one has seen this, who in the spring of the year has walked under a + rookery with a gun in his hand: the inhabitants of the trees rise on + their wings, and scream to the unfledged young to shrink into their nests + from the sight of the enemy. The vulgar observing this circumstance so + uniformly to occur, assert that rooks can smell gun-powder.</p> + + <p>The fieldfares, (turdus pilarus) which breed in Norway, and come + hither in the cold season for our winter berries; as they are associated + in flocks, and are in a foreign country, have evident marks of keeping a + kind of watch, to remark and announce the appearance of danger. On + approaching a tree, that is covered with them, they continue fearless + till one at the extremity of the bush rising on his wings gives a loud + and peculiar note of alarm, when they all immediately fly, except one + other, who continues till you approach still nearer, to certify as it + were the reality of the danger, and then he also flies off repeating the + note of alarm.</p> + + <p>And in the woods about Senegal there is a bird called uett-uett by the + negroes, and squallers by the French, which, as soon as they see a man, + set up a loud scream, and keep flying round him, as if their intent was + to warn other birds, which upon hearing the cry immediately take wing. + These birds are the bane of sportsmen, and frequently put me into a + passion, and obliged me to shoot them, (Adanson's Voyage to Senegal, 78). + For the same intent the lesser birds of our climate seem to fly after a + hawk, cuckoo, or owl, and scream to prevent their companions from being + surprised by the general enemies of themselves, or of their eggs and + progeny.</p> + + <p>But the lapwing, (charadrius pluvialis Lin.) when her unfledged + offspring run about the marshes, where they were hatched, not only gives + the note of alarm at the approach of men or dogs, that her young may + conceal themselves; but flying and screaming near the adversary, she + appears more felicitous and impatient, as he recedes from her family, and + thus endeavours to mislead him, and frequently succeeds in her design. + These last instances are so apposite to the situation, rather than to the + natures of the creatures, that use them; and are so similar to the + actions of men in the same circumstances, that we cannot but believe, + that they proceed from a similar principle.</p> + + <p>Miss M.E. Jacson acquainted me, that she witnessed this autumn an + agreeable instance of sagacity in a little bird, which seemed to use the + means to obtain an end; the bird repeatedly hopped upon a poppy-stem, and + shook the head with its bill, till many seeds were scattered, then it + settled on the ground, and eat the seeds, and again repeated the same + management. Sept. 1, 1794.</p> + + <p>On the northern coast of Ireland a friend of mine saw above a hundred + crows at once preying upon muscles; each crow took a muscle up into the + air twenty or forty yards high, and let it fall on the stones, and thus + by breaking the shell, got possession of the animal.—A certain + philosopher (I think it was Anaxagoras) walking along the sea-shore to + gather shells, one of these unlucky birds mistaking his bald head for a + stone, dropped a shell-fish upon it, and killed at once a philosopher and + an oyster.</p> + + <p>Our domestic animals, that have some liberty, are also possessed of + some peculiar traditional knowledge: dogs and cats have been forced into + each other's society, though naturally animals of a very different kind, + and have hence learned from each other to eat dog's grass (agrostis + canina) when they are sick, to promote vomiting. I have seen a cat + mistake the blade of barley for this grass, which evinces it is an + acquired knowledge. They have also learnt of each other to cover their + excrement and urine;—about a spoonful of water was spilt upon my + hearth from the tea-kettle, and I observed a kitten cover it with ashes. + Hence this must also be an acquired art, as the creature mistook the + application of it.</p> + + <p>To preserve their fur clean, and especially their whiskers, cats wash + their faces, and generally quite behind their ears, every time they eat. + As they cannot lick those places with their tongues, they first wet the + inside of the leg with saliva, and then repeatedly wash their faces with + it, which must originally be an effect of reasoning, because a means is + used to produce an effect; and seems afterwards to be taught or acquired + by imitation, like the greatest part of human arts.</p> + + <p>These animals seem to possess something like an additional sense by + means of their whiskers; which have perhaps some analogy to the antennæ + of moths and butterflies. The whiskers of cats consist not only of the + long hairs on their upper lips, but they have also four or five long + hairs standing up from each eyebrow, and also two or three on each cheek; + all which, when the animal erects them, make with their points so many + parts of the periphery of a circle, of an extent at least equal to the + circumference of any part of their own bodies. With this instrument, I + conceive, by a little experience, they can at once determine, whether any + aperture amongst hedges or shrubs, in which animals of this genus live in + their wild state, is large enough to admit their bodies; which to them is + a matter of the greatest consequence, whether pursuing or pursued. They + have likewise a power of erecting and bringing forward the whiskers on + their lips; which probably is for the purpose of feeling, whether a dark + hole be further permeable.</p> + + <p>The antennæ, or horns, of butterflies and moths, who have awkward + wings, the minute feathers of which are very liable to injury, serve, I + suppose, a similar purpose of measuring, as they fly or creep amongst the + leaves of plants and trees, whither their wings can pass without touching + them.</p> + + <p>Mr. Leonard, a very intelligent friend of mine, saw a cat catch a + trout by darting upon it in a deep clear water at the mill at Weaford, + near Lichfield. The cat belonged to Mr. Stanley, who had often seen her + catch fish in the same manner in summer, when the mill-pool was drawn so + low, that the fish could be seen. I have heard of other cats taking fish + in shallow water, as they stood on the bank. This seems a natural art of + taking their prey in cats, which their acquired delicacy by domestication + has in general prevented them from using, though their desire of eating + fish continues in its original strength.</p> + + <p>Mr. White, in his ingenious History of Selbourn, was witness to a + cat's suckling a young hare, which followed her about the garden, and + came jumping to her call of affection. At Elford, near Lichfield, the + Rev. Mr. Sawley had taken the young ones out of a hare, which was shot; + they were alive, and the cat, who had just lost her own kittens, carried + them away, as it was supposed, to eat them; but it presently appeared, + that it was affection not hunger which incited her, as she suckled them, + and brought them up as their mother.</p> + + <p>Other instances of the mistaken application of what has been termed + instinct may be observed in flies in the night, who mistaking a candle + for day-light, approach and perish in the flame. So the putrid smell of + the stapelia, or carrion-flower, allures the large flesh-fly to deposit + its young worms on its beautiful petals, which perish there for want of + nourishment. This therefore cannot be a necessary instinct, because the + creature mistakes the application of it.</p> + + <p>Though in this country horses shew little vestiges of policy, yet in + the deserts of Tartary, and Siberia, when hunted by the Tartars they are + seen to form a kind of community, set watches to prevent their being + surprised, and have commanders, who direct, and hasten their flight, + Origin of Language, Vol. I. p. 212. In this country, where four or five + horses travel in a line, the first always points his ears forward, and + the last points his backward, while the intermediate ones seem quite + careless in this respect; which seems a part of policy to prevent + surprise. As all animals depend most on the ear to apprize them of the + approach of danger, the eye taking in only half the horizon at once, and + horses possess a great nicety of this sense; as appears from their mode + of fighting mentioned No. <a href="#sect_XVI_8_5">8. 5</a>. of this + Section, as well as by common observation.</p> + + <p>There are some parts of a horse, which he cannot conveniently rub, + when they itch, as about the shoulder, which he can neither bite with his + teeth, nor scratch with his hind foot; when this part itches, he goes to + another horse, and gently bites him in the part which he wishes to be + bitten, which is immediately done by his intelligent friend. I once + observed a young foal thus bite its large mother, who did not choose to + drop the grass she had in her mouth, and rubbed her nose against the + foal's neck instead of biting it; which evinces that she knew the design + of her progeny, and was not governed by a necessary instinct to bite + where she was bitten.</p> + + <p>Many of our shrubs, which would otherwise afford an agreeable food to + horses, are armed with thorns or prickles, which secure them from those + animals; as the holly, hawthorn, gooseberry, gorse. In the extensive + moorlands of Staffordshire, the horses have learnt to stamp upon a + gorse-bush with one of their fore-feet for a minute together, and when + the points are broken, they eat it without injury. The horses in the new + forest in Hampshire are affirmed to do the same by Mr. Gilpin. Forest + Scenery, II. 251, and 112. Which is an art other horses in the fertile + parts of the country do not possess, and prick their mouths till they + bleed, if they are induced by hunger or caprice to attempt eating + gorse.</p> + + <p>Swine have a sense of touch as well as of smell at the end of their + nose, which they use as a hand, both to root up the soil, and to turn + over and examine objects of food, somewhat like the proboscis of an + elephant. As they require shelter from the cold in this climate, they + have learnt to collect straw in their mouths to make their nest, when the + wind blows cold; and to call their companions by repeated cries to assist + in the work, and add to their warmth by their numerous bedfellows. Hence + these animals, which are esteemed so unclean, have also learned never to + befoul their dens, where they have liberty, with their own excrement; an + art, which cows and horses, which have open hovels to run into, have + never acquired. I have observed great sagacity in swine; but the short + lives we allow them, and their general confinement, prevents their + improvement, which might probably be otherwise greater than that of + dogs.</p> + + <p>Instances of the sagacity and knowledge of animals are very numerous + to every observer, and their docility in learning various arts from + mankind, evinces that they may learn similar arts from their own species, + and thus be possessed of much acquired and traditional knowledge.</p> + + <p>A dog whose natural prey is sheep, is taught by mankind, not only to + leave them unmolested, but to guard them; and to hunt, to set, or to + destroy other kinds of animals, as birds, or vermin; and in some + countries to catch fish, in others to find truffles, and to practise a + great variety of tricks; is it more surprising that the crows should + teach each other, that the hawk can catch less birds, by the superior + swiftness of his wing, and if two of them follow him, till he succeeds in + his design, that they can by force share a part of the capture? This I + have formerly observed with attention and astonishment.</p> + + <p>There is one kind of pelican mentioned by Mr. Osbeck, one of Linnæus's + travelling pupils (the pelicanus aquilus), whose food is fish; and which + it takes from other birds, because it is not formed to catch them itself; + hence it is called by the English a Man-of-war-bird, Voyage to China, p. + 88. There are many other interesting anecdotes of the pelican and + cormorant, collected from authors of the best authority, in a + well-managed Natural History for Children, published by Mr. Galton. + Johnson. London.</p> + + <p>And the following narration from the very accurate Mons. Adanson, in + his Voyage to Senegal, may gain credit with the reader: as his employment + in this country was solely to make observations in natural history. On + the river Niger, in his road to the island Griel, he saw a great number + of pelicans, or wide throats. "They moved with great state like swans + upon the water, and are the largest bird next to the ostrich; the bill of + the one I killed was upwards of a foot and half long, and the bag + fastened underneath it held two and twenty pints of water. They swim in + flocks, and form a large circle, which they contract afterwards, driving + the fish before them with their legs: when they see the fish in + sufficient number confined in this space, they plunge their bill wide + open into the water, and shut it again with great quickness. They thus + get fish into their throat-bag, which they eat afterwards on shore at + their leisure." P. 247.</p> + + <p><a name="sect_XVI_12">XII</a>. The knowledge and language of those + birds, that frequently change their climate with the seasons, is still + more extensive: as they perform these migrations in large societies, and + are less subject to the power of man, than the resident tribes of birds. + They are said to follow a leader during the day, who is occasionally + changed, and to keep a continual cry during the night to keep themselves + together. It is probable that these emigrations were at first undertaken + as accident directed, by the more adventurous of their species, and + learned from one another like the discoveries of mankind in navigation. + The following circumstances strongly support this opinion.</p> + + <p><a name="sect_XVI_12_1">1</a>. Nature has provided these animals, in + the climates where they are produced, with another resource: when the + season becomes too cold for their constitutions, or the food they were + supported with ceases to be supplied, I mean that of sleeping. Dormice, + snakes, and bats, have not the means of changing their country; the two + former from the want of wings, and the latter from his being not able to + bear the light of the day. Hence these animals are obliged to make use of + this resource, and sleep during the winter. And those swallows that have + been hatched too late in the year to acquire their full strength of + pinion, or that have been maimed by accident or disease, have been + frequently found in the hollows of rocks on the sea coasts, and even + under water in this torpid state, from which they have been revived by + the warmth of a fire. This torpid state of swallows is testified by + innumerable evidences both of antient and modern names. Aristotle + speaking of the swallows says, "They pass into warmer climates in winter, + if such places are at no great distance; if they are, they bury + themselves in the climates where they dwell," (8. Hist. c. 16. See also + Derham's Phys. Theol. v. ii. p. 177.)</p> + + <p>Hence their emigrations cannot depend on a <i>necessary</i> instinct, + as the emigrations themselves are not <i>necessary</i>.</p> + + <p><a name="sect_XVI_12_2">2</a>. When the weather becomes cold, the + swallows in the neighbourhood assemble in large flocks; that is, the + unexperienced attend those that have before experienced the journey they + are about to undertake: they are then seen some time to hover on the + coast, till there is calm whether, or a wind, that suits the direction of + their flight. Other birds of passage have been drowned by thousands in + the sea, or have settled on ships quite exhausted with fatigue. And + others, either by mistaking their course, or by distress of weather, have + arrived in countries where they were never seen before: and thus are + evidently subject to the same hazards that the human species undergo, in + the execution of their artificial purposes.</p> + + <p><a name="sect_XVI_12_3">3</a>. The same birds are emigrant from some + countries and not so from others: the swallows were seen at Goree in + January by an ingenious philosopher of my acquaintance, and he was told + that they continued there all the year; as the warmth of the climate was + at all seasons sufficient for their own constitutions, and for the + production of the flies that supply them with nourishment. Herodotus + says, that in Libya, about the springs of the Nile, the swallows continue + all the year. (L. 2.)</p> + + <p>Quails (tetrao corturnix, Lin.) are birds of passage from the coast of + Barbary to Italy, and have frequently settled in large shoals on ships + fatigued with their flight. (Ray, Wisdom of God, p. 129. Derham. Physic. + Theol. v. ii. p. 178,) Dr. Ruffel, in his History of Aleppo, observes + that the swallows visit that country about the end of February, and + having hatched their young disappear about the end of July; and returning + again about the beginning of October, continue about a fortnight, and + then again disappear. (P. 70.)</p> + + <p>When my late friend Dr. Chambres, of Derby, was on the island of + Caprea in the bay of Naples, he was informed that great flights of quails + annually settle on that island about the beginning of May, in their + passage from Africa to Europe. And that they always come when the + south-east wind blows, are fatigued when they rest on this island, and + are taken in such amazing quantities and sold to the Continent, that the + inhabitants pay the bishop his stipend out of the profits arising from + the sale of them.</p> + + <p>The flights of these birds across the Mediterranean are recorded near + three thousand years ago. "There went forth a wind from the Lord and + brought quails from the sea, 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.)</p> + + <p>In our country, Mr. Pennant informs us, that some quails migrate, and + others only remove from the internal parts of the island to the coasts, + (Zoology, octavo, 210.) Some of the ringdoves and stares breed here, + others migrate, (ibid. 510, ii.) And the slender billed small birds do + not all quit these kingdoms in the winter, though the difficulty of + procuring the worms and insects, that they feed on, supplies the same + reason for migration to them all, (ibid. 511.)</p> + + <p>Linnæus has observed, that in Sweden the female chaffinches quit that + country in September, migrating into Holland, and leave their mates + behind till their return in spring. Hence he has called them Fringilla + cælebs, (Amæn. Acad. ii. 42. iv. 595.) Now in our climate both sexes of + them are perennial birds. And Mr. Pennant observes that the hoopoe, + chatterer, hawfinch, and crossbill, migrate into England so rarely, and + at such uncertain times, as not to deserve to be ranked among our birds + of passage, (ibid. 511.)</p> + + <p>The water fowl, as geese and ducks, are better adapted for long + migrations, than the other tribes of birds, as, when the weather is calm, + they can not only rest themselves, or sleep upon the ocean, but possibly + procure some kind of food from it.</p> + + <p>Hence in Siberia, as soon as the lakes are frozen, the water fowl, + which are very numerous, all disappear, and are supposed to fly to warmer + climates, except the rail, which, from its inability for long flights, + probably sleeps, like our bat, in their winter. The following account + from the Journey of Professor Gmelin, may entertain the reader. "In the + neighbourhood of Krasnoiark, amongst many other emigrant water fowls, we + observed a great number of rails, which when pursued never took flight, + but endeavoured to escape by running. We enquired how these birds, that + could not fly, could retire into other countries in the winter, and were + told, both by the Tartars and Assanians, that they well knew those birds + could not alone pass into other countries: 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."</p> + +<p class="center" style="margin-top: 2em;"><i>Recapitulation.</i></p> + + <p>1. All birds of passage can exist in the climates, where they are + produced.</p> + + <p>2. They are subject in their migrations to the same accidents and + difficulties, that mankind are subject to in navigation.</p> + + <p>3. The same species of birds migrate from some countries, and are + resident in others.</p> + + <p>From all these circumstances it appears that the migrations of birds + are not produced by a necessary instinct, but are accidental + improvements, like the arts among mankind, taught by their cotemporaries, + or delivered by tradition from one generation of them to another.</p> + + <p><a name="sect_XVI_13">XIII</a>. In that season of the year which + supplies the nourishment proper for the expected brood, the birds enter + into a contract of marriage, and with joint labour construct a bed for + the reception of their offspring. Their choice of the proper season, + their contracts of marriage, and the regularity with which they construct + their nests, have in all ages excited the admiration of naturalists; and + have always been attributed to the power of instinct, which, like the + occult qualities of the antient philosophers, prevented all further + enquiry. We shall consider them in their order.</p> + +<p class="center" style="margin-top: 2em;"><i>Their Choice of the Season.</i></p> + + <p>Our domestic birds, that are plentifully supplied throughout the year + with their adapted food, and are covered with houses from the inclemency + of the weather, lay their eggs at any season: which evinces that the + spring of the year is not pointed out to them by a necessary + instinct.</p> + + <p>Whilst the wild tribes of birds choose this time of the year from + their acquired knowledge, that the mild temperature of the air is more + convenient for hatching their eggs, and is soon likely to supply that + kind of nourishment, that is wanted for their young.</p> + + <p>If the genial warmth of the spring produced the passion of love, as it + expands the foliage of trees, all other animals should feel its influence + as well as birds: but, the viviparous creatures, as they suckle their + young, that is, as they previously digest the natural food, that it may + better suit the tender stomachs of their offspring, experience the + influence of this passion at all seasons of the year, as cats and + bitches. The graminivorous animals indeed generally produce their young + about the time when grass is supplied in the greatest plenty, but this is + without any degree of exactness, as appears from our cows, sheep, and + hares, and may be a part of the traditional knowledge, which they learn + from the example of their parents.</p> + +<p class="center" style="margin-top: 2em;"><i>Their Contracts of Marriage.</i></p> + + <p>Their mutual passion, and the acquired knowledge, that their joint + labour is necessary to procure sustenance for their numerous family, + induces the wild birds to enter into a contract of marriage, which does + not however take place among the ducks, geese, and fowls, that are + provided with their daily food from our barns.</p> + + <p>An ingenious philosopher has lately denied, that animals can enter + into contracts, and thinks this an essential difference between them and + the human creature:—but does not daily observation convince us, + that they form contracts of friendship with each other, and with mankind? + When puppies and kittens play together, is there not a tacit contract, + that they will not hurt each other? And does not your favorite dog expect + you should give him his daily food, for his services and attention to + you? And thus barters his love for your protection? In the same manner + that all contracts are made amongst men, that do not understand each + others arbitrary language.</p> + +<p class="center" style="margin-top: 2em;"><i>Construction of their Nests.</i></p> + + <p><a name="sect_XVI_13_1">1</a>. They seem to be instructed how to build + their nests from their observation of that, in which they were educated, + and from their knowledge of those things, that are most agreeable to + their touch in respect: to warmth, cleanliness, and stability. They + choose their situations from their ideas of safety from their enemies, + and of shelter from the weather. Nor is the colour of their nests a + circumstance unthought of; the finches, that build in green hedges, cover + their habitations with green moss; the swallow or martin, that builds + against rocks and houses, covers her's with clay, whilst the lark chooses + vegetable straw nearly of the colour of the ground she inhabits: by this + contrivance, they are all less liable to be discovered by their + adversaries.</p> + + <p><a name="sect_XVI_13_2">2</a>. Nor are the nests of the same species + of birds constructed always of the same materials, nor in the same form; + which is another circumstance that ascertains, that they are led by + observation.</p> + + <p>In the trees before Mr. Levet's house in Lichfield, there are annually + nests built by sparrows, a bird which usually builds under the tiles of + houses, or the thatch of barns. Not finding such convenient situations + for their nests, they build a covered nest bigger than a man's head, with + an opening like a mouth at the side, resembling that of a magpie, except + that it is built with straw and hay, and lined with feathers, and so + nicely managed as to be a defence against both wind and rain.</p> + + <p>The following extract from a Letter of the Rev. Mr. J. Darwin, of + Carleton Scroop in Lincolnshire, authenticates a curious fact of this + kind. "When I mentioned to you the circumstance of crows or rooks + building in the spire of Welbourn church, you expressed a desire of being + well informed of the certainty of the fact. Welbourn is situated in the + road from Grantham to Lincoln on the Cliff row; I yesterday took a ride + thither, and enquired of the rector, Mr. Ridgehill, whether the report + was true, that rooks built in the spire of his church. He assured me it + was true, and that they had done so time immemorial, as his parishioners + affirmed. There was a common tradition, he said, that formerly a rookery + in some high trees adjoined the church yard, which being cut down + (probably in the spring, the building season), the rooks removed to the + church, and built their nests on the outside of the spire on the tops of + windows, which by their projection a little from the spire made them + convenient room, but that they built also on the inside. I saw two nests + made with sticks on the outside, and in the spires, and Mr. Ridgehill + said there were always a great many.</p> + + <p>"I spent the day with Mr. Wright, a clergyman, at Fulbeck, near + Welbourn, and in the afternoon Dr. Ellis of Headenham, about two miles + from Welbourn, drank tea at Mr. Wright's, who said he remembered, when + Mr. Welby lived at Welbourn, that he received a letter from an + acquaintance in the west of England, desiring an answer, whether the + report of rooks building in Welbourn church was true, as a wager was + depending on that subject; to which he returned an answer ascertaining + the fact, and decided the wager." Aug. 30, 1794.</p> + + <p>So the jackdaw (corvus monedula) generally builds in church-steeples, + or under the roofs of high houses; but at Selbourn, in Southamptonshire, + where towers and steeples are not sufficiently numerous, these birds + build in forsaken rabbit burrows. See a curious account of these + subterranean nests in White's History of Selbourn, p. 59. Can the skilful + change of architecture in these birds and the sparrows above mentioned be + governed by instinct? Then they must have two instincts, one for common, + and the other for extraordinary occasions.</p> + + <p>I have seen green worsted in a nest, which no where exists in nature: + and the down of thistles in those nests, that were by some accident + constructed later in the summer, which material could not be procured for + the earlier nests: in many different climates they cannot procure the + same materials, that they use in ours. And it is well known, that the + canary birds, that are propagated in this country, and the finches, that + are kept tame, will build their nests of any flexile materials, that are + given them. Plutarch, in his Book on Rivers, speaking of the Nile, says, + "that the swallows collect a material, when the waters recede, with which + they form nests, that are impervious to water." And in India there is a + swallow that collects a glutinous substance for this purpose, whose nest + is esculent, and esteemed a principal rarity amongst epicures, (Lin. + Syst. Nat.) Both these must be constructed of very different materials + from those used by the swallows of our country.</p> + + <p>In India the birds exert more artifice in building their nests on + account of the monkeys and snakes: some form their pensile nests in the + shape of a purse, deep and open at top; others with a hole in the side; + and others, still more cautious, with an entrance at the very bottom, + forming their lodge near the summit. But the taylor-bird will not ever + trust its nest to the extremity of a tender twig, but makes one more + advance to safety by fixing it to the leaf itself. It picks up a dead + leaf, and sews it to the side of a living one, its slender bill being its + needle, and its thread some fine fibres; the lining consists of feathers, + gossamer, and down; its eggs are white, the colour of the bird light + yellow, its length three inches, its weight three sixteenths of an ounce; + so that the materials of the nest, and the weight of the bird, are not + likely to draw down an habitation so slightly suspended. A nest of this + bird is preserved in the British Museum, (Pennant's Indian Zoology). This + calls to one's mind the Mosaic account of the origin of mankind, the + first dawning of art there ascribed to them, is that of sewing leaves + together. For many other curious kinds of nests see Natural History for + Children, by Mr. Galton. Johnson. London. Part I. p. 47. Gen. + Oriolus.</p> + + <p><a name="sect_XVI_13_3">3</a>. Those birds that are brought up by our + care, and have had little communication with others of their own species, + are very defective in this acquired knowledge; they are not only very + awkward in the construction of their nests, but generally scatter their + eggs in various parts of the room or cage, where they are confined, and + seldom produce young ones, till, by failing in their first attempt, they + have learnt something from their own observation.</p> + + <p><a name="sect_XVI_13_4">4</a>. During the time of incubation birds are + said in general to turn their eggs every day; some cover them, when they + leave the nest, as ducks and geese; in some the male is said to bring + food to the female, that she may have less occasion of absence, in others + he is said to take her place, when she goes in quest of food; and all of + them are said to leave their eggs a shorter time in cold weather than in + warm. In Senegal the ostrich sits on her eggs only during the night, + leaving them in the day to the heat of the sun; but at the Cape of Good + Hope, where the heat is less, she sits on them day and night.</p> + + <p>If it should be asked, what induces a bird to sit weeks on its first + eggs unconscious that a brood of young ones will be the product? The + answer must be, that it is the same passion that induces the human mother + to hold her offspring whole nights and days in her fond arms, and press + it to her bosom, unconscious of its future growth to sense and manhood, + till observation or tradition have informed her.</p> + + <p><a name="sect_XVI_13_5">5</a>. And as many ladies are too refined to + nurse their own children, and deliver them to the care and provision of + others; so is there one instance of this vice in the feathered world. The + cuckoo in some parts of England, as I am well informed by a very distinct + and ingenious gentleman, hatches and educates her own young; whilst in + other parts she builds no nest, but uses that of some lesser bird, + generally either of the wagtail, or hedge sparrow, and depositing one egg + in it, takes no further care of her progeny.</p> + + <p>As the Rev. Mr. Stafford was walking in Glosop Dale, in the Peak of + Derbyshire, he saw a cuckoo rise from its nest. The nest was on the stump + of a tree, that had been some time felled, among some chips that were in + part turned grey, so as much to resemble the colour of the bird, in this + nest were two young cuckoos: tying a string about the leg of one of them, + he pegged the other end of it to the ground, and very frequently for many + days beheld the old cuckoo feed these her young, as he stood very near + them.</p> + + <p>The following extract of a Letter from the Rev. Mr. Wilmot, of Morley, + near Derby, strengthens the truth of the fact above mentioned, of the + cuckoo sometimes making a nest, and hatching her own young.</p> + + <p>"In the beginning of July 1792, I was attending some labourers on my + farm, when one of them said to me, "There is a bird's nest upon one of + the Coal-slack Hills; the bird is now sitting, and is exactly like a + cuckoo. They say that cuckoo's never hatch their own eggs, otherwise I + should have sworn it was one." He took me to the spot, it was in an open + fallow ground; the bird was upon the nest, I stood and observed her some + time, and was perfectly satisfied it was a cuckoo; I then put my hand + towards her, and she almost let me touch her before she rose from the + nest, which she appeared to quit with great uneasiness, skimming over the + ground in the manner that a hen partridge does when disturbed from a new + hatched brood, and went only to a thicket about forty or fifty yards from + the nest; and continued there as long as I staid to observe her, which + was not many minutes. In the nest, which was barely a hole scratched out + of the coal-slack in the manner of a plover's nest, I observed three + eggs, but did not touch them. As I had labourers constantly at work in + that field, I went thither every day, and always looked to see if the + bird was there, but did not disturb her for seven or eight days, when I + was tempted to drive her from the nest, and found <i>two</i> young ones, + that appeared to have been hatched some days, but there was no appearance + of the third egg. I then mentioned this extraordinary circumstance (for + such I thought it) to Mr. and Mrs. Holyoak of Bidford Grange, + Warwickshire, and to Miss M. Willes, who were on a visit at my house, and + who all went to see it. Very lately I reminded Mr. Holyoak of it, who + told me he had a perfect recollection of the whole, and that, considering + it a curiosity, he walked to look at it several times, was perfectly + satisfied as to its being a cuckoo, and thought her more attentive to her + young, than any other bird he ever observed, having always found her + brooding her young. In about a week after I first saw the young ones, one + of them was missing, and I rather suspected my plough-boys having taken + it; though it might possibly have been taken by a hawk, some time when + the old one was seeking food. I never found her off her nest but once, + and that was the last time I saw the remaining young one, when it was + almost full feathered. I then went from home for two or three days, and, + when I returned, the young one was gone, which I take for granted had + flown. Though during this time I frequently saw cuckoos in the thicket I + mention, I never observed any one, that I supposed to be the cock-bird, + paired with this hen."</p> + + <p>Nor is this a new observation, though it is entirely overlooked by the + modern naturalists, for Aristotle speaking of the cuckoo, asserts that + she sometimes builds her nest among broken rocks, and on high mountains, + (L. 6. H. c. 1.) but adds in another place that she generally possesses + the nest of another bird, (L. 6. H. c. 7.) And Niphus says that cuckoos + rarely build for themselves, most frequently laying their eggs in the + nests of other birds, (Gesner, L. 3. de Cuculo.)</p> + + <p>The Philosopher who is acquainted with these facts concerning the + cuckoo, would seem to have very little <i>reason</i> himself, if he could + imagine this neglect of her young to be a necessary <i>instinct</i>!</p> + + <p><a name="sect_XVI_14">XIV</a>. The deep recesses of the ocean are + inaccessible to mankind, which prevents us from having much knowledge of + the arts and government of its inhabitants.</p> + + <p><a name="sect_XVI_14_1">1</a>. One of the baits used by the fisherman + is an animal called an Old Soldier, his size and form are somewhat like + the craw-fish, with this difference, that his tail is covered with a + tough membrane instead of a shell; and to obviate this defect, he seeks + out the uninhabited shell of some dead fish, that is large enough to + receive his tail, and carries it about with him as part of his clothing + or armour.</p> + + <p><a name="sect_XVI_14_2">2</a>. On the coasts about Scarborough, where + the haddocks, cods, and dog-fish, are in great abundance, the fishermen + universally believe that the dog-fish make a line, or semicircle, to + encompass a shoal of haddocks and cod, confining them within certain + limits near the shore, and eating them as occasion requires. For the + haddocks and cod are always found near the shore without any dog-fish + among them, and the dog-fish further off without any haddocks or cod; and + yet the former are known to prey upon the latter, and in some years + devour such immense quantities as to render this fishery more expensive + than profitable.</p> + + <p><a name="sect_XVI_14_3">3</a>. The remora, when he wishes to remove + his situation, as he is a very slow swimmer, is content to take an + outside place on whatever conveyance is going his way; nor can the + cunning animal be tempted to quit his hold of a ship when she is sailing, + not even for the lucre of a piece of pork, lest it should endanger the + loss of his passage: at other times he is easily caught with the + hook.</p> + + <p><a name="sect_XVI_14_4">4</a>. The crab-fish, like many other + testaceous animals, annually changes its shell; it is then in a soft + state, covered only with a mucous membrane, and conceals itself in holes + in the sand or under weeds; at this place a hard shelled crab always + stands centinel, to prevent the sea insects from injuring the other in + its defenceless state; and the fishermen from his appearance know where + to find the soft ones, which they use for baits in catching other + fish.</p> + + <p>And though the hard shelled crab, when he is on this duty, advances + boldly to meet the foe, and will with difficulty quit the field; yet at + other times he shews great timidity, and has a wonderful speed in + attempting his escape; and, if often interrupted, will pretend death like + the spider, and watch an opportunity to sink himself into the sand, + keeping only his eyes above. My ingenious friend Mr. Burdett, who + favoured me with these accounts at the time he was surveying the coasts, + thinks the commerce between the sexes takes place at this time, and + inspires the courage of the creature.</p> + + <p><a name="sect_XVI_14_5">5</a>. The shoals of herrings, cods, haddocks, + and other fish, which approach our shores at certain seasons, and quit + them at other seasons without leaving one behind; and the salmon, that + periodically frequent our rivers, evince, that there are vagrant tribes + of fish, that perform as regular migrations as the birds of passage + already mentioned.</p> + + <p><a name="sect_XVI_14_6">6</a>. There is a cataract on the river Liffey + in Ireland about nineteen feet high: here in the salmon season many of + the inhabitants amuse themselves in observing these fish leap up the + torrent. They dart themselves quite out of the water as they ascend, and + frequently fall back many times before they surmount it, and baskets made + of twigs are placed near the edge of the stream to catch them in their + fall.</p> + + <p>I have observed, as I have sat by a spout of water, which descends + from a stone trough about two feet into a stream below, at particular + seasons of the year, a great number of little fish called minums, or + pinks, throw themselves about twenty times their own length out of the + water, expecting to get into the trough above.</p> + + <p>This evinces that the storgee, or attention of the dam to provide for + the offspring, is strongly exerted amongst the nations of fish, where it + would seem to be the most neglected; as these salmon cannot be supposed + to attempt so difficult and dangerous a task without being conscious of + the purpose or end of their endeavours.</p> + + <p>It is further remarkable, that most of the old salmon return to the + sea before it is proper for the young shoals to attend them, yet that a + few old ones continue in the rivers so late, that they become perfectly + emaciated by the inconvenience of their situation, and this apparently to + guide or to protect the unexperienced brood.</p> + + <p>Of the smaller water animals we have still less knowledge, who + nevertheless probably possess many superior arts; some of these are + mentioned in Botanic Garden, P. I. Add. Note XXVII. and XXVIII. The + nympha of the water-moths of our rivers, which cover themselves with + cases of straw, gravel, and shell, contrive to make their habitations, + nearly in equilibrium with the water; when too heavy, they add a bit of + wood or straw; when too light, a bit of gravel. Edinb. Trans.</p> + + <p>All these circumstances bear a near resemblance to the deliberate + actions of human reason.</p> + + <p><a name="sect_XVI_15">XV</a>. We have a very imperfect acquaintance + with the various tribes of insects: their occupations, manner of life, + and even the number of their senses, differ from our own, and from each + other; but there is reason to imagine, that those which possess the sense + of touch in the most exquisite degree, and whole occupations require the + most constant exertion of their powers, are induced with a greater + proportion or knowledge and ingenuity.</p> + + <p>The spiders of this country manufacture nets of various forms, adapted + to various situations, to arrest the flies that are their food; and some + of them have a house or lodging-place in the middle of the net, well + contrived for warmth, security, or concealment. There is a large spider + in South America, who constructs nets of so strong a texture as to + entangle small birds, particularly the humming bird. And in Jamaica there + is another spider, who digs a hole in the earth obliquely downwards, + about three inches in length, and one inch in diameter, this cavity she + lines with a tough thick web, which when taken out resembles a leathern + purse: but what is most curious, this house has a door with hinges, like + the operculum of some sea shells; and herself and family, who tenant this + nest, open and shut the door, whenever they pass or repass. This history + was told me, and the nest with its operculum shewn me by the late Dr. + Butt of Bath, who was some years physician in Jamaica.</p> + + <p>The production of these nets is indeed a part of the nature or + conformation of the animal, and their natural use is to supply the place + of wings, when she wishes to remove to another situation. But when she + employs them to entangle her prey, there are marks of evident design, for + she adapts the form of each net to its situation, and strengthens those + lines, that require it, by joining others to the middle of them, and + attaching those others to distant objects, with the same individual art, + that is used by mankind in supporting the masts and extending the sails + of ships. This work is executed with more mathematical exactness and + ingenuity by the field spiders, than by those in our houses, as their + constructions are more subjected to the injuries of dews and + tempests.</p> + + <p>Besides the ingenuity shewn by these little creatures in taking their + prey, the circumstance of their counterfeiting death, when they are put + into terror, is truly wonderful; and as soon as the object of terror is + removed, they recover and run away. Some beetles are also said to possess + this piece of hypocrisy.</p> + + <p>The curious webs, or chords, constructed by some young caterpillars to + defend themselves from cold, or from insects of prey; and by silk-worms + and some other caterpillars, when they transmigrate into aureliæ or + larvæ, have deservedly excited the admiration of the inquisitive. But our + ignorance of their manner of life, and even of the number of their + senses, totally precludes us from understanding the means by which they + acquire this knowledge.</p> + + <p>The care of the salmon in choosing a proper situation for her spawn, + the structure of the nests of birds, their patient incubation, and the + art of the cuckoo in depositing her egg in her neighbour's nursery, are + instances of great sagacity in those creatures: and yet they are much + inferior to the arts exerted by many of the insect tribes on similar + occasions. The hairy excrescences on briars, the oak apples, the blasted + leaves of trees, and the lumps on the backs of cows, are situations that + are rather produced than chosen by the mother insect for the convenience + of her offspring. The cells of bees, wasps, spiders, and of the various + coralline insects, equally astonish us, whether we attend to the + materials or to the architecture.</p> + + <p>But the conduct of the ant, and of some species of the ichneumon fly + in the incubation of their eggs, is equal to any exertion of human + science. The ants many times in a day move their eggs nearer the surface + of their habitation, or deeper below it, as the heat of the weather + varies; and in colder days lie upon them in heaps for the purpose of + incubation: if their mansion is too dry, they carry them to places where + there is moisture, and you may distinctly see the little worms move and + suck up the water. When too much moisture approaches their nest, they + convey their eggs deeper in the earth, or to some other place of safety. + (Swammerd. Epil. ad Hist. Insects, p. 153. Phil. Trans. No. 23. Lowthrop. + V. 2. p. 7.)</p> + + <p>There is one species of ichneumon-fly, that digs a hole in the earth, + and carrying into it two or three living caterpillars, deposits her eggs, + and nicely closing up the nest leaves them there; partly doubtless to + assist the incubation, and partly to supply food to her future young, + (Derham. B. 4, c. 13. Aristotle Hist. Animal, L. 5. c. 20.)</p> + + <p>A friend of mine put about fifty large caterpillars collected from + cabbages on some bran and a few leaves into a box, and covered it with + gauze to prevent their escape. After a few days we saw, from more than + three fourths of them, about eight or ten little caterpillars of the + ichneumon-fly come out of their backs, and spin each a small cocoon of + silk, and in a few days the large caterpillars died. This small fly it + seems lays its egg in the back of the cabbage caterpillar, which when + hatched preys upon the material, which is produced there for the purpose + of making silk for the future nest of the cabbage caterpillar; of which + being deprived, the creature wanders about till it dies, and thus our + gardens are preserved by the ingenuity of this cruel fly. This curious + property of producing a silk thread, which is common to some sea animals, + see Botanic Garden, Part I. Note XXVII. and is designed for the purpose + of their transformation as in the silk-worm, is used for conveying + themselves from higher branches to lower ones of trees by some + caterpillars, and to make themselves temporary nests or tents, and by the + spider for entangling his prey. Nor is it strange that so much knowledge + should be acquired by such small animals; since there is reason to + imagine, that these insects have the sense of touch, either in their + proboscis, or their antennæ, to a great degree of perfection; and thence + may possess, as far as their sphere extends, as accurate knowledge, and + as subtle invention, as the discoverers of human arts.</p> + + <p><a name="sect_XVI_16">XVI</a>. <a name="sect_XVI_16_1">1</a>. If we + were better acquainted with the histories of those insects that are + formed into societies, as the bees, wasps, and ants, I make no doubt but + we should find, that their arts and improvements are not so similar and + uniform as they now appear to us, but that they arose in the same manner + from experience and tradition, as the arts of our own species; though + their reasoning is from fewer ideas, is busied about fewer objects, and + is exerted with less energy.</p> + + <p>There are some kinds of insects that migrate like the birds before + mentioned. The locust of warmer climates has sometimes come over to + England; it is shaped like a grasshopper, with very large wings, and a + body above an inch in length. It is mentioned as coming into Egypt with + an east wind, "The lord brought an east wind upon the land all that day + and night, and in the morning the east wind brought the locusts, and + covered the face of the earth, so that the land was dark," Exod. x. 13. + The migrations of these insects are mentioned in another part of the + scripture, "The locusts have no king, yet go they forth all of them in + bands," Prov. xxx. 27.</p> + + <p>The accurate Mr. Adanson, near the river Gambia in Africa, was witness + to the migration of these insects. "About eight in the morning, in the + month of February, there suddenly arose over our heads a thick cloud, + which darkened the air, and deprived us of the rays of the sun. We found + it was a cloud of locusts raised about twenty or thirty fathoms from the + ground, and covering an extent of several leagues; at length a shower of + these insects descended, and after devouring every green herb, while they + rested, again resumed their flight. This cloud was brought by a strong + east-wind, and was all the morning in passing over the adjacent country." + (Voyage to Senegal, 158.)</p> + + <p>In this country the gnats are sometimes seen to migrate in clouds, + like the musketoes of warmer climates, and our swarms of bees frequently + travel many miles, and are said in North America always to fly towards + the south. The prophet Isaiah has a beautiful allusion to these + migrations, "The Lord shall call the fly from the rivers of Egypt, and + shall hiss for the bee that is in the land of Assyria," Isa. vii. 18. + which has been lately explained by Mr. Bruce, in his travels to discover + the source of the Nile.</p> + + <p><a name="sect_XVI_16_2">2</a>. I am well informed that the bees that + were carried into Barbadoes, and other western islands, ceased to lay up + any honey after the first year, as they found it not useful to them: and + are now become very troublesome to the inhabitants of those islands by + infesting their sugar houses; but those in Jamaica continue to make + honey, as the cold north winds, or rainy seasons of that island, confine + them at home for several weeks together. And the bees of Senegal, which + differ from those of Europe only in size, make their honey not only + superior to ours in delicacy of flavour, but it has this singularity, + that it never concretes, but remains liquid as syrup, (Adanson). From + some observations of Mr. Wildman, and of other people of veracity, it + appears, that during the severe part of the winter season for weeks + together the bees are quite benumbed and torpid from the cold, and do not + consume any of their provision. This state of sleep, like that of + swallows and bats, seems to be the natural resource of those creatures in + cold climates, and the making of honey to be an artificial + improvement.</p> + + <p>As the death of our hives of bees appears to be owning to their being + kept so warm, as to require food when their stock is exhausted; a very + observing gentleman at my request put two hives for many weeks into a dry + cellar, and observed, during all that time, they did not consume any of + their provision, for their weight did not decrease as it had done when + they were kept in the open air. The same observation is made in the + Annual Register for 1768, p. 113. And the Rev. Mr. White, in his Method + of preserving Bees, adds, that those on the north side of his house + consumed less honey in the winter than those on the south side.</p> + + <p>There is another observation on bees well ascertained, that they at + various times, when the season begins to be cold, by a general motion of + their legs as they hang in clusters produce a degree of warmth, which is + easily perceptible by the hand. Hence by this ingenious exertion, they + for a long time prevent the torpid state they would naturally fall + into.</p> + + <p>According to the late observations of Mr. Hunter, it appears that the + bee's-wax is not made from the dust of the anthers of flowers, which they + bring home on their thighs, but that this makes what is termed bee-bread, + and is used for the purpose of feeding the bee-maggots; in the same + manner butterflies live on honey, but the previous caterpillar lives on + vegetable leaves, while the maggots of large flies require flesh for + their food, and those of the ichneumon fly require insects for their + food. What induces the bee who lives on honey to lay up vegetable powder + for its young? What induces the butterfly to lay its eggs on leaves, when + itself feeds on honey? What induces the other flies to seek a food for + their progeny different from what they consume themselves? If these are + not deductions from their own previous experience or observation, all the + actions of mankind must be resolved into instinct.</p> + + <p><a name="sect_XVI_16_3">3</a>. The dormouse consumes but little of its + food during the rigour of the season, for they roll themselves up, or + sleep, or lie torpid the greatest part of the time; but on warm sunny + days experience a short revival, and take a little food, and then relapse + into their former state." (Pennant Zoolog. p. 67.) Other animals, that + sleep in winter without laying up any provender, are observed to go into + their winter beds fat and strong, but return to day-light in the spring + season very lean and feeble. The common flies sleep during the winter + without any provision for their nourishment, and are daily revived by the + warmth of the sun, or of our fires. These whenever they see light + endeavour to approach it, having observed, that by its greater vicinity + they get free from the degree of torpor, that the cold produces; and are + hence induced perpetually to burn themselves in our candles: deceived, + like mankind, by the misapplication of their knowledge. Whilst many of + the subterraneous insects, as the common worms, seem to retreat so deep + into the earth as not to be enlivened or awakened by the difference of + our winter days; and stop up their holes with leaves or straws, to + prevent the frosts from injuring them, or the centipes from devouring + them. The habits of peace, or the stratagems of war, of these + subterranean nations are covered from our view; but a friend of mine + prevailed on a distressed worm to enter the hole of another worm on a + bowling-green, and he presently returned much wounded about his head. And + I once saw a worm rise hastily out of the earth into the sunshine, and + observed a centipes hanging at its tail: the centipes nimbly quitted the + tail, and seizing the worm about its middle cut it in half with its + forceps, and preyed upon one part, while the other escaped. Which evinces + they have design in stopping the mouths of their habitations.</p> + + <p><a name="sect_XVI_16_4">4</a>. The wasp of this country fixes his + habitation under ground, that he may not be affected with the various + changes of our climate; but in Jamaica he hangs it on the bough of a + tree, where the seasons are less severe. He weaves a very curious paper + of vegetable fibres to cover his nest, which is constructed on the same + principle with that of the bee, but with a different material; but as his + prey consists of flesh, fruits, and insects, which are perishable + commodities, he can lay up no provender for the winter.</p> + + <p>M. de la Loubiere, in his relation of Siam, says, "That in a part of + that kingdom, which lies open to great inundations, all the ants make + their settlements upon trees; no ants' nests are to be seen any where + else." Whereas in our country the ground is their only situation. From + the scriptual account of these insects, one might be led to suspect, that + in some climates they lay up a provision for the winter. Origen affirms + the same, (Cont. Cels. L. 4.) But it is generally believed that in this + country they do not, (Prov. vi. 6. xxx. 25.) The white ants of the coast + of Africa make themselves pyramids eight or ten feet high, on a base of + about the same width, with a smooth surface of rich clay, excessively + hard and well built, which appear at a distance like an assemblage of the + huts of the negroes, (Adanson). The history of these has been lately well + described in the Philosoph. Transactions, under the name of termes, or + termites. These differ very much from the nest of our large ant; but the + real history of this creature, as well as of the wasp, is yet very + imperfectly known.</p> + + <p>Wasps are said to catch large spiders, and to cut off their legs, and + carry their mutilated bodies to their young, Dict. Raison. Tom. I. p. + 152.</p> + + <p>One circumstance I shall relate which fell under my own eye, and + shewed the power or reason in a wasp, as it is exercised among men. A + wasp, on a gravel walk, had caught a fly nearly as large as himself; + kneeling on the ground I observed him separate the tail and the head from + the body part, to which the wings were attached. He then took the body + part in his paws, and rose about two feet from the ground with it; but a + gentle breeze wafting the wings of the fly turned him round in the air, + and he settled again with his prey upon the gravel. I then distinctly + observed him cut off with his mouth, first one of the wings, and then the + other, after which he flew away with it unmolested by the wind.</p> + + <p>Go, thou sluggard, learn arts and industry from the bee, and from the + ant!</p> + + <p>Go, proud reasoner, and call the worm thy sister!</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XVI_17">XVII</a>. <i>Conclusion.</i></p> + + <p>It was before observed how much the superior accuracy of our sense of + touch contributes to increase our knowledge; but it is the greater energy + and activity of the power of volition (as explained in the former + Sections of this work) that marks mankind, and has given him the empire + of the world.</p> + + <p>There is a criterion by which we may distinguish our voluntary acts or + thoughts from those that are excited by our sensations: "The former are + always employed about the <i>means</i> to acquire pleasureable objects, + or to avoid painful ones: while the latter are employed about the + <i>possession</i> of those that are already in our power."</p> + + <p>If we turn our eyes upon the fabric of our fellow animals, we find + they are supported with bones, covered with skins, moved by muscles; that + they possess the same senses, acknowledge the same appetites, and are + nourished by the same aliment with ourselves; and we should hence + conclude from the strongest analogy, that their internal faculties were + also in some measure similar to our own.</p> + + <p>Mr. Locke indeed published an opinion, that other animals possessed no + abstract or general ideas, and thought this circumstance was the barrier + between the brute and the human world. But these abstracted ideas have + been since demonstrated by Bishop Berkley, and allowed by Mr. Hume, to + have no existence in nature, not even in the mind of their inventor, and + we are hence necessitated to look for some other mark of distinction.</p> + + <p>The ideas and actions of brutes, like those of children, are almost + perpetually produced by their present pleasures, or their present pains; + and, except in the few instances that have been mentioned in this + Section, they seldom busy themselves about the <i>means</i> of procuring + future bliss, or of avoiding future misery.</p> + + <p>Whilst the acquiring of languages, the making of tools, and the + labouring for money; which are all only the <i>means</i> of procuring + pleasure; and the praying to the Deity, as another <i>means</i> to + procure happiness, are characteristic of human nature.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XVII">XVII</a>.</h3> + +<p class="center" style="margin-top: 2em;">THE CATENATION OF MOTIONS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XVII_1">I</a>. <a href="#sect_XVII_1_1">1</a>. + <i>Catenations of animal motion.</i> <a href="#sect_XVII_1_2">2</a>. + <i>Are produced by irritations, by sensations, by volitions.</i> <a + href="#sect_XVII_1_3">3</a>. <i>They continue some time after they have + been excited. Cause of catenation.</i> <a href="#sect_XVII_1_4">4</a>. + <i>We can then exert our attention on other objects.</i> <a + href="#sect_XVII_1_5">5</a>. <i>Many catenations of motions go on + together.</i> <a href="#sect_XVII_1_6">6</a>. <i>Some links of the + catenations of motions may be left out without disuniting the chain.</i> + <a href="#sect_XVII_1_7">7</a>. <i>Interrupted circles of motion continue + confusedly till they come to the part of the circle, where they were + disturbed.</i> <a href="#sect_XVII_1_8">8</a>. <i>Weaker catenations are + dissevered by stronger.</i> <a href="#sect_XVII_1_9">9</a>. <i>Then new + catenations take place.</i> <a href="#sect_XVII_1_10">10</a>. <i>Much + effort prevents their reuniting. Impediment of speech.</i> <a + href="#sect_XVII_1_11">11</a>. <i>Trains more easily dissevered than + circles.</i> <a href="#sect_XVII_1_12">12</a>. <i>Sleep destroys volition + and external stimulus.</i> <a href="#sect_XVII_2">II</a>. <i>Instances of + various catenations in a young lady playing on the harpsichord.</i> <a + href="#sect_XVII_3">III</a>. <a href="#sect_XVII_3_1">1</a>. <i>What + catenations are the strongest.</i> <a href="#sect_XVII_3_2">2</a>. + <i>Irritations joined with associations from strongest connexions. Vital + motions.</i> <a href="#sect_XVII_3_3">3</a>. <i>New links with increased + force, cold fits of fever produced.</i> <a href="#sect_XVII_3_4">4</a>. + <i>New links with decreased force. Cold bath.</i> <a + href="#sect_XVII_3_5">5</a>. <i>Irritation joined with sensation. + Inflammatory fever. Why children cannot tickle themselves. <a + href="#sect_XVII_3_6">6</a>. Volition joined with sensation. Irritative + ideas of sound become sensible.</i> <a href="#sect_XVII_3_7">7</a>. + <i>Ideas of imagination, dissevered by irritations, by volition, + production of surprise.</i></p> + +</blockquote> + + <p><a name="sect_XVII_1">I</a>. <a name="sect_XVII_1_1">1</a>. To + investigate with precision the catenations of animal motions, it would be + well to attend to the manner of their production; but we cannot begin + this disquisition early enough for this purpose, as the catenations of + motion seem to begin with life, and are only extinguishable with it; We + have spoken of the power of irritation, of sensation, of volition, and of + association, as preceding the fibrous motions; we now step forwards, and + consider, that conversely they are in their turn preceded by those + motions; and that all the successive trains or circles of our actions are + composed of this twofold concatenation. Those we shall call trains of + action, which continue to proceed without any stated repetitions; and + those circles of action, when the parts of them return at certain + periods, though the trains, of which they consist, are not exactly + similar. The reading an epic poem is a train of actions; the reading a + song with a chorus at equal distances in the measure constitutes so many + circles of action.</p> + + <p><a name="sect_XVII_1_2">2</a>. Some catenations of animal motion are + produced by reiterated successive irritations, as when we learn to repeat + the alphabet in its order by frequently reading the letters of it. Thus + the vermicular motions of the bowels were originally produced by the + successive irritations of the passing aliment; and the succession of + actions of the auricles and ventricles of the heart was originally formed + by successive stimulus of the blood, these afterwards become part of the + diurnal circles of animal actions, as appears by the periodical returns + of hunger, and the quickened pulse of weak people in the evening.</p> + + <p>Other catenations of animal motion are gradually acquired by + successive agreeable sensations, as in learning a favourite song or + dance; others by disagreeable sensations, as in coughing or nictitation; + these become associated by frequent repetition, and afterwards compose + parts of greater circles of action like those above mentioned.</p> + + <p>Other catenations of motions are gradually acquired by frequent + voluntary repetitions; as when we deliberately learn to march, read, + fence, or any mechanic art, the motions of many of our muscles become + gradually linked together in trains, tribes, or circles of action. Thus + when any one at first begins to use the tools in turning wood or metals + in a lathe, he wills the motions of his hand or fingers, till at length + these actions become so connected with the effect, that he seems only to + will the point of the chisel. These are caused by volition, connected by + association like those above described, and afterwards become parts of + our diurnal trains or circles of action.</p> + + <p><a name="sect_XVII_1_3">3</a>. All these catenations of animal + motions, are liable to proceed some time after they are excited, unless + they are disturbed or impeded by other irritations, sensations, or + volitions; and in many instances in spite of our endeavours to stop them; + and this property of animal motions is probably the cause of their + catenation. Thus when a child revolves some minute on one foot, the + spectra of the ambient objects appear to circulate round him some time + after he falls upon the ground. Thus the palpitation of the heart + continues some time after the object of fear, which occasioned it, is + removed. The blush of shame, which is an excess of sensation, and the + glow of anger, which is an excess of volition, continue some time, though + the affected person finds, that those emotions were caused by mistaken + facts, and endeavours to extinguish their appearance. See Sect. <a + href="#sect_XII_1_5">XII. 1. 5</a>.</p> + + <p><a name="sect_XVII_1_4">4</a>. When a circle of motions becomes + connected, by frequent repetitions as above, we can exert our attention + strongly on other objects, and the concatenated circle of motions will + nevertheless proceed in due order; as whilst you are thinking on this + subject, you use variety of muscles in walking about your parlour, or in + sitting at your writing-table.</p> + + <p><a name="sect_XVII_1_5">5</a>. Innumerable catenations of motions may + proceed at the same time, without incommoding each other. Of these are + the motions of the heart and arteries; those of digestion and glandular + secretion; of the ideas, or sensual motions; those of progression, and of + speaking; the great annual circle of actions so apparent in birds in + their times of breeding and moulting; the monthly circles of many female + animals; and the diurnal circles of sleeping and waking, of fulness and + inanition.</p> + + <p><a name="sect_XVII_1_6">6</a>. Some links of successive trains or of + synchronous tribes of action may be left out without disjoining the + whole. Such are our usual trains of recollection; after having travelled + through an entertaining country, and viewed many delightful lawns, + rolling rivers, and echoing rocks; in the recollection of our journey we + leave out the many districts, that we crossed, which were marked with no + peculiar pleasure. Such also are our complex ideas, they are catenated + tribes of ideas, which do not perfectly resemble their correspondent + perceptions, because some of the parts are omitted.</p> + + <p><a name="sect_XVII_1_7">7</a>. If an interrupted circle of actions is + not entirely dissevered, it will continue to proceed confusedly, till it + comes to the part of the circle, where it was interrupted.</p> + + <p>The vital motions in a fever from drunkenness, and in other periodical + diseases, are instances of this circumstance. The accidental inebriate + does not recover himself perfectly till about the same hour on the + succeeding day. The accustomed drunkard is disordered, if he has not his + usual potation of fermented liquor. So if a considerable part of a + connected tribe of action be disturbed, that whole tribe goes on with + confusion, till the part of the tribe affected regains its accustomed + catenations. So vertigo produces vomiting, and a great secretion of bile, + as in sea-sickness, all these being parts of the tribe of irritative + catenations.</p> + + <p><a name="sect_XVII_1_8">8</a>. Weaker catenated trains may be + dissevered by the sudden exertion of the stronger. When a child first + attempts to walk across a room, call to him, and he instantly falls upon + the ground. So while I am thinking over the virtues of my friends, if the + tea-kettle spurt out some hot water on my stocking; the sudden pain + breaks the weaker chain of ideas, and introduces a new group of figures + of its own. This circumstance is extended to some unnatural trains of + action, which have not been confirmed by long habit; as the hiccough, or + an ague-fit, which are frequently curable by surprise. A young lady about + eleven years old had for five days had a contraction of one muscle in her + fore arm, and another in her arm, which occurred four or five times every + minute; the muscles were seen to leap, but without bending the arm. To + counteract this new morbid habit, an issue was placed over the convulsed + muscle of her arm, and an adhesive plaster wrapped tight like a bandage + over the whole fore arm, by which the new motions were immediately + destroyed, but the means were continued some weeks to prevent a + return.</p> + + <p><a name="sect_XVII_1_9">9</a>. If any circle of actions is dissevered, + either by omission of some of the links, as in sleep, or by insertion of + other links, as in surprise, new catenations take place in a greater or + less degree. The last link of the broken chain of actions becomes + connected with the new motion which has broken it, or with that which was + nearest the link omitted; and these new catenations proceed instead of + the old ones. Hence the periodic returns of ague-fits, and the chimeras + of our dreams.</p> + + <p><a name="sect_XVII_1_10">10</a>. If a train of actions is dissevered, + much effort of volition or sensation will prevent its being restored. + Thus in the common impediment of speech, when the association of the + motions of the muscles of enunciation with the idea of the word to be + spoken is disordered, the great voluntary efforts, which distort the + countenance, prevent the rejoining of the broken associations. See No. <a + href="#sect_XVII_2_10">II. 10</a>. of this Section. It is thus likewise + observable in some inflammations of the bowels, the too strong efforts + made by the muscles to carry forwards the offending material fixes it + more firmly in its place, and prevents the cure. So in endeavouring to + recal to our memory some particular word of a sentence, if we exert + ourselves too strongly about it, we are less likely to regain it.</p> + + <p><a name="sect_XVII_1_11">11</a>. Catenated trains or tribes of action + are easier dissevered than catenated circles of action. Hence in + epileptic fits the synchronous connected tribes of action, which keep the + body erect, are dissevered, but the circle of vital motions continues + undisturbed.</p> + + <p><a name="sect_XVII_1_12">12</a>. Sleep destroys the power of volition, + and precludes the stimuli of external objects, and thence dissevers the + trains, of which these are a part; which confirms the other catenations, + as those of the vital motions, secretions, and absorptions; and produces + the new trains of ideas, which constitute our dreams.</p> + + <p><a name="sect_XVII_2">II</a>. <a name="sect_XVII_2_1">1</a>. All the + preceding circumstances of the catenations of animal motions will be more + clearly understood by the following example of a person learning music; + and when we recollect the variety of mechanic arts, which are performed + by associated trains of muscular actions catenated with the effects they + produce, as in knitting, netting, weaving; and the greater variety of + associated trains of ideas caused or catenated by volitions or + sensations, as in our hourly modes of reasoning, or imagining, or + recollecting, we shall gain some idea of the innumerable catenated trains + and circles of action, which form the tenor of our lives, and which + began, and will only cease entirely with them.</p> + + <p><a name="sect_XVII_2_2">2</a>. When a young lady begins to learn + music, she voluntarily applies herself to the characters of her + music-book, and by many repetitions endeavours to catenate them with the + proportions of sound, of which they are symbols. The ideas excited by the + musical characters are slowly connected with the keys of the harpsichord, + and much effort is necessary to produce every note with the proper + finger, and in its due place and time; till at length a train of + voluntary exertions becomes catenated with certain irritations. As the + various notes by frequent repetitions become connected in the order, in + which they are produced, a new catenation of sensitive exertions becomes + mixed with the voluntary ones above described; and not only the musical + symbols of crotchets and quavers, but the auditory notes and tones at the + same time, become so many successive or synchronous links in this circle + of catenated actions.</p> + + <p>At length the motions of her fingers become catenated with the musical + characters; and these no sooner strike the eye, than the finger presses + down the key without any voluntary attention between them; the activity + of the hand being connected with the irritation of the figure or place of + the musical symbol on the retina; till at length by frequent repetitions + of the same tune the movements of her fingers in playing, and the muscles + of the larynx in singing, become associated with each other, and form + part of those intricate trains and circles of catenated motions, + according with the second article of the preceding propositions in No. <a + href="#sect_XVII_1">1</a>. of this Section.</p> + + <p><a name="sect_XVII_2_3">3</a>. Besides the facility, which by habit + attends the execution of this musical performance, a curious circumstance + occurs, which is, that when our young musician has began a tune, she + finds herself inclined to continue it; and that even when she is + carelessly singing alone without attending to her own song; according + with the third preceding article.</p> + + <p><a name="sect_XVII_2_4">4</a>. At the same time that our young + performer continues to play with great exactness this accustomed tune, + she can bend her mind, and that intensely, on some other object, + according with the fourth article of the preceding proportions.</p> + + <p>The manuscript copy of this work was lent to many of my friends at + different times for the purpose of gaining their opinions and criticisms + on many parts of it, and I found the following anecdote written with a + pencil opposite to this page, but am not certain by whom. "I remember + seeing the pretty young actress, who succeeded Mrs. Arne in the + performance of the celebrated Padlock, rehearse the musical parts at her + harpsichord under the eye of her master with great taste and accuracy; + though I observed her countenance full of emotion, which I could not + account for; at last she suddenly burst into tears; for she had all this + time been eyeing a beloved canary bird, suffering great agonies, which at + that instant fell dead from its perch."</p> + + <p><a name="sect_XVII_2_5">5</a>. At the same time many other catenated + circles of action are going on in the person of our fair musician, as + well as the motions of her fingers, such as the vital motions, + respiration, the movements of her eyes and eyelids, and of the intricate + muscles of vocality, according with the fifth preceding article.</p> + + <p><a name="sect_XVII_2_6">6</a>. If by any strong impression on the mind + of our fair musician she should be interrupted for a very inconsiderable + time, she can still continue her performance, according to the sixth + article.</p> + + <p><a name="sect_XVII_2_7">7</a>. If however this interruption be + greater, though the chain of actions be not dissevered, it proceeds + confusedly, and our young performer continues indeed to play, but in a + hurry without accuracy and elegance, till she begins the tune again, + according to the seventh of the preceding articles.</p> + + <p><a name="sect_XVII_2_8">8</a>. But if this interruption be still + greater, the circle of actions becomes entirely dissevered, and she finds + herself immediately under the necessity to begin over again to recover + the lost catenation, according to the eighth preceding article.</p> + + <p><a name="sect_XVII_2_9">9</a>. Or in trying to recover it she will + sing some dissonant notes, or strike some improper keys, according to the + ninth preceding article.</p> + + <p><a name="sect_XVII_2_10">10</a>. A very remarkable thing attends this + breach of catenation, if the performer has forgotten some word of her + song, the more energy of mind she uses about it, the more distant is she + from regaining it; and artfully employs her mind in part on some other + object, or endeavours to dull its perceptions, continuing to repeat, as + it were inconsciously, the former part of the song, that she remembers, + in hopes to regain the lost connexion.</p> + + <p>For if the activity of the mind itself be more energetic, or takes its + attention more, than the connecting word, which is wanted; it will not + perceive the slighter link of this lost word; as who listens to a feeble + sound, must be very silent and motionless; so that in this case the very + vigour of the mind itself seems to prevent it from regaining the lost + catenation, as well as the too great exertion in endeavouring to regain + it, according to the tenth preceding article.</p> + + <p>We frequently experience, when we are doubtful about the spelling of a + word, that the greater voluntary exertion we use, that is the more + intensely we think about it, the further are we from regaining the lost + association between the letters of it, but which readily recurs when we + have become careless about it. In the same manner, after having for an + hour laboured to recollect the name of some absent person, it shall seem, + particularly after sleep, to come into the mind as it were spontaneously; + that is the word we are in search of, was joined to the preceding one by + association; this association being dissevered, we endeavour to recover + it by volition; this very action of the mind strikes our attention more, + than the faint link of association, and we find it impossible by this + means to retrieve the lost word. After sleep, when volition is entirely + suspended, the mind becomes capable of perceiving the fainter link of + association, and the word is regained.</p> + + <p>On this circumstance depends the impediment of speech before + mentioned; the first syllable of a word is causable by volition, but the + remainder of it is in common conversation introduced by its associations + with this first syllable acquired by long habit. Hence when the mind of + the stammerer is vehemently employed on some idea of ambition of shining, + or fear of not succeeding, the associations of the motions of the muscles + of articulation with each other become dissevered by this greater + exertion, and he endeavours in vain by voluntary efforts to rejoin the + broken association. For this purpose he continues to repeat the first + syllable, which is causable by volition, and strives in vain, by various + distortions of countenance, to produce the next links, which are subject + to association. See Class IV. 3. 1. 1.</p> + + <p><a name="sect_XVII_2_11">11</a>. After our accomplished musician has + acquired great variety of tunes and songs, so that some of them begin to + cease to be easily recollected, she finds progressive trains of musical + notes more frequently forgotten, than those which are composed of + reiterated circles, according with the eleventh preceding article.</p> + + <p><a name="sect_XVII_2_12">12</a>. To finish our example with the + preceding articles we must at length suppose, that our fair performer + falls asleep over her harpsichord; and thus by the suspension of + volition, and the exclusion of external stimuli, she dissevers the trains + and circles of her musical exertions.</p> + + <p><a name="sect_XVII_3">III</a>. <a name="sect_XVII_3_1">1</a>. Many of + these circumstances of catenations of motions receive an easy explanation + from the four following consequences to the seventh law of animal + causation in Sect. <a href="#sect_IV">IV</a>. These are, first, that + those successions or combinations of animal motions, whether they were + united by causation, association, or catenation, which have been most + frequently repeated, acquire the strongest connection. Secondly, that of + these, those, which have been less frequently mixed with other trains or + tribes of motion, have the strongest connection. Thirdly, that of these, + those, which were first formed, have the strongest connection. Fourthly, + that if an animal motion be excited by more than one causation, + association, or catenation, at the same time, it will be performed with + greater energy.</p> + + <p><a name="sect_XVII_3_2">2</a>. Hence also we understand, why the + catenations of irritative motions are more strongly connected than those + of the other classes, where the quantity of unmixed repetition has been + equal; because they were first formed. Such are those of the secerning + and absorbent systems of vessels, where the action of the gland produces + a fluid, which stimulates the mouths of its correspondent absorbents. The + associated motions seem to be the next most strongly united, from their + frequent repetition; and where both these circumstances unite, as in the + vital motions, their catenations are indissoluble but by the destruction + of the animal.</p> + + <p><a name="sect_XVII_3_3">3</a>. Where a new link has been introduced + into a circle of actions by some accidental defect of stimulus; if that + defect of stimulus be repeated at the same part of the circle a second or + a third time, the defective motions thus produced, both by the repeated + defect of stimulus and by their catenation with the parts of the circle + of actions, will be performed with less and less energy. Thus if any + person is exposed to cold at a certain hour to-day, so long as to render + some part of the system for a time torpid; and is again exposed to it at + the same hour to-morrow, and the next day; he will be more and more + affected by it, till at length a cold fit of fever is completely formed, + as happens at the beginning of many of those fevers, which are called + nervous or low fevers. Where the patient has slight periodical shiverings + and paleness for many days before the febrile paroxysm is completely + formed.</p> + + <p><a name="sect_XVII_3_4">4</a>. On the contrary, if the exposure to + cold be for so short a time, as not to induce any considerable degree of + torpor or quiescence, and is repeated daily as above mentioned, it loses + its effect more and more at every repetition, till the constitution can + bear it without inconvenience, or indeed without being conscious of it. + As in walking into the cold air in frosty weather. The same rule is + applicable to increased stimulus, as of heat, or of vinous spirit, within + certain limits, as is applied in the two last paragraphs to Deficient + Stimulus; as is further explained in Sect. <a + href="#sect_XXXVI">XXXVI</a>. on the Periods of Diseases.</p> + + <p><a name="sect_XVII_3_5">5</a>. Where irritation coincides with + sensation to produce the same catenations of motion, as in inflammatory + fevers, they are excited with still greater energy than by the irritation + alone. So when children expect to be tickled in play, by a feather + lightly passed over the lips, or by gently vellicating the soles of their + feet, laughter is most vehemently excited; though they can stimulate + these parts with their own fingers unmoved. Here the pleasureable idea of + playfulness coincides with the vellication; and there is no voluntary + exertion used to diminish the sensation, as there would be, if a child + should endeavour to tickle himself. See Sect. <a + href="#sect_XXXIV_1_4">XXXIV. 1. 4</a>.</p> + + <p><a name="sect_XVII_3_6">6</a>. And lastly, the motions excited by the + junction of voluntary exertion with irritation are performed with more + energy, than those by irritation singly; as when we listen to small + noises, as to the ticking of a watch in the night, we perceive the most + weak sounds, that are at other times unheeded. So when we attend to the + irritative ideas of sound in our ears, which are generally not attended + to, we can hear them; and can see the spectra of objects, which remain in + the eye, whenever we please to exert our voluntary power in aid of those + weak actions of the retina, or of the auditory nerve.</p> + + <p><a name="sect_XVII_3_7">7</a>. The temporary catenations of ideas, + which are caused by the sensations of pleasure or pain, are easily + dissevered either by irritations, as when a sudden noise disturbs a + day-dream; or by the power of volition, as when we awake from sleep. + Hence in our waking hours, whenever an idea occurs, which is incongruous + to our former experience, we instantly dissever the train of imagination + by the power of volition, and compare the incongruous idea with our + previous knowledge of nature, and reject it. This operation of the mind + has not yet acquired a specific name, though it is exerted every minute + of our waking hours; unless it may be termed <font class="sc">INTUITIVE + ANALOGY</font>. It is an act of reasoning of which we are unconscious + except from its effects in preserving the congruity of our ideas, and + bears the same relation to the sensorial power of volition, that + irritative ideas, of which we are inconscious except by their effects, do + to the sensorial power of irritation; as the former is produced by + volition without our attention to it, and the latter by irritation + without our attention to them.</p> + + <p>If on the other hand a train of imagination or of voluntary ideas are + excited with great energy, and passing on with great vivacity, and become + dissevered by some violent stimulus, as the discharge of a pistol near + one's ear, another circumstance takes place, which is termed <font + class="sc">SURPRISE</font>; which by exciting violent irritation, and + violent sensation, employs for a time the whole sensorial energy, and + thus dissevers the passing trains of ideas, before the power of volition + has time to compare them with the usual phenomena of nature. In this case + fear is generally the companion of surprise, and adds to our + embarrassment, as every one experiences in some degree when he hears a + noise in the dark, which he cannot instantly account for. This catenation + of fear with surprise is owing to our perpetual experience of injuries + from external bodies in motion, unless we are upon our guard against + them. See Sect. <a href="#sect_XVIII_17">XVIII. 17</a>. <a + href="#sect_XIX_2">XIX. 2</a>.</p> + + <p>Many other examples of the catenations of animal motions are explained + in Sect. <a href="#sect_XXXVI">XXXVI</a>. on the Periods of Diseases.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XVIII">XVIII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF SLEEP.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XVIII_1">1</a>. <i>Volition is suspended in sleep.</i> + <a href="#sect_XVIII_2">2</a>. <i>Sensation continues. Dreams prevent + delirium and inflammation.</i> <a href="#sect_XVIII_3">3</a>. + <i>Nightmare.</i> <a href="#sect_XVIII_4">4</a>. <i>Ceaseless flow of + ideas in dreams.</i> <a href="#sect_XVIII_5">5</a>. <i>We seem to receive + them by the senses. Optic nerve perfectly sensible in sleep. Eyes less + dazzled after dreaming of visible objects.</i> <a + href="#sect_XVIII_6">6</a>. <i>Reverie, belief.</i> <a + href="#sect_XVIII_7">7</a>. <i>How we distinguish ideas from + perceptions.</i> <a href="#sect_XVIII_8">8</a>. <i>Variety of scenery in + dreams, excellence of the sense of vision.</i> <a + href="#sect_XVIII_9">9</a>. <i>Novelty of combination in dreams.</i> <a + href="#sect_XVIII_10">10</a>. <i>Distinctness of imagery in dreams.</i> + <a href="#sect_XVIII_11">11</a>. <i>Rapidity of transaction in + dreams.</i> <a href="#sect_XVIII_12">12</a>. <i>Of measuring time. Of + dramatic time and place. Why a dull play induces sleep, and an + interesting one reverie.</i> <a href="#sect_XVIII_13">13</a>. + <i>Consciousness of our existence and identity in dreams.</i> <a + href="#sect_XVIII_14">14</a>. <i>How we awake sometimes suddenly, + sometimes frequently.</i> <a href="#sect_XVIII_15">15</a>. <i>Irritative + motions continue in sleep, internal irritations are succeeded by + sensation. Sensibility increases during sleep, and irritability. Morning + dreams. Why epilepsies occur in sleep. Ecstacy of children. Case of + convulsions in sleep. Cramp, why painful. Asthma. Morning sweats. + Increase of heat. Increase of urine in sleep. Why more liable to take + cold in sleep. Catarrh from thin night-caps. Why we feel chilly at the + approach of sleep, and at waking in the open air.</i> <a + href="#sect_XVIII_16">16</a>. <i>Why the gout commences in sleep. + Secretions are more copious in sleep, young animals and plants grow more + in sleep.</i> <a href="#sect_XVIII_17">17</a>. <i>Inconsistency of + dreams. Absence of surprise in dreams.</i> <a + href="#sect_XVIII_18">18</a>. <i>Why we forget some dreams and not + others.</i> <a href="#sect_XVIII_19">19</a>. <i>Sleep-talkers awake with + surprise.</i> <a href="#sect_XVIII_20">20</a>. <i>Remote causes of sleep. + Atmosphere with less oxygene. Compression of the brain in spina bifida. + By whirling on an horizontal wheel. By cold.</i> <a + href="#sect_XVIII_21">21</a>. <i>Definition of sleep.</i></p> + +</blockquote> + + <p><a name="sect_XVIII_1">1</a>. There are four situations of our system, + which in their moderate degrees are not usually termed diseases, and yet + abound with many very curious and instructive phenomena; these are sleep, + reverie, vertigo, drunkenness. These we shall previously consider, before + we step forwards to develop the causes and cures of diseases with the + modes of the operation of medicines.</p> + + <p>As all those trains and tribes of animal motion, which are subjected + to volition, were the last that were caused, their connection is weaker + than that of the other classes; and there is a peculiar circumstance + attending this causation, which is, that it is entirely suspended during + sleep; whilst the other classes of motion, which are more immediately + necessary to life, as those caused by internal stimuli, for instance the + pulsations of the heart and arteries, or those catenated with pleasurable + sensation, as the powers of digestion, continue to strengthen their + habits without interruption. Thus though man in his sleeping state is a + much less perfect animal, than in his waking hours; and though he + consumes more than one third of his life in this his irrational + situation; yet is the wisdom of the Author of nature manifest even in + this seeming imperfection of his work!</p> + + <p>The truth of this assertion with respect to the large muscles of the + body, which are concerned in locomotion, is evident; as no one in perfect + sanity walks about in his sleep, or performs any domestic offices: and in + respect to the mind, we never exercise our reason or recollection in + dreams; we may sometimes seem distracted between contending passions, but + we never compare their objects, or deliberate about the acquisition of + those objects, if our sleep is perfect. And though many synchronous + tribes or successive trains of ideas may represent the houses or walks, + which have real existence, yet are they here introduced by their + connection with our sensations, and are in truth ideas of imagination, + not of recollection.</p> + + <p><a name="sect_XVIII_2">2</a>. For our sensations of pleasure and pain + are experienced with great vivacity in our dreams; and hence all that + motley group of ideas, which are caused by them, called the ideas of + imagination, with their various associated trains, are in a very vivid + manner acted over in the sensorium; and these sometimes call into action + the larger muscles, which have been much associated with them; as appears + from the muttering sentences, which some people utter in their dreams, + and from the obscure barking of sleeping dogs, and the motions of their + feet and nostrils.</p> + + <p>This perpetual flow of the trains of ideas, which constitute our + dreams, and which are caused by painful or pleasurable sensation, might + at first view be conceived to be an useless expenditure of sensorial + power. But it has been shewn, that those motions, which are perpetually + excited, as those of the arterial system by the stimulus of the blood, + are attended by a great accumulation of sensorial power, after they have + been for a time suspended; as the hot-fit of fever is the consequence of + the cold one. Now as these trains of ideas caused by sensation are + perpetually excited during our waking hours, if they were to be suspended + in sleep like the voluntary motions, (which are exerted only by intervals + during our waking hours,) an accumulation of sensorial power would + follow; and on our awaking a delirium would supervene, since these ideas + caused by sensation would be produced with such energy, that we should + mistake the trains of imagination for ideas excited by irritation; as + perpetually happens to people debilitated by fevers on their first + awaking; for in these fevers with debility the general quantity of + irritation being diminished, that of sensation is increased. In like + manner if the actions of the stomach, intestines, and various glands, + which are perhaps in part at least caused by or catenated with agreeable + sensation, and which perpetually exist during our waking hours, were like + the voluntary motions suspended in our sleep; the great accumulation of + sensorial power, which would necessarily follow, would be liable to + excite inflammation in them.</p> + + <p><a name="sect_XVIII_3">3</a>. When by our continued posture in sleep, + some uneasy sensations are produced, we either gradually awake by the + exertion of volition, or the muscles connected by habit with such + sensations alter the position of the body; but where the sleep is + uncommonly profound, and those uneasy sensations great, the disease + called the incubus, or nightmare, is produced. Here the desire of moving + the body is painfully exerted, by the power of moving it, or volition, is + incapable of action, till we awake. Many less disagreeable struggles in + our dreams, as when we wish in vain to fly from terrifying objects, + constitute a slighter degree of this disease. In awaking from the + nightmare I have more than once observed, that there was no disorder in + my pulse; nor do I believe the respiration is laborious, as some have + affirmed. It occurs to people whose sleep is too profound, and some + disagreeable sensation exists, which at other times would have awakened + them, and have thence prevented the disease of nightmare; as after great + fatigue or hunger with too large a supper and wine, which occasion our + sleep to be uncommonly profound. See No. <a href="#sect_XVIII_14">14</a>, + of this Section.</p> + + <p><a name="sect_XVIII_4">4</a>. As the larger muscles of the body are + much more frequently excited by volition than by sensation, they are but + seldom brought into action in our sleep: but the ideas of the mind are by + habit much more frequently connected with sensation than with volition; + and hence the ceaseless flow of our ideas in dreams. Every one's + experience will teach him this truth, for we all daily exert much + voluntary muscular motion: but few of mankind can bear the fatigue of + much voluntary thinking.</p> + + <p><a name="sect_XVIII_5">5</a>. A very curious circumstance attending + these our sleeping imaginations is, that we seem to receive them by the + senses. The muscles, which are subservient to the external organs of + sense, are connected with volition, and cease to act in sleep; hence the + eyelids are closed, and the tympanum of the ear relaxed; and it is + probable a similarity of voluntary exertion may be necessary for the + perceptions of the other nerves of sense; for it is observed that the + papillæ of the tongue can be seen to become erected, when we attempt to + taste any thing extremely grateful. Hewson Exper. Enquir. V. 2. 186. + Albini Annot. Acad. L. i. c. 15. Add to this, that the immediate organs + of sense have no objects to excite them in the darkness and silence of + the night, but their nerves of sense nevertheless continue to possess + their perfect activity subservient to all their numerous sensitive + connections. This vivacity of our nerves of sense during the time of + sleep is evinced by a circumstance, which almost every one must at some + time or other have experienced; that is, if we sleep in the daylight, and + endeavour to see some object in our dream, the light is exceedingly + painful to our eyes; and after repeated struggles we lament in our sleep, + that we cannot see it. In this case I apprehend the eyelid is in some + degree opened by the vehemence of our sensations; and, the iris being + dilated, the optic nerve shews as great or greater sensibility than in + our waking hours. See No. <a href="#sect_XVIII_15">15</a>. of this + Section.</p> + + <p>When we are forcibly waked at midnight from profound sleep, our eyes + are much dazzled with the light of the candle for a minute or two, after + there has been sufficient time allowed for the contraction of the iris; + which is owing to the accumulation of sensorial power in the organ of + vision during its state of less activity. But when we have dreamt much of + visible objects, this accumulation of sensorial power in the organ of + vision is lessened or prevented, and we awake in the morning without + being dazzled with the light, after the iris has had time to contract + itself. This is a matter of great curiosity, and may be thus tried by any + one in the day-light. Close your eyes, and cover them with your hat; + think for a minute on a tune, which you are accustomed to, and endeavour + to sing it with as little activity of mind as possible. Suddenly uncover + and open your eyes, and in one second of time the iris will contract + itself, but you will perceive the day more luminous for several seconds, + owing to the accumulation of sensorial power in the optic nerve.</p> + + <p>Then again close and cover your eyes, and think intensely on a cube of + ivory two inches diameter, attending first to the north and south sides + of it, and then to the other four sides of it; then get a clear image in + your mind's eye of all the sides of the same cube coloured red; and then + of it coloured green; and then of it coloured blue; lastly, open your + eyes as in the former experiment, and after the first second of time + allowed for the contraction of the iris, you will not perceive any + increase of the light of the day, or dazzling; because now there is no + accumulation of sensorial power in the optic nerve; that having been + expended by its action in thinking over visible objects.</p> + + <p>This experiment is not easy to be made at first, but by a few patient + trials the fact appears very certain; and shews clearly, that our ideas + of imagination are repetitions of the motions of the nerve, which were + originally occasioned by the stimulus of external bodies; because they + equally expend the sensorial power in the organ of sense. See Sect. <a + href="#sect_III_4">III. 4</a>. which is analogous to our being as much + fatigued by thinking as by labour.</p> + + <p><a name="sect_XVIII_6">6</a>. Nor is it in our dreams alone, but even + in our waking reveries, and in great efforts of invention, so great is + the vivacity of our ideas, that we do not for a time distinguish them + from the real presence of substantial objects; though the external organs + of sense are open, and surrounded with their usual stimuli. Thus whilst I + am thinking over the beautiful valley, through which I yesterday + travelled, I do not perceive the furniture of my room: and there are + some, whose waking imaginations are so apt to run into perfect reverie, + that in their common attention to a favourite idea they do not hear the + voice of the companion, who accosts them, unless it is repeated with + unusual energy.</p> + + <p>This perpetual mistake in dreams and reveries, where our ideas of + imagination are attended with a belief of the presence of external + objects, evinces beyond a doubt, that all our ideas are repetitions of + the motions of the nerves of sense, by which they were acquired; and that + this belief is not, as some late philosophers contend, an instinct + necessarily connected only with our perceptions.</p> + + <p><a name="sect_XVIII_7">7</a>. A curious question demands our attention + in this place; as we do not distinguish in our dreams and reveries + between our perceptions of external objects, and our ideas of them in + their absence, how do we distinguish them at any time? In a dream, if the + sweetness of sugar occurs to my imagination, the whiteness and hardness + of it, which were ideas usually connected with the sweetness, immediately + follow in the train; and I believe a material lump of sugar present + before my senses: but in my waking hours, if the sweetness occurs to my + imagination, the stimulus of the table to my hand, or of the window to my + eye, prevents the other ideas of the hardness and whiteness of the sugar + from succeeding; and hence I perceive the fallacy, and disbelieve the + existence of objects correspondent to those ideas, whose tribes or trains + are broken by the stimulus of other objects. And further in our waking + hours, we frequently exert our volition in comparing present appearances + with such, as we have usually observed; and thus correct the errors of + one sense by our general knowledge of nature by intuitive analogy. See + Sect. <a href="#sect_XVII_3_7">XVII. 3. 7</a>. Whereas in dreams the + power of volition is suspended, we can recollect and compare our present + ideas with none of our acquired knowledge, and are hence incapable of + observing any absurdities in them.</p> + + <p>By this criterion we distinguish our waking from our sleeping hours, + we can voluntarily recollect our sleeping ideas, when we are awake, and + compare them with our waking ones; but we cannot in our sleep + <i>voluntarily</i> recollect our waking ideas at all.</p> + + <p><a name="sect_XVIII_8">8</a>. The vast variety of scenery, novelty of + combination, and distinctness of imagery, are other curious circumstances + of our sleeping imaginations. The variety of scenery seems to arise from + the superior activity and excellence of our sense of vision; which in an + instant unfolds to the mind extensive fields of pleasurable ideas; while + the other senses collect their objects slowly, and with little + combination; add to this, that the ideas, which this organ presents us + with, are more frequently connected with our sensation than those of any + other.</p> + + <p><a name="sect_XVIII_9">9</a>. The great novelty of combination is + owing to another circumstance; the trains of ideas, which are carried on + in our waking thoughts, are in our dreams dissevered in a thousand places + by the suspension of volition, and the absence of irritative ideas, and + are hence perpetually falling into new catenations. As explained in Sect. + <a href="#sect_XVII_1_9">XVII. 1. 9</a>. For the power of volition is + perpetually exerted during our waking hours in comparing our passing + trains of ideas with our acquired knowledge of nature, and thus forms + many intermediate links in their catenation. And the irritative ideas + excited by the stimulus of the objects, with which we are surrounded, are + every moment intruded upon us, and form other links of our unceasing + catenations of ideas.</p> + + <p><a name="sect_XVIII_10">10</a>. The absence of the stimuli of external + bodies, and of volition, in our dreams renders the organs of sense liable + to be more strongly affected by the powers of sensation, and of + association. For our desires or aversions, or the obtrusions of + surrounding bodies, dissever the sensitive and associate tribes of ideas + in our waking hours by introducing those of irritation and volition + amongst them. Hence proceeds the superior distinctness of pleasurable or + painful imagery in our sleep; for we recal the figure and the features of + a long lost friend, whom we loved, in our dreams with much more accuracy + and vivacity than in our waking thoughts. This circumstance contributes + to prove, that our ideas of imagination are reiterations of those motions + of our organs of sense, which were excited by external objects; because + while we are exposed to the stimuli of present objects, our ideas of + absent objects cannot be so distinctly formed.</p> + + <p><a name="sect_XVIII_11">11</a>. The rapidity of the succession of + transactions in our dreams is almost inconceivable; insomuch that, when + we are accidentally awakened by the jarring of a door, which is opened + into our bed-chamber, we sometimes dream a whole history of thieves or + fire in the very instant of awaking.</p> + + <p>During the suspension of volition we cannot compare our other ideas + with those of the parts of time in which they exist; that is, we cannot + compare the imaginary scene, which is before us, with those changes of + it, which precede or follow it: because this act of comparing requires + recollection or voluntary exertion. Whereas in our waking hours, we are + perpetually making this comparison, and by that means our waking ideas + are kept confident with each other by intuitive analogy; but this + companion retards the succession of them, by occasioning their + repetition. Add to this, that the transactions of our dreams consist + chiefly of visible ideas, and that a whole history of thieves and fire + may be <i>beheld</i> in an instant of time like the figures in a + picture.</p> + + <p><a name="sect_XVIII_12">12</a>. From this incapacity of attending to + the parts of time in our dreams, arises our ignorance of the length of + the night; which, but from our constant experience to the contrary, we + should conclude was but a few minutes, when our sleep is perfect. The + same happens in our reveries; thus when we are possessed with vehement + joy, grief, or anger, time appears short, for we exert no volition to + compare the present scenery with the past or future; but when we are + compelled to perform those exercises of mind or body, which, are unmixed + with passion, as in travelling over a dreary country, time appears long; + for our desire to finish our journey occasions us more frequently to + compare our present situation with the parts of time or place, which are + before and behind us.</p> + + <p>So when we are enveloped in deep contemplation of any kind, or in + reverie, as in reading a very interesting play or romance, we measure + time very inaccurately; and hence, if a play greatly affects our + passions, the absurdities of passing over many days or years, and or + perpetual changes of place, are not perceived by the audience; as is + experienced by every one, who reads or sees some plays of the immortal + Shakespear; but it is necessary for inferior authors to observe those + rules of the <span lang="el" title="pithanon" + >πιθανον</span> and <span + lang="el" title="prepon" + >πρεπον</span> inculcated by + Aristotle, because their works do not interest the passions sufficiently + to produce complete reverie.</p> + + <p>Those works, however, whether a romance or a sermon, which do not + interest us so much as to induce reverie, may nevertheless incline us to + sleep. For those pleasurable ideas, which are presented to us, and are + too gentle to excite laughter, (which is attended with interrupted + voluntary exertions, as explained Sect. <a href="#sect_XXXIV_1_4">XXXIV. + 1. 4</a>.) and which are not accompanied with any other emotion, which + usually excites some voluntary exertion, as anger, or fear, are liable to + produce sleep; which consists in a suspension of all voluntary power. But + if the ideas thus presented to us, and interest our attention, are + accompanied with so much pleasurable or painful sensation as to excite + our voluntary exertion at the same time, reverie is the consequence. + Hence an interesting play produces reverie, a tedious one produces sleep: + in the latter we become exhausted by attention, and are not excited to + any voluntary exertion, and therefore sleep; in the former we are excited + by some emotion, which prevents by its pain the suspension of volition, + and in as much as it interests us, induces reverie, as explained in the + next Section.</p> + + <p>But when our sleep is imperfect, as when we have determined to rise in + half an hour, time appears longer to us than in most other situations. + Here our solicitude not to oversleep the determined time induces us in + this imperfect sleep to compare the quick changes of imagined scenery + with the parts of time or place, they would have taken up, had they real + exigence; and that more frequently than in our waking hours; and hence + the time appears longer to us: and I make no doubt, but the permitted + time appears long to a man going to the gallows, as the fear of its quick + lapse will make him think frequently about it.</p> + + <p><a name="sect_XVIII_13">13</a>. As we gain our knowledge of time by + comparing the present scenery with the past and future, and of place by + comparing the situations of objects with each other; so we gain our idea + of consciousness by comparing ourselves with the scenery around us; and + of identity by comparing our present consciousness with our past + consciousness: as we never think of time or place, but when we make the + companions above mentioned, so we never think of consciousness, but when + we compare our own existence with that of other objects; nor of identity, + but when we compare our present and our past consciousness. Hence the + consciousness of our own existence, and of our identity, is owing to a + voluntary exertion of our minds: and on that account in our complete + dreams we neither measure time, are surprised at the sudden changes of + place, nor attend to our own existence, or identity; because our power of + volition is suspended. But all these circumstances are more or less + observable in our incomplete ones; for then we attend a little to the + lapse of time, and the changes of place, and to our own existence; and + even to our identity of person; for a lady seldom dreams, that she is a + soldier; nor a man, that he is brought to bed.</p> + + <p><a name="sect_XVIII_14">14</a>. As long as our sensations only excite + their sensual motions, or ideas, our sleep continues sound; but as soon + as they excite desires or aversions, our sleep becomes imperfect; and + when that desire or aversion is so strong, as to produce voluntary + motions, we begin to awake; the larger muscles of the body are brought + into action to remove that irritation or sensation, which a continued + posture has caused; we stretch our limbs, and yawn, and our sleep is thus + broken by the accumulation of voluntary power.</p> + + <p>Sometimes it happens, that the act of waking is suddenly produced, and + this soon after the commencement of sleep; which is occasioned by some + sensation so disagreeable, as instantaneously to excite the power of + volition; and a temporary action of all the voluntary motions suddenly + succeeds, and we start awake. This is sometimes accompanied with loud + noise in the ears, and with some degree of fear; and when it is in great + excess, so as to produce continued convulsive motions of those muscles, + which are generally subservient to volition, it becomes epilepsy: the + fits of which in some patients generally commence during sleep. This + differs from the night-mare described in No. <a + href="#sect_XVIII_3">3</a>. of this Section, because in that the + disagreeable sensation is not so great as to excite the power of volition + into action; for as soon as that happens, the disease ceases.</p> + + <p>Another circumstance, which sometimes awakes people soon after the + commencement of their sleep, is where the voluntary power is already so + great in quantity as almost to prevent them from falling asleep, and then + a little accumulation of it soon again awakens them; this happens in + cases of insanity, or where the mind has been lately much agitated by + fear or anger. There is another circumstance in which sleep is likewise + of short duration, which arises from great debility, as after great + over-fatigue, and in some fevers, where the strength of the patient is + greatly diminished, as in these cases the pulse intermits or flutters, + and the respiration is previously affected, it seems to originate from + the want of some voluntary efforts to facilitate respiration, as when we + are awake. And is further treated of in Vol. II. Class I. 2. 1. 2. on the + Diseases of the Voluntary Power. Art. Somnus interruptus.</p> + + <p><a name="sect_XVIII_15">15</a>. We come now to those motions which + depend on irritation. The motions of the arterial and glandular systems + continue in our sleep, proceeding slower indeed, but stronger and more + uniformly, than in our waking hours, when they are incommoded by external + stimuli, or by the movements of volition; the motions of the muscles + subservient to respiration continue to be stimulated into action, and the + other internal senses of hunger, thirst, and lust, are not only + occasionally excited in our sleep, but their irritative motions are + succeeded by their usual sensations, and make a part of the farrago of + our dreams. These sensations of the want of air, of hunger, thirst, and + lust, in our dreams, contribute to prove, that the nerves of the external + senses are also alive and excitable in our sleep; but as the stimuli of + external objects are either excluded from them by the darkness and + silence of the night, or their access to them is prevented by the + suspension of volition, these nerves of sense fall more readily into + their connexions with sensation and with association; because much + sensorial power, which during the day was expended in moving the external + organs of sense in consequence of irritation from external stimuli, or in + consequence of volition, becomes now in some degree accumulated, and + renders the internal or immediate organs of sense more easily excitable + by the other sensorial powers. Thus in respect to the eye, the irritation + from external stimuli, and the power of volition during our waking hours, + elevate the eye-lids, adapt the aperture of the iris to the quantity of + light, the focus of the crystalline humour, and the angle of the optic + axises to the distance of the object, all which perpetual activity during + the day expends much sensorial power, which is saved during our + sleep.</p> + + <p>Hence it appears, that not only those parts of the system, which are + always excited by internal stimuli, as the stomach, intestinal canal, + bile-ducts, and the various glands, but the organs of sense also may be + more violently excited into action by the irritation from internal + stimuli, or by sensation, during our sleep than in our waking hours; + because during the suspension of volition, there is a greater quantity of + the spirit of animation to be expended by the other sensorial powers. On + this account our irritability to internal stimuli, and our sensibility to + pain or pleasure, is not only greater in sleep, but increases as our + sleep is prolonged. Whence digestion and secretion are performed better + in sleep, than in our waking hours, and our dreams in the morning have + greater variety and vivacity, as our sensibility increases, than at night + when we first lie down. And hence epileptic fits, which are always + occasioned by some disagreeable sensation, so frequently attack those, + who are subject to them, in their sleep; because at this time the system + is more excitable by painful sensation in consequence of internal + stimuli; and the power of volition is then suddenly exerted to relieve + this pain, as explained Sect. <a href="#sect_XXXIV_1_4">XXXIV. 1. + 4</a>.</p> + + <p>There is a disease, which frequently affects children in the cradle, + which is termed ecstasy, and seems to consist in certain exertions to + relieve painful sensation, in which the voluntary power is not so far + excited as totally to awaken them, and yet is sufficient to remove the + disagreeable sensation, which excites it; in this case changing the + posture of the child frequently relieves it.</p> + + <p>I have at this time under my care an elegant young man about + twenty-two years of age, who seldom sleeps more than an hour without + experiencing a convulsion fit; which ceases in about half a minute + without any subsequent stupor. Large doses of opium only prevented the + paroxysms, so long as they prevented him from sleeping by the + intoxication, which they induced. Other medicines had no effect on him. + He was gently awakened every half hour for one night, but without good + effect, as he soon slept again, and the fit returned at about the same + periods of time, for the accumulated sensorial power, which occasioned + the increased sensibility to pain, was not thus exhausted. This case + evinces, that the sensibility of the system to internal excitation + increases, as our sleep is prolonged; till the pain thus occasioned + produces voluntary exertion; which, when it is in its usual degree, only + awakens us; but when it is more violent, it occasions convulsions.</p> + + <p>The cramp in the calf of the leg is another kind of convulsion, which + generally commences in sleep, occasioned by the continual increase of + irritability from internal stimuli, or of sensibility, during that state + of our existence. The cramp is a violent exertion to relieve pain, + generally either of the skin from cold, or of the bowels, as in some + diarrhœas, or from the muscles having been previously overstretched, + as in walking up or down steep hills. But in these convulsions of the + muscles, which form the calf of the leg, the contraction is so violent as + to occasion another pain in consequence of their own too violent + contraction; as soon as the original pain, which caused the contraction, + is removed. And hence the cramp, or spasm, of these muscles is continued + without intermission by this new pain, unlike the alternate convulsions + and remissions in epileptic fits. The reason, that the contraction of + these muscles of the calf of the leg is more violent during their + convulsion than that of others, depends on the weakness of their + antagonist muscles; for after these have been contracted in their usual + action, as at every step in walking, they are again extended, not, as + most other muscles are, by their antagonists, but by the weight 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.</p> + + <p>Another disease, the periods of which generally commence during our + sleep, is the asthma. Whatever may be the remote cause of paroxysms of + asthma, the immediate cause of the convulsive respiration, whether in the + common asthma, or in what is termed the convulsive asthma, which are + perhaps only different degrees of the same disease, must be owing to + violent voluntary exertions to relieve pain, as in other convulsions; and + the increase of irritability to internal stimuli, or of sensibility, + during sleep must occasion them to commence at this time.</p> + + <p>Debilitated people, who have been unfortunately accustomed to great + ingurgitation of spirituous potation, frequently part with a great + quantity of water during the night, but with not more than usual in the + day-time. This is owing to a beginning torpor of the absorbent system, + and precedes anasarca, which commences in the day, but is cured in the + night by the increase of the irritability of the absorbent system during + sleep, which thus imbibes from the cellular membrane the fluids, which + had been accumulated there during the day; though it is possible the + horizontal position of the body may contribute something to this purpose, + and also the greater irritability of some branches of the absorbent + vessels, which open their mouths in the cells of the cellular membrane, + than that of other branches.</p> + + <p>As soon as a person begins to sleep, the irritability and sensibility + of the system begins to increase, owing to the suspension of volition and + the exclusion of external stimuli. Hence the actions of the vessels in + obedience to internal stimulation become stronger and more energetic, + though less frequent in respect to number. And as many of the secretions + are increased, so the heat of the system is gradually increased, and the + extremities of feeble people, which had been cold during the day, become + warm. Till towards morning many people become so warm, as to find it + necessary to throw off some of their bed-clothes, as soon as they awake; + and in others sweats are so liable to occur towards morning during their + sleep.</p> + + <p>Thus those, who are not accustomed to sleep in the open air, are very + liable to take cold, if they happen to fall asleep on a garden bench, or + in a carriage with the window open. For as the system is warmer during + sleep, as above explained, if a current of cold air affects any part of + the body, a torpor of that part is more effectually produced, as when a + cold blast of air through a key-hole or casement falls upon a person in a + warm room. In those cases the affected part possesses less irritability + in respect to heat, from its having previously been exposed to a greater + stimulus of heat, as in the warm room, or during sleep; and hence, when + the stimulus of heat is diminished, a torpor is liable to ensue; that is, + we take cold. Hence people who sleep in the open air, generally feel + chilly both at the approach of sleep, and on their awaking; and hence + many people are perpetually subject to catarrhs if they sleep in a less + warm head-dress, than that which they wear in the day.</p> + + <p><a name="sect_XVIII_16">16</a>. Not only the sensorial powers of + irritation and of sensation, but that of association also appear to act + with greater vigour during the suspension of volition in sleep. It will + be shewn in another place, that the gout generally first attacks the + liver, and that afterwards an inflammation of the ball of the great toe + commences by association, and that of the liver ceases. Now as this + change or metastasis of the activity of the system generally commences in + sleep, it follows, that these associations of motion exist with greater + energy at that time; that is, that the sensorial faculty of association, + like those of irritation and of sensation, becomes in some measure + accumulated during the suspension of volition.</p> + + <p>Other associate tribes and trains of motions, as well as the + irritative and sensitive ones, appear to be increased in their activity + during the suspension of volition in sleep. As those which contribute to + circulate the blood, and to perform the various secretions; as well as + the associate tribes and trains of ideas, which contribute to furnish the + perpetual dreams of our dreaming imaginations.</p> + + <p>In sleep the secretions have generally been supposed to be diminished, + as the expectorated mucus in coughs, the fluids discharged in + diarrhœas, and in salivation, except indeed the secretion of sweat, + which is often visibly increased. This error seems to have arisen from + attention to the excretions rather than to the secretions. For the + secretions, except that of sweat, are generally received into reservoirs, + as the urine into the bladder, and the mucus of the intestines and lungs + into their respective cavities; but these reservoirs do not exclude these + fluids immediately by their stimulus, but require at the same time some + voluntary efforts, and therefore permit them to remain during sleep. And + as they thus continue longer in those receptacles in our sleeping hours, + a greater part is absorbed from them, and the remainder becomes thicker, + and sometimes in less quantity, though at the time it was secreted the + fluid was in greater quantity than in our waking hours. Thus the urine is + higher coloured after long sleep; which shews that a greater quantity has + been secreted, and that more of the aqueous and saline part has been + reabsorbed, and the earthy part left in the bladder; hence thick urine in + fevers shews only a greater action of the vessels which secrete it in the + kidneys, and of those which absorb it from the bladder.</p> + + <p>The same happens to the mucus expectorated in coughs, which is thus + thickened by absorption of its aqueous and saline parts; and the same of + the feces of the intestines. From hence it appears, and from what has + been said in No. <a href="#sect_XVIII_15">15</a>. of this Section + concerning the increase of irritability and of sensibility during sleep, + that the secretions are in general rather increased than diminished + during these hours of our existence; and it is probable that nutrition is + almost entirely performed in sleep; and that young animals grow more at + this time than in their waking hours, as young plants have long since + been observed to grow more in the night, which is their time of + sleep.</p> + + <p><a name="sect_XVIII_17">17</a>. Two other remarkable circumstances of + our dreaming ideas are their inconsistency, and the total absence of + surprise. Thus we seem to be present at more extraordinary metamorphoses + of animals or trees, than are to be met with in the fables of antiquity; + and appear to be transported from place to place, which seas divide, as + quickly as the changes of scenery are performed in a play-house; and yet + are not sensible of their inconsistency, nor in the least degree affected + with surprise.</p> + + <p>We must consider this circumstance more minutely. In our waking trains + of ideas, those that are inconsistent with the usual order of nature, so + rarely have occurred to us, that their connexion is the slightest of all + others: hence, when a consistent train of ideas is exhausted, we attend + to the external stimuli, that usually surround us, rather than to any + inconsistent idea, which might otherwise present itself; and if an + inconsistent idea should intrude itself, we immediately compare it with + the preceding one, and voluntarily reject the train it would introduce; + this appears further in the Section on Reverie, in which state of the + mind external stimuli are not attended to, and yet the streams of ideas + are kept consistent by the efforts of volition. But as our faculty of + volition is suspended, and all external stimuli are excluded in sleep, + this slighter connexion of ideas takes place; and the train is said to be + inconsistent; that is, dissimilar to the usual order of nature.</p> + + <p>But, when any consistent train of sensitive or voluntary ideas is + flowing along, if any external stimulus affects us so violently, as to + intrude irritative ideas forcibly into the mind, it disunites the former + train of ideas, and we are affected with surprise. These stimuli of + unusual energy or novelty not only disunite our common trains of ideas, + but the trains of muscular motions also, which have not been long + established by habit, and disturb those that have. Some people become + motionless by great surprise, the fits of hiccup and or ague have been + often removed by it, and it even affects the movements of the heart, and + arteries; but in our sleep, all external stimuli are excluded, and in + consequence no surprise can exist. See Section <a + href="#sect_XVII_3_7">XVII. 3. 7</a>.</p> + + <p><a name="sect_XVIII_18">18</a>. We frequently awake with pleasure from + a dream, which has delighted us, without being able to recollect the + transactions of it; unless perhaps at a distance of time, some analogous + idea may introduce afresh this forgotten train: and in our waking + reveries we sometimes in a moment lose the train of thought, but continue + to feel the glow of pleasure, or the depression of spirits, it + occasioned: whilst at other times we can retrace with ease these + histories of our reveries and dreams.</p> + + <p>The above explanation of surprise throws light upon this subject. When + we are suddenly awaked by any violent stimulus, the surprise totally + disunites the trains of our sleeping ideas from these of our waking ones; + but if we gradually awake, this does not happen; and we readily unravel + the preceding trains of imagination.</p> + + <p><a name="sect_XVIII_19">19</a>. There are various degrees of surprise; + the more intent we are upon the train of ideas, which we are employed + about, the more violent must be the stimulus that interrupts them, and + the greater is the degree of surprise. I have observed dogs, who have + slept by the fire, and by their obscure barking and struggling have + appeared very intent on their prey, that shewed great surprise for a few + seconds 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 speaks much and articulately + in her sleep, could never recollect her dreams in the morning, when this + happened to her: but that when she did not speak in her sleep, she could + always recollect them.</p> + + <p>Hence, when our sensations act so strongly in sleep as to influence + the larger muscles, as in those, who talk or struggle in their dreams; or + in those, who are affected with complete reverie (as described in the + next Section), great surprise is produced, when they awake; and these as + well as those, who are completely drunk or delirious, totally forget + afterwards their imaginations at those times.</p> + + <p><a name="sect_XVIII_20">20</a>. As the immediate cause of sleep + consists in the suspension of volition, it follows, that whatever + diminishes the general quantity of sensorial power, or derives it from + the faculty of volition, will constitute a remote cause of sleep; such as + fatigue from muscular or mental exertion, which diminishes the general + quantity of sensorial power; or an increase of the sensitive motions, as + by attending to soft music, which diverts the sensorial power from the + faculty of volition; or lastly, by increase of the irritative motions, as + by wine, or food; or warmth; which not only by their expenditure of + sensorial power diminish the quantity of volition; but also by their + producing pleasureable sensations (which occasion other muscular or + sensual motions in consequence), doubly decrease the voluntary power, and + thus more forcibly produce sleep. See Sect. <a + href="#sect_XXXIV_1_4">XXXIV. 1. 4</a>.</p> + + <p>Another method of inducing sleep is delivered in a very ingenious work + lately published by Dr. Beddoes. Who, after lamenting that opium + frequently occasions restlessness, thinks, "that in most cases it would + be better to induce sleep by the abstraction of stimuli, than by + exhausting the excitability;" and adds, "upon this principle we could not + have a better soporific than an atmosphere with a diminished proportion + of oxygene air, and that common air might be admitted after the patient + was asleep." (Observ. on Calculus, &c. by Dr. Beddoes, Murray.) If it + should be found to be true, that the excitability of the system depends + on the quantity of oxygene absorbed by the lungs in respiration according + to the theory of Dr. Beddoes, and of M. Girtanner, this idea of sleeping + in an atmosphere with less oxygene in its composition might be of great + service in epileptic cases, and in cramp, and even in fits of the asthma, + where their periods commence from the increase of irritability during + sleep.</p> + + <p>Sleep is likewise said to be induced by mechanic pressure on the brain + in the cases of spina bifida. Where there has been a defect of one of the + vertebræ of the back, a tumour is protruded in consequence; and, whenever + this tumour has been compressed by the hand, sleep is said to be induced, + because the whole of the brain both within the head and spine becomes + compressed by the retrocession of the fluid within the tumour. But by + what means a compression of the brain induces sleep has not been + explained, but probably by diminishing the secretion of sensorial power, + and then the voluntary motions become suspended previously to the + irritative ones, as occurs in most dying persons.</p> + + <p>Another way of procuring sleep mechanically was related to me by Mr. + Brindley, the famous canal engineer, who was brought up to the business + of a mill-wright; he told me, that he had more than once seen the + experiment of a man extending himself across the large stone of a + corn-mill, and that by gradually letting the stone whirl, the man fell + asleep, before the stone had gained its full velocity, and he supposed + would have died without pain by the continuance or increase of the + motion. In this case the centrifugal motion of the head and feet must + accumulate the blood in both those extremities of the body, and thus + compress the brain.</p> + + <p>Lastly, we should mention the application of cold; which, when in a + less degree, produces watchfulness by the pain it occasions, and the + tremulous convulsions of the subcutaneous muscles; but when it is applied + in great degree, is said to produce sleep. To explain this effect it has + been said, that as the vessels of the skin and extremities become first + torpid by the want of the stimulus of heat, and as thence less blood is + circulated through them, as appears from their paleness, a greater + quantity of blood poured upon the brain produces sleep by its compression + of that organ. But I should rather imagine, that the sensorial power + becomes exhausted by the convulsive actions in consequence of the pain of + cold, and of the voluntary exercise previously used to prevent it, and + that the sleep is only the beginning to die, as the suspension of + voluntary power in lingering deaths precedes for many hours the + extinction of the irritative motions.</p> + + <p><a name="sect_XVIII_21">21</a>. The following are the characteristic + circumstances attending perfect sleep.</p> + + <p>1. The power of volition is totally suspended.</p> + + <p>2. The trains of ideas caused by sensation proceed with greater + facility and vivacity; but become inconsistent with the usual order of + nature. The muscular motions caused by sensation continue; as those + concerned in our evacuations during infancy, and afterwards in digestion, + and in priapismus.</p> + + <p>3. The irritative muscular motions continue, as those concerned in the + circulation, in secretion, in respiration. But the irritative sensual + motions, or ideas, are not excited; as the immediate organs of sense are + not stimulated into action by external objects, which are excluded by the + external organs of sense; which are not in sleep adapted to their + reception by the power of volition, as in our waking hours.</p> + + <p>4. The associate motions continue; but their first link is not excited + into action by volition, or by external stimuli. In all respects, except + those above mentioned, the three last sensorial powers are somewhat + increased in energy during the suspension of volition, owing to the + consequent accumulation of the spirit of animation.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XIX">XIX</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF REVERIE.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XIX_1">1</a>. <i>Various degrees of reverie.</i> <a + href="#sect_XIX_2">2</a>. <i>Sleep-walkers. Case of a young lady. Great + surprise at awaking. And total forgetfulness of what passed in + reverie.</i> <a href="#sect_XIX_3">3</a>. <i>No suspension of volition in + reverie.</i> <a href="#sect_XIX_4">4</a>. <i>Sensitive motions continue, + and are consistent.</i> <a href="#sect_XIX_5">5</a>. <i>Irritative + motions continue, but are not succeeded by sensation.</i> <a + href="#sect_XIX_6">6</a>. <i>Volition necessary for the perception of + feeble impressions.</i> <a href="#sect_XIX_7">7</a>. <i>Associated + motions continue.</i> <a href="#sect_XIX_8">8</a>. <i>Nerves of sense are + irritable in sleep, but not in reverie.</i> <a href="#sect_XIX_9">9</a>. + <i>Somnambuli are not asleep. Contagion received but once.</i> <a + href="#sect_XIX_10">10</a>. <i>Definition of reverie.</i></p> + +</blockquote> + + <p><a name="sect_XIX_1">1</a>. When we are employed with great sensation + of pleasure, or with great efforts of volition, in the pursuit of some + interesting train of ideas, we cease to be conscious of our existence, + are inattentive to time and place, and do not distinguish this train of + sensitive and voluntary ideas from the irritative ones excited by the + presence of external objects, though our organs of sense are furnished + with their accustomed stimuli, till at length this interesting train of + ideas becomes exhausted, or the appulses of external objects are applied + with unusual violence, and we return with surprise, or with regret, into + the common track of life. This is termed reverie or studium.</p> + + <p>In some constitutions these reveries continue a considerable time, and + are not to be removed without greater difficulty, but are experienced in + a less degree by us all; when we attend earnestly to the ideas excited by + volition or sensation, with their associated connexions, but are at the + same time conscious at intervals of the stimuli of surrounding bodies. + Thus in being present at a play, or in reading a romance, some persons + are so totally absorbed as to forget their usual time of sleep, and to + neglect their meals; while others are said to have been so involved in + voluntary study as not to have heard the discharge of artillery; and + there is a story of an Italian politician, who could think so intensely + on other subjects, as to be insensible to the torture of the rack.</p> + + <p>From hence it appears, that these catenations of ideas and muscular + motions, which form the trains of reverie, are composed both of voluntary + and sensitive associations of them; and that these ideas differ from + those of delirium or of sleep, as they are kept consistent by the power + of volition; and they differ also from the trains of ideas belonging to + insanity, as they are as frequently excited by sensation as by volition. + But lastly, that the whole sensorial power is so employed on these trains + of complete reverie, that like the violent efforts of volition, as in + convulsions or insanity; or like the great activity of the irritative + motions in drunkenness; or of the sensitive motions in delirium; they + preclude all sensation consequent to external stimulus.</p> + + <p><a name="sect_XIX_2">2</a>. Those persons, who are said to walk in + their sleep, are affected with reverie to so great a degree, that it + becomes a formidable disease; the essence of which consists in the + inaptitude of the mind to attend to external stimuli. Many histories of + this disease have been published by medical writers; of which there is a + very curious one in the Lausanne Transactions. I shall here subjoin an + account of such a case, with its cure, for the better illustration of + this subject.</p> + + <p>A very ingenious and elegant young lady, with light eyes and hair, + about the age of seventeen, in other respects well, was suddenly seized + soon after her usual menstruation with this very wonderful malady. The + disease began with vehement convulsions of almost every muscle of her + body, with great but vain efforts to vomit, and the most violent + hiccoughs, that can be conceived: these were succeeded in about an hour + with a fixed spasm; in which one hand was applied to her head, and the + other to support it: in about half an hour these ceased, and the reverie + began suddenly, and was at first manifest by the look of her eyes and + countenance, which seemed to express attention. Then she conversed aloud + with imaginary persons with her eyes open, and could not for about an + hour be brought to attend to the stimulus of external objects by any kind + of violence, which it was proper to use; these symptoms returned in this + order every day for five or six weeks.</p> + + <p>These conversations were quite consistent, and we could understand, + what she supposed her imaginary companions to answer, by the continuation + of her part of the discourse. Sometimes she was angry, at other times + shewed much wit and vivacity, but was most frequently inclined to + melancholy. In these reveries she sometimes sung over some music with + accuracy, and repeated whole pages from the English poets. In repeating + some lines from Mr. Pope's works she had forgot one word, and began + again, endeavouring to recollect it; when she came to the forgotten word, + it was shouted aloud in her ear, and this repeatedly, to no purpose; but + by many trials she at length regained it herself.</p> + + <p>These paroxysms were terminated with the appearance of inexpressible + surprise, and great fear, from which she was some minutes in recovering + herself, calling on her sister with great agitation, and very frequently + underwent a repetition of convulsions, apparently from the pain of fear. + See Sect. <a href="#sect_XVII_3_7">XVII. 3. 7</a>.</p> + + <p>After having thus returned for about an hour every day for two or + three weeks, the reveries seemed to become less complete, and some of + their circumstances varied; so that she could walk about the room in them + without running against any of the furniture; though these motions were + at first very unsteady and tottering. And afterwards she once drank a + dish of tea, when the whole apparatus of the tea-table was set before + her; and expressed some suspicion, that a medicine was put into it, and + once seemed to smell of a tuberose, which was in flower in her chamber, + and deliberated aloud about breaking it from the stem, saying, "it would + make her sister so charmingly angry." At another time in her melancholy + moments she heard the sound of a passing bell, "I wish I was dead," she + cried, listening to the bell, and then taking off one of her shoes, as + she sat upon the bed, "I love the colour black," says she, "a little + wider, and a little longer, even this might make me a coffin!"—Yet + it is evident, she was not sensible at this time, any more than formerly, + of seeing or hearing any person about her; indeed when great light was + thrown upon her by opening the shutters of the window, her trains of + ideas seemed less melancholy; and when I have forcibly held her hands, or + covered her eyes, she appeared to grow impatient, and would say, she + could not tell what to do, for she could neither see nor move. In all + these circumstances her pulse continued unaffected as in health. And when + the paroxysm was over, she could never recollect a single idea of what + had passed in it.</p> + + <p>This astonishing disease, after the use of many other medicines and + applications in vain, was cured by very large doses of opium given about + an hour before the expected returns of the paroxysms; and after a few + relapses, at the intervals of three or four months, entirely disappeared. + But she continued at times to have other symptoms of epilepsy.</p> + + <p><a name="sect_XIX_3">3</a>. We shall only here consider, what happened + during the time of her reveries, as that is our present subject; the fits + of convulsion belong to another part of this treatise. Sect. <a + href="#sect_XXXIV_1_4">XXXIV. 1. 4</a>.</p> + + <p>There seems to have been no suspension of volition during the fits of + reverie, because she endeavoured to regain the lost idea in repeating the + lines of poetry, and deliberated about breaking the tuberose, and + suspected the tea to have been medicated.</p> + + <p><a name="sect_XIX_4">4</a>. The ideas and muscular movements depending + on sensation were exerted with their usual vivacity, and were kept from + being inconsistent by the power of volition, as appeared from her whole + conversation, and was explained in Sect. <a href="#sect_XVII_3_7">XVII. + 3. 7</a>. and <a href="#sect_XVIII_16">XVIII. 16</a>.</p> + + <p><a name="sect_XIX_5">5</a>. The ideas and motions dependant on + irritation during the first weeks of her disease, whilst the reverie was + complete, were never succeeded by the sensation of pleasure or pain; as + she neither saw, heard, nor felt any of the surrounding objects. Nor was + it certain that any irritative motions succeeded the stimulus of external + objects, till the reverie became less complete, and then she could walk + about the room without running against the furniture of it. Afterwards, + when the reverie became still less complete from the use of opium, some + few irritations were at times succeeded by her attention to them. As when + she smelt at a tuberose, and drank a dish of tea, but this only when she + seemed voluntarily to attend to them.</p> + + <p><a name="sect_XIX_6">6</a>. In common life when we listen to distant + sounds, or wish to distinguish objects in the night, we are obliged + strongly to exert our volition to dispose the organs of sense to perceive + them, and to suppress the other trains of ideas, which might interrupt + these feeble sensations. Hence in the present history the strongest + stimuli were not perceived, except when the faculty of volition was + exerted on the organ of sense; and then even common stimuli were + sometimes perceived: for her mind was so strenuously employed in pursuing + its own trains of voluntary or sensitive ideas, that no common stimuli + could so far excite her attention as to disunite them; that is, the + quantity of volition or of sensation already existing was greater than + any, which could be produced in consequence of common degrees of + stimulation. But the few stimuli of the tuberose, and of the tea, which + she did perceive, were such, as accidentally coincided with the trains of + thought, which were passing in her mind; and hence did not disunite those + trains, and create surprise. And their being perceived at all was owing + to the power of volition preceding or coinciding with that of + irritation.</p> + + <p>This explication is countenanced by a fact mentioned concerning a + somnambulist in the Lausanne Transactions, who sometimes opened his eyes + for a short time to examine, where he was, or where his ink-pot stood, + and then shut 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 some errors of the + pen, or in spelling: so much easier was it to him to refer to his ideas + of the positions of things, than to his perceptions of them.</p> + + <p><a name="sect_XIX_7">7</a>. The associated motions persisted in their + usual channel, as appeared by the combinations of her ideas, and the use + of her muscles, and the equality of her pulse; for the natural motions of + the arterial system, though originally excited like other motions by + stimulus, seem in part to continue by their association with each other. + As the heart of a viper pulsates long after it is cut out of the body, + and removed from the stimulus of the blood.</p> + + <p><a name="sect_XIX_8">8</a>. In the section on sleep, it was observed + that the nerves of sense are equally alive and susceptible to irritation + in that state, as when we are awake; but that they are secluded from + stimulating objects, or rendered unfit to receive them: but in complete + reverie the reverse happens, the immediate organs of sense are exposed to + their usual stimuli; but are either not excited into action at all, or + not into so great action, as to produce attention or sensation.</p> + + <p>The total forgetfulness of what passes in reveries; and the surprise + on recovering from them, are explained in Section <a + href="#sect_XVIII_19">XVIII. 19</a>. and in Section <a + href="#sect_XVII_3_7">XVII. 3. 7</a>.</p> + + <p><a name="sect_XIX_9">9</a>. It appears from hence, that reverie is a + disease of the epileptic or cataleptic kind, since the paroxysms of this + young lady always began and frequently terminated with convulsions; and + though in its greatest degree it has been called somnambulation, or + sleep-walking, it is totally different from sleep; because the essential + character of sleep consists in the total suspension of volition, which in + reverie is not affected; and the essential character of reverie consists + not in the absence of those irritative motions of our senses, which are + occasioned by the stimulus of external objects, but in their never being + productive of sensation. So that during a fit of reverie that strange + event happens to the whole system of nerves, which occurs only to some + particular branches of them in those, who are a second time exposed to + the action of contagious matter. If the matter of the small-pox be + inserted into the arm of one, who has previously had that disease, it + will stimulate the wound, but the general sensation or inflammation of + the system does not follow, which constitutes the disease. See Sect. <a + href="#sect_XII_3_6">XII. 3. 6</a>. <a href="#sect_XXXIII_2_8">XXXIII. 2. + 8</a>.</p> + + <p><a name="sect_XIX_10">10</a>. The following is the definition or + character of complete reverie. 1. The irritative motions occasioned by + internal stimuli continue, those from the stimuli of external objects are + either not produced at all, or are never succeeded by sensation or + attention, unless they are at the same time excited by volition. 2. The + sensitive motions continue, and are kept consistent by the power of + volition. 3. The voluntary motions continue undisturbed. 4. The associate + motions continue undisturbed.</p> + + <p>Two other cases of reverie are related in Section <a + href="#sect_XXXIV_3">XXXIV. 3</a>. which further evince, that reverie is + an effort of the mind to relieve some painful sensation, and is hence + allied to convulsion, and to insanity. Another case is related in Class + III. 1. 2. 2.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XX">XX</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF VERTIGO.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XX_1">1</a>. <i>We determine our perpendicularity by + the apparent motions of objects. A person hood-winked cannot walk in a + straight line. Dizziness in looking from a tower, in a room stained with + uniform lozenges, on riding over snow.</i> <a href="#sect_XX_2">2</a>. + <i>Dizziness from moving objects. A whirling-wheel. Fluctuations of a + river. Experiment with a child.</i> <a href="#sect_XX_3">3</a>. + <i>Dizziness from our own motions and those of other objects.</i> <a + href="#sect_XX_4">4</a>. <i>Riding over a broad stream. Sea-sickness.</i> + <a href="#sect_XX_5">5</a>. <i>Of turning round on one foot. Dervises in + Turkey. Attention of the mind prevents slight sea-sickness. After a + voyage ideas of vibratory motions are still perceived on shore.</i> <a + href="#sect_XX_6">6</a>. <i>Ideas continue some time after they are + excited. Circumstances of turning on one foot, standing on a tower, and + walking in the dark, explained.</i> <a href="#sect_XX_7">7</a>. + <i>Irritative ideas of apparent motions. Irritative ideas of sounds. + Battèment of the sound of bells and organ-pipes. Vertiginous noise in the + head. Irritative motions of the stomach, intestines, and glands.</i> <a + href="#sect_XX_8">8</a>. <i>Symptoms that accompany vertigo. Why vomiting + comes on in strokes of the palsy. By the motion of a ship. By injuries on + the head. Why motion makes sick people vomit.</i> <a + href="#sect_XX_9">9</a>. <i>Why drunken people are vertiginous. Why a + stone in the ureter, or bile-duct, produces vomiting.</i> <a + href="#sect_XX_10">10</a>. <i>Why after a voyage ideas of vibratory + motions are perceived on shore.</i> <a href="#sect_XX_11">11</a>. + <i>Kinds of vertigo and their cure.</i> <a href="#sect_XX_12">12</a>. + <i>Definition of vertigo.</i></p> + +</blockquote> + + <p><a name="sect_XX_1">1</a>. In learning to walk we judge of the + distances of the objects, which we approach, by the eye; and by observing + their perpendicularity determine our own. This circumstance not having + been attended to by the writers on vision, the disease called vertigo or + dizziness has been little understood.</p> + + <p>When any person loses the power of muscular action, whether he is + erect or in a sitting posture, he sinks down upon the ground; as is seen + in fainting fits, and other instances of great debility. Hence it + follows, that some exertion of muscular power is necessary to preserve + our perpendicular attitude. This is performed by proportionally exerting + the antagonist muscles of the trunk, neck, and limbs; and if at any time + in our locomotions we find ourselves inclining to one side, we either + restore our equilibrium by the efforts of the muscles on the other side, + or by moving one of our feet extend the base, which we rest upon, to the + new center of gravity.</p> + + <p>But the most easy and habitual manner of determining our want of + perpendicularity, is by attending to the apparent motion of the objects + within the sphere of distinct vision; for this apparent motion of + objects, when we incline from our perpendicularity, or begin to fall, is + as much greater than the real motion of the eye, as the diameter of the + sphere of distinct vision is to our perpendicular height.</p> + + <p>Hence no one, who is hood-winked, can walk in a straight line for a + hundred steps together; for he inclines so greatly, before he is warned + of his want of perpendicularity by the sense of touch, not having the + apparent motions of ambient objects to measure this inclination by, that + he is necessitated to move one of his feet outwards, to the right or to + the left, to support the new centre of gravity, and thus errs from the + line he endeavours to proceed in.</p> + + <p>For the same reason many people become dizzy, when they look from the + summit of a tower, which is raised much above all other objects, as these + objects are out of the sphere of distinct vision, and they are obliged to + balance their bodies by the less accurate feelings of their muscles.</p> + + <p>There is another curious phenomenon belonging to this place, if the + circumjacent visible objects are so small, that we do not distinguish + their minute parts; or so similar, that we do not know them from each + other; we cannot determine our perpendicularity by them. Thus in a room + hung with a paper, which is coloured over with similar small black + lozenges or rhomboids, many people become dizzy; for when they begin to + fall, the next and the next lozenge succeeds upon the eye; which they + mistake for the first, and are not aware, that they have any apparent + motion. But if you fix a sheet of paper, or draw any other figure, in the + midst of these lozenges, the charm ceases, and no dizziness is + perceptible.—The same occurs, when we ride over a plain covered + with snow without trees or other eminent objects.</p> + + <p><a name="sect_XX_2">2</a>. But after having compared visible objects + at rest with the sense of touch, and learnt to distinguish their shapes + and shades, and to measure our want of perpendicularity by their apparent + motions, we come to consider them in real motion. Here a new difficulty + occurs, and we require some experience to learn the peculiar mode of + motion of any moving objects, before we can make use of them for the + purposes of determining our perpendicularity. Thus some people become + dizzy at the sight of a whirling wheel, or by gazing on the fluctuations + of a river, if no steady objects are at the same time within the sphere + of their distinct vision; and when a child first can stand erect upon his + legs, if you gain his attention to a white handkerchief steadily extended + like a sail, and afterwards make it undulate, he instantly loses his + perpendicularity, and tumbles on the ground.</p> + + <p><a name="sect_XX_3">3</a>. A second difficulty we have to encounter is + to distinguish our own real movements from the apparent motions of + objects. Our daily practice of walking and riding on horseback soon + instructs us with accuracy to discern these modes of motion, and to + ascribe the apparent motions of the ambient objects to ourselves; but + those, which we have not acquired by repeated habit, continue to confound + us. So as we ride on horseback the trees and cottages, which occur to us, + appear at rest; we can measure their distances with our eye, and regulate + our attitude by them; yet if we carelessly attend to distant hills or + woods through a thin hedge, which is near us, we observe the jumping and + progressive motions of them; as this is increased by the paralax of these + objects; which we have not habituated ourselves to attend to. When first + an European mounts an elephant sixteen feet high, and whose mode of + motion he is not accustomed to, the objects seem to undulate, as he + passes, and he frequently becomes sick and vertiginous, as I am well + informed. Any other unusual movement of our bodies has the same effect, + as riding backwards in a coach, swinging on a rope, turning round swiftly + on one leg, scating on the ice, and a thousand others. So after a patient + has been long confined to his bed, when he first attempts to walk, he + finds himself vertiginous, and is obliged by practice to learn again the + particular modes of the apparent motions of objects, as he walks by + them.</p> + + <p><a name="sect_XX_4">4</a>. A third difficulty, which occurs to us in + learning to balance ourselves by the eye, is, when both ourselves and the + circumjacent objects are in real motion. Here it is necessary, that we + should be habituated to both these modes of motion in order to preserve + our perpendicularity. Thus on horseback we accurately observe another + person, whom we meet, trotting towards us, without confounding his + jumping and progressive motion with our own, because we have been + accustomed to them both; that is, to undergo the one, and to see the + other at the same time. But in riding over a broad and fluctuating + stream, though we are well experienced in the motions of our horse, we + are liable to become dizzy from our inexperience in that of the water. + And when first we go on ship-board, where the movements of ourselves, and + the movements of the large waves are both new to us, the vertigo is + almost unavoidable with the terrible sickness, which attends it. And this + I have been assured has happened to several from being removed from a + large ship into a small one; and again from a small one into a man of + war.</p> + + <p><a name="sect_XX_5">5</a>. From the foregoing examples it is evident, + that, when we are surrounded with unusual motions, we lose our + perpendicularity: but there are some peculiar circumstances attending + this effect of moving objects, which we come now to mention, and shall + hope from the recital of them to gain some insight into the manner of + their production.</p> + + <p>When a child moves round quick upon one foot, the circumjacent objects + become quite indistinct, as their distance increases their apparent + motions; and this great velocity confounds both their forms, and their + colours, as is seen in whirling round a many coloured wheel; he then + loses his usual method of balancing himself by vision, and begins to + stagger, and attempts to recover himself by his muscular feelings. This + staggering adds to the instability of the visible objects by giving a + vibratory motion besides their rotatory one. The child then drops upon + the ground, and the neighbouring objects seem to continue for some + seconds of time to circulate around him, and the earth under him appears + to librate like a balance. In some seconds of time these sensations of a + continuation of the motion of objects vanish; but if he continues turning + round somewhat longer, before he falls, sickness and vomiting are very + liable to succeed. But none of these circumstances affect those who have + habituated themselves to this kind of motion, as the dervises in Turkey, + amongst whom these swift gyrations are a ceremony of religion.</p> + + <p>In an open boat passing from Leith to Kinghorn in Scotland, a sudden + change of the wind shook the undistended sail, and stopt our boat; from + this unusual movement the passengers all vomited except myself. I + observed, that the undulation of the ship, and the instability of all + visible objects, inclined me strongly to be sick; and this continued or + increased, when I closed my eyes, but as often as I bent my attention + with energy on the management and mechanism of the ropes and sails, the + sickness ceased; and recurred again, as often as I relaxed this + attention; and I am assured by a gentleman of observation and veracity, + that he has more than once observed, when the vessel has been in + immediate danger, that the sea-sickness of the passengers has + instantaneously ceased, and recurred again, when the danger was over.</p> + + <p>Those, who have been upon the water in a boat or ship so long, that + they have acquired the necessary habits of motion upon that unstable + element, at their return on land frequently think in their reveries, or + between sleeping and waking, that they observe the room, they sit in, or + some of its furniture, to librate like the motion of the vessel. This I + have experienced myself, and have been told, that after long voyages, it + is some time before these ideas entirely vanish. The same is observable + in a less degree after having travelled some days in a stage coach, and + particularly when we lie down in bed, and compose ourselves to sleep; in + this case it is observable, that the rattling noise of the coach, as well + as the undulatory motion, haunts us. The drunken vertigo, and the vulgar + custom of rocking children, will be considered in the next Section.</p> + + <p><a name="sect_XX_6">6</a>. The motions, which are produced by the + power of volition, may be immediately stopped by the exertion of the same + power on the antagonist muscles; otherwise these with all the other + classes of motion continue to go on, some time after they are excited, as + the palpitation of the heart continues after the object of fear, which + occasioned it, is removed. But this circumstance is in no class of + motions more remarkable than in those dependent on irritation; thus if + any one looks at the sun, and then covers his eyes with his hand, he will + for many seconds of time, perceive the image of the sun marked on his + retina: a similar image of all other visible objects would remain some + time formed on the retina, but is extinguished by the perpetual change of + the motions of this nerve in our attention to other objects. To this must + be added, that the longer time any movements have continued to be excited + without fatigue to the organ, the longer will they continue + spontaneously, after the excitement is withdrawn: as the taste of tobacco + in the mouth after a person has been smoaking it.</p> + + <p>This taste remains so strong, that if a person continues to draw air + through a tobacco pipe in the dark, after having been smoking some time, + he cannot distinguish whether his pipe be lighted or not.</p> + + <p>From these two considerations it appears, that the dizziness felt in + the head, after seeing objects in unusual motion, is no other than a + continuation of the motions of the optic nerve excited by those objects + and which engage our attention. Thus on turning round on one foot, the + vertigo continues for some seconds of time after the person is fallen on + the ground; and the longer he has continued to revolve, the longer will + continue these successive motions of the parts of the optic nerve.</p> + +<blockquote class="b1"> + +<p class="center" style="margin-top: 2em;"><i>Additional Observations on </i>VERTIGO.</p> + + <p>After revolving with your eyes open till you become vertiginous, as + soon as you cease to revolve, not only the circum-ambient objects appear + to circulate round you in a direction contrary to that, in which you have + been turning, but you are liable to roll your eyes forwards and + backwards; as is well observed, and ingeniously demonstrated by Dr. Wells + in a late publication on vision. The same occurs, if you revolve with + your eyes closed, and open them immediately at the time of your ceasing + to turn; and even during the whole time of revolving, as may be felt by + your hand pressed lightly on your closed eyelids. To these movements of + the eyes, of which he supposes the observer to be inconscious, Dr. Wells + ascribes the apparent circumgyration of objects on ceasing to + revolve.</p> + + <p>The cause of thus turning our eyes forwards, and then back again, + after our body is at rest, depends, I imagine, on the same circumstance, + which induces us to follow the indistinct spectra, which are formed on + one side of the center of the retina, when we observe them apparently on + clouds, as described in Sect. <a href="#sect_XL_2_2">XL. 2. 2</a>.; and + then not being able to gain a more distinct vision of them, we turn our + eyes back, and again and again pursue the flying shade.</p> + + <p>But this rolling of the eyes, after revolving till we become + vertiginous, cannot cause the apparent circumgyration of objects, in a + direction contrary to that in which we have been revolving, for the + following reasons. 1. Because in pursuing a spectrum in the sky, or on + the ground, as above mentioned, we perceive no retrograde motions of + objects. 2. Because the apparent retrograde motions of objects, when we + have revolved till we are vertiginous, continues much longer than the + rolling of the eyes above described.</p> + + <p>3. When we have revolved from right to left, the apparent motion of + objects, when we stop, is from left to right; and when we have revolved + from left to right, the apparent circulation of objects is from right to + left; yet in both these cases the eyes of the revolver are seen equally + to roll forwards and backwards.</p> + + <p>4. Because this rolling of the eyes backwards and forwards takes place + during our revolving, as may be perceived by the hand lightly pressed on + the closed eyelids, and therefore exists before the effect ascribed to + it.</p> + + <p>And fifthly, I now come to relate an experiment, in which the rolling + of the eyes does not take place at all after revolving, and yet the + vertigo is more distressing than in the situations above mentioned. If + any one looks steadily at a spot in the ceiling over his head, or indeed + at his own finger held up high over his head, and in that situation turns + round till he becomes giddy; and then stops, and looks horizontally; he + now finds, that the apparent rotation of objects is from above downwards, + or from below upwards; that is, that the apparent circulation of objects + is now vertical instead of horizontal, making part of a circle round the + axis of his <i>eye</i>; and this without any rolling of his eyeballs. The + reason of there being no rolling of the eyeballs, perceived after this + experiment, is, because the images of objects are formed in rotation + round the axis of the eye, and not from one side to the other of the axis + of it; so that, as the eyeball has not power to turn in its socket round + its own axis, it cannot follow the apparent motions of these evanescent + spectra, either before or after the body is at rest. From all which + arguments it is manifest, that these apparent retrograde gyrations of + objects are not caused by the rolling of the eyeballs; first, because no + apparent retrogression of objects is observed in other rollings of the + eyes: secondly, because the apparent retrogression of objects continues + many seconds after the rolling of the eyeballs ceases. Thirdly, because + the apparent retrogression of objects is sometimes one way, and sometimes + another, yet the rolling of the eyeballs is the same. Fourthly, because + the rolling of the eyeballs exists before the apparent retrograde motions + of objects is observed; that is, before the revolving person stops. And + fifthly, because the apparent retrograde gyration of objects is produced, + when there is no rolling of the eyeballs at all.</p> + + <p>Doctor Wells imagines, that no spectra can be gained in the eye, if a + person revolves with his eyelids closed, and thinks this a sufficient + argument against the opinion, that the apparent progression of the + spectra of light or colours in the eye can cause the apparent + retrogression of objects in the vertigo above described; but it is + certain, when any person revolves in a light room with his eyes closed, + that he nevertheless perceives differences of light both in quantity and + colour through his eyelids, as he turns round; and readily gains spectra + of those differences. And these spectra are not very different except in + vivacity from those, which he acquires, when he revolves with unclosed + eyes, since if he then revolves very rapidly the colours and forms of + surrounding objects are as it were mixed together in his eye;. as when, + the prismatic colours are painted on a wheel, they appear white as they + revolve. The truth of this is evinced by the staggering or vertigo of men + perfectly blind, when they turn round; which is not attended with + apparent circulation of objects, but is a vertiginous disorder of the + sense of touch. Blind men balance themselves by their sense of touch; + which, being less adapted for perceiving small deviations from their + perpendicular, occasions them to carry themselves more erect in walking. + This method of balancing themselves by the direction of their pressure + against the floor, becomes disordered by the unusual mode of action in + turning round, and they begin to lose their perpendicularity, that is, + they become vertiginous; but without any apparent circular motions of + visible objects.</p> + + <p>It will appear from the following experiments, that the apparent + progression of the ocular spectra of light or colours is the cause of the + apparent retrogression of objects, after a person has revolved, till he + is vertiginous.</p> + + <p>First, when a person turns round in a light room with his eyes open, + but closes them before he stops, he will seem to be carried forwards in + the direction he was turning for a short time after he stops. But if he + opens his eyes again, the objects before him instantly appear to move in + a retrograde direction, and he loses the sensation of being carried + forwards. The same occurs if a person revolves in a light room with his + eyes closed; when he stops, he seems to be for a time carried forwards, + if his eyes are still closed; but the instant he opens them, the + surrounding objects appear to move in retrograde gyration. From hence it + may be concluded, that it is the sensation or imagination of our + continuing to go forwards in the direction in which we were turning, that + causes the apparent retrograde circulation of objects.</p> + + <p>Secondly, though there is an audible vertigo, as is known by the + battement, or undulations of sound in the ears, which many vertiginous + people experience; and though there is also a tangible vertigo, as when a + blind person turns round, as mentioned above; yet as this circumgyration + of objects is an hallucination or deception of the sense of sight, we are + to look for the cause of our appearing to move forward, when we stop with + our eyes closed after gyration, to some affection of this sense. Now, + thirdly, if the spectra formed in the eye during our rotation, continue + to change, when we stand still, like the spectra described in Sect. <a + href="#sect_III_3_6">III. 3. 6</a>. such changes must suggest to us the + idea or sensation of our still continuing to turn round; as is the case, + when we revolve in a light room, and close our eyes before we stop. And + lastly, on opening our eyes in the situation above described, the objects + we chance to view amid these changing spectra in the eye, must seem to + move in a contrary direction; as the moon sometimes appears to move + retrograde, when swift-gliding clouds are passing forwards so much nearer + the eye of the beholder.</p> + + <p>To make observations on faint ocular spectra requires some degree of + habit, and composure of mind, and even patience; some of those described + in Sect. <a href="#sect_XL">XL</a>. were found difficult to see, by many, + who tried them; now it happens, that the mind, during the confusion of + vertigo, when all the other irritative tribes of motion, as well as those + of vision, are in some degree disturbed, together with the fear of + falling, is in a very unfit state for the contemplation of such weak + sensations, as are occasioned by faint ocular spectra. Yet after + frequently revolving, both with my eyes closed, and with them open, and + attending to the spectra remaining in them, by shading the light from my + eyelids more or less with my hand, I at length ceased to have the idea of + going forward, after I stopped with my eyes closed; and saw changing + spectra in my eyes, which seemed to move, as it were, over the field of + vision; till at length, by repeated trials on sunny days, I persuaded + myself, on opening my eyes, after revolving some time, on a shelf of + gilded books in my library, that I could perceive the spectra in my eyes + move forwards over one or two of the books, like the vapours in the air + of a summer's day; and could so far undeceive myself, as to perceive the + books to stand still. After more trials I sometimes brought myself to + believe, that I saw changing spectra of lights and shades moving in my + eyes, after turning round for some time, but did not imagine either the + spectra or the objects to be in a state of gyration. I speak, however, + with diffidence of these facts, as I could not always make the + experiments succeed, when there was not a strong light in my room, or + when my eyes were not in the most proper state for such observations.</p> + + <p>The ingenious and learned M. Sauvage has mentioned other theories to + account for the apparent circumgyration of objects in vertiginous people. + As the retrograde motions of the particles of blood in the optic + arteries, by spasm, or by fear, as is seen in the tails of tadpoles, and + membranes between the fingers of frogs. Another cause he thinks may be + from the librations to one side, and to the other, of the crystalline + lens in the eye, by means of involuntary actions of the muscles, which + constitute the ciliary process. Both these theories lie under the same + objection as that of Dr. Wells before mentioned; namely, that the + apparent motions of objects, after the observer has revolved for some + time, should appear to vibrate this way and that; and not to circulate + uniformly in a direction contrary to that, in which the observer had + revolved.</p> + + <p>M. Sauvage has, lastly, mentioned the theory of colours left in the + eye, which he has termed impressions on the retina. He says, "Experience + teaches us, that impressions made on the retina by a visible object + remain some seconds after the object is removed; as appears from the + circle of fire which we see, when a fire-stick is whirled round in the + dark; therefore when we are carried round our own axis in a circle, we + undergo a temporary vertigo, when we stop; because the impressions of the + circumjacent objects remain for a time afterwards on the retina." + Nosolog. Method. Clas. VIII. I. 1. We have before observed, that the + changes of these colours remaining in the eye, evinces them to be motions + of the fine terminations of the retina, and not impressions on it; as + impressions on a passive substance must either remain, or cease intirely. + See an additional note at the end of the second volume.</p> + +</blockquote> + + <p>Any one, who stands alone on the top of a high tower, if he has not + been accustomed to balance himself by objects placed at such distances + and with such inclinations, begins to stagger, and endeavours to recover + himself by his muscular feelings. During this time the apparent motion of + objects at a distance below him is very great, and the spectra of these + apparent motions continue a little time after he has experienced them; + and he is persuaded to incline the contrary way to counteract their + effects; and either immediately falls, or applying his hands to the + building, uses his muscular feelings to preserve his perpendicular + attitude, contrary to the erroneous persuasions of his eyes. Whilst the + person, who walks in the dark, staggers, but without dizziness; for he + neither has the sensation of moving objects to take off his attention + from his muscular feelings, nor has he the spectra of those motions + continued on his retina to add to his confusion. It happens indeed + sometimes to one landing on a tower, that the idea of his not having room + to extend his base by moving one of his feet outwards, when he begins to + incline, superadds fears to his other inconveniences; which like + surprise, joy, or any great degree of sensation, enervates him in a + moment, by employing the whole sensorial power, and by thus breaking all + the associated trains and tribes of motion.</p> + + <p><a name="sect_XX_7">7</a>. The irritative ideas of objects, whilst we + are awake, are perpetually present to our sense of sight; as we view the + furniture of our rooms, or the ground, we tread upon, throughout the + whole day without attending to it. And as our bodies are never at perfect + rest during our waking hours, these irritative ideas of objects are + attended perpetually with irritative ideas of their apparent motions. The + ideas of apparent motions are always irritative ideas, because we never + attend to them, whether we attend to the objects themselves, or to their + real motions, or to neither. Hence the ideas of the apparent motions of + objects are a complete circle of irritative ideas, which continue + throughout the day.</p> + + <p>Also during all our waking hours, there is a perpetual confused sound + of various bodies, as of the wind in our rooms, the fire, distant + conversations, mechanic business; this continued buzz, as we are seldom + quite motionless, changes its loudness perpetually, like the sound of a + bell; which rises and falls as long as it continues, and seems to pulsate + on the ear. This any one may experience by turning himself round near a + waterfall; or by striking a glass bell, and then moving the direction of + its mouth towards the ears, or from them, as long as its vibrations + continue. Hence this undulation of indistinct sound makes another + concomitant circle of irritative ideas, which continues throughout the + day.</p> + + <p>We hear this undulating sound, when we are perfectly at rest + ourselves, from other sonorous bodies besides bells; as from two + organ-pipes, which are nearly but not quite in unison, when they are + sounded together. When a bell is struck, the circular form is changed + into an eliptic one; the longest axis of which, as the vibrations + continue, moves round the periphery of the bell; and when either axis of + this elipse is pointed towards our ears, the sound is louder; and less + when the intermediate parts of the elipse are opposite to us. The + vibrations of the two organ-pipes may be compared to Nonius's rule; the + sound is louder, when they coincide, and less at the intermediate times. + But, as the sound of bells is the most familiar of those sounds, which + have a considerable battement, the vertiginous patients, who attend to + the irritative circles of sounds above described, generally compare it to + the noise of bells.</p> + + <p>The peristaltic motions of our stomach and intestines, and the + secretions of the various glands, are other circles of irritative + motions, some of them more or less complete, according to our abstinence + or satiety.</p> + + <p>So that the irritative ideas of the apparent motions of objects, the + irritative battements of sounds, and the movements of our bowels and + glands compose a great circle of irritative tribes of motion: and when + one considerable part of this circle of motions becomes interrupted, the + whole proceeds in confusion, as described in Section <a + href="#sect_XVII_1_7">XVII. 1. 7</a>. on Catenation of Motions.</p> + + <p><a name="sect_XX_8">8</a>. Hence a violent vertigo, from whatever + cause it happens, is generally attended with undulating noise in the + head, perversions of the motions of the stomach and duodenum, unusual + excretion of bile and gastric juice, with much pale urine, sometimes with + yellowness of the skin, and a disordered secretion of almost every gland + of the body, till at length the arterial system is affected, and fever + succeeds.</p> + + <p>Thus bilious vomitings accompany the vertigo occasioned by the motion + of a ship; and when the brain is rendered vertiginous by a paralytic + affection of any part of the body, a vomiting generally ensues, and a + great discharge of bile: and hence great injuries of the head from + external violence are succeeded with bilious vomitings, and sometimes + with abscesses of the liver. And hence, when a patient is inclined to + vomit from other causes, as in some fevers, any motions of the attendants + in his room, or of himself when he is raised or turned in his bed, + presently induces the vomiting by superadding a degree of vertigo.</p> + + <p><a name="sect_XX_9">9</a>. And conversely it is very usual with those, + whose stomachs are affected from internal causes, to be afflicted with + vertigo, and noise in the head; such is the vertigo of drunken people, + which continues, when their eyes are closed, and themselves in a + recumbent posture, as well as when they are in an erect posture, and have + their eyes open. And thus the irritation of a stone in the bile-duct, or + in the ureter, or an inflammation of any of the intestines, are + accompanied with vomitings and vertigo.</p> + + <p>In these cases the irritative motions of the stomach, which are in + general not attended to, become so changed by some unnatural stimulus, as + to become uneasy, and excite our sensation or attention. And thus the + other irritative trains of motions, which are associated with it, become + disordered by their sympathy. The same happens, when a piece of gravel + sticks in the ureter, or when some part of the intestinal canal becomes + inflamed. In these cases the irritative muscular motions are first + disturbed by unusual stimulus, and a disordered action of the sensual + motions, or dizziness ensues. While in sea-sickness the irritative + sensual motions, as vertigo, precedes; and the disordered irritative + muscular motions, as those of the stomach in vomiting, follow.</p> + + <p><a name="sect_XX_10">10</a>. When these irritative motions are + disturbed, if the degree be not very great, the exertion of voluntary + attention to any other object, or any sudden sensation, will disjoin + these new habits of motion. Thus some drunken people have become sober + immediately, when any accident has strongly excited their attention; and + sea-sickness has vanished, when the ship has been in danger. Hence when + our attention to other objects is most relaxed, as just before we fall + asleep, or between our reveries when awake, these irritative ideas of + motion and sound are most liable to be perceived; as those, who have been + at sea, or have travelled long in a coach, seem to perceive the + vibrations of the ship, or the rattling of the wheels, at these + intervals; which cease again, as soon as they exert their attention. That + is, at those intervals they attend to the apparent motions, and to the + battement of sounds of the bodies around them, and for a moment mistake + them for those real motions of the ship, and noise of wheels, which they + had lately been accustomed to: or at these intervals of reverie, or on + the approach of sleep, these supposed motions or sounds may be produced + entirely by imagination.</p> + + <p>We may conclude from this account of vertigo, that sea-sickness is not + an effort of nature to relieve herself, but a necessary consequence of + the associations or catenations of animal motions. And may thence infer, + that the vomiting, which attends the gravel in the ureter, inflammations + of the bowels, and the commencement of some fevers, has a similar origin, + and is not always an effort of the vis medicatrix naturæ. But where the + action of the organ is the immediate consequence of the stimulating + cause, it is frequently exerted to dislodge that stimulus, as in vomiting + up an emetic drug; at other times, the action of an organ is a general + effort to relieve pain, as in convulsions of the locomotive muscles; + other actions drink up and carry on the fluids, as in absorption and + secretion; all which may be termed efforts of nature to relieve, or to + preserve herself.</p> + + <p><a name="sect_XX_11">11</a>. The cure of vertigo will frequently + depend on our previously investigating the cause of it, which from what + has been delivered above may originate from the disorder of any part of + the great tribes of irritative motions, and of the associate motions + catenated with them.</p> + + <p>Many people, when they arrive at fifty or sixty years of age, are + affected with slight vertigo; which is generally but wrongly ascribed to + indigestion, but in reality arises from a beginning defect of their + sight; as about this time they also find it necessary to begin to use + spectacles, when they read small prints, especially in winter, or by + candle light, but are yet able to read without them during the summer + days, when the light is stronger. These people do not see objects so + distinctly as formerly, and by exerting their eyes more than usual, they + perceive the apparent motions of objects, and confound them with the real + motions of them; and therefore cannot accurately balance themselves so as + easily to preserve their perpendicularity by them.</p> + + <p>That is, the apparent motions of objects, which are at rest, as we + move by them, should only excite irritative ideas: but as these are now + become less distinct, owing to the beginning imperfection of our sight, + we are induced <i>voluntarily</i> to attend to them; and then these + apparent motions become succeeded by sensation; and thus the other parts + of the trains of irritative ideas, or irritative muscular motions, become + disordered, as explained above. In these cases of slight vertigo I have + always promised my patients, that they would get free from it in two or + three months, as they should acquire the habit of balancing their bodies + by less distinct objects, and have seldom been mistaken in my + prognostic.</p> + + <p>There is an auditory vertigo, which is called a noise in the head, + explained in No. <a href="#sect_XX_7">7</a>. of this section, which also + is very liable to affect people in the advance of life, and is owing to + their hearing less perfectly than before. This is sometimes called a + ringing, and sometimes a singing, or buzzing, in the ears, and is + occasioned by our first experiencing a disagreeable sensation from our + not being able distinctly to hear the sounds, we used formerly to hear + distinctly. And this disagreeable sensation excites desire and consequent + volition; and when we voluntarily attend to small indistinct sounds, even + the whispering of the air in a room, and the pulsations of the arteries + of the ear are succeeded by sensation; which minute sounds ought only to + have produced irritative sensual motions, or unperceived ideas. See + Section <a href="#sect_XVII_3_6">XVII. 3. 6</a>. These patients after a + while lose this auditory vertigo, by acquiring a new habit of not + attending voluntarily to these indistinct sounds, but contenting + themselves with the less accuracy of their sense of hearing.</p> + + <p>Another kind of vertigo begins with the disordered action of some + irritative muscular motions, as those of the stomach from intoxication, + or from emetics; or those of the ureter, from the stimulus of a stone + lodged in it; and it is probable, that the disordered motions of some of + the great congeries of glands, as of those which form the liver, or of + the intestinal canal, may occasion vertigo in consequence of their + motions being associated or catenated with the great circles of + irritative motions; and from hence it appears, that the means of cure + must be adapted to the cause.</p> + + <p>To prevent sea-sickness it is probable, that the habit of swinging for + a week or two before going on shipboard might be of service. For the + vertigo from failure of sight, spectacles may be used. For the auditory + vertigo, æther may be dropt into the ear to stimulate the part, or to + dissolve ear-wax, if such be a part of the cause. For the vertigo arising + from indigestion, the peruvian bark and a blister are recommended. And + for that owing to a stone in the ureter, venesection, cathartics, + opiates, sal soda aerated.</p> + + <p><a name="sect_XX_12">12</a>. Definition of vertigo. 1. Some of the + irritative sensual, or muscular motions, which were usually not succeeded + by sensation, are in this disease succeeded by sensation; and the trains + or circles of motions, which were usually catenated with them, are + interrupted, or inverted, or proceed in confusion. 2. The sensitive and + voluntary motions continue undisturbed. 3. The associate trains or + circles of motions continue; but their catenations with some of the + irritative motions are disordered, or inverted, or dissevered.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXI">XXI</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF DRUNKENNESS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXI_1">1</a>. <i>Sleep from satiety of hunger. From + rocking children. From uniform sounds.</i> <a href="#sect_XXI_2">2</a>. + <i>Intoxication from common food after fatigue and inanition.</i> <a + href="#sect_XXI_3">3</a>. <i>From wine or of opium. Chilness after meals. + Vertigo. Why pleasure is produced by intoxication, and by swinging and + rocking children. And why pain is relieved by it.</i> <a + href="#sect_XXI_4">4</a>. <i>Why drunkards stagger and stammer, and are + liable to weep.</i> <a href="#sect_XXI_5">5</a>. <i>And become delirious, + sleepy, and stupid.</i> <a href="#sect_XXI_6">6</a>. <i>Or make pale + urine and vomit.</i> <a href="#sect_XXI_7">7</a>. <i>Objects are seen + double.</i> <a href="#sect_XXI_8">8</a>. <i>Attention of the mind + diminishes drunkenness.</i> <a href="#sect_XXI_9">9</a>. <i>Disordered + irritative motions of all the senses.</i> <a href="#sect_XXI_10">10</a>. + <i>Diseases from drunkenness.</i> <a href="#sect_XXI_11">11</a>. + <i>Definition of drunkenness.</i></p> + +</blockquote> + + <p><a name="sect_XXI_1">1</a>. In the state of nature when the sense of + hunger is appeased by the stimulus of agreeable food, the business of the + day is over, and the human savage is at peace with the world, he then + exerts little attention to external objects, pleasing reveries of + imagination succeed, and at length sleep is the result: till the + nourishment which he has procured, is carried over every part of the + system to repair the injuries of action, and he awakens with fresh + vigour, and feels a renewal of his sense of hunger.</p> + + <p>The juices of some bitter vegetables, as of the poppy and the + laurocerasus, and the ardent spirit produced in the fermentation of the + sugar found in vegetable juices, are so agreeable to the nerves of the + stomach, that, taken in a small quantity, they instantly pacify the sense + of hunger; and the inattention to external stimuli with the reveries of + imagination, and sleep, succeeds, in the same manner as when the stomach + is filled with other less intoxicating food.</p> + + <p>This inattention to the irritative motions occasioned by external + stimuli is a very important circumstance in the approach of sleep, and is + produced in young children by rocking their cradles: during which all + visible objects become indistinct to them. An uniform soft repeated + sound, as the murmurs of a gentle current, or of bees, are said to + produce the same effect, by presenting indistinct ideas of + inconsequential sounds, and by thus stealing our attention from other + objects, whilst by their continued reiterations they become familiar + themselves, and we cease gradually to attend to any thing, and sleep + ensues.</p> + + <p><a name="sect_XXI_2">2</a>. After great fatigue or inanition, when the + stomach is suddenly filled with flesh and vegetable food, the inattention + to external stimuli, and the reveries of imagination, become so + conspicuous as to amount to a degree of intoxication. The same is at any + time produced by superadding a little wine or opium to our common meals; + or by taking these separately in considerable quantity; and this more + efficaciously after fatigue or inanition; because a less quantity of any + stimulating material will excite an organ into energetic action, after it + has lately been torpid from defect of stimulus; as objects appear more + luminous, after we have been in the dark; and because the suspension of + volition, which is the immediate cause of sleep, is sooner induced, after + a continued voluntary exertion has in part exhausted the sensorial power + of volition; in the same manner as we cannot contract a single muscle + long together without intervals of inaction.</p> + + <p><a name="sect_XXI_3">3</a>. In the beginning of intoxication we are + inclined to sleep, as mentioned above, but by the excitement of external + circumstances, as of noise, light, business, or by the exertion of + volition, we prevent the approaches of it, and continue to take into our + stomach greater quantities of the inebriating materials. By these means + the irritative movements of the stomach are excited into greater action + than is natural; and in consequence all the irritative tribes and trains + of motion, which are catenated with them, become susceptible of stronger + action from their accustomed stimuli; because these motions are excited + both by their usual irritation, and by their association with the + increased actions of the stomach and lacteals. Hence the skin glows, and + the heat of the body is increased, by the more energetic action of the + whole glandular system; and pleasure is introduced in consequence of + these increased motions from internal stimulus. According to Law 5. Sect. + <a href="#sect_IV">IV</a>. on Animal Causation.</p> + + <p>From this great increase of irritative motions from internal stimulus, + and the increased sensation introduced into the system in consequence; + and secondly, from the increased sensitive motions in consequence of this + additional quantity of sensation, so much sensorial power is expended, + that the voluntary power becomes feebly exerted, and the irritation from + the stimulus of external objects is less forcible; the external parts of + the eye are not therefore voluntarily adapted to the distances of + objects, whence the apparent motions of those objects either are seen + double, or become too indistinct for the purpose of balancing the body, + and vertigo is induced.</p> + + <p>Hence we become acquainted with that very curious circumstance, why + the drunken vertigo is attended with an increase of pleasure; for the + irritative ideas and motions occasioned by internal stimulus, that were + not attended to in our sober hours, are now just so much increased as to + be succeeded by pleasurable sensation, in the same manner as the more + violent motions of our organs are succeeded by painful sensation. And + hence a greater quantity of pleasurable sensation is introduced into the + constitution; which is attended in some people with an increase of + benevolence and good humour.</p> + + <p>If the apparent motions of objects is much increased, as when we + revolve on one foot, or are swung on a rope, the ideas of these apparent + motions are also attended to, and are succeeded with pleasureable + sensation, till they become familiar to us by frequent use. Hence + children are at first delighted with these kinds of exercise, and with + riding, and failing, and hence rocking young children inclines them to + sleep. For though in the vertigo from intoxication the irritative ideas + of the apparent motions of objects are indistinct from their decrease of + energy: yet in the vertigo occasioned by rocking or swinging the + irritative ideas of the apparent motions of objects are increased in + energy, and hence they induce pleasure into the system, but are equally + indistinct, and in consequence equally unfit to balance ourselves by. + This addition of pleasure precludes desire or aversion, and in + consequence the voluntary power is feebly exerted, and on this account + rocking young children inclines them to sleep.</p> + + <p>In what manner opium and wine act in relieving pain is another + article, that well deserves our attention. There are many pains that + originate from defect as well as from excess of stimulus; of these are + those of the six appetites of hunger, thirst, lust, the want of heat, of + distention, and of fresh air. Thus if our cutaneous capillaries cease to + act from the diminished stimulus of heat, when we are exposed to cold + weather, or our stomach is uneasy for want of food; these are both pains + from defect of stimulus, and in consequence opium, which stimulates all + the moving system into increased action, must relieve them. But this is + not the case in those pains, which arise from excess of stimulus, as in + violent inflammations: in these the exhibition of opium is frequently + injurious by increasing the action of the system already too great, as in + inflammation of the bowels mortification is often produced by the + stimulus of opium. Where, however, no such bad consequences follow; the + stimulus of opium, by increasing all the motions of the system, expends + so much of the sensorial power, that the actions of the whole system soon + become feebler, and in consequence those which produced the pain and + inflammation.</p> + + <p><a name="sect_XXI_4">4</a>. When intoxication proceeds a little + further, the quantity of pleasurable sensation is so far increased, that + all desire ceases, for there is no pain in the system to excite it. Hence + the voluntary exertions are diminished, staggering and stammering + succeed; and the trains of ideas become more and more inconsistent from + this defect of voluntary exertion, as explained in the sections on sleep + and reverie, whilst those passions which are unmixed with volition are + more vividly felt, and shewn with less reserve; hence pining love, or + superstitious fear, and the maudling tear dropped on the remembrance of + the most trifling distress.</p> + + <p><a name="sect_XXI_5">5</a>. At length all these circumstances are + increased; the quantity of pleasure introduced into the system by the + increased irritative muscular motions of the whole sanguiferous, and + glandular, and absorbent systems, becomes so great, that the organs of + sense are more forcibly excited into action by this internal pleasurable + sensation, than by the irritation from the stimulus of external objects. + Hence the drunkard ceases to attend to external stimuli, and as volition + is now also suspended, the trains of his ideas become totally + inconsistent as in dreams, or delirium: and at length a stupor succeeds + from the great exhaustion of sensorial power, which probably does not + even admit of dreams, and in which, as in apoplexy, no motions continue + but those from internal stimuli, from sensation, and from + association.</p> + + <p><a name="sect_XXI_6">6</a>. In other people a paroxysm of drunkenness + has another termination; the inebriate, as soon as he begins to be + vertiginous, makes pale urine in great quantities and very frequently, + and at length becomes sick, vomits repeatedly, or purges, or has profuse + sweats, and a temporary fever ensues with a quick strong pulse. This in + some hours is succeeded by sleep; but the unfortunate bacchanalian does + not perfectly recover himself till about the same time of the succeeding + day, when his course of inebriation began. As shewn in Sect. <a + href="#sect_XVII_1_7">XVII. 1. 7</a>. on Catenation. The temporary fever + with strong pulse is owing to the same cause as the glow on the skin + mentioned in the third paragraph of this Section: the flow of urine and + sickness arises from the whole system of irritative motions being thrown + into confusion by their associations with each other; as in sea-sickness, + mentioned in Sect. <a href="#sect_XX_4">XX. 4</a>. on Vertigo; and which + is more fully explained in Section <a href="#sect_XXIX">XXIX</a>. on + Diabetes.</p> + + <p><a name="sect_XXI_7">7</a>. In this vertigo from internal causes we + see objects double, as two candles instead of one, which is thus + explained. Two lines drawn through the axes of our two eyes meet at the + object we attend to: this angle of the optic axes increases or diminishes + with the less or greater distances of objects. All objects before or + behind the place where this angle is formed, appear double; as any one + may observe by holding up a pen between his eyes and the candle; when he + looks attentively at a spot on the pen, and carelessly at the candle, it + will appear double; and the reverse when he looks attentively at the + candle and carelessly at the pen; so that in this case the muscles of the + eye, like those of the limbs, stagger and are disobedient to the expiring + efforts of volition. Numerous objects are indeed sometimes seen by the + inebriate, occasioned by the refractions made by the tears, which stand + upon his eye-lids.</p> + + <p><a name="sect_XXI_8">8</a>. This vertigo also continues, when the + inebriate lies in his bed, in the dark, or with his eyes closed; and this + more powerfully than when he is erect, and in the light. For the + irritative ideas of the apparent motions of objects are now excited by + irritation from internal stimulus, or by association with other + irritative motions; and the inebriate, like one in a dream, believes the + objects of these irritative motions to be present, and feels himself + vertiginous. I have observed in this situation, so long as my eyes and + mind were intent upon a book, the sickness and vertigo ceased, and were + renewed again the moment I discontinued this attention; as was explained + in the preceding account of sea-sickness. Some drunken people have been + known to become sober instantly from some accident, that has strongly + excited their attention, as the pain of a broken bone, or the news of + their house being on fire.</p> + + <p><a name="sect_XXI_9">9</a>. Sometimes the vertigo from internal + causes, as from intoxication, or at the beginning of some fevers, becomes + so universal, that the irritative motions which belong to other organs of + sense are succeeded by sensation or attention, as well as those of the + eye. The vertiginous noise in the ears has been explained in Section <a + href="#sect_XX">XX</a>. on Vertigo. The taste of the saliva, which in + general is not attended to, becomes perceptible, and the patients + complain of a bad taste in their mouth.</p> + + <p>The common smells of the surrounding air sometimes excite the + attention of these patients, and bad smells are complained of, which to + other people are imperceptible. The irritative motions that belong to the + sense of pressure, or of touch, are attended to, and the patient + conceives the bed to librate, and is fearful of falling out of it. The + irritative motions belonging to the senses of distention, and of heat, + like those above mentioned, become attended to at this time: hence we + feel the pulsation 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 last + paragraph, by the irritative ideas belonging to the various senses being + now excited by internal stimuli, or by their associations with other + irritative motions. And that the inebriate, like one in a dream, believes + the external objects, which usually caused these irritative ideas, to be + now present.</p> + + <p><a name="sect_XXI_10">10</a>. The diseases in consequence of frequent + inebriety, or of daily taking much vinous spirit without inebriety, + consist in the paralysis, which is liable to succeed violent stimulation. + Organs, whose actions are associated with others, are frequently more + affected than the organ, which is stimulated into too violent action. See + Sect. <a href="#sect_XXIV_2_8">XXIV. 2. 8</a>. Hence in drunken people it + generally happens, that the secretory vessels of the liver become first + paralytic, and a torpor with consequent gall-stones or schirrus of this + viscus is induced with concomitant jaundice; otherwise it becomes + inflamed in consequence of previous torpor, and this inflammation is + frequently transferred to a more sensible part, which is associated with + it, and produces the gout, or the rosy eruption of the face, or some + other leprous eruption on the head, or arms, or legs. Sometimes the + stomach is first affected, and paralysis of the lacteal system is + induced: whence a total abhorrence from flesh-food, and general + emaciation. In others the lymphatic system is affected with paralysis, + and dropsy is the consequence. In some inebriates the torpor of the liver + produces pain without apparent schirrus, or gall stones, or inflammation, + or consequent gout, and in these epilepsy or insanity are often the + consequence. All which will be more fully treated of in the course of the + work.</p> + + <p>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 spirituous liquors. To this I answer, that I have seen no + person afflicted with the gout, who has not drank freely of fermented + liquor, as wine and water, or small beer; though as the disposition to + all the diseases, which have originated from intoxication, is in some + degree hereditary, a less quantity of spirituous potation will induce the + gout in those, who inherit the disposition from their parents. To which I + must add, that in young people the rheumatism is frequently mistaken for + the gout.</p> + + <p>Spice is seldom taken in such quantity as to do any material injury to + the system, flesh-meats as well as vegetables are the natural diet of + mankind; with these a glutton may be crammed up to the throat, and fed + fat like a stalled ox; but he will not be diseased, unless he adds + spirituous or fermented liquor to his food. This is well known in the + distilleries, where the swine, which are fattened by the spirituous + sediments of barrels, acquire diseased 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 loses the use both of his limbs and of his understanding! He + becomes a temporary idiot, and has a temporary stroke of the palsy! And + though he slowly recovers after some hours, is it not reasonable to + conclude, that a perpetual repetition of so powerful a poison must at + length permanently affect him?—If a person accidentally becomes + intoxicated by eating a few mushrooms of a peculiar kind, a general alarm + is excited, and he is said to be poisoned, and emetics are exhibited; but + so familiarised are we to the intoxication from vinous spirit, that it + occasions laughter rather than alarm.</p> + + <p>There is however considerable danger in too hastily discontinuing the + use of so strong a stimulus, lest the torpor of the system, or paralysis, + should sooner be induced by the omission than by the continuance of this + habit, when unfortunately acquired. A golden rule for determining the + quantity, which may with safety be discontinued, is delivered in Sect. <a + href="#sect_XII_7_8">XII. 7. 8</a>.</p> + + <p><a name="sect_XXI_11">11</a>. Definition of drunkenness. Many of the + irritative motions are much increased in energy by internal + stimulation.</p> + + <p>2. A great additional quantity of pleasurable sensation is occasioned + by this increased exertion of the irritative motions. And many sensitive + motions are produced in consequence of this increased sensation.</p> + + <p>3. The associated trains and tribes of motions, catenated with the + increased irritative and sensitive motions, are disturbed, and proceed in + confusion.</p> + + <p>4. The faculty of volition is gradually impaired, whence proceeds the + instability of locomotion, inaccuracy of perception, and inconsistency of + ideas; and is at length totally suspended, and a temporary apoplexy + succeeds.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXII">XXII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF PROPENSITY TO MOTION, REPETITION AND IMITATION.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXII_1">I</a>. <i>Accumulation of sensorial power in + hemiplagia, in sleep, in cold fit of fever, in the locomotive muscles, in + the organs of sense. Produces propensity to action.</i> <a + href="#sect_XXII_2">II</a>. <i>Repetition by three sensorial powers. In + rhimes and alliterations, in music, dancing, architecture, + landscape-painting, beauty.</i> <a href="#sect_XXII_3">III</a>. <a + href="#sect_XXII_3_1">1</a>. <i>Perception consists in imitation. Four + kinds of imitation.</i> <a href="#sect_XXII_3_2">2</a>. <i>Voluntary. + Dogs taught to dance.</i> <a href="#sect_XXII_3_3">3</a>. <i>Sensitive. + Hence sympathy, and all our virtues. Contagious matter of venereal + ulcers, of hydrophobia, of jail-fever, of small-pox, produced by + imitation, and the sex of the embryon.</i> <a + href="#sect_XXII_3_4">4</a>. <i>Irritative imitation.</i> <a + href="#sect_XXII_3_5">5</a>. <i>Imitations resolvable into + associations.</i></p> + +</blockquote> + + <p><a name="sect_XXII_1">I</a>. <a name="sect_XXII_1_1">1</a>. In the + hemiplagia, when the limbs on one side have lost their power of voluntary + motion, the patient is for many days perpetually employed in moving those + of the other. <a name="sect_XXII_1_2">2</a>. When the voluntary power is + suspended during sleep, there commences a ceaseless flow of sensitive + motions, or ideas of imagination, which compose our dreams. <a + name="sect_XXII_1_3">3</a>. When in the cold fit of an intermittent fever + some parts of the system have for a time continued torpid, and have thus + expended less than their usual expenditure of sensorial power; a hot fit + succeeds, with violent action of those vessels, which had previously been + quiescent. All these are explained from an accumulation of sensorial + power during the inactivity of some part of the system.</p> + + <p>Besides the very great quantity of sensorial power perpetually + produced and expended in moving the arterial, venous, and glandular + systems, with the various organs or digestion, as described in Section <a + href="#sect_XXXII_3_2">XXXII. 3. 2</a>. there is also a constant + expenditure of it by the action of our locomotive muscles and organs of + sense. Thus the thickness of the optic nerves, where they enter the eye, + and the great expansion of the nerves of touch beneath the whole of the + cuticle, evince the great consumption of sensorial power by these senses. + And our perpetual muscular actions in the common offices of life, and in + constantly preserving the perpendicularity of our bodies during the day, + evince a considerable expenditure of the spirit of animation by our + locomotive muscles. It follows, that if the exertion of these organs of + sense and muscles be for a while intermitted, that some quantity of + sensorial power must be accumulated, and a propensity to activity of some + kind ensue from the increased excitability of the system. Whence proceeds + the irksomeness of a continued attitude, and of an indolent life.</p> + + <p>However small this hourly accumulation of the spirit of animation may + be, it produces a propensity to some kind of action; but it nevertheless + requires either desire or aversion, either pleasure or pain, or some + external stimulus, or a previous link of association, to excite the + system into activity; thus it frequently happens, when the mind and body + are so unemployed as not to possess any of the three first kinds of + stimuli, that the last takes place, and consumes the small but perpetual + accumulation of sensorial power. Whence some indolent people repeat the + same verse for hours together, or hum the same tune. Thus the poet:</p> + + <div class="poem"> + <div class="stanza"> + <p>Onward he trudged, not knowing what he sought,</p> + <p>And whistled, as he went, for want of thought.</p> + </div> + </div> + <p><a name="sect_XXII_2">II</a>. The repetitions of motions may be at + first produced either by volition, or by sensation, or by irritation, but + they soon become easier to perform than any other kinds of action, + because they soon become associated together, according to Law the + seventh, Section <a href="#sect_IV">IV</a>. on Animal Causation. And + because their frequency of repetition, if as much sensorial power be + produced during every reiteration as is expended, adds to the facility of + their production.</p> + + <p>If a stimulus be repeated at uniform intervals of time, as described + in Sect. <a href="#sect_XII_3_3">XII. 3. 3</a>. the action, whether of + our muscles or organs of sense, is produced with still greater facility + or energy; because the sensorial power of association, mentioned above, + is combined with the sensorial power of irritation; that is, in common + language, the acquired habit assists the power of the stimulus.</p> + + <p>This not only obtains in the annual, lunar, and diurnal catenations of + animal motions, as explained in Sect. <a href="#sect_XXXVI">XXXVI</a>. + which are thus performed with great facility and energy; but in every + less circle of actions or ideas, as in the burthen of a song, or the + reiterations of a dance. To the facility and distinctness, with which we + hear sounds at repeated intervals, we owe the pleasure, which we receive + from musical time, and from poetic time; as described in Botanic Garden, + P. 2. Interlude 3. And to this the pleasure we receive from the rhimes + and alliterations of modern verification; the source of which without + this key would be difficult to discover. And to this likewise should be + ascribed the beauty of the duplicature in the perfect tense of the Greek + verbs, and of some Latin ones, as tango tetegi, mordeo momordi.</p> + + <p>There is no variety of notes referable to the gamut in the beating of + the drum, yet if it be performed in musical time, it is agreeable to our + ears; and therefore this pleasurable sensation must be owing to the + repetition of the divisions of the sounds at certain intervals of time, + or musical bars. Whether these times or bars are distinguished by a + pause, or by an emphasis, or accent, certain it is, that this distinction + is perpetually repeated; otherwise the ear could not determine instantly, + whether the successions of sound were in common or in triple time. In + common time there is a division between every two crotchets, or other + notes of equivalent time; though the bar in written music is put after + every fourth crotchet, or notes equivalent in time; in triple time the + division or bar is after every three crotchets, or notes equivalent; so + that in common time the repetition recurs more frequently than in triple + time. The grave or heroic verses of the Greek and Latin poets are written + in common time; the French heroic verses, and Mr. Anstie's humorous + verses in his Bath Guide, are written in the same time as the Greek and + Latin verses, but are one bar shorter. The English grave or heroic verses + are measured by triple time, as Mr. Pope's translation of Homer.</p> + + <p>But besides these little circles of musical time, there are the + greater returning periods, and the still more distant choruses, which, + like the rhimes at the ends of verses, owe their beauty to repetition; + that is, to the facility and distinctness with which we perceive sounds, + which we expect to perceive, or have perceived before; or in the language + of this work, to the greater ease and energy with which our organ is + excited by the combined sensorial powers of association and irritation, + than by the latter singly.</p> + + <p>A certain uniformity or repetition of parts enters the very + composition of harmony. Thus two octaves nearest to each other in the + scale commence their vibrations together after every second vibration of + the higher one. And where the first, third, and fifth compose a chord the + vibrations concur or coincide frequently, though less to than in the two + octaves. It is probable that these chords bear some analogy to a mixture + of three alternate colours in the sun's spectrum separated by a + prism.</p> + + <p>The pleasure we receive from a melodious succession of notes referable + to the gamut is derived from another source, viz. to the pandiculation or + counteraction of antagonist fibres. See Botanic Garden, P. 2. Interlude + 3. If to these be added our early associations of agreeable ideas with + certain proportions of sound, I suppose, from these three sources springs + all the delight of music, so celebrated by ancient authors, and so + enthusiastically cultivated at present. See Sect. <a + href="#sect_XVI_10">XVI. No. 10</a>. on Instinct.</p> + + <p>This kind of pleasure arising from repetition, that is from the + facility and distinctness, with which we perceive and understand repeated + sensations, enters into all the agreeable arts; and when it is carried to + excess is termed formality. The art of dancing like that of music depends + for a great part of the pleasure, it affords, on repetition; + architecture, especially the Grecian, consists of one part being a + repetition of another; and hence the beauty of the pyramidal outline in + landscape-painting; where one side of the picture may be said in some + measure to balance the other. So universally does repetition contribute + to our pleasure in the fine arts, that beauty itself has been defined by + some writers to consist in a due combination of uniformity and variety. + See Sect. <a href="#sect_XVI_6">XVI. 6</a>.</p> + + <p><a name="sect_XXII_3">III</a>. <a name="sect_XXII_3_1">1</a>. Man is + termed by Aristotle an imitative animal; this propensity to imitation not + only appears in the actions of children, but in all the customs and + fashions of the world: many thousands tread in the beaten paths of + others, for one who traverses regions of his own discovery. The origin of + this propensity of imitation has not, that I recollect, been deduced from + any known principle; when any action presents itself to the view of a + child, as of whetting a knife, or threading a needle, the parts of this + action in respect of time, motion, figure, is imitated by a part of the + retina of his eye; to perform this action therefore with his hands is + easier to him than to invent any new action, because it consists in + repeating with another set of fibres, viz. with the moving muscles, what + he had just performed by some parts of the retina; just as in dancing we + transfer the times of motion from the actions of the auditory nerves to + the muscles of the limbs. Imitation therefore consists of repetition, + which we have shewn above to be the easiest kind of animal action, and + which we perpetually fall into, when we possess an accumulation of + sensorial power, which is not otherwise called into exertion.</p> + + <p>It has been shewn, that our ideas are configurations of the organs of + sense, produced originally in consequence of the stimulus of external + bodies. And that these ideas, or configurations of the organs of sense, + referable in some property a correspondent property of external matter; + as the parts of the senses of light and of touch, which are excited into + action, resemble in figure the figure of the stimulating body; and + probably also the colour, and the quantity of density, which they + perceive. As explained in Sect. <a href="#sect_XIV_2_2">XIV. 2. 2</a>. + Hence it appears, that our perceptions themselves are copies, that is, + imitations of some properties of external matter; and the propensity to + imitation is thus interwoven with our existence, as it is produced by the + stimuli of external bodies, and is afterwards repeated by our volitions + and sensations, and thus constitutes all the operations of our minds.</p> + + <p><a name="sect_XXII_3_2">2</a>. Imitations resolve themselves into four + kinds, voluntary, sensitive, irritative, and associate. The voluntary + imitations are, when we imitate deliberately the actions of others, + either by mimicry, as in acting a play, or in delineating a flower; or in + the common actions of our lives, as in our dress, cookery, language, + manners, and even in our habits of thinking.</p> + + <p>Not only the greatest part of mankind learn all the common arts of + life by imitating others, but brute animals seem 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 sick, + learn of each other to eat grass; and I suppose, that by making an + artificial dog perform certain tricks, as in dancing on his hinder legs, + a living dog might be easily induced to imitate them; and that the + readiest way of instructing dumb animals is by practising them with + others of the same species, which have already learned the arts we wish + to teach them. The important use of imitation in acquiring natural + language is mentioned in Section <a href="#sect_XVI_7">XVI. 7</a>. and <a + href="#sect_XVI_8">8</a>. on Instinct.</p> + + <p><a name="sect_XXII_3_3">3</a>. The sensitive imitations are the + immediate consequences of pleasure or pain, and these are often produced + even contrary to the efforts of the will. Thus many young men on seeing + cruel surgical operations become sick, and some even feel pain in the + parts of their own bodies, which they see tortured or wounded in others; + that is, they in some measure imitate by the exertions of their own + fibres the violent actions, which they witnessed in those of others. In + this case a double imitation takes place, first the observer imitates + with the extremities of the optic nerve the mangled limbs, which are + present before his eyes; then by a second imitation he excites to violent + action of the fibres of his own limbs as to produce pain in those parts + of his own body, which he saw wounded in another. In these pains produced + by imitation the effect has some similarity to the cause, which + distinguishes them from those produced by association; as the pains of + the teeth, called tooth-edge, which are produced by association with + disagreeable sounds, as explained in Sect. <a href="#sect_XVI_10">XVI. + 10</a>.</p> + + <p>The effect of this powerful agent, imitation, in the moral world, is + mentioned in Sect. <a href="#sect_XVI_7">XVI. 7</a>. as it is the + foundation of all our intellectual sympathies with the pains and + pleasures of others, and is in consequence the source of all our virtues. + For in what consists our sympathy with the miseries, or with the joys, of + our fellow creatures, but in an involuntary excitation of ideas in some + measure similar or imitative of those, which we believe to exist in the + minds of the persons, whom we commiserate or congratulate?</p> + + <p>There are certain concurrent or successive actions of some of the + glands, or other parts of the body, which are possessed of sensation, + which become intelligible from this propensity to imitation. Of these are + the production of matter by the membranes of the fauces, or by the skin, + in consequence of the venereal disease previously affecting the parts of + generation. Since as no fever is excited, and as neither the blood of + such patients, nor even the matter from ulcers of the throat, or from + cutaneous ulcers, will by inoculation produce the venereal disease in + others, as observed by Mr. Hunter, there is reason to conclude, that no + contagious matter is conveyed thither by the blood-vessels, but that a + milder matter is formed by the actions of the fine vessels in those + membranes imitating each other. See Section <a + href="#sect_XXXIII_2_9">XXXIII. 2. 9</a>. In this disease the actions of + these vessels producing ulcers on the throat and skin are imperfect + imitations of those producing chanker, or gonorrhœa; since the + matter produced by them is not infectious, while the imitative actions in + the hydrophobia appear to be perfect resemblances, as they produce a + material equally infectious with the original one, which induced + them.</p> + + <p>The contagion from the bite of a mad dog 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 some degree explicable on the foregoing theory. The infectious + matter does not appear to enter the circulation, as it cannot be traced + along the course of the lymphatics from the wound, nor is there any + swelling of the lymphatic glands, nor does any fever attend, as occurs in + the small-pox, and in many other contagious diseases; yet by some unknown + process the disease is communicated from the wound to the throat, and + that many months after the injury, so as to produce pain and hydrophobia, + with a secretion of infectious saliva of the same kind, as that of the + mad dog, which inflicted the wound.</p> + + <p>This subject is very intricate.—It would appear, that by certain + morbid actions of the salivary glands of the mad dog, a peculiar kind of + saliva is produced; which being instilled into a wound of another animal + stimulates the cutaneous or mucous glands into morbid actions, but which + are ineffectual in respect to the production of a similar contagious + material; but the salivary glands by irritative sympathy are thrown into + similar action, and produce an infectious saliva similar to that + instilled into the wound.</p> + + <p>Though in many contagious fevers a material similar to that which + produced the disease, is thus generated by imitation; yet there are other + infectious materials, which do not thus propagate themselves, but which + seem to act like slow poisons. Of this kind was the contagious matter, + which produced the jail-fever at the assizes at Oxford about a century + ago. Which, though fatal to so many, was not communicated to their nurses + or attendants. In these cases, the imitations of the fine vessels, as + above described, appear to be imperfect, and do not therefore produce a + matter similar to that, which stimulates them; in this circumstance + resembling the venereal matter in ulcers of the throat or skin, according + to the curious discovery of Mr. Hunter above related, who found, by + repeated inoculations, that it would not infect. Hunter on Venereal + Disease, Part vi. ch. 1.</p> + + <p>Another example of morbid imitation is in the production of a great + quantity of contagious matter, as in the inoculated small-pox, from a + small quantity of it inserted into the arm, and probably diffused in the + blood. These particles of contagious matter stimulate the extremities of + the fine arteries of the skin, and cause them to imitate some properties + of those particles of contagious matter, so as to produce a thousandfold + of a similar material. See Sect. <a href="#sect_XXXIII_2_6">XXXIII. 2. + 6</a>. Other instances are mentioned in the Section on Generation, which + shew the probability that the extremities of the seminal glands may + imitate certain ideas of the mind, or actions of the organs of sense, and + thus occasion the male or female sex of the embryon. See Sect. <a + href="#sect_XXXIX_6">XXXIX. 6</a>.</p> + + <p><a name="sect_XXII_3_4">4</a>. We come now to those imitations, which + are not attended with sensation. Of these are all the irritative ideas + already explained, as when the retina of the eye imitates by its action + or configuration the tree or the bench, which I shun in walking past + without attending to them. Other examples of these irritative imitations + are daily observable in common life; thus one yawning person shall set a + whole company a yawning; and some have acquired winking of the eyes or + impediments of speech by imitating their companions without being + conscious of it.</p> + + <p><a name="sect_XXII_3_5">5</a>. Besides the three species of imitations + above described there may be some associate motions, which may imitate + each other in the kind as well as in the quantity of their action; but it + is difficult to distinguish them from the associations of motions treated + of in Section <a href="#sect_XXXV">XXXV</a>. Where the actions of other + persons are imitated there can be no doubt, or where we imitate a + preconceived idea by exertion of our locomotive muscles, as in painting a + dragon; all these imitations may aptly be referred to the sources above + described of the propensity to activity, and the facility of repetition; + at the same time I do not affirm, that all those other apparent sensitive + and irritative imitations may not be resolvable into associations of a + peculiar kind, in which certain distant parts of similar irritability or + sensibility, and which have habitually acted together, may affect each + other exactly with the same kinds of motion; as many parts are known to + sympathise in the quantity of their motions. And that therefore they may + be ultimately resolvable into associations of action, as described in + Sect. <a href="#sect_XXXV">XXXV</a>.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXIII">XXIII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE CIRCULATORY SYSTEM.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXIII_1">I</a>. <i>The heart and arteries have no + antagonist muscles. Veins absorb the blood, propel it forwards, and + distend the heart; contraction of the heart distends the arteries. Vena + portarum.</i> <a href="#sect_XXIII_2">II</a>. <i>Glands which take their + fluids from the blood. With long necks, with short necks.</i> <a + href="#sect_XXIII_3">III</a>. <i>Absorbent system.</i> <a + href="#sect_XXIII_4">IV</a>. <i>Heat given out from glandular secretions. + Blood changes colour in the lungs and in the glands and capillaries.</i> + <a href="#sect_XXIII_5">V</a>. <i>Blood is absorbed by veins, as chyle by + lacteal vessels, otherwise they could not join their streams.</i> <a + href="#sect_XXIII_6">VI</a>. <i>Two kinds of stimulus, agreeable and + disagreeable. Glandular appetency. Glands originally possessed + sensation.</i></p> + +</blockquote> + + <p><a name="sect_XXIII_1">I</a>. We now step forwards to illustrate some + of the phenomena of diseases, and to trace out their most efficacious + methods of cure; and shall commence this subject with a short description + of the circulatory system.</p> + + <p>As the nerves, whose extremities form our various organs of sense and + muscles, are all joined, or communicate, by means of the brain, for the + convenience perhaps of the distribution of a subtile ethereal fluid for + the purpose of motion; so all those vessels of the body, which carry the + grosser fluids for the purposes of nutrition, communicate with each other + by the heart.</p> + + <p>The heart and arteries are hollow muscles, and are therefore indued + with power of contraction in consequence of stimulus, like all other + muscular fibres; but, as they have no antagonist muscles, the cavities of + the vessels, which they form, would remain for ever closed, after they + have contracted themselves, unless some extraneous power be applied to + again distend them. This extraneous power in respect to the heart is the + current of blood, which is perpetually absorbed by the veins from the + various glands and capillaries, and pushed into the heart by a power + probably very similar to that, which raises the sap in vegetables in the + spring, which, according to Dr. Hale's experiment on the stump of a vine, + exerted a force equal to a column of water above twenty feet high. This + force of the current of blood in the veins is partly produced by their + absorbent power, exerted at the beginning of every fine ramification; + which may be conceived to be a mouth absorbing blood, as the mouths of + the lacteals and lymphatics absorb chyle and lymph. And partly by their + intermitted compression by the pulsations of their generally concomitant + arteries; by which the blood is perpetually propelled towards the heart, + as the valves in many veins, and the absorbent mouths in them all, will + not suffer it to return.</p> + + <p>The blood, thus forcibly injected into the chambers of the heart, + distends this combination of hollow muscles; till by the stimulus of + distention they contract themselves; and, pushing forwards the blood into + the arteries, exert sufficient force to overcome in less than a second of + time the vis inertiæ, and perhaps some elasticity, of the very extensive + ramifications of the two great systems of the aortal and pulmonary + arteries. The power necessary to do this in so short a time must be + considerable, and has been variously estimated by different + physiologists.</p> + + <p>The muscular coats of the arterial system are then brought into action + by the stimulus of distention, and propel the blood to the mouths, or + through the convolutions, which precede the secretory apertures of the + various glands and capillaries.</p> + + <p>In the vessels of the liver there is no intervention of the heart; but + the vena portarum, which does the office of an artery, is distended by + the blood poured into it from the mesenteric veins, and is by this + distention stimulated to contract itself, and propel the blood to the + mouths of the numerous glands, which compose that viscus.</p> + + <p><a name="sect_XXIII_2">II</a>. The glandular system of vessels may be + divided into those, which take some fluid from the circulation; and + those, which give something to it. Those, which take their fluid from the + circulation are the various glands, by which the tears, bile, urine, + perspiration, and many other secretions are produced; these glands + probably consist of a mouth to select, a belly to digest, and an + excretory aperture to emit their appropriated fluids; the blood is + conveyed by the power of the heart and arteries to the mouths of these + glands, it is there taken up by the living power of the gland, and + carried forwards to its belly, and excretory aperture, where a part is + separated, and the remainder absorbed by the veins for further + purposes.</p> + + <p>Some of these glands are furnished with long convoluted necks or + tubes, as the seminal ones, which are curiously seen when injected with + quicksilver. Others seem to consist of shorter tubes, as that great + congeries of glands, which constitute the liver, and those of the + kidneys. Some have their excretory apertures opening into reservoirs, as + the urinary and gall-bladders. And others on the external body, as those + which secrete the tears, and perspirable matter.</p> + + <p>Another great system of glands, which have very short necks, are the + capillary vessels; by which the insensible perspiration is secreted on + the skin; and the mucus of various consistences, which lubricates the + interstices of the cellular membrane, of the muscular fibres, and of all + the larger cavities of the body. From the want of a long convolution of + vessels some have doubted, whether these capillaries should be considered + as glands, and have been led to conclude, that the perspirable matter + rather exuded than was secreted. But the fluid of perspiration is not + simple water, though that part of it, which exhales into the air may be + such; for there is another part of it, which in a state of health is + absorbed again; but which, when the absorbents are diseased, remains on + the surface of the skin, in the form of scurf, or indurated mucus. + Another thing, which shews their similitude to other glands, is their + sensibility to certain affections of the mind; as is seen in the deeper + colour of the skin in the blush of shame, or the greater paleness of it + from fear.</p> + + <p><a name="sect_XXIII_3">III</a>. Another series of glandular vessels is + called the absorbent system; these open their mouths into all the + cavities, and upon all those surfaces of the body, where the excretory + apertures of the other glands pour out their fluids. The mouths of the + absorbent system drink up a part or the whole of these fluids, and carry + them forwards by their living power to their respective glands, which are + called conglobate glands. There these fluids undergo some change, before + they pass on into the circulation; but if they are very acrid, the + conglobate gland swells, and sometimes suppurates, as in inoculation of + the small-pox, in the plague, and in venereal absorptions; at other times + the fluid may perhaps continue there, till it undergoes some chemical + change, that renders it less noxious; or, what is more likely, till it is + regurgitated by the retrograde motion of the gland in spontaneous sweats + or diarrhœas, as disagreeing food is vomited from the stomach.</p> + + <p><a name="sect_XXIII_4">IV</a>. As all the fluids, that pass through + these glands, and capillary vessels, undergo a chemical change, acquiring + new combinations, the matter of heat is at the same time given out; this + is apparent, since whatever increases insensible perspiration, increases + the heat of the skin; and when the action of these vessels is much + increased but for a moment, as in blushing, a vivid heat on the skin is + the immediate consequence. So when great bilious secretions, or those of + any other gland, are produced, heat is generated in the part in + proportion to the quantity of the secretion.</p> + + <p>The heat produced on the skin by blushing may be thought by some too + sudden to be pronounced a chemical effect, as the fermentations or new + combinations taking place in a fluid is in general a slower process. Yet + are there many chemical mixtures in which heat is given out as + instantaneously; as in solutions of metals in acids, or in mixtures of + essential oils and acids, as of oil of cloves and acid of nitre. So the + bruised parts of an unripe apple become almost instantaneously sweet; and + if the chemico-animal process of digestion be stopped for but a moment, + as by fear, or even by voluntary eructation, a great quantity of air is + generated, by the fermentation, which instantly succeeds the stop of + digestion. By the experiments of Dr. Hales it appears, that an apple + during fermentation gave up above six hundred times its bulk of air; and + the materials in the stomach are such, and in such a situation, as + immediately to run into fermentation, when digestion is impeded.</p> + + <p>As the blood passes through the small vessels of the lungs, which + connect the pulmonary artery and vein, it undergoes a change of colour + from a dark to a light red; which may be termed a chemical change, as it + is known to be effected by an admixture of oxygene, or vital air; which, + according to a discovery of Dr. Priestley, passes through the moist + membranes, which constitute the sides of these vessels. As the blood + passes through the capillary vessels, and glands, which connect the aorta + and its various branches with their correspondent veins in the + extremities of the body, it again loses the bright red colour, and + undergoes some new combinations in the glands or capillaries, in which + the matter of heat is given out from the secreted fluids. This process + therefore, as well as the process of respiration, has some analogy to + combustion, as the vital air or oxygene seems to become united to some + inflammable base, and the matter of heat escapes from the new acid, which + is thus produced.</p> + + <p><a name="sect_XXIII_5">V</a>. After the blood has passed these glands + and capillaries, and parted with whatever they chose to take from it, the + remainder is received by the veins, which are a set of blood-absorbing + vessels in general corresponding with the ramifications of the arterial + system. At the extremity of the fine convolutions of the glands the + arterial force ceases; this in respect to the capillary vessels, which + unite the extremities of the arteries with the commencement of the veins, + is evident to the eye, on viewing the tail of a tadpole by means of a + solar, or even by a common microscope, for globules of blood are seen to + endeavour to pass, and to return again and again, before they become + absorbed by the mouths of the veins; which returning of these globules + evinces, that the arterial force behind them has ceased. The veins are + furnished with valves like the lymphatic absorbents; and the great trunks + of the veins, and of the lacteals and lymphatics, join together before + the ingress of their fluids into the left chamber of the heart; both + which evince, that the blood in the veins, and the lymph and chyle in the + lacteals and lymphatics, are carried on by a similar force; otherwise the + stream, which was propelled with a less power, could not enter the + vessels, which contained the stream propelled with a greater power. From + whence it appears, that the veins are a system of vessels absorbing + blood, as the lacteals and lymphatics are a system of vessels absorbing + chyle and lymph. See Sect. <a href="#sect_XXVII_1">XXVII. 1</a>.</p> + + <p><a name="sect_XXIII_6">VI</a>. The movements of their adapted fluids + in the various vessels of the body are carried forwards by the actions of + those vessels in consequence of two kinds of stimulus, one of which may + be compared to a pleasurable sensation or desire inducing the vessel to + seize, and, as it were, to swallow the particles thus selected from the + blood; as is done by the mouths of the various glands, veins, and other + absorbents, which may be called glandular appetency. The other kind of + stimulus may be compared to disagreeable sensation, or aversion, as when + the heart has received the blood, and is stimulated by it to push it + forwards into the arteries; the same again stimulates the arteries to + contract, and carry forwards the blood to their extremities, the glands + and capillaries. Thus the mesenteric veins absorb the blood from the + intestines by glandular appetency, and carry it forward to the vena + portarum; which acting as an artery contracts itself by disagreeable + stimulus, and pushes it to its ramified extremities, the various glands, + which constitute the liver.</p> + + <p>It seems probable, that at the beginning of the formation of these + vessels in the embryon, an agreeable sensation was in reality felt by the + glands during secretion, as is now felt in the act of swallowing + palatable food; and that a disagreeable sensation was originally felt by + the heart from the distention occasioned by the blood, or by its chemical + stimulus; but that by habit these are all become irritative motions; that + is, such motions as do not affect the whole system, except when the + vessels are diseased by inflammation.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXIV">XXIV</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE SECRETIONS OF SALIVA, AND OF TEARS, AND OF +THE LACRYMAL SACK.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXIV_1">I</a>. <i>Secretion of saliva increased by + mercury in the blood.</i> <a href="#sect_XXIV_1_1">1</a>. <i>By the food + in the mouth. Dryness of the mouth not from a deficiency of saliva.</i> + <a href="#sect_XXIV_1_2">2</a>. <i>By Sensitive ideas.</i> <a + href="#sect_XXIV_1_3">3</a>. <i>By volition.</i> <a + href="#sect_XXIV_1_4">4</a>. <i>By distasteful substances. It is secreted + in a dilute and saline state. It then becomes more viscid.</i> <a + href="#sect_XXIV_1_5">5</a>. <i>By ideas of distasteful substances.</i> + <a href="#sect_XXIV_1_6">6</a>. <i>By nausea.</i> <a + href="#sect_XXIV_1_7">7</a>. <i>By aversion.</i> <a + href="#sect_XXIV_1_8">8</a>. <i>By catenation with stimulating substances + in the ear.</i> <a href="#sect_XXIV_2">II</a>. <a + href="#sect_XXIV_2_1">1</a>. <i>Secretion of tears less in sleep. From + stimulation of their excretory duct.</i> <a href="#sect_XXIV_2_2">2</a>. + <i>Lacrymal sack is a gland.</i> <a href="#sect_XXIV_2_3">3</a>. <i>Its + uses.</i> <a href="#sect_XXIV_2_4">4</a>. <i>Tears are secreted, when the + nasal duct is stimulated.</i> <a href="#sect_XXIV_2_5">5</a>. <i>Or when + it is excited by sensation.</i> <a href="#sect_XXIV_2_6">6</a>. <i>Or by + volition.</i> <a href="#sect_XXIV_2_7">7</a>. <i>The lacrymal sack can + regurgitate its contents into the eye.</i> <a + href="#sect_XXIV_2_8">8</a>. <i>More tears are secreted by association + with the irritation of the nasal duct of the lacrymal sack, than the + puncta lacrymalia can imbibe. Of the gout in the liver and + stomach.</i></p> + +</blockquote> + + <p><a name="sect_XXIV_1">I</a>. The salival glands drink up a certain + fluid from the circumfluent blood, and pour it into the mouth. They are + sometimes stimulated into action by the blood, that surrounds their + origin, or by some part of that heterogeneous fluid: for when mercurial + salts, or oxydes, are mixed with the blood, they stimulate these glands + into unnatural exertions; and then an unusual quantity of saliva is + separated.</p> + + <p><a name="sect_XXIV_1_1">1</a>. As the saliva secreted by these glands + is most wanted during the mastication of our food, it happens, when the + terminations of their ducts in the mouth are stimulated into action, the + salival glands themselves are brought into increased action at the same + time by association, and separate a greater quantity of their juices from + the blood; in the same manner as tears are produced in greater abundance + during the stimulus of the vapour of onions, or of any other acrid + material in the eye.</p> + + <p>The saliva is thus naturally poured into the mouth only during the + stimulus of our food in mastication; for when there is too great an + exhalation of the mucilaginous secretion 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 saliva; as in those who + sleep with their mouths open, and in some fevers.</p> + + <p><a name="sect_XXIV_1_2">2</a>. Though during the mastication of our + natural food the salival glands are excited into action by the stimulus + on their excretory ducts, and a due quantity of saliva is separated from + the blood, and poured into the mouth; yet as this mastication of our food + is always attended with a degree of pleasure; and that pleasurable + sensation is also connected with our ideas of certain kinds of aliment; + it follows, that when these ideas are reproduced, the pleasurable + sensation arises along with them, and the salival glands are excited into + action, and fill the mouth with saliva from this sensitive association, + as is frequently seen in dogs, who slaver at the sight of food.</p> + + <p><a name="sect_XXIV_1_3">3</a>. We have also a voluntary power over the + action of these salival glands, for we can at any time produce a flow of + saliva into our mouth, and spit out, or swallow it at will.</p> + + <p><a name="sect_XXIV_1_4">4</a>. If any very acrid material be held in + the mouth, as the root of pyrethrum, or the leaves of tobacco, the + salival glands are stimulated into stronger action than is natural, and + thence secrete a much larger quantity of saliva; which is at the same + time more viscid than in its natural state; because the lymphatics, that + open their mouths into the ducts of the salival glands, and on the + membranes, which line the mouth, are likewise stimulated into stronger + action, and absorb the more liquid parts of the saliva with greater + avidity; and the remainder is left both in greater quantity and more + viscid.</p> + + <p>The increased absorption in the mouth by some stimulating substances, + which are called astringents, as crab juice, is evident from the instant + dryness produced in the mouth by a small quantity of them.</p> + + <p>As the extremities of the glands are of exquisite tenuity, as appears + by their difficulty of injection, it was necessary for them to secrete + their fluids in a very dilute state; and, probably for the purpose of + stimulating them into action, a quantity of neutral salt is likewise + secreted or formed by the gland. This aqueous and saline part of all + secreted fluids is again reabsorbed into the habit. More than half of + some secreted fluids is thus imbibed from the reservoirs, into which they + are poured; as in the urinary bladder much more than half of what is + secreted by the kidneys becomes reabsorbed by the lymphatics, which are + thickly dispersed around the neck of the bladder. This seems to be the + purpose of the urinary bladders of fish, as otherwise such a receptacle + for the urine could have been of no use to an animal immersed in + water.</p> + + <p><a name="sect_XXIV_1_5">5</a>. The idea of substances disagreeably + acrid will also produce a quantity of saliva in the mouth; as when we + smell very putrid vapours, we are induced to spit out our saliva, as if + something disagreeable was actually upon our palates.</p> + + <p><a name="sect_XXIV_1_6">6</a>. When disagreeable food in the stomach + produces nausea, a flow of saliva is excited in the mouth by association; + as efforts to vomit are frequently produced by disagreeable drugs in the + mouth by the same kind of association.</p> + + <p><a name="sect_XXIV_1_7">7</a>. A preternatural flow of saliva is + likewise sometimes occasioned by a disease of the voluntary power; for if + we think about our saliva, and determine not to swallow it, or not to + spit it out, an exertion is produced by the will, and more saliva is + secreted against our wish; that is, by our aversion, which bears the same + analogy to desire, as pain does to pleasure; as they are only + modifications of the same disposition of the sensorium. See Class IV. 3. + 2. 1.</p> + + <p><a name="sect_XXIV_1_8">8</a>. The quantity of saliva may also be + increased beyond what is natural, by the catenation of the motions of + these glands with other motions, or sensations, as by an extraneous body + in the ear; of which I have known an instance; or by the application of + stizolobium, siliqua hirsuta, cowhage, to the seat of the parotis, as + some writers have affirmed.</p> + + <p><a name="sect_XXIV_2">II</a>. <a name="sect_XXIV_2_1">1</a>. 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 eyelids. Though it may perhaps be stimulated into the performance + of its natural action by the blood, which surrounds its origin, or by + some part of that heterogeneous fluid; yet as the tears secreted by this + gland are more wanted at some times than at others, its secretion is + variable, like that of the saliva above mentioned, and is chiefly + produced when its excretory duct is stimulated; for in our common sleep + there seems to be little or no secretion of tears; though they are + occasionally produced by our sensations in dreams.</p> + + <p>Thus when any extraneous material on the eye-ball, or the dryness of + the external covering of it, or the coldness of the air, or the acrimony + of some vapours, as of onions, stimulates the excretory duct of the + lacrymal gland, it discharges its contents upon the ball; a quicker + secretion takes place in the gland, and abundant tears succeed, to + moisten, clean, and lubricate the eye. These by frequent nictitation are + diffused over the whole ball, and as the external angle of the eye in + winking is closed sooner than the internal angle, the tears are gradually + driven forwards, and downwards from the lacrymal gland to the puncta + lacrymalia.</p> + + <p><a name="sect_XXIV_2_2">2</a>. The lacrymal sack, with its puncta + lacrymalia, and its nasal duct, is a complete gland; and is singular in + this respect, that it neither derives its fluid from, nor disgorges it + into the circulation. The simplicity of the structure of this gland, and + both the extremities of it being on the surface of the body, makes it + well worthy our minuter observation; as the actions of more intricate and + concealed glands may be better understood from their analogy to this.</p> + + <p><a name="sect_XXIV_2_3">3</a>. This simple gland consists of two + absorbing mouths, a belly, and an excretory duct. As the tears are + brought to the internal angle of the eye, these two mouths drink them up, + being stimulated into action by this fluid, which they absorb. The belly + of the gland, or lacrymal sack, is thus filled, in which the saline part + of the tears is absorbed, and when the other end of the gland, or nasal + duct, is stimulated by the dryness, or pained by the coldness of the air, + or affected by any acrimonious dust or vapour in the nostrils, it is + excited into action together with the sack, and the tears are disgorged + upon the membrane, which lines the nostrils; where they serve a second + purpose to moisten, clean, and lubricate, the organ of smell.</p> + + <p><a name="sect_XXIV_2_4">4</a>. When the nasal duct of this gland is + stimulated by any very acrid material, as the powder of tobacco, or + volatile spirits, it not only disgorges the contents of its belly or + receptacle (the lacrymal sack), and absorbs hastily all the fluid, that + is ready for it in the corner of the eye; but by the association of its + motions with those of the lacrymal gland, it excites that also into + increased action, and a large flow of tears is poured into the eye.</p> + + <p><a name="sect_XXIV_2_5">5</a>. This nasal duct is likewise excited + into strong action by sensitive ideas, as in grief, or joy, and then also + by its associations with the lacrymal gland it produces a great flow of + tears without any external stimulus; as is more fully explained in Sect. + <a href="#sect_XVI_8">XVI. 8</a>. on Instinct.</p> + + <p><a name="sect_XXIV_2_6">6</a>. There are some, famous in the arts of + exciting compassion, who are said to have acquired a voluntary power of + producing a flow of tears in the eye; which, from what has been said in + the section on Instinct above mentioned, I should suspect, is performed + by acquiring a voluntary power over the action of this nasal duct.</p> + + <p><a name="sect_XXIV_2_7">7</a>. There is another circumstance well + worthy our attention, that when by any accident this nasal duct is + obstructed, the lacrymal sack, which is the belly or receptacle of this + gland, by slight pressure of the finger is enabled to disgorge its + contents again into the eye; perhaps the bile in the same manner, when + the biliary ducts are obstructed, is returned into the blood by the + vessels which secrete it?</p> + + <p><a name="sect_XXIV_2_8">8</a>. A very important though minute + occurrence must here be observed, that though the lacrymal gland is only + excited into action, when we weep at a distressful tale, by its + association with this nasal duct, as is more fully explained in Sect. <a + href="#sect_XVI_8">XVI. 8</a>; yet the quantity of tears secreted at once + is more than the puncta lacrymalia can readily absorb; which shews + <i>that the motions occasioned by associations are frequently more + energetic than the original motions, by which they were occasioned</i>. + Which we shall have occasion to mention hereafter, to illustrate, why + pains frequently exist in a part distant from the cause of them, as in + the other end of the urethra, when a stone stimulates the neck of the + bladder. And why inflammations frequently arise in parts distant from + their cause, as the gutta rosea of drinking people, from an inflamed + liver.</p> + + <p>The inflammation of a part is generally preceded by a torpor or + quiescence of it; if this exists in any large congeries of glands, as in + the liver, or any membranous part, as the stomach, pain is produced and + chilliness in consequence of the torpor of the vessels. In this situation + sometimes an inflammation of the parts succeeds the torpor; at other + times a distant more sensible part becomes inflamed; whose actions have + previously been associated with it; and the torpor of the first part + ceases. This I apprehend happens, when the gout of the foot succeeds a + pain of the biliary duct, or of the stomach. Lastly, it sometimes + happens, that the pain of torpor exists without any consequent + inflammation of the affected part, or of any distant part associated with + it, as in the membranes about the temple and eye-brows in hemicrania, and + in those pains, which occasion convulsions; if this happens to gouty + people, when it affects the liver, I suppose epileptic fits are produced; + and, when it affects the stomach, death is the consequence. In these + cases the pulse is weak, and the extremities cold, and such medicines as + stimulate the quiescent parts into action, or which induce inflammation + in them, or in any distant part, which is associated with them, cures the + present pain of torpor, and saves the patient.</p> + + <p>I have twice seen 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 affected with gout, and + the inflammation of their livers ceased. It is probable, that the uneasy + sensations about the stomach, and indigestion, which precedes gouty + paroxysms, are generally owing to torpor or slight inflammation of the + liver, and biliary ducts; but where great pain with continued sickness, + with feeble pulse, and sensation of cold, affect the stomach in patients + debilitated by the gout, that it is a torpor of the stomach itself, and + destroys the patient from the great connexion of that viscus with the + vital organs. See Sect. <a href="#sect_XXV_17">XXV. 17</a>.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXV">XXV</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE STOMACH AND INTESTINES.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXV_1">1</a>. <i>Of swallowing our food. Ruminating + animals.</i> <a href="#sect_XXV_2">2</a>. <i>Action of the stomach.</i> + <a href="#sect_XXV_3">3</a>. <i>Action of the intestines. Irritative + motions connected with these.</i> <a href="#sect_XXV_4">4</a>. <i>Effects + of repletion.</i> <a href="#sect_XXV_5">5</a>. <i>Stronger action of the + stomach and intestines from more stimulating food.</i> <a + href="#sect_XXV_6">6</a>. <i>Their action inverted by still greater + stimuli. Or by disgustful ideas. Or by volition.</i> <a + href="#sect_XXV_7">7</a>. <i>Other glands strengthen or invert their + motions by sympathy.</i> <a href="#sect_XXV_8">8</a>. <i>Vomiting + performed by intervals.</i> <a href="#sect_XXV_9">9</a>. <i>Inversion of + the cutaneous absorbents.</i> <a href="#sect_XXV_10">10</a>. <i>Increased + secretion of bile and pancreatic juice.</i> <a + href="#sect_XXV_11">11</a>. <i>Inversion of the lacteals.</i> <a + href="#sect_XXV_12">12</a>. <i>And of the bile-ducts.</i> <a + href="#sect_XXV_13">13</a>. <i>Case of a cholera.</i> <a + href="#sect_XXV_14">14</a>. <i>Further account of the inversion of + lacteals.</i> <a href="#sect_XXV_15">15</a>. <i>Iliac passions. Valve of + the colon.</i> <a href="#sect_XXV_16">16</a>. <i>Cure of the iliac + passion.</i> <a href="#sect_XXV_17">17</a>. <i>Pain of gall-stone + distinguished from pain of the stomach. Gout of the stomach from torpor, + from inflammation. Intermitting pulse owing to indigestion. To overdose + of foxglove. Weak pulse from emetics. Death from a blow on the stomach. + From gout of the stomach.</i></p> + +</blockquote> + + <p><a name="sect_XXV_1">1</a>. The throat, stomach, and intestines, may + be considered as one great gland; which like the lacrymal sack above + mentioned, neither begins nor ends in the circulation. Though the act of + masticating our aliment belongs to the sensitive class of motions, for + the pleasure of its taste induces the muscles of the jaw into action; yet + the deglutition of it when masticated is generally, if not always, an + irritative motion, occasioned by the application of the food already + masticated to the origin of the pharinx; in the same manner as we often + swallow our spittle without attending to it.</p> + + <p>The ruminating class of animals have the power to invert the motion of + their gullet, and of their first stomach, from the stimulus 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, whilst they are employed in this second mastication of their + food.</p> + + <p><a name="sect_XXV_2">2</a>. When our natural aliment arrives into the + stomach, this organ is simulated into its proper vermicular action; which + beginning at the upper orifice of it, and terminating at the lower one, + gradually mixes together and pushes forwards the digesting materials into + the intestine beneath it.</p> + + <p>At the same time the glands, that supply the gastric juices, which are + necessary to promote the chemical part of the process of digestion, are + stimulated to discharge their contained fluids, and to separate a further + supply from the blood-vessels: and the lacteals or lymphatics, which open + their mouths into the stomach, are stimulated into action, and take up + some part of the digesting materials.</p> + + <p><a name="sect_XXV_3">3</a>. The remainder of these digesting materials + is carried forwards into the upper intestines, and stimulates them into + their peristaltic motion similar to that of the stomach; which continues + gradually to mix the changing materials, and pass them along through the + valve of the colon to the excretory end of this great gland, the + sphincter ani.</p> + + <p>The digesting materials produce a flow of bile, and of pancreatic + juice, as they pass along the duodenum, by stimulating the excretory + ducts of the liver and pancreas, which terminate in that intestine: and + other branches of the absorbent or lymphatic system, called lacteals, are + excited to drink up, as it passes, those parts of the digesting + materials, that are proper for their purpose, by its stimulus on their + mouths.</p> + + <p><a name="sect_XXV_4">4</a>. When the stomach and intestines are thus + filled with their proper food, not only the motions of the gastric + glands, the pancreas, liver, and lacteal vessels, are excited into + action; but at the same time the whole tribe of irritative motions are + exerted with greater energy, a greater degree of warmth, colour, + plumpness, and moisture, is given to the skin from the increased action + of those glands called capillary vessels; pleasurable sensation is + excited, the voluntary motions are less easily exerted, and at length + suspended; and sleep succeeds, unless it be prevented by the stimulus of + surrounding objects, or by voluntary exertion, or by an acquired habit, + which was originally produced by one or other of these circumstances, as + is explained in Sect. <a href="#sect_XXI">XXI</a>. on Drunkenness.</p> + + <p>At this time also, as the blood-vessels become replete with chyle, + more urine is separated into the bladder, and less of it is reabsorbed; + more mucus poured into the cellular membranes, and less of it reabsorbed; + the pulse becomes fuller, and softer, and in general quicker. The reason + why less urine and cellular mucus is absorbed after a full meal with + sufficient drink is owing to the blood-vessels being fuller: hence one + means to promote absorption is to decrease the resistance by emptying the + vessels by venesection. From this decreased absorption the urine becomes + pale as well as copious, and the skin appears plump as well as + florid.</p> + + <p>By daily repetition of these movements they all become connected + together, and make a diurnal circle of irritative action, and if one of + this chain be disturbed, the whole is liable to be put into disorder. See + Sect. <a href="#sect_XX">XX</a>. on Vertigo.</p> + + <p><a name="sect_XXV_5">5</a>. When the stomach and intestines receive a + quantity of food, whose stimulus is greater than usual, all their + motions, and those of the glands and lymphatics, are stimulated into + stronger action than usual, and perform their offices with greater vigour + and in less time: such are the effects of certain quantities of spice or + of vinous spirit.</p> + + <p><a name="sect_XXV_6">6</a>. But if the quantity or duration of these + stimuli are still further increased, the stomach and throat are + stimulated into a motion, whose direction is contrary to the natural one + above described; and they regurgitate the materials, which they contain, + instead of carrying them forwards. This retrograde motion of the stomach + may be compared to the stretchings of wearied limbs the contrary way, and + is well elucidated by the following experiment. Look earnestly for a + minute or two on an area an inch square of pink silk, placed in a strong + light, the eye becomes fatigued, the colour becomes faint, and at length + vanishes, for the fatigued eye can no longer be stimulated into direct + motions; then on closing the eye a green spectrum will appear in it, + which is a colour directly contrary to pink, and which will appear and + disappear repeatedly, like the efforts in vomiting. See Section <a + href="#sect_XXIX_11">XXIX. 11</a>.</p> + + <p>Hence all those drugs, which by their bitter or astringent stimulus + increase the action of the stomach, as camomile and white vitriol, if + their quantity is increased above a certain dose become emetics.</p> + + <p>These inverted motions of the stomach and throat are generally + produced from the stimulus of unnatural food, and are attended with the + sensation of nausea or sickness: but as this sensation is again connected + with an idea of the distasteful food, which induced it; so an idea of + nauseous food will also sometimes excite the action of nausea; and that + give rise by association to the inversion of the motions of the stomach + and throat. As some, who have had horse-flesh or dogs-flesh given them + for beef or mutton, are said to have vomited many hours afterwards, when + they have been told of the imposition.</p> + + <p>I have been told of a person, who had gained a voluntary command over + these inverted motions of the stomach and throat, and supported himself + by exhibiting this curiosity to the public. At these exhibitions he + swallowed a pint of red rough gooseberries, and a pint of white smooth + ones, brought them up in small parcels into his mouth, and restored them + separately to the spectators, who called for red or white as they + pleased, till the whole were redelivered.</p> + + <p><a name="sect_XXV_7">7</a>. At the same time that these motions of the + stomach and throat are stimulated into inversion, some of the other + irritative motions, that had acquired more immediate connexions with the + stomach, as those of the gastric glands, are excited into stronger action + by this association; and some other of these motions, which are more + easily excited, as those of the gastric lymphatics, are inverted by their + association with the retrograde motions of the stomach, and regurgitate + their contents, and thus a greater quantity of mucus, and of lymph, or + chyle, is poured into the stomach, and thrown up along with its + contents.</p> + + <p><a name="sect_XXV_8">8</a>. These inversions of the motion of the + stomach in vomiting are performed by intervals, for the same reason that + many other motions are reciprocally exerted and relaxed; for during the + time of exertion the stimulus, or sensation, which caused this exertion, + is not perceived; but begins to be perceived again, as soon as the + exertion ceases, and is some time in again producing its effect. As + explained in Sect. <a href="#sect_XXXIV">XXXIV</a>. on Volition, where it + is shewn, that the contractions of the fibres, and the sensation of pain, + which occasioned that exertion, cannot exist at the same time. The + exertion ceases from another cause also, which is the exhaustion of the + sensorial power of the part, and these two causes frequently operate + together.</p> + + <p><a name="sect_XXV_9">9</a>. At the times of these inverted efforts of + the stomach not only the lymphatics, which open their mouths into the + stomach, but those of the skin also, are for a time inverted; for sweats + are sometimes pushed out during the efforts of vomiting without an + increase of heat.</p> + + <p><a name="sect_XXV_10">10</a>. But if by a greater stimulus the motions + of the stomach are inverted still more violently or more permanently, the + duodenum has its peristaltic motions inverted at the same time by their + association with those of the stomach; and the bile and pancreatic juice, + which it contains, are by the inverted motions brought up into the + stomach, and discharged along with its contents; while a greater quantity + of bile and pancreatic juice is poured into this intestine; as the + glands, that secrete them, are by their association with the motions of + the intestine excited into stronger action than usual.</p> + + <p><a name="sect_XXV_11">11</a>. The other intestines are by association + excited into more powerful action, while the lymphatics, that open their + mouths into them, suffer an inversion of their motions corresponding with + the lymphatics of the stomach, and duodenum; which with a part of the + abundant secretion of bile is carried downwards, and contributes both to + stimulate the bowels, and to increase the quantity of the evacuations. + This inversion of the motion of the lymphatics appears from the quantity + of chyle, which comes away by stools; which is otherwise absorbed as soon + as produced, and by the immense quantity of thin fluid, which is + evacuated along with it.</p> + + <p><a name="sect_XXV_12">12</a>. But if the stimulus, which inverts the + stomach, be still more powerful, or more permanent, it sometimes happens, + that the motions of the biliary glands, and of their excretory ducts, are + at the same time inverted, and regurgitate their contained bile into the + blood-vessels, as appears by the yellow colour of the skin, and of the + urine; and it is probable the pancreatic secretion may suffer an + inversion at the same time, though we have yet no mark by which this can + be ascertained.</p> + + <p><a name="sect_XXV_13">13</a>. Mr. —— eat two putrid + pigeons out of a cold pigeon-pye, and drank about a pint of beer and ale + along with them, and immediately rode about five miles. He was then + seized with vomiting, which was after a few periods succeeded by purging; + these continued alternately for two hours; and the purging continued by + intervals for six or eight hours longer. During this time he could not + force himself to drink more than one pint in the whole; this great + inability to drink was owing to the nausea, or inverted motions of the + stomach, which the voluntary exertion of swallowing could seldom and with + difficulty overcome; yet he discharged in the whole at least six quarts; + whence came this quantity of liquid? First, the contents of the stomach + were emitted, 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 lacteal vessels, and in the receptacle of chyle, was + regurgitated into the intestines by a retrograde motion of these vessels. + And afterwards the mucus deposited in the cellular membrane, and on the + surface of all the other membranes, seems to have been absorbed; and with + the fluid absorbed from the air to have been carried up their respective + lymphatic branches by the increased energy of their natural motions, and + down the visceral lymphatics, or lacteals, by the inversion of their + motions.</p> + + <p><a name="sect_XXV_14">14</a>. It may be difficult to invent + experiments to demonstrate the truth of this inversion of some branches + of the absorbent system, and increased absorption of others, but the + analogy of these vessels to the intestinal canal, and the symptoms of + many diseases, render this opinion more probable than many other received + opinions of the animal œconomy.</p> + + <p>In the above instance, after the yellow excrement was voided, the + fluid ceased to have any smell, and appeared like curdled milk, and then + a thinner fluid, and some mucus, were evacuated; did not these seem to + partake of the chyle, of the mucous fluid from all the cells of the body, + and lastly, of the atmospheric moisture? All these facts may be easily + observed by any one, who takes a brisk purge.</p> + + <p><a name="sect_XXV_15">15</a>. Where the stimulus on the stomach, or on + some other part of the intestinal canal, is still more permanent, not + only the lacteal vessels, but the whole canal itself, becomes inverted + from its associations: this is the iliac passion, 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.</p> + + <p>The structure of this valve may be represented by a flexile leathern + pipe standing up from the bottom of a vessel of water: its sides collapse + by the pressure of the ambient fluid, as a small part of that fluid + passes through it; but if it has a living power, and by its inverted + action keeps itself open, it becomes like a rigid pipe, and will admit + the whole liquid to pass. See Sect. <a href="#sect_XXIX_2_5">XXIX. 2. + 5</a>.</p> + + <p>In this case the patient is averse to drink, from the constant + inversion of the motions of the stomach, and yet many quarts are daily + ejected from the stomach, which at length smell of excrement, and at last + seem to be only a thin mucilaginous or aqueous liquor.</p> + + <p>From whence is it possible, that this great quantity of fluid for many + successive days can be supplied, after the cells of the body have given + up their fluids, but from the atmosphere? When the cutaneous branch of + absorbents acts with unnatural strength, it is probable the intestinal + branch has its motions inverted, and thus a fluid is supplied without + entering the arterial system. Could oiling or painting the skin give a + check to this disease?</p> + + <p>So when the stomach has its motions inverted, the lymphatics of the + stomach, which are most strictly associated with it, invert their motions + at the same time. But the more distant branches of lymphatics, which are + less strictly associated with it, act with increased energy; as the + cutaneous lymphatics in the cholera, or iliac passion, above described. + And other irritative motions become decreased, as the pulsations of the + arteries, from the extra-derivation or exhaustion of the sensorial + power.</p> + + <p>Sometimes when stronger vomiting takes place the more distant branches + of the lymphatic system invert their motions with those of the stomach, + and loose stools are produced, and cold sweats.</p> + + <p>So when the lacteals have their motions inverted, as during the + operation of strong purges, the urinary and cutaneous absorbents have + their motions increased to supply the want of fluid in the blood, as in + great thirst; but after a meal with sufficient potation the urine is + pale, that is, the urinary absorbents act weakly, no supply of water + being wanted for the blood. And when the intestinal absorbents act too + violently, as when too great quantities of fluid have been drank, the + urinary absorbents invert their motions to carry off the superfluity, + which is a new circumstance of association, and a temporary diabetes + supervenes.</p> + + <p><a name="sect_XXV_16">16</a>. I have had the opportunity of seeing + four patients in the iliac passion, where the ejected material smelled + and looked like excrement. Two of these were so exhausted at the time I + saw them, that more blood could not be taken from them, and as their pain + had ceased, and they continued to vomit up every thing which they drank, + I suspected 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 less preceding pain in old and weak people, these both + died. The other two, who were both young men, had still pain and strength + sufficient for further venesection, and they neither of them had any + appearance of hernia, both recovered by repeated bleeding, and a scruple + of calomel given to one, and half a dram to the other, in very small + pills: the usual means of clysters, and purges joined with opiates, had + been in vain attempted. I have thought an ounce or two of crude mercury + in less violent diseases of this kind has been of use, by contributing to + restore its natural motion to some part of the intestinal canal, either + by its weight or stimulus; and that hence the whole tube recovered its + usual associations of progressive peristaltic motion. I have in three + cases seen crude mercury given in small doses, as one or two ounces twice + a day, have great effect in stopping pertinacious vomitings.</p> + + <p><a name="sect_XXV_17">17</a>. Besides the affections above described, + the stomach is liable, like many other membranes of the body, to torpor + without consequent inflammation: as happens to the membranes about the + head in some cases of hemicrania, or in general head-ach. This torpor of + the stomach is attended with indigestion, and consequent flatulency, and + with pain, which is usually called the cramp of the stomach, and is + relievable by aromatics, essential oils, alcohol, or opium.</p> + + <p>The intrusion of a gall-stone into the common bile-duct from the + gall-bladder is sometimes mistaken for a pain of the stomach, as neither + of them are attended with fever; but in the passage of a gall-stone, the + pain is confined to a less space, which is exactly where the common + bile-duct enters the duodenum, as explained in Section <a + href="#sect_XXX_1_3">XXX. 1. 3</a>. Whereas in this gastrodynia the pain + is diffused over the whole stomach; and, like other diseases from torpor, + the pulse is weaker, and the extremities colder, and the general debility + greater, than in the passage of a gall-stone; for in the former the + debility is the consequence of the pain, in the latter it is the cause of + it.</p> + + <p>Though the first fits of the gout, I believe, commence with a torpor + of the liver; and the ball of the toe becomes inflamed instead of the + membranes of the liver in consequence of this torpor, as a coryza or + catarrh frequently succeeds a long exposure of the feet to cold, as in + snow, or on a moist brick-floor; yet in old or exhausted constitutions, + which have been long habituated to its attacks, it sometimes commences + with a torpor of the stomach, and is transferable to every membrane of + the body. When the gout begins with torpor of the stomach, a painful + sensation of cold occurs, which the patient compares to ice, with weak + pulse, cold extremities, and sickness; this in its slighter degree is + relievable by spice, wine, or opium; in its greater degree it is + succeeded by sudden death, which is owing to the sympathy of the stomach + with the heart, as explained below.</p> + + <p>If the stomach becomes inflamed in consequence of this gouty torpor of + it, or in consequence of its sympathy with some other part, the danger is + less. A sickness and vomiting continues many days, or even weeks, the + stomach rejecting every thing stimulant, even opium or alcohol, together + with much viscid mucus; till the inflammation at length ceases, as + happens when other membranes, as those of the joints, are the seat of + gouty inflammation; as observed in Sect. <a href="#sect_XXIV_2_8">XXIV. + 2. 8</a>.</p> + + <p>The sympathy, or association of motions, between those of the stomach + and those of the heart, are evinced in many diseases. First, many people + are occasionally affected with an intermission of their pulse for a few + days, which then ceases again. In this case there is a stop of the motion + of the heart, and at the same time a tendency to eructation from the + stomach. As soon as the patient feels a tendency to the intermission of + the motion of his heart, if he voluntarily brings up wind from his + stomach, the stop of the heart does not occur. From hence I conclude that + the stop of digestion is the primary disease; and that air is instantly + generated from the aliment, which begins to ferment, if the digestive + process is impeded for a moment, (see Sect. <a + href="#sect_XXIII_4">XXIII. 4</a>.); and that the stop of the heart is in + consequence of the association of the motions of these viscera, as + explained in Sect. <a href="#sect_XXXV_1_4">XXXV. 1. 4</a>.; but if the + little air, which is instantly generated during the temporary torpor of + the stomach, be evacuated, the digestion recommences, and the temporary + torpor of the heart does not follow. One patient, whom I lately saw, and + who had been five or six days much troubled with this intermission of a + pulsation of his heart, and who had hemicrania with some fever, was + immediately relieved from them all by losing ten ounces of blood, which + had what is termed an inflammatory crust on it.</p> + + <p>Another instance of this association between the motions of the + stomach and heart is evinced by the exhibition of an over dose of + foxglove, which induces an incessant vomiting, which is attended with + very slow, and sometimes intermitting pulse.—Which continues in + spite of the exhibition of wine and opium for two or three days. To the + same association must be ascribed the weak pulse, which constantly + attends the exhibition of emetics during their operation. And also the + sudden deaths, which have been occasioned in boxing by a blow on the + stomach; and lastly, the sudden death of those, who have been long + debilitated by the gout, from the torpor of the stomach. See Sect. <a + href="#sect_XXXV_1_4">XXXV. 1. 4</a>.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXVI">XXVI</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE CAPILLARY GLANDS AND MEMBRANES.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXVI_1">I</a>. <a href="#sect_XXVI_1_1">1</a>. <i>The + capillary vessels are glands.</i> <a href="#sect_XXVI_1_2">2</a>. + <i>Their excretory ducts. Experiments on the mucus of the intestines, + abdomen, cellular membrane, and on the humours of the eye.</i> <a + href="#sect_XXVI_1_3">3</a>. <i>Scurf on the head, cough, catarrh, + diarrhœa, gonorrhœa.</i> <a href="#sect_XXVI_1_4">4</a>. + <i>Rheumatism. Gout. Leprosy.</i> <a href="#sect_XXVI_2">II</a>. <a + href="#sect_XXVI_2_1">1</a>. <i>The most minute membranes are + unorganized.</i> <a href="#sect_XXVI_2_2">2</a>. <i>Larger membranes are + composed of the ducts of the capillaries, and the mouths of the + absorbents.</i> <a href="#sect_XXVI_2_3">3</a>. <i>Mucilaginous fluid is + secreted on their surfaces.</i> <a href="#sect_XXVI_3">III</a>. <i>Three + kinds of rheumatism.</i></p> + +</blockquote> + + <p><a name="sect_XXVI_1">I</a>. <a name="sect_XXVI_1_1">1</a>. The + capillary-vessels are like all the other glands except the absorbent + system, inasmuch as they receive blood from the arteries, separate a + fluid from it, and return the remainder by the veins.</p> + + <p><a name="sect_XXVI_1_2">2</a>. This series of glands is of the most + extensive use, as their excretory ducts open on the whole external skin + forming its perspirative pores, and on the internal surfaces of every + cavity of the body. Their secretion on the skin is termed insensible + perspiration, which in health is in part reabsorbed by the mouths of the + lymphatics, and in part evaporated in the air; the secretion on the + membranes, which line the larger cavities of the body, which have + external openings, as the mouth and intestinal canal, is termed mucus, + but is not however coagulable by heat; and the secretion on the membranes + of those cavities of the body, which have no external openings, is called + lymph or water, as in the cavities of the cellular membrane, and of the + abdomen; this lymph however is coagulable by the heat of boiling water. + Some mucus nearly as viscid as the white of egg, which was discharged by + stool, did not coagulate, though I evaporated it to one fourth of the + quantity, nor did the aqueous and vitreous humours of a sheep's eye + coagulate by the like experiment: but the serosity from an anasarcous + leg, and that from the abdomen of a dropsical person, and the crystalline + humour of a sheep's eye, coagulated in the same heat.</p> + + <p><a name="sect_XXVI_1_3">3</a>. When any of these capillary glands are + stimulated into greater irritative actions, than is natural, they secrete + a more copious material; and as the mouths of the absorbent system, which + open in their vicinity, are at the same time stimulated into greater + action, the thinner and more saline part of the secreted fluid is taken + up again; and the remainder is not only more copious but also more viscid + than natural. This is more or less troublesome or noxious according to + the importance of the functions of the part affected: on the skin and + bronchiæ, where this secretion ought naturally to evaporate, it becomes + so viscid as to adhere to the membrane; on the tongue it forms a + pellicle, which can with difficulty be scraped off; produces the scurf on + the heads of many people; and the mucus, which is spit up by others in + coughing. On the nostrils and fauces, when the secretion of these + capillary glands is increased, it is termed simple catarrh; when in the + intestines, a mucous diarrhœa; and in the urethra, or vagina, it has + the name of gonorrhœa, or fluor albus.</p> + + <p><a name="sect_XXVI_1_4">4</a>. When these capillary glands become + inflamed, a still more viscid or even cretaceous humour is produced upon + the surfaces of the membranes, which is the cause or the effect of + rheumatism, gout, leprosy, and of hard tumours of the legs, which are + generally termed scorbutic; all which will be treated of hereafter.</p> + + <p><a name="sect_XXVI_2">II</a>. <a name="sect_XXVI_2_1">1</a>. The whole + surface of the body, with all its cavities and contents, are covered with + membrane. It lines every vessel, forms every cell, and binds together all + the muscular and perhaps the osseous fibres of the body; and is itself + therefore probably a simpler substance than those fibres. And as the + containing vessels of the body from the largest to the least are thus + lined and connected with membranes, it follows that these membranes + themselves consisted of unorganized materials.</p> + + <p>For however small we may conceive the diameters of the minutest + vessels of the body, which escape our eyes and glasses, yet these vessels + must consist of coats or sides, which are made up of an unorganized + material, and which are probably produced from a gluten, which hardens + after its production, like the silk or web of caterpillars and spiders. + Of this material consist the membranes, which line the shells of eggs, + and the shell itself, both which are unorganized, and are formed from + mucus, which hardens after it is formed, either by the absorption of its + more fluid part, or by its uniting with some part of the atmosphere. Such + is also the production of the shells of snails, and of shell-fish, and I + suppose of the enamel of the teeth.</p> + + <p><a name="sect_XXVI_2_2">2</a>. But though the membranes, that compose + the sides of the most minute vessels, are in truth unorganized materials, + yet the larger membranes, which are perceptible to the eye, seem to be + composed of an intertexture of the mouths of the absorbent system, and of + the excretory ducts of the capillaries, with their concomitant arteries, + veins, and nerves: and from this construction it is evident, that these + membranes must possess great irritability to peculiar stimuli, though + they are incapable of any motions, that are visible to the naked eye: and + daily experience shews us, that in their inflamed state they have the + greatest sensibility to pain, as in the pleurisy and paronychia.</p> + + <p><a name="sect_XXVI_2_3">3</a>. On all these membranes a mucilaginous + or aqueous fluid is secreted, which moistens and lubricates their + surfaces, as was explained in Section <a href="#sect_XXIII_2">XXIII. + 2</a>. Some have doubted, whether this mucus is separated from the blood + by an appropriated set of glands, or exudes through the membranes, or is + an abrasion or destruction of the surface of the membrane itself, which + is continually repaired on the other side of it, but the great analogy + between the capillary vessels, and the other glands, countenances the + former opinion; and evinces, that these capillaries are the glands, that + secrete it; to which we must add, that the blood in passing these + capillary vessels undergoes a change in its colour from florid to purple, + and gives out a quantity of heat; from whence, as in other glands, we + must conclude that something is secreted from it.</p> + + <p><a name="sect_XXVI_3">III</a>. The seat of rheumatism is in the + membranes, or upon them; but there are three very distinct diseases, + which commonly are confounded under this name. First, when a membrane + becomes affected with torpor, or inactivity of the vessels which compose + it, pain and coldness succeed, as in the hemicrania, and other head-achs, + which are generally termed nervous rheumatism; they exist whether the + part be at rest or in motion, and are generally attended with other marks + of debility.</p> + + <p>Another rheumatism is said to exist, when inflammation and swelling, + as well as pain, affect some of the membranes of the joints, as of the + ancles, wrists, knees, elbows, and sometimes of the ribs. This is + accompanied with fever, is analogous to pleurisy and other inflammations, + and is termed the acute rheumatism.</p> + + <p>A third disease is called chronic rheumatism, which is distinguished + from that first mentioned, as in this the pain only affects the patient + during the motion of the part, and from the second kind of rheumatism + above described, as it is not attended with quick pulse or inflammation. + It is generally believed to succeed the acute rheumatism of the same + part, and that some coagulable lymph, or cretaceous, or calculous + material, has been left on the membrane; which gives pain, when the + muscles move over it, as some extraneous body would do, which was too + insoluble to be absorbed. Hence there is an analogy between this chronic + rheumatism and the diseases which produce gravel or gout-stones; and it + may perhaps receive relief from the same remedies, such as aerated sal + soda.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXVII">XXVII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF HÆMORRHAGES.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXVII_1">I</a>. <i>The veins are absorbent vessels.</i> + <a href="#sect_XXVII_1_1">1</a>. <i>Hæmorrhages from inflammation. Case + of hæmorrhage from the kidney cured by cold bathing. Case of hæmorrhage + from the nose cured by cold immersion.</i> <a + href="#sect_XXVII_2">II</a>. <i>Hæmorrhage from venous paralysis. Of + Piles. Black stools. Petechiæ. Consumption. Scurvy of the lungs. + Blackness of the face and eyes in epileptic fits. Cure of hæmorrhages + from venous inability.</i></p> + +</blockquote> + + <p><a name="sect_XXVII_1">I</a>. As the imbibing mouths of the absorbent + system already described open on the surface, and into the larger + cavities of the body, so there is another system of absorbent vessels, + which are not commonly esteemed such, I mean the veins, which take up the + blood from the various glands and capillaries, after their proper fluids + or secretions have been separated from it.</p> + + <p>The veins resemble the other absorbent vessels; as the progression of + their contents is carried on in the same manner in both, they alike + absorb their appropriated fluids, and have valves to prevent its + regurgitation by the accidents of mechanical violence. This appears + first, because there is no pulsation in the very beginnings of the veins, + as is seen by microscopes; which must happen, if the blood was carried + into them by the actions of the arteries. For though the concurrence of + various venous streams of blood from different distances must prevent any + pulsation in the larger branches, yet in the very beginnings of all these + branches a pulsation must unavoidably exist, if the circulation in them + was owing to the intermitted force of the arteries. Secondly, the venous + absorption of blood from the penis, and from the teats of female animals + after their erection, is still more similar to the lymphatic absorption, + as it is previously poured into cells, where all arterial impulse must + cease.</p> + + <p>There is an experiment, which seems to evince this venous absorption, + which consists in the external application of a stimulus to the lips, as + of vinegar, by which they become instantly pale; that is, the bibulous + mouths of the veins by this stimulus are excited to absorb the blood + faster, than it can be supplied by the usual arterial exertion. See Sect. + <a href="#sect_XXIII_5">XXIII. 5</a>.</p> + + <p>There are two kinds of hæmorrhages frequent in diseases, one is where + the glandular or capillary action is too powerfully exerted, and propels + the blood forwards more hastily, than the veins can absorb it; and the + other is, where the absorbent power of the veins is diminished, or a + branch of them is become totally paralytic.</p> + + <p><a name="sect_XXVII_1_1">1</a>. The former of these cases is known by + the heat of the part, and the general fever or inflammation that + accompanies the hæmorrhage. An hæmorrhage from the nose or from the lungs + is sometimes a crisis of inflammatory diseases, as of the hepatitis and + gout, and generally ceases spontaneously, when the vessels are + considerably emptied. Sometimes the hæmorrhage recurs by daily periods + accompanying the hot fits of fever, and ceasing in the cold fits, or in + the intermissions; this is to be cured by removing the febrile paroxysms, + which will be treated of in their place. Otherwise it is cured by + venesection, by the internal or external preparations of lead, or by the + application of cold, with an abstemious diet, and diluting liquids, like + other inflammations. Which by inducing a quiescence on those glandular + parts, that are affected, prevents a greater quantity of blood from being + protruded forwards, than the veins are capable of absorbing.</p> + + <p>Mr. B—— had an hæmorrhage from his kidney, and parted with + not less than a pint of blood a day (by conjecture) along with his urine + for above a fortnight: venesections, mucilages, balsams, preparations of + lead, the bark, alum, and dragon's blood, opiates, with a large blister + on his loins, were separately tried, in large doses, to no purpose. He + was then directed to bathe in a cold spring up to the middle of his body + only, the upper part being covered, and the hæmorrhage diminished at the + first, and ceased at the second immersion.</p> + + <p>In this case the external capillaries were rendered quiescent by the + coldness of the water, and thence a less quantity of blood was circulated + through them; and the internal capillaries, or other glands, became + quiescent from their irritative associations with the external ones; and + the hæmorrhage was stopped a sufficient time for the ruptured vessels to + contract their apertures, or for the blood in those apertures to + coagulate.</p> + + <p>Mrs. K—— had a continued haemorrhage from her nose for + some days; the ruptured vessel was not to be reached by plugs up the + nostrils, and the sensibility of her fauces was such that nothing could + be born behind the uvula. After repeated venesection, and other common + applications, she was directed to immerse her whole head into a pail of + water, which was made colder by the addition of several handfuls of salt, + and the hæmorrhage immediately ceased, and returned no more; but her + pulse continued hard, and she was necessitated to lose blood from the arm + on the succeeding day.</p> + + <p>Query, might not the cold bath instantly stop hæmorrhages from the + lungs in inflammatory cases?—for the shortness of breath of those, + who go suddenly into cold water, is not owing to the accumulation of + blood in the lungs, but to the quiescence of the pulmonary capillaries + from association, as explained in Section <a + href="#sect_XXXII_3_2">XXXII. 3. 2</a>.</p> + + <p><a name="sect_XXVII_2">II</a>. The other kind of hæmorrhage is known + from its being attended with a weak pulse, and other symptoms of general + debility, and very frequently occurs in those, who have diseased livers, + owing to intemperance in the use of fermented liquors. These + constitutions are shewn to be liable to paralysis of the lymphatic + absorbents, producing the various kinds of dropsies in Section <a + href="#sect_XXIX_5">XXIX. 5</a>. Now if any branch of the venous system + loses its power of absorption, the part swells, and at length bursts and + discharges the blood, which the capillaries or other glands circulate + through them.</p> + + <p>It sometimes happens that the large external veins of the legs burst, + and effuse their blood; but this occurs most frequently in the veins of + the intestines, as the vena portarum is liable to suffer from a schirrus + of the liver opposing the progression of the blood, which is absorbed + from the intestines. Hence the piles are a symptom of hepatic + obstruction, and hence the copious discharges 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 discharged from the veins of + the intestines.</p> + + <p>J.F. Meckel, in his Experimenta de Finibus Vasorum, published at + Berlin, 1772, mentions his discovery of a communication of a lymphatic + vessel with the gastric branch of the vena portarum. It is possible, that + when the motion of the lymphatic becomes retrograde in some diseases, + that blood may obtain a passage into it, where it anastomoses with the + vein, and thus be poured into the intestines. A discharge of blood with + the urine sometimes attends diabetes, and may have its source in the same + manner.</p> + + <p>Mr. A——, who had been a hard drinker, and had the gutta + rosacea on his face and breast, after a stroke of the palsy voided near a + quart of a black viscid material by stool: on diluting it with water it + did not become yellow, as it must have done if it had been inspissated + bile, but continued black like the grounds of coffee.</p> + + <p>But any other part of the venous system may become quiescent or + totally paralytic as well as the veins of the intestines: all which occur + more frequently in those who have diseased livers, than in any others. + Hence troublesome bleedings of the nose, or from the lungs with a weak + pulse; hence hæmorrhages from the kidneys, too great menstruation; and + hence the oozing of blood from every part of the body, and the petechiæ + in those fevers, which are termed putrid, and which is erroneously + ascribed to the thinness of the blood: for the blood in inflammatory + diseases is equally fluid before it coagulates in the cold air.</p> + + <p>Is not that hereditary consumption, which occurs chiefly in dark-eyed + people about the age of twenty, and commences with slight pulmonary + hæmorrhages without fever, a disease of this kind?—These + hæmorrhages frequently begin during sleep, when the irritability of the + lungs is not sufficient in these patients to carry on the circulation + without the assistance of volition; for in our waking hours, the motions + of the lungs are in part voluntary, especially if any difficulty of + breathing renders the efforts of volition necessary. See Class I. 2. 1. + 3. and Class III. 2. 1. 12. Another species of pulmonary consumption + which seems more certainly of scrophulous origin is described in the next + Section, <a href="#sect_XXVIII_2">No. 2.</a></p> + + <p>I have seen two cases of women, of about forty years of age, both of + whom were seized with quick weak pulse, with difficult respiration, and + who spit up by coughing much viscid mucus mixed with dark coloured blood. + They had both large vibices on their limbs, and petechiæ; in one the feet + were in danger of mortification, in the other the legs were + œdematous. To relieve the difficult respiration, about six ounces of + blood were taken from one of them, which to my surprise was sizy, like + inflamed blood: they had both palpitations or unequal pulsations of the + heart. They continued four or five weeks with pale and bloated + countenances, and did not cease spitting phlegm mixed with black blood, + and the pulse seldom slower than 130 or 135 in a minute. This blood, from + its dark colour, and from the many vibices and petechiæ, seems to have + been venous blood; the quickness of the pulse, and the irregularity of + the motion of the heart, are to be ascribed to debility of that part of + the system; as the extravasation of blood originated from the defect of + venous absorption. The approximation of these two cases to sea-scurvy is + peculiar, and may allow them to be called scorbutus pulmonalis. Had these + been younger subjects, and the paralysis of the veins had only affected + the lungs, it is probable the disease would have been a pulmonary + consumption.</p> + + <p>Last week I saw a gentleman of Birmingham, who had for ten days + laboured under great palpitation of his heart, which was so distinctly + felt by the hand, as to discountenance the idea of there being a fluid in + the pericardium. He frequently spit up mucus stained with dark coloured + blood, his pulse very unequal and very weak, with cold hands and nose. He + could not lie down at all, and for about ten days past could not sleep a + minute together, but waked perpetually with great uneasiness. Could those + symptoms be owing to very extensive adhesions of the lungs? or is this a + scorbutus pulmonalis? After a few days he suddenly got so much better as + to be able to sleep many hours at a time by the use of one grain of + powder of foxglove twice a day, and a grain of opium at night. After a + few days longer, the bark was exhibited, and the opium continued with + some wine; and the palpitations of his heart became much relieved, and he + recovered his usual degree of health, but died suddenly some months + afterwards.</p> + + <p>In epileptic fits the patients frequently become black in the face, + from the temporary paralysis of the venous system of this part. I have + known two instances where the blackness has continued many days. M. + P——, who had drank intemperately, was seized with the + epilepsy when he was in his fortieth year; in one of these fits the white + part of his eyes was left totally black with effused blood; which was + attended with no pain or heat, and was in a few weeks gradually absorbed, + changing colour as is usual with vibices from bruises.</p> + + <p>The hæmorrhages produced from the inability of the veins to absorb the + refluent blood, is cured by opium, the preparations of steel, lead, the + bark, vitriolic acid, and blisters; but these have the effect with much + more certainty, if a venesection to a few ounces, and a moderate + cathartic with four or six grains of calomel be premised, where the + patient is not already too much debilitated; as one great means of + promoting the absorption of any fluid consists in previously emptying the + vessels, which are to receive it.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXVIII">XXVIII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE PARALYSIS OF THE ABSORBENT SYSTEM.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXVIII_1">I</a>. <i>Paralysis of the lacteals, atrophy. + Distaste to animal food.</i> <a href="#sect_XXVIII_2">II</a>. <i>Cause of + dropsy. Cause of herpes. Scrophula. Mesenteric consumption. Pulmonary + consumption. Why ulcers in the lungs are so difficult to heal.</i></p> + +</blockquote> + + <p>The term paralysis has generally been used to express the loss of + voluntary motion, as in the hemiplagia, but may with equal propriety be + applied to express the disobediency of the muscular fibres to the other + kinds of stimulus; as to those of irritation or sensation.</p> + + <p><a name="sect_XXVIII_1">I</a>. There is a species of atrophy, which + has not been well understood; when the absorbent vessels of the stomach + and intestines have been long inured to the stimulus of too much + spirituous liquor, they at length, either by the too sudden omission of + fermented or spirituous potation, or from the gradual decay of nature, + become in a certain degree paralytic; now it is observed in the larger + muscles of the body, when one side is paralytic, the other is more + frequently in motion, owing to the less expenditure of sensorial power in + the paralytic limbs; so in this case the other part of the absorbent + system acts with greater force, or with greater perseverance, in + consequence of the paralysis of the lacteals; and the body becomes + greatly emaciated in a small time.</p> + + <p>I have seen several patients in this disease, of which the following + are the circumstances. 1. They were men about fifty years of age, and had + lived freely in respect to fermented liquors. 2. They lost their appetite + to animal food. 3. They became suddenly emaciated to a great degree. 4. + Their skins were dry and rough. 5. They coughed and expectorated with + difficulty a viscid phlegm. 6. The membrane of the tongue was dry and + red, and liable to become ulcerous.</p> + + <p>The inability to digest animal food, and the consequent distaste to + it, generally precedes the dropsy, and other diseases, which originate + from spirituous potation. I suppose when the stomach becomes inirritable, + that there is at the same time a deficiency of gastric acid; hence milk + seldom agrees with these patients, unless it be previously curdled, as + they have not sufficient gastric acid to curdle it; and hence vegetable + food, which is itself acescent, will agree with their stomachs longer + than animal food, which requires more of the gastric acid for its + digestion.</p> + + <p>In this disease the skin is dry from the increased absorption of the + cutaneous lymphatics, the fat is absorbed from the increased absorption + of the cellular lymphatics, the mucus of the lungs is too viscid to be + easily spit up by the increased absorption of the thinner parts of it, + the membrana sneideriana becomes dry, covered with hardened mucus, and at + length becomes inflamed and full of aphthæ, and either these sloughs, or + pulmonary ulcers, terminate the scene.</p> + + <p><a name="sect_XXVIII_2">II</a>. The immediate cause of dropsy is the + paralysis of some other branches of the absorbent system, which are + called lymphatics, and which open into the larger cavities of the body, + or into the cells of the cellular membrane; whence those cavities or + cells become distended with the fluid, which is hourly secreted into them + for the purpose of lubricating their surfaces. As is more fully explained + in <a href="#sect_XXIX_5">No. 5.</a> of the next Section.</p> + + <p>As those lymphatic vessels consist generally of a long neck or mouth, + which drinks up its appropriated fluid, and of a conglobate gland, in + which this fluid undergoes some change, it happens, that sometimes the + mouth of the lymphatic, and sometimes the belly or glandular part of it, + becomes totally or partially paralytic. In the former case, where the + mouths of the cutaneous lymphatics become torpid or quiescent, the fluid + secreted on the skin ceases to be absorbed, and erodes the skin by its + saline acrimony, and produces eruptions termed herpes, the discharge from + which is as salt, as the tears, which are secreted too fast to be + reabsorbed, as in grief, or when the puncta lacrymalia are obstructed, + and which running down the cheek redden and inflame the skin.</p> + + <p>When the mouths of the lymphatics, which open on the mucous membrane + of the nostrils, become torpid, as on walking into the air in a frosty + morning; the mucus, which continues to be secreted, has not its aqueous + and saline part reabsorbed, which running over the upper lip inflames it, + and has a salt taste, if it falls on the tongue.</p> + + <p>When the belly, or glandular part of these lymphatics, becomes torpid, + the fluid absorbed by its mouth stagnates, and forms a tumour in the + gland. This disease is called the scrophula. If these glands suppurate + externally, they gradually heal, as those of the neck; if they suppurate + without an opening on the external habit, as the mesenteric glands, a + hectic fever ensues, which destroys the patient; if they suppurate in the + lungs, a pulmonary consumption ensues, which is believed thus to differ + from that described in the preceding Section, in respect to its seat or + proximate cause.</p> + + <p>It is remarkable, that matter produced by suppuration will lie + concealed in the body many weeks, or even months, without producing + hectic fever; but as soon as the wound is opened, so as to admit air to + the surface of the ulcer, a hectic fever supervenes, even in very few + hours, which is probably owing to the azotic part of the atmosphere + rather than to the oxygene; because those medicines, which contain much + oxygene, as the calces or oxydes of metals, externally applied, greatly + contribute to heal ulcers, of these are the solutions of lead and + mercury, and copper in acids, or their precipitates.</p> + + <p>Hence when wounds are to be healed by the first intention, as it is + called, it is necessary carefully to exclude the air from them. Hence we + have one cause, which prevents pulmonary ulcers from healing, which is + their being perpetually exposed to the air.</p> + + <p>Both the dark-eyed patients, which are affected with pulmonary ulcers + from deficient venous absorption, as described in Section. <a + href="#sect_XXVII_2">XXVII. 2</a>. and the light-eyed patients from + deficient lymphatic absorption, which we are now treating of, have + generally large apertures of the iris; these large pupils of the eyes are + a common mark of want of irritability; and it generally happens, that an + increase of sensibility, that is, of motions in consequence of sensation, + attends these constitutions. See Sect. <a href="#sect_XXXI_2">XXXI. + 2</a>. Whence inflammations may occur in these from stagnated fluids more + frequently than in those constitutions, which possess more irritability + and less sensibility.</p> + + <p>Great expectations in respect to the cure of consumptions, as well as + of many other diseases, are produced by the very ingenious exertions of + D<font class="sc">R</font>. B<font class="sc">EDDOES</font>; who has + established an apparatus for breathing various mixtures of airs or + gasses, at the hot-wells near Bristol, which well deserves the attention + of the public.</p> + + <p>D<font class="sc">R</font>. B<font class="sc">EDDOES</font> very + ingeniously concludes, from the florid colour of the blood of consumptive + patients, that it abounds in oxygene; and that the redness of their + tongues, and lips, and the fine blush of their cheeks shew the presence + of the same principle, like flesh reddened by nitre. And adds, that the + circumstance of the consumptions of pregnant women being stopped in their + progress during pregnancy, at which time their blood may be supposed to + be in part deprived of its oxygene, by oxygenating the blood of the + fœtus, is a forceable argument in favour of this theory; which must + soon be confirmed or confuted by his experiments. See Essay on Scurvy, + Consumption, &c. by Dr. Beddoes. Murray. London. Also Letter to Dr. + Darwin, by the same. Murray. London.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXIX">XXIX</a>.</h3> + +<p class="center" style="margin-top: 2em;">ON THE RETROGRADE MOTIONS OF THE ABSORBENT SYSTEM.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXIX_1">I</a>. <i>Account of the absorbent system.</i> + <a href="#sect_XXIX_2">II</a>. <i>The valves of the absorbent vessels may + suffer their fluids to regurgitate in some diseases.</i> <a + href="#sect_XXIX_3">III</a>. <i>Communication from the alimentary canal + to the bladder by means of the absorbent vessels.</i> <a + href="#sect_XXIX_4">IV</a>. <i>The phenomena of diabetes explained.</i> + <a href="#sect_XXIX_5">V</a>. <a href="#sect_XXIX_5_1">1</a>. <i>The + phenomena of dropsies explained.</i> <a href="#sect_XXIX_5_2">2</a>. + <i>Cases of the use of foxglove.</i> <a href="#sect_XXIX_6">VI</a>. <i>Of + cold sweats.</i> <a href="#sect_XXIX_7">VII</a>. <i>Translations of + matter, of chyle, of milk, of urine, operation of purging drugs applied + externally.</i> <a href="#sect_XXIX_8">VIII</a>. <i>Circumstances by + which the fluids, that are effused by the retrograde motions of the + absorbent vessels, are distinguished.</i> <a href="#sect_XXIX_9">IX</a>. + <i>Retrograde motions of vegetable juices.</i> <a + href="#sect_XXIX_10">X</a>. <i>Objections answered.</i> <a + href="#sect_XXIX_11">XI</a>. <i>The causes, which induce the retrograde + motions of animal vessels, and the medicines by which the natural motions + are restored.</i></p> + + <p><i>N.B. The following Section is a translation of a part of a Latin + thesis written by the late Mr. Charles Darwin, which was printed with his + prize-dissertation on a criterion between matter and mucus in 1780. Sold + by Cadell, London.</i></p> + +</blockquote> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_1">I</a>. <i>Account of the Absorbent System.</i></p> + + <p><a name="sect_XXIX_1_1">1</a>. The absorbent system of vessels in + animal bodies consists of several branches, differing in respect to their + situations, and to the fluids, which they absorb.</p> + + <p>The intestinal absorbents open their mouths on the internal surfaces + of the intestines; their office is to drink up the chyle and the other + fluids from the alimentary canal; and they are termed lacteals, to + distinguish them from the other absorbent vessels, which have been termed + lymphatics.</p> + + <p>Those, whose mouths are dispersed on the external skin, imbibe a great + quantity of water from the atmosphere, and a part of the perspirable + matter, which does not evaporate, and are termed cutaneous + absorbents.</p> + + <p>Those, which arise from the internal surface of the bronchia, and + which imbibe moisture from the atmosphere, and a part of the bronchial + mucus, are called pulmonary absorbents.</p> + + <p>Those, which open their innumerable mouths into the cells of the whole + cellular membrane; and whose use is to take up the fluid, which is poured + into those cells, after it has done its office there; may be called + cellular absorbents.</p> + + <p>Those, which arise from the internal surfaces of the membranes, which + line the larger cavities of the body, as the thorax, abdomen, scrotum, + pericardium, take up the mucus poured into those cavities; and are + distinguished by the names of their respective cavities.</p> + + <p>Whilst those, which arise from the internal surfaces of the urinary + bladder, gall-bladder, salivary ducts, or other receptacles of secreted + fluids, may take their names from those fluids; the thinner parts of + which it is their office to absorb: as urinary, bilious, or salivary + absorbents.</p> + + <p><a name="sect_XXIX_1_2">2</a>. Many of these absorbent vessels, both + lacteals and lymphatics, like some of the veins, are replete with valves: + which seem designed to assist the progress of their fluids, or at least + to prevent their regurgitation; where they are subjected to the + intermitted pressure of the muscular, or arterial actions in their + neighbourhood.</p> + + <p>These valves do not however appear to be necessary to all the + absorbents, any more than to all the veins; since they are not found to + exist in the absorbent system of fish; according to the discoveries of + the ingenious, and much lamented Mr. Hewson. Philos. Trans. v. 59, + Enquiries into the Lymph. Syst. p. 94.</p> + + <p><a name="sect_XXIX_1_3">3</a>. These absorbent vessels are also + furnished with glands, which are called conglobate glands; whose use is + not at present sufficiently investigated; but it is probable that they + resemble the conglomerate glands both in structure and in use, except + that their absorbent mouths are for the conveniency of situation placed + at a greater distance from the body of the gland. The conglomerate glands + open their mouths immediately into the sanguiferous vessels, which bring + the blood, from whence they absorb their respective fluids, quite up to + the gland: but these conglobate glands collect their adapted fluids from + very distant membranes, or cysts, by means of mouths furnished with long + necks for this purpose; and which are called lacteals, or lymphatics.</p> + + <p><a name="sect_XXIX_1_4">4</a>. The fluids, thus collected from various + parts of the body, pass by means of the thoracic duct into the left + subclavian near the jugular vein; except indeed that those collected from + the right side of the head and neck, and from the right arm, are carried + into the right subclavian vein: and sometimes even the lymphatics from + the right side of the lungs are inserted into the right subclavian vein; + whilst those of the left side of the head open but just into the summit + of the thoracic duct.</p> + + <p><a name="sect_XXIX_1_5">5</a>. In the absorbent system there are many + anastomoses of the vessels, which seem of great consequence to the + preservation of health. These anastomoses are discovered by dissection to + be very frequent between the intestinal and urinary lymphatics, as + mentioned by Mr. Hewson, (Phil. Trans. v. 58.)</p> + + <p><a name="sect_XXIX_1_6">6</a>. Nor do all the intestinal absorbents + seem to terminate in the thoracic duct, as appears from some curious + experiments of D. Munro, who gave madder to some animals, having + previously put a ligature on the thoracic duct, and found their bones, + and the serum of their blood, coloured red.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_2">II</a>. <i>The Valves of the Absorbent System may suffer their Fluids to +regurgitate in some Diseases.</i></p> + + <p><a name="sect_XXIX_2_1">1</a>. The many valves, which occur in the + progress of the lymphatic and lacteal vessels, would seem insuperable + obstacles to the regurgitation of their contents. But as these valves are + placed in vessels, which are indued with life, and are themselves indued + with life also; and are very irritable into those natural motions, which + absorb, or propel the fluids they contain; it is possible, in some + diseases, where these valves or vessels are stimulated into unnatural + exertions, or are become paralytic, that during the diastole of the part + of the vessel to which the valve is attached, the valve may not so + completely close, as to prevent the relapse of the lymph or chyle. This + is rendered more probable, by the experiments of injecting mercury, or + water, or suet, or by blowing air down these vessels: all which pass the + valves very easily, contrary to the natural course of their fluids, when + the vessels are thus a little forcibly dilated, as mentioned by Dr. + Haller, Elem. Physiol. t. iii. s. 4.</p> + + <p>"The valves of the thoracic duct are few, some assert they are not + more than twelve, and that they do not very accurately perform their + office, as they do not close the whole area of the duct, and thence may + permit chyle to repass them downwards. In living animals, however, though + not always, yet more frequently than in the dead, they prevent the chyle + from returning. The principal of these valves is that, which presides + over the insertion of the thoracic duct, into the subclavian vein; many + have believed this also to perform the office of a valve, both to admit + the chyle into the vein, and to preclude the blood from entering the + duct; but in my opinion it is scarcely sufficient for this purpose." + Haller, Elem. Phys. t. vii. p. 226.</p> + + <p><a name="sect_XXIX_2_2">2</a>. The mouths of the lymphatics seem to + admit water to pass through them after death, the inverted way, easier + than the natural one; since an inverted bladder readily lets out the + water with which it is filled; whence it may be inferred, that there is + no obstacle at the mouths of these vessels to prevent the regurgitation + of their contained fluids.</p> + + <p>I was induced to repeat this experiment, and having accurately tied + the ureters and neck of a fresh ox's bladder, I made an opening at the + fundus of it; and then, having turned it inside outwards, filled it half + full with water, and was surprised to see it empty itself so hastily. I + thought the experiment more apposite to my purpose by suspending the + bladder with its neck downwards, as the lymphatics are chiefly spread + upon this part of it, as shewn by Dr. Watson, Philos. Trans. v. 59. p. + 392.</p> + + <p><a name="sect_XXIX_2_3">3</a>. In some diseases, as in the diabetes + and scrophula, it is probable the valves themselves are diseased, and are + thence incapable of preventing the return of the fluids they should + support. Thus the valves of the aorta itself have frequently been found + schirrous, according to the dissections of Mons. Lieutaud, and have given + rise to an interrupted pulse, and laborious palpitations, by suffering a + return of part of the blood into the heart. Nor are any parts of the body + so liable to schirrosity as the lymphatic glands and vessels, insomuch + that their schirrosities have acquired a distinct name, and been termed + scrophula.</p> + + <p><a name="sect_XXIX_2_4">4</a>. There are valves in other parts of the + body, analogous to those of the absorbent system, and which are liable, + when diseased, to regurgitate their contents: thus the upper and lower + orifices of the stomach are closed by valves, which, when too great + quantities of warm water have been drank with a design to promote + vomiting, have sometimes resisted the utmost efforts of the abdominal + muscles, and diaphragm: yet, at other times, the upper valve, or cardia, + easily permits the evacuation of the contents of the stomach; whilst the + inferior valve, or pylorus, permits the bile, and other contents of the + duodenum, to regurgitate into the stomach.</p> + + <p><a name="sect_XXIX_2_5">5</a>. The valve of the colon is well adapted + to prevent the retrograde motion of the excrements; yet, as this valve is + possessed of a living power, in the iliac passion, either from spasm, or + other unnatural exertions, it keeps itself open, and either suffers or + promotes the retrograde movements of the contents of the intestines + below; as in ruminating animals the mouth of the first stomach seems to + be so constructed, as to facilitate or assist the regurgitation of the + food; the rings of the œsophagus afterwards contracting themselves + in inverted order. De Haeu, by means of a syringe, forced so much water + into the rectum intestinum of a dog, that he vomited it in a full stream + from his mouth; and in the iliac passion above mentioned, excrements and + clyster are often evacuated by the mouth. See Section <a + href="#sect_XXV_15">XXV. 15</a>.</p> + + <p><a name="sect_XXIX_2_6">6</a>. The puncta lacrymalia, with the + lacrymal sack and nasal duct, compose a complete gland, and much resemble + the intestinal canal: the puncta lacrymalia are absorbent mouths, that + take up the tears from the eye, when they have done their office there, + and convey them into the nostrils; but when the nasal duct is obstructed, + and the lacrymal sack distended with its fluid, on pressure with the + finger the mouths of this gland (puncta lacrymalia) will readily disgorge + the fluid, they had previously absorbed, back into the eye.</p> + + <p><a name="sect_XXIX_2_7">7</a>. As the capillary vessels receive blood + from the arteries, and separating the mucus, or perspirable matter from + it, convey the remainder back by the veins; these capillary vessels are a + set of glands, in every respect similar to the secretory vessels of the + liver, or other large congeries of glands. The beginnings of these + capillary vessels have frequent anastomoses into each other, in which + circumstance they are resembled by the lacteals; and like the mouths or + beginnings of other glands, they are a set of absorbent vessels, which + drink up the blood which is brought to them by the arteries, as the chyle + is drank up by the lacteals: for the circulation of the blood through the + capillaries is proved to be independent of arterial impulse; since in the + blush of shame, and in partial inflammations, their action is increased, + without any increase of the motion of the heart.</p> + + <p><a name="sect_XXIX_2_8">8</a>. Yet not only the mouths, or beginnings + of these anastomosing capillaries are frequently seen by microscopes, to + regurgitate some particles of blood, during the struggles of the animal; + but retrograde motion of the blood, in the veins of those animals, from + the very heart of the extremity of the limbs, is observable, by + intervals, during the distresses of the dying creature. Haller, Elem. + Physiol. t. i. p. 216. Now, as the veins have perhaps all of them a valve + somewhere between their extremities and the heart, here is ocular + demonstration of the fluids in this diseased condition of the animal, + repassing through venous valves: and it is hence highly probable, from + the strictest analogy, that if the course of the fluids, in the lymphatic + vessels, could be subjected to microscopic observation, they would also, + in the diseased state of the animal, be seen to repass the valves, and + the mouths of those vessels, which had previously absorbed them, or + promoted their progression.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_3">III</a>. <i>Communication from the Alimentary Canal to the Bladder, by +means of the Absorbent Vessels.</i></p> + + <p>Many medical philosophers, both ancient and modern, have suspected + that there was a nearer communication between the stomach and the urinary + bladder, than that of the circulation: they were led into this opinion + from the great expedition with which cold water, when drank to excess, + passes off by the bladder; and from the similarity of the urine, when + produced in this hasty manner, with the material that was drank.</p> + + <p>The former of these circumstances happens perpetually to those who + drink abundance of cold water, when they are much heated by exercise, and + to many at the beginning of intoxication.</p> + + <p>Of the latter, many instances are recorded by Etmuller, t. xi. p. 716. + where simple water, wine, and wine with sugar, and emulsions, were + returned by urine unchanged.</p> + + <p>There are other experiments, that seem to demonstrate the existence of + another passage to the bladder, besides that through the kidneys. Thus + Dr. Kratzenstein put ligatures on the ureters 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, (Disputat. Morbor. Halleri. t. iv. p. 63.) + A similar experiment is related in the Philosophical Transactions, with + the same event, (No. 65, 67, for the year 1670.)</p> + + <p>Add to this, that in some morbid cases the urine has continued to + pass, after the suppuration or total destruction of the kidneys; of which + many instances are referred to in the Elem. Physiol. t. vii. p. 379. of + Dr. Haller.</p> + + <p>From all which it must be concluded, that some fluids have passed from + the stomach or abdomen, without having gone through the sanguiferous + circulation: and as the bladder is supplied with many lymphatics, as + described by Dr. Watson, in the Philos. Trans. v. 59. p. 392. and as no + other vessels open into it besides these and the ureters, it seems + evident, that the unnatural urine, produced as above described, when the + ureters were tied, or the kidneys obliterated, was carried into the + bladder by the retrograde motions of the urinary branch of the lymphatic + system.</p> + + <p>The more certainly to ascertain the existence of another communication + between the stomach and bladder, besides that of the circulation, the + following experiment was made, to which I must beg your patient + attention:—A friend of mine (June 14, 1772) on drinking repeatedly + of cold small punch, till he began to be intoxicated, made a quantity of + colourless urine. He then drank about two drams of nitre dissolved in + some of the punch, and eat about twenty stalks of boiled asparagus: on + continuing to drink more of the punch, the next urine that he made was + quite clear, and without smell; but in a little time another quantity was + made, which was not quite so colourless, and had a strong smell of the + asparagus: he then lost about four ounces of blood from the arm.</p> + + <p>The smell of asparagus was not at all perceptible in the blood, + neither when fresh taken, nor the next morning, as myself and two others + accurately attended to; yet this smell was strongly perceived in the + urine, which was made just before the blood was taken from his arm.</p> + + <p>Some bibulous paper, moistened in the serum of this blood, and + suffered to dry, shewed no signs of nitre by its manner of burning. But + some of the same paper, moistened in the urine, and dried, on being + ignited, evidently shewed the presence of nitre. This blood and the urine + stood some days exposed to the sun in the open air, till they were + evaporated to about a fourth of their original quantity, and began to + stink: the paper, which was then moistened with the concentrated urine, + shewed the presence of much nitre by its manner of burning; whilst that + moistened with the blood shewed no such appearance at all.</p> + + <p>Hence it appears, that certain fluids at the beginning of + intoxication, find another passage to the bladder besides the long course + of the arterial circulation; and as the intestinal absorbents are joined + with the urinary lymphatics by frequent anastomoses, as Hewson has + demonstrated; and as there is no other road, we may justly conclude, that + these fluids pass into the bladder by the urinary branch of the + lymphatics, which has its motions inverted during the diseased state of + the animal.</p> + + <p>A gentleman, who had been some weeks affected with jaundice, and whose + urine was in consequence of a very deep yellow, took some cold small + punch, in which was dissolved about a dram of nitre; he then took + repeated draughts of the punch, and kept himself in a cool room, till on + the approach of slight intoxication he made a large quantity of water; + this water had a slight yellow tinge, as might be expected from a small + admixture of bile secreted from the kidneys; but if the whole of it had + passed through the sanguiferous vessels, which were now replete with bile + (his whole skin being as yellow as gold) would not this urine also, as + well as that he had made for weeks before, have been of a deep yellow? + Paper dipped in this water, and dryed, and ignited, shewed evident marks + of the presence of nitre, when the flame was blown out.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_4">IV</a>. <i>The Phænomena of the Diabetes explained, and of some Diarrhœas.</i></p> + + <p>The phenomena of many diseases are only explicable from the retrograde + motions of some of the branches of the lymphatic system; as the great and + immediate flow of pale urine in the beginning of drunkenness; in hysteric + paroxysms; from being exposed to cold air; or to the influence of fear or + anxiety.</p> + + <p>Before we endeavour to illustrate this doctrine, by describing the + phænomena of these diseases, we must premise one circumstance; that all + the branches of the lymphatic system have a certain sympathy with each + other, insomuch that when one branch is stimulated into unusual kinds or + quantities of motion, some other branch has its motions either increased, + or decreased, or inverted at the same time. This kind of sympathy can + only be proved by the concurrent testimony of numerous facts, which will + be related in the course of the work. I shall only add here, that it is + probable, that this sympathy does not depend on any communication of + nervous filaments, but on habit; owing to the various branches of this + system having frequently been stimulated into action at the same + time.</p> + + <p>There are a thousand instances of involuntary motions associated in + this manner; as in the act of vomiting, while the motions of the stomach + and œsophagus are inverted, the pulsations of the arterial system by + a certain sympathy become weaker; and when the bowels or kidneys are + stimulated by poison, a stone, or inflammation, into more violent action; + the stomach and œsophagus by sympathy invert their motions.</p> + + <p><a name="sect_XXIX_4_1">1</a>. When any one drinks a moderate quantity + of vinous spirit, the whole system acts with more energy by consent with + the stomach and intestines, as is seen from the glow on the skin, and the + increase of strength and activity; but when a greater quantity of this + inebriating material is drank, at the same time that the lacteals are + excited into greater action to absorb it; it frequently happens, that the + urinary branch of absorbents, which is connected with the lacteals by + many anastomoses, inverts its motions, and a great quantity of pale + unanimalized urine is discharged. By this wise contrivance too much of an + unnecessary fluid is prevented from entering the circulation—This + may be called the drunken diabetes, to distinguish it from the other + temporary diabetes, which occur in hysteric diseases, and from continued + fear or anxiety.</p> + + <p><a name="sect_XXIX_4_2">2</a>. If this idle ingurgitation of too much + vinous spirit be daily practised, the urinary branch of absorbents at + length gains an habit of inverting its motions, whenever the lacteals are + much stimulated; 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 diabetes, and may be + distinguished from the others by the taste and appearance of the urine; + which is sweet, and the colour of whey, and may be termed the chyliferous + diabetes.</p> + + <p><a name="sect_XXIX_4_3">3</a>. Many children have a similar deposition + of chyle in their urine, from the irritation of worms in their + intestines, which stimulating the mouths of the lacteals into unnatural + action, the urinary branch of the absorbents becomes inverted, and + carries part of the chyle to the bladder: part of the chyle also has been + carried to the iliac and lumbar glands, of which instances are recorded + by Haller, t. vii. 225. and which can be explained on no other theory: + but the dissections of the lymphatic system of the human body, which have + yet been published, are not sufficiently extensive for our purpose; yet + if we may reason from comparative anatomy, this translation of chyle to + the bladder is much illustrated by the account given of this system of + vessels in a turtle, by Mr. Hewson, who observed, "That the lacteals near + the root of the mesentery anastomose, so as to form a net-work, from + which several large branches go into some considerable lymphatics lying + near the spine; and which can be traced almost to the anus, and + particularly to the kidneys." Philos. Trans. v. 59. p. + 199—Enquiries, p. 74.</p> + + <p><a name="sect_XXIX_4_4">4</a>. At the same time that the urinary + branch of absorbents, in the beginning of diabetes, is excited into + inverted action, the cellular branch is excited by the sympathy above + mentioned, into more energetic action; and the fat, that was before + deposited, is reabsorbed and thrown into the blood vessels; where it + floats, and was mistaken for chyle, till the late experiments of the + ingenious Mr. Hewson demonstrated it to be fat.</p> + + <p>This appearance of what was mistaken for chyle in the blood, which was + drawn from these patients, and the obstructed liver, which very + frequently accompanies this disease, seems to have led Dr. Mead to + suspect the diabetes was owing to a defect of sanguification; and that + the schirrosity of the liver was the original cause of it: but as the + schirrhus of the liver is most frequently owing to the same causes, that + produce the diabetes and dropsies; namely, the great use of fermented + liquors; there is no wonder they should exist together, without being the + consequence of each other.</p> + + <p><a name="sect_XXIX_4_5">5</a>. If the cutaneous branch of absorbents + gains a habit of being excited into stronger action, and imbibes greater + quantities of moisture from the atmosphere, at the same time that the + urinary branch has its motions inverted, another kind of diabetes is + formed, which may be termed the aqueous diabetes. In this diabetes the + cutaneous absorbents frequently imbibe an amazing quantity of atmospheric + moisture; insomuch that there are authentic histories, where many gallons + a day, for many weeks together, above the quantity that has been drank, + have been discharged by urine.</p> + + <p>Dr. Keil, in his Medicina Statica, found that he gained eighteen + ounces from the moist 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. (Transact. of the College, London, + vol. ii. p. 102.) Home's Medic. Facts, p. 2. sect. 3.</p> + + <p>The pale urine in hysterical women, or which is produced by fear or + anxiety, is a temporary complaint of this kind; and it would in reality + be the same disease, if it was confirmed by habit.</p> + + <p><a name="sect_XXIX_4_6">6</a>. The purging stools, and pale urine, + occasioned by exposing the naked body to cold air, or sprinkling it with + cold water, originate from a similar cause; for the mouths of the + cutaneous lymphatics being suddenly exposed to cold become torpid, and + cease, or nearly cease, to act; whilst, by the sympathy above described, + not only the lymphatics of the bladder and intestines cease also to + absorb the more aqueous and saline part of the fluids secreted into them; + but it is probable that these lymphatics invert their motions, and return + the fluids, which were previously absorbed, into the intestines and + bladder. At the very instant that the body is exposed naked to the cold + air, an unusual movement is felt in the bowels; as is experienced by boys + going into the cold bath: this could not occur from an obstruction of the + perspirable matter, since there is not time, for that to be returned to + the bowels by the course of the circulation.</p> + + <p>There is also a chronic aqueous diarrhœa, in which the + atmospheric moisture, drank up by the cutaneous and pulmonary lymphatics, + is poured into the intestines, by the retrograde motions of the lacteals. + This disease is most similar to the aqueous diabetes, and is frequently + exchanged for it: a distinct instance of this is recorded by Benningerus, + Cent. v. Obs. 98. in which an aqueous diarrhœa succeeded an aqueous + diabetes, and destroyed the patient. There is a curious example of this, + described by Sympson (De Re Medica)—"A young man (says he) was + seized with a fever, upon which a diarrhœa came on, with great + stupor; and he refused to drink any thing, though he was parched up with + excessive heat: the better to supply him with moisture, I directed his + feet to be immersed in cold water; immediately I observed a wonderful + decrease of water in the vessel, and then an impetuous stream of a fluid, + scarcely coloured, was discharged by stool, like a cataract."</p> + + <p><a name="sect_XXIX_4_7">7</a>. There is another kind of diarrhœa, + which has been called cæliaca; in this disease the chyle, drank up by the + lacteals of the small intestines, is probably poured into the large + intestines, 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 urinary branch of absorbents.</p> + + <p>The chyliferous diabetes, like this chyliferous diarrhœa, + produces sudden atrophy; since the nourishment, which ought to supply the + hourly waste of the body, is expelled by the bladder, or rectum: whilst + the aqueous diabetes, and the aqueous diarrhœa produce excessive + thirst; because the moisture, which is obtained from the atmosphere, is + not conveyed to the thoracic receptacle, as it ought to be, but to the + bladder, or lower intestines; whence the chyle, blood, and whole system + of glands, are robbed of their proportion of humidity.</p> + + <p><a name="sect_XXIX_4_8">8</a>. There is a third species of diabetes, + in which the urine is mucilaginous, and appears ropy in pouring it from + one vessel into another; and will sometimes coagulate over the fire. This + disease appears by intervals, and ceases again, and seems to be + occasioned by a previous dropsy in some part of the body. When such a + collection is reabsorbed, it is not always returned into the circulation; + but the same irritation that stimulates one lymphatic branch to reabsorb + the deposited fluid, inverts the urinary branch, and pours it into the + bladder. Hence this mucilaginous diabetes is a cure, or the consequence + of a cure, of a worse disease, rather than a disease itself.</p> + + <p>Dr. Cotunnius gave half an ounce of cream of tartar, every morning, to + a patient, who had the anasarca; and he voided a great quantity of urine; + a part of which, put over the fire, coagulated, on the evaporation of + half of it, so as to look like the white of an egg. De Ischiade + Nervos.</p> + + <p>This kind of diabetes frequently precedes a dropsy; and has this + remarkable circumstance attending it, that it generally happens in the + night; as during the recumbent state of the body, the fluid, that was + accumulated in the cellular membrane, or in the lungs, is more readily + absorbed, as it is less impeded by its gravity. I have seen more than one + instance of this disease. Mr. D. a man in the decline of life, who had + long accustomed himself to spirituous liquor, had swelled legs, and other + symptoms of approaching anasarca; about once in a week, or ten days, for + several months, he was seized, on going to bed, with great general + uneasiness, which his attendants resembled to an hysteric fit; and which + terminated in a great discharge of viscid urine; his legs became less + swelled, and he continued in better health for some days afterwards. I + had not the opportunity to try if 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; as the mucilaginous fluid deposited + in the cells and cysts of the body, which have no communication with the + external air, seems to acquire, by stagnation, this property of + coagulation by heat, which the secreted mucus of the intestines and + bladder do not appear to possess; as I have found by experiment: and if + any one should suppose this coagulable urine was separated from the blood + by the kidneys, he may recollect, that in the most inflammatory diseases, + in which the blood is most replete or most ready to part with the + coagulable lymph, none of this appears in the urine.</p> + + <p><a name="sect_XXIX_4_9">9</a>. Different kinds of diabetes require + different methods of cure. For the first kind, or chyliferous diabetes, + after clearing the stomach and intestines, by ipecacuanha and rhubarb, to + evacuate any acid material, which may too powerfully stimulate the mouths + of the lacteals, repeated and large doses of tincture of cantharides have + been much recommended. The specific stimulus of this medicine, on the + neck of the bladder, is likely to excite the numerous absorbent vessels, + which are spread on that part, into stronger natural actions, and by that + means prevent their retrograde ones; till, by persisting in the use of + the medicine, their natural habits of motions might again be established. + Another indication of cure, requires such medicines, as by lining the + intestines with mucilaginous substances, or with such as consist of + smooth particles, or which chemically destroy the acrimony of their + contents, may prevent the too great action of the intestinal absorbents. + For this purpose, I have found the earth precipitated from a solution of + alum, by means of fixed alcali, given in the dose of half a dram every + six hours, of great advantage, with a few grains of rhubarb, so as to + produce a daily evacuation.</p> + + <p>The food should consist of materials that have the least stimulus, + with calcareous water, as of Bristol and Matlock; that the mouths of the + lacteals may be as little stimulated as is necessary for their proper + absorption; lest with their greater exertions, should be connected by + sympathy, the inverted motions of the urinary lymphatics.</p> + + <p>The same method may be employed with equal advantage in the aqueous + diabetes, so great is the sympathy between the skin and the stomach. To + which, however, some application to the skin might be usefully added; as + rubbing the patient all over with oil, to prevent the too great action of + the cutaneous absorbents. I knew an experiment of this kind made upon one + patient with apparent advantage.</p> + + <p>The mucilaginous diabetes will require the same treatment, which is + most efficacious in the dropsy, and will be described below. I must add, + that the diet and medicines above mentioned, are strongly recommended by + various authors, as by Morgan, Willis, Harris, and Etmuller; but more + histories of the successful treatment of these diseases are wanting to + fully ascertain the most efficacious methods of cure.</p> + + <p>In a letter from Mr. Charles Darwin, dated April 24, 1778, Edinburgh, + is the subsequent passage:—"A man who had long laboured under a + diabetes died yesterday in the clinical ward. He had for some time drank + four, and passed twelve pounds of fluid daily; each pound of urine + contained an ounce of sugar. He took, without considerable relief, gum + kino, sanguis diaconis melted with alum, tincture of cantharides, + isinglass, gum arabic, crabs eyes, spirit of hartshorn, and eat ten or + fifteen oysters thrice a day. Dr. Home, having read my thesis, bled him, + and found that neither the fresh blood nor the serum tasted sweet. His + body was opened this morning—every viscus appeared in a sound and + natural state, except that the left kidney had a very small pelvis, and + that there was a considerable enlargement of most of the mesenteric + lymphatic glands. I intend to insert this in my thesis, as it coincides + with the experiment, where some asparagus was eaten at the beginning of + intoxication, and its smell perceived in the urine, though not in the + blood."</p> + + <p>The following case of chyliferous diabetes is extracted from some + letters of Mr. Hughes, to whose unremitted care the infirmary at Stafford + for many years was much indebted. Dated October 10, 1778.</p> + + <p>Richard Davis, aged 33, a whitesmith by trade, had drank hard by + intervals; was much troubled with sweating of his hands, which incommoded + him in his occupation, but which ceased on his frequently dipping them in + lime. About seven months ago he began to make large quantities of water; + his legs are œdematous, his belly tense, and he complains of a + rising in his throat, like the globus hystericus: he eats twice as much + as other people, drinks about fourteen pints of small beer a day, besides + a pint of ale, some milk-porridge, and a bason of broth, and he makes + about eighteen pints of water a day.</p> + + <p>He tried alum, dragon's blood, steel, blue vitriol, and cantharides 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 + cantharides, he made but twelve pints of water, but on the next day this + good effect ceased again.</p> + + <p>November 21.—He made eighteen pints of water, and he now, at Dr. + Darwin's request, took a grain of opium every four hours, and five grains + of aloes at night; and had a flannel shirt given him.</p> + + <p>22.—Made sixteen pints. 23.—Thirteen pints: drinks + less.</p> + + <p>24.—Increased the opium to a grain and quarter every four hours: + he made twelve pints.</p> + + <p>25.—Increased the opium to a grain and half: he now makes ten + pints; and drinks eight pints in a day.</p> + + <p>The opium was gradually increased during the next fortnight, till he + took three grains every four hours, but without any further diminution of + his water. During the use of the opium he sweat much in the nights, so as + to have large drops stand on his face and all over him. The quantity of + opium was then gradually decreased, but not totally omitted, as he + continued to take about a grain morning and evening.</p> + + <p>January 17.—He makes fourteen pints of water a day. Dr. + Underhill now directed him two scruples of common rosin triturated with + as much sugar, every six hours; and three grains of opium every + night.</p> + + <p>19.—Makes fifteen pints of water: sweats at night.</p> + + <p>21.—Makes seventeen pints of water; has twitchings of his limbs + in a morning, and pains of his legs: he now takes a dram of rosin for a + dose, and continues the opium.</p> + + <p>23.—Water more coloured, and reduced to sixteen pints, and he + thinks has a brackish taste.</p> + + <p>26.—Water reduced to fourteen pints.</p> + + <p>28.—Water thirteen pints: he continues the opium, and takes four + scruples of the rosin for a dose.</p> + + <p>February 1.—Water twelve pints.</p> + + <p>4.—Water eleven pints: twitchings less; takes five scruples for + a dose.</p> + + <p>8.—Water ten pints: has had many stools.</p> + + <p>12.—Appetite less: purges very much.</p> + + <p>After this the rosin either purged him, or would not stay on his + stomach; and he gradually relapsed nearly to his former condition, and in + a few months sunk under the disease.</p> + + <p>October 3, Mr. Hughes evaporated two quarts of the water, and obtained + from it four ounces and half of a hard and brittle saccharine mass, like + treacle which had been some time boiled. Four ounces of blood, which he + took from his arm with design to examine it, had the common appearances, + except that the serum resembled cheese-whey; and that on the evidence of + four persons, two of whom did not know what it was they tasted, <i>the + serum had a saltish taste</i>.</p> + + <p>From hence it appears, that the saccharine matter, with which the + urine of these patients so much abounds, does not enter the blood-vessels + like the nitre and asparagus mentioned above; but that the process of + digestion resembles the process of the germination of vegetables, or of + making barley into malt; as the vast quantity of sugar found in the urine + must be made from the food which he took (which was double that taken by + others), and from the fourteen pints of small beer which he drank. And, + secondly, as the serum of the blood was not sweet, the chyle appears to + have been conveyed to the bladder without entering the circulation of the + blood, since so large a quantity of sugar, as was found in the urine, + namely, twenty ounces a day, could not have previously existed in the + blood without being perceptible to the taste.</p> + + <p>November 1. Mr. Hughes dissolved two drams of nitre in a pint of a + decoction of the roots of asparagus, 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 manifestly tinged with the + rhubarb; the smell of asparagus was doubtful.</p> + + <p>He then lost four ounces of blood, the serum of which was not so opake + as that drawn before, but of a yellowish cast, as the serum of the blood + usually appears.</p> + + <p>Paper, dipped three or four times in the tinged urine and dried again, + did not scintillate when it was set on fire; but when the flame was blown + out, the fire ran along the paper for half an inch; which, when the same + paper was unimpregnated, it would not do; nor when the same paper was + dipped in urine made before he took the nitre, and dried in the same + manner.</p> + + <p>Paper, dipped in the serum of the blood and dried in the same manner + as in the urine, did not scintillate when the flame was blown out, but + burnt exactly in the same manner as the same paper dipped in the serum of + blood drawn from another person.</p> + + <p>This experiment, which is copied from a letter of Mr. Hughes, as well + as the former, seems to evince the existence of another passage from the + intestines to the bladder, in this disease, besides that of the + sanguiferous system; and coincides with the curious experiment related in + section the third, except that the smell of the asparagus was not here + perceived, owing perhaps to the roots having been made use of instead of + the heads.</p> + + <p>The rising in the throat of this patient, and the twitchings of his + limbs, seem to indicate some similarity between the diabetes and the + hysteric disease, besides the great flow of pale urine, which is common + to them both.</p> + + <p>Perhaps if the mesenteric glands were nicely inspected in the + dissections of these patients; and if the thoracic duct, and the larger + branches of the lacteals, and if the lymphatics, which arise from the + bladder, were well examined by injection, or by the knife, the cause of + diabetes might be more certainly understood.</p> + + <p>The opium alone, and the opium with the rosin, seem much to have + served this patient, and might probably have effected a cure, if the + disease had been slighter, or the medicine had been exhibited, before it + had been confirmed by habit during the seven months it had continued. The + increase of the quantity of water on beginning the large doses of rosin + was probably owing to his omitting the morning doses of opium.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_5">V</a>. <i>The Phænomena of Dropsies explained.</i></p> + + <p><a name="sect_XXIX_5_1">I</a>. Some inebriates have their paroxysms of + inebriety terminated by much pale urine, or profuse sweats, or vomiting, + or stools; others have their paroxysms terminated by stupor, or sleep, + without the above evacuations.</p> + + <p>The former kind of these inebriates have been observed to be more + liable to diabetes and dropsy; and the latter to gout, gravel, and + leprosy. Evoe! attend ye bacchanalians! start at this dark train of + evils, and, amid your immodest jests, and idiot laughter, recollect,</p> + + <div class="poem"> + <div class="stanza"> + <p>Quem Deus vult perdere, prius dementat.</p> + </div> + </div> + <p>In those who are subject to diabetes and dropsy, the absorbent vessels + are naturally more irritable than in the latter; and by being frequently + disturbed or inverted by violent stimulus, and by their too great + sympathy with each other, they become at length either entirely + paralytic, or are only susceptible of motion from the stimulus of very + acrid materials; as every part of the body, after having been used to + great irritations, becomes less affected by smaller ones. Thus we cannot + distinguish objects in the night, for some time after we come out of a + strong light, though the iris is presently dilated; and the air of a + summer evening appears cold, after we have been exposed to the heat of + the day.</p> + + <p>There are no cells in the body, where dropsy may not be produced, if + the lymphatics cease to absorb that mucilaginous fluid, which is + perpetually deposited in them, for the purpose of lubricating their + surfaces.</p> + + <p>If the lymphatic branch, which opens into the cellular membrane, + either does its office imperfectly, or not at all; these cells become + replete with a mucilaginous fluid, which, after it has stagnated some + time in the cells, will coagulate over the fire; and is erroneously + called water. Wherever the seat of this disease is, (unless in the lungs + or other pendent viscera) the mucilaginous liquid above mentioned will + subside to the most depending parts of the body, as the feet and legs, + when those are lower than the head and trunk; for all these cells have + communications with each other.</p> + + <p>When the cellular absorbents are become insensible to their usual + irritations, it most frequently happens, but not always, that the + cutaneous branch of absorbents, which is strictly associated with them, + suffers the like inability. And then, as no water is absorbed from the + atmosphere, the urine is not only less diluted at the time of its + secretion, and consequently in less quantity and higher coloured: but + great thirst is at the same time induced, for as no water is absorbed + from the atmosphere to dilute the chyle and blood, the lacteals and other + absorbent vessels, which have not lost their powers, are excited into + more constant or more violent action, to supply this deficiency; whence + the urine becomes still less in quantity, and of a deeper colour, and + turbid like the yolk of an egg, owing to a greater absorption of its + thinner parts. From this stronger action of those absorbents, which still + retain their irritability, the fat is also absorbed, and the whole body + becomes emaciated. This increased exertion of some branches of the + lymphatics, while others are totally or partially paralytic, is resembled + by what constantly occurs in the hemiplagia; when the patient has lost + the use of the limbs on one side, he is incessantly moving those of the + other; for the moving power, not having access to the paralytic limbs, + becomes redundant in those which are not diseased.</p> + + <p>The paucity of urine and thirst cannot be explained from a greater + quantity of mucilaginous fluid being deposited in the cellular membrane: + for though these symptoms have continued many weeks, or even months, this + collection frequently does not amount to more than very few pints. Hence + also the difficulty of promoting copious sweats in anasarca is accounted + for, as well as the great thirst, paucity of urine, and loss of fat; + since, when the cutaneous branch of absorbents is paralytic, or nearly + so, there is already too small a quantity of aqueous fluid in the blood: + nor can these torpid cutaneous lymphatics be readily excited into + retrograde motions.</p> + + <p>Hence likewise we understand, why in the ascites, and some other + dropsies, there is often no thirst, and no paucity of urine; in these + cases the cutaneous absorbents continue to do their office.</p> + + <p>Some have believed, that dropsies were occasioned by the inability of + the kidneys, from having only observed the paucity of urine; and have + thence laboured much to obtain diuretic medicines; but it is daily + observable, that those who die of a total inability to make water, do not + become dropsical in consequence of it: Fernelius mentions one, who + laboured under a perfect suppression of urine during twenty days before + his death, and yet had no symptoms of dropsy. Pathol. 1. vi. c. 8. From + the same idea many physicians have restrained their patients from + drinking, though their thirst has been very urgent; and some cases have + been published, where this cruel regimen has been thought advantageous: + but others of nicer observation are of opinion, that it has always + aggravated the distresses of the patient; and though it has abated his + swellings, yet by inducing a fever it has hastened his dissolution. See + Transactions of the College, London, vol. ii. p. 235. Cases of Dropsy by + Dr. G. Baker.</p> + + <p>The cure of anasarca, so far as respects the evacuation of the + accumulated fluid, coincides with the idea of the retrograde action of + the lymphatic system. It is well known that vomits, and other drugs, + which induce sickness or nausea; at the same time that they evacuate the + stomach, produce a great absorption of the lymph accumulated in the + cellular membrane. In the operation of a vomit, not only the motions of + the stomach and duodenum become inverted, but also those of the + lymphatics and lacteals, which belong to them; whence a great quantity of + chyle and lymph is perpetually poured into the stomach and intestines, + during the operation, and evacuated by the mouth. Now at the same time, + other branches of the lymphatic system, viz. those which open on the + cellular membrane, are brought into more energetic action, by the + sympathy above mentioned, and an increase of their absorption is + produced.</p> + + <p>Hence repeated vomits, and cupreous salts, and small doses of squill + or foxglove, are so efficacious in this disease. And as drastic purges + act also by inverting the motions of the lacteals; and thence the other + branches of lymphatics are induced into more powerful natural action, by + sympathy, and drink up the fluids from all the cells of the body; and by + their anastomoses, pour them into the lacteal branches; which, by their + inverted actions, return them into the intestines; and they are thus + evacuated from the body:—these purges also are used with success in + discharging the accumulated fluid in anasarca.</p> + + <p><a name="sect_XXIX_5_2">II</a>. The following cases are related with + design to ascertain the particular kinds of dropsy in which the digitalis + purpurea, or common foxglove, is preferable to squill, or other + evacuants, and were first published in 1780, in a pamphlet entitled + Experiments on mucilaginous and purulent Matter, &c. Cadell. London. + Other cases of dropsy, treated with digitalis, were afterwards published + by Dr. Darwin in the Medical Transactions, vol. iii. in which there is a + mistake in respect to the dose of the powder of foxglove, which should + have been from five grains to one, instead of from five grains to + ten.</p> + +<p class="center" style="margin-top: 2em;"><i>Anasarca of the Lungs.</i></p> + + <p>1. A lady, between forty and fifty years of age, had been indisposed + some time, was then seized with cough and fever, and afterwards + expectorated much digested mucus. This expectoration suddenly ceased, and + a considerable difficulty of breathing supervened, with a pulse very + irregular both in velocity and strength; she was much distressed at first + lying down, and at first rising; but after a minute or two bore either of + those attitudes with ease. She had no pain or numbness in her arms; she + had no hectic fever, nor any cold shiverings, and the urine was in due + quantity, and of the natural colour.</p> + + <p>The difficulty of breathing was twice considerably relieved by small + doses of ipecacuanha, which operated upwards and downwards, but recurred + in a few days: she was then directed a decoction of foxglove, (digitalis + purpurea) prepared by boiling four ounces of the fresh leaves from two + pints of water to one pint; to which was added two ounces of vinous + spirit: she took three large spoonfuls of this mixture every two hours, + till she had taken it four times; a continued sickness supervened, with + frequent vomiting, and a copious flow of urine: these evacuations + continued at intervals for two or three days, and relieved the difficulty + of breathing—She had some relapses afterwards, which were again + relieved by the repetition of the decoction of foxglove.</p> + + <p>2. A gentleman, about sixty years of age, who had been addicted to an + immoderate use of fermented liquors, and had been very corpulent, + gradually lost his strength and flesh, had great difficulty of breathing, + with legs somewhat swelled, and a very irregular pulse. He was very much + distressed at first lying down, and at first rising from his bed, yet in + a minute or two was easy in both those attitudes. He made straw-coloured + urine in due quantity, and had no pain or numbness of his arms.</p> + + <p>He took a large spoonful of the decoction of foxglove, as above, every + hour, for ten or twelve successive hours, had incessant sickness for + about two days, and passed a large quantity of urine; upon which his + breath became quite easy, and the swelling of his legs subsided; but as + his whole constitution was already sinking from the previous intemperance + of his life, he did not survive more than three or four months.</p> + +<p class="center" style="margin-top: 2em;"><i>Hydrops Pericardii.</i></p> + + <p>3. A gentleman of temperate life and sedulous application to business, + between thirty and forty years of age, had long been subject, at + intervals, to an irregular pulse: a few months ago he became weak, with + difficulty of breathing, and dry cough. In this situation a physician of + eminence directed him to abstain from all animal food and fermented + liquor, during which regimen all his complaints increased; he now became + emaciated, and totally lost his appetite; his pulse very irregular both + in velocity and strength; with great difficulty of breathing, and some + swelling of his legs; yet he could lie down horizontally in his bed, + though he got little sleep, and passed a due quantity of urine, and of + the natural colour: no fullness or hardness could be perceived about the + region of the liver; and he had no pain or numbness in his arms.</p> + + <p>One night he had a most profuse sweat all over his body and limbs, + which quite deluged his bed, and for a day or two somewhat relieved his + difficulty of breathing, and his pulse became less irregular: this + copious sweat recurred three or four times at the intervals of five or + six days, and repeatedly alleviated his symptoms.</p> + + <p>He was directed one large spoonful of the above decoction of foxglove + every hour, till it procured some considerable evacuation: after he had + taken it eleven successive hours he had a few liquid stools, attended + with a great flow of urine, which last had a dark tinge, as if mixed with + a few drops of blood: he continued sick at intervals for two days, but + his breath became quite easy, and his pulse quite regular, the swelling + of his legs disappeared, and his appetite and sleep returned.</p> + + <p>He then took three grains of white vitriol twice a day, with some + bitter medicines, and a grain of opium with five grains of rhubarb every + night; was advised to eat flesh meat, and spice, as his stomach would + bear it, with small beer, and a few glasses of wine; and had issues made + in his thighs; and has suffered no relapse.</p> + + <p>4. A lady, about fifty years of age, had for some weeks great + difficulty of breathing, with very irregular pulse, and considerable + general debility: she could lie down in bed, and the urine was in due + quantity and of the natural colour, and she had no pain or numbness of + her arms.</p> + + <p>She took one large spoonful of the above decoction of foxglove every + hour, for ten or twelve successive hours; was sick, 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 pulse. She then took + a grain of opium, and five grains of rhubarb, every night, night, for + many weeks; with some slight chalybeate and bitter medicines, and has + suffered no relapse.</p> + +<p class="center" style="margin-top: 2em;"><i>Hydrops Thoracis.</i></p> + + <p>5. A tradesman, about fifty years of age, became weak and short of + breath, especially on increase of motion, with pain in one arm, about the + insertion of the biceps muscle. He observed he sometimes in the night + made an unusual quantity of pale water. He took calomel, alum, and + peruvian bark, and all his symptoms increased: his legs began to swell + considerably; his breath became more difficult, and he could not lie down + in bed; but all this time he made a due quantity of straw-coloured + water.</p> + + <p>The decoction of foxglove was given as in the preceding cases, which + operated chiefly by purging, and seemed to relieve his breath for a day + or two; but also seemed to contribute to weaken him.—He became + after some weeks universally dropsical, and died comatous.</p> + + <p>6. A young lady of delicate constitution, with light eyes and hair, + and who had perhaps lived too abstemiously both in respect to the + quantity and quality of what she eat and drank, was seized with great + difficulty of breathing, so as to threaten immediate death. Her + extremities were quite cold, and her breath felt cold to the back of + one's hand. She had no sweat, nor could be down for a single moment; and + had previously, and at present, complained of great weakness and pain and + numbness of both her arms; had no swelling of her legs, no thirst, water + in due quantity and colour. Her sister, about a year before, was + afflicted with similar symptoms, was repeatedly blooded, and died + universally dropsical.</p> + + <p>A grain of opium was given immediately, and repeated every six hours + with evident and amazing advantage; afterwards a blister, with + chalybeates, bitters, and essential oils, were exhibited, but nothing had + such eminent effect in relieving the difficulty of breathing and coldness + of her extremities as opium, by the use of which in a few weeks she + perfectly regained her health, and has suffered no relapse.</p> + +<p class="center" style="margin-top: 2em;"><i>Ascites.</i></p> + + <p>7. A young lady of delicate constitution having been exposed to great + fear, cold, and fatigue, by the overturn of a chaise in the night, began + with pain and tumour in the right hypochondrium: in a few months a + fluctuation was felt throughout the whole abdomen, more distinctly + perceptible indeed about the region of the stomach; since the integuments + of the lower part of the abdomen generally become thickened in this + disease by a degree of anasarca. Her legs were not swelled, no thirst, + water in due quantity and colour.—She took the foxglove so as to + induce sickness and stools, but without abating the swelling, and was + obliged at length to submit to the operation of tapping.</p> + + <p>8. A man about sixty-seven, who had long been accustomed to spirituous + potation, had some time laboured under ascites; his legs somewhat + swelled; his breath easy in all attitudes; no appetite; great thirst; + urine in exceedingly small quantity, very deep coloured, and turbid; + pulse equal. He took the foxglove in such quantity as vomited him, and + induced sickness for two days; but procured no flow of urine, or + diminution of his swelling; but was thought to leave him considerably + weaker.</p> + + <p>9. A corpulent man, accustomed to large potation of fermented liquors, + had vehement cough, difficult breathing, anasarca of his legs, thighs, + and hands, and considerable tumour, with evident fluctuation of his + abdomen; his pulse was equal; his urine in small quantity, of deep + colour, and turbid. These swellings had been twice considerably abated by + drastic cathartics. He took three ounces of a decoction of foxglove (made + by boiling one ounce of the fresh 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 these + evacuations completely emptied in twelve hours. After two or three months + all these symptoms returned, and were again relieved by the use of the + foxglove; and thus in the space of about three years he was about ten + times evacuated, and continued all that time his usual potations: + excepting at first, the medicine operated only by urine, and did not + appear considerably to weaken him—The last time he took it, it had + no effect; and a few weeks afterwards he vomited a great quantity of + blood, and expired.</p> + +<h3>QUERIES.</h3> + + <p>1. As the first six of these patients had a due discharge of urine, + and of the natural colour, was not the feat of the disease confined to + some part of the thorax, and the swelling of the legs rather a symptom of + the obstructed circulation of the blood, than of a paralysis of the + cellular lymphatics of those parts?</p> + + <p>2. When the original disease is a general anasarca, do not the + cutaneous lymphatics always become paralytic at the same time with the + cellular ones, by their greater sympathy with each other? and hence the + paucity of urine, and the great thirst, distinguish this kind of + dropsy?</p> + + <p>3. In the anasarca of the lungs, when the disease is not very great, + though the patients have considerable difficulty of breathing at their + first lying down, yet after a minute or two their breath becomes easy + again; and the same occurs at their first rising. Is not this owing to + the time necessary for the fluid in the cells of the lungs to change its + place, so as the least to incommode respiration in the new attitude?</p> + + <p>4. In the dropsy of the pericardium does not the patient bear the + horizontal or perpendicular attitude with equal ease? Does this + circumstance distinguish the dropsy of the pericardium from that of the + lungs and of the thorax?</p> + + <p>5. Do the universal sweats distinguish the dropsy of the pericardium, + or of the thorax? and those, which cover the upper parts of the body + only, the anasarca of the lungs?</p> + + <p>6. When in the dropsy of the thorax, the patient endeavours to lie + down, does not the extravasated fluid compress the upper parts of the + bronchia, and totally preclude the access of air to every part of the + lungs; whilst in the perpendicular attitude the inferior parts of the + lungs only are compressed? Does not something similar to this occur in + the anasarca of the lungs, when the disease is very great, and thus + prevent those patients also from lying down?</p> + + <p>7. As a principal branch of the fourth cervical nerve of the left + side, after having joined a branch of the third and of the second + 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 considerable turn outwards to go over the prominent part of it, + where the point of the heart is lodged, in its course to the diaphragm; + and as the other phrenic nerve of the right side has a straight course to + the diaphragm; and as many other considerable branches of this fourth + pair of cervical nerves are spread on the arms; does not a pain in the + left arm distinguish a disease of the pericardium, as in the angina + pectoris, or in the dropsy of the pericardium? and does not a pain or + weakness in both arms distinguish the dropsy of the thorax?</p> + + <p>8. Do not the dropsies of the thorax and pericardium frequently exist + together, and thus add to the uncertainty and fatality of the + disease?</p> + + <p>9. Might not the foxglove be serviceable in hydrocephalus internus, in + hydrocele, and in white swellings of the joints?</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_6">VI</a>. <i>Of cold Sweats.</i></p> + + <p>There have been histories given of chronical immoderate sweatings, + which bear some analogy to the diabetes. Dr. Willis mentions a lady then + living, whose sweats where for many years so profuse, that all her + bed-clothes were not only moistened, but deluged with them every night; + and that many ounces, and sometimes pints, of this sweat, were received + in vessels properly placed, as it trickled down her body. He adds, that + she had great thirst, had taken many medicines, and submitted to various + rules of life, and changes of climate, but still continued to have these + immoderate sweats. Pharmac. ration. de sudore anglico.</p> + + <p>Dr. Willis has also observed, that the sudor anglicanus which appeared + in England, in 1483, and continued till 1551, was in some respects + similar to the diabetes; and as Dr. Caius, who saw this disease, mentions + the viscidity, as well as the quantity of these sweats, and adds, that + the extremities were often cold, when the internal parts were burnt up + with heat and thirst, with great and speedy emaciation and debility: + there is great reason to believe, that the fluids were absorbed from the + cells of the body by the cellular and cystic branches of the lymphatics, + and poured on the skin by the retrograde motions of the cutaneous + ones.</p> + + <p>Sydenham has recorded, in the stationary fever of the year 1685, the + viscid sweats flowing from the head, which were probably from the same + source as those in the sweating plague above mentioned.</p> + + <p>It is very common in dropsies of the chest or lungs to have the + difficulty of breathing relieved by copious sweats, flowing from the head + and neck. Mr. P. about 50 years of age, had for many weeks been afflicted + with anasarca of his legs and thighs, attended with difficulty of + breathing; and had repeatedly been relieved by squill, other bitters, and + chalybeates.—One night the difficulty of breathing became so great, + that it was thought he must have expired; but so copious a sweat came out + of his head and neck, that in a few hours some pints, by estimation, were + wiped off from those parts, and his breath was for a time relieved. This + dyspnœa and these sweats recurred at intervals, and after some weeks + he ceased to exist. The skin of his head and neck felt cold to the hand, + and appeared pale at the time these sweats flowed so abundantly; which is + a proof, that they were produced by an inverted motion of the absorbents + of those parts: for sweats, which are the consequence of an increased + action of the sanguiferous system, are always attended with a warmth of + the skin, greater than is natural, and a more florid colour; as the + sweats from exercise, or those that succeed the cold fits of agues. Can + any one explain how these partial sweats should relieve the difficulty of + breathing in anasarca, but by supposing that the pulmonary branch of + absorbents drank up the fluid in the cavity of the thorax, or in the + cells of the lungs, and threw it on the skin, by the retrograde motions + of the cutaneous branch? for, if we could suppose, that the increased + action of the cutaneous glands or capillaries poured upon the skin this + fluid, previously absorbed from the lungs; why is not the whole surface + of the body covered with sweat? why is not the skin warm? Add to this, + that the sweats above mentioned were clammy or glutinous, which the + condensed perspirable matter is not; whence it would seem to have been a + different fluid from that of common perspiration.</p> + + <p>Dr. Dobson, of Liverpool, has given a very ingenious explanation of + the acid sweats, which he observed in a diabetic patient—he thinks + part of the chyle is secreted by the skin, and afterwards undergoes an + acetous fermentation.—Can the chyle get thither, but by an inverted + motion of the cutaneous lymphatics? in the same manner as it is carried + to the bladder, by the inverted motions of the urinary lymphatics. Medic. + Observat. and Enq. London, vol. v.</p> + + <p>Are not the cold sweats in some fainting fits, and in dying people, + owing to an inverted motion of the cutaneous lymphatics? for in these + there can be no increased arterial or glandular action.</p> + + <p>Is the difficulty of breathing, arising from anasarca of the lungs, + relieved by sweats from the head and neck; whilst that difficulty of + breathing, which arises from a dropsy of the thorax, or pericardium, is + never attended with these sweats of the head? and thence can these + diseases be distinguished from each other? Do the periodic returns of + nocturnal asthma rise from a temporary dropsy of the lungs, collected + during their more torpid state in sound deep, and then re-absorbed by the + vehement efforts of the disordered organs of respiration, and carried off + by the copious sweats about the head and neck?</p> + + <p>More extensive and accurate dissections of the lymphatic system are + wanting to enable us to unravel these knots of science.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_7">VII</a>. <i>Translations of Matter, of Chyle, of Milk, of Urine. Operation +of purging Drugs applied externally.</i></p> + + <p><a name="sect_XXIX_7_1">1</a>. The translations of matter from one + part of the body to another, can only receive an explanation from the + doctrine of the occasional retrograde motions of some branches of the + lymphatic system: for how can matter, absorbed and mixed with the whole + mass of blood, be so hastily collected again in any one part? and is it + not an immutable law, in animal bodies, that each gland can secrete no + other, but its own proper fluid? which is, in part, fabricated in the + very gland by an animal process, which it there undergoes: of these + purulent translations innumerable and very remarkable instances are + recorded.</p> + + <p><a name="sect_XXIX_7_2">2</a>. The chyle, which is seen among the + materials thrown up by violent vomiting, or in purging stools, can only + come thither by its having been poured into the bowels by the inverted + motions of the lacteals: for our aliment is not converted into chyle in + the stomach or intestines by a chemical process, but is made in the very + mouths of the lacteals; or in the mesenteric glands; in the same manner + as other secreted fluids are made by an animal process in their adapted + glands.</p> + + <p>Here a curious phænomenon in the exhibition of mercury is worth + explaining:—If a moderate dose of calomel, as six or ten grains, be + swallowed, and within one or two days a cathartic is given, a salivation + is prevented: but after three or four days, a salivation having come on, + repeated purges every day, for a week or two, are required to eliminate + the mercury from the constitution. For this acrid metallic preparation, + being absorbed by the mouth of the lacteals, continues, for a time + arrested by the mesenteric glands, (as the variolous or venereal poisons + swell the subaxillar or inguinal glands): which, during the operation of + a cathartic, is returned into the intestines by the inverted action of + the lacteals, and thus carried out of the system.</p> + + <p>Hence we understand the use of vomits or purges, to those who have + swallowed either contagious or poisonous materials, even though exhibited + a day or even two days after such accidents; namely, that by the + retrograde motions of the lacteals and lymphatics, the material still + arrested in the mesenteric, or other glands, may be eliminated from the + body.</p> + + <p><a name="sect_XXIX_7_3">3</a>. Many instances of milk and chyle found + in ulcers are given by Haller, El. Physiol. t. vii. p. 12, 23, which + admit of no other explanation than by supposing, that the chyle, imbibed + by one branch of the absorbent system, was carried to the ulcer, by the + inverted motions of another branch of the same system.</p> + + <p><a name="sect_XXIX_7_4">4</a>. Mrs. P. on the second day after + delivery, was seized with a violent purging, in which, though opiates, + mucilages, the bark, and testacea were profusely used, continued many + days, till at length she recovered. During the time of this purging, no + milk could be drawn from her breasts; but the stools appeared like the + curd of milk broken into small pieces. In this case, was not the milk + taken up from the follicles of the pectoral glands, and thrown on the + intestines, by a retrogression of the intestinal absorbents? for how can + we for a moment suspect that the mucous glands of the intestines could + separate pure milk from the blood? Doctor Smelly has observed, that loose + stools, mixed with milk, which is curdled in the intestines, frequently + relieves the turgescency of the breasts of those who studiously repel + their milk. Cases in Midwifery, 43, No. 2. 1.</p> + + <p><a name="sect_XXIX_7_5">5</a>. J.F. Meckel observed in a patient, + whose urine was in small quantity and high coloured, that a copious sweat + under the arm-pits, of a perfectly urinous smell, stained the linen; + which ceased again when the usual quantity of urine was discharged by the + urethra. Here we must believe from analogy, that the urine was first + secreted in the kidneys, then re-absorbed by the increased action of the + urinary lymphatics, and lastly carried to the axillae by the retrograde + motions of the lymphatic branches of those parts. As in the jaundice it + is necessary, that the bile should first be secreted by the liver, and + re-absorbed into the circulation, to produce the yellowness of the skin; + as was formerly demonstrated by the late Dr. Munro, (Edin. Medical + Essays) and if in this patient the urine had been re-absorbed into the + mass of blood, as the bile in the jaundice, why was it not detected in + other parts of the body, as well as in the arm-pits?</p> + + <p><a name="sect_XXIX_7_6">6</a>. Cathartic and vermifuge medicines + applied externally to the abdomen, seem to be taken up by the cutaneous + branch of lymphatics, and poured on the intestines by the retrograde + motions of the lacteals, without having passed the circulation.</p> + + <p>For when the drastic purges are taken by the mouth, they excite the + lacteals of the intestines into retrograde motions, as appears from the + chyle, which is found coagulated among the fæces, as was shewn above, + (sect. 2 and 4.) And as the cutaneous lymphatics are joined with the + lacteals of the intestines, by frequent anastomoses; it would be more + extraordinary, when a strong purging drug, absorbed by the skin, is + carried to the anastomosing branches of the lacteals unchanged, if it + should not excite them into retrograde action as efficaciously, as if it + was taken by the mouth, and mixed with the food of the stomach.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_8">VIII</a>. <i>Circumstances by which the Fluids, that are effused by the retrograde +Motions of the absorbent Vessels, are distinguished.</i></p> + + <p><a name="sect_XXIX_8_1">1</a>. We frequently observe an unusual + quantity of mucus or other fluids in some diseases, although the action + of the glands, by which those fluids are separated from the blood, is not + unusually increased; but when the power of absorption alone is + diminished. Thus the catarrhal humour from the nostrils of some, who ride + in frosty weather; and the tears, which run down the cheeks of those, who + have an obstruction of the puncta lacrymalia; and the ichor of those + phagedenic ulcers, which are not attended with inflammation, are all + instances of this circumstance.</p> + + <p>These fluids however are easily distinguished from others by their + abounding in ammoniacal or muriatic salts; whence they inflame the + circumjacent skin: thus in the catarrh the upper lip becomes red and + swelled from the acrimony of the mucus, and patients complain of the + saltness of its taste. The eyes and cheeks are red with the corrosive + tears, and the ichor of some herpetic eruptions erodes far and wide the + contiguous parts, and is pungently salt to the taste, as some patients + have informed me.</p> + + <p>Whilst, on the contrary, those fluids, which are effused by the + retrograde action of the lymphatics, are for the most part mild and + innocent; as water, chyle, and the natural mucus: or they take their + properties from the materials previously absorbed, as in the coloured or + vinous urine, or that scented with asparagus, described before.</p> + + <p><a name="sect_XXIX_8_2">2</a>. Whenever the secretion of any fluid is + increased, there is at the same time an increased heat in the part; for + the secreted fluid, as the bile, did not previously exist in the mass of + blood, but a new combination is produced in the gland. Now as solutions + are attended with cold, so combinations are attended with heat; and it is + probable the sum of the heat given out by all the secreted fluids of + animal bodies may be the cause of their general heat above that of the + atmosphere.</p> + + <p>Hence the fluids derived from increased secretions are readily + distinguished from those originating from the retrograde motions of the + lymphatics: thus an increase of heat either in the diseased parts, or + diffused over the whole body, is perceptible, when copious bilious stools + are consequent to an inflamed liver; or a copious mucous salivation from + the inflammatory angina.</p> + + <p><a name="sect_XXIX_8_3">3</a>. When any secreted fluid is produced in + an unusual quantity, and at the same time the power of absorption is + increased in equal proportion, not only the heat of the gland becomes + more intense, but the secreted fluid becomes thicker and milder, its + thinner and saline parts being re-absorbed: and these are distinguishable + both by their greater consistence, and by their heat, from the fluids, + which are effused by the retrograde motions of the lymphatics; as is + observable towards the termination of gonorrhœa, catarrh, chincough, + and in those ulcers, which are said to abound with laudable pus.</p> + + <p><a name="sect_XXIX_8_4">4</a>. When chyle is observed in stools, or + among the materials ejected by vomit, we may be confident it must have + been brought thither by the retrograde motions of the lacteals; for chyle + does not previously exist amid the contents of the intestines, but is + made in the very mouths of the lacteals, as was before explained.</p> + + <p><a name="sect_XXIX_8_5">5</a>. 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 these have + been collected from the mass of blood by a morbid secretion, as it + contradicts all analogy.</p> + + <div class="poem"> + <div class="stanza"> + <p class="i16">—— Aurea duræ</p> + <p>Mala ferant quercus? Narcisco floreat alnus?</p> + <p>Pinguia corticibus sudent electra myricæ?—V<font class="sc">IRGIL</font>.</p> + </div> + </div> +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_9">IX</a>. <i>Retrograde Motions of Vegetable juices.</i></p> + + <p>There are besides some motions of the sap in vegetables, which bear + analogy to our present subject; and as the vegetable tribes are by many + philosophers held to be inferior animals, it may be a matter of curiosity + at least to observe, that their absorbent vessels seem evidently, at + times, to be capable of a retrograde motion. Mr. Perault cut off a forked + branch of a tree, with the leaves on; and inverting one of the forks into + a vessel of water, observed, that the leaves on the other branch + continued green much longer than those of a similar branch, cut off from + the same tree; which shews, that the water from the vessel was carried up + one part of the forked branch, by the retrograde motion of its vessels, + and supplied nutriment some time to the other part of the branch, which + was out of the water. And the celebrated Dr. Hales found, by numerous + very accurate experiments, that the sap of trees rose upwards during the + warmer hours of the day, and in part descended again during the cooler + ones. Vegetable Statics.</p> + + <p>It is well known that the branches of willows, and of many other + trees, will either take root in the earth or engraft on other trees, so + as to have their natural direction inverted, and yet flourish with + vigour.</p> + + <p>Dr. Hope has also made this pleasing experiment, after the manner of + Hales—he has placed a forked branch, cut from one tree, erect + between two others; then cutting off a part of the bark from one fork + applied it to a similar branch of one of the trees in its vicinity; and + the same of the other fork; so that a tree is seen to grow suspended in + the air, between two other trees; which supply their softer friend with + due nourishment.</p> + + <div class="poem"> + <div class="stanza"> + <p>Miranturque novas frondes, et non sua poma.</p> + </div> + </div> + <p>All these experiments clearly evince, that the juices of vegetables + can occasionally pass either upwards or downwards in their absorbent + system of vessels.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_10">X</a>. <i>Objections answered.</i></p> + + <p>The following experiment, at first view, would seem to invalidate this + opinion of the retrograde motions of the lymphatic vessels, in some + diseases.</p> + + <p>About a gallon of milk having been giving to an hungry swine, he was + suffered to live about an hour, and was then killed by a stroke or two on + his head with an axe.—On opening his belly the lacteals were well + seen filled with chyle; on irritating many of the branches of them with a + knife, they did not appear to empty themselves hastily; but they did + however carry forwards their contents in a little time.</p> + + <p>I then passed a ligature round several branches of lacteals, and + irritated them much with a knife beneath the ligature, but could not make + them regurgitate their contained fluid into the bowels.</p> + + <p>I am not indeed certain, that the nerve was not at the same time + included in the ligature, and thus the lymphatic rendered unirritable or + lifeless; but this however is certain, that it is not any quantity of any + stimulus, which induces the vessels of animal bodies to revert their + motions; but a certain quantity of a certain stimulus, as appears from + wounds in the stomach, which do not produce vomiting; and wounds of the + intestines, which do not produce the cholera morbus.</p> + + <p>At Nottingham, a few years ago, two shoemakers quarrelled, and one of + them with a knife, which they use in their occupation, stabbed his + companion about the region of the stomach. On opening the abdomen of the + wounded man after his death the food and medicines he had taken were in + part found in the cavity of the belly, on the outside of the bowels; and + there was a wound about half an inch long at the bottom of the stomach; + which I suppose was distended 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, which was about ten days, he had no + efforts to vomit, nor ever even complained of being sick at the stomach! + Other cases similar to this are mentioned in the philosophical + transactions.</p> + + <p>Thus, if you vellicate the throat with a feather, nausea is produced; + if you wound it with a penknife, pain is induced, but not sickness. So if + the soles of the feet of children or their armpits are tickled, + convulsive laughter is excited, which ceases the moment the hand is + applied, so as to rub them more forcibly.</p> + + <p>The experiment therefore above related upon the lacteals of a dead + pig, which were included in a strict ligature, proves nothing; as it is + not the quantity, but the kind of stimulus, which excites the lymphatic + vessels into retrograde motion.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXIX_11">XI</a>. <i>The Causes which induce the retrograde Motions of animal Vessels; +and the Medicines by which the natural Motions are restored.</i></p> + + <p><a name="sect_XXIX_11_1">1</a>. Such is the construction of animal + bodies, that all their parts, which are subjected to less stimuli than + nature designed, perform their functions with less accuracy: thus, when + too watery or too acescent food is taken into the stomach, indigestion, + and flatulency, and heartburn succeed.</p> + + <p><a name="sect_XXIX_11_2">2</a>. Another law of irritation, connate + with our existence, is, that all those parts of the body, which have + previously been exposed to too great a quantity of such stimuli, as + strongly affect them, become for some time afterwards disobedient to the + natural quantity of their adapted stimuli.—Thus the eye is + incapable of seeing objects in an obscure room, though the iris is quite + dilated, after having been exposed to the meridian sun.</p> + + <p><a name="sect_XXIX_11_3">3</a>. There is a third law of irritation, + that all the parts of our bodies, which have been lately subjected to + less stimulus, than they have been accustomed to, when they are exposed + to their usual quantity of stimulus, are excited into more energetic + motions: thus when we come from a dusky cavern into the glare of + daylight, our eyes are dazzled; and after emerging from the cold bath, + the skin becomes warm and red.</p> + + <p><a name="sect_XXIX_11_4">4</a>. There is a fourth law of irritation, + that all the parts of our bodies, which are subjected to still stronger + stimuli for a length of time, become torpid, and refuse to obey even + these stronger stimuli; and thence do their offices very + imperfectly.—Thus, if any one looks earnestly for some minutes on + an area, an inch diameter, of red silk, placed on a sheet of white paper, + the image of the silk will gradually become pale, and at length totally + vanish.</p> + + <p><a name="sect_XXIX_11_5">5</a>. Nor is it the nerves of sense alone, + as the optic and auditory nerves, that thus become torpid, when the + stimulus is withdrawn or their irritability decreased; but the motive + muscles, when they are deprived of their natural stimuli, or of their + irritability, become torpid and paralytic; as is seen in the tremulous + hand of the drunkard in a morning; and in the awkward step of age.</p> + + <p>The hollow muscles also, of which the various vessels of the body are + constructed, when they are deprived of their natural stimuli, or of their + due degree of irritability, not only become tremulous, as the arterial + pulsations of dying people; but also frequently invert their motions, as + in vomiting, in hysteric suffocations, and diabetes above described.</p> + + <p>I must beg your patient attention, for a few moments whilst I + endeavour to explain, how the retrograde actions of our hollow muscles + are the consequence of their debility; as the tremulous actions of the + solid muscles are the consequence of their debility. When, through + fatigue, a muscle can act no longer; the antagonist muscles, either by + their inanimate elasticity, or by their animal action, draw the limb into + a contrary direction: in the solid muscles, as those of locomotion, their + actions are associated in tribes, which have been accustomed to + synchronous action only; hence when they are fatigued, only a single + contrary effort takes place; which is either tremulous, when the fatigued + muscles are again immediately brought into action; or it is a + pandiculation, or stretching, where they are not immediately again + brought into action.</p> + + <p>Now the motions of the hollow muscles, as they in general propel a + fluid along their cavities, are associated in trains, which have been + accustomed to successive actions: hence when one ring of such a muscle is + fatigued from its too great debility, and is brought into retrograde + action, the next ring from its association falls successively into + retrograde action; and so on throughout the whole canal. See Sect. <a + href="#sect_XXV_6">XXV. 6</a>.</p> + + <p><a name="sect_XXIX_11_6">6</a>. But as the retrograde motions of the + stomach, œsophagus, and fauces in vomiting are, as it were, apparent + to the eye; we shall consider this operation more minutely, that the + similar operations in the more recondite parts of our system may be + easier understood.</p> + + <p>From certain nauseous ideas of the mind, from an ungrateful taste in + the mouth, or from fœtid smells, vomiting is sometimes instantly + excited; or even from a stroke on the head, or from the vibratory motions + of a ship; all which originate from association, or sympathy. See Sect. + <a href="#sect_XX">XX</a>. on Vertigo.</p> + + <p>But when the stomach is subjected to a less stimulus than is natural, + according to the first law of irritation mentioned above, its motions + become disturbed, as in hunger; first pain is produced, then sickness, + and at length vain efforts to vomit, as many authors inform us.</p> + + <p>But when a great quantity of wine, or of opium, is swallowed, the + retrograde motions of the stomach do not occur till after several + minutes, or even hours; for when the power of so strong a stimulus + ceases, according to the second law of irritation, mentioned above, the + peristaltic motions become tremulous, and at length retrograde; as is + well known to the drunkard, who on the next morning has sickness and + vomitings.</p> + + <p>When a still greater quantity of wine, or of opium, or when nauseous + vegetables, or strong bitters, or metallic salts, are taken into the + stomach, they quickly induce vomiting; though all these in less doses + excite the stomach into more energetic action, and strengthen the + digestion; as the flowers of chamomile, and the vitriol of zinc: for, + according to the fourth law of irritation, the stomach will not long be + obedient to a stimulus so much greater than is natural; but its action + becomes first tremulous and then retrograde.</p> + + <p><a name="sect_XXIX_11_7">7</a>. When the motions of any vessels become + retrograde, less heat of the body is produced; for in paroxysms of + vomiting, of hysteric affections, of diabetes, of asthma, the extremities + of the body are cold: hence we may conclude, that these symptoms arise + from the debility of the parts in action; for an increase of muscular + action is always attended with increase of heat.</p> + + <p><a name="sect_XXIX_11_8">8</a>. But as animal debility is owing to + defect of stimulus, or to defect of irritability, as shewn above, the + method of cure is easily deduced: when the vascular muscles are not + excited into their due action by the natural stimuli, we should exhibit + those medicines, which possess a still greater degree of stimulus; + amongst these are the fœtids, the volatiles, aromatics, bitters, + metallic salts, opiates, wine, which indeed should be given in small + doses, and frequently repeated. To these should be added constant, but + moderate exercise, cheerfulness of mind, and change of country to a + warmer climate; and perhaps occasionally the external stimulus of + blisters.</p> + + <p>It is also frequently useful to diminish the quantity of natural + stimulus for a short time, by which afterwards the irritability of the + system becomes increased; according to the third law of irritation + above-mentioned, hence the use of baths somewhat colder than animal heat, + and of equitation in the open air.</p> + + <p><i>The catalogue of diseases owing to the retrograde motions of + lymphatics is here omitted, as it will appear in the second volume of + this work. The following is the conclusion to this thesis of</i> Mr. + C<font class="sc">HARLES</font> D<font class="sc">ARWIN</font>.</p> + + <p>Thus have I endeavoured in a concise manner to explain the numerous + diseases, which deduce their origin from the inverted motions of the + hollow muscles of our bodies: and it is probable, that Saint Vitus's + dance, and the stammering of speech, originate from a similar, inverted + order of the associated motions of some of the solid muscles; which, as + it is foreign to my present purpose, I shall not here discuss.</p> + + <p>I beg, illustrious professors, and ingenious fellow-students, that you + will recollect how difficult a talk I have attempted, to evince the + retrograde motions of the lymphatic vessels, when the vessels themselves + for so many ages escaped the eyes and glasses of philosophers: and if you + are not yet convinced of the truth of this theory, hold, I entreat you, + your minds in suspense, till A<font class="sc">NATOMY</font> draws her + sword with happier omens, cuts asunder the knots, which entangle P<font + class="sc">HYSIOLOGY</font>; and, like an augur inspecting the immolated + victim, announces to mankind the wisdom of HEAVEN.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXX">XXX</a>.</h3> + +<p class="center" style="margin-top: 2em;">PARALYSIS OF THE LIVER AND KIDNEYS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXX_1">I</a>. <a + href="#sect_XXX_1_1">1</a>.<i>Bile-ducts less irritable after having been + stimulated much.</i> <a href="#sect_XXX_1_2">2</a>. <i>Jaundice from + paralysis of the bile-ducts cured by electric shocks.</i> <a + href="#sect_XXX_1_3">3</a>. <i>From bile-stones. Experiments on + bile-stones. Oil vomit.</i> <a href="#sect_XXX_1_4">4</a>. <i>Palsy of + the liver, two cases.</i> <a href="#sect_XXX_1_5">5</a>. <i>Schirrosity + of the liver.</i> <a href="#sect_XXX_1_6">6</a>. <i>Large livers of + geese.</i> <a href="#sect_XXX_2">II</a>. <i>Paralysis of the kidneys.</i> + <a href="#sect_XXX_3">III</a>. <i>Story of Prometheus.</i></p> + +</blockquote> + + <p><a name="sect_XXX_1">I</a>. <a name="sect_XXX_1_1">1</a>. From the + ingurgitation of spirituous liquors into the stomach and duodenum, the + termination of the common bile-duct in that bowel becomes stimulated into + unnatural action, and a greater quantity of bile is produced from all the + secretory vessels of the liver, by the association of their motions with + those of their excretory ducts; as has been explained in Section <a + href="#sect_XXIV">XXIV</a>. and <a href="#sect_XXV">XXV</a>. but as all + parts of the body, that have been affected with stronger stimuli for any + length of time, become less susceptible of motion, from their natural + weaker stimuli, it follows, that the motions of the secretory vessels, + and in consequence the secretion of bile, is less than is natural during + the intervals of sobriety. <a name="sect_XXX_1_2">2</a>. If this + ingurgitation of spirituous liquors has been daily continued in + considerable quantity, and is then suddenly intermitted, a languor or + paralysis of the common bile-duct is induced; the bile is prevented from + being poured into the intestines; and as the bilious absorbents are + stimulated into stronger action by its accumulation, and by the acrimony + or viscidity, which it acquires by delay, it is absorbed, and carried to + the receptacle of the chyle; or otherwise the secretory vessels of the + liver, by the above-mentioned stimulus, invert their motions, and + regurgitate their contents into the blood, as sometimes happens to the + tears in the lachrymal sack, see Sect. <a href="#sect_XXIV_2_7">XXIV. 2. + 7</a>. and one kind of jaundice is brought on.</p> + + <p>There is reason to believe, that the bile is most frequently returned + into the circulation by the inverted motions of these hepatic glands, for + the bile does not seem liable to be absorbed by the lymphatics, for it + soaks through the gall-ducts, and is frequently found in the cellular + membrane. This kind of jaundice is not generally attended with pain, + neither at the extremity of the bile-duct, where it enters the duodenum, + nor on the region of the gall-bladder.</p> + + <p>Mr. S. a gentleman between 40 and 50 years of age, had had the + jaundice about six weeks, without pain, sickness, or fever; and had taken + emetics, cathartics, mercurials, bitters, chalybeates, essential oil, and + ether, without apparent advantage. On a supposition that the obstruction + of the bile might be owing to the paralysis, or torpid action of the + common bile-duct, and the stimulants taken into the stomach seeming to + have no effect, I directed half a score smart electric shocks from a + coated bottle, which held about a quart, to be passed through the liver, + and along the course of the common gall-duct, as near as could be + guessed, and on that very day the stools became yellow; he continued the + electric shocks a few days more, and his skin gradually became clear.</p> + + <p><a name="sect_XXX_1_3">3</a>. The bilious vomiting and purging, that + affects some people by intervals of a few weeks, is a less degree of this + disease; the bile-duct is less irritable than natural, and hence the bile + becomes accumulated in the gall-bladder, and hepatic ducts, till by its + quantity, acrimony or viscidity, a greater degree of irritation is + produced, and it is suddenly evacuated, or lastly from the absorption of + the more liquid parts of the bile, the remainder becomes inspissated, and + chrystallizes into masses too large to pass, and forms another kind of + jaundice, where the bile-duct is not quite paralytic, or has regained its + irritability.</p> + + <p>This disease is attended with much pain, which at first is felt at the + pit of the stomach, exactly in the centre of the body, where the + bile-duct enters the duodenum; afterwards, when the size of the + bile-stones increase, it is also felt on the right side, where the + gall-bladder is situated. The former pain at the pit of the stomach + recurs by intervals, as the bile-stone is pushed against the neck of the + duct; like the paroxysms of the stone in the urinary bladder, the other + is a more dull and constant pain.</p> + + <p>Where these bile-stones are too large to pass, and the bile-ducts + possess their sensibility, this becomes a very painful and hopeless + disease. I made the following experiments with a view to their chemical + solution.</p> + + <p>Some fragments of the same bile-stone were put into the weak spirit of + marine salt, which is sold in the shops, and into solution of mild + alcali; and into a solution of caustic alcali; and into oil of + turpentine; without their being dissolved. All these mixtures were after + some time put into a heat of boiling water, and then the oil of + turpentine dissolved its fragments of bile-stone, but no alteration was + produced upon those in the other liquids except some change of their + colour.</p> + + <p>Some fragments of the same bile-stone were put into vitriolic æther, + and were quickly dissolved without additional heat. Might not æther mixed + with yolk of egg or with honey be given advantageously in bilious + concretions?</p> + + <p>I have in two instances seen from 30 to 50 bile-stones come away by + stool, about the size of large peas, after having given six grains of + calomel in the evening, and four ounces of oil of almonds or olives on + the succeeding morning. I have also 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 first did not operate, with frequent good effect.</p> + + <p><a name="sect_XXX_1_4">4</a>. Another disease of the liver, which I + have several times observed, consists in the inability or paralysis of + the secretory vessels. This disease has generally the same cause as the + preceding one, the too frequent potation of spirituous liquors, or the + too sudden omission of them, after the habit is confined; and is greater + or less in proportion, as the whole or a part of the liver is affected, + and as the inability or paralysis is more or less complete.</p> + + <p>This palsy of the liver is known from these symptoms, the patients + have generally passed the meridian of life, have drank fermented liquors + daily, but perhaps not been opprobrious drunkards; they lose their + appetite, then their flesh and strength diminish in consequence, there + appears no bile in their stools, nor in their urine, nor is any hardness + or swelling perceptible on the region of the liver. But what is peculiar + to this disease, and distinguishes it from all others at the first glance + of the eye, is the bombycinous colour of the skin, which, like that of + full-grown silkworms, has a degree of transparency with a yellow tint not + greater than is natural to the serum of the blood.</p> + + <p>Mr. C. and Mr. B. both very strong men, between 50 and 60 years of + age, who had drank ale at their meals instead of small beer, but were not + reputed hard-drinkers, suddenly became weak, lost their appetite, flesh, + and strength, with all the symptoms above enumerated, and died in about + two months from the beginning of their malady. Mr. C. became anasarcous a + few days before his death, and Mr. B. had frequent and great hæmorrhages + from an issue, and some parts of his mouth, a few days before his death. + In both these cases calomel, bitters and chalybeates were repeatedly used + without effect.</p> + + <p>One of the patients described above, Mr. C, was by trade a plumber; + both of them could digest no food, and died apparently for want of blood. + Might not the transfusion of blood be used in these cases with + advantage?</p> + + <p><a name="sect_XXX_1_5">5</a>. When the paralysis of the hepatic glands + is less complete, or less universal, a schirrosity of some part of the + liver is induced; for the secretory vessels retaining some of their + living power take up a fluid from the circulation, without being + sufficiently irritable to carry it forwards to their excretory ducts; + hence the body, or receptacle of each gland, becomes inflated, and this + distension increases, till by its very great stimulus inflammation is + produced, or till those parts of the viscus become totally paralytic. + This disease is distinguishable from the foregoing by the palpable + hardness or largeness of the liver; and as the hepatic glands are not + totally paralytic, or the whole liver not affected, some bile continues + to be made. The inflammations of this viscus, consequent to the + schirrosity of it, belong to the diseases of the sensitive motions, and + will be treated of hereafter.</p> + + <p><a name="sect_XXX_1_6">6</a>. The ancients are said to have possessed + an art of increasing the livers of geese to a size greater than the + remainder of the goose. Martial. l. 13. epig. 58.—This is said to + have been done by fat and figs. Horace, l. 2. sat. 8.—Juvenal sets + these large livers before an epicure as a great rarity. Sat. 5. l. 114; + and Persius, sat. 6. l. 71. Pliny says these large goose-livers were + soaked in mulled milk, that is, I suppose, milk mixed with honey and + wine; and adds, "that it is uncertain whether Scipio Metellus, of + consular dignity, or M. Sestius, a Roman knight, was the great discoverer + of this excellent dish." A modern traveller, I believe Mr. Brydone, + asserts that the art of enlarging the livers of geese still exists in + Sicily; and it is to be lamented that he did not import it into his + native country, as some method of affecting the human liver might perhaps + have been collected from it; besides the honour he might have acquired in + improving our giblet pies.</p> + + <p>Our wiser caupones, I am told, know how to fatten their fowls, as well + as their geese, for the London markets, by mixing gin instead of figs and + fat with their food; by which they are said to become sleepy, and to + fatten apace, and probably acquire enlarged livers; as the swine are + asserted to do, which are fed on the sediments of barrels in the + distilleries; and which so frequently obtains in those, who ingurgitate + much ale, or wine, or drams.</p> + + <p><a name="sect_XXX_2">II</a>. The irritative diseases of the kidneys, + pancreas, spleen, and other glands, are analogous to those of the liver + above described, differing only in the consequences attending their + inability to action. For instance, when the secretory vessels of the + kidneys become disobedient to the stimulus of the passing current of + blood, no urine is separated or produced by them; their excretory mouths + become filled with concreted mucus, or calculus matter, and in eight or + ten days stupor and death supervenes in consequence of the retention of + the feculent part of the blood.</p> + + <p>This disease in a slighter degree, or when only a part of the kidney + is affected, is succeeded by partial inflammation of the kidney in + consequence of previous torpor. In that case greater actions of the + secretory vessels occur, and the nucleus of gravel is formed by the + inflamed mucous membranes of the tubuli uriniferi, as farther explained + in its place.</p> + + <p>This torpor, or paralysis of the secretory vessels of the kidneys, + like that of the liver, owes its origin to their being previously + habituated to too great stimulus; which in this country is generally + owing to the alcohol contained in ale or wine; and hence must be + registered amongst the diseases owing to inebriety; though it may be + caused by whatever occasionally inflames the kidney; as too violent + riding on horseback, or the cold from a damp bed, or by sleeping on the + cold ground; or perhaps by drinking in general too little aqueous + fluids.</p> + + <p><a name="sect_XXX_3">III</a>. I shall conclude this section on the + diseases of the liver induced by spirituous liquors, with the well known + story of Prometheus, which seems indeed to have been invented by + physicians in those ancient times, when all things were clothed in + hieroglyphic, or in fable. Prometheus was painted as stealing fire from + heaven, which might well represent the inflammable spirit produced by + fermentation; which may be said to animate or enliven the man of clay: + whence the conquests of Bacchus, as well as the temporary mirth and noise + of his devotees. But the after punishment of those, who steal this + accursed fire, is a vulture gnawing the liver; and well allegorises the + poor inebriate lingering for years under painful hepatic diseases. When + the expediency of laying a further tax on the distillation of spirituous + liquors from grain was canvassed before the House of Commons some years + ago, it was said of the distillers, with great truth, "<i>They take the + bread from the people, and convert it into poison!</i>" Yet is this + manufactory of disease permitted to continue, as appears by its paying + into the treasury above 900,000<i>l.</i> near a million of money + annually. And thus, under the names of rum, brandy, gin, whisky, + usquebaugh, wine, cyder, beer, and porter, alcohol is become the bane of + the Christian world, as opium of the Mahometan.</p> + + <div class="poem"> + <div class="stanza"> + <p class="i8">Evoe! parce, liber?</p> + <p>Parce, gravi metuende thirso!—Hor.</p> + </div> + </div> + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXXI">XXXI</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF TEMPERAMENTS.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXXI_1">I</a>. <i>The temperament of decreased + irritability known by weak pulse, large pupils of the eyes, cold + extremities. Are generally supposed to be too irritable. Bear pain better + than labour. Natives of North-America contrasted with those upon the + coast of Africa. Narrow and broad shouldered people. Irritable + constitutions bear labour better than pain.</i> <a + href="#sect_XXXI_2">II</a>. <i>Temperament of increased sensibility. + Liable to intoxication, to inflammation, hæmoptoe, gutta serena, + enthusiasm, delirium, reverie. These constitutions are indolent to + voluntary exertions, and dull to irritations. The natives of + South-America, and brute animals of this temperament.</i> <a + href="#sect_XXXI_3">III</a>. <i>Of increased voluntarity; these are + subject to locked jaw, convulsions, epilepsy, mania. Are very active, + bear cold, hunger, fatigue. Are suited to great exertions. This + temperament distinguishes mankind from other animals.</i> <a + href="#sect_XXXI_4">IV</a>. <i>Of increased association. These have great + memories, are liable to quartan agues, and stronger sympathies of parts + with each other.</i> <a href="#sect_XXXI_5">V</a>. <i>Change of + temperaments into one another.</i></p> + +</blockquote> + + <p>Antient writers have spoken much of temperaments, but without + sufficient precision. By temperament of the system should be meant a + permanent predisposition to certain classes of diseases: without this + definition a temporary predisposition to every distinct malady might be + termed a temperament. There are four kinds of constitution, which + permanently deviate from good health, and are perhaps sufficiently marked + to be distinguished from each other, and constitute the temperaments or + predispositions to the irritative, sensitive, voluntary, and associate + classes of diseases.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXXI_1">I</a>. <i>The Temperament of decreased Irritability.</i></p> + + <p>The diseases, which are caused by irritation, most frequently + originate from the defect of it; for those, which are immediately owing + to the excess of it, as the hot fits of fever, are generally occasioned + by an accumulation of sensorial power in consequence of a previous defect + of irritation, as in the preceding cold fits of fever. Whereas the + diseases, which are caused by sensation and volition, most frequently + originate from the excess of those sensorial powers, as will be explained + below.</p> + + <p>The temperament of decreased irritability appears from the following + circumstances, which shew that the muscular fibres or organs of sense are + liable to become torpid or quiescent from less defect of stimulation than + is productive of torpor or quiescence in other constitutions.</p> + + <p><a name="sect_XXXI_1_1">1</a>. The first is the weak pulse, which in + some constitutions is at the same time quick. 2. The next most marked + criterion of this temperament is the largeness of the aperture of the + iris, or pupil of the eye, which has been reckoned by some a beautiful + feature in the female countenance, as an indication of delicacy, but to + an experienced observer it is an indication of debility, and is therefore + a defect, not an excellence. The third most marked circumstance in this + constitution is, that the extremities, as the hands and feet, or nose and + ears, are liable to become cold and pale in situations in respect to + warmth, where those of greater strength are not affected. Those of this + temperament are subject to hysteric affections, nervous fevers, + hydrocephalus, scrophula, and consumption, and to all other diseases of + debility.</p> + + <p>Those, who possess this kind of constitution, are popularly supposed + to be more irritable than is natural, but are in reality less so.</p> + + <p>This mistake has arisen from their generally having a greater + quickness of pulse, as explained in Sect. <a href="#sect_XII_1_4">XII. 1. + 4</a>. <a href="#sect_XII_3_3">XII. 3. 3</a>.; but this frequency of + pulse is not necessary to the temperament, like the debility of it.</p> + + <p>Persons of this temperament are frequently found amongst the softer + sex, and amongst narrow-shouldered men; who are said to bear labour + worse, and pain better than others. This last circumstance is supposed to + have prevented the natives of North America from having been made slaves + by the Europeans. They are a narrow-shouldered race of people, and will + rather expire under the lash, than be made to labour. Some nations of + Asia have small hands, as may be seen by the handles of their scymetars; + which with their narrow shoulders shew, that they have not been + accustomed to so great labour with their hands and arms, as the European + nations in agriculture, and those on the coasts of Africa in swimming and + rowing. Dr. Maningham, a popular accoucheur in the beginning of this + century, observes in his aphorisms, that broad-shouldered men procreate + broad-shouldered children. Now as labour strengthens the muscles + employed, and increases their bulk, it would seem that a few generations + of labour or of indolence may in this respect change the form and + temperament of the body.</p> + + <p>On the contrary, those who are happily possessed of a great degree of + irritability, bear labour better than pain; and are strong, active, and + ingenious. But there is not properly a temperament of increased + irritability tending to disease, because an increased quantity of + irritative motions generally induces an increase of pleasure or pain, as + in intoxication, or inflammation; and then the new motions are the + immediate consequences of increased sensation, not of increased + irritation; which have hence been so perpetually confounded with each + other.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXXI_2">II</a>. <i>Temperament of Sensibility.</i></p> + + <p>There is not properly a temperament, or predisposition to disease, + from decreased sensibility, since irritability and not sensibility is + immediately necessary to bodily health. Hence it is the excess of + sensation alone, as it is the defect of irritation, that most frequently + produces disease. This temperament of increased sensibility is known from + the increased activity of all those motions of the organs of sense and + muscles, which are exerted in consequence of pleasure or pain, as in the + beginning of drunkenness, and in inflammatory fever. Hence those of this + constitution are liable to inflammatory diseases, as hepatitis; and to + that kind of consumption which is hereditary, and commences with slight + repeated hæmoptoe. They have high-coloured lips, frequently dark hair and + dark eyes with large pupils, and are in that case subject to gutta + serena. They are liable to enthusiasm, delirium, and reverie. In this + last circumstance they are liable to start at the clapping of a door; + because the more intent any one is on the passing current of his ideas, + the greater surprise he experiences on their being dissevered by some + external violence, as explained in Sect. <a href="#sect_XIX">XIX</a>. on + reverie.</p> + + <p>As in these constitutions more than the natural quantities of + sensitive motions are produced by the increased quantity of sensation + existing in the habit, it follows, that the irritative motions will be + performed in some degree with less energy, owing to the great expenditure + of sensorial power on the sensitive ones. Hence those of this temperament + do not attend to slight stimulations, as explained in Sect. <a + href="#sect_XIX">XIX</a>. But when a stimulus is so great as to excite + sensation, it produces greater sensitive actions of the system than in + others; such as delirium or inflammation. Hence they are liable to be + absent in company; sit or lie long in one posture; and in winter have the + skin of their legs burnt into various colours by the fire. Hence also + they are fearful of pain; covet music and sleep; and delight in poetry + and romance.</p> + + <p>As the motions in consequence of sensation are more than natural, it + also happens from the greater expenditure of sensorial power on them, + that the voluntary motions are less easily exerted. Hence the subjects of + this temperament are indolent in respect to all voluntary exertions, + whether of mind or body.</p> + + <p>A race of people of this description seems to have been found by the + Spaniards in the islands of America, where they first landed, ten of whom + are said not to have consumed more food than one Spaniard, nor to have + been capable of more than one tenth of the exertion of a Spaniard. + Robertson's History.—In a state similar to this the greatest part + of the animal world pass their lives, between sleep or inactive reverie, + except when they are excited by the call of hunger.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXXI_3">III</a>. <i>The Temperament of increased Voluntarity.</i></p> + + <p>Those of this constitution differ from both the last mentioned in + this, that the pain, which gradually subsides in the first, and is + productive of inflammation or delirium in the second, is in this + succeeded by the exertion of the muscles or ideas, which are most + frequently connected with volition; and they are thence subject to locked + jaw, convulsions, epilepsy, and mania, as explained in Sect. <a + href="#sect_XXXIV">XXXIV</a>. Those of this temperament attend to the + slightest irritations or sensations, and immediately exert themselves to + obtain or avoid the objects of them; they can at the same time bear cold + and hunger better than others, of which Charles the Twelfth of Sweden was + an instance. They are suited and generally prompted to all great + exertions of genius or labour, as their desires are more extensive and + more vehement, and their powers of attention and of labour greater. It is + this facility of voluntary exertion, which distinguishes men from brutes, + and which has made them lords of the creation.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XXXI_4">IV</a>. <i>The Temperament of increased Association.</i></p> + + <p>This constitution consists in the too great facility, with which the + fibrous motions acquire habits of association, and by which these + associations become proportionably stronger than in those of the other + temperaments. Those of this temperament are slow in voluntary exertions, + or in those dependent on sensation, or on irritation. Hence great + memories have been said to be attended with less sense and less + imagination from Aristotle down to the present time; for by the word + memory these writers only understood the unmeaning repetition of words or + numbers in the order they were received, without any voluntary efforts of + the mind.</p> + + <p>In this temperament those associations of motions, which are commonly + termed sympathies, act with greater certainty and energy, as those + between disturbed vision and the inversion of the motion of the stomach, + as in sea-sickness; and the pains in the shoulder from hepatic + inflammation. Add to this, that the catenated circles of actions are of + greater extent than in the other constitutions. Thus if a strong vomit or + cathartic be exhibited in this temperament, a smaller quantity will + produce as great an effect, if it be given some weeks afterwards; whereas + in other temperaments this is only to be expected, if it be exhibited in + a few days after the first dose. Hence quartan agues are formed in those + of this temperament, as explained in Section <a + href="#sect_XXXII">XXXII</a>. on diseases from irritation, and other + intermittents are liable to recur from slight causes many weeks after + they have been cured by the bark.</p> + + <p><a name="sect_XXXI_5">V</a>. The first of these temperaments differs + from the standard of health from defect, and the others from excess of + sensorial power; but it sometimes happens that the same individual, from + the changes introduced into his habit by the different seasons of the + year, modes or periods of life, or by accidental diseases, passes from + one of these temperaments to another. Thus a long use of too much + fermented liquor produces the temperament of increased sensibility; great + indolence and solitude that of decreased irritability; and want of the + necessaries of life that of increased voluntarity.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXXII">XXXII</a>.</h3> + +<p class="center" style="margin-top: 2em;">DISEASES OF IRRITATION.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXXII_1">I</a>. <i>Irritative fevers with strong pulse. + With weak pulse. Symptoms of fever, Their source.</i> <a + href="#sect_XXXII_2">II</a>. <a href="#sect_XXXII_2_1">1</a>. <i>Quick + pulse is owing to decreased irritability</i>. <a + href="#sect_XXXII_2_2">2</a>. <i>Not in sleep or in apoplexy.</i> <a + href="#sect_XXXII_2_3">3</a>. <i>From inanition. Owing to deficiency of + sensorial power.</i> <a href="#sect_XXXII_3">III</a>. <a + href="#sect_XXXII_3_1">1</a>. <i>Causes of fever. From defect of heat. + Heat from secretions. Pain of cold in the loins and forehead.</i> <a + href="#sect_XXXII_3_2">2</a>. <i>Great expense of sensorial power in the + vital motions. Immersion in cold water. Succeeding glow of heat. + Difficult respiration in cold bathing explained. Why the cold bath + invigorates. Bracing and relaxation are mechanical terms.</i> <a + href="#sect_XXXII_3_3">3</a>. <i>Uses of cold bathing. Uses of cold air + in fevers.</i> <a href="#sect_XXXII_3_4">4</a>. <i>Ague fits from cold + air. Whence their periodical returns.</i> <a href="#sect_XXXII_4">IV</a>. + <i>Defect of distention a cause of fever. Deficiency of blood. + Transfusion of blood.</i> <a href="#sect_XXXII_5">V</a>. <a + href="#sect_XXXII_5_1">1</a>. <i>Defect of momentum of the blood from + mechanic stimuli. <a href="#sect_XXXII_5_2">2</a>. Air injected into the + blood-vessels.</i> <a href="#sect_XXXII_5_3">3</a>. <i>Exercise increases + the momentum of the blood.</i> <a href="#sect_XXXII_5_4">4</a>. + <i>Sometimes bleeding increases the momentum of it.</i> <a + href="#sect_XXXII_6">VI</a>. <i>Influence of the sun and moon on + diseases. The chemical stimulus of the blood. Menstruation obeys the + lunations. Queries.</i> <a href="#sect_XXXII_7">VII</a>. <i>Quiesence of + large glands a cause of fever. Swelling of the præcordia.</i> <a + href="#sect_XXXII_8">VIII</a>. <i>Other causes of quiescence, as hunger, + bad air, fear, anxiety.</i> <a href="#sect_XXXII_9">IX</a>. <a + href="#sect_XXXII_9_1">1</a>. <i>Symptoms of the cold fit.</i> <a + href="#sect_XXXII_9_2">2</a>. <i>Of the hot fit.</i> <a + href="#sect_XXXII_9_3">3</a>. <i>Second cold fit why.</i> <a + href="#sect_XXXII_9_4">4</a>. <i>Inflammation introduced, or delirium, or + stupor.</i> <a href="#sect_XXXII_10">X</a>. <i>Recapitulation. Fever not + an effort of nature to relieve herself. Doctrine of spasm.</i></p> + +</blockquote> + + <p><a name="sect_XXXII_1">I</a>. When the contractile sides of the heart + and arteries perform a greater number of pulsations in a given time, and + move through a greater area at each pulsation, whether these motions are + occasioned by the stimulus of the acrimony or quantity of the blood, or + by their association with other irritative motions, or by the increased + irritability of the arterial system, that is, by an increased quantity of + sensorial power, one kind of fever is produced; which may be called + Synocha irritativa, or Febris irritativa pulsu forti, or irritative fever + with strong pulse.</p> + + <p>When the contractile sides of the heart and arteries perform a greater + number of pulsations in a given time, but move through a much less area + at each pulsation, whether these motions are occasioned by defect of + their natural stimuli, or by the defect of other irritative motions with + which they are associated, or from the inirritability of the arterial + system, that is, from a decreased quantity of sensorial power, another + kind of fever arises; which may be termed, Typhus irritativus, or Febris + irritativa pulsu debili, or irritative fever with weak pulse. The former + of these fevers is the synocha of nosologists, and the latter the typhus + mitior, or nervous fever. In the former there appears to be an increase + of sensorial power, in the latter a deficiency of it; which is shewn to + be the immediate cause of strength and weakness, as defined in Sect. <a + href="#sect_XII_1_3">XII. 1. 3</a>.</p> + + <p>It should be added, that a temporary quantity of strength or debility + may be induced by the defect or excess of stimulus above what is natural; + and that in the same fever <i>debility always exists during the cold fit, + though strength does not always exist during the hot fit.</i></p> + + <p>These fevers are always connected with, and generally induced by, the + disordered irritative motions of the organs of sense, or of the + intestinal canal, or of the glandular system, or of the absorbent system; + and hence are always complicated with some or many of these disordered + motions, which are termed the symptoms of the fever, and which compose + the great variety in these diseases.</p> + + <p>The irritative fevers both with strong and with weak pulse, as well as + the sensitive fevers with strong and with weak pulse, which are to be + described in the next section, are liable to periodical remissions, and + then they take the name of intermittent fevers, and are distinguished by + the periodical times of their access.</p> + + <p><a name="sect_XXXII_2">II</a>. For the better illustration of the + phenomena of irritative fevers we must refer the reader to the + circumstances of irritation explained in Sect. <a + href="#sect_XII">XII</a>. and shall commence this intricate subject by + speaking of the quick pulse, and proceed by considering many of the + causes, which either separately or in combination most frequently produce + the cold fits of fevers.</p> + + <p><a name="sect_XXXII_2_1">1</a>. If the arteries are dilated but to + half their usual diameters, though they contract twice as frequently in a + given time, they will circulate only half their usual quantity of blood: + for as they are cylinders, the blood which they contain must be as the + squares of their diameters. Hence when the pulse becomes quicker and + smaller in the same proportion, the heart and arteries act with less + energy than in their natural state. See Sect. <a + href="#sect_XII_1_4">XII. 1. 4</a>.</p> + + <p>That this quick small pulse is owing to want of irritability, appears, + first, because it attends other symptoms of want of irritability; and, + secondly, because on the application of a stimulus greater than usual, it + becomes slower and larger. Thus in cold fits of agues, in hysteric + palpitations of the heart, and when the body is much exhausted by + hæmorrhages, or by fatigue, as well as in nervous fevers, the pulse + becomes quick and small; and secondly, in all those cases if an increase + of stimulus be added, by giving a little wine or opium; the quick small + pulse becomes slower and larger, as any one may easily experience on + himself, by counting his pulse after drinking one or two glasses of wine, + when he is faint from hunger or fatigue.</p> + + <p>Now nothing can so strongly evince that this quick small pulse is + owing to defect of irritability, than that an additional stimulus, above + what is natural, makes it become slower and larger immediately: for what + is meant by a defect of irritability, but that the arteries and heart are + not excited into their usual exertions by their usual quantity of + stimulus? but if you increase the quantity of stimulus, and they + immediately act with their usual energy, this proves their previous want + of their natural degree of irritability. Thus the trembling hands of + drunkards in a morning become steady, and acquire strength to perform + their usual offices, by the accustomed stimulus of a glass or two of + brandy.</p> + + <p><a name="sect_XXXII_2_2">2</a>. In sleep and in apoplexy the pulse + becomes slower, which is not owing to defect of irritability, for it is + at the same time larger; and thence the quantity of the circulation is + rather increased than diminished. In these cases the organs of sense are + closed, and the voluntary power is suspended, while the motions dependent + on internal irritations, as those of digestion and secretion, are carried + on with more than their usual vigour; which has led superficial observers + to confound these cases with those arising from want of irritability. + Thus if you lift up the eyelid of an apoplectic patient, who is not + actually dying, the iris will, as usual, contract itself, as this motion + is associated with the stimulus of light; but it is not so in the last + stages of nervous fevers, where the pupil of the eye continues expanded + in the broad day-light: in the former case there is a want of voluntary + power, in the latter a want of irritability.</p> + + <p>Hence also those constitutions which are deficient in quantity of + irritability, and which possess too great sensibility, as during the pain + of hunger, of hysteric spasms, or nervous headachs, are generally + supposed to have too much irritability; and opium, which in its due dose + is a most powerful stimulant, is erroneously called a sedative; because + by increasing the irritative motions it decreases the pains arising from + defect of them.</p> + + <p>Why the pulse should become quicker both from an increase of + irritation, as in the synocha irritativa, or irritative fever with strong + pulse; and from the decrease of it, as in the typhus irritativus, or + irritative fever with weak pulse; seems paradoxical. The former + circumstance needs no illustration; since if the stimulus of the blood, + or the irritability of the sanguiferous system be increased, and the + strength of the patient not diminished, it is plain that the motions must + be performed quicker and stronger.</p> + + <p>In the latter circumstance the weakness of the muscular power of the + heart is soon over-balanced by the elasticity of the coats of the + arteries, which they possess besides a muscular power of contraction; and + hence the arteries are distended to less than their usual diameters. The + heart being thus stopped, when it is but half emptied, begins sooner to + dilate again; and the arteries being dilated to less than their usual + diameters, begin so much sooner to contract themselves; insomuch, that in + the last stages of fevers with weakness the frequency of pulsation of the + heart and arteries becomes doubled; which, however, is never the case in + fevers with strength, in which they seldom exceed 118 or 120 pulsations + in a minute. It must be added, that in these cases, while the pulse is + very small and very quick, the heart often feels large, and labouring to + one's hand; which coincides with the above explanation, shewing that it + does not completely empty itself.</p> + + <p><a name="sect_XXXII_2_3">3</a>. In cases however of debility from + paucity of blood, as in animals which are bleeding to death in the + slaughter-house, the quick pulsations of the heart and arteries may be + owing to their not being distended to more than half their usual + diastole; and in consequence they must contract sooner, or more + frequently, in a given time. As weak people are liable to a deficient + quantity of blood, this cause may occasionally contribute to quicken the + pulse in fevers with debility, which may be known by applying one's hand + upon the heart as above; but the principal cause I suppose to consist in + the diminution of sensorial power. When a muscle contains, or is supplied + with but little sensorial power, its contraction soon ceases, and in + consequence may soon recur, as is seen in the trembling hands of people + weakened by age or by drunkenness. See Sect. <a href="#sect_XII_1_4">XII. + 1. 4</a>. <a href="#sect_XII_3_4">XII. 3. 4</a>.</p> + + <p>It may nevertheless frequently happen, that both the deficiency of + stimulus, as where the quantity of blood is lessened (as described in No. + <a href="#sect_XXXII_4">4</a>. of this section), and the deficiency of + sensorial power, as in those of the temperament of irritability, + described in Sect. <a href="#sect_XXXI">XXXI</a>. occur at the same time; + which will thus add to the quickness of the pulse and to the danger of + the disease.</p> + + <p><a name="sect_XXXII_3">III</a>. <a name="sect_XXXII_3_1">1</a>. A + certain degree of heat is necessary to muscular motion, and is, in + consequence, essential to life. This is observed in those animals and + insects which pass the cold season in a torpid state, and which revive on + being warmed by the fire. This necessary stimulus of heat has two + sources; one from the fluid atmosphere of heat, in which all things are + immersed, and the other from the internal combinations of the particles, + which form the various fluids, which are produced in the extensive + systems of the glands. When either the external heat, which surrounds us, + or the internal production of it, becomes lessened to a certain degree, + the pain of cold is perceived.</p> + + <p>This pain of cold is experienced most sensibly by our teeth, when ice + is held in the mouth; or by our whole system after having been previously + accustomed to much warmth. It is probable, that this pain does not arise + from the mechanical or chemical effects of a deficiency of heat; but + that, like the organs of sense by which we perceive hunger and thirst, + this sense of heat suffers pain, when the stimulus of its object is + wanting to excite the irritative motions of the organ; that is, when the + sensorial power becomes too much accumulated in the quiescent fibres. See + Sect. <a href="#sect_XII_5_3">XII. 5. 3</a>. For as the peristaltic + motions of the stomach are lessened, when the pain of hunger is great, so + the action of the cutaneous capillaries are lessened during the pain of + cold; as appears by the paleness of the skin, as explained in Sect. <a + href="#sect_XIV_6">XIV. 6</a>. on the production of ideas.</p> + + <p>The pain in the small of the back and forehead in the cold fits of the + ague, in nervous hemicrania, and in hysteric paroxysms, when all the + irritative motions are much impaired, seems to arise from this cause; the + vessels of these membranes or muscles become torpid by their irritative + associations with other parts of the body, and thence produce less of + their accustomed secretions, and in consequence less heat is evolved, and + they experience the pain of cold; which coldness may often be felt by the + hand applied upon the affected part.</p> + + <p><a name="sect_XXXII_3_2">2</a>. The importance of a greater or less + deduction of heat from the system will be more easy to comprehend, if we + first consider the great expense of sensorial power used in carrying on + the vital motions; that is, which circulates, absorbs, secretes, aerates, + and elaborates the whole mass of fluids with unceasing assiduity. The + sensorial power, or spirit of animation, used in giving perpetual and + strong motion to the heart, which overcomes the elasticity and vis + inertiæ of the whole arterial system; next the expense of sensorial power + in moving with great force and velocity the innumerable trunks and + ramifications of the arterial system; the expense of sensorial power in + circulating the whole mass of blood through the long and intricate + intortions of the very fine vessels, which compose the glands and + capillaries; then the expense of sensorial power in the exertions of the + absorbent extremities of all the lacteals, and of all the lymphatics, + which open their mouths on the external surface of the skin, and on the + internal surfaces of every cell or interstice of the body; then the + expense of sensorial power in the venous absorption, by which the blood + is received from the capillary vessels, or glands, where the arterial + power ceases, and is drank up, and returned to the heart; next the + expense of sensorial power used by the muscles of respiration in their + office of perpetually expanding the bronchia, or air-vessels, of the + lungs; and lastly in the unceasing peristaltic motions of the stomach and + whole system of intestines, and in all the secretions of bile, gastric + juice, mucus, perspirable matter, and the various excretions from the + system. If we consider the ceaseless expense of sensorial power thus + perpetually employed, it will appear to be much greater in a day than all + the voluntary exertions of our muscles and organs of sense consume in a + week; and all this without any sensible fatigue! Now, if but a part of + these vital motions are impeded, or totally stopped for but a short time, + we gain an idea, that there must be a great accumulation of sensorial + power; as its production in these organs, which are subject to perpetual + activity, is continued during their quiescence, and is in consequence + accumulated.</p> + + <p>While, on the contrary, where those vital organs act too forcibly by + increase of stimulus without a proportionally-increased production of + sensorial power in the brain, it is evident, that a great deficiency of + action, that is torpor, must soon follow, as in fevers; whereas the + locomotive muscles, which act only by intervals, are neither liable to so + great accumulation of sensorial power during their times of inactivity, + nor to so great an exhaustion of it during their times of action.</p> + + <p>Thus, on going into a very cold bath, suppose at 33 degrees of heat on + Fahrenheit's scale, the action of the subcutaneous capillaries, or + glands, and of the mouths of the cutaneous absorbents is diminished, or + ceases for a time. Hence less or no blood passes these capillaries, and + paleness succeeds. But soon after emerging from the bath, a more florid + colour and a greater degree of heat is generated on the skin than was + possessed before immersion; for the capillary glands, after this + quiescent state, occasioned by the want of stimulus, become more + irritable than usual to their natural stimuli, owing to the accumulation + of sensorial power, and hence a greater quantity of blood is transmitted + through them, and a greater secretion of perspirable matter; and, in + consequence, a greater degree of heat succeeds. During the continuance in + cold water the breath is cold, and the act of respiration quick and + laborious; which have generally been ascribed to the obstruction of the + circulating fluid by a spasm of the cutaneous vessels, and by a + consequent accumulation of blood in the lungs, occasioned by the pressure + as well as by the coldness of the water. This is not a satisfactory + account of this curious phænomenon, since at this time the whole + circulation is less, as appears from the smallness of the pulse and + coldness of the breath; which shew that less blood passes through the + lungs in a given time; the same laborious breathing immediately occurs + when the paleness of the skin is produced by fear, where no external cold + or pressure are applied.</p> + + <p>The minute vessels of the bronchia, through which the blood passes + from the arterial to the venal system, and which correspond with the + cutaneous capillaries, have frequently been exposed to cold air, and + become quiescent along with those of the skin; and hence their motions + are so associated together, that when one is affected either with + quiescence or exertion, the other sympathizes with it, according to the + laws of irritative association. See Sect. <a href="#sect_XXVII_1">XXVII. + 1</a>. on hæmorrhages.</p> + + <p>Besides the quiescence of the minute vessels of the lungs, there are + many other systems of vessels which become torpid from their irritative + associations with those of the skin, as the absorbents of the bladder and + intestines; whence an evacuation of pale urine occurs, when the naked + skin is exposed only to the coldness of the atmosphere; and sprinkling + the naked body with cold water is known to remove even pertinacious + constipation of the bowels. From the quiescence of such extensive systems + of vessels as the glands and capillaries of the skin, and the minute + vessels of the lungs, with their various absorbent series of vessels, a + great accumulation of sensorial powers is occasioned; part of which is + again expended in the increased exertion of all these vessels, with an + universal glow of heat in consequence of this exertion, and the remainder + of it adds vigour to both the vital and voluntary exertions of the whole + day.</p> + + <p>If the activity of the subcutaneous vessels, and of those with which + their actions are associated, was too great before cold immersion, as in + the hot days of summer, and by that means the sensorial power was + previously diminished, we see the cause why the cold bath gives such + present strength; namely, by stopping the unnecessary activity of the + subcutaneous vessels, and thus preventing the too great exhaustion of + sensorial power; which, in metaphorical language, has been called + <i>bracing</i> the system: which is, however, a mechanical term, only + applicable to drums, or musical strings: as on the contrary the word + <i>relaxation</i>, when applied to living animal bodies, can only mean + too small a quantity of stimulus, or too small a quantity of sensorial + power; as explained in Sect. <a href="#sect_XII_1">XII. 1</a>.</p> + + <p><a name="sect_XXXII_3_3">3</a>. This experiment of cold bathing + presents us with a simple fever-fit; for the pulse is weak, small, and + quick during the cold immersion; and becomes strong, full, and quick + during the subsequent glow of heat; till in a few minutes these symptoms + subside, and the temporary fever ceases.</p> + + <p>In those constitutions where the degree of inirritability, or of + debility, is greater than natural, the coldness and paleness of the skin + with the quick and weak pulse continue a long time after the patient + leaves the bath; and the subsequent heat approaches by unequal flushings, + and he feels himself disordered for many hours. Hence the bathing in a + cold spring of water, where the heat is but forty-eight degrees on + Fahrenheit's thermometer, much disagrees with those of weak or + inirritable habits of body; who possess so little sensorial power, that + they cannot without injury bear to have it diminished even for a short + time; but who can nevertheless bear the more temperate coldness of Buxton + bath, which is about eighty degrees of heat, and which strengthens them, + and makes them by habit less liable to great quiescence from small + variations of cold, and thence less liable to be disordered by the + unavoidable accidents of life. Hence it appears, why people of these + inirritable constitutions, which is another expression for sensorial + deficiency, are often much injured by bathing in a cold spring of water; + and why they should continue but a very short time in baths, which are + colder than their bodies; and should gradually increase both the degree + of coldness of the water, and the time of their continuance in it, if + they would obtain salutary effects from cold immersions. See Sect. <a + href="#sect_XII_2_1">XII. 2. 1</a>.</p> + + <p>On the other hand, in all cases where the heat of the external surface + of the body, or of the internal surface of the lungs, is greater than + natural, the use of exposure to cool air may be deduced. In fever-fits + attended with strength, that is with great quantity of sensorial power, + it removes the additional stimulus of heat from the surfaces above + mentioned, and thus prevents their excess of useless motion; and in + fever-fits attended with debility, that is with a deficiency of the + quantity of sensorial power, it prevents the great and dangerous waste of + sensorial power expended in the unnecessary increase of the actions of + the glands and capillaries of the skin and lungs.</p> + + <p><a name="sect_XXXII_3_4">4</a>. In the same manner, when any one is + long exposed to very cold air, a quiescence is produced of the cutaneous + and pulmonary capillaries and absorbents, owing to the deficiency of + their usual stimulus of heat; and this quiescence of so great a quantity + of vessels affects, by irritative association, the whole absorbent and + glandular system, which becomes in a greater or less degree quiescent, + and a cold fit of fever is produced.</p> + + <p>If the deficiency of the stimulus of heat is very great, the + quiescence becomes so general as to extinguish life, as in those who are + frozen to death.</p> + + <p>If the deficiency of heat be in less degree, but yet so great as in + some measure to disorder the system, and should occur the succeeding day, + it will induce a greater degree of quiescence than before, from its + acting in concurrence with the period of the diurnal circle of actions, + explained in Sect. <a href="#sect_XXXVI">XXXVI</a>. Hence from a small + beginning a greater and greater degree of quiescence 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 Sect. <a + href="#sect_XVII_3_6">XVII. 3. 6</a>.</p> + + <p>If the degree of quiescence occasioned by defect of the stimulus of + heat be very great, it will recur a second time by a slighter cause, than + that which first induced it. If the cause, which induces the second fit + of quiescence, recurs the succeeding day, the quotidian fever is + produced; if not till the alternate day, the tertian fever; and if not + till after seventy-two hours from the first fit of quiescence, the + quartan fever is formed. This last kind of fever recurs less frequently + than the other, as it is a disease only of those of the temperament of + associability, as mentioned in Sect. <a href="#sect_XXXI">XXXI</a>.; for + in other constitutions the capability of forming a habit ceases, before + the new cause of quiescence is again applied, if that does not occur + sooner than in seventy-two hours.</p> + + <p>And hence those fevers, whose cause is from cold air of the night or + morning, are more liable to observe the solar day in their periods; while + those from other causes frequently observe the lunar day in their + periods, their paroxysms returning near an hour later every day, as + explained in Sect. <a href="#sect_XXXVI">XXXVI</a>.</p> + + <p><a name="sect_XXXII_4">IV</a>. Another frequent cause of the cold fits + of fever is the defect of the stimulus of distention. The whole arterial + system would appear, by the experiments of Haller, to be irritable by no + other stimulus, and the motions of the heart and alimentary canal are + certainly in some measure dependant on the same cause. See Sect. <a + href="#sect_XIV_7">XIV. 7</a>. Hence there can be no wonder, that the + diminution of distention should frequently induce the quiescence, which + constitutes the beginning of fever-fits.</p> + + <p>Monsieur Leiutaud has judiciously mentioned the deficiency of the + quantity of blood amongst the causes of diseases, which he says is + frequently evident in dissections: fevers are hence brought on by great + hæmorrhages, diarrhœas, or other evacuations; or from the continued + use of diet, which contains but little nourishment; or from the + exhaustion occasioned by violent fatigue, or by those chronic diseases in + which the digestion is much impaired; as where the stomach has been long + affected with the gout or schirrus; or in the paralysis of the liver, as + described in Sect. <a href="#sect_XXX">XXX</a>. Hence a paroxysm of gout + is liable to recur on bleeding or purging; as the torpor of some viscus, + which precedes the inflammation of the foot, is thus induced by the want + of the stimulus of distention. And hence the extremities of the body, as + the nose and fingers, are more liable to become cold, when we have long + abstained from food; and hence the pulse is increased both in strength + and velocity above the natural standard after a full meal by the stimulus + of distention.</p> + + <p>However, this stimulus of distention, like the stimulus of heat above + described, though it contributes much to the due action not only of the + heart, arteries, and alimentary canal, but seems necessary to the proper + secretion of all the various glands; yet perhaps it is not the sole cause + of any of these numerous motions: for as the lacteals, cutaneous + absorbents, and the various glands appear to be stimulated into action by + the peculiar pungency of the fluids they absorb, so in the intestinal + canal the pungency of the digesting aliment, or the acrimony of the + fæces, seem to contribute, as well as their bulk, to promote the + peristaltic motions; and in the arterial system, the momentum of the + particles of the circulating blood, and their acrimony, stimulate the + arteries, as well as the distention occasioned by it. Where the pulse is + small this defect of distention is present, and contributes much to + produce the febris irritativa pulsu debili, or irritative fever with weak + pulse, called by modern writers nervous fever, as a predisponent cause. + See Sect. <a href="#sect_XII_1_4">XII. 1. 4</a>. Might not the + transfusion of blood, suppose of four ounces daily from a strong man, or + other healthful animal, as a sheep or an ass, be used in the early state + of nervous or putrid fevers with great prospect of success?</p> + + <p><a name="sect_XXXII_5">V</a>. <a name="sect_XXXII_5_1">1</a>. The + defect of the momentum of the particles of the circulating blood is + another cause of the quiescence, with which the cold fits of fever + commence. This stimulus of the momentum of the progressive particles of + the blood does not act over the whole body like those of heat and + distention above described, but is confined to the arterial system; and + differs from the stimulus of the distention of the blood, as much as the + vibration of the air does from the currents of it. Thus are the different + organs of our bodies stimulated by four different mechanic properties of + the external world: the sense of touch by the pressure of solid bodies so + as to distinguish their figure; the muscular system by the distention, + which they occasion; the internal surface of the arteries, by the + momentum of their moving particles; and the auditory nerves, by the + vibration of them: and these 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 sense.</p> + + <p><a name="sect_XXXII_5_2">2</a>. The momentum of the progressive + particles of blood is compounded of their velocity and their quantity of + matter: hence whatever circumstances diminish either of these without + proportionally increasing the other, and without superadding either of + the general stimuli of heat or distention, will tend to produce a + quiescence of the arterial system, and from thence of all the other + irritative motions, which are connected with it.</p> + + <p>Hence in all those constitutions or diseases where the blood contains + a greater proportion of serum, which is the lightest part of its + composition, the pulsations of the arteries are weaker, as in nervous + fevers, chlorosis, and hysteric complaints; for in these cases the + momentum of the progressive particles of blood is less: and hence, where + the denser parts of its composition abound, as the red part of it, or the + coagulable lymph, the arterial pulsations are stronger; as in those of + robust health, and in inflammatory diseases.</p> + + <p>That this stimulus of the momentum of the particles of the circulating + fluid is of the greatest consequence to the arterial action, appears from + the experiment of injecting air into the blood vessels, which seems to + destroy animal life from the want of this stimulus of momentum; for the + distention of the arteries is not diminished by it, it possesses no + corrosive acrimony, and is less liable to repass the valves than the + blood itself; since air-valves in all machinery require much less + accuracy of construction than those which are opposed to water.</p> + + <p><a name="sect_XXXII_5_3">3</a>. One method of increasing the velocity + of the blood, and in consequence the momentum of its particles, is by the + exercise of the body, or by the friction of its surface: so, on the + contrary, too great indolence contributes to decrease this stimulus of + the momentum of the particles of the circulating blood, and thus tends to + induce quiescence; as is seen in hysteric cases, and chlorosis, and the + other diseases of sedentary people.</p> + + <p><a name="sect_XXXII_5_4">4</a>. The velocity of the particles of the + blood in certain circumstances is increased by venesection, which, by + removing a part of it, diminishes the resistance to the motion of the + other part, and hence the momentum of the particles of it is increased. + This may be easily understood by considering it in the extreme, since, if + the resistance was greatly increased, so as to overcome the propelling + power, there could be no velocity, and in consequence no momentum at all. + From this circumstance arises that curious phænomenon, the truth of which + I have been more than once witness to, that venesection will often + instantaneously relieve those nervous pains, which attend the cold + periods of hysteric, asthmatic, or epileptic diseases; and that even + where large doses of opium have been in vain exhibited. In these cases + the pulse becomes stronger after the bleeding, and the extremities regain + their natural warmth; and an opiate then given acts with much more + certain effect.</p> + + <p><a name="sect_XXXII_6">VI</a>. There is another cause, which seems + occasionally to induce quiescence into some part of our system, I mean + the influence of the sun and moon; the attraction of these luminaries, by + decreasing the gravity of the particles of the blood, cannot affect their + momentum, as their vis inertiæ remains the same; but it may nevertheless + produce some chemical change in them, because whatever affects the + general attractions of the particles of matter may be supposed from + analogy to affect their specific attractions or affinities: and thus the + stimulus of the particles of blood may be diminished, though not their + momentum. As the tides of the sea obey the southing and northing of the + moon (allowing for the time necessary for their motion, and the + obstructions of the shores), it is probable, that there are also + atmospheric tides on both sides of the earth, which to the inhabitants of + another planet might so deflect the light as to resemble the ring of + Saturn. Now as these tides of water, or of air, are raised by the + diminution of their gravity, it follows, that their pressure on the + surface of the earth is no greater than the pressure of the other parts + of the ocean, or of the atmosphere, where no such tides exist; and + therefore that they cannot affect the mercury in the barometer. In the + same manner, the gravity of all other terrestrial bodies is diminished at + the times of the southing and northing of the moon, and that in a greater + degree when this coincides with the southing and northing of the sun, and + this in a still greater degree about the times of the equinoxes. This + decrease of the gravity of all bodies during the time the moon passes our + zenith or nadir might possibly be shewn by the slower vibrations of a + pendulum, compared with a spring clock, or with astronomical observation. + Since a pendulum of a certain length moves slower at the line than near + the poles, because the gravity being diminished and the vis inertiæ + continuing the same, the motive power is less, but the resistance to be + overcome continues the same. The combined powers of the lunar and solar + attraction is estimated by Sir Isaac Newton not to exceed one 7,868,850th + part of the power of gravitation, which seems indeed but a small + circumstance to produce any considerable effect on the weight of + sublunary bodies, and yet this is sufficient to raise the tides at the + equator above ten feet high; and if it be considered, what small impulses + of other bodies produce their effects on the organs of sense adapted to + the perception of them, as of vibration on the auditory nerves, we shall + cease to to be surprised, that so minute a diminution in the gravity of + the particles of blood should so far affect their chemical changes, or + their stimulating quality, as, joined with other causes, sometimes to + produce the beginnings of diseases.</p> + + <p>Add to this, that if the lunar influence produces a very small degree + of quiescence at first, and if that recurs at certain periods even with + less power to produce quiescence than at first, yet the quiescence will + daily increase by the acquired habit acting at the same time, till at + length so great a degree of quiescence is induced as to produce phrensy, + canine madness, epilepsy, hysteric pains or cold fits of fever, instances + of many of which are to be found in Dr. Mead's work on this subject. The + solar influence also appears daily in several diseases; but as darkness, + silence, sleep, and our periodical meals mark the parts of the solar + circle of actions, it is sometimes dubious to which of these the + periodical returns of these diseases are to be ascribed.</p> + + <p>As far as I have been able to observe, the periods of inflammatory + diseases observe the solar day; as the gout and rheumatism have their + greatest quiescence about noon and midnight, and their exacerbations some + hours after; as they have more frequently their immediate cause from cold + air, inanition, or fatigue, than from the effects of lunations: whilst + the cold fits of hysteric patients, and those in nervous fevers, more + frequently occur twice a day, later by near half an hour each time, + according to the lunar day; whilst some fits of intermittents, which are + undisturbed by medicines, return at regular solar periods, and others at + lunar ones; which may, probably, be owing to the difference of the + periods of those external circumstances of cold, inanition, or lunation, + which immediately caused them.</p> + + <p>We must, however, observe, that the periods of quiescence and + exacerbation in diseases do not always commence at the times of the + syzygies or quadratures of the moon and sun, or at the times of their + passing the zenith or nadir; but as it is probable, that the stimulus of + the particles of the circumfluent blood is gradually diminished from the + time of the quadratures to that of the syzygies, the quiescence may + commence at any hour, when co-operating with other causes of quiescence, + it becomes great enough to produce a disease: afterwards it will continue + to recur at the same period of the lunar or solar influence; the same + cause operating conjointly with the acquired habit, that is with the + catenation of this new motion with the dissevered links of the lunar or + solar circles of animal action.</p> + + <p>In this manner the periods of menstruation obey the lunar month with + great exactness in healthy patients (and perhaps the venereal orgasm in + brute animals does the same), yet these periods do not commence either at + the syzygies or quadratures of the lunations, but at whatever time of the + lunar periods they begin, they observe the same in their returns till + some greater cause disturbs them.</p> + + <p>Hence, though the best way to calculate the time of the expected + returns of the paroxysms of periodical diseases is to count the number of + hours between the commencement of the two preceding fits, yet the + following observations may be worth attending to, when we endeavour to + prevent the returns of maniacal or epileptic diseases; whose periods (at + the beginning of them especially) frequently observe the syzygies of the + moon and sun, and particularly about the equinox.</p> + + <p>The greatest of the two tides happening in every revolution of the + moon, is that when the moon approaches nearest to the zenith or nadir; + for this reason, while the sun is in the northern signs, that is during + the vernal and summer months, the greater of the two diurnal tides in our + latitude is that, when the moon is above the horizon; and when the sun is + in the southern signs, or during the autumnal and winter months, the + greater tide is that, which arises when the moon is below the horizon: + and as the sun approaches somewhat nearer the earth in winter than in + summer, the greatest equinoctial tides are observed to be a little before + the vernal equinox, and a little after the autumnal one.</p> + + <p>Do not the cold periods of lunar diseases commence a few hours before + the southing of the moon during the vernal and summer months, and before + the northing of the moon during the autumnal and winter months? Do not + palsies and apoplexies, which occur about the equinoxes, happen a few + days before the vernal equinoctial lunation, and after the autumnal one? + Are not the periods of those diurnal diseases more obstinate, that + commence many hours before the southing or northing of the moon, than of + those which commence at those times? Are not those palsies and apoplexies + more dangerous which commence many days before the syzygies of the moon, + than those which happen at those times? See Sect. <a + href="#sect_XXXVI">XXXVI</a>. on the periods of diseases.</p> + + <p><a name="sect_XXXII_7">VII</a>. Another very frequent cause of the + cold fit of fever is the quiescence of some of those large congeries of + glands, which compose the liver, spleen, or pancreas; one or more of + which are frequently so enlarged in the autumnal intermittents as to be + perceptible to the touch externally, and are called by the vulgar + ague-cakes. As these glands are stimulated into action by the specific + pungency of the fluids, which they absorb, the general cause of their + quiescence seems to be the too great insipidity of the fluids of the + body, co-operating perhaps at the same time with other general causes of + quiescence.</p> + + <p>Hence, in marshy countries at cold seasons, which have succeeded hot + ones, and amongst those, who have lived on innutritious and unstimulating + diet, these agues are most frequent. The enlargement of these quiescent + viscera, and the swelling of the præcordia in many other fevers, is, most + probably, owing to the same cause; which may consist in a general + deficiency of the production of sensorial power, as well as in the + diminished stimulation of the fluids; and when the quiescence of so great + a number of glands, as constitute one of those large viscera, commences, + all the other irritative motions are affected by their connection with + it, and the cold fit of fever is produced.</p> + + <p><a name="sect_XXXII_8">VIII</a>. There are many other causes, which + produce quiescence of some part of the animal system, as fatigue, hunger, + thirst, bad diet, disappointed love, unwholesome air, exhaustion from + evacuations, and many others; but the last cause, that we shall mention, + as frequently productive of cold fits of fever, is fear or anxiety of + mind. The pains, which we are first and most generally acquainted with, + have been produced by defect of some stimulus; thus, soon after our + nativity we become acquainted with the pain from the coldness of the air, + from the want of respiration, and from the want of food. Now all these + pains occasioned by defect of stimulus are attended with quiescence of + the organ, and at the same time with a greater or less degree of + quiescence of other parts of the system: thus, if we even endure the pain + of hunger so as to miss one meal instead of our daily habit of repletion, + not only the peristaltic motions of the stomach and bowels are + diminished, but we are more liable to coldness of our extremities, as of + our noses, and ears, and feet, than at other times.</p> + + <p>Now, as fear is originally excited by our having experienced pain, and + is itself a painful affection, the same quiescence of other fibrous + motions accompany it, as have been most frequently connected with this + kind of pain, as explained in Sect. <a href="#sect_XVI_8_1">XVI. 8. + 1</a>. as the coldness and paleness of the skin, trembling, difficult + respiration, indigestion, and other symptoms, which contribute to form + the cold fit of fevers. Anxiety is fear continued through a longer time, + and, by producing chronical torpor of the system, extinguishes life + slowly, by what is commonly termed a broken heart.</p> + + <p><a name="sect_XXXII_9">IX</a>. <a name="sect_XXXII_9_1">1</a>. We now + step forwards to consider the other symptoms in consequence of the + quiescence which begins the fits of fever. If by any of the circumstances + before described, or by two or more of them acting at the same time, a + great degree of quiescence is induced on any considerable part of the + circle of irritative motions, the whole class of them is more or less + disturbed by their irritative associations. If this torpor be occasioned + by a deficient supply of sensorial power, and happens to any of those + parts of the system, which are accustomed to perpetual activity, as the + vital motions, the torpor increases rapidly, because of the great + expenditure of sensorial power by the incessant activity of those parts + of the system, as shewn in No. <a href="#sect_XXXII_3_2">3. 2</a>. of + this Section. Hence a deficiency of all the secretions succeeds, and as + animal heat is produced in proportion to the quantity of those + secretions, the coldness of the skin is the first circumstance, which is + attended to. Dr. Martin asserts, that some parts of his body were warmer + than natural in the cold fit of fever; but it is certain, that those, + which are uncovered, as the fingers, and nose, and ears, are much colder + to the touch, and paler in appearance. It is possible, that his + experiments were made at the beginning of the subsequent hot fits; which + commence with partial distributions of heat, owing to some parts of the + body regaining their natural irritability sooner than others.</p> + + <p>From the quiescence of the anastomosing capillaries a paleness of the + skin succeeds, and a less secretion of the perspirable matter; from the + quiescence of the pulmonary capillaries a difficulty of respiration + arises; and from the quiescence of the other glands less bile, less + gastric and pancreatic juice, are secreted into the stomach and + intestines, and less mucus and saliva are poured into the mouth; whence + arises the dry tongue, costiveness, dry ulcers, and paucity of urine. + From the quiescence of the absorbent system arises the great thirst, as + less moisture is absorbed from the atmosphere. The absorption from the + atmosphere was observed by Dr. Lyster to amount to eighteen ounces in one + night, above what he had at the same time insensibly perspired. See + Langrish. On the same account the urine is pale, though in small + quantity, for the thinner part is not absorbed from it; and when repeated + ague-fits continue long, the legs swell from the diminished absorption of + the cellular absorbents.</p> + + <p>From the quiescence of the intestinal canal a loss of appetite and + flatulencies proceed. From the partial quiescence of the glandular + viscera a swelling and tension about the præcordia becomes sensible to + the touch; which is occasioned by the delay of the fluids from the defect + of venous or lymphatic absorption. The pain of the forehead, and of the + limbs, and of the small of the back, arises from the quiescence of the + membranous fascia, or muscles of those parts, in the same manner as the + skin becomes painful, when the vessels, of which it is composed, become + quiescent from cold. The trembling in consequence of the pain of + coldness, the restlessness, and the yawning, and stretching of the limbs, + together with the shuddering, or rigours, are convulsive motions; and + will be explained amongst the diseases of volition; Sect. <a + href="#sect_XXXIV">XXXIV</a>.</p> + + <p>Sickness and vomiting is a frequent symptom in the beginnings of + fever-fits, the muscular fibres of the stomach share the general torpor + and debility of the system; their motions become first lessened, and then + stop, and then become retrograde; for the act of vomiting, like the + globus hystericus and the borborigmi of hypochondriasis, is always a + symptom of debility, either from want of stimulus, as in hunger; or from + want of sensorial power, as after intoxication; or from sympathy with + some other torpid irritative motions, as in the cold fits of ague. See + Sect. <a href="#sect_XII_5_5">XII. 5. 5</a>. <a + href="#sect_XXIX_11">XXIX. 11</a>. and <a href="#sect_XXXV_1_3">XXXV. 1. + 3</a>. where this act of vomiting is further explained.</p> + + <p>The small pulse, which is said by some writers to be slow at the + commencement of ague-fits, and which is frequently trembling and + intermittent, is owing to the quiescence of the heart and arterial + system, and to the resistance opposed to the circulating fluid from the + inactivity of all the glands and capillaries. The great weakness and + inability to voluntary motions, with the insensibility of the + extremities, are owing to the general quiescence of the whole moving + system; or, perhaps, simply to the deficient production of sensorial + power.</p> + + <p>If all these symptoms are further increased, the quiescence of all the + muscles, including the heart and arteries, becomes complete, and death + ensues. This is, most probably, the case of those who are starved to + death with cold, and of those who are said to die in Holland from long + skaiting on their frozen canals.</p> + + <p><a name="sect_XXXII_9_2">2</a>. As soon as this general quiescence of + the system ceases, either by the diminution of the cause, or by the + accumulation of sensorial power, (as in syncope, Sect. <a + href="#sect_XII_7_1">XII. 7. 1</a>.) which is the natural consequence of + previous quiescence, the hot fit commences. Every gland of the body is + now stimulated into stronger action than is natural, as its irritability + is increased by accumulation of sensorial power during its late + quiescence, a superabundance of all the secretions is produced, and an + increase of heat in consequence of the increase of these secretions. The + skin becomes red, and the perspiration great, owing to the increased + action of the capillaries during the hot part of the paroxysm. The + secretion of perspirable matter is perhaps greater during the hot fit + than in the sweating fit which follows; but as the absorption of it also + is greater, it does not stand on the skin in visible drops: add to this, + that the evaporation of it also is greater, from the increased heat of + the skin. But at the decline of the hot fit, as the mouths of the + absorbents of the skin are exposed to the cooler air, or bed-clothes, + these vessels sooner lose their increased activity, and cease to absorb + more than their natural quantity: but the secerning vessels for some time + longer, being kept warm by the circulating blood, continue to pour out an + increased quantity of perspirable matter, which now stands on the skin in + large visible drops; the exhalation of it also being lessened by the + greater coolness of the skin, as well as its absorption by the diminished + action of the lymphatics. See Class I. 1. 2. 3.</p> + + <p>The increased secretion of bile and of other fluids poured into the + intestines frequently induce a purging at the decline of the hot fit; for + as the external absorbent vessels have their mouths exposed to the cold + air, as above mentioned, they cease to be excited into unnatural activity + sooner than the secretory vessels, whose mouths are exposed to the warmth + of the blood: now, as the internal absorbents sympathize with the + external ones, these also, which during the hot fit drank up the thinner + part of the bile, or of other secreted fluids, lose their increased + activity before the gland loses its increased activity, at the decline of + the hot fit; and the loose dejections are produced from the same cause, + that the increased perspiration stands on the surface of the skin, from + the increased absorption ceasing sooner than the increased secretion.</p> + + <p>The urine during the cold fit is in small quantity and pale, both from + a deficiency of the secretion and a deficiency of the absorption.</p> + + <p>During the hot fit it is in its usual quantity, but very high coloured + and turbid, because a greater quantity had been secreted by the increased + action of the kidnies, and also a greater quantity of its more aqueous + part had been absorbed from it in the bladder by the increased action of + the absorbents; and lastly, at the decline of the hot fit it is in large + quantity and less coloured, or turbid, because the absorbent vessels of + the bladder, as observed above, lose their increased action by sympathy + with the cutaneous ones sooner than the secretory vessels of the kidnies + lose their increased activity. Hence the quantity of the sediment, and + the colour of the urine, in fevers, depend much on the quantity secreted + by the kidnies, and the quantity absorbed from it again in the bladder: + the kinds of sediment, as the lateritious, purulent, mucous, or bloody + sediments, depend on other causes. It should be observed, that if the + sweating be increased by the heat of the room, or of the bed-clothes, + that a paucity of turbid urine will continue to be produced, as the + absorbents of the bladder will have their activity increased by their + sympathy with the vessels of the skin, for the purpose of supplying the + fluid expended in perspiration.</p> + + <p>The pulse becomes strong and full owing to the increased irritability + of the heart and arteries, from the accumulation of sensorial power + during their quiescence, and to the quickness of the return of the blood + from the various glands and capillaries. This increased action of all the + secretory vessels does not occur very suddenly, nor universally at the + same time. The heat seems to begin about the center, and to be diffused + from thence irregularly to the other parts of the system. This may be + owing to the situation of the parts which first became quiescent and + caused the fever-fit, especially when a hardness or tumour about the + præcordia can be felt by the hand; and hence this part, in whatever + viscus it is seated, might be the first to regain its natural or + increased irritability.</p> + + <p><a name="sect_XXXII_9_3">3</a>. It must be here noted, that, by the + increased quantity of heat, and of the impulse of the blood at the + commencement of the hot fit, a great increase of stimulus is induced, and + is now added to the increased irritability of the system, which was + occasioned by its previous quiescence. This additional stimulus of heat + and momentum of the blood augments the violence of the movements of the + arterial and glandular system in an increasing ratio. These violent + exertions still producing more heat and greater momentum of the moving + fluids, till at length the sensoral power becomes wasted by this great + stimulus beneath its natural quantity, and predisposes the system to a + second cold fit.</p> + + <p>At length all these unnatural exertions spontaneously subside with the + increased irritability that produced them; and which was itself produced + by the preceding quiescence, in the same manner as the eye, on coming + from darkness into day-light, in a little time ceases to be dazzled and + pained, and gradually recovers its natural degree of irritability.</p> + + <p><a name="sect_XXXII_9_4">4</a>. But if the increase of irritability, + and the consequent increase of the stimulus of heat and momentum, produce + more violent exertions than those above described; great pain arises in + some part of the moving system, as in the membranes of the brain, pleura, + or joints; and new motions of the vessels are produced in consequence of + this pain, which are called inflammation; or delirium or stupor arises; + as explained in Sect. <a href="#sect_XXI">XXI</a>. and <a + href="#sect_XXXIII">XXXIII</a>.: for the immediate effect is the same, + whether the great energy of the moving organs arises from an increase of + stimulus or an increase of irritability; though in the former case the + waste of sensorial power leads to debility, and in the latter to + health.</p> + +<p class="center" style="margin-top: 2em;"><i>Recapitulation.</i></p> + + <p><a name="sect_XXXII_10">X</a>. Those muscles, which are less + frequently exerted, and whose actions are interrupted by sleep, acquire + less accumulation of sensorial power during their quiescent state, as the + muscles of locomotion. In these muscles after great exertion, that is, + after great exhaustion of sensorial power, the pain of fatigue ensues; + and during rest there is a renovation of the natural quantity of + sensorial power; but where the rest, or quiescence of the muscle, is long + continued, a quantity of sensorial power becomes accumulated beyond what + is necessary; as appears by the uneasiness occasioned by want of + exercise; and which in young animals is one cause exciting them into + action, as is seen in the play of puppies and kittens.</p> + + <p>But when those muscles, which are habituated to perpetual actions, as + those of the stomach by the stimulus of food, those of the vessels of the + skin by the stimulus of heat, and those which constitute the arteries and + glands by the stimulus of the blood, become for a time quiescent, from + the want of their appropriated stimuli, or by their associations with + other quiescent parts of the system; a greater accumulation of sensorial + power is acquired during their quiescence, and a greater or quicker + exhaustion of it is produced during their increased action.</p> + + <p>This accumulation of sensorial power from deficient action, if it + happens to the stomach from want of food, occasions the pain of hunger; + if it happens to the vessels of the skin from want of heat, it occasions + the pain of cold; and if to the arterial system from the want of its + adapted stimuli, many disagreeable sensations are occasioned, such as are + experienced in the cold fits of intermittent fevers, and are as various, + as there are glands or membranes in the system, and are generally termed + universal uneasiness.</p> + + <p>When the quiescence of the arterial system is not owing to defect of + stimulus as above, but to the defective quantity of sensorial power, as + in the commencement of nervous fever, or irritative fever with weak + pulse, a great torpor of this system is quickly induced; because both the + irritation from the stimulus of the blood, and the association of the + vascular motions with each other, continue to excite the arteries into + action, and thence quickly exhaust the ill-supplied vascular muscles; for + to rest is death; and therefore those vascular muscles continue to + proceed, though with feebler action, to the extreme of weariness or + faintness: while nothing similar to this affects the locomotive muscles, + whose actions are generally caused by volition, and not much subject + either to irritation or to other kinds of associations besides the + voluntary ones, except indeed when they are excited by the lash of + slavery.</p> + + <p>In these vascular muscles, which are subject to perpetual action, and + thence liable to great accumulation of sensorial power during their + quiescence from want of stimulus, a great increase of activity occurs, + either from the renewal of their accustomed stimulus, or even from much + less quantities of stimulus than usual. This increase of action + constitutes the hot fit of fever, which is attended with various + increased secretions, with great concomitant heat, and general + uneasiness. The uneasiness attending this hot paroxysm of fever, or fit + of exertion, is very different from that, which attends the previous cold + fit, or fit of quiescence, and is frequently the cause of inflammation, + as in pleurisy, which is treated of in the next section.</p> + + <p>A similar effect occurs after the quiescence of our organs of sense; + those which are not subject to perpetual action, as the taste and smell, + are less liable to an exuberant accumulation of sensorial 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 quiescence.</p> + + <p>Where the previous quiescence has been owing to a defect of sensorial + power, and not to a defect of stimulus, as in the irritative fever with + weak pulse, a similar increase of activity of the arterial system + succeeds, either from the usual stimulus of the blood, or from a stimulus + less than usual; but as there is in general in these cases of fever with + weak pulse a deficiency of the quantity of the blood, the pulse in the + hot fit is weaker than in health, though it is stronger than in the cold + fit, as explained in No. <a href="#sect_XXXII_2">2</a>. of this section. + But at the same time in those fevers, where the defect of irritation is + owing to the defect of the quantity of sensorial power, as well as to the + defect of stimulus, another circumstance occurs; which consists in the + partial distribution of it, as appears in partial flushings, as of the + face or bosom, while the extremities are cold; and in the increase of + particular secretions, as of bile, saliva, insensible perspiration, with + great heat of the skin, or with partial sweats, or diarrhœa.</p> + + <p>There are also many uneasy sensations attending these increased + actions, which, like those belonging to the hot fit of fever with strong + pulse, are frequently followed by inflammation, as in scarlet fever; + which inflammation is nevertheless accompanied with a pulse weaker, + though quicker, than the pulse during the remission or intermission of + the paroxysms, though stronger than that of the previous cold fit.</p> + + <p>From hence I conclude, that both the cold and hot fits of fever are + necessary consequences of the perpetual and incessant action of the + arterial and glandular system; since those muscular fibres and those + organs of sense, which are most frequently exerted, become necessarily + most affected both with defect and accumulation of sensorial power: and + that hence <i>fever-fits are not an effort of nature to relieve + herself</i>, and that therefore they should always be prevented or + diminished as much as possible, by any means which decrease the general + or partial vascular actions, when they are greater, or by increasing them + when they are less than in health, as described in Sect. <a + href="#sect_XII_6_1">XII. 6. 1</a>.</p> + + <p>Thus have I endeavoured to explain, and I hope to the satisfaction of + the candid and patient reader, the principal symptoms or circumstances of + fever without the introduction of the supernatural power of spasm. To the + arguments in favour of the doctrine of spasm it may be sufficient to + reply, that in the evolution of medical as well as of dramatic + catastrophe,</p> + + <div class="poem"> + <div class="stanza"> + <p>Nec Deus intersit, nisi dignus vindice nodus inciderit.—H<font class="sc">OR</font>.</p> + </div> + </div> + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXXIII">XXXIII</a>.</h3> + +<p class="center" style="margin-top: 2em;">DISEASES OF SENSATION.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXXIII_1">I</a>. <a href="#sect_XXXIII_1_1">1</a>. + <i>Motions excited by sensation. Digestion. Generation. Pleasure of + existence. Hypochondriacism.</i> <a href="#sect_XXXIII_1_2">2</a>. + <i>Pain introduced. Sensitive fevers of two kinds.</i> <a + href="#sect_XXXIII_1_3">3</a>. <i>Two sensorial powers exerted in + sensitive fevers. Size of the blood. Nervous fevers distinguished from + putrid ones. The septic and antiseptic theory.</i> <a + href="#sect_XXXIII_1_4">4</a>. <i>Two kinds of delirium.</i> <a + href="#sect_XXXIII_1_5">5</a>. <i>Other animals are less liable to + delirium, cannot receive our contagious diseases, and are less liable to + madness.</i> <a href="#sect_XXXIII_2">II</a>. <a + href="#sect_XXXIII_2_1">1</a>. <i>Sensitive motions generated.</i> <a + href="#sect_XXXIII_2_2">2</a>. <i>Inflammation explained.</i> <a + href="#sect_XXXIII_2_3">3</a>. <i>Its remote causes from excess of + irritation, or of irritability, not from those pains which are owing to + defect of irritation. New vessels produced, and much heat.</i> <a + href="#sect_XXXIII_2_4">4</a>. <i>Purulent matter secreted.</i> <a + href="#sect_XXXIII_2_5">5</a>. <i>Contagion explained.</i> <a + href="#sect_XXXIII_2_6">6</a>. <i>Received but once.</i> <a + href="#sect_XXXIII_2_7">7</a>. <i>If common matter be contagious?</i> <a + href="#sect_XXXIII_2_8">8</a>. <i>Why some contagions are received but + once.</i> <a href="#sect_XXXIII_2_9">9</a>. <i>Why others may be received + frequently. Contagions of small-pox and measles do not act at the same + times. Two cases of such patients.</i> <a + href="#sect_XXXIII_2_10">10</a>. <i>The blood from patients in the + small-pox will not infect others. Cases of children thus inoculated. The + variolous contagion is not received into the blood. It acts by sensitive + association between the stomach and skin.</i> <a + href="#sect_XXXIII_3">III</a>. <a href="#sect_XXXIII_3_1">1</a>. + <i>Absorption of solids and fluids.</i> <a href="#sect_XXXIII_3_2">2</a>. + <i>Art of healing ulcers.</i> <a href="#sect_XXXIII_3_3">3</a>. + <i>Mortification attended with less pain in weak people.</i></p> + +</blockquote> + + <p><a name="sect_XXXIII_1">I</a>. <a name="sect_XXXIII_1_1">1</a>. As + many motions of the body are excited and continued by irritations, so + others require, either conjunctly with these, or separately, the + pleasurable or painful sensations, for the purpose of producing them with + due energy. Amongst these the business of digestion supplies us with an + instance: if the food, which we swallow, is not attended with agreeable + sensation, it digests less perfectly; and if very disagreeable sensation + accompanies it, such as a nauseous idea, or very disgustful taste, the + digestion becomes impeded; or retrograde motions of the stomach and + œsophagus succeed, and the food is ejected.</p> + + <p>The business of generation depends so much on agreeable sensation, + that, where the object is disgustful, neither voluntary exertion nor + irritation can effect the purpose; which is also liable to be interrupted + by the pain of fear or bashfulness.</p> + + <p>Besides the pleasure, which attends the irritations produced by the + objects of lust and hunger, there seems to be a sum of pleasurable + affection accompanying the various secretions of the numerous glands, + which constitute the pleasure of life, in contradistinction to the tedium + vitæ. This quantity or sum of pleasurable affection, seems to contribute + to the due or energetic performance of the whole moveable system, as well + that of the heart and arteries, as of digestion and of absorption; since + without the due quantity of pleasurable sensation, flatulency and + hypochondriacism affect the intestines, and a languor seizes the arterial + pulsations and secretions; as occurs in great and continued anxiety of + the mind.</p> + + <p><a name="sect_XXXIII_1_2">2</a>. Besides the febrile motions + occasioned by irritation, described in Sect. <a + href="#sect_XXXII">XXXII</a>. and termed irritative fever, it frequently + happens that pain is excited by the violence of the fibrous contractions; + and other new motions are then superadded, in consequence of sensation, + which we shall term febris sensitiva, or sensitive fever. It must be + observed, that most irritative fevers begin with a decreased exertion of + irritation, owing to defect of stimulus; but that on the contrary the + sensitive fevers, or inflammations, generally begin with the increased + exertion of sensation, as mentioned in Sect. <a + href="#sect_XXXI">XXXI</a>. on temperaments: for though the cold fit, + which introduces inflammation, commences with decreased irritation, yet + the inflammation itself commences in the hot fit during the increase of + sensation. Thus a common pustule, or phlegmon, in a part of little + sensibility does not excite an inflammatory fever; but if the stomach, + intestines, or the tender substance beneath the nails, be injured, great + sensation is produced, and the whole system is thrown into that kind of + exertion, which constitutes inflammation.</p> + + <p>These sensitive fevers, like the irritative ones, resolve themselves + into those with arterial strength, and those with arterial debility, that + is with excess or defect of sensorial power; these may be termed the + febris sensitiva pulsu forti, sensitive fever with strong pulse, which is + the synocha, or inflammatory fever; and the febris sensitiva pulsu + debili, sensitive fever with weak pulse, which is the typhus gravior, or + putrid fever of some writers.</p> + + <p><a name="sect_XXXIII_1_3">3</a>. The inflammatory fevers, which are + here termed sensitive fevers with strong pulse, are generally attended + with some topical inflammation, as pleurisy, peripneumony, or rheumatism, + which distinguishes them from irritative fevers with strong pulse. The + pulse is strong, quick, and full; for in this fever there is great + irritation, as well as great sensation, employed in moving the arterial + system. The size, or coagulable lymph, which appears on the blood, is + probably an increased secretion from the inflamed internal lining of the + whole arterial system, the thinner part being taken away by the increased + absorption of the inflamed lymphatics.</p> + + <p>The sensitive fevers with weak pulse, which are termed putrid or + malignant fevers, are distinguished from irritative fevers with weak + pulse, called nervous fevers, described in the last section, as the + former consist of inflammation joined with debility, and the latter of + debility alone. Hence there is greater heat and more florid colour of the + skin in the former, with petechiæ, or purple spots, and aphthæ, or + sloughs in the throat, and generally with previous contagion.</p> + + <p>When animal matter dies, as a slough in the throat, or the mortified + part of a carbuncle, if it be kept moist and warm, as during its abhesion + to a living body, it will soon putrify. This, and the origin of contagion + from putrid animal substances, seem to have given rise to the septic and + antiseptic theory of these fevers.</p> + + <p>The matter in pustules and ulcers is thus liable to become putrid, and + to produce microscopic animalcula; the urine, if too long retained, may + also gain a putrescent smell, as well as the alvine feces; but some + writers have gone so far as to believe, that the blood itself in these + fevers has smelt putrid, when drawn from the arm of the patient: but this + seems not well founded; since a single particle of putrid matter taken + into the blood can produce fever, how can we conceive that the whole mass + could continue a minute in a putrid state without destroying life? Add to + this, that putrid animal substances give up air, as in gangrenes; and + that hence if the blood was putrid, air should be given out, which in the + blood-vessels is known to occasion immediate death.</p> + + <p>In these sensitive fevers with strong pulse (or inflammations) there + are two sensorial faculties concerned in producing the disease, viz. + irritation and sensation; and hence, as their combined action is more + violent, the general quantity of sensorial power becomes further + exhausted during the exacerbation, and the system more rapidly weakened + than in irritative fever with strong pulse; where the spirit of animation + is weakened by but one mode of its exertion: so that this febris + sensitiva pulsu forti (or inflammatory fever,) may be considered as the + febris irritativa pulsu forti, with the addition of inflammation; and the + febris sensitiva pulsu debili (or malignant fever) may be considered as + the febris irritativa pulsu debili (or nervous fever), with the addition + of inflammation.</p> + + <p><a name="sect_XXXIII_1_4">4</a>. In these putrid or malignant fevers a + deficiency of irritability accompanies the increase of sensibility; and + by this waste of sensorial power by the excess of sensation, which was + already too small, arises the delirium and stupor which so perpetually + attend these inflammatory fevers with arterial debility. In these cases + the voluntary power first ceases to act from deficiency of sensorial + spirit; and the stimuli from external bodies have no effect on the + exhausted sensorial power, and a delirium like a dream is the + consequence. At length the internal stimuli cease to excite sufficient + irritation, and the secretions are either not produced at all, or too + parsimonious in quantity. Amongst these the secretion of the brain, or + production of the sensorial power, becomes deficient, till at last all + sensorial power ceases, except what is just necessary to perform the + vital motions, and a stupor succeeds; which is thus owing to the same + cause as the preceding delirium exerted in a greater degree.</p> + + <p>This kind of delirium is owing to a suspension of volition, and to the + disobedience of the senses to external stimuli, and is always occasioned + by great debility, or paucity of sensorial power; it is therefore a bad + sign at the end of inflammatory fevers, which had previous arterial + strength, as rheumatism, or pleurisy, as it shews the presence of great + exhaustion of sensorial power in a system, which having lately been + exposed to great excitement, is not so liable to be stimulated into its + healthy action, either by additional stimulus of food and medicines, or + by the accumulation of sensorial power during its present torpor. In + inflammatory fevers with debility, as those termed putrid fevers, + delirium is sometimes, as well as stupor, rather a favourable sign; as + less sensorial power is wasted during its continuance (see Class II. 1. + 6. 8.), and the constitution not having been previously exposed to excess + of stimulation, is more liable to be excited after previous + quiescence.</p> + + <p>When the sum of general pleasurable sensation becomes too great, + another kind of delirium supervenes, and the ideas thus excited are + mistaken for the irritations of external objects: such a delirium is + produced for a time by intoxicating drugs, as fermented liquors, or + opium: a permanent delirium of this kind is sometimes induced by the + pleasures of inordinate vanity, or by the enthusiastic hopes of heaven. + In these cases the power of volition is incapable of exertion, and in a + great degree the external senses become incapable of perceiving their + adapted stimuli, because the whole sensorial power is employed or + expended on the ideas excited by pleasurable sensation.</p> + + <p>This kind of delirium is distinguished from that which attends the + fevers above mentioned from its not being accompanied with general + debility, but simply with excess of pleasurable sensation; and is + therefore in some measure allied to madness or to reverie; it differs + from the delirium of dreams, as in this the power of volition is not + totally suspended, nor are the senses precluded from external + stimulation; there is therefore a degree of consistency, in this kind of + delirium, and a degree of attention to external objects, neither of which + exist in the delirium of fevers or in dreams.</p> + + <p><a name="sect_XXXIII_1_5">5</a>. It would appear, that the vascular + system of other animals are less liable to be put into action by their + general sum of pleasurable or painful sensation; and that the trains of + their ideas, and the muscular motions usually associated with them, are + less powerfully connected than in the human system. For other animals + neither weep, nor smile, nor laugh; and are hence seldom subject to + delirium, as treated of in Sect. <a href="#sect_XVI">XVI</a>. on + Instinct. Now as our epidemic and contagious diseases are probably + produced by disagreeable sensation, and not simply by irritation; there + appears a reason, why brute animals are less liable to epidemic or + contagious diseases; and secondly, why none of our contagions, as the + small-pox or measles, can be communicated to them, though one of theirs, + viz. the hydrophobia, as well as many of their poisons, as those of + snakes and of in insects, communicate their deleterious or painful + effects to mankind.</p> + + <p>Where the quantity of general painful sensation is too great in the + system, inordinate voluntary exertions are produced either of our ideas, + as in melancholy and madness, or of our muscles, as in convulsion. From + these maladies also brute animals are much more exempt than mankind, + owing to their greater inaptitude to voluntary exertion, as mentioned in + Sect. <a href="#sect_XVI">XVI</a>. on Instinct.</p> + + <p><a name="sect_XXXIII_2">II</a>. <a name="sect_XXXIII_2_1">1</a>. When + any moving organ is excited into such violent motions, that a quantity of + pleasurable or painful sensation is produced, it frequently happens (but + not always) that new motions of the affected organ are generated in + consequence of the pain or pleasure, which are termed inflammation.</p> + + <p>These new motions are of a peculiar kind, tending to distend the old, + and to produce new fibres, and thence to elongate the straight muscles, + which serve locomotion, and to form new vessels at the extremities or + sides of the vascular muscles.</p> + + <p><a name="sect_XXXIII_2_2">2</a>. Thus the pleasurable sensations + produce an enlargement of the nipples of nurses, of the papillæ of the + tongue, of the penis, and probably produce the growth of the body from + its embryon state to its maturity; whilst the new motions in consequence + of painful sensation, with the growth of the fibres or vessels, which + they occasion, are termed inflammation.</p> + + <p>Hence when the straight muscles are inflamed, part of their tendons at + each extremity gain new life and sensibility, and thus the muscle is for + a time elongated; and inflamed bones become soft, vascular, and sensible. + Thus new vessels shoot over the cornea of inflamed eyes, and into + scirrhous tumours, when they become inflamed; and hence all inflamed + parts grow together by intermixture, and inosculation of the new and old + vessels.</p> + + <p>The heat is occasioned from the increased secretions either of mucus, + or of the fibres, which produce or elongate the vessels. The red colour + is owing to the pellucidity of the newly formed vessels, and as the + arterial parts of them are probably formed before their correspondent + venous parts.</p> + + <p><a name="sect_XXXIII_2_3">3</a>. These new motions are excited either + from the increased quantity of sensation in consequence of greater + fibrous contractions, or from increased sensibility, that is, from the + increased quantity of sensorial power in the moving organ. Hence they are + induced by great external stimuli, as by wounds, broken bones; and by + acrid or infectious materials; or by common stimuli on those organs, + which have been some time quiescent; as the usual light of the day + inflames the eyes of those, who have been confined in dungeons; and the + warmth of a common fire inflames those, who have been previously exposed + to much cold.</p> + + <p>But these new motions are never generated by that pain, which arises + from defect of stimulus, as from hunger, thirst, cold, or inanition, with + all those pains, which are termed nervous. Where these pains exist, the + motions of the affected part are lessened; and if inflammation succeeds, + it is in some distant parts; as coughs are caused by coldness and + moisture being long applied to the feet; or it is in consequence of the + renewal of the stimulus, as of heat or food, which excites our organs + into stronger action after their temporary quiescence; as kibed heels + after walking in snow.</p> + + <p><a name="sect_XXXIII_2_4">4</a>. But when these new motions of the + vascular muscles are exerted with greater violence, and these vessels are + either elongated too much or too hastily, a new material is secreted from + their extremities, which is of various kinds according to the peculiar + animal motions of this new kind of gland, which secretes it; such is the + pus laudabile or common matter, the variolous matter, venereal matter, + catarrhous matter, and many others.</p> + + <p><a name="sect_XXXIII_2_5">5</a>. These matters are the product of an + animal process; they are secreted or produced from the blood by certain + diseased motions of the extremities of the blood-vessels, and are on that + account all of them contagious; for if a portion of any of these matters + is transmitted into the circulation, or perhaps only inserted into the + skin, or beneath the cuticle of an healthy person, its stimulus in a + certain time produces the same kind of morbid motions, by which itself + was produced; and hence a similar kind is generated. See Sect. <a + href="#sect_XXXIX_6_1">XXXIX. 6. 1</a>.</p> + + <p><a name="sect_XXXIII_2_6">6</a>. It is remarkable, that many of these + contagious matters are capable of producing a similar disease but once; + as the small-pox and measles; and I suppose this is true of all those + contagious diseases, which are spontaneously cured by nature in a certain + time; for if the body was capable of receiving the disease a second time, + the patient must perpetually infect himself by the very matter, which he + has himself produced, and is lodged about him; and hence he could never + become free from the disease. Something similar to this is seen in the + secondary fever of the confluent small-pox; there is a great absorption + of variolous matter, a very minute part of which would give the genuine + small-pox to another person; but here it only stimulates the system into + common fever; like that which common puss, or any other acrid material + might occasion.</p> + + <p><a name="sect_XXXIII_2_7">7</a>. In the pulmonary consumption, where + common matter is daily absorbed, an irritative fever only, without new + inflammation, is generally produced; which is terminated like other + irritative fevers by sweats, or loose stools. Hence it does not appear, + that this absorbed matter always acts as a contagious material producing + fresh inflammation or new abscesses. Though there is reason to believe, + that the first time any common matter is absorbed, it has this effect, + but not the second time, like the variolous matter above mentioned.</p> + + <p>This accounts for the opinion, that the pulmonary consumption is + sometimes infectious, which opinion was held by the ancients, and + continues in Italy at present; and I have myself seen three or four + instances, where a husband and wife, who have slept together, and have + thus much received each other's breath, who have infected each other, and + both died in consequence of the original taint of only one of them. This + also accounts for the abscesses in various parts of the body, that are + sometimes produced after the inoculated small-pox is terminated; for this + second absorption of variolous matter acts like common matter, and + produces only irritative fever in those children, whose constitutions + have already experienced the absorption of common matter; and + inflammation with a tendency to produce new abscesses in those, whose + constitutions have not experienced the absorptions of common matter.</p> + + <p>It is probable, that more certain proofs might have been found to + shew, that common matter is infectious the first time it is absorbed, + tending to produce similar abscesses, but not the second time of its + absorption, if this subject had been attended to.</p> + + <p><a name="sect_XXXIII_2_8">8</a>. These contagious diseases are very + numerous, as the plague, small-pox, chicken-pox, measles, scarlet-fever, + pemphigus, catarrh, chincough, venereal disease, itch, trichoma, tinea. + The infectious material does not seem to be dissolved by the air, but + only mixed with it perhaps in fine powder, which soon subsides; since + many of these contagions can only be received by actual contact; and + others of them only at small distances from the infected person; as is + evident from many persons having been near patients of the small-pox + without acquiring the disease.</p> + + <p>The reason, why many of these diseases are received but once, and + others repeatedly, is not well understood; it appears to me, that the + constitution becomes so accustomed to the stimuli of these infectious + materials, by having once experienced them, that though irritative + motions, as hectic fevers, may again be produced by them, yet no + sensation, and in consequence no general inflammation succeeds; as + disagreeable smells or tastes by habit cease to be perceived; they + continue indeed to excite irritative ideas on the organs of sense, but + these are not succeeded by sensation.</p> + + <p>There are many irritative motions, which were at first succeeded by + sensation, but which by frequent repetition cease to excite sensation, as + explained in Sect. <a href="#sect_XX">XX</a>. on Vertigo. And, that this + circumstance exists in respect to infectious matter appears from a known + fact; that nurses, who have had the small-pox, are liable to experience + small ulcers on their arms by the contact of variolous matter in lifting + their patients; and that when patients, who have formerly had the + small-pox have been inoculated in the arm, a phlegmon, or inflamed sore, + has succeeded, but no subsequent fever. Which shews, that the contagious + matter of the small-pox has not lost its power of stimulating the part it + is applied to, but that the general system is not affected in + consequence. See Section <a href="#sect_XII_7_6">XII. 7. 6</a>. <a + href="#sect_XIX_9">XIX. 9</a>.</p> + + <p><a name="sect_XXXIII_2_9">9</a>. From the accounts of the plague, + virulent catarrh, and putrid dysentery, it seems uncertain, whether these + diseases are experienced more than once; but the venereal disease and + itch are doubtless repeatedly infectious; and as these diseases are never + cured spontaneously, but require medicines, which act without apparent + operation, some have suspected, that the contagious material produces + similar matter rather by a chemical change of the fluids, than by an + animal process; and that the specific medicines destroy their virus by + chemically combining with it. This opinion is successfully combated by + Mr. Hunter, in his Treatise on Venereal Disease, Part I. c. i.</p> + + <p>But this opinion wants the support of analogy, as there is no known + process in animal bodies, which is purely chemical, not even digestion; + nor can any of these matters be produced by chemical processes. Add to + this, that it is probable, that the insects, observed in the pustules of + the itch, and in the stools of dysenteric patients, are the consequences, + and not the causes of these diseases. And that the specific medicines, + which cure the itch and lues venerea, as brimstone and mercury, act only + by increasing the absorption of the matter in the ulcuscles of those + diseases, and thence disposing them to heal; which would otherwise + continue to spread.</p> + + <p>Why the venereal disease, and itch, and tenia, or scald head, are + repeatedly contagious, while those contagions attended with fever can be + received but once, seems to depend on their being rather local diseases + than universal ones, and are hence not attended with fever, except the + purulent fever in their last stages, when the patient is destroyed by + them. On this account the whole of the system does not become habituated + to these morbid actions, so as to cease to be affected with sensation by + a repetition of the contagion. Thus the contagious matter of the venereal + disease, and of the tenia, affects the lymphatic glands, as the inquinal + glands, and those about the roots of the hair and neck, where it is + arrested, but does not seem to affect the blood-vessels, since no fever + ensues.</p> + + <p>Hence it would appear, that these kinds of contagion are propagated + not by means of the circulation, but by sympathy of distant parts with + each other; since if a distant part, as the palate, should be excited by + sensitive association into the same kind of motions, as the parts + originally affected by the contact of infectious matter; that distant + part will produce the same kind of infectious matter; for every secretion + from the blood is formed from it by the peculiar motions of the fine + extremities of the gland, which secretes it; the various secreted fluids, + as the bile, saliva, gastric juice, not previously existing, as such, in + the blood-vessels.</p> + + <p>And this peculiar sympathy between the genitals and the throat, owing + to sensitive association, appears not only in the production of venereal + ulcers in the throat, but in variety of other instances, as in the mumps, + in the hydrophobia, some coughs, strangulation, the production of the + beard, change of voice at puberty. Which are further described in Class + IV. 1. 2. 7.</p> + + <p>To evince that the production of such large quantities of contagious + matter, as are seen in some variolous patients, so as to cover the whole + skin almost with pustules, does not arise from any chemical fermentation + in the blood, but that it is owing to morbid motions of the fine + extremities of the capillaries, or glands, whether these be ruptured or + not, appears from the quantity of this matter always corresponding with + the quantity of the fever; that is, with the violent exertions of those + glands and capillaries, which are the terminations of the arterial + system.</p> + + <p>The truth of this theory is evinced further by a circumstance observed + by Mr. J. Hunter, in his Treatise on Venereal Disease; that in a patient, + who was inoculated for the small-pox, and who appeared afterwards to have + been previously infested with the measles, the progress of the small-pox + was delayed till the measles had run their course, and that then the + small-pox went through its usual periods.</p> + + <p>Two similar cases fell under my care, which I shall here relate, as it + confirms that of Mr. Hunter, and contributes to illustrate this part of + the theory of contagious diseases. I have transcribed the particulars + from a letter of Mr. Lightwood of Yoxal, the surgeon who daily attended + them, and at my request, after I had seen them, kept a kind of journal of + their cases.</p> + + <p>Miss H. and Miss L. two sisters, the one about four and the other + about three years old, were inoculated Feb. 7, 1791. On the 10th there + was a redness on both arms discernible by a glass. On the 11th their arms + were so much inflamed as to leave no doubt of the infection having taken + place. On the 12th less appearance of inflammation on their arms. In the + evening Miss L. had an eruption, which resembled the measles. On the 12th + the eruption on Miss L. was very full on the face and breast, like the + measles, with considerable fever. It was now known, that the measles were + in a farm house in the neighbourhood. Miss H.'s arm less inflamed than + yesterday. On the 14th Miss L.'s fever great, and the eruption universal. + The arm appears to be healed. Miss H.'s arm somewhat redder. They were + now put into separate rooms. On the 15th Miss L.'s arms as yesterday. + Eruption continues. Miss H.'s arms have varied but little. 16th, the + eruptions on Miss L. are dying away, her fever gone. Begins to have a + little redness in one arm at the place of inoculation. Miss H.'s arms get + redder, but she has no appearance of complaint. 20th, Miss L.'s arms have + advanced slowly till this day, and now a few pustules appear. Miss H.'s + arm has made little progress from the 16th to this day, and now she has + some fever. 21st, Miss L. as yesterday. Miss H. has much inflammation, + and an increase of the red circle on one arm to the size of half a crown, + and had much fever at night, with fetid breath. 22d, Miss L.'s pustules + continue advancing. Miss H.'s inflammation of her arm and red circle + increases. A few red spots appear in different parts with some degree of + fever this morning, 23d. Miss L. has a larger crop of pustules. Miss H. + has small pustules and great inflammation of her arms, with but one + pustule likely to suppurate. After this day they gradually got well, and + the pustules disappeared.</p> + + <p>In one of these cases the measles went through their common course + with milder symptoms than usual, and in the other the measly contagion + seemed just sufficient to stop the progress of variolous contagion, but + without itself throwing the constitution into any disorder. At the same + time both the measles and small-pox seem to have been rendered milder. + Does not this give an idea, that if they were both inoculated at the same + time, that neither of them might affect the patient?</p> + + <p>From these cases I contend, that the contagious matter of these + diseases does not affect the constitution by a fermentation, or chemical + change of the blood, because then they must have proceeded together, and + have produced a third something, not exactly similar to either of them: + but that they produce new motions of the cutaneous terminations of the + blood-vessels, which for a time proceed daily with increasing activity, + like some paroxysms of fever, till they at length secrete or form a + similar poison by these unnatural actions.</p> + + <p>Now as in the measles one kind of unnatural motion takes place, and in + the small-pox another kind, it is easy to conceive, that these different + kinds of morbid motions cannot exist together; and therefore, that that + which has first begun will continue till the system becomes habituated to + the stimulus which occasions it, and has ceased to be thrown into action + by it; and then the other kind of stimulus will in its turn produce + fever, and new kinds of motions peculiar to itself.</p> + + <p><a name="sect_XXXIII_2_10">10</a>. On further considering the action + of contagious matter, since the former part of this work was sent to the + press; where I have asserted, in Sect. <a href="#sect_XXII_3_3">XXII. 3. + 3</a>. that it is probable, that the variolous matter is diffused through + the blood; I prevailed on my friend Mr. Power, surgeon at Bosworth in + Leicestershire to try, whether the small-pox could be inoculated by using + the blood of a variolous patient instead of the matter from the pustules; + as I thought such an experiment might throw some light at least on this + interesting subject. The following is an extract from his + letter:—</p> + + <p>"March 11, 1793. I inoculated two children, who had not had the + small-pox, with blood; which was taken from a patient on the second day + after the eruption commenced, and before it was completed. And at the + same time I inoculated myself with blood from the same person, in order + to compare the appearances, which might arise in a person liable to + receive the infection, and in one not liable to receive it. On the same + day I inoculated four other children liable to receive the infection with + blood taken from another person on the fourth day after the commencement + of the eruption. The patients from whom the blood was taken had the + disease mildly, but had the most pustules of any I could select from + twenty inoculated patients; and as much of the blood was insinuated under + the cuticle as I could introduce by elevating the skin without drawing + blood; and three or four such punctures were made in each of their arms, + and the blood was used in its fluid state.</p> + + <p>"As the appearances in all these patients, as well as in myself, were + similar, I shall only mention them in general terms. March 13. A slight + subcuticular discoloration, with rather a livid appearance, without + soreness or pain, was visible in them all, as well as in my own hand. 15. + The discoloration somewhat less, without pain or soreness. Some patients + inoculated on the same day with variolous matter have considerable + inflammation. 17. The discoloration is quite gone in them all, and from + my own hand, a dry mark only remaining. And they were all inoculated on + the 18th, with variolous matter, which produced the disease in them + all."</p> + + <p>Mr. Power afterwards observes, that, as the patients from whom the + blood was taken had the disease mildly, it may be supposed, that though + the contagious matter might be mixed with the blood, it might still be in + too dilute a state to convey the infection; but adds at the same time, + that he has diluted recent matter with at least five times its quantity + of water, and which has still given the infection; though he has + sometimes diluted it so far as to fail.</p> + + <p>The following experiments were instituted at my request by my friend + Mr. Hadley, surgeon in Derby, to ascertain whether the blood of a person + in the small-pox be capable of communicating the disease. "Experiment + 1st. October 18th, 1793. I took some blood from a vein in the arm of a + person who had the small-pox, on the second day of the eruption, and + introduced a small quantity of it immediately with the point of a lancet + between the scars and true skin of the right arm of a boy nine years old + in two or three different places; the other arm was inoculated with + variolous matter at the same time.</p> + + <p>"19th. The punctured parts of the right arm were surrounded with some + degree of subcuticular inflammation. 20th. The inflammation more + considerable, with a slight degree of itching, but no pain upon pressure. + 21st. Upon examining the arm this day with a lens I found the + inflammation less extensive, and the redness changing to a deep yellow or + orange-colour, 22d. Inflammation nearly gone. 23d. Nothing remained, + except a slight discoloration and a little scurfy appearance on the + punctures. At the same time the inflammation of the arm inoculated with + variolous matter was increasing fast, and he had the disease mildly at + the usual time.</p> + + <p>"Experiment 2d. I inoculated another child at the same time and in the + same manner, with blood taken on the first day of the eruption; but as + the appearance and effects were similar to those in the preceding + experiment, I shall not relate them minutely.</p> + + <p>"Experiment 3d. October 20th. Blood was taken from a person who had + the small-pox, on the third day of the eruption, and on the sixth from + the commencement of the eruptive fever. I introduced some of it in its + fluid state into both arms of a boy seven years old.</p> + + <p>21st. There appeared to be some inflammation under the cuticle, where + the punctures were made. 22d. Inflammation more considerable. 23d. On + this day the inflammation was somewhat greater, and the cuticle rather + elevated.</p> + + <p>"24th. Inflammation much less, and only a brown or orange-colour + remained. 25th. Scarcely any discoloration left. On this day he was + inoculated with variolous matter, the progress of the infection went on + in the usual way, and he had the small-pox very favourably.</p> + + <p>"At this time I was requested to inoculate a young person, who was + thought to have had the small-pox, but his parents were not quite + certain; in one arm I introduced variolous matter, and in the other + blood, taken as in experiment 3d. On the second day after the operation, + the punctured parts were inflamed, though I think the arm in which I had + inserted variolous matter was rather more so than the other. On the third + the inflammation was increased, and looked much the same as in the + preceding experiment. 4th. The inflammation was much diminished, and on + the 5th almost gone. He was exposed at the same time to the natural + infection, but has continued perfectly well.</p> + + <p>"I have frequently observed (and believe most practitioners have done + the same), that if variolous matter be inserted in the arm of a person + who has previously had the small-pox, that the inflammation on the second + or third days is much greater, than if they had not had the disease, but + on the fourth or fifth it disappears.</p> + + <p>"On the 23d I introduced blood into the arms of three more children, + taken on the third and fourth days of the eruption. The appearances were + much the same as mentioned in experiments first and third. They were + afterwards inoculated with variolous matter, and had the disease in the + regular way.</p> + + <p>"The above experiments were made with blood taken from a small vein in + the hand or foot of three or four different patients, whom I had at that + time under inoculation. They were selected from 160, as having the + greatest number of pustules. The part was washed with warm water before + the blood was taken, to prevent the possibility of any matter being mixed + with it from the surface."</p> + + <p>Shall we conclude from hence, that the variolous matter never enters + the blood-vessels? but that the morbid motions of the vessels of the skin + around the insertion of it continue to increase in a larger and larger + circle for six or seven days; that then their quantity of morbid action + becomes great enough to produce a fever-fit, and to affect the stomach by + association of motions? and finally, that a second association of motions + is produced between the stomach and the other parts of the skin, inducing + them into morbid actions similar to those of the circle round the + insertion of the variolous matter? Many more experiments and observations + are required before this important question can be satisfactorily + answered.</p> + + <p>It may be adduced, that as the matter inserted into the skin of the + arm frequently swells the lymphatic in the axilla, that in that + circumstance it seems to be there arrested in its progress, and cannot be + imagined to enter the blood by that lymphatic gland till the swelling of + it subsides. Some other phænomena of the disease are more easily + reconcileable to this theory of sympathetic motions than to that of + absorption; as the time taken up between the insertion of the matter, and + the operation of it on the system, as mentioned above. For the circle + around the insertion is seen to increase, and to inflame; and I believe, + undergoes a kind of diurnal paroxysm of torpor and paleness with a + succeeding increase of action and colour, like a topical fever-fit. + Whereas if the matter is conceived to circulate for six or seven days + with the blood, without producing disorder, it ought to be rendered + milder, or the blood-vessels more familiarized to its acrimony.</p> + + <p>It is much easier to conceive from this doctrine of associated or + sympathetic motions of distant parts of the system, how it happens, that + the variolous infection can be received but once, as before explained; + than by supposing, that a change is effected in the mass of blood by any + kind of fermentative process.</p> + + <p>The curious circumstance of the two contagions of small-pox and + measles not acting at the same time, but one of them resting or + suspending its action till that of the other ceases, may be much easier + explained from sympathetic or associated actions of the infected part + with other parts of the system, than it can from supposing the two + contagions to enter the circulation.</p> + + <p>The skin of the face is subject to more frequent vicissitudes of heat + and cold, from its exposure to the open air, and is in consequence more + liable to sensitive association with the stomach than any other part of + the surface of the body, because their actions have been more frequently + thus associated. Thus in a surfeit from drinking cold water, when a + person is very hot and fatigued, an eruption is liable to appear on the + face in consequence of this sympathy. In the same manner the rosy + eruption on the faces of drunkards more probably arises from the sympathy + of the face with the stomach, rather than between the face and the liver, + as is generally supposed.</p> + + <p>This sympathy between the stomach and the skin of the face is apparent + in the eruption of the small-pox; since, where the disease is in + considerable quantity, the eruption on the face first succeeds the + sickness of the stomach. In the natural disease the stomach seems to be + frequently primarily affected, either alone or along with the tonsils, as + the matter seems to be only diffused in the air, and by being mixed with + the saliva, or mucus of the tonsils, to be swallowed into the + stomach.</p> + + <p>After some days the irritative circles of motions become disordered by + this new stimulus, which acts upon the mucus lining of the stomach; and + sickness, vertigo, and a diurnal fever succeed. These disordered + irritative motions become daily increased for two or three days, and then + by their increased action certain sensitive motions, or inflammation, is + produced, and at the next cold fit of fever, when the stomach recovers + from its torpor, an inflammation of the external skin is formed in points + (which afterwards suppurate), by sensitive association, in the same + manner as a cough is produced in consequence of exposing the feet to + cold, as described in Sect. <a href="#sect_XXV_17">XXV. 17</a>. and Class + IV. 2. I. 7. If the inoculated skin of the arm, as far as it appears + inflamed, was to be cut out, or destroyed by caustic, before the fever + commenced, as suppose on the fourth day after inoculation, would this + prevent the disease? as it is supposed to prevent the hydrophobia.</p> + + <p><a name="sect_XXXIII_3">III</a>. <a name="sect_XXXIII_3_1">1</a>. + Where the new vessels, and enlarged old ones, which constitute + inflammation, are not so hastily distended as to burst, and form a new + kind of gland for the secretion of matter, as above mentioned; if such + circumstances happen as diminish the painful sensation, the tendency to + growth ceases, and by and by an absorption commences, not only of the + superabundant quantity of fluids deposited in the inflamed part, but of + the solids likewise, and this even of the hardest kind.</p> + + <p>Thus during the growth of the second set of teeth in children, the + roots of the first set are totally absorbed, till at length nothing of + them remains but the crown; though a few weeks before, if they are drawn + immaturely, their roots are found complete. Similar to this Mr. Hunter + has observed, that where a dead piece of bone is to exfoliate, or to + separate from a living one, that the dead part does not putrify, but + remains perfectly sound, while the surface of the living part of the + bone, which is in contact with the dead part, becomes absorbed, and thus + effects its separation. Med. Comment. Edinb. V. 1. 425. In the same + manner the calcareous matter of gouty concretions, the coagulable lymph + deposited on inflamed membranes in rheumatism and extravasated blood + become absorbed; which are all as solid and as indissoluble materials as + the new vessels produced in inflammation.</p> + + <p>This absorption of the new vessels and deposited fluids of inflamed + parts is called resolution: it is produced by first using such internal + means as decrease the pain of the part, and in consequence its new + motions, as repeated bleeding, cathartics, diluent potations, and warm + bath.</p> + + <p>After the vessels are thus emptied, and the absorption of the new + vessels and deposited fluids is evidently begun, it is much promoted by + stimulating the part externally by solutions of lead, or other metals, + and internally by the bark, and small doses of opium. Hence when an + ophthalmy begins to become paler, any acrid eye-water, as a solution of + six grains of white vitriol in an ounce of water, hastens the absorption, + and clears the eye in a very short time. But the same application used a + few days sooner would have increased the inflammation. Hence after + evacuation opium in small doses may contribute to promote the absorption + of fluids deposited on the brain, as observed by Mr. Bromfield in his + treatise of surgery.</p> + + <p><a name="sect_XXXIII_3_2">2</a>. Where an abscess is formed by the + rupture of these new vessels, the violence of inflammation ceases, and a + new gland separates a material called pus: at the same time a less degree + of inflammation produces new vessels called vulgarly proud flesh; which, + if no bandage confines its growth, nor any other circumstance promotes + absorption in the wound, would rise to a great height above the usual + size of the part.</p> + + <p>Hence the art of healing ulcers consists in producing a tendency to + absorption in the wound greater than the deposition. Thus when an + ill-conditioned ulcer separates a copious and thin discharge, by the use + of any stimulus, as of salts of lead, or mercury, or copper externally + applied, the discharge becomes diminished in quantity, and becomes + thicker, as the thinner parts are first absorbed.</p> + + <p>But nothing so much contributes to increase the absorption in a wound + as covering the whole limb above the sore with a bandage, which should be + spread with some plaster, as with emplastrum de minio, to prevent it from + slipping. By this artificial tightness of the skin, the arterial + pulsations act with double their usual power in promoting the ascending + current of the fluid in the valvular lymphatics.</p> + + <p>Internally the absorption from ulcers should be promoted first by + evacuation, then by opium, bark, mercury, steel.</p> + + <p><a name="sect_XXXIII_3_3">3</a>. Where the inflammation proceeds with + greater violence or rapidity, that is, when by the painful sensation a + more inordinate activity of the organ is produced, and by this great + activity an additional quantity of painful sensation follows in an + increasing ratio, till the whole of the sensorial power, or spirit of + animation, in the part becomes exhausted, a mortification ensues, as in a + carbuncle, in inflammations of the bowels, in the extremities of old + people, or in the limbs of those who are brought near a fire after having + been much benumbed with cold. And from hence it appears, why weak people + are more subject to mortification than strong ones, and why in weak + persons less pain will produce mortification, namely, because the + sensorial power is sooner exhausted by any excess of activity. I remember + seeing a gentleman who had the preceding day travelled two stages in a + chaise with what he termed a bearable pain in his bowels; which when I + saw him had ceased rather suddenly, and without a passage through him; + his pulse was then weak, though not very quick; but as nothing which he + swallowed would continue in his stomach many minutes, I concluded that + the bowel was mortified; he died on the next day. It is usual for + patients sinking under the small-pox with mortified pustules, and with + purple spots intermixed, to complain of no pain, but to say they are + pretty well to the last moment.</p> + +<p class="center" style="margin-top: 2em;"><i>Recapitulation.</i></p> + + <p><a name="sect_XXXIII_4">IV</a>. When the motions of any part of the + system, in consequence of previous torpor, are performed with more energy + than in the irritative fevers, a disagreeable sensation is produced, and + new actions of some part of the system commence in consequence of this + sensation conjointly with the irritation: which motions constitute + inflammation. If the fever be attended with a strong pulse, as in + pleurisy, or rheumatism, it is termed synocha sensitiva, or sensitive + fever with strong pulse; which is usually termed inflammatory fever. If + it be attended with weak pulse, it is termed typhus sensitivus, or + sensitive fever with weak pulse, or typhus gravior, or putrid malignant + fever.</p> + + <p>The synocha sensitiva, or sensitive fever with strong pulse, is + generally attended with some topical inflammation, as in peripneumony, + hepatitis, and is accompanied with much coagulable lymph, or size; which + rises to the surface of the blood, when taken into a bason, as it cools; + and which is believed to be the increased mucous secretion from the coats + of the arteries, inspissated by a greater absorption of its aqueous and + saline part, and perhaps changed by its delay in the circulation.</p> + + <p>The typhus sensitivus, or sensitive fever with weak pulse, is + frequently attended with delirium, which is caused by the deficiency of + the quantity of sensorial power, and with variety of cutaneous + eruptions.</p> + + <p>Inflammation is caused by the pains occasioned by excess of action, + and not by those pains which are occasioned by defect of action. These + morbid actions, which are thus produced by two sensorial powers, viz. by + irritation and sensation, secrete new living fibres, which elongate the + old vessels, or form new ones, and at the same time much heat is evolved + from these combinations. By the rupture of these vessels, or by a new + construction of their apertures, purulent matters are secreted of various + kinds; which are infectious the first time they are applied to the skin + beneath the cuticle, or swallowed with the saliva into the stomach. This + contagion acts not by its being absorbed into the circulation, but by the + sympathies, or associated actions, between the part first stimulated by + the contagious matter and the other parts of the system. Thus in the + natural small-pox the contagion is swallowed with the saliva, and by its + stimulus inflames the stomach; this variolous inflammation of the stomach + increases every day, like the circle round the puncture of an inoculated + arm, till it becomes great enough to disorder the circles of irritative + and sensitive motions, and thus produces fever-fits, with sickness and + vomiting. Lastly, after the cold paroxysm, or fit of torpor, of the + stomach has increased for two or three successive days, an inflammation + of the skin commences in points; which generally first appear upon the + face, as the associated actions between the skin of the face and that of + the stomach have been more frequently exerted together than those of any + other parts of the external surface.</p> + + <p>Contagious matters, as those of the measles and small-pox, do not act + upon the system at the same time; but the progress of that which was last + received is delayed, till the action of the former infection ceases. All + kinds of matter, even that from common ulcers, are probably contagious + the first time they are inserted beneath the cuticle or swallowed into + the stomach; that is, as they were formed by certain morbid actions of + the extremities of the vessels, they have the power to excite similar + morbid actions in the extremities of other vessels, to which they are + applied; and these by sympathy, or associations of motion, excite similar + morbid actions in distant parts of the system, without entering the + circulation; and hence the blood of a patient in the small-pox will not + give that disease by inoculation to others.</p> + + <p>When the new fibres or vessels become again absorbed into the + circulation, the inflammation ceases; which is promoted, after sufficient + evacuations, by external stimulants and bandages: but where the action of + the vessels is very great, a mortification of the part is liable to + ensue, owing to the exhaustion of sensorial power; which however occurs + in weak people without much pain, and without very violent previous + inflammation; and, like partial paralysis, may be esteemed one mode of + natural death of old people, a part dying before the whole.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXXIV">XXXIV</a>.</h3> + +<p class="center" style="margin-top: 2em;">DISEASES OF VOLITION.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXXIV_1">I</a>. <a href="#sect_XXXIV_1_1">1</a>. + <i>Volition defined. Motions termed involuntary are caused by volition. + Desires opposed to each other. Deliberation. Ass between two hay-cocks. + Saliva swallowed against one's desire. Voluntary motions distinguished + from those associated with sensitive motions.</i> <a + href="#sect_XXXIV_1_2">2</a>. <i>Pains from excess, and from defect of + motion. No pain is felt during vehement voluntary exertion; as in cold + fits of ague, labour-pains, strangury, tenesmus, vomiting, restlessness + in fevers, convulsion of a wounded muscle.</i> <a + href="#sect_XXXIV_1_3">3</a>. <i>Of holding the breath and screaming in + pain; why swine and dogs cry out in pain, and not sheep and horses. Of + grinning and biting in pain; why mad animals bite others.</i> <a + href="#sect_XXXIV_1_4">4</a>. <i>Epileptic convulsions explained, why the + fits begin with quivering of the under jaw, biting the tongue, and + setting the teeth; why the convulsive motions are alternately relaxed. + The phenomenon of laughter explained. Why children cannot tickle + themselves. How some have died from immoderate laughter.</i> <a + href="#sect_XXXIV_1_5">5</a>. <i>Of cataleptic spasms, of the locked jaw, + of painful cramps.</i> <a href="#sect_XXXIV_1_6">6</a>. <i>Syncope + explained. Why no external objects are perceived in syncope.</i> <a + href="#sect_XXXIV_1_7">7</a>. <i>Of palsy and apoplexy from violent + exertions. Case of Mrs. Scot. From dancing, scating, swimming. Case of + Mr. Nairn. Why palsies are not always immediately preceded by violent + exertions. Palsy and epilepsy from diseased livers. Why the right arm + more frequently paralytic than the left. How paralytic limbs regain their + motions.</i> <a href="#sect_XXXIV_2">II</a>. <i>Diseases of the sensual + motions from excess or defect of voluntary exertion.</i> <a + href="#sect_XXXIV_2_1">1</a>. <i>Madness.</i> <a + href="#sect_XXXIV_2_2">2</a>. <i>Distinguished from delirium.</i> <a + href="#sect_XXXIV_2_3">3</a>. <i>Why mankind more liable to insanity than + brutes.</i> <a href="#sect_XXXIV_2_4">4</a>. <i>Suspicion. Want of shame, + and of cleanliness.</i> <a href="#sect_XXXIV_2_5">5</a>. <i>They bear + cold, hunger, and fatigue. Charles XII. of Sweden.</i> <a + href="#sect_XXXIV_2_6">6</a>. <i>Pleasureable delirium, and insanity. + Child riding on a stick. Pains of martyrdom not felt.</i> <a + href="#sect_XXXIV_2_7">7</a>. <i>Dropsy.</i> <a + href="#sect_XXXIV_2_8">8</a>. <i>Inflammation cured by insanity.</i> <a + href="#sect_XXXIV_3">III</a>. <a href="#sect_XXXIV_3_1">1</a>. <i>Pain + relieved by reverie. Reverie is an exertion of voluntary and sensitive + motions.</i> <a href="#sect_XXXIV_3_2">2</a>. <i>Case of reverie.</i> <a + href="#sect_XXXIV_3_3">3</a>. <i>Lady supposed to have two souls.</i> <a + href="#sect_XXXIV_3_4">4</a>. <i>Methods of relieving pain.</i></p> + +</blockquote> + + <p><a name="sect_XXXIV_1">I</a>. <a name="sect_XXXIV_1_1">1</a>. Before + we commence this Section on Diseased Voluntary Motions, it may be + necessary to premise, that the word volition is not used in this work + exactly in its common acceptation. Volition is said in Section <a + href="#sect_V">V</a>. to bear the same analogy to desire and aversion, + which sensation does to pleasure and pain. And hence that, when desire or + aversion produces any action of the muscular fibres, or of the organs of + sense, they are termed volition; and the actions produced in consequence + are termed voluntary actions. Whence it appears, that motions of our + muscles or ideas may be produced in consequence of desire or aversion + without our having the power to prevent them, and yet these motions may + be termed voluntary, according to our definition of the word; though in + common language they would be called involuntary.</p> + + <p>The objects of desire and aversion are generally at a distance, + whereas those of pleasure and pain are immediately acting upon our + organs. Hence, before desire or aversion are exerted, so as to cause any + actions, there is generally time for deliberation; which consists in + discovering the means to obtain the object of desire, or to avoid the + object of aversion; or in examining the good or bad consequences, which + may result from them. In this case it is evident, that we have a power to + delay the proposed action, or to perform it; and this power of choosing, + whether we shall act or not, is in common language expressed by the word + volition, or will. Whereas in this work the word volition means simply + the active state of the sensorial faculty in producing motion in + consequence of desire or aversion: whether we have the power of + restraining that action, or not; that is, whether we exert any actions in + consequence of opposite desires or aversions, or not.</p> + + <p>For if the objects of desire or aversion are present, there is no + necessity to investigate or compare the <i>means</i> of obtaining them, + nor do we always deliberate about their consequences; that is, no + deliberation necessarily intervenes, and in consequence the power of + choosing to act or not is not exerted. It is probable, that this twofold + use of the word volition in all languages has confounded the + metaphysicians, who have disputed about free will and necessity. Whereas + from the above analysis it would appear, that during our sleep, we use no + voluntary exertions at all; and in our waking hours, that they are the + consequence of desire or aversion.</p> + + <p>To will is to act in consequence of desire; but to desire means to + desire something, even if that something be only to become free from the + pain, which causes the desire; for to desire nothing is not to desire; + the word desire, therefore, includes both the action and the object or + motive; for the object and motive of desire are the same thing. Hence to + desire without an object, that is, without a motive, is a solecism in + language. As if one should ask, if you could eat without food, or breathe + without air.</p> + + <p>From this account of volition it appears, that convulsions of the + muscles, as in epileptic fits, may in the common sense of that word be + termed involuntary; because no deliberation is interposed between the + desire or aversion and the consequent action; but in the sense of the + word, as above defined, they belong to the class of voluntary motions, as + delivered in Vol. II. Class III. If this use of the word be discordant to + the ear of the reader, the term morbid voluntary motions, or motions in + consequence of aversion, may be substituted in its stead.</p> + + <p>If a person has a desire to be cured of the ague, and has at the same + time an aversion (or contrary desire) to swallowing an ounce of Peruvian + bark; he balances desire against desire, or aversion against aversion; + and thus he acquires the power of choosing, which is the common + acceptation of the word <i>willing</i>. But in the cold fit of ague, + after having discovered that the act of shuddering, or exerting the + subcutaneous muscles, relieves the pain of cold; he immediately exerts + this act of volition, and shudders, as soon as the pain and consequent + aversion return, without any deliberation intervening; yet is this act, + as well as that of swallowing an ounce of the bark, caused by volition; + and that even though he endeavours in vain to prevent it by a weaker + contrary volition. This recalls to our minds the story of the hungry ass + between two hay-stacks, where the two desires are supposed so exactly to + counteract each other, that he goes to neither of the stacks, but + perishes by want. Now as two equal and opposite desires are thus supposed + to balance each other, and prevent all action, it follows, that if one of + these hay-stacks was suddenly removed, that the ass would irresistibly be + hurried to the other, which in the common use of the word might be called + an involuntary act; but which, in our acceptation of it, would be classed + amongst voluntary actions, as above explained.</p> + + <p>Hence to deliberate is to compare opposing desires or aversions, and + that which is the most interesting at length prevails, and produces + action. Similar to this, where two pains oppose each other, the stronger + or more interesting one produces action; as in pleurisy the pain from + suffocation would produce expansion of the lungs, but the pain occasioned + by extending the inflamed membrane, which lines the chest, opposes this + expansion, and one or the other alternately prevails.</p> + + <p>When any one moves his hand quickly near another person's eyes, the + eye-lids instantly close; this act in common language is termed + involuntary, as we have not time to deliberate or to exert any contrary + desire or aversion, but in this work it would be termed a voluntary act, + because it is caused by the faculty of volition, and after a few trials + the nictitation can be prevented by a contrary or opposing volition.</p> + + <p>The power of opposing volitions is best exemplified in the story of + Mutius Scævola, who is said to have thrust his hand into the fire before + Porcenna, and to have suffered it to be consumed for having failed him in + his attempt on the life of that general. Here the aversion for the loss + of same, or the unsatisfied desire to serve his country, the two + prevalent enthusiasms at that time, were more powerful than the desire of + withdrawing his hand, which must be occasioned by the pain of combustion; + of these opposing volitions</p> + + <div class="poem"> + <div class="stanza"> + <p>Vincit amor patriæ, laudumque immensa cupido.</p> + </div> + </div> + <p>If any one is told not to swallow his saliva for a minute, he soon + swallows it contrary to his will, in the common sense of that word; but + this also is a voluntary action, as it is performed by the faculty of + volition, and is thus to be understood. When the power of volition is + exerted on any of our senses, they become more acute, as in our attempts + to hear small noises in the night. As explained in Section <a + href="#sect_XIX_6">XIX. 6</a>. Hence by our attention to the fauces from + our desire not to swallow our saliva; the fauces become more sensible; + and the stimulus of the saliva is followed by greater sensation, and + consequent desire of swallowing it. So that the desire or volition in + consequence of the increased sensation of the saliva is more powerful, + than the previous desire not to swallow it. See Vol. II. Deglutitio + invita. In the same manner if a modest man wishes not to want to make + water, when he is confined with ladies in a coach or an assembly-room; + that very act of volition induces the circumstance, which he wishes to + avoid, as above explained; insomuch that I once saw a partial insanity, + which might be called a voluntary diabetes, which was occasioned by the + fear (and consequent aversion) of not being able to make water at + all.</p> + + <p>It is further necessary to observe here, to prevent any confusion of + voluntary, with sensitive, or associate motions, that in all the + instances of violent efforts to relieve pain, those efforts are at first + voluntary exertions; but after they have been frequently repeated for the + purpose of relieving certain pains, they become associated with those + pains, and cease at those times to be subservient to the will; as in + coughing, sneezing, and strangury. Of these motions those which + contribute to remove or dislodge the offending cause, as the actions of + the abdominal muscles in parturition or in vomiting, though they were + originally excited by volition, are in this work termed sensitive + motions; but those actions of the muscles or organs of sense, which do + not contribute to remove the offending cause, as in general convulsions + or in madness, are in this work termed voluntary motions, or motions in + consequence of aversion, though in common language they are called + involuntary ones. Those sensitive unrestrainable actions, which + contribute to remove the cause of pain are uniformly and invariably + exerted, as in coughing or sneezing; but those motions which are exerted + in consequence of aversion without contributing to remove the painful + cause, but only to prevent the sensation of it, as in epileptic, or + cataleptic fits, are not uniformly and invariably exerted, but change + from one set of muscles to another, as will be further explained; and may + by this criterion also be distinguished from the former.</p> + + <p>At the same time those motions, which are excited by perpetual + stimulus, or by association with each other, or immediately by + pleasureable or painful sensation, may properly be termed involuntary + motions, as those of the heart and arteries; as the faculty of volition + seldom affects those, except when it exists in unnatural quantity, as in + maniacal people.</p> + + <p><a name="sect_XXXIV_1_2">2</a>. It was observed in Section <a + href="#sect_XIV">XIV</a>. on the Production of Ideas, that those parts of + the system, which are usually termed the organs of sense, are liable to + be excited into pain by the excess of the stimulus of those objects, + which are by nature adapted to affect them; as of too great light, sound, + or pressure. But that these organs receive no pain from the defect or + absence of these stimuli, as in darkness or silence. But that our other + organs of perception, which have generally been called appetites, as of + hunger, thirst, want of heat, want of fresh air, are liable to be + affected with pain by the defect, as well as by the excess of their + appropriated stimuli.</p> + + <p>This excess or defect of stimulus is however to be considered only as + the remote cause of the pain, the immediate cause being the excess or + defect of the natural action of the affected part, according to Sect. <a + href="#sect_IV_5">IV. 5</a>. Hence all the pains of the body may be + divided into those from excess of motion, and those from defect of + motion; which distinction is of great importance in the knowledge and the + cure of many diseases. For as the pains from excess of motion either + gradually subside, or are in general succeeded by inflammation; so those + from defect of motion either gradually subside, or are in general + succeeded by convulsion, or madness. These pains are easily + distinguishable from each other by this circumstance, that the former are + attended with heat of the pained part, or of the whole body; whereas the + latter exists without increase of heat in the pained part, and is + generally attended with coldness of the extremities of the body; which is + the true criterion of what have been called nervous pains.</p> + + <p>Thus when any acrid material, as snuff or lime, falls into the eye, + pain and inflammation and heat are produced from the excess of stimulus; + but violent hunger, hemicrania, or the clavus hystericus, are attended + with coldness of the extremities, and defect of circulation. When we are + exposed to great cold, the pain we experience from the deficiency of heat + is attended with a quiescence of the motions of the vascular system; so + that no inflammation is produced, but a great desire of heat, and a + tremulous motion of the subcutaneous muscles, which is properly a + convulsion in consequence of this pain from defect of the stimulus of + heat.</p> + + <p>It was before mentioned, that as sensation consists in certain + movements of the sensorium, beginning at some of the extremities of it, + and propagated to the central parts of it; so volition consists of + certain other movements of the sensorium, commencing in the central parts + of it, and propagated to some of its extremities. This idea of these two + great powers of motion in the animal machine is confirmed from observing, + that they never exist in a great degree or universally at the same time; + for while we strongly exert our voluntary motions, we cease to feel the + pains or uneasinesses, which occasioned us to exert them.</p> + + <p>Hence during the time of fighting with fists or swords no pain is felt + by the combatants, till they cease to exert themselves. Thus in the + beginning of ague-fits the painful sensation of cold is diminished, while + the patient exerts himself in the shivering and gnashing of his teeth. He + then ceases to exert himself, and the pain of cold returns; and he is + thus perpetually induced to reiterate these exertions, from which he + experiences a temporary relief. The same occurs in labour-pains, the + exertion of the parturient woman relieves the violence of the pains for a + time, which recur again soon after she has ceased to use those exertions. + The same is true in many other painful diseases, as in the strangury, + tenesmus, and the efforts of vomiting; all these disagreeable sensations + are diminished or removed for a time by the various exertions they + occasion, and recur alternately with those exertions.</p> + + <p>The restlessness in some fevers is an almost perpetual exertion of + this kind, excited to relieve some disagreeable sensations; the + reciprocal opposite exertions of a wounded worm, the alternate + emprosthotonos and opisthotonos of some spasmodic diseases, and the + intervals of all convulsions, from whatever cause, seem to be owing to + this circumstance of the laws of animation; that great or universal + exertion cannot exist at the same time with great or universal sensation, + though they can exist reciprocally; which is probably resolvable into the + more general law, that the whole sensorial power being expended in one + mode of exertion, there is none to spare for any other. Whence syncope, + or temporary apoplexy, succeeds to epileptic convulsions.</p> + + <p><a name="sect_XXXIV_1_3">3</a>. Hence when any violent pain afflicts + us, of which we can neither avoid nor remove the cause, we soon learn to + endeavour to alleviate it, by exerting some violent voluntary effort, as + mentioned above; and are naturally induced to use those muscles for this + purpose, which have been in the early periods of our lives most + frequently or most powerfully exerted.</p> + + <p>Now the first muscles, which infants use most frequently, are those of + respiration; and on this account we gain a habit of holding our breath, + at the same time that we use great efforts to exclude it, for this + purpose of alleviating unavoidable pain; or we press out our breath + through a small aperture of the larynx, and scream violently, when the + pain is greater than is relievable by the former mode of exertion. Thus + children scream to relieve any pain either of body or mind, as from + anger, or fear of being beaten.</p> + + <p>Hence it is curious to observe, that those animals, who have more + frequently exerted their muscles of respiration violently, as in talking, + barking, or grunting, as children, dogs, hogs, scream much more, when + they are in pain, than those other animals, who use little or no language + in their common modes of life; as horses, sheep, and cows.</p> + + <p>The next most frequent or most powerful efforts, which infants are + first tempted to produce, are those with the muscles in biting hard + substances; indeed the exertion of these muscles is very powerful in + common mastication, as appears from the pain we receive, if a bit of bone + is unexpectedly found amongst our softer food; and further appears from + their acting to so great mechanical disadvantage, particularly when we + bite with the incisores, or canine teeth; which are first formed, and + thence are first used to violent exertion.</p> + + <p>Hence when a person is in great pain, the cause of which he cannot + remove, he sets his teeth firmly together, or bites some substance + 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 said to be + attended with "gnashing of teeth."</p> + + <p>Hence in violent spasmodic pains I have seen people bite not only + their tongues, but their arms or fingers, or those of the attendants, or + any object which was near them; and also strike, pinch, or tear, others + or themselves, particularly the part of their own body, which is painful + at the time. Soldiers, who die of painful wounds in battle, are said in + Homer to bite the ground. Thus also in the bellon, or colica saturnina, + the patients are said to bite their own flesh, and dogs in this disease + 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, is + owing to the same cause.</p> + + <p><a name="sect_XXXIV_1_4">4</a>. If the efforts of our voluntary + motions are exerted with still greater energy for the relief of some + disagreeable sensation, convulsions are produced; as the various kinds of + epilepsy, and in some hysteric paroxysms. In all these diseases a pain, + or disagreeable sensation is produced, frequently by worms, or acidity in + the bowels, or by a diseased nerve in the side, or head, or by the pain + of a diseased liver.</p> + + <p>In some constitutions a more intolerable degree of pain is produced in + some part at a distance from the cause by sensitive association, as + before explained; these pains in such constitutions arise to so great a + degree, that I verily believe no artificial tortures could equal some, + which I have witnessed; and am confident life would not have long been + preserved, unless they had been soon diminished or removed by the + universal convulsion of the voluntary motions, or by temporary + madness.</p> + + <p>In some of the unfortunate patients I have observed, the pain has + risen to an inexpressible degree, as above described, before the + convulsions have supervened; and which were preceded by screaming, and + grinning; in others, as in the common epilepsy, the convulsion has + immediately succeeded the commencement of the disagreeable sensations; + and as a stupor frequently succeeds the convulsions, they only seemed to + remember that a pain at the stomach preceded the fit, or some other + uneasy feel; or more frequently retained no memory at all of the + immediate cause of the paroxysm. But even in this kind of epilepsy, where + the patient does not recollect any preceding pain, the paroxysms + generally are preceded by a quivering motion of the under jaw, with a + biting of the tongue; the teeth afterwards become pressed together with + vehemence, and the eyes are then convulsed, before the commencement of + the universal convulsion; which are all efforts to relieve pain.</p> + + <p>The reason why these convulsive motions are alternately exerted and + remitted was mentioned above, and in Sect. <a href="#sect_XII_1_3">XII. + 1. 3</a>. when the exertions are such as give a temporary relief to the + pain, which excites them, they cease for a time, till the pain is again + perceived; and then new exertions are produced for its relief. We see + daily examples of this in the loud reiterated laughter of some people; + the pleasureable sensation, which excites this laughter, arises for a + time so high as to change its name and become painful: the convulsive + motions of the respiratory muscles relieve the pain for a time; we are, + however, unwilling to lose the pleasure, and presently put a stop to this + exertion, and immediately the pleasure recurs, and again as instantly + rises into pain. All of us have felt the pain of immoderate laughter; + children have been tickled into convulsions of the whole body; and others + have died in the act of laughing; probably from a paralysis succeeding + the long continued actions of the muscles of respiration.</p> + + <p>Hence we learn the reason, why children, who are so easily excited to + laugh by the tickling of other people's fingers, cannot tickle themselves + into laughter. The exertion of their hands in the endeavour to tickle + themselves prevents the necessity of any exertion of the respiratory + muscles to relieve the excess of pleasurable affection. See Sect. <a + href="#sect_XVII_3_5">XVII. 3. 5</a>.</p> + + <p>Chrysippus is recorded to have died laughing, when an ass was invited + to sup with him. The same is related of one of the popes, who, when he + was ill, saw a tame monkey at his bedside put on the holy thiara. Hall. + Phys. T. III. p. 306.</p> + + <p>There are instances of epilepsy being produced by laughing recorded by + Van Swieten, T. III. 402 and 308. And it is well known, that many people + have died instantaneously from the painful excess of joy, which probably + might have been prevented by the exertions of laughter.</p> + + <p>Every combination of ideas, which we attend to, occasions pain or + pleasure; those which occasion pleasure, furnish either social or selfish + pleasure, either malicious or friendly, or lascivious, or sublime + pleasure; that is, they give us pleasure mixed with other emotions, or + they give us unmixed pleasure, without occasioning any other emotions or + exertions at the same time. This unmixed pleasure, if it be great, + becomes painful, like all other animal motions from stimuli of every + kind; and if no other exertions are occasioned at the same time, we use + the exertion of laughter to relieve this pain. Hence laughter is + occasioned by such wit as excites simple pleasure without any other + emotion, such as pity, love, reverence. For sublime ideas are mixed with + admiration, beautiful ones with love, new ones with surprise; and these + exertions of our ideas prevent the action of laughter from being + necessary to relieve the painful pleasure above described. Whence + laughable wit consists of frivolous ideas, without connections of any + consequence, such as puns on words, or on phrases, incongruous junctions + of ideas; on which account laughter is so frequent in children.</p> + + <p>Unmixed pleasure less than that, which causes laughter, causes sleep, + as in singing children to sleep, or in slight intoxication from wine or + food. See Sect. <a href="#sect_XVIII_12">XVIII. 12</a>.</p> + + <p><a name="sect_XXXIV_1_5">5</a>. If the pains, or disagreeable + sensations, above described do not obtain a temporary relief from these + convulsive exertions of the muscles, those convulsive exertions continue + without remission, and one kind of catalepsy is produced. Thus when a + nerve or tendon produces great pain by its being inflamed or wounded, the + patient sets his teeth firmly together, and grins violently, to diminish + the pain; and if the pain is not relieved by this exertion, no relaxation + of the maxillary muscles takes place, as in the convulsions above + described, but the jaws remain firmly fixed together. This locked jaw is + the most frequent instance of cataleptic spasm, because we are more + inclined to exert the muscles subservient to mastication from their early + obedience to violent efforts of volition.</p> + + <p>But in the case related in Sect. <a href="#sect_XIX">XIX</a>. on + Reverie, the cataleptic lady had pain in her upper teeth; and pressing + one of her hands vehemently against her cheek-bone to diminish this pain, + it remained in that attitude for about half an hour twice a day, till the + painful paroxysm was over.</p> + + <p>I have this very day seen a young lady in this disease, (with which + she has frequently been afflicted,) she began to-day with violent pain + shooting from one side of the forehead to the occiput, and after various + struggles lay on the bed with her fingers and wrists bent and stiff for + about two hours; in other respects she seemed in a syncope with a natural + pulse. She then had intervals of pain and of spasm, and took three grains + of opium every hour till she had taken nine grains, before the pains and + spasm ceased.</p> + + <p>There is, however, another species of fixed spasm, which differs from + the former, as the pain exists in the contracted muscle, and would seem + rather to be the consequence than the cause of the contraction, as in the + cramp in the calf of the leg, and in many other parts of the body.</p> + + <p>In these spasms it should seem, that the muscle itself is first thrown + into contraction by some disagreeable sensation, as of cold; and that + then the violent pain is produced by the great contraction of the + muscular fibres extending its own tendons, which are said to be sensible + to extension only; and is further explained in Sect. <a + href="#sect_XVIII_15">XVIII. 15</a>.</p> + + <p><a name="sect_XXXIV_1_6">6</a>. Many instances have been given in this + work, where after violent motions excited by irritation, the organ has + become quiescent to less, and even to the great irritation, which induced + it into violent motion; as after looking long at the sun or any bright + colour, they cease to be seen; and after removing from bright day-light + into a gloomy room, the eye cannot at first perceive the objects, which + stimulate it less. Similar to this is the syncope, which succeeds after + the violent exertions of our voluntary motions, as after epileptic fits, + for the power of volition acts in this case as the stimulus in the other. + This syncope is a temporary palsy, or apoplexy, which ceases after a + time, the muscles recovering their power of being excited into action by + the efforts of volition; as the eye in the circumstance above mentioned + recovers in a little time its power of seeing objects in a gloomy room; + which were invisible immediately after coming out of a stronger light. + This is owing to an accumulation of sensorial power during the inaction + of those fibres, which were before accustomed to perpetual exertions, as + explained in Sect. <a href="#sect_XII_7_1">XII. 7. 1</a>. A slighter + degree of this disease is experienced by every one after great fatigue, + when the muscles gain such inability to further action, that we are + obliged to rest them for a while, or to summon a greater power of + volition to continue their motions.</p> + + <p>In all the syncopes, which I have seen induced after convulsive fits, + the pulse has continued natural, though the organs of sense, as well as + the locomotive muscles, have ceased to perform their functions; for it is + necessary for the perception of objects, that the external organs of + sense should be properly excited by the voluntary power, as the eye-lids + must be open, and perhaps the muscles of the eye put into action to + distend, and thence give greater pellucidity to the cornea, which in + syncope, as in death, appears flat and less transparent.</p> + + <p>The tympanum of the ear also seems to require a voluntary exertion of + its muscles, to gain its due tension, and it is probable the other + external organs of sense require a similar voluntary exertion to adapt + them to the distinct perception of objects. Hence in syncope as in sleep, + as the power of volition is suspended, no external objects are perceived. + See Sect. <a href="#sect_XVIII_5">XVIII. 5</a>. During the time which the + patient lies in a fainting fit, the spirit of animation becomes + accumulated; and hence the muscles in a while become irritable by their + usual stimulation, and the fainting fit ceases. See Sect. <a + href="#sect_XII_7_1">XII. 7. 1</a>.</p> + + <p><a name="sect_XXXIV_1_7">7</a>. If the exertion of the voluntary + motions has been still more energetic, the quiescence, which succeeds, is + so complete, that they cannot again be excited into action by the efforts + of the will. In this manner the palsy, and apoplexy (which is an + universal palsy) are frequently produced after convulsions, or other + violent exertions; of this I shall add a few instances.</p> + + <p>Platernus mentions some, who have died apoplectic from violent + exertions in dancing; and Dr. Mead, in his Essay on Poisons, records a + patient in the hydrophobia, who at one effort broke the cords which bound + him, and at the same instant expired. And it is probable, that those, who + have expired from immoderate laughter, have died from this paralysis + consequent to violent exertion. Mrs. Scott of Stafford was walking in her + garden in perfect health with her neighbour Mrs. ——; the + latter accidentally fell into a muddy rivulet, and tried in vain to + disengage herself by the assistance of Mrs. Scott's hand. Mrs. Scott + exerted her utmost power for many minutes, first to assist her friend, + and next to prevent herself from being pulled into the morass, as her + distressed companion would not disengage her hand. After other assistance + was procured by their united screams, Mrs. Scott walked to a chair about + twenty yards from the brook, and was seized with an apoplectic stroke: + which continued many days, and terminated in a total loss of her right + arm, and her speech; neither of which she ever after perfectly + recovered.</p> + + <p>It is said, that many people in Holland have died after skating too + long or too violently on their frozen canals; it is probable the death of + these, and of others, who have died suddenly in swimming, has been owing + to this great quiescence or paralysis; which has succeeded very violent + exertions, added to the concomitant cold, which has had greater effect + after the sufferers had been heated and exhausted by previous + exercise.</p> + + <p>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 cousin and fellow-student + of the same name, knowing the other could not swim, plunged into the + water after him, caught him by his clothes, and approaching the bank by a + vehement exertion propelled him safe to the land, but that instant, + seized, as was supposed, by the cramp, or paralysis, sunk to rise no + more. The reason why the cramp of the muscles, which compose the calf of + the leg, is so liable to affect swimmers, is, because these muscles have + very weak antagonists, 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 resistance of the water in swimming. See + Section <a href="#sect_XVIII_15">XVIII. 15</a>.</p> + + <p>It does not follow that every apoplectic or paralytic attack is + immediately preceded by vehement exertion; the quiescence, which succeeds + exertion, and which is not so great as to be termed paralysis, frequently + recurs afterwards at certain periods; and by other causes of quiescence, + occurring with those periods, as was explained in treating of the + paroxysms of intermitting fevers; the quiescence at length, becomes so + great as to be incapable of again being removed by the efforts of + volition, and complete paralysis is formed. See Section <a + href="#sect_XXXII_3_2">XXXII. 3. 2</a>.</p> + + <p>Many of the paralytic patients, whom I have seen, have evidently had + diseased livers from the too frequent potation of spirituous liquors; + some of them have had the gutta rosea on their faces and breasts; which + has in some degree receded either spontaneously, or by the use of + external remedies, and the paralytic stroke has succeeded; and as in + several persons, who have drank much vinous spirits, I have observed + epileptic fits to commence at about forty or fifty years of age, without + any hereditary taint, from the stimulus, as I believed, of a diseased + liver; I was induced to ascribe many paralytic cases to the same source; + which were not evidently the effect of age, or of unacquired debility. + And the account given before of dropsies, which very frequently are owing + to a paralysis of the absorbent system, and are generally attendant on + free drinkers of spirituous liquors, confirmed me in this opinion.</p> + + <p>The disagreeable irritation of a diseased liver produces exertions and + consequent quiescence; these by the accidental concurrence of other + causes of quiescence, as cold, solar or lunar periods, inanition, the + want of their usual portion of spirit of wine, at length produces + paralysis.</p> + + <p>This is further confirmed by observing, that the muscles, we most + frequently, or most powerfully exert, are most liable to palsy; as those + of the voice and of articulation, and of those paralytics which I have + seen, a much greater proportion have lost the use of their right arm; + which is so much more generally exerted than the left.</p> + + <p>I cannot dismiss this subject without observing, that after a + paralytic stroke, if the vital powers are not much injured, that the + patient has all the movements of the affected limb to learn over again, + just as in early infancy; the limb is first moved by the irritation of + its muscles, as in stretching, (of which a case was related in Section <a + href="#sect_VII_1_3">VII. 1. 3</a>.) or by the electric concussion; + afterwards it becomes obedient to sensation, as in violent danger or + fear; and lastly, the muscles become again associated with volition, and + gradually acquire their usual habits of acting together.</p> + + <p>Another phænomenon in palsies is, that when the limbs of one side are + disabled, those 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 resides, and which is capable of being exhausted by fatigue, + and accumulated in rest, is now less expended, whilst one half of the + body is capable of receiving its usual proportion of it, and is hence + derived with greater ease or in greater abundance into the limbs, which + remain unaffected.</p> + + <p><a name="sect_XXXIV_2">II</a>. <a name="sect_XXXIV_2_1">1</a>. The + excess or defect of voluntary exertion produces similar effects upon the + sensual motions, or ideas of the mind, as those already mentioned upon + the muscular fibres. Thus when any violent pain, arising from the defect + of some peculiar stimulus, exists either in the muscular or sensual + systems of fibres, and which cannot be removed by acquiring the defective + stimulus; as in some constitutions convulsions of the muscles are + produced to procure a temporary relief, so in other constitutions + vehement voluntary exertions of the ideas of the mind are produced for + the same purpose; for during this exertion, like that of the muscles, the + pain either vanishes or is diminished: this violent exertion constitutes + madness; and in many cases I have seen the madness take place, and the + convulsions cease, and reciprocally the madness cease, and the + convulsions supervene. See Section <a href="#sect_III_5_8">III. 5. + 8</a>.</p> + + <p><a name="sect_XXXIV_2_2">2</a>. Madness is distinguishable from + delirium, as in the latter the patient knows not the place where he + resides, nor the persons of his friends or attendants, nor is conscious + of any external objects, except when spoken to with a louder voice, or + stimulated with unusual force, and even then he soon relapses into a + state of inattention to every thing about him. Whilst in the former he is + perfectly sensible to every thing external, but has the voluntary powers + of his mind intensely exerted on some particular object of his desire or + aversion, he harbours in his thoughts a suspicion of all mankind, lest + they should counteract his designs; and while he keeps his intentions, + and the motives of his actions profoundly secret; he is perpetually + studying the means of acquiring the object of his wish, or of preventing + or revenging the injuries he suspects.</p> + + <p><a name="sect_XXXIV_2_3">3</a>. A late French philosopher, Mr. + Helvetius, has deduced almost all our actions from this principle of + their relieving us from the ennui or tædium vitæ; and true it is, that + our desires or aversions are the motives of all our voluntary actions; + and human nature seems to excel other animals in the more facil use of + this voluntary power, and on that account is more liable to insanity than + other animals. But in mania this violent exertion of volition is expended + on mistaken objects, and would not be relieved, though we were to gain or + escape the objects, that excite it. Thus I have seen two instances of + madmen, who conceived that they had the itch, and several have believed + they had the venereal infection, without in reality having a symptom of + either of them. They have been perpetually thinking upon this subject, + and some of them were in vain salivated with design of convincing them to + the contrary.</p> + + <p><a name="sect_XXXIV_2_4">4</a>. In the minds of mad people those + volitions alone exist, which are unmixed with sensation; immoderate + suspicion is generally the first symptom, and want of shame, and want of + delicacy about cleanliness. Suspicion is a voluntary exertion of the mind + arising from the pain of fear, which it is exerted to relieve: shame is + the name of a peculiar disagreeable sensation, see Fable of the Bees, and + delicacy about cleanliness arises from another disagreeable sensation. + And therefore are not found in the minds of maniacs, which are employed + solely in voluntary exertions. Hence the most modest women in this + disease walk naked amongst men without any kind of concern, use obscene + discourse, and have no delicacy about their natural evacuations.</p> + + <p><a name="sect_XXXIV_2_5">5</a>. Nor are maniacal people more attentive + to their natural appetites, or to the irritations which surround them, + except as far as may respect their suspicions or designs; for the violent + and perpetual exertions of their voluntary powers of mind prevents their + perception of almost every other object, either of irritation or of + sensation. Hence it is that they bear cold, hunger, and fatigue, with + much greater pertinacity than in their sober hours, and are less injured + by them in respect to their general health. Thus it is asserted by + historians, that Charles the Twelfth of Sweden slept on the snow, wrapped + only in his cloak, at the siege of Frederickstad, and bore extremes of + cold and hunger, and fatigue, under which numbers of his soldiers + perished; because the king was insane with ambition, but the soldier had + no such powerful stimulus to preserve his system from debility and + death.</p> + + <p><a name="sect_XXXIV_2_6">6</a>. Besides the insanities arising from + exertions in consequence of pain, there is also a pleasurable insanity, + as well as a pleasurable delirium; as the insanity of personal vanity, + and that of religious fanaticism. When agreeable ideas excite into motion + the sensorial power of sensation, and this again causes other trains of + agreeable ideas, a constant stream of pleasurable ideas succeeds, and + produces pleasurable delirium. So when the sensorial power of volition + excites agreeable ideas, and the pleasure thus produced excites more + volition in its turn, a constant flow of agreeable voluntary ideas + succeeds; which when thus exerted in the extreme constitutes + insanity.</p> + + <p>Thus when our muscular actions are excited by our sensations of + pleasure, it is termed play; when they are excited by our volition, it is + termed work; and the former of these is attended with less fatigue, + because the muscular actions in play produce in their turn more + pleasurable sensation; which again has the property of producing more + muscular action. An agreeable instance of this I saw this morning. A + little boy, who was tired with walking, begged of his papa to carry him. + "Here," says the reverend doctor, "ride upon my gold-headed cane;" and + the pleased child, putting it between his legs, gallopped away with + delight, and complained no more of his fatigue. Here the aid of another + sensorial power, that of pleasurable sensation, superadded vigour to the + exertion of exhausted volition. Which could otherwise only have been + excited by additional pain, as by the lash of slavery. On this account + where the whole sensorial power has been exerted on the contemplation of + the promised joys of heaven, the saints of all persecuted religions have + borne the tortures of martyrdom with otherwise unaccountable + firmness.</p> + + <p><a name="sect_XXXIV_2_7">7</a>. There are some diseases, which obtain + at least a temporary relief from the exertions of insanity; many + instances of dropsies being thus for a time cured are recorded. An + elderly woman labouring with ascites I twice saw relieved for some weeks + by insanity, the dropsy ceased for several weeks, and recurred again + alternating with the insanity. A man afflicted with difficult respiration + on lying down, with very irregular pulse, and œdematous legs, whom I + saw this day, has for above a week been much relieved in respect to all + those symptoms by the accession of insanity, which is shewn by inordinate + suspicion, and great anger.</p> + + <p>In cases of common temporary anger the increased action of the + arterial system is seen by the red skin, and increased pulse, with the + immediate increase of muscular activity. A friend of mine, when he was + painfully fatigued by riding on horseback, was accustomed to call up + ideas into his mind, which used to excite his anger or indignation, and + thus for a time at least relieved the pain of fatigue. By this temporary + insanity, the effect of the voluntary power upon the whole of his system + was increased; as in the cases of dropsy above mentioned, it would + appear, that the increased action of the voluntary faculty of the + sensorium affected the absorbent system, as well as the secerning + one.</p> + + <p><a name="sect_XXXIV_2_8">8</a>. In respect to relieving inflammatory + pains, and removing fever, I have seen many instances, as mentioned in + Sect. <a href="#sect_XII_2_4">XII. 2. 4</a>. One lady, whom I attended, + had twice at some years interval a locked jaw, which relieved a pain on + her sternum with peripneumony. Two other ladies I saw, who towards the + end of violent peripneumony, in which they frequently lost blood, were at + length cured by insanity supervening. In the former the increased + voluntary exertion of the muscles of the jaw, in the latter that of the + organs of sense, removed the disease; that is, the disagreeable + sensation, which had produced the inflammation, now excited the voluntary + power, and these new voluntary exertions employed or expended the + superabundant sensorial power, which had previously been exerted on the + arterial system, and caused inflammation.</p> + + <p>Another case, which I think worth relating, was of a young man about + twenty; he had laboured under an irritative fever with debility for three + or four weeks, with very quick and very feeble pulse, and other usual + symptoms of that species of typhus, but at this time complained much and + frequently of pain of his legs and feet. When those who attended him were + nearly in despair of his recovery, I observed with pleasure an insanity + of mind supervene: 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 suspicious of his attendants, and calumniated with + vehement oaths his tender mother, who sat weeping by his bed. On this his + pulse became slower and firmer, but the quickness did not for some time + intirely cease, and he gradually recovered. In this case the introduction + of an increased quantity of the power of volition gave vigour to those + movements of the system, which are generally only actuated by the power + of irritation, and of association.</p> + + <p>Another case I recollect of a young man, about twenty-five, who had + the scarlet-fever, with very quick pulse, and an universal eruption on + his skin, and was not without reason esteemed to be in great danger of + his life. After a few days an insanity supervened, which his friends + mistook for delirium, and he gradually recovered, and the cuticle peeled + off. From these and a few other cases I have always esteemed insanity to + be a favourable sign in fevers, and have cautiously distinguished it from + delirium.</p> + + <p><a name="sect_XXXIV_3">III</a>. Another mode of mental exertion to + relieve pain, is by producing a train of ideas not only by the efforts of + volition, as in insanity; but by those of sensation likewise, as in + delirium and sleep. This mental effort is termed reverie, or + somnambulation, and is described more at large in Sect. <a + href="#sect_XIX">XIX</a>. on that subject. But I shall here relate + another case of that wonderful disease, which fell yesterday under my + eye, and to which I have seen many analogous alienations of mind, though + not exactly similar in all circumstances. But as all of them either began + or terminated with pain or convulsion, there can be no doubt but that + they are of epileptic origin, and constitute another mode of mental + exertion to relieve some painful sensation.</p> + + <p><a name="sect_XXXIV_3_1">1</a>. Master A. about nine years old, had + been seized at seven every morning for ten days with uncommon fits, and + had had slight returns in the afternoon. They were supposed to originate + from worms, and had been in vain attempted to be removed by vermifuge + purges. As his fit was expected at seven yesterday morning, I saw him + before that hour; he was asleep, seemed free from pain, and his pulse + natural. About seven he began to complain of pain about his navel, or + more to the left side, and in a few minutes had exertions of his arms and + legs like swimming. He then for half an hour hunted a pack of hounds; as + appeared by his hallooing, and calling the dogs by their names, and + discoursing with the attendants of the chase, describing exactly a day of + hunting, which (I was informed) he had witnessed a year before, going + through all the most minute circumstances of it; calling to people, who + were then present, and lamenting the absence of others, who were then + also absent. After this scene he imitated, as he lay in bed, some of the + plays of boys, as swimming and jumping. He then sung an English and then + an Italian song; part of which with his eyes open, and part with them + closed, but could not be awakened or excited by any violence, which it + was proper to use.</p> + + <p>After about an hour he came suddenly to himself with apparent + surprise, and seemed quite ignorant of any part of what had passed, and + after being apparently well for half an hour, he suddenly fell into a + great stupor, with slower pulse than natural, and a slow moaning + respiration, in which he continued about another half hour, and then + recovered.</p> + + <p>The sequel of this disease was favourable; he was directed one grain + of opium at six every morning, and then to rise out of bed; at half past + six he was directed fifteen drops of laudanum in a glass of wine and + water. The first day the paroxysm became shorter, and less violent. The + dose of opium was increased to one-half more, and in three or four days + the fits left him. The bark and filings of iron were also exhibited twice + a day; and I believe the complaint returned no more.</p> + + <p><a name="sect_XXXIV_3_2">2</a>. In this paroxysm it must be observed, + that he began with pain, and ended with stupor, in both circumstances + resembling a fit of epilepsy. And that therefore the exertions both of + mind and body, both the voluntary ones, and those immediately excited by + pleasurable sensation, were exertions to relieve pain.</p> + + <p>The hunting scene appeared to be rather an act of memory than of + imagination, and was therefore rather a voluntary exertion, though + attended with the pleasurable eagerness, which was the consequence of + those ideas recalled by recollection, and not the cause of them.</p> + + <p>These ideas thus voluntarily recollected were succeeded by sensations + of pleasure, though his senses were unaffected by the stimuli of visible + or audible objects; or so weakly excited by them as not to produce + sensation or attention. And the pleasure thus excited by volition + produced other ideas and other motions in consequence of the sensorial + power of sensation. Whence the mixed catenations of voluntary and + sensitive ideas and muscular motions in reverie; which, like every other + kind of vehement exertion, contribute to relieve pain, by expending a + large quantity of sensorial power.</p> + + <p>Those fits generally commence during sleep, from whence I suppose they + have been thought to have some connection with sleep, and have thence + been termed Somnambulism; but their commencement during sleep is owing to + our increased excitability by internal sensations at that time, as + explained in Sect. <a href="#sect_XVIII_14">XVIII. 14</a>. and <a + href="#sect_XVIII_15">15</a>., and not to any similitude between reverie + and sleep.</p> + + <p><a name="sect_XXXIV_3_3">3</a>. I was once concerned for a very + elegant and ingenious young lady, who had a reverie on alternate days, + which continued nearly the whole day; and as in her days of disease she + took up the same kind of ideas, which she had conversed about on the + alternate day before, and could recollect nothing of them on her + well-day; she appeared to her friends to possess two minds. This case + also was of epileptic kind, and was cured, with some relapses, by opium + administered before the commencement of the paroxysm.</p> + + <p><a name="sect_XXXIV_3_4">4</a>. Whence it appears, that the methods of + relieving inflammatory pains, is by removing all stimulus, as by + venesection, cool air, mucilaginous diet, aqueous potation, silence, + darkness.</p> + + <p>The methods of relieving pains from defect of stimulus is by supplying + the peculiar stimulus required, as of food, or warmth.</p> + + <p>And the general method of relieving pain is by exciting into action + some great part of the system for the purpose of expending a part of the + sensorial power. This is done either by exertion of the voluntary ideas + and muscles, as in insanity and convulsion; or by exerting both voluntary + and sensitive motions, as in reverie; or by exciting the irritative + motions by wine or opium internally, and by the warm bath or blisters + externally; or lastly, by exciting the sensitive ideas by good news, + affecting stories, or agreeable passions.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXXV">XXXV</a>.</h3> + +<p class="center" style="margin-top: 2em;">DISEASES OF ASSOCIATION.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXXV_1">I</a>. <a href="#sect_XXXV_1_1">1</a>. + <i>Sympathy or consent of parts. Primary and secondary parts of an + associated train of motions reciprocally affect each other. Parts of + irritative trains of motion affect each other in four ways. Sympathies of + the skin and stomach. Flushing of the face after a meal. Eruption of the + small-pox on the face. Chilness after a meal.</i> <a + href="#sect_XXXV_1_2">2</a>. <i>Vertigo from intoxication.</i> <a + href="#sect_XXXV_1_3">3</a>. <i>Absorption from the lungs and pericardium + by emetics. In vomiting the actions of the stomach are decreased, not + increased. Digestion strengthened after an emetic. Vomiting from + deficiency of sensorial power.</i> <a href="#sect_XXXV_1_4">4</a>. + <i>Dyspnœa from cold bathing. Slow pulse from digitalis. Death from + gout in the stomach.</i> <a href="#sect_XXXV_2">II</a>. <a + href="#sect_XXXV_2_1">1</a>. <i>Primary and secondary parts of sensitive + associations affect each other. Pain from gall-stone, from urinary stone, + Hemicrania. Painful epilepsy.</i> <a href="#sect_XXXV_2_2">2</a>. <i>Gout + and red face from inflamed liver. Shingles from inflamed kidney.</i> <a + href="#sect_XXXV_2_3">3</a>. <i>Coryza from cold applied to the feet. + Pleurisy. Hepatitis.</i> <a href="#sect_XXXV_2_4">4</a>. <i>Pain of + shoulders from inflamed liver.</i> <a href="#sect_XXXV_3">III</a>. + <i>Diseases from the associations of ideas.</i></p> + +</blockquote> + + <p><a name="sect_XXXV_1">I</a>. <a name="sect_XXXV_1_1">1</a>. Many + synchronous and successive motions of our muscular fibres, and of our + organs of sense, or ideas, become associated so as to form indissoluble + tribes or trains of action, as shewn in Section <a href="#sect_X">X</a>. + on Associate Motions. Some constitutions more easily establish these + associations, whether by voluntary, sensitive, or irritative repetitions, + and some more easily lose them again, as shewn in Section <a + href="#sect_XXXI">XXXI</a>. on Temperaments.</p> + + <p>When the beginning of such a train of actions becomes by any means + disordered, the succeeding part is liable to become disturbed in + consequence, and this is commonly termed sympathy or consent of parts by + the writers of medicine. For the more clear understanding of these + sympathies we must consider 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 secondary or sympathetic ones.</p> + + <p>The primary and secondary 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 less energy. 3. The former may act with + less, and the latter with greater energy. 4. They may both act with less + energy than natural. I shall now give an example of each kind of these + modes of action, and endeavour to shew, that though the primary and + secondary parts of these trains or tribes of motion are connected by + irritative association, or their previous habits of acting together, as + described in Sect. <a href="#sect_XX">XX</a>. on Vertigo. Yet that their + acting with similar or dissimilar degrees of energy, depends on the + greater or less quantity of sensorial power, which the primary part of + the train expends in its exertions.</p> + + <p>The actions of the stomach constitute so important a part of the + associations of both irritative and sensitive motions, that it is said to + sympathize with almost every part of the body; the first example, which I + shall adduce to shew that both the primary and secondary parts of a train + of irritative associations of motion act with increased energy, is taken + from the consent of the skin with this organ. When the action of the + fibres of the stomach is increased, as by the stimulus of a full meal, + the exertions of the cutaneous arteries of the face become increased by + their irritative associations with those of the stomach, and a glow or + flushing of the face succeeds. For the small vessels of the skin of the + face having been more accustomed to the varieties of action, from their + frequent exposure to various degrees of cold and heat become more easily + excited into increased action, than those of the covered parts of our + bodies, and thus act with more energy from their irritative or sensitive + associations with the stomach. On this account in small-pox the eruption + in consequence of the previous affection of the stomach breaks out a day + sooner on the face than on the hands, and two days sooner than on the + trunk, and recedes in similar times after maturation.</p> + + <p>But secondly, in weaker constitutions, that is, in those who possess + less sensorial power, so much of it is expended in the increased actions + of the fibres of the stomach excited by the stimulus of a meal, that a + sense of chilness succeeds instead of the universal glow above mentioned; + and thus the secondary part of the associated train of motions is + diminished in energy, in consequence of the increased activity of the + primary part of it.</p> + + <p><a name="sect_XXXV_1_2">2</a>. Another instance of a similar kind, + where the secondary part of the train acts with less energy in + consequence of the greater exertions of the primary part, is the vertigo + attending intoxication; in this circumstance so much sensorial power is + expended on the stomach, and on its nearest or more strongly associated + motions, as those of the subcutaneous vessels, and probably of the + membranes of some internal viscera, that the irritative motions of the + retina become imperfectly exerted from deficiency of sensorial power, as + explained in Sect. <a href="#sect_XX">XX</a>. and <a + href="#sect_XXI_3">XXI. 3</a>. on Vertigo and on Drunkenness, and hence + the staggering inebriate cannot completely balance himself by such + indistinct vision.</p> + + <p><a name="sect_XXXV_1_3">3</a>. An instance of the third circumstance, + where the primary part of a train of irritative motions acts with less, + and the secondary part with greater energy, may be observed by making the + following experiment. If a person lies with his arms and shoulders out of + bed, till they become cold, a temporary coryza or catarrh is produced; so + that the passage of the nostrils becomes totally obstructed; at least + this happens to many people; and then on covering the arms and shoulders, + till they become warm, the passage of the nostrils ceases again to be + obstructed, and a quantity of mucus is discharged from them. In this case + the quiescence of the vessels of the skin of the arms and shoulders, + occasioned by exposure to cold air, produces by irritative association an + increased action of the vessels of the membrane of the nostrils; and the + accumulation of sensorial power during the torpor of the arms and + shoulders is thus expended in producing a temporary coryza or + catarrh.</p> + + <p>Another instance may be adduced from the sympathy or consent of the + motions of the stomach with other more distant links of the very + extensive tribes or trains of irritative motions associated with them, + described in Sect. <a href="#sect_XX">XX</a>. on Vertigo. When the + actions of the fibres of the stomach are diminished or inverted, the + actions of the absorbent vessels, which take up the mucus from the lungs, + pericardium, and other cells of the body, become increased, and absorb + the fluids accumulated in them with greater avidity, as appears from the + exhibition of foxglove, antimony, or other emetics in cases of anasarca, + attended with unequal pulse and difficult respiration.</p> + + <p>That the act of nausea and vomiting is a decreased exertion of the + fibres of the stomach may be thus deduced; when an emetic medicine is + administered, it produces the pain of sickness, as a disagreeable taste + in the mouth produces the pain of nausea; these pains, like that of + hunger, or of cold, or like those, which are usually termed nervous, as + the head-ach or hemicrania, do not excite the organ into greater action; + but in this case I imagine the pains of sickness or of nausea counteract + or destroy the pleasurable sensation, which seems necessary to digestion, + as shewn in Sect. <a href="#sect_XXXIII_1_1">XXXIII. 1. 1</a>. The + peristaltic motions of the fibres of the stomach become enfeebled by the + want of this stimulus of pleasurable sensation, and in consequence stop + for a time, and then become inverted; for they cannot become inverted + without being previously stopped. Now that this inversion of the trains + of motion of the fibres of the stomach is owing to the deficiency of + pleasurable sensation is evinced from this circumstance, that a nauseous + idea excited by words will produce vomiting as effectually us a nauseous + drug.</p> + + <p>Hence it appears, that the act of nausea or vomiting expends less + sensorial power than the usual peristaltic motions of the stomach in the + digestion of our aliment; and that hence there is a greater quantity of + sensorial power becomes accumulated in the fibres of the stomach, and + more of it in consequence to spare for the action of those parts of the + system, which are thus associated with the stomach, as of the whole + absorbent series of vessels, and which are at the same time excited by + their usual stimuli.</p> + + <p>From this we can understand, how after the operation of an emetic the + stomach becomes more irritable and sensible to the stimulus, and the + pleasure of food; since as the sensorial power becomes accumulated during + the nausea and vomiting, the digestive power is afterwards exerted more + forceably for a time. It should, however, be here remarked, that though + vomiting is in general produced by the defect of this stimulus of + pleasurable sensation, as when a nauseous drug is administered; yet in + long continued vomiting, as in sea-sickness, or from habitual + dram-drinking, it arises from deficiency of sensorial power, which in the + former case is exhausted by the increased exertion of the irritative + ideas of vision, and in the latter by the frequent application of an + unnatural stimulus.</p> + + <p><a name="sect_XXXV_1_4">4</a>. An example of the fourth circumstance + above mentioned, where both the primary and secondary parts of a train of + motions proceed with energy less than natural, may be observed in the + dyspnœa, which occurs in going into a very cold bath, and which has + been described and explained in Sect. <a href="#sect_XXXII_3_2">XXXII. 3. + 2</a>.</p> + + <p>And by the increased debility of the pulsations of the heart and + arteries during the operation of an emetic. Secondly, from the slowness + and intermission of the pulsations of the heart from the incessant + efforts to vomit occasioned by an overdose of digitalis. And thirdly, + from the total stoppage of the motions of the heart, or death, in + consequence of the torpor of the stomach, when affected with the + commencement or cold paroxysm of the gout. See Sect. <a + href="#sect_XXV_17">XXV. 17</a>.</p> + + <p><a name="sect_XXXV_2">II</a>. <a name="sect_XXXV_2_1">1</a>. The + primary and secondary parts of the trains of sensitive association + reciprocally affect each other in different manners. 1. The increased + sensation of the primary part may cease, when that of the secondary part + commences. 2. The increased action of the primary part may cease, when + that of the secondary part commences. 3. The primary part may have + increased sensation, and the secondary part increased action. 4. The + primary part may have increased action, and the secondary part increased + sensation.</p> + + <p>Examples of the first mode, where the increased sensation of the + primary part of a train of sensitive association ceases, when that of the + secondary part commences, are not unfrequent; as this is the general + origin of those pains, which continue some time without being attended + with inflammation, such as the pain at the pit of the stomach from a + stone at the neck of the gall-bladder, and the pain of strangury in the + glans penis from a stone at the neck of the urinary bladder. In both + these cases the part, which is affected secondarily, is believed to be + much more sensible than the part primarily affected, as described in the + catalogue of diseases, Class II. 1. 1. 11. and IV. 2. 2. 2. and IV. 2. 2. + 4.</p> + + <p>The hemicrania, or nervous headach, as it is called, when it + originates from a decaying tooth, is another disease of this kind; as the + pain of the carious tooth always ceases, when the pain over one eye and + temple commences. And it is probable, that the violent pains, which + induce convulsions in painful epilepsies, are produced in the same + manner, from a more sensible part sympathizing with a diseased one of + less sensibility. See Catalogue of Diseases, Class IV. 2. 2. 8. and III. + 1. 1. 6.</p> + + <p>The last tooth, or dens sapientiæ, of the upper jaw most frequently + decays first, and is liable to produce pain over the eye and temple of + that side. The last tooth of the under-jaw is also liable to produce a + similar hemicrania, when it begins to decay. When a tooth in the + upper-jaw is the cause of the headach, a slighter pain is sometimes + perceived on the cheek-bone. And when a tooth in the lower-jaw is the + cause of headach, a pain sometimes affects the tendons of the muscles of + the neck, which are attached near the jaws. But the clavus hystericus, or + pain about the middle of the parietal bone on one side of the head, I + have seen produced by the second of the molares, or grinders, of the + under-jaw; of which I shall relate the following case. See Class IV. 2. + 2. 8.</p> + + <p>Mrs. ——, about 30 years of age, was seized with great pain + about the middle of the right parietal bone, which had continued a whole + day before I saw her, and was so violent as to threaten to occasion + convulsions. Not being able to detect a decaying tooth, or a tender one, + by examination with my eye, or by striking them with a tea-spoon, and + fearing bad consequences from her tendency to convulsion, I advised her + to extract the last tooth of the under-jaw on the affected side; which + was done without any good effect. She was then directed to lose blood, + and to take a brisk cathartic; and after that had operated, about 60 + drops of laudanum were given her, with large doses of bark; by which the + pain was removed. In about a fortnight she took a cathartic medicine by + ill advice, and the pain returned with greater violence in the same + place; and, before I could arrive, as she lived 30 miles from me, she + suffered a paralytic stroke; which affected her limbs and her face on one + side, and relieved the pain of her head.</p> + + <p>About a year afterwards I was again called to her on account of a pain + as violent as before exactly on the same part of the other parietal bone. + On examining her mouth I found the second molaris of the under-jaw on the + side before affected was now decayed, and concluded, that this tooth had + occasioned the stroke of the palsy by the pain and consequent exertion it + had caused. On this account I earnestly entreated her to allow the sound + molaris of the same jaw opposite to the decayed one to be extracted; + which was forthwith done, and the pain of her head immediately ceased, to + the astonishment of her attendants.</p> + + <p>In the cases above related of the pain existing in a part distant from + the seat of the disease, the pain is owing to defect of the usual motions + of the painful part. This appears from the coldness, paleness, and + emptiness of the affected vessels, or of the extremities of the body in + general, and from there being no tendency to inflammation. The increased + action of the primary part of these associated motions, as of the hepatic + termination of the bile-duct; from the stimulus of a gall-stone, or of + the interior termination of the urethra from the stimulus of a stone in + the bladder, or lastly, of a decaying tooth in hemicrania, deprives the + secondary part of these associated motions, namely, the exterior + terminations of the bile-duct or urethra, or the pained membranes of the + head in hemicrania, of their natural share of sensorial power: and hence + the secondary parts of these sensitive trains of association become + pained from the deficiency of their usual motions, which is accompanied + with deficiency of secretions and of heat. See Sect. <a + href="#sect_IV_5">IV. 5</a>. <a href="#sect_XII_5_3">XII. 5. 3</a>. <a + href="#sect_XXXIV_1">XXXIV. 1</a>.</p> + + <p>Why does the pain of the primary part of the association cease, when + that of the secondary part commences? This is a question of intricacy, + but perhaps not inexplicable. The pain of the primary part of these + associated trains of motion was owing to too great stimulus, as of the + stone at the neck of the bladder, and was consequently caused by too + great action of the pained part. This greater action than natural of the + primary part of these associated motions, by employing or expending the + sensorial power of irritation belonging to the whole associated train of + motions, occasioned torpor, and consequent pain in the secondary part of + the associated train; which was possessed of greater sensibility than the + primary part of it. Now the great pain of the secondary part of the + train, as soon as it commences, employs or expends the sensorial power of + sensation belonging to the whole associated train of motions; and in + consequence the motions of the primary part, though increased by the + stimulus of an extraneous body, cease to be accompanied with pain or + sensation.</p> + + <p>If this mode of reasoning be just it explains a curious fact, why when + two parts of the body are strongly stimulated, the pain is felt only in + one of them, though it is possible by voluntary attention it may be + alternately perceived in them both. In the same manner, when two new + ideas are presented to us from the stimulus of external bodies, we attend + to but one of them at a time. In other words, when one set of fibres, + whether of the muscles or organs of sense, contract so strongly as to + excite much sensation; another set of fibres contracting more weakly do + not excite sensation at all, because the sensorial power of sensation is + pre-occupied by the first set of fibres. So we cannot will more than one + effect at once, though by associations previously formed we can move many + fibres in combination.</p> + + <p>Thus in the instances above related, the termination of the bile duct + in the duodenum, and the exterior extremity of the urethra, are more + sensible than their other terminations. When these parts are deprived of + their usual motions by deficiency of sensorial power, as above explained, + they become painful according to law the fifth in Section <a + href="#sect_IV">IV</a>. and the less pain originally excited by the + stimulus of concreted bile, or of a stone at their other extremities + ceases to be perceived. Afterwards, however, when the concretions of + bile, or the stone on the urinary bladder, become more numerous or + larger, the pain from their increased stimulus becomes greater than the + associated 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 + stomach, ceases to be perceived.</p> + + <p><a name="sect_XXXV_2_2">2</a>. Examples of the second mode, where the + increased action of the primary part of a train of sensitive association + ceases, when that of the secondary part commences, are also not + unfrequent; as this is the usual manner of the translation of + inflammations from internal to external parts of the system, such as when + an inflammation of the liver or stomach is translated to the membranes of + the foot, and forms the gout; or to the skin of the face, and forms the + rosy drop; or when an inflammation of the membranes of the kidneys is + translated to the skin of the loins, and forms one kind of herpes, called + shingles; in these cases by whatever cause the original inflammation may + have been produced, as the secondary part of the train of sensitive + association is more sensible, it becomes exerted with greater violence + than the first part of it; and by both its increased pain, and the + increased motion of its fibres, so far diminishes or exhausts the + sensorial power of sensation; that the primary part of the train being + less sensible ceases both to feel pain, and to act with unnatural + energy.</p> + + <p><a name="sect_XXXV_2_3">3</a>. Examples of the third mode, where the + primary part of a train of sensitive association of motions may + experience increased sensation, and the secondary part increased action, + are likewise not unfrequent; as it is in this manner that most + inflammations commence. Thus, after standing some time in snow, the feet + become affected with the pain of cold, and a common coryza, or + inflammation of the membrane of the nostrils, succeeds. It is probable + that the internal inflammations, as pleurisies, or hepatitis, which are + produced after the cold paroxysm of fever, originate in the same manner + from the sympathy of those parts with some others, which were previously + pained from quiescence; as happens to various parts of the system during + the cold fits of fevers. In these cases it would seem, that the sensorial + power of sensation becomes accumulated during the pain of cold, as the + torpor of the vessels occasioned by the defect of heat contributes to the + increase or accumulation of the sensorial power of irritation, and that + both these become exerted on some internal part, which was not rendered + torpid by the cold which affected the external parts, nor by its + association with them; or which sooner recovered its sensibility. This + requires further consideration.</p> + + <p><a name="sect_XXXV_2_4">4</a>. An example of the fourth mode, or where + the primary part of a sensitive association of motions may have increased + action, and the secondary part increased sensation, may be taken from the + pain of the shoulder, which attends inflammation of the membranes of the + liver, see Class IV. 2. 2. 9.; in this circumstance so much sensorial + power seems to be expended in the violent actions and sensations of the + inflamed membranes of the liver, that the membranes associated with them + become quiescent to their usual stimuli, and painful in consequence.</p> + + <p>There may be other modes in which the primary and secondary parts of + the trains of associated sensitive motions may reciprocally affect each + other, as may be seen by looking over Class IV. in the catalogue of + diseases; all which may probably be resolved into the plus and minus of + sensorial power, but we have not yet had sufficient observations made + upon them with a view to this doctrine.</p> + + <p><a name="sect_XXXV_3">III</a>. The associated trains of our ideas may + have sympathies, and their primary and secondary parts affect each other + in some manner similar to those above described; and may thus occasion + various curious phenomena not yet adverted to, besides those explained in + the Sections on Dreams, Reveries, Vertigo, and Drunkenness; and may thus + disturb the deductions of our reasonings, as well as the streams of our + imaginations; present us with false degrees of fear, attach unfounded + value to trivial circumstances; give occasion to our early prejudices and + antipathies; and thus embarrass the happiness of our lives. A copious and + curious harvest might be reaped from this province of science, in which, + however, I shall not at present wield my sickle.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXXVI">XXXVI</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE PERIODS OF DISEASES.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXXVI_1">I</a>. <i>Muscles excited by volition soon + cease to contract, or by sensation, or by irritation, owing to the + exhaustion of sensorial power. Muscles subjected to less stimulus have + their sensorial power accumulated. Hence the periods of some fevers. Want + of irritability after intoxication.</i> <a href="#sect_XXXVI_2">II</a>. + <a href="#sect_XXXVI_2_1">1</a>. <i>Natural actions catenated with daily + habits of life.</i> <a href="#sect_XXXVI_2_2">2</a>. <i>With solar + periods. Periods of sleep. Of evacuating the bowels.</i> <a + href="#sect_XXXVI_2_3">3</a>. <i>Natural actions catenated with lunar + periods. Menstruation. Venereal orgasm of animals. Barrenness.</i> <a + href="#sect_XXXVI_3">III</a>. <i>Periods of diseased animal actions from + stated returns of nocturnal cold, from solar and lunar influence. Periods + of diurnal fever, hectic fever, quotidian, tertian, quartan fever. + Periods of gout, pleurisy, of fevers with arterial debility, and with + arterial strength, Periods of rhaphania, of nervous cough, hemicrania, + arterial hæmorrhages, hæmorrhoids, hæmoptoe, epilepsy, palsy, apoplexy, + madness.</i> <a href="#sect_XXXVI_4">IV</a>. <i>Critical days depend on + lunar periods. Lunar periods in the small pox.</i></p> + +</blockquote> + + <p><a name="sect_XXXVI_1">I</a>. If any of our muscles be made to + contract violently by the power of volition, as those of the fingers, + when any one hangs by his hands on a swing, fatigue soon ensues; and the + muscles cease to act owing to the temporary exhaustion of the spirit of + animation; as soon as this is again accumulated in the muscles, they are + ready to contract again by the efforts of volition.</p> + + <p>Those violent muscular actions induced by pain become in the same + manner intermitted and recurrent; as in labour-pains, vomiting, tenesmus, + strangury; owing likewise to the temporary exhaustion of the spirit of + animation, as above mentioned.</p> + + <p>When any stimulus continues long to act with unnatural violence, so as + to produce too energetic action of any of our moving organs, those + motions soon cease, though the stimulus continues to act; as in looking + long on a bright object, as on an inch-square of red silk laid on white + paper in the sunshine. See Plate I. in Sect. <a href="#sect_III_1">III. + 1</a>.</p> + + <p>On the contrary, where less of the stimulus of volition, sensation, or + irritation, have been applied to a muscle than usual; there appears to be + an accumulation of the spirit of animation in the moving organ; by which + it is liable to act with greater energy from less quantity of stimulus, + than was previously necessary to excite it into so great action; as after + having been immersed in snow the cutaneous vessels of our hands are + excited into stronger action by the stimulus of a less degree of heat, + than would previously have produced that effect.</p> + + <p>From hence the periods of some fever-fits may take their origin, + either simply, or by their accidental coincidence with lunar and solar + periods, or with the diurnal periods of heat and cold, to be treated of + below; for during the cold fit at the commencement of a fever, from + whatever cause that cold fit may have been induced, it follows, 1. That + the spirit of animation must become accumulated in the parts, which exert + during this cold fit less than their natural quantity of action. 2. If + the cause producing the cold fit does not increase, or becomes + diminished; the parts before benumbed or inactive become now excitable by + smaller stimulus, and are thence thrown into more violent action than is + natural; that is a hot fit succeeds the cold one. 3. By the energetic + action of the system during the hot fit, if it continues long, an + exhaustion of the spirit of animation takes place; and another cold fit + is liable to succeed, from the moving system not being excitable into + action from its usual stimulus. This inirritability of the system from a + too great previous stimulus, and consequent exhaustion of sensorial + power, is the cause of the general debility, and sickness, and head-ach, + some hours after intoxication. And hence we see one of the causes 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 solar or lunar + periods.</p> + + <p>When besides the tendency to quiescence occasioned by the expenditure + of sensorial power during the hot fit of fever, some other cause of + torpor, as the solar or lunar periods, is necessary to the introduction + of a second cold fit; the fever becomes of the intermittent kind; that + is, there is a space of time intervenes between the end of the hot fit, + and the commencement of the next cold one. But where no exteriour cause + is necessary to the introduction of the second cold fit; no such interval + of health intervenes; but the second cold fit commences, as soon as the + sensorial power is sufficiently exhausted by the hot fit; and the fever + becomes continual.</p> + + <p><a name="sect_XXXVI_2">II</a>. <a name="sect_XXXVI_2_1">1</a>. The + following are natural animal actions, which are frequently catenated with + our daily habits of life, as well as excited by their natural + irritations. The periods of hunger and thirst become catenated with + certain portions of time, or degrees of exhaustion, or other diurnal + habits of life. And if the pain of hunger be not relieved by taking food + at the usual time, it is liable to cease till the next period of time or + other habits recur; this is not only true in respect to our general + desire of food, but the kinds of it also are governed by this periodical + habit; insomuch that beer taken to breakfast will disturb the digestion + of those, who have been accustomed to tea; and tea taken at dinner will + disagree with those, who have been accustomed to beer. Whence it happens, + that those, who have weak stomachs, will be able to digest more food, if + they take their meals at regular hours; because they have both the + stimulus of the aliment they take, and the periodical habit, to assist + their digestion.</p> + + <p>The periods of emptying the bladder are not only dependent on the + acrimony or distention of the water in it, but are frequently catenated + with external cold applied to the skin, as in cold bathing, or washing + the hands; or with other habits of life, as many are accustomed to empty + the bladder before going to bed, or into the house after a journey, and + this whether it be full or not.</p> + + <p>Our times of respiration are not only governed by the stimulus of the + blood in the lungs, or our desire of fresh air, but also by our attention + to the hourly objects before us. Hence when a person is earnestly + contemplating an idea of grief, he forgets to breathe, till the sensation + in his lungs becomes very urgent; and then a sigh succeeds for the + purpose of more forceably pushing forwards the blood, which is + accumulated in the lungs.</p> + + <p>Our times of respiration are also frequently governed in part by our + want of a steady support for the actions of our arms, and hands, as in + threading a needle, or hewing wood, or in swimming; when we are intent + upon these objects, we breathe at the intervals of the exertion of the + pectoral muscles.</p> + + <p><a name="sect_XXXVI_2_2">2</a>. The following natural animal actions + are influenced by solar periods. The periods of sleep and of waking + depend much on the solar period, for we are inclined to sleep at a + certain hour, and to awake at a certain hour, whether we have had more or + less fatigue during the day, if within certain limits; and are liable to + wake at a certain hour, whether we went to bed earlier or later, within + certain limits. Hence it appears, that those who complain of want of + sleep, will be liable to sleep better or longer, if they accustom + themselves to go to rest, and to rise, at certain hours.</p> + + <p>The periods of evacuating the bowels are generally connected with some + part of the solar day, as well as with the acrimony or distention + occasioned by the feces. Hence one method of correcting costiveness is by + endeavouring to establish a habit of evacuation at a certain hour of the + day, as recommended by Mr. Locke, which may be accomplished by using + daily voluntary efforts at those times, joined with the usual stimulus of + the material to be evacuated.</p> + + <p><a name="sect_XXXVI_2_3">3</a>. The following natural animal actions + are connected with lunar periods. 1. The periods of female menstruation + are connected with lunar periods to great exactness, in some instances + even to a few hours. These do not commence or terminate at the full or + change, or at any other particular part of the lunation, but after they + have commenced at any part of it, they continue to recur at that part + with great regularity, unless disturbed by some violent circumstance, as + explained in Sect. <a href="#sect_XXXII_6">XXXII. No. 6</a>. their return + is immediately caused by deficient venous absorption, which is owing to + the want of the stimulus, designed by nature, of amatorial copulation, or + of the growing fetus. When the catamenia returns sooner than the period + of lunation, it shows a tendency of the constitution to inirritability; + that is to debility, or deficiency of sensorial power, and is to be + relieved by small doses of steel and opium.</p> + + <p>The venereal orgasm of birds and quadrupeds seems to commence, or + return about the most powerful lunations at the vernal or autumnal + equinoxes; but if it be disappointed of its object, it is said to recur + at monthly periods; in this respect resembling the female catamenia. + Whence it is believed, that women are more liable to become pregnant at + or about the time of their catamenia, than at the intermediate times; and + on this account they are seldom much mistaken in their reckoning of nine + lunar periods from the last menstruation; the inattention to this may + sometimes have been the cause of supposed barrenness, and is therefore + worth the observation of those, who wish to have children.</p> + + <p><a name="sect_XXXVI_3">III</a>. We now come to the periods of diseased + animal actions. The periods of fever-fits, which depend on the stated + returns of nocturnal cold, are discussed in Sect. <a + href="#sect_XXXII_3">XXXII. 3</a>. Those, which originate or recur at + solar or lunar periods, are also explained in Section <a + href="#sect_XXXII_6">XXXII. 6</a>. These we shall here enumerate; + observing, however, that it is not more surprising, that the influence of + the varying attractions of the sun and moon, should raise the ocean into + mountains, than that it should affect the nice sensibilities of animal + bodies; though the manner of its operation on them is difficult to be + understood. It is probable however, that as this influence gradually + lessens during the course of the day, or of the lunation, or of the year, + some actions of our system become less and less; till at length a total + quiescence of some part is induced; which is the commencement of the + paroxysms of fever, of menstruation, of pain with decreased action of the + affected organ, and of consequent convulsion.</p> + + <p><a name="sect_XXXVI_3_1">1</a>. A diurnal fever in some weak people is + distinctly observed to come on towards evening, and to cease with a moist + skin early in the morning, obeying the solar periods. Persons of weak + constitutions are liable to get into better spirits at the access of the + hot fit of this evening fever; and are thence inclined to sit up late; + which by further enfeebling them increases the disease; whence they lose + their strength and their colour.</p> + + <p><a name="sect_XXXVI_3_2">2</a>. The periods of hectic fever, supposed + to arise from absorption of matter, obeys the diurnal periods like the + above, having the exacerbescence towards evening, and its remission early + in the morning, with sweats, or diarrhœa, or urine with white + sediment.</p> + + <p><a name="sect_XXXVI_3_3">3</a>. The periods of quotidian fever are + either catenated with solar 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 use in knowing with what + circumstances the periodical return or new morbid motions are conjoined, + as the most effectual times of exhibiting the proper medicines are thus + determined. So if the torpor, which ushers in an ague fit, is catenated + with the lunar day: it is known, when the bark or opium must be given, so + as to exert its principal effect about the time of the expected return. + Solid opium should be given about an hour before the expected cold fit; + liquid opium and wine about half an hour; the bark repeatedly for six or + eight hours previous to the expected return.</p> + + <p><a name="sect_XXXVI_3_4">4</a>. The periods of tertian fevers, + reckoned from the commencement of one cold fit to the commencement of the + next cold fit, recur with solar intervals of forty-eight hours, or with + lunar ones of about fifty hours. When these of recurrence begin one or + two hours earlier than the solar period, it shews, that the torpor or + cold fit is produced by less external influence; and therefore that it is + more liable to degenerate into a fever with only remissions; so when + menstruation recurs sooner than the period of lunation, it shews a + tendency of the habit to torpor of inirritability.</p> + + <p><a name="sect_XXXVI_3_5">5</a>. The periods of quartan fevers return + at solar intervals of seventy-two hours, or at lunar ones of about + seventy-four hours and an half. This kind of ague appears most in moist + cold autumns, and in cold countries replete with marshes. It is attended + with greater debility, and its cold access more difficult to prevent. For + where there is previously a deficiency of sensorial power, the + constitution is liable to run into greater torpor from any further + diminution of it; two ounces of bark and some steel should be given on + the day before the return of the cold paroxysm, and a pint of wine by + degrees a few hours before its return, and thirty drops of laudanum one + hour before the expected cold fit.</p> + + <p><a name="sect_XXXVI_3_6">6</a>. The periods of the gout generally + commence about an hour before sun-rise, which is usually the coldest part + of the twenty-four hours. The greater periods of the gout seem also to + observe the solar influence, returning about the same season of the + year.</p> + + <p><a name="sect_XXXVI_3_7">7</a>. The periods of the pleurisy recur with + exacerbation of the pain and fever about sun-set, at which time + venesection is of most service. The same may be observed of the + inflammatory rheumatism, and other fevers with arterial strength, which + seem to obey solar periods; and those with debility seem to obey lunar + ones.</p> + + <p><a name="sect_XXXVI_3_8">8</a>. The periods of fevers with arterial + debility seem to obey the lunar day, having their access daily nearly an + hour later; and have sometimes two accesses in a day, resembling the + lunar effects upon the tides.</p> + + <p><a name="sect_XXXVI_3_9">9</a>. The periods of rhaphania, or + convulsions of the limbs from rheumatic pains, seem to be connected with + solar influence, returning at nearly the same hour for weeks together, + unless disturbed by the exhibition of powerful doses of opium.</p> + + <p>So the periods of Tussis ferina, or violent cough with slow pulse, + called nervous cough, recurs by solar periods. Five grains of opium, + given at the time the cough commenced disturbed the period, from seven in + the evening to eleven, at which time it regularly returned for some days, + during which time the opium was gradually omitted. Then 120 drops of + laudanum were given an hour before the access of the cough, and it + totally ceased. The laudanum was continued a fortnight, and then + gradually discontinued.</p> + + <p><a name="sect_XXXVI_3_10">10</a>. The periods of hemicrania, and of + painful epilepsy, are liable to obey lunar periods, both in their diurnal + returns, and in their greater periods of weeks, but are also induced by + other exciting causes.</p> + + <p><a name="sect_XXXVI_3_11">11</a>. The periods of arterial hæmorrhages + seem to return at solar periods about the same hour of the evening or + morning. Perhaps the venous hæmorrhages obey the lunar periods, as the + catamenia, and hæmorrhoids.</p> + + <p><a name="sect_XXXVI_3_12">12</a>. The periods of the hæmorrhoids, or + piles, in some recur monthly, in others only at the greater lunar + influence about the equinoxes.</p> + + <p><a name="sect_XXXVI_3_13">13</a>. The periods of hæmoptoe sometimes + obey solar influence, recurring early in the morning for several days; + and sometimes lunar periods, recurring monthly; and sometimes depend on + our hours of sleep. See Class I. 2. 1. 9.</p> + + <p><a name="sect_XXXVI_3_14">14</a>. Many of the first periods of + epileptic fits obey the monthly lunation with some degree of accuracy; + others recur only at the most powerful lunations before the vernal + equinox, and after the autumnal one; but when the constitution has gained + a habit of relieving disagreeable sensations by this kind of exertion, + the fit recurs from any slight cause.</p> + + <p><a name="sect_XXXVI_3_15">15</a>. The attack of palsy and apoplexy are + known to recur with great frequency about the equinoxes.</p> + + <p><a name="sect_XXXVI_3_16">16</a>. There are numerous instances of the + effect of the lunations upon the periods of insanity, whence the name of + lunatic has been given to those afflicted with this disease.</p> + + <p><a name="sect_XXXVI_4">IV</a>. The critical days, in which fevers are + supposed to terminate, have employed the attention of medical + philosophers from the days of Hippocrates to the present time. In + whatever part of a lunation a fever commences, which owes either its + whole cause to solar and lunar influence, or to this in conjunction with + other causes; it would seem, that the effect would be the greatest at the + full and new moon, as the tides rise highest at those times, and would be + the least at the quadratures; thus if a fever-fit should commence at the + new or full moon, occasioned by the solar and lunar attraction + diminishing some chemical affinity of the particles of blood, and thence + decreasing their stimulus on our sanguiferous system, as mentioned in + Sect. <a href="#sect_XXXII_6">XXXII. 6</a>. this effect will daily + decrease for the first seven days, and will then increase till about the + fourteenth day, and will again decrease till about the twenty-first day, + and increase again till the end of the lunation. If a fever-fit from the + above cause should commence on the seventh day after either lunation, the + reverse of the above circumstances would happen. Now it is probable, that + those fevers, whose crisis or terminations are influenced by lunations, + may begin at one or other of the above times, namely at the changes or + quadratures; though sufficient observations have not been made to + ascertain this circumstance. Hence I conclude, that the small-pox and + measles have their critical days, not governed by the times required for + certain chemical changes in the blood, which affect or alter the stimulus + of the contagious matter, but from the daily increasing or decreasing + effect of this lunar link of catenation, as explained in Section <a + href="#sect_XVII_3_3">XVII. 3. 3</a>. And as other fevers terminate most + frequently about the seventh, fourteenth, twenty-first, or about the end + of four weeks, when no medical assistance has disturbed their periods, I + conclude, that these crises, or terminations, are governed by periods of + the lunations; though we are still ignorant of their manner of + operation.</p> + + <p>In the distinct small-pox the vestiges of lunation are very apparent, + 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 maturation, and another quarter terminates the + complete absorption of a material now rendered inoffensive to the + constitution.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXXVII">XXXVII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF DIGESTION, SECRETION, NUTRITION.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXXVII_1">I</a>. <i>Crystals increase by the greater + attraction of their sides. Accretion by chemical precipitations, by + welding, by pressure, by agglutination.</i> <a + href="#sect_XXXVII_2">II</a>. <i>Hunger, digestion, why it cannot be + imitated out of the body. Lacteals absorb by animal selection or + appetency.</i> <a href="#sect_XXXVII_3">III</a>. <i>The glands and pores + absorb nutritious particles by animal selection. Organic particles of + Buffon. Nutrition applied at the time of elongation of fibres. Like + inflammation.</i> <a href="#sect_XXXVII_4">IV</a>. <i>It seems easier to + have preserved animals than to reproduce them. Old age and death from + inirritability. Three causes of this. Original fibres of the organs of + sense and muscles unchanged.</i> <a href="#sect_XXXVII_5">V</a>. <i>Art + of producing long life.</i></p> + +</blockquote> + + <p><a name="sect_XXXVII_1">I</a>. The larger crystals of saline bodies + may be conceived to arise from the combination of smaller crystals of the + same form, owing to the greater attractions of their sides than of their + angles. Thus if four cubes were floating in a fluid, whose friction or + resistance is nothing, it is certain the sides of these cubes would + attract each other stronger than their angles; and hence that these four + smaller cubes would so arrange themselves as to produce one larger + one.</p> + + <p>There are other means of chemical accretion, such as the depositions + of dissolved calcareous or siliceous particles, as are seen in the + formation of the stalactites of limestone in Derbyshire, or of calcedone + in Cornwall. Other means of adhesion are produced by heat and pressure, + as in the welding of iron-bars; and other means by simple pressure, as in + forcing two pieces of caoutchou, or elastic gum, to adhere; and lastly, + by the agglutination of a third substance penetrating the pores of the + other two, as in the agglutination of wood by means of animal gluten. + Though the ultimate particles of animal bodies are held together during + life, as well as after death, by their specific attraction of cohesion, + like all other matter; yet it does not appear, that their original + organization was produced by chemical laws, and their production and + increase must therefore only be looked for from the laws of + animation.</p> + + <p><a name="sect_XXXVII_2">II</a>. When the pain of hunger requires + relief, certain parts of the material world, which surround us, when + applied to our palates, excite into action the muscles of deglutition; + and the material is swallowed into the stomach. Here the new aliment + becomes mixed with certain animal fluids, and undergoes a chemical + process, termed digestion; which however chemistry has not yet learnt to + imitate out of the bodies of living animals or vegetables. This process + seems very similar to the saccharine process in the lobes of farinaceous + seeds, as of barley, when it begins to germinate; except that, along with + the sugar, oil and mucilage are also produced; which form the chyle of + animals, which is very similar to their milk.</p> + + <p>The reason, I imagine, why this chyle-making, or saccharine process, + has not yet been imitated by chemical operations, is owing to the + materials being in such a situation in respect to warmth, moisture, and + motion; that they will immediately change into the vinous or acetous + fermentation; except the new sugar be absorbed by the numerous lacteal or + lymphatic vessels, as soon as it is produced; which is not easy to + imitate in the laboratory.</p> + + <p>These lacteal vessels have mouths, which are irritated into action by + the stimulus of the fluid, which surrounds them; and by animal selection, + or appetency, they absorb such part of the fluid as is agreeable to their + palate; those parts, for instance, which are already converted into + chyle, before they have time to undergo another change by a vinous or + acetous fermentation. This animal absorption of fluid is almost visible + to the naked eye in the action of the puncta lacrymalia; which imbibe the + tears from the eye, and discharge them again into the nostrils.</p> + + <p><a name="sect_XXXVII_3">III</a>. The arteries constitute another + reservoir of a changeful fluid; from which, after its recent oxygenation + in the lungs, a further animal selection of various fluids is absorbed by + the numerous glands; these select their respective fluids from the blood, + which is perpetually undergoing a chemical change; but the selection by + these glands, like that of the lacteals, which open their mouths into the + digesting aliment in the stomach, is from animal appetency, not from + chemical affinity; secretion cannot therefore be imitated in the + laboratory, as it consists in a selection of part of a fluid during the + chemical change of that fluid.</p> + + <p>The mouths of the lacteals, and lymphatics, and the ultimate + terminations of the glands, are finer than can easily be conceived; yet + it is probable, that the pores, or interstices of the parts, or coats, + which constitute these ultimate vessels, may still have greater tenuity; + and that these pores from the above analogy must posses a similar power + of irritability, and absorb by their living energy the particles of fluid + adapted to their purposes, whether to replace the parts abraded or + dissolved, or to elongate and enlarge themselves. Not only every kind of + gland is thus endued with its peculiar appetency, and selects the + material agreeable to its taste from the blood, but every individual pore + acquires by animal selection the material, which it wants; and thus + nutrition seems to be performed in a manner so similar to secretion; that + they only differ in the one retaining, and the other parting again with + the particles, which they have selected from the blood.</p> + + <p>This way of accounting for nutrition from stimulus, and the consequent + animal selection of particles, is much more analogous to other phenomena + of the animal microcosm, than by having recourse to the microscopic + animalcula, or organic particles of Buffon, and Needham; which being + already compounded must themselves require nutritive particles to + continue their own existence. And must be liable to undergo a change by + our digestive or secretory organs; otherwise mankind would soon resemble + by their theory the animals, which they feed upon. He, who is nourished + by beef or venison, would in time become horned; and he, who feeds on + pork or bacon, would gain a nose proper for rooting into the earth, as + well as for the perception of odours.</p> + + <p>The whole animal system may be considered as consisting of the + extremities of the nerves, or of having been produced from them; if we + except perhaps the medullary part of the brain residing in the head and + spine, and in the trunks of the nerves. These extremities of the nerves + are either of those of locomotion, which are termed muscular fibres; or + of those of sensation, which constitute the immediate organs of sense, + and which have also their peculiar motions. Now as the fibres, which + constitute the bones and membranes, possessed originally sensation and + motion; and are liable again to possess them, when they become inflamed; + it follows, that those were, when first formed, appendages to the nerves + of sensation or locomotion, or were formed from them. And that hence all + these solid parts of the body, as they have originally consisted of + extremities of nerves, require an apposition of nutritive particles of a + similar kind, contrary to the opinion of Buffon and Needham above + recited.</p> + + <p>Lastly, as all these filaments have possessed, or do possess, the + power of contraction, and of consequent inertion or elongation; it seems + probable, that the nutritive particles are applied during their times of + elongation; when their original constituent particles are removed to a + greater distance from each other. For each muscular or sensual fibre may + be considered as a row or string of beads; which approach, when in + contraction, and recede during its rest or elongation; and our daily + experience shews us, that great action emaciates the system, and that it + is repaired during rest.</p> + + <p>Something like this is seen out of the body; for if a hair, or a + single untwisted fibre of flax or silk, be soaked in water; it becomes + longer and thicker by the water, which is absorbed into its pores. Now if + a hair could be supposed to be thus immersed in a solution of particles + similar to those, which compose it; one may imagine, that it might be + thus increased in weight and magnitude; as the particles of oak-bark + increase the substance of the hides of beasts in the process of making + leather. I mention these not as philosophic analogies, but as similes to + facilitate our ideas, how an accretion of parts may be effected by animal + appetences, or selections, in a manner somewhat similar to mechanical or + chemical attractions.</p> + + <p>If those new particles of matter, previously prepared by digestion and + sanguification, only supply the places of those, which have been abraded + by the actions of the system, it is properly termed nutrition. If they + are applied to the extremities of the nervous fibrils, or in such + quantity as to increase the length or crassitude of them, the body + becomes at the same time enlarged, and its growth is increased, as well + as its deficiences repaired.</p> + + <p>In this last case something more than a simple apposition or selection + of particles seems to be necessary; as many parts of the system during + its growth are caused to recede from those, with which they were before + in contact; as the ends of the bones, or cartilages, recede from each + other, as their growth advances: this process resembles inflammation, as + appears in ophthalmy, or in the production of new flesh in ulcers, where + old vessels are enlarged, and new ones produced; and like that is + attended with sensation. In this situation the vessels become distended + with blood, and acquire greater sensibility, and may thus be compared to + the erection of the penis, or of the nipples of the breasts of women; + while new particles become added at the same time; as in the process of + nutrition above described.</p> + + <p>When only the natural growth of the various parts of the body are + produced, a pleasurable sensation attends it, as in youth, and perhaps in + those, who are in the progress of becoming fat. When an unnatural growth + is the consequence, as in inflammatory diseases, a painful sensation + attends the enlargement of the system.</p> + + <p><a name="sect_XXXVII_4">IV</a>. This apposition of new parts, as the + old ones disappear, selected from the aliment we take, first enlarges and + strengthens our bodies for twenty years, for another twenty years it + keeps us in health and vigour, and adds strength and solidity to the + system; and then gradually ceases to nourish us properly, and for another + twenty years we gradually sink into decay, and finally cease to act, and + to exist.</p> + + <p>On considering this subject one should have imagined at first view, + that it might have been easier for nature to have supported her progeny + for ever in health and life, than to have perpetually reproduced them by + the wonderful and mysterious process of generation. But it seems our + bodies by long habit cease to obey the stimulus of the aliment, which + should support us. After we have acquired our height and solidity we make + no more new parts, and the system obeys the irritations, sensations, + volitions; and associations, with, less and less energy, till the whole + sinks into inaction.</p> + + <p>Three causes may conspire to render our nerves less excitable, which + have been already mentioned, 1. If a stimulus be greater than natural, it + produces too great an exertion of the stimulated organ, and in + consequence exhausts the spirit of animation; and the moving organ ceases + to act, even though the stimulus be continued. And though rest will + recruit this exhaustion, yet some degree of permanent injury remains, as + is evident after exposing the eyes long to too strong a light. 2. If + excitations weaker than natural be applied, so as not to excite the organ + into action, (as when small doses of aloe or rhubarb are exhibited,) they + may be gradually increased, without exciting the organ into action; which + will thus acquire a habit of disobedience to the stimulus; thus by + increasing the dose by degrees, great quantities of opium or wine may be + taken without intoxication. See Sect. <a href="#sect_XII_3_1">XII. 3. + 1</a>.</p> + + <p>3. Another mode, by which life is gradually undermined, is when + irritative motions continue to be produced in consequence of stimulus, + but are not succeeded by sensation; hence the stimulus of contagious + matter is not capable of producing fever a second time, because it is not + succeeded by sensation. See Sect. <a href="#sect_XII_3_6">XII. 3. 6</a>. + And hence, owing to the want of the general pleasurable sensation, which + ought to attend digestion and glandular secretion, an irksomeness of life + ensues; and, where this is in greater excess, the melancholy of old age + occurs, with torpor or debility.</p> + + <p>From hence I conclude, that it is probable that the fibrillæ, or + moving filaments at the extremities of the nerves of sense, and the + fibres which constitute the muscles (which are perhaps the only parts of + the system that are endued with contractile life) are not changed, as we + advance in years, like the other parts of the body; but only enlarged or + elongated with our growth; and in consequence they become less and less + excitable into action. Whence, instead of gradually changing the old + animal, the generation of a totally new one becomes necessary with + undiminished excitability; which many years will continue to acquire new + parts, or new solidity, and then losing its excitability in time, perish + like its parent.</p> + + <p><a name="sect_XXXVII_5">V</a>. From this idea the art of preserving + long health and life may be deduced; which must consist in using no + greater stimulus, whether of the quantity or kind of our food and drink, + or of external circumstances, such as heat, and exercise, and + wakefulness, than is sufficient to preserve us in vigour; and gradually, + as we grow old to increase the stimulus of our aliment, as the + irritability of our system increases.</p> + + <p>The debilitating effects ascribed by the poet M<font + class="sc">ARTIAL</font> to the excessive use of warm bathing in Italy, + may with equal propriety be applied to the warm rooms of England; which, + with the general excessive stimulus of spirituous or fermented liquors, + and in some instances of immoderate venery, contribute to shorten our + lives.</p> + + <div class="poem"> + <div class="stanza"> + <p><i>Balnea, vina, venus, corrumpunt corpora nostra</i>,</p> + <p><i>At faciunt vitam balnea, vina, venus!</i></p> + </div> + + <div class="stanza"> + <p>Wine, women, warmth, against our lives combine;</p> + <p>But what is life without warmth, women, wine!</p> + </div> + </div> + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXXVIII">XXXVIII</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF THE OXYGENATION OF THE BLOOD IN THE LUNGS, +AND IN THE PLACENTA.</p> + +<blockquote class="b1"> + + <p><a href="#sect_XXXVIII_1">I</a>. <i>Blood absorbs oxygene from the + air, whence phosphoric acid changes its colour, gives out heat, and some + phlogistic material, and acquires an ethereal spirit, which is dissipated + in fibrous motion.</i> <a href="#sect_XXXVIII_2">II</a>. <i>The placenta + is a pulmonary organ like the gills of fish. Oxygenation of the blood + from air, from water, by lungs, by gills, by the placenta; necessity of + this oxygenation to quadrupeds, to fish, to the fœtus in utero. + Placental vessels inserted into the arteries of the mother. Use of + cotyledons in cows. Why quadrupeds have not sanguiferous lochia. + Oxygenation of the chick in the egg, of feeds.</i> <a + href="#sect_XXXVIII_3">III</a>. <i>The liquor amnii is not + excrementitious. It is nutritious. It is found in the esophagus and + stomach, and forms the meconium. Monstrous births without heads. Question + of Dr. Harvey.</i></p> + +</blockquote> + + <p><a name="sect_XXXVIII_1">I</a>. From the recent discoveries of many + ingenious philosophers it appears, that during respiration the blood + imbibes the vital part of the air, called oxygene, through the membranes + of the lungs; and that hence respiration may be aptly compared to a slow + combustion. As in combustion the oxygene of the atmosphere unites with + some phlogistic or inflammable body, and forms an acid (as in the + production of vitriolic acid from sulphur, or carbonic acid from + charcoal,) giving out at the same time a quantity of the matter of heat; + so in respiration the oxygene of the air unites with the phlogistic part + of the blood, and probably produces phosphoric or animal acid, changing + the colour of the blood from a dark to a bright red; and probably some of + the matter of heat is at the same time given out according to the theory + of Dr. Crawford. But as the evolution of heat attends almost all chemical + combinations, it is probable, that it also attends the secretions of the + various fluids from the blood; and that the constant combinations or + productions of new fluids by means of the glands constitute the more + general source of animal heat; this seems evinced by the universal + evolution of the matter of heat in the blush of shame or of anger; in + which at the same time an increased secretion of the perspirable matter + occurs; and the partial evolution of it from topical inflammations, as in + gout or rheumatism, in which there is a secretion of new + blood-vessels.</p> + + <p>Some medical philosophers have ascribed the heat of animal bodies to + the friction of the particles of the blood against the sides of the + vessels. But no perceptible heat has ever been produced by the agitation + of water, or oil, or quicksilver, or other fluids; except those fluids + have undergone at the same time some chemical change, as in agitating + milk or wine, till they become sour.</p> + + <p>Besides the supposed production of phosphoric acid, and change of + colour of the blood, and the production of carbonic acid, there would + appear to be something of a more subtile nature perpetually acquired from + the atmosphere; which is too fine to be long contained in animal vessels, + and therefore requires perpetual renovation; and without which life + cannot continue longer than a minute or two; this ethereal fluid is + probably secreted from the blood by the brain, and perpetually dissipated + in the actions of the muscles and organs of sense.</p> + + <p>That the blood acquires something from the air, which is immediately + necessary to life, appears from an experiment of Dr. Hare (Philos. + Transact. abridged, Vol. III. p. 239.) who found, "that birds, mice, + &c. would live as long again in a vessel, where he had crowded in + double the quantity of air by a condensing engine, than they did when + confined in air of the common density." Whereas if some kind of + deleterious vapour only was exhaled from the blood in respiration; the + air, when condensed into half its compass, could not be supposed to + receive so much of it.</p> + + <p><a name="sect_XXXVIII_2">II</a>. Sir Edward Hulse, a physician of + reputation at the beginning of the present century, was of opinion, that + the placenta was a respiratory organ, like the gills of fish; and not an + organ to supply nutriment to the fœtus; as mentioned in Derham's + Physico-theology. Many other physicians seem to have espoused the same + opinion, as noticed by Haller. Elem. Physiologiæ, T. 1. Dr. Gipson + published a defence of this theory in the Medical Essays of Edinburgh, + Vol. I. and II. which doctrine is there controverted at large by the late + Alexander Monro; and since that time the general opinion has been, that + the placenta is an organ of nutrition only, owing perhaps rather to the + authority of so great a name, than to the validity of the arguments + adduced in its support. The subject has lately been resumed by Dr. James + Jeffray, and by Dr. Forester French, in their inaugural dissertations at + Edinburgh and at Cambridge; who have defended the contrary opinion in an + able and ingenious manner; and from whose Theses I have extracted many of + the following remarks.</p> + + <p>First, by the late discoveries of Dr. Priestley, M. Lavoisier, and + other philosophers, it appears, that the basis of atmospherical air, + called oxygene, is received by the blood through the membranes of the + lungs; and that by this addition the colour of the blood is changed from + a dark to a light red. Secondly, that water possesses oxygene also as a + part of its composition, and contains air likewise in its pores; whence + the blood of fish receives oxygene from the water, or from the air it + contains, by means of their gills, in the same manner as the blood is + oxygenated in the lungs of air-breathing animals; it changes its colour + at the same time from a dark to a light red in the vessels of their + gills, which constitute a pulmonary organ adapted to the medium in which + they live. Thirdly, that the placenta consists of arteries carrying the + blood to its extremities, and a vein bringing it back, resembling exactly + in structure the lungs and gills above mentioned; and that the blood + changes its colour from a dark to a light red in passing through these + vessels.</p> + + <p>This analogy between the lungs and gills of animals, and the placenta + of the fetus, extends through a great variety of other circumstances; + thus air-breathing creatures and fish can live but a few minutes without + air or water; or when they are confined in such air or water, as has been + spoiled by their own respiration; the same happens to the fetus, which, + as soon as the placenta is separated from the uterus, must either expand + its lungs, and receive air, or die. Hence from the structure, as well as + the use of the placenta, it appears to be a respiratory organ, like the + gills of fish, by which the blood in the fetus becomes oxygenated.</p> + + <p>From the terminations of the placental vessels not being observed to + bleed after being torn from the uterus, while those of the uterus effuse + a great quantity of florid arterial blood, the terminations of the + placental vessels would seem to be inserted into the arterial ones of the + mother; and to receive oxygenation from the passing currents of her blood + through their coats or membranes; which oxygenation is proved by the + change of the colour of the blood from dark to light red in its passage + from the placental arteries to the placental vein.</p> + + <p>The curious structure of the cavities or lacunæ of the placenta, + demonstrated by Mr. J. Hunter, explain this circumstance. That ingenious + philosopher has shewn, that there are numerous cavities of lacunæ formed + on that side of the placenta, which is in contact with the uterus; those + cavities or cells are filled with blood from the maternal arteries, which + open into them; which blood is again taken up by the maternal veins, and + is thus perpetually changed. While the terminations of the placental + arteries and veins are spread in fine reticulation on the sides of these + cells. And thus, as the growing fetus requires greater oxygenation, an + apparatus is produced resembling exactly the air-cells of the lungs.</p> + + <p>In cows, and other ruminating animals, the internal surface of the + uterus is unequal like hollow cups, which have been called cotyledons; + and into these cavities the prominencies of the numerous placentas, with + which the fetus of those animals is furnished, are inserted, and strictly + adhere; though they may be extracted without effusion of blood. These + inequalities of the uterus, and the numerous placentas in consequence, + seem to be designed for the purpose of expanding a greater surface for + the terminations of the placental vessels for the purpose of receiving + oxygenation from the uterine ones; as the progeny of this class of + animals are more completely formed before their nativity, than that of + the carnivorous classes, and must thence in the latter weeks of pregnancy + require greater oxygenation. Thus calves and lambs can walk about in a + few minutes after their birth; while puppies and kittens remain many days + without opening their eyes. And though on the separation of the + cotyledons of ruminating animals no blood is effused, yet this is owing + clearly to the greater power of contraction of their uterine lacunæ or + alveoli. See Medical Essays, Vol. V. page 144. And from the same cause + they are not liable to a sanguiferous menstruation.</p> + + <p>The necessity of the oxygenation of the blood in the fetus is farther + illustrated by the analogy of the chick in the egg; which appears to have + its blood oxygenated at the extremities of the vessels surrounding the + yolk; which are spread on the air-bag at the broad end of the egg, and + may absorb oxygene through that moist membrane from the air confined + behind it; and which is shewn by experiments in the exhausted receiver to + be changeable though the shell.</p> + + <p>This analogy may even be extended to the growing seeds of vegetables; + which were shewn by Mr. Scheele to require a renovation of the air over + the water, in which they were confined. Many vegetable seeds are + surrounded with air in their pods or receptacles, as peas, the fruit of + staphylea, and lichnis vesicaria; but it is probable, that those seeds, + after they are shed, as well as the spawn of fish, by the situation of + the former on or near the moist and aerated surface of the earth, and of + the latter in the ever-changing and ventilated water, may not be in need + of an apparatus for the oxygenation of their first blood, before the + leaves of one, and the gills of the other, are produced for this + purpose.</p> + + <p><a name="sect_XXXVIII_3">III</a>. <a name="sect_XXXVIII_3_1">1</a>. + There are many arguments, besides the strict analogy between the liquor + amnii and the albumen ovi, which shew the former to be a nutritive fluid; + and that the fetus in the latter months of pregnancy takes it into its + stomach; and that in consequence the placenta is produced for some other + important purpose.</p> + + <p>First, that the liquor amnii is not an excrementitious fluid is + evinced, because it is found in greater quantity, when the fetus is + young, decreasing after a certain period till birth. Haller asserts, + "that in some animals but a small quantity of this fluid remains at the + birth. In the eggs of hens it is consumed on the eighteenth day, so that + at the exclusion of the chick scarcely any remains. In rabbits before + birth there is none." Elem. Physiol. Had this been an excrementitious + fluid, the contrary would probably have occurred. Secondly, the skin of + the fetus is covered with a whitish crust or pellicle, which would seem + to preclude any idea of the liquor amnii being produced by any exsudation + of perspirable matter. And it cannot consist of urine, because in brute + animals the urachus passes from the bladder to the alantois for the + express purpose of carrying off that fluid; which however in the human + fetus seems to be retained in the distended bladder, as the feces are + accumulated in the bowels of all animals.</p> + + <p><a name="sect_XXXVIII_3_2">2</a>. The nutritious quality of the + liquid, which surrounds the fetus, appears from the following + considerations. 1. It is coagulable by heat, by nitrous acid, and by + spirit of wine, like milk, serum of blood, and other fluids, which daily + experience evinces to be nutritious. 2. It has a saltish taste according + to the accurate Baron Haller, not unlike the whey of milk, which it even + resembles in smell. 3. The white of the egg which constitutes the food of + the chick, is shewn to be nutritious by our daily experience; besides the + experiment of its nutritious effects mentioned by Dr. Fordyce in his late + Treatise on Digestion, p. 178; who adds, that it much resembles the + essential parts of the serum of blood.</p> + + <p><a name="sect_XXXVIII_3_3">3</a>. A fluid similar to the fluid, with + which the fetus is surrounded, except what little change may be produced + by a beginning digestion, is found in the stomach of the fetus; and the + white of the egg is found, in the same manner in the stomach of the + chick.</p> + + <p>Numerous hairs, similar to those of its skin, are perpetually found + among the contents of the stomach in new-born calves; which must + therefore have licked themselves before their nativity. Blasii Anatom. + See Sect. <a href="#sect_XVI_2">XVI. 2</a>. on Instinct.</p> + + <p>The chick in the egg is seen gently to move in its surrounding fluid, + and to open and shut its mouth alternately. The same has been observed in + puppies. Haller's El. Phys. I. 8. p. 201.</p> + + <p>A column of ice has been seen to reach down the œsophagus from + the mouth to the stomach in a frozen fetus; and this ice was the liquor + amnii frozen.</p> + + <p>The meconium, or first fæces, in the bowels of new-born infants + evince, that something has been digested; and what could this be but the + liquor amnii together with the recrements of the gastric juice and gall, + which were necessary for its digestion?</p> + + <p>There have been recorded some monstrous births of animals without + heads, and consequently without mouths, which seem to have been delivered + on doubtful authority, or from inaccurate observation. There are two of + such monstrous productions however better attested; one of a human fetus, + mentioned by Gipson in the Scots Medical Essays; which having the gula + impervious was furnished with an aperture into the wind-pipe, which + communicated below into the gullet; by means of which the liquor amnii + might be taken into the stomach before nativity without danger of + suffocation, while the fetus had no occasion to breathe. The other + monstrous fetus is described by Vander Wiel, who asserts, that he saw a + monstrous lamb, which had no mouth; but instead of it was furnished with + an opening in the lower part of the neck into the stomach. Both these + instances evidently favour the doctrine of the fetus being nourished by + the mouth; as otherwise there had been no necessity for new or unnatural + apertures into the stomach, when the natural ones were deficient?</p> + + <p>From these facts and observations we may safely infer, that the fetus + in the womb is nourished by the fluid which surrounds it; which during + the first period of gestation is absorbed by the naked lacteals; and is + afterwards swallowed into the stomach and bowels, when these organs are + perfected; and lastly that the placenta is an organ for the purpose of + giving due oxygenation to the blood of the fetus; which is more + necessary, or at least more frequently necessary, than even the supply of + food.</p> + + <p>The question of the great Harvey becomes thus easily answered. "Why is + not the fetus in the womb suffocated for want of air, when it remains + there even to the tenth month without respiration: yet if it be born in + the seventh or eighth month, and has once respired, it becomes + immediately suffocated for want of air, if its respiration be + obstructed?"</p> + + <p>For further information on this subject, the reader is referred to the + Tentamen Medicum of Dr. Jeffray, printed at Edinburgh in 1786. And it is + hoped that Dr. French will some time give his theses on this subject to + the public.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XXXIX">XXXIX</a>.</h3> + +<p class="center" style="margin-top: 2em;">OF GENERATION.</p> + + <div class="contents"> + <div class="stanza"> + <p>Felix, qui causas altà caligine mersas</p> + <p>Pandit, et evolvit tenuissima vincula rerum.</p> + </div> + </div> +<blockquote class="b1"> + + <p><a href="#sect_XXXIX_1">I</a>. <i>Habits of acting and feeling of + individuals attend the soul into a future life, and attend the new + embryon at the time of its production. The new speck of entity absorbs + nutriment, and receives oxygene. Spreads the terminations of its vessels + on cells, which communicate with the arteries of the uterus; sometimes + with those of the peritoneum. Afterwards it swallows the liquor amnii, + which it produces by its irritation from the uterus, or peritoneum. Like + insects in the heads of calves and sheep. Why the white of egg is of two + consistencies. Why nothing is found in quadrupeds similar to the yolk, + nor in most vegetable seeds.</i> <a href="#sect_XXXIX_2">II</a>. <a + href="#sect_XXXIX_2_1">1</a>. <i>Eggs of frogs and fish impregnated out + of their bodies. Eggs of fowls which are not fecundated, contain only the + nutriment for the embryon. The embryon is produced by the male, and the + nutriment by the female. Animalcula in semine. Profusion of nature's + births.</i> <a href="#sect_XXXIX_2_2">2</a>. <i>Vegetables viviparous. + Buds and bulbs have each a father but no mother. Vessels of the leaf and + bud inosculate. The paternal offspring exactly resembles the parent.</i> + <a href="#sect_XXXIX_2_3">3</a>. <i>Insects impregnated for six + generations. Polypus branches like buds. Creeping roots. Viviparous + flowers. Tænia, volvox. Eve from Adam's rib. Semen not a stimulus to the + egg.</i> <a href="#sect_XXXIX_3">III</a>. <a + href="#sect_XXXIX_3_1">1</a>. <i>Embryons not originally created within + other embryons. Organized matter is not so minute.</i> <a + href="#sect_XXXIX_3_2">2</a>. <i>All the parts of the embryon are not + formed in the male parent. Crabs produce their legs, worms produce their + heads and tails. In wens, cancers, and inflammations, new vessels are + formed. Mules partake of the forms of both parents. Hair and nails grow + by elongation, not by distention.</i> <a href="#sect_XXXIX_3_3">3</a>. + <i>Organic particles of Buffon.</i> <a href="#sect_XXXIX_4">IV</a>. <a + href="#sect_XXXIX_4_1">1</a>. <i>Rudiment of the embryon a simple living + filament, becomes a living ring, and then a living tube.</i> <a + href="#sect_XXXIX_4_2">2</a>. <i>It acquires irritabilities, and + sensibilities with new organizations, as in wounded snails, polypi, + moths, gnats, tadpoles. Hence new parts are acquired by addition not by + distention.</i> <a href="#sect_XXXIX_4_3">3</a>. <i>All parts of the body + grow if not confined.</i> <a href="#sect_XXXIX_4_4">4</a>. <i>Fetuses + deficient at their extremities, or have a duplicature of parts. Monstrous + births. Double parts of vegetables.</i> <a href="#sect_XXXIX_4_5">5</a>. + <i>Mules cannot be formed by distention of the seminal ens.</i> <a + href="#sect_XXXIX_4_6">6</a>. <i>Families of animals from a mixture of + their orders. Mules imperfect.</i> <a href="#sect_XXXIX_4_7">7</a>. + <i>Animal appetency like chemical affinity. Vis fabricatrix and + medicatrix of nature.</i> <a href="#sect_XXXIX_4_8">8</a>. <i>The changes + of animals before and after nativity. Similarity of their structure. + Changes in them from lust, hunger, and danger. All warm-blooded animals + derived from one living filament. Cold-blooded animals, insects, worms, + vegetables, derived also from one living filament. Male animals have + teats. Male pigeon gives milk. The world itself generated. The cause of + causes. A state of probation and responsibility.</i> <a + href="#sect_XXXIX_5">V</a>. <a href="#sect_XXXIX_5_1">1</a>. <i>Efficient + cause of the colours of birds eggs, and of hair and feathers, which + become white in snowy countries. Imagination of the female colours the + egg. Ideas or motions of the retina imitated by the extremities of the + nerves of touch, or rete mucosum.</i> <a href="#sect_XXXIX_5_2">2</a>. + <i>Nutriment supplied by the female of three kinds. Her imagination can + only affect the first kind. Mules how produced, and mulattoes. Organs of + reproduction why deficient in mules. Eggs with double yolks.</i> <a + href="#sect_XXXIX_6">VI</a>. <a href="#sect_XXXIX_6_1">1</a>. <i>Various + secretions produced by the extremities of the vessels, as in the glands. + Contagious matter. Many glands affected by pleasurable ideas, as those + which secrete the semen.</i> <a href="#sect_XXXIX_6_2">2</a>. <i>Snails + and worms are hermaphrodite, yet cannot impregnate themselves. Final + cause of this.</i> <a href="#sect_XXXIX_6_3">3</a>. <i>The imagination of + the male forms the sex. Ideas, or motions of the nerves of vision or of + touch, are imitated by the ultimate extremities of the glands of the + testes, which mark the sex. This effect of the imagination belongs only + to the male. The sex of the embryon is not owing to accident.</i> <a + href="#sect_XXXIX_6_4">4</a>. <i>Causes of the changes in animals from + imagination as in monsters. From the male. From the female.</i> <a + href="#sect_XXXIX_6_5">5</a>. <i>Miscarriages from fear.</i> <a + href="#sect_XXXIX_6_6">6</a>. <i>Power of the imagination of the male + over the colour, form, and sex of the progeny. An instance of.</i> <a + href="#sect_XXXIX_6_7">7</a>. <i>Act of generation accompanied with ideas + of the male or female form. Art of begetting beautiful children of either + sex.</i> <a href="#sect_XXXIX_7">VII</a>. <i>Recapitulation.</i> <a + href="#sect_XXXIX_8">VIII</a>. <i>Conclusion. Of cause and effect. The + atomic philosophy leads to a first cause.</i></p> + +</blockquote> + + <p><a name="sect_XXXIX_1">I</a>. The ingenious Dr. Hartley in his work on + man, and some other philosophers, have been of opinion, that our immortal + part acquires during this life certain habits of action or of sentiment, + which become for ever indissoluble, continuing after death in a future + state of existence; and add, that if these habits are of the malevolent + kind, they must render the possessor miserable even in heaven. I would + apply this ingenious idea to the generation or production of the embryon, + or new animal, which partakes so much of the form and propensities of the + parent.</p> + + <p>Owing to the imperfection of language the offspring is termed a + <i>new</i> animal, but is in truth a branch or elongation of the parent; + since a part of the embryon-animal is, or was, a part of the parent; and + therefore in strict language it cannot be said to be entirely <i>new</i> + at the time of its production; and therefore it may retain some of the + habits of the parent-system.</p> + + <p>At the earliest period of its existence the embryon, as secreted from + the blood of the male, would seem to consist of a living filament with + certain capabilities of irritation, sensation, volition, and association; + and also with some acquired habits or propensities peculiar to the + parent: the former of these are in common with other animals; the latter + seem to distinguish or produce the kind of animal, whether man or + quadruped, with the similarity of feature or form to the parent. It is + difficult to be conceived, that a living entity can be separated or + produced from the blood by the action of a gland; and which shall + afterwards become an animal similar to that in whose vessels it is + formed; even though we should suppose with some modern theorists, that + the blood is alive; yet every other hypothesis concerning generation + rests on principles still more difficult to our comprehension.</p> + + <p>At the time of procreation this speck of entity is received into an + appropriated nidus, in which it must acquire two circumstances necessary + to its life and growth; one of these is food or sustenance, which is to + be received by the absorbent mouths of its vessels; and the other is that + part of atmospherical air, or of water, which by the new chemistry is + termed oxygene, and which affects the blood by passing through the coats + of the vessels which contain it. The fluid surrounding the embryon in its + new habitation, which is called liquor amnii, supplies it with + nourishment; and as some air cannot but be introduced into the uterus + along with a new embryon, it would seem that this same fluid would for a + short time, suppose for a few hours, supply likewise a sufficient + quantity of the oxygene for its immediate existence.</p> + + <p>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 stigmas + of the flower may have food of a more oxygenated kind than the common + vegetable sap-juice.</p> + + <p>On the introduction of this primordium of entity into the uterus the + irritation of the liquor amnii, which surrounds it, excites the absorbent + mouths of the new vessels into action; they drink up a part of it, and a + pleasurable sensation accompanies this new action; at the same time the + chemical affinity of the oxygene acts through the vessels of the + rubescent blood; and a previous want, or disagreeable sensation, is + relieved by this process.</p> + + <p>As the want of this oxygenation of the blood is perpetual, (as appears + from the incessant necessity of breathing by lungs or gills,) the vessels + become extended by the efforts of pain or desire to seek this necessary + object of oxygenation, and to remove the disagreeable sensation, which + that want occasions. At the same time new particles of matter are + absorbed, or applied to these extended vessels, and they become + permanently elongated, as the fluid in contact with them soon loses the + oxygenous part, which it at first possessed, which was owing to the + introduction of air along with the embryon. These new blood-vessels + approach the sides of the uterus, and penetrate with their fine + terminations into the vessels of the mother; or adhere to them, acquiring + oxygene through their coats from the passing currents of the arterial + blood of the mother. See Sect. <a href="#sect_XXXVIII_2">XXXVIII. + 2</a>.</p> + + <p>This attachment of the placental vessels to the internal side of the + uterus by their own proper efforts appears further illustrated by the + many instances of extra-uterine fetuses, which have thus attached or + inserted their vessels into the peritoneum; or on the viscera, exactly in + the same manner as they naturally insert or attach them to the + uterus.</p> + + <p>The absorbent vessels of the embryon continue to drink up nourishment + from the fluid in which they swim, or liquor amnii; and which at first + needs no previous digestive preparation; but which, when the whole + apparatus of digestion becomes complete, is swallowed by the mouth into + the stomach, and being mixed with saliva, gastric juice, bile, pancreatic + juice, and mucus of the intestines, becomes digested, and leaves a + recrement, which produces the first feces of the infant, called + meconium.</p> + + <p>The liquor amnii is secreted into the uterus, as the fetus requires + it, and may probably be produced by the irritation of the fetus as an + extraneous body; since a similar fluid is acquired from the peritoneum in + cases of extra-uterine gestation. The young caterpillars of the gadfly + placed in the skins of cows, and the young of the ichneumon-fly placed in + the backs of the caterpillars on cabbages, seem to produce their + nourishment by their irritating the sides of their nidus. A vegetable + secretion and concretion is thus produced on oak-leaves by the + gall-insect, and by the cynips in the bedeguar of the rose; and by the + young grasshopper on many plants, by which the animal surrounds itself + with froth. But in no circumstance is extra-uterine gestation so exactly + resembled as by the eggs of a fly, which are deposited in the frontal + sinus of sheep and calves. These eggs float in some ounces of fluid + collected in a thin pellicle or hydatide. This bag of fluid compresses + the optic nerve on one side, by which the vision being less distinct in + that eye, the animal turns in perpetual circles towards the side + affected, in order to get a more accurate view of objects; for the same + reason as in squinting the affected eye is turned away from the object + contemplated. Sheep in the warm months keep their noses close to the + ground to prevent this fly from so readily getting into their + nostrils.</p> + + <p>The liquor amnii is secreted into the womb as it is required, not only + in respect to quantity, but, as the digestive powers of the fetus become + formed, this fluid becomes of a different consistence and quality, till + it is exchanged for milk after nativity. Haller. Physiol. V. 1. In the + egg the white part, which is analogous to the liquor amnii of quadrupeds, + consists of two distinct parts; one of which is more viscid, and probably + more difficult of digestion, and more nutritive than the other; and this + latter is used in the last week of incubation. The yolk of the egg is a + still stronger or more nutritive fluid, which is drawn up into the bowels + of the chick just at its exclusion from the shell, and serves it for + nourishment for a day or two, till it is able to digest, and has learnt + to choose the harder seeds or grains, which are to afford it sustenance. + 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.</p> + + <p>The yolk therefore is not necessary to the spawn of fish, the eggs of + insects, or for the seeds of vegetables; as their embryons have probably + their food presented to them as soon as they are excluded from their + shells, or have extended their roots. Whence it happens that some insects + produce a living progeny in the spring and summer, and eggs in the + autumn; and some vegetables have living roots or buds produced in the + place of seeds, as the polygonum viviparum, and magical onions. See + Botanic Garden, p. 11. art. anthoxanthum.</p> + + <p>There seems however to be a reservoir of nutriment prepared for some + seeds besides their cotyledons or seed-leaves, which may be supposed in + some measure analogous to the yolk of the egg. Such are the saccharine + juices of apples, grapes and other fruits, which supply nutrition to the + seeds after they fall on the ground. And such is the milky juice in the + centre of the cocoa-nut, and part of the kernel of it; the same I suppose + of all other monocotyledon seeds, as of the palms, grasses, and + lilies.</p> + + <p><a name="sect_XXXIX_2">II</a>. <a name="sect_XXXIX_2_1">1</a>. The + process of generation is still involved in impenetrable obscurity, + conjectures may nevertheless be formed concerning some of its + circumstances. First, the eggs of fish and frogs are impregnated, after + they leave the body of the female; because they are deposited in a fluid, + and are not therefore covered with a hard shell. It is however + remarkable, that neither frogs nor fish will part with their spawn + without the presence of the male; on which account female carp and + gold-fish in small ponds, where there are no males, frequently die from + the distention of their growing spawn. 2. The eggs of fowls, which are + laid without being impregnated, are seen to contain only the yolk and + white, which are evidently the food or sustenance for the future chick. + 3. As the cicatricula of these eggs is given by the cock, and is + evidently the rudiment of the new animal; we may conclude, that the + embryon is produced by the male, and the proper food and nidus by the + female. For if the female be supposed to form an equal part of the + embryon, why should she form the whole of the apparatus for nutriment and + for oxygenation? the male in many animals is larger, stronger, and + digests more food than the female, and therefore should contribute as + much or more towards the reproduction of the species; but if he + contributes only half the embryon and none of the apparatus for + sustenance and oxygenation, the division is unequal; the strength of the + male, and his consumption of food are too great for the effect, compared + with that of the female, which is contrary to the usual course of + nature.</p> + + <p>In objection to this theory of generation it may be said, if the + animalcula in femine, as seen by the microscope, be all of them rudiments + of homunculi, when but one of them can find a nidus, what a waste nature + has made of her productions? I do not assert that these moving particles, + visible by the microscope, are homunciones; perhaps they may be the + creatures of stagnation or putridity, or perhaps no creatures at all; but + if they are supposed to be rudiments of homunculi, or embryons, such a + profusion of them corresponds with the general efforts of nature to + provide for the continuance of her species of animals. Every individual + tree produces innumerable seeds, and every individual fish innumerable + spawn, in such inconceivable abundance as would in a short space of time + crowd the earth and ocean with inhabitants; and these are much more + perfect animals than the animalcula in femine can be supposed to be, and + perish in uncounted millions. This argument only shews, that the + productions of nature are governed by general laws; and that by a wise + superfluity of provision she has ensured their continuance.</p> + + <p><a name="sect_XXXIX_2_2">2</a>. That the embryon is secreted or + produced by the male, and not by the conjunction of fluids from both male + and female, appears from the analogy of vegetable seeds. In the large + flowers, as the tulip, there is no similarity of apparatus between the + anthers and the stigma: the seed is produced according to the + observations of Spallanzani long before the flowers open, and in + consequence long before it can be impregnated, like the egg in the + pullet. And after the prolific dust is shed on the stigma, the seed + becomes coagulated in one point first, like the cicatricula of the + impregnated egg. See Botanic Garden, Part I. additional note 38. Now in + these simple products of nature, if the female contributed to produce the + new embryon equally with the male, there would probably have been some + visible similarity of parts for this purpose, besides those necessary for + the nidus and sustenance of the new progeny. Besides in many flowers the + males are more numerous than the females, or than the separate uterine + cells in their germs, which would shew, that the office of the male was + at least as important as that of the female; whereas if the female, + besides producing the egg or seed, was to produce an equal part of the + embryon, the office of reproduction would be unequally divided between + them.</p> + + <p>Add to this, that in the most simple kind of vegetable reproduction, I + mean the buds of trees, which are their viviparous offspring, the leaf is + evidently the parent of the bud, which rises in its bosom, according to + the observation of Linnaeus. This leaf consists of absorbent vessels, and + pulmonary ones, to obtain its nutriment, and to impregnate it with + oxygene. This simple piece of living organization is also furnished with + a power of reproduction; and as the new offspring is thus supported + adhering to its father, it needs no mother to supply it with a nidus, and + nutriment, and oxygenation; and hence no female leaf has existence.</p> + + <p>I conceive that the vessels between the bud and the leaf communicate + or inosculate; and that the bud is thus served with vegetable blood, that + is, with both nutriment and oxygenation, till the death of the + parent-leaf in autumn. And in this respect it differs from the fetus of + viviparous animals. Secondly, that then the bark-vessels belonging to the + dead-leaf, and in which I suppose a kind of manna to have been deposited, + become now the placental vessels, if they may be so called, of the new + bud. From the vernal sap thus produced of one sugar-maple-tree in + New-York and in Pennsylvania, five or six pounds of good sugar may be + made annually without destroying the tree. Account of maple-sugar by B. + Rushes. London, Phillips. (See Botanic Garden, Part I. additional note on + vegetable placentation.)</p> + + <p>These vessels, when the warmth of the vernal sun hatches the young + bud, serve it with a saccharine nutriment, till it acquires leaves of its + own, and shoots a new system of absorbents down the bark and root of the + tree, just as the farinaceous or oily matter in seeds, and the saccharine + matter in fruits, serve their embryons with nutriment, till they acquire + leaves and roots. This analogy is as forceable in so obscure a subject, + as it is curious, and may in large buds, as of the horse-chesnut, be + almost seen by the naked eye; if with a penknife the remaining rudiment + of the last year's leaf, and of the new bud in its bosom, be cut away + slice by slice. The seven ribs of the last year's leaf will be seen to + have arisen from the pith in seven distinct 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 without the assistance of a mother. A + similar process may be seen on dissecting a tulip-root in winter; the + leaves, which inclosed the last year's flower-stalk, were not necessary + for the flower; but each of these was the father of a new bud, which may + be now found at its base; and which, as it adheres to the parent, + required no mother.</p> + + <p>This paternal offspring of vegetables, I mean their buds and bulbs, is + attended with a very curious circumstance; and that is, that they exactly + resemble their parents, as is observable in grafting fruit-trees, and in + propagating flower-roots; whereas the seminal offspring of plants, being + supplied with nutriment by the mother, is liable to perpetual variation. + Thus also in the vegetable class dioicia, 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 similar + to themselves; and the buds of the female trees produce either female + flowers, or other buds similar to themselves; whereas the seeds of these + trees produce either male or female plants. From this analogy of the + production of vegetable buds without a mother, I contend that the mother + does not contribute to the formation of the living ens in animal + generation, but is necessary only for supplying its nutriment and + oxygenation.</p> + + <p>There is another vegetable fact published by M. Koelreuter, which he + calls "a complete metamorphosis of one natural species of plants into + another," which shews, that in seeds as well as in buds, the embryon + proceeds from the male parent, though the form of the subsequent mature + plant is in part dependant on the female. M. Koelreuter impregnated a + stigma of the nicotiana rustica with the farina of the nicotiana + paniculata, and obtained prolific seeds from it. With the plants which + sprung from these seeds, 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 impregnate them for many + generations with the farina of the nicotiana paniculata, and they became + more and more like the male parent, till he at length obtained six plants + in every respect perfectly similar to the nicotiana paniculata; and in no + respect resembling their female parent the nicotiana rustica. + <i>Blumenbach</i> on Generation.</p> + + <p><a name="sect_XXXIX_2_3">3</a>. It is probable that the insects, which + are said to require but one impregnation for six generations, as the + aphis (see Amenit. Academ.) produce their progeny in the manner above + described, that is, without a mother, and not without a father; and thus + experience a lucina sine concubitu. Those who have attended to the habits + of the polypus, which is found in the stagnant water of our ditches in + July, affirm, that the young ones branch out from the side of the parent + like the buds of trees, and after a time separate themselves from them. + This is so analogous to the manner in which the buds of trees appear to + be produced, that these polypi may be considered as all male animals, + producing embryons, which require no mother to supply them with a nidus, + or with nutriment, and oxygenation.</p> + + <p>This lateral or lineal generation of plants, not only obtains in the + buds of trees, which continue to adhere to them, but is beautifully seen + in the wires of knot-grass, polygonum aviculare, and in those of + strawberries, fragaria vesca. In these an elongated 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 consequence needs no maternal apparatus for these + purposes. In viviparous flowers, as those of allium magicum, and + polygonum viviparum, the anthers and the stigmas become effete and + perish; and the lateral or paternal offspring succeeds instead of seeds, + which adhere till they are sufficiently mature, and then fall upon the + ground, and take root like other bulbs.</p> + + <p>The lateral production of plants by wires, while each new plant is + thus chained to its parent, and continues to put forth another and + another, as the wire creeps onward on the ground, is exactly resembled by + the tape-worm, or tænia, so often found in the bowels, stretching itself + in a chain quite from the stomach to the rectum. Linnæus asserts, "that + it grows old at one extremity, while it continues to generate young ones + at the other, proceeding ad infinitum, like a root of grass. The separate + joints are called gourd-worms, and propagate new joints like the parent + without end, each joint being furnished with its proper mouth, and organs + of digestion." Systema naturæ. Vermes tenia. In this animal there + evidently appears a power of reproduction without any maternal apparatus + for the purpose of supplying nutriment and oxygenation to the embryon, as + it remains attached to its father till its maturity. The volvox globator, + which is a transparent animal, is said by Linnæus to bear within it sons + and grand-sons to the fifth generation. These are probably living + fetuses, produced by the father, of different degrees of maturity, to be + detruded at different periods of time, like the unimpregnated eggs of + various sizes, which are found in poultry; and as they are produced + without any known copulation, contribute to evince, that the living + embryon in other orders of animals is formed by the male-parent, and not + by the mother, as one parent has the power to produce it.</p> + + <p>This idea of the reproduction of animals from a single living filament + of their fathers, appears to have been shadowed or allegorized in the + curious account in sacred writ of the formation of Eve from a rib of + Adam.</p> + + <p>From all these analogies I conclude, that the embryon is produced + solely by the male, and that the female supplies it with a proper nidus, + with sustenance, and with oxygenation; and that the idea of the semen of + the male constituting only a stimulus to the egg of the female, exciting + it into life, (as held by some philosophers) has no support from + experiment or analogy.</p> + + <p><a name="sect_XXXIX_3">III</a>. <a name="sect_XXXIX_3_1">1</a>. Many + ingenious philosophers have found so great difficulty in conceiving the + manner of the reproduction of animals, that they have supposed all the + numerous progeny, to have existed in miniature in the animal originally + created; and that these infinitely minute forms are only evolved or + distended, as the embryon increases in the womb. This idea, besides its + being unsupported by any analogy we are acquainted with, ascribes a + greater tenuity to organized matter, than we can readily admit; as these + included embryons are supposed each of them to consist of the various and + complicate parts of animal bodies: they must possess a much greater + degree of minuteness, than that which was ascribed to the devils that + tempted St. Anthony; of whom 20,000 were said to have been able to dance + a saraband on the point of the finest needle without incommoding each + other.</p> + + <p><a name="sect_XXXIX_3_2">2</a>. Others have supposed, that all the + parts of the embryon are formed in the male, previous to its being + deposited in the egg or uterus; and that it is then only to have its + parts evolved or distended as mentioned above; but this is only to get + rid of one difficulty by proposing another equally incomprehensible: they + found it difficult to conceive, how the embryon could be formed in the + uterus or egg, and therefore wished it to be formed before it came + thither. In answer to both these doctrines it may be observed, 1st, that + some animals, as the crab-fish, can reproduce a whole limb, as a leg + which has been broken off; others, as worms and snails, can reproduce a + head, or a tail, when either of them has been cut away; and that hence in + these animals at least a part can be formed anew, which cannot be + supposed to have existed previously in miniature.</p> + + <p>Secondly, there are new parts or new vessels produced in many + diseases, as on the cornea of the eye in ophthalmy, in wens and cancers, + which cannot be supposed to have had a prototype or original miniature in + the embryon.</p> + + <p>Thirdly, how could mule-animals be produced, which partake of the + forms of both the parents, if the original embryon was a miniature + existing in the semen of the male parent? if an embryon of the male ass + was only expanded, no resemblance to the mare could exist in the + mule.</p> + + <p>This mistaken idea of the extension of parts seems to have had its + rise from the mature man resembling the general form of the fetus; and + from thence it was believed, that the parts of the fetus were distended + into the man; whereas they have increased 100 times in weight, as well as + 100 times in size; now no one will call the additional 99 parts a + distention of the original one part in respect to weight. Thus the uterus + during pregnancy is greatly enlarged in thickness and solidity as well as + in capacity, and hence must have acquired this additional size by + accretion of new parts, not by an extension of the old ones; the familiar + act of blowing up the bladder of an animal recently slaughtered has led + our imaginations to apply this idea of distention to the increase of size + from natural growth; which however must be owing to the apposition of new + parts; as it is evinced from the increase of weight along with the + increase of dimension; and is even visible to our eyes in the elongation + of our hair from the colour of its ends; or when it has been dyed on the + head; and in the growth of our nails from the specks sometimes observable + on them; and in the increase of the white crescent at their roots, and in + the growth of new flesh in wounds, which consists of new nerves as well + as of new blood-vessels.</p> + + <p><a name="sect_XXXIX_3_3">3</a>. Lastly, Mr. Buffon has with great + ingenuity imagined the existence of certain organic particles, which are + supposed to be partly alive, and partly mechanic springs. The latter of + these were discovered by Mr. Needham in the milt or male organ of a + species of cuttle fish, called calmar; the former, or living animalcula, + are found in both male and female secretions, in the infusions of seeds, + as of pepper, in the jelly of roasted veal, and in all other animal and + vegetable substances. These organic particles he supposes to exist in the + spermatic fluids of both sexes, and that they are derived thither from + every part of the body, and must therefore resemble, as he supposes, the + parts from whence they are derived. These organic particles he believes + to be in constant activity, till they become mixed in the womb, and then + they instantly join and produce an embryon or fetus similar to the two + parents.</p> + + <p>Many objections might be adduced to this fanciful theory, I shall only + mention two. First, that it is analogous to no known animal laws. And + secondly, that as these fluids, replete with organic particles derived + both from the male and female organs, are supposed to be similar; there + is no reason why the mother should not produce a female embryon without + the assistance of the male, and realize the lucina sine concubitu.</p> + + <p><a name="sect_XXXIX_4">IV</a>. <a name="sect_XXXIX_4_1">1</a>. I + conceive the primordium, or rudiment of the embryon, as secreted from the + blood of the parent, to consist of a simple living filament as a muscular + fibre; which I suppose to be an extremity of a nerve of loco-motion, as a + fibre of the retina is an extremity of a nerve of sensation; as for + instance one of the fibrils, which compose the mouth of an absorbent + vessel; I suppose this living filament, of whatever form it may be, + whether sphere, cube, or cylinder, to be endued with the capability of + being excited into action by certain kinds of stimulus. By the stimulus + of the surrounding 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 such rings, are described by those, who have attended to + microscopic animalcula. This living ring may now embrace or absorb a + nutritive particle of the fluid, in which it swims; and by drawing it + into its pores, or joining it by compression to its extremities, may + increase its own length or crassitude; and by degrees the living ring may + become a living tube.</p> + + <p><a name="sect_XXXIX_4_2">2</a>. With this new organization, or + accretion of parts, new kinds of irritability may commence; for so long + as there was but one living organ, it could only be supposed to possess + irritability; since sensibility may be conceived to be an extension of + the effect of irritability over the rest of the system. These new kinds + of irritability and of sensibility in consequence of new organization, + appear from variety of facts in the more mature animal; thus the + formation of the testes, and consequent secretion of the semen, occasion + the passion of lust; the lungs must be previously formed before their + exertions to obtain fresh air can exist; the throat or œsophagus + must be formed previous to the sensation or appetites of hunger and + thirst; one of which seems to reside at the upper end, and the other at + the lower end of that canal.</p> + + <p>Thus also the glans penis, when it is distended with blood, acquires a + new sensibility, and a new appetency. The same occurs to the nipples of + the breasts of female animals, when they are distended with blood, they + acquire the new appetency of giving milk. So inflamed tendons and + membranes, and even bones, acquire new sensations; and the parts of + mutilated animals, as of wounded snails, and polypi, and crabs, are + reproduced; and at the same time acquire sensations adapted to their + situations. Thus when the head of a snail is reproduced after decollation + with a sharp rasor, those curious telescopic eyes are also reproduced, + and acquire their sensibility to light, as well as their adapted muscles + for retraction on the approach of injury.</p> + + <p>With every new change, therefore, of organic form, or addition of + organic parts, I suppose a new kind of irritability or of sensibility to + be produced; such varieties of irritability or of sensibility exist in + our adult state in the glands; every one of which is furnished with an + irritability, or a taste, or appetency, and a consequent mode of action + peculiar to itself.</p> + + <p>In this manner I conceive the vessels of the jaws to produce those of + the teeth, those of the fingers to produce the nails, those of the skin + to produce the hair; in the same manner as afterwards about the age of + puberty the beard and other great changes in the form of the body, and + disposition of the mind, are produced in consequence of the new secretion + of semen; for if the animal is deprived of this secretion those changes + do not take place. These changes I conceive to be formed not by + elongation or distention of primeval stamina, but by apposition of parts; + as the mature crab-fish, when deprived of a limb, in a certain space of + time has power to regenerate it; and the tadpole puts forth its feet long + after its exclusion from the spawn; and the caterpillar in changing into + a butterfly acquires a new form, with new powers, new sensations, and new + desires.</p> + + <p>The natural history of butterflies, and moths, and beetles, and gnats, + is full of curiosity; some of them pass many months, and others even + years, in their caterpillar or grub state; they then rest many weeks + without food, suspended in the air, buried in the earth, or submersed in + water; and change themselves during this time into an animal apparently + of a different nature; the stomachs of some of them, which before + digested vegetable leaves or roots, now only digest honey; they have + acquired wings for the purpose of seeking this new food, and a long + proboscis to collect it from flowers, and I suppose a sense of smell to + detect the secret places in flowers, where it is formed. The moths, which + fly by night, have a much longer proboscis rolled up under their chins + like a watch spring; which they extend to collect the honey from flowers + in their sleeping state; when they are closed, and the nectaries in + consequence more difficult to be plundered. The beetle kind are furnished + with an external covering of a hard material to their wings, that they + may occasionally again make holes in the earth, in which they passed the + former state of their existence.</p> + + <p>But what most of all distinguishes these new animals is, that they are + new furnished with the powers of reproduction; and that they now differ + from each other in sex, which does not appear in their caterpillar or + grub state. In some of them the change from a caterpillar into a + butterfly or moth seems to be accomplished for the sole purpose of their + propagation; since they immediately die after this is finished, and take + no food in the interim, as the silk-worm in this climate; though it is + possible, it might take honey as food, if it was presented to it. For in + general it would seem, that food of a more stimulating kind, the honey of + vegetables instead of their leaves, was necessary for the purpose of the + seminal reproduction of these animals, exactly similar to what happens in + vegetables; in these the juices of the earth are sufficient for their + purpose of reproduction by buds or bulbs; in which the new plant seems to + be formed by irritative motions, like the growth of their other parts, as + their leaves or roots; but for the purpose of seminal or amatorial + reproduction, where sensation is required, a more stimulating food + becomes necessary for the anther, and stigma; and this food is honey; as + explained in Sect. <a href="#sect_XIII">XIII</a>. on Vegetable + Animation.</p> + + <p>The gnat and the tadpole resemble 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 probably of the food, with + which they are supported; and lastly, with their acquiring in their new + state the difference of sex, and the organs of seminal or amatorial + reproduction. While the polypus, who is their companion in their former + state of life, not being allowed to change his form and element, can only + propagate like vegetable buds by the same kind of irritative motions, + which produces the growth of his own body, without the seminal or + amatorial propagation, which requires sensation; and which in gnats and + tadpoles seems to require a change both of food and of respiration.</p> + + <p>From hence I conclude, that with the acquisition of new parts, new + sensations, and new desires, as well as new powers, are produced; and + this by accretion to the old ones, and not by distention of them. And + finally, that the most essential parts of the system, as the brain for + the purpose of distributing the power of life, and the placenta for the + purpose of oxygenating the blood, and the additional absorbent vessels + for the purpose of acquiring aliment, are first formed by the irritations + above mentioned, and by the pleasurable sensations attending those + irritations, and by the exertions in consequence of painful sensations, + similar to those of hunger and suffocation. After these an apparatus of + limbs for future uses, or for the purpose of moving the body in its + present natant state, and of lungs for future respiration, and of testes + for future reproduction, are formed by the irritations and sensations, + and consequent exertions of the parts previously existing, and to which + the new parts are to be attached.</p> + + <p><a name="sect_XXXIX_4_3">3</a>. In confirmation of these ideas it may + be observed, that all the parts of the body endeavour to grow, or to make + additional parts to themselves throughout our lives; but are restrained + by the parts immediately containing them; thus, if the skin be taken + away, the fleshy parts beneath soon shoot out new granulations, called by + the vulgar proud flesh. If the periosteum be removed, a similar growth + commences from the bone. Now in the case of the imperfect embryon, the + containing or confining parts are not yet supposed to be formed, and + hence there is nothing to restrain its growth.</p> + + <p><a name="sect_XXXIX_4_4">4</a>. By the parts of the embryon being thus + produced by new apportions, many phenomena both of animal and vegetable + productions receive an easier explanation; such as that many fetuses 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 deficiency of the + palate. For if there should be a deficiency in the quantity of the first + nutritive particles laid up in the egg for the reception of the first + living filament, the extreme parts, as being last formed, must shew this + deficiency by their being imperfect.</p> + + <p>This idea of the growth of the embryon accords also with the + production of some monstrous births, which consist of a duplicature of + the limbs, as chickens with four legs; which could not occur, if the + fetus was formed by the distention of an original stamen, or miniature. + For if there should be a superfluity of the first nutritive particles + laid up in the egg for the first living filament; it is easy to conceive, + that a duplicature of some parts may be formed. And that such superfluous + nourishment sometimes exists, is evinced by the double yolks in some + eggs, which I suppose were thus formed previous to their impregnation by + the exuberant nutriment of the hen.</p> + + <p>This idea is confirmed by the analogy of the monsters in the vegetable + world also; in which a duplicate or triplicate production of various + parts of the flower is observable, as a triple nectary in some + columbines, and a triple petal in some primroses; and which are supposed + to be produced by abundant nourishment.</p> + + <p><a name="sect_XXXIX_4_5">5</a>. If the embryon be received into a + fluid, whose stimulus is different in some degree from the natural, as in + the production of mule-animals, the new irritabilities or sensibilities + acquired by the increasing or growing organized parts may differ, and + thence produce parts not similar to the father, but of a kind belonging + in part to the mother; and thus, though the original stamen or living ens + was derived totally from the father, yet new irritabilities or + sensibilities being excited, a change of form corresponding with them + will be produced. Nor could the production of mules exist, if the stamen + or miniature of all the parts of the embryon is previously formed in the + male semen, and is only distended by nourishment in the female uterus. + Whereas this difficulty ceases, if the embryon be supposed to consist of + a living filament, which acquires or makes new parts with new + irritabilities, as it advances in its growth.</p> + + <p>The form, solidity, and colour, of the particles of nutriment laid up + for the reception of the first living filament, as well as their peculiar + kind of stimulus, may contribute to produce a difference in the form, + solidity, and colour of the fetus, so as to resemble the mother, as it + advances in life. This also may especially happen during the first state + of the existence of the embryon, before it has acquired organs, which can + change these first nutritive particles, as explained in No. <a + href="#sect_XXXIX_5_2">5. 2</a>. of this Section. And as these nutritive + particles are supposed to be similar to those, which are formed for her + own nutrition, it follows that the fetus should so far resemble the + mother.</p> + + <p>This explains, why hereditary diseases may be derived either from the + male or female parent, as well as the peculiar form of either of their + bodies. Some of these hereditary diseases are simply owing to a deficient + activity of a part of the system, as of the absorbent vessels, which open + into the cells or cavities of the body, and thus occasion dropsies. + Others are at the same time owing to an increase of sensation, as in + scrophula and consumption; in these the obstruction of the fluids is + first caused by the inirritability of the vessels, and the inflammation + and ulcers which succeed, are caused by the consequent increase of + sensation in the obstructed part. Other hereditary diseases, as the + epilepsy, and other convulsions, consist in too great voluntary exertions + in consequence of disagreeable sensation in some particular diseased + part. Now as the pains, which occasion these convulsions, are owing to + defect of the action of the diseased part, as shewn in Sect. <a + href="#sect_XXXIV">XXXIV</a>. it is plain, that all these hereditary + diseases may have their origin either from defective irritability derived + from the father, or from deficiency of the stimulus of the nutriment + derived from the mother. In either case the effect would be similar; as a + scrophulous race is frequently produced among the poor from the deficient + stimulus of bad diet, or of hunger; and among the rich, by a deficient + irritability from their having been long accustomed to too great + stimulus, as of vinous spirit.</p> + + <p><a name="sect_XXXIX_4_6">6</a>. From this account of reproduction it + appears, that all animals have a similar origin, viz. from a single + living filament; and that the difference of their forms and qualities has + arisen only from the different irritabilities and sensibilities, or + voluntarities, or associabilities, of this original living filament; and + perhaps in some degree from the different forms of the particles of the + fluids, by which it has been at first stimulated into activity. And that + from hence, as Linnæus has conjectured in respect to the vegetable world, + it is not impossible, but the great variety of species of animals, which + now tenant the earth, may have had their origin from the mixture of a few + natural orders. And that those animal and vegetable mules, which could + continue their species, have done so, and constitute the numerous + families of animals and vegetables which now exist; and that those mules, + which were produced with imperfect organs of generation, perished without + reproduction, according to the observation of Aristotle; and are the + animals, which we now call mules. See Botanic Garden, Part II. Note on + Dianthus.</p> + + <p>Such a promiscuous intercourse of animals is said to exist at this day + in New South Wales by Captain Hunter. And that not only amongst the + quadrupeds and birds of different kinds, but even amongst the fish, and, + as he believes, amongst the vegetables. He speaks of an animal between + the opossum and the kangaroo, from the size of a sheep to that of a rat. + Many fish seemed to partake of the shark; some with a shark's head and + shoulders, and the hind part of a shark; others with a shark's head and + the body of a mullet; and some with a shark's head and the flat body of a + sting-ray. Many birds partake of the parrot; some have the head, neck, + and bill of a parrot, with long straight feet and legs; others with legs + and feet of a parrot, with head and neck of a sea gull. Voyage to South + Wales by Captain John Hunter, p. 68.</p> + + <p><a name="sect_XXXIX_4_7">7</a>. All animals therefore, I contend, have + a similar cause of their organization, originating from a single living + filament, endued indeed with different kinds of irritabilities and + sensibilities, or of animal appetencies; which exist in every gland, and + in every moving organ of the body, and are as essential to living + organization as chemical affinities are to certain combinations of + inanimate matter.</p> + + <p>If I might be indulged to make a simile in a philosophical work, I + should say, that the animal appetencies are not only perhaps less + numerous originally than the chemical affinities; but that like these + latter, they change with every new combination; thus vital air and azote, + when combined, produce nitrous acid; which now acquires the property of + dissolving silver; so with every new additional part to the embryon, as + of the throat or lungs, I suppose a new animal appetency to be + produced.</p> + + <p>In this early formation of the embryon from the irritabilities, + sensibilities, and associabilities, and consequent appetencies, the + faculty of volition can scarcely be supposed to have had its birth. For + about what can the fetus deliberate, when it has no choice of objects? + But in the more advanced state of the fetus, it evidently possesses + volition; as it frequently changes its attitude, though it seems to sleep + the greatest 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 + life. All these faculties then constitute the vis fabricatrix, and the + vis conservatrix, as well as the vis medicatrix of nature, so much spoken + of, but so little understood by philosophers.</p> + + <p><a name="sect_XXXIX_4_8">8</a>. When we revolve in our minds, first, + the great changes, which we see naturally produced in animals after their + nativity, as in the production of the butterfly with painted wings from + the crawling caterpillar; or of the respiring frog from the subnatant + tadpole; from the feminine boy to the bearded man, and from the infant + girl to the lactescent woman; both which changes may be prevented by + certain mutilations of the glands necessary to reproduction.</p> + + <p>Secondly, when we think over the great changes introduced into various + animals by artificial or accidental cultivation, as in horses, which we + have exercised for the different purposes of strength or swiftness, in + carrying burthens or in running races; or in dogs, which have been + cultivated for strength and courage, as the bull-dog; or for acuteness of + his sense or smell, as the hound and spaniel; or for the swiftness of his + foot, as the greyhound; or for his swimming in the water, or for drawing + snow-sledges, as the rough-haired dogs of the north; or lastly, as a + play-dog for children, as the lap-dog; with the changes of the forms of + the cattle, which have been domesticated from the greatest antiquity, as + camels, and sheep; which have undergone so total a transformation, that + we are now ignorant from what species of wild animals they had their + origin. Add to these the great changes of shape and colour, which we + daily see produced in smaller animals from our domestication of them, as + rabbits, or pigeons; or from the difference of climates and even of + seasons; thus the sheep of warm climates are covered with hair instead of + wool; and the hares and partridges of the latitudes, which are long + buried in snow, become white during the winter months; add to these the + various changes produced in the forms of mankind, by their early modes of + exertion; or by the diseases occasioned by their habits of life; both of + which became hereditary, and that through many generations. Those who + labour at the anvil, the oar, or the loom, as well as those who carry + sedan-chairs, or who have been educated to dance upon the rope, are + distinguishable by the shape of their limbs; and the diseases occasioned + by intoxication deform the countenance with leprous eruptions, or the + body with tumid viscera, or the joints with knots and distortions.</p> + + <p>Thirdly, when we enumerate the great changes produced in the species + of animals before their nativity; these are such as resemble the form or + colour of their parents, which have been altered by the cultivation or + accidents above related, and are thus continued to their posterity. Or + they are changes produced by the mixture of species as in mules; or + changes produced probably by the exuberance of nourishment supplied to + the fetus, as in monstrous births with additional limbs; many of these + enormities of shape are propagated, and continued as a variety at least, + if not as a new species of animal. I have seen a breed of cats with an + additional claw on every foot; of poultry also with an additional claw, + and with wings to their feet; and of others without rumps. Mr. Buffon + mentions a breed of dogs without tails, which are common at Rome and at + Naples, which he supposes to have been produced by a custom long + established of cutting their tails close off. There are many kinds of + pigeons, admired for their peculiarities, which are monsters thus + produced and propagated. And to these must be added, the changes produced + by the imagination of the male parent, as will be treated of more at + large in No. <a href="#sect_XXXIX_6">VI</a>. of this Section.</p> + + <p>When we consider all these changes of animal form, and innumerable + others, which may be collected from the books of natural history; we + cannot but be convinced, that the fetus or embryon is formed by + apposition of new parts, and not by the distention of a primordial nest + of germs, included one within another, like the cups of a conjurer.</p> + + <p>Fourthly, when we revolve in our minds the great similarity of + structure, which obtains in all the warm-blooded animals, as well + quadrupeds, birds, and amphibious animals, as in mankind; from the mouse + and bat to the elephant and whale; one is led to conclude, that they have + alike been produced from a similar living filament. In some this filament + in its advance to maturity has acquired hands and fingers, with a fine + sense of touch, as in mankind. In others it has acquired claws or talons, + as in tygers and eagles. In others, toes with an intervening web, or + membrane, as in seals and geese. In others it has acquired cloven hoofs, + as in cows and swine; and whole hoofs in others, as in the horse. While + in the bird kind this original living filament has put forth wings + instead of arms or legs, and feathers instead of hair. In some it has + protruded horns on the forehead instead of teeth in the fore part of the + upper jaw; in others tushes instead of horns; and in others beaks instead + of either. And all this exactly as is daily seen in the transmutations of + the tadpole, which acquires legs and lungs, when he wants them; and loses + his tail, when it is no longer of service to him.</p> + + <p>Fifthly, from their first rudiment, or primordium, to the termination + of their lives, all animals undergo perpetual transformations; which are + in part produced by their own exertions in consequence of their desires + and aversions, of their pleasures and their pains, or of irritations, or + of associations; and many of these acquired forms or propensities are + transmitted to their posterity. See Sect. <a href="#sect_XXXI_1">XXXI. + 1</a>.</p> + + <p>As air and water are supplied to animals in sufficient profusion, the + three great objects of desire, which have changed the forms of many + animals by their exertions to gratify them, are those of lust, hunger, + and security. A great want of one part of the animal world has consisted + in the desire of the exclusive possession of the females; and these have + acquired weapons to combat each other for this purpose, as the very + thick, shield-like, horny skin on the shoulder of the boar is a defence + only against animals of his own species, who strike obliquely upwards, + nor are his tushes for other purposes, except to defend himself, as he is + not naturally a carnivorous animal. So the horns of the stag are sharp to + offend his adversary, but are branched for the purpose of parrying or + receiving the thrusts of horns similar to his own, and have therefore + been formed for the purpose of combating other stags for the exclusive + possession of the females; who are observed, like the ladies in the times + of chivalry, to attend the car of the victor.</p> + + <p>The birds, which do not carry food to their young, and do not + therefore marry, are armed with spurs for the purpose of fighting for the + exclusive possession of the females, as cocks and quails. It is certain + that these weapons are not provided for their defence against other + adversaries, because the females of these species are without this + armour. The final cause of this contest amongst the males seems to be, + that the strongest and most active animal should propagate the species, + which should thence become improved.</p> + + <p>Another great want consists in the means of procuring food, which has + diversified the forms of all species of animals. Thus the nose of the + swine has become hard for the purpose of turning up the soil in search of + insects and of roots. The trunk of the elephant is an elongation of the + nose for the purpose of pulling down the branches of trees for his food, + and for taking up water without bending his knees. Beasts of prey have + acquired strong jaws or talons. Cattle have acquired a rough tongue and a + rough palate to pull off the blades of grass, as cows and sheep. Some + birds have acquired harder beaks to crack nuts, as the parrot. Others + have acquired beaks adapted to break the harder seeds, as sparrows. + Others for the softer seeds of flowers, or the buds of trees, as the + finches. Other birds have acquired long beaks to penetrate the moister + soils in search of insects or roots, as woodcocks; and others broad ones + to filtrate the water of lakes, and to retain aquatic insects. All which + seem to have been gradually produced during many generations by the + perpetual endeavour of the creatures to supply the want of food, and to + have been delivered to their posterity with constant improvement of them + for the purposes required.</p> + + <p>The third great want amongst animals is that of security, which seems + much to have diversified the forms of their bodies and the colour of + them; these consist in the means of escaping other animals more powerful + than themselves. Hence some animals have acquired wings instead of legs, + as the smaller birds, for the purpose of escape. Others great length of + fin, or of membrane, as the flying fish, and the bat. Others great + swiftness of foot, as the hare. Others have acquired hard or armed + shells, as the tortoise and the echinus marinus.</p> + + <p>Mr. Osbeck, a pupil of Linnæus, mentions the American frog fish, + Lophius Histrio, which inhabits the large floating islands of sea-weed + about the Cape of Good Hope, and has fulcra resembling leaves, that the + fishes of prey may mistake it for the sea-weed, which it inhabits. Voyage + to China, p. 113.</p> + + <p>The contrivances for the purposes of security extend even to + vegetables, as is seen in the wonderful and various means of their + concealing or defending their honey from insects, and their seeds from + birds. On the other hand swiftness of wing has been acquired by hawks and + swallows to pursue their prey; and a proboscis of admirable structure has + been acquired by the bee, the moth, and the humming bird, for the purpose + of plundering the nectaries of flowers. All which seem to have been + formed by the original living filament, excited into action by the + necessities of the creatures, which possess them, and on which their + existence depends.</p> + + <p>From thus meditating on the great similarity of the structure of the + warm-blooded animals, and at the same 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 described + have been produced; would it be too bold to imagine, that in the great + length of time, since the earth began to exist, perhaps millions of ages + before the commencement of the history of mankind, would it be too bold + to imagine, that all warm-blooded animals have arisen from one living + filament, which <font class="sc">THE GREAT</font> F<font + class="sc">IRST</font> C<font class="sc">AUSE</font> endued with + animality, with the power of acquiring new parts, attended with new + propensities, directed by irritations, sensations, volitions, and + associations; and thus possessing the faculty of continuing to improve by + its own inherent activity, and of delivering down those improvements by + generation to its posterity, world without end!</p> + + <p>Sixthly, The cold-blooded animals, as the fish-tribes, which are + furnished with but one ventricle of the heart, and with gills instead of + lungs, and with fins instead of feet or wings, bear a great similarity to + each other; but they differ, nevertheless, so much in their general + structure from the warm-blooded animals, that it may not seem probable at + first view, that the same living filament could have given origin to this + kingdom of animals, as to the former. Yet are there some creatures, which + unite or partake of both these orders of animation, as the whales and + seals; and more particularly the frog, who changes from an aquatic animal + furnished with gills to an aerial one furnished with lungs.</p> + + <p>The numerous tribes of insects without wings, from the spider to the + scorpion, from the flea to the lobster; or with wings, from the gnat and + the ant to the wasp and the dragon-fly, differ so totally from each + other, and from the red-blooded classes above described, both in the + forms of their bodies, and their modes of life; besides the organ of + sense, which they seem to possess in their antennæ or horns, to which it + has been thought by some naturalists, that other creatures have nothing + similar; that it can scarcely be supposed that this nation of animals + could have been produced by the same kind of living filament, as the + red-blooded classes above mentioned. And yet the changes which many of + them undergo in their early state to that of their maturity, are as + different, as one animal can be from another. As those of the gnat, which + passes his early state in water, and then stretching out his new wings, + and expanding his new lungs, rises in the air; as of the caterpillar, and + bee-nymph, which feed on vegetable leaves or farina, and at length + bursting from their self-formed graves, become beautiful winged + inhabitants of the skies, journeying from flower to flower, and nourished + by the ambrosial food of honey.</p> + + <p>There is still another class of animals, which are termed vermes by + Linnæus, which are without feet, or brain, and are hermaphrodites, as + worms, leeches, snails, shell-fish, coralline insects, and sponges; which + possess the simplest structure of all animals, and appear totally + different from those already described. The simplicity of their + structure, however, can afford no argument against their having been + produced from a living filament as above contended.</p> + + <p>Last of all the various tribes of vegetables are to be enumerated + amongst the inferior orders of animals. Of these the anthers and stigmas + have already been shewn to possess some organs of sense, to be nourished + by honey, and to have the power of generation like insects, and have + thence been announced amongst the animal kingdom in Sect. <a + href="#sect_XIII">XIII</a>. and to these must be added the buds and bulbs + which constitute the viviparous offspring of vegetation. The former I + suppose to be beholden to a single living filament for their seminal or + amatorial procreation; and the latter to the same cause for their lateral + or branching generation, which they possess in common with the polypus, + tænia, and volvox; and the simplicity of which is an argument in favour + of the similarity of its cause.</p> + + <p>Linnæus supposes, in the Introduction to his Natural Orders, that very + few vegetables were at first created, and that their numbers were + increased by their intermarriages, and adds, suadent hæc Creatoris leges + a simplicibus ad composita. Many other changes seem to have arisen in + them by their perpetual contest for light and air above ground, and for + food or moisture beneath the soil. As noted in Botanic Garden, Part II. + Note on Cuscuta. Other changes of vegetables from climate, or other + causes, are remarked in the Note on Curcuma in the same work. From these + one might be led to imagine, that each plant at first consisted of a + single bulb or flower to each root, as the gentianella and daisy; and + that in the contest for air and light new buds grew on the old decaying + flower stem, shooting down their elongated roots to the ground, and that + in process of ages tall trees were thus formed, and an individual bulb + became a swarm of vegetables. Other plants, which in this contest for + light and air were too slender to rise by their own strength, learned by + degrees to adhere to their neighbours, either by putting forth roots like + the ivy, or by tendrils like the vine, or by spiral contortions like the + honeysuckle; or by growing upon them like the misleto, and taking + nourishment from their barks; or by only lodging or adhering on them, and + deriving nourishment from the air, as tillandsia.</p> + + <p>Shall we then say that the vegetable living filament was originally + different from that of each tribe of animals above described? And that + the productive living filament of each of those tribes was different + originally from the other? Or, as the earth and ocean were probably + peopled with vegetable productions long before the existence of animals; + and many families of these animals long before other families of them, + shall we conjecture that one and the same kind of living filaments is and + has been the cause of all organic life?</p> + + <p>This idea of the gradual formation and improvement of the animal world + accords with the observations of some modern philosophers, who have + supposed that the continent of America has been raised 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 consequent greater coldness of its respective climates, and from + the less size and strength of its animals, as the tygers and allegators + compared with those of Asia or Africa. And lastly, from the less progress + in the improvements of the mind of its inhabitants in respect to + voluntary exertions.</p> + + <p>This idea of the gradual formation and improvement of the animal world + seems not to have been unknown to the ancient philosophers. Plato having + probably observed the reciprocal generation of inferior animals, as + snails and worms, was of opinion, that mankind with all other animals + were originally hermaphrodites during the infancy of the world, and were + in process of time separated into male and female. The breasts and teats + of all male quadrupeds, to which no use can be now assigned, adds perhaps + some shadow of probability to this opinion. Linnæus excepts the horse + from the male quadrupeds, who have teats; which might have shewn the + earlier origin of his exigence; but Mr. J. Hunter asserts, that he has + discovered the vestiges of them on his sheath, and has at the same time + enriched natural history with a very curious fact concerning the male + pigeon; at the time of hatching the eggs both the male and female pigeon + undergo a great change in their crops; which thicken and become + corrugated, and secrete 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 resembles + the breasts of female quadrupeds after the production of their young! and + how extraordinary, that the male should at this time give milk as well as + the female! See Botanic Garden, Part II. Note on Curcuma.</p> + + <p>The late Mr. David Hume, in his posthumous works, places the powers of + generation much above those of our boasted reason; and adds, that reason + can only make a machine, as a clock or a ship, but the power of + generation makes the maker of the machine; and probably from having + observed, that the greatest part of the earth has been formed out of + organic recrements; as the immense beds of limestone, chalk, marble, from + the shells of fish; and the extensive provinces of clay, sandstone, + ironstone, coals, from decomposed vegetables; all which have been first + produced by generation, or by the secretions of organic life; he + concludes that the world itself might have been generated, rather than + created; that is, it might have been gradually produced from very small + beginnings, increasing by the activity of its inherent principles, rather + than by a sudden evolution of the whole by the Almighty fire.—What + a magnificent idea of the infinite power of <font class="sc">THE</font> + G<font class="sc">REAT</font> A<font class="sc">RCHITECT</font>! T<font + class="sc">HE</font> C<font class="sc">AUSE OF</font> C<font + class="sc">AUSES</font>! P<font class="sc">ARENT OF</font> P<font + class="sc">ARENTS</font>! E<font class="sc">NS</font> E<font + class="sc">NTIUM</font>!</p> + + <p>For if we may compare infinities, it would seem to require a greater + infinity of power to cause the causes of effects, than to cause the + effects themselves. This idea is analogous to the improving excellence + observable in every part of the creation; such as in the progressive + increase of the solid or habitable parts of the earth from water; and in + the progressive increase of the wisdom and happiness of its inhabitants; + and is consonant to the idea of our present situation being a state of + probation, which by our exertions we may improve, and are consequently + responsible for our actions.</p> + + <p><a name="sect_XXXIX_5">V</a>. <a name="sect_XXXIX_5_1">1</a>. The + efficient cause of the various colours of the eggs of birds, and of the + air and feathers of animals, is a subject so curious, that I shall beg to + introduce it in this place. The colours of many animals seem adapted to + their purposes of concealing themselves either to avoid danger, or to + spring upon their prey. Thus the snake and wild cat, and leopard, are so + coloured as to resemble dark leaves and their lighter interstices; birds + resemble the colour of the brown ground, or the green hedges, which they + frequent; and moths and butterflies are coloured like the flowers which + they rob of their honey. Many instances are mentioned of this kind in + Botanic Garden, p. 2. Note on Rubia.</p> + + <p>These colours have, however, in some instances another use, as the + black diverging area from the eyes of the swan; which, as his eyes are + placed less prominent than those of other birds, for the convenience of + putting down his head under water, prevents the rays of light from being + reflected into his eye, and thus dazzling his sight, both in air and + beneath the water; which must have happened, if that surface had been + white like the rest of his feathers.</p> + + <p>There is a still more wonderful thing concerning these colours adapted + to the purpose of concealment; which is, that the eggs of birds are so + coloured as to resemble the colour of the adjacent objects and their + interfaces. The eggs of hedge-birds are greenish with dark spots; those + of crows and magpies, which are seen from beneath through wicker nests, + are white with dark spots; and those of larks and partridges are russet + or brown, like their nests or situations.</p> + + <p>A thing still more astonishing is, that many animals in countries + covered with snow become white in winter, and are said to change their + colour again in the warmer months, as bears, hares, and partridges. Our + domesticated animals lose their natural colours, and break into great + variety, as horses, dogs, pigeons. The final cause of these colours is + easily understood, as they serve some purposes of the animal, but the + efficient cause would seem almost beyond conjecture.</p> + + <p>First, the choroid coat of the eye, on which the semitransparent + retina is expanded, is of different colour in different animals; in those + which feed on grass it is green; from hence there would appear some + connexion between the colour of the choroid coat and of that constantly + painted on the retina by the green grass. Now, when the ground becomes + covered with snow, it would seem, that that action of the retina, which + is called whiteness, being constantly excited in the eye, may be + gradually imitated by the extremities of the nerves of touch, or rete + mucosum of the skin. And if it be supposed, that the action of the retina + in producing the perception of any colour consists in so disposing its + own fibres or surface, as to reflect those coloured rays only, and + transmit the others like soap-bubbles; then that part of the retina, + which gives us the perception of snow, must at that time be white; and + that which gives us the perception of grass, must be green.</p> + + <p>Then if by the laws of imitation, as explained in Section <a + href="#sect_XII_3_3">XII. 3. 3</a>. and <a href="#sect_XXXIX_6">XXXIX. + 6</a>. the extremities of the nerves of touch in the rete mucosum be + induced into similar action, the skin or feathers, or hair, may in like + manner so dispose their extreme fibres, as to reflect white; for it is + evident, that all these parts were originally obedient to irritative + motions during their growth, and probably continue to be so; that those + irritative motions are not liable in a healthy state to be succeeded by + sensation; which however is no uncommon thing in their diseased state, or + in their infant state, as in plica polonica, and in very young + pen-feathers, which are still full of blood.</p> + + <p>It was shewn in Section <a href="#sect_XV">XV</a>. on the Production + of Ideas, that the moving organ of sense in some circumstances resembled + the object which produced that motion. Hence it may be conceived, that + the rete mucosum, which is the extremity of the nerves of touch, may by + imitating the motions of the retina become coloured. And thus, like the + fable of the camelion, all animals may possess a tendency to be coloured + somewhat like the colours they most frequently inspect, and finally, that + colours may be thus given to the egg-shell by the imagination of the + female parent; which shell is previously a mucous membrane, indued with + irritability, without which it could not circulate its fluids, and + increase in its bulk. Nor is this more wonderful than that a single idea + of imagination mould in an instant colour the whole surface of the body + of a bright scarlet, as in the blush of shame, though by a very different + process. In this intricate subject nothing but loose analogical + conjectures can be had, which may however lead to future discoveries; but + certain it is that both the change of the colour of animals to white in + the winters of snowy countries, and the spots on birds eggs, must have + some efficient cause; since the uniformity of their production shews it + cannot arise from a fortuitous concurrence of circumstances; and how is + this efficient cause to be detected, or explained, but from its analogy + to other animal facts?</p> + + <p><a name="sect_XXXIX_5_2">2</a>. The nutriment supplied by the female + parent in viviparous animals to their young progeny may be divided into + three kinds, corresponding with the age of the new creature. 1. The + nutriment contained in the ovum as previously prepared for the embryon in + the ovary. 2. The liquor amnii prepared for the fetus in the uterus, and + in which it swims; and lastly, the milk prepared in the pectoral glands + for the new born-child. There is reason to conclude that variety of + changes may be produced in the new animal from all these sources of + nutriment, but particularly from the first of them..</p> + + <p>The organs of digestion and of sanguification in adults, and + afterwards those of secretion, prepare or separate the particles proper + for nourishment from other combinations of matter, or recombine them into + new kinds of matter, proper to excite into action the filaments, which + absorb or attract them by animal appetency. In this process we must + attend not only to the action of the living filament which receives a + nutritive particle to its bosom, but also to the kind of particle, in + respect to form, or size, or colour, or hardness, which is thus + previously prepared for it by digestion, sanguification, and secretion. + Now as the first filament of entity cannot be furnished with the + preparative organs above mentioned, the nutritive particles, which are at + first to be received by it, are prepared by the mother; and deposited in + the ovum ready for its reception. These nutritive particles must be + supposed to differ in some respects, when thus prepared by different + animals. They may differ in size, solidity, colour, and form; and yet may + be sufficiently congenial to the living filament, to which they are + applied, as to excite its activity by their stimulus, and its animal + appetency to receive them, and to combine them with itself into + organization.</p> + + <p>By this first 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 prepared, I suppose, in the ovary + of viviparous animals, and that which immediately surrounds the + cicatricula of an impregnated egg, and is visible to the eye in a boiled + one.</p> + + <p>Now these ultimate particles of animal matter prepared by the glands + of the mother may be supposed to resemble the similar ultimate particles, + which were prepared for her own nourishment; that is, to the ultimate + particles of which her own organization consists. And that hence when + these become combined with a new embryon, which in its early state is not + furnished with stomach, or glands, to alter them; that new embryon will + bear some resemblance to the mother.</p> + + <p>This seems 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 antients seem to have indulged their + fancies, whence the sphinxes, griffins, dragons, centaurs, and minotaurs, + which are vanished from modern credulity.</p> + + <p>It would seem, that in these unnatural conjunctions, when the + nutriment deposited by the female was so ill adapted to stimulate 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 necessary to life, as the brain, or heart, or stomach, that no + mule was produced. Where all the parts necessary to life in these + compound animals were formed sufficiently perfect, except the parts of + generation, those animals were produced which are now called mules.</p> + + <p>The formation of the organs of sexual generation, in contradistinction + to that by lateral buds, in vegetables, and in some animals, as the + polypus, the tænia, and the volvox, seems the chef d'œuvre, the + master-piece of nature; as appears from many flying insects, as in moths + and butterflies, who seem to undergo a general change of their forms + solely for the purpose of sexual 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 species, the + parts necessary to life are frequently completely formed; but those for + the purpose of generation are defective, as requiring a nicer + organization; or more exact coincidence of the particles of nutriment to + the irritabilities or appetencies of the original living filament. + Whereas those 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 species of animals, as before observed.</p> + + <p>As this production of mules is a constant effect from the conjunction + of different species of animals, those between the horse and the female + ass always resembling the horse more than the ass; and those, on the + contrary, between the male ass and the mare, always resembling the ass + more than the mare; it cannot be ascribed to the imagination of the male + animal which cannot be supposed to operate so uniformly; but to the form + of the first nutritive particles, and to their peculiar stimulus exciting + the living filament to select and combine them with itself. There is a + similar uniformity of effect in respect 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 + supplied to the embryon by the mother at the early period of its + existence, and their peculiar stimulus; as this effect, like that of the + mule progeny above treated of, is uniform and consistent, and cannot + therefore be ascribed to the imagination of either of the parents.</p> + + <p>Dr. Thunberg observes, in his Journey to the Cape of Good Hope, that + there are some families, which have descended from blacks in the female + line for three generations. The first generation proceeding from an + European, who married a tawny slave, 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. V. i. + p. 112.</p> + + <p>When the embryon has produced a placenta, and furnished itself with + vessels for selection 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 sustenance it now takes from the fluid, in which it is + immersed; because it has now acquired organs to alter or new combine + them. Hence it continues to grow, whether this fluid, in which it swims, + be formed by the uterus or by any other cavity of the body, as in + extra-uterine gestation; and which would seem to be produced by the + stimulus of the fetus on the sides of the cavity, where it is found, as + mentioned before. And thirdly, there is still less reason to expect any + unnatural change to happen to the child after its birth from the + difference of the milk it now takes; because it has acquired a stomach, + and lungs, and glands, of sufficient power to decompose and recombine the + milk; and thus to prepare from it the various kinds of nutritious + particles, which the appetencies of the various fibrils or nerves may + require.</p> + + <p>From all this reasoning I would conclude, that though the imagination + of the female may be supposed to affect the embryon by producing a + difference in its early nutriment; yet that no such power can affect it + after it has obtained a placenta, and other organs; which may select or + change the food, which is presented to it either in the liquor amnii, or + in the milk. Now as the eggs in pullets, like the seeds in vegetables, + are produced gradually, long before they are impregnated, it does not + appear how any sudden effect of imagination of the mother at the time of + impregnation can produce any considerable change in the nutriment already + thus laid up for the expected or desired embryon. And that hence any + changes of the embryon, except those uniform ones in the production of + mules and mulattoes, more probably depend on the imagination of the male + parent. At the same time it seems manifest, that those monstrous births, + which consist in some deficiencies only, or some redundancies of parts, + originate from the deficiency or redundance of the first nutriment + prepared in the ovary, or in the part of the egg immediately surrounding + the cicatricula, as described above; and which continues some time to + excite the first living filament into action, after the simple animal is + completed; or ceases to excite it, before the complete form is + accomplished. The former of these circumstances is evinced by the eggs + with double yolks, which frequently happen to our domesticated poultry, + and which, I believe, are so formed before impregnation, but which would + be well worth attending to, both before and after impregnation; as it is + probable, something valuable on this subject might be learnt from them. + The latter circumstance, or that of deficiency of original nutriment, may + be deduced from reverse analogy.</p> + + <p>There are, however, other kinds of monstrous births, which neither + depend on deficiency of parts, or supernumerary ones; nor are owing to + the conjunction of animals of different species; but which appear to be + new conformations, or new dispositions of parts in respect to each other, + and which, like the variation of colours and forms of our domesticated + animals, and probably the sexual parts of all animals, may depend on the + imagination of the male parent, which we now come to consider.</p> + + <p><a name="sect_XXXIX_6">VI</a>. <a name="sect_XXXIX_6_1">1</a>. The + nice actions of the extremities of our various glands are exhibited in + their various productions, which are believed to be made by the gland, + and not previously to exist as such in the blood.</p> + + <p>Thus the glands, which constitute the liver, make bile; those of the + stomach make gastric acid; those beneath the jaw, saliva; those of the + ears, ear-wax; and the like. Every kind of gland must possess a peculiar + irritability, and probably a sensibility, at the early state of its + existence; and must be furnished with a nerve of sense, or of motion, to + perceive, and to select, and to combine the particles, which compose the + fluid it secretes. And this nerve of sense which perceives the different + articles which compose the blood, must at least be conceived to be as + fine and subtile an organ, as the optic or auditory nerve, which perceive + light or sound. See Sect. <a href="#sect_XIV_9">XIV. 9</a>.</p> + + <p>But in nothing is this nice action of the extremities of the + blood-vessels so wonderful, as in the production of contagious matter. A + small drop of variolous contagion diffused in the blood, or perhaps only + by being inserted beneath the cuticle, after a time, (as about a quarter + of a lunation,) excites the extreme vessels of the skin into certain + motions, which produce a similar contagious material, filling with it a + thousand pustules. So that by irritation, or by sensation in consequence + of irritation, or by association of motions, a material is formed by the + extremities of certain cutaneous vessels, exactly similar to the + stimulating material, which caused the irritation, or consequent + sensation, or association.</p> + + <p>Many glands of the body have their motions, and in consequence their + secreted fluids, affected by pleasurable or painful ideas, since they are + in many instances influenced by sensitive associations, as well as by the + irritations of the particles of the passing blood. Thus the idea of meat, + excited in the minds of hungry dogs, by their sense of vision, or of + smell, increases the discharge of saliva, both in quantity and viscidity; + as is seen in its hanging down in threads from their mouths, as they + stand round a dinner-table. The sensations of pleasure, or of pain, of + peculiar kinds, excite in the same manner a great discharge of tears; + which appear also to be more saline at the time of their secretion, from + their inflaming the eyes and eye-lids. The paleness from fear, and the + blush of shame, and of joy, are other instances of the effects of + painful, or pleasurable sensations, on the extremities of the arterial + system.</p> + + <p>It is probable, that the pleasurable sensation excited in the stomach + by food, as well as its irritation, contributes to excite into action the + gastric glands, and to produce a greater secretion of their fluids. The + same probably occurs in the secretion of bile; that is, that the + pleasurable sensation excited in the stomach, affects this secretion by + sensitive association, as well as by irritative association.</p> + + <p>And lastly it would seem, that all the glands in the body have their + secreted fluids affected, in quantity and quality, by the pleasurable or + painful sensations, which produce or accompany those secretions. And that + the pleasurable sensations arising from these secretions may constitute + the unnamed pleasure of exigence, which is contrary to what is meant by + tedium vitæ, or ennui; and by which we sometimes feel ourselves happy, + without being able to ascribe it to any mental cause, as after an + agreeable meal, or in the beginning of intoxication.</p> + + <p>Now it would appear, that no secretion or excretion of fluid is + attended with so much agreeable sensation, as that of the semen; and it + would thence follow, that the glands, which perform this secretion, are + more likely to be much affected by their catenations with pleasurable + sensations. This circumstance is certain, that much more of this fluid is + produced in a given time, when the object of its exclusion is agreeable + to the mind.</p> + + <p><a name="sect_XXXIX_6_2">2</a>. A forceable argument, which shews the + necessity of pleasurable sensation to copulation, is, that the act cannot + be performed without it; it is easily interrupted by the pain of fear or + bashfulness; and no efforts of volition or of irritation can effect this + process, except such as induce pleasurable ideas or sensations. See Sect. + <a href="#sect_XXXIII_1_1">XXXIII. 1. 1</a>.</p> + + <p>A curious analogical circumstance attending hermaphrodite insects, as + snails and worms, still further illustrates this theory; if the snail or + worm could have impregnated itself, there might have been a saving of a + large male apparatus; but as this is not so ordered by nature, but each + snail and worm reciprocally receives and gives impregnation, it appears, + that a pleasurable excitation seems also to have been required.</p> + + <p>This wonderful circumstance of many insects being hermaphrodites, and + at the same time not having power to impregnate themselves, is attended + to by Dr. Lister, in his Exercitationes Anatom. de Limacibus, p. 145; + who, amongst many other final causes, which he adduces to account for it, + adds, ut tam tristibus et frigidis animalibus majori cum voluptate + perficiatur venus.</p> + + <p>There is, however, another final cause, to which this circumstance may + be imputed: it was observed above, that vegetable buds and bulbs, which + are produced without a mother, are always exact resemblances of their + parent; as appears in grafting fruit-trees, and in the flower-buds of the + dioiceous plants, which are always of the same sex on the same tree; + hence those hermaphrodite insects, if they could have produced young + without a mother, would not have been, capable of that change or + improvement, which is seen in all other animals, and in those vegetables, + which are procreated by the male embryon received and nourished by the + female. And it is hence probable, that if vegetables could only have been + produced by buds and bulbs, and not by sexual generation, that there + would not at this time have existed one thousandth part of their present + number of species; which have probably been originally mule-productions; + nor could any kind of improvement or change have happened to them, except + by the difference of soil or climate.</p> + + <p><a name="sect_XXXIX_6_3">3</a>. I conclude, that the imagination of + the male at the time of copulation, or at the time of the secretion of + the semen, may so affect this secretion by irritative or sensitive + association, as described in No. <a href="#sect_XXXIX_5_1">5. 1</a>. of + this section, as to cause the production of similarity of form and of + features, with the distinction of sex; as the motions of the chissel of + the turner imitate or correspond with those of the ideas of the artist. + It is not here to be understood, that the first living fibre, which is to + form an animal, is produced with any similarity of form to the future + animal; but with propensities, or appetences, which shall produce by + accretion of parts the similarity of form, feature, or sex, corresponding + to the imagination of the father.</p> + + <p>Our ideas are movements of the nerves of sense, as of the optic nerve + in recollecting visible ideas, suppose 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 the name of triangle. And it is a preceding + pleasurable sensation existing in my mind, which occasions me to produce + this particular motion of the retina, when no triangle is present. Now it + is probable, that the acting fibres of the ultimate terminations of the + secreting apertures of the vessels of the testes, are as fine as those of + the retina; and that they are liable to be thrown into that peculiar + action, which marks the sex of the secreted embryon, by sympathy with the + pleasurable motions of the nerves of vision or of touch; that is, with + certain ideas of imagination. From hence it would appear, that the world + has long been mistaken in ascribing 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 solely to the male. See Sect. <a + href="#sect_XII_3_3">XII. 3. 3</a>.</p> + + <p>It may be objected to this theory, that a man may be supposed to have + in his mind, the idea of the form and features of the female, rather than + his own, and therefore there should be a greater number of female births. + On the contrary, the general idea of our own form occurs to every one + almost perpetually, and is termed consciousness of our existence, and + thus may effect, that the number of males surpasses that of females. See + Sect. <a href="#sect_XV_3_4">XV. 3. 4</a>. and <a + href="#sect_XVIII_13">XVIII. 13</a>. And what further confirms this idea + is, that the male children most frequently resemble the father in form, + or feature, as well as in sex; and the female most frequently resemble + the mother, in feature, and form, as well as in sex.</p> + + <p>It may again be objected, if a female child sometimes resembles the + father, and a male child the mother, the ideas of the father, at the time + of procreation, must suddenly change from himself to the mother, at the + very instant, when the embryon is secreted or formed. This difficulty + ceases when we consider, that it is as easy 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 sphinx or + mermaid as easily and as distinctly 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 same time, by contact, or by + vision.</p> + + <p>I ask, in my turn, is the sex of the embryon produced by accident? + Certainly whatever is produced has a cause; but when this cause is too + minute for our comprehension, the effect is said in common language to + happen by chance, as in throwing a certain number on dice. Now what cause + can occasionally produce the male or female character of the embryon, but + the peculiar actions of those glands, which form the embryon? And what + can influence or govern these actions of the gland, but its associations + or catenations with other sensitive motions? Nor is this more + extraordinary, than that the catenations of irritative motions with the + apparent vibrations of objects at sea should produce sickness of the + stomach; or that a nauseous story should occasion vomiting.</p> + + <p><a name="sect_XXXIX_6_4">4</a>. An argument, which evinces the effect + of imagination on the first rudiment of the embryon, may be deduced from + the production of some peculiar monsters. Such, for instance, as those + which have two heads joined to one body, and those which have two bodies + joined to one head; of which frequent examples occur amongst our + domesticated quadrupeds, and poultry. It is absurd to suppose, that such + forms could exist in primordial germs, as explained in No. <a + href="#sect_XXXIX_4_4">IV. 4</a>. of this section. Nor is it possible, + that such deformities could be produced by the growth of two embryons, or + living filaments; which should afterwards adhere together; as the head + and tail part of different polypi are said to do (Blumenbach on + Generation, Cadel, London); since in that case one embryon, or living + filament, must have begun to form one part first, and the other another + part first. But such monstrous conformations become less difficult to + comprehend, when they are considered as an effect of the imagination, as + before explained, on the living filament at the time of its secretion; + and that such duplicature of limbs were produced by accretion of new + parts, in consequence of propensities, or animal appetencies thus + acquired from the male parent.</p> + + <p>For instance, I can conceive, if a turkey-cock should behold a rabbit, + or a frog, at the time of procreation, that it might happen, that a + forcible or even a pleasurable idea of the form of a quadruped might so + occupy his imagination, as to cause a tendency in the nascent filament to + resemble such a form, by the apposition of a duplicature of limbs. + Experiments on the production of mules and monsters would be worthy the + attention of a Spallanzani, and might throw much light upon this subject, + which at present must be explained by conjectural analogies.</p> + + <p>The wonderful effect of imagination, both in the male and female + parent, is shewn 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 observed + by Mr. Hunter, and mentioned before. To this should be added, that there + are some instances of men having had milk secreted in their breasts, and + who have given suck to children, as recorded by Mr. Buffon. This effect + of imagination, of both the male and female parent, seems to have been + attended to in very early times; Jacob is said not only to have placed + rods of trees, in part stripped of their bark, so as to appear spotted, + but also to have placed spotted lambs before the flocks, at the time of + their copulation. Genesis, chap. xxx. verse 40.</p> + + <p><a name="sect_XXXIX_6_5">5</a>. In respect to the imagination of the + mother, it is difficult to comprehend, how this can produce any + alteration in the fetus, except by affecting the nutriment laid up for + its first reception, as described in No. <a href="#sect_XXXIX_5_2">V. + 2</a>. of this section, or by affecting the nourishment or oxygenation + with which she supplies it afterwards. Perpetual anxiety may probably + affect the secretion of the liquor amnii into the uterus, as it enfeebles + the whole system; and sudden fear is a frequent cause of miscarriage; for + fear, contrary to joy, decreases for a time the action of the extremities + of the arterial system; hence sudden paleness succeeds, and a shrinking + or contraction of the vessels of the skin, and other membranes. By this + circumstance, I imagine, the terminations of the placental vessels are + detached from their adhesions, or insertions, into the membrane of the + uterus; and the death of the child succeeds, and consequent + miscarriage.</p> + + <p>Of this I recollect a remarkable instance, which could be ascribed to + no other cause, and which I shall therefore relate in few words. A + healthy young woman, about twenty years of age, had been about five + months pregnant, and going down into her cellar to draw some beer, was + frighted by a servant boy starting up from behind the barrel, where he + had concealed himself with design to alarm the maid-servant, for whom he + mistook his mistress. She came with difficulty up stairs, began to flood + immediately, and miscarried in a few hours. She has since borne several + children, nor ever had any tendency to miscarry of any of them.</p> + + <p><a name="sect_XXXIX_6_6">6</a>. In respect to the power of the + imagination of the male over the form, colour, and sex of the progeny, + the following instances have fallen under my observation, 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 himself have light hair and eyes; and their other + four children are like their parents. On observing this dissimilarity of + one child to the others he assured me, that he believed it was his own + imagination, that produced the difference; and related to me the + following story. He said, that when his lady lay in of her third child, + he became attached to a daughter of one of his inferior tenants, and + offered her a bribe for her favours in vain; and afterwards a greater + bribe, and was equally unsuccessful; that the form of this girl dwelt + much in his mind for some weeks, and that the next child, which was the + dark-ey'd young lady above mentioned, was exceedingly like, in both + features and colour, to the young woman who refused his addresses.</p> + + <p>To this instance I must add, that I have known two families, in which, + on account of an intailed estate in expectation, a male heir was most + eagerly desired by the father; and on the contrary, girls were produced + to the seventh in one, and to the ninth in another; and then they had + each of them a son. I conclude, that the great desire of a male heir by + the father produced rather a disagreeable than an agreeable sensation; + and that his ideas dwelt more on the fear of generating a female, than on + the pleasurable sensations or ideas of his own male form or organs at the + time of copulation, or of the secretion of the semen; and that hence the + idea of the female character was more present to his mind than that of + the male one; till at length in despair of generating a male these ideas + ceased, and those of the male character presided at the genial hour.</p> + + <p><a name="sect_XXXIX_6_7">7</a>. Hence I conclude, that the act of + generation cannot exist without being accompanied with ideas, and that a + man must have at that time either a general idea of his own male form, or + of the form of his male organs; or an idea of the female form, or of her + organs; and that this marks the sex, and the peculiar resemblances of the + child to either parent. From whence it 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 calipædia, or art of begetting beautiful children, + and of procreating either males or females, may be taught by affecting + the imagination of the male-parent; that is, by the fine extremities of + the seminal glands, imitating the actions of the organs of sense either + of sight or touch. But the manner of accomplishing this cannot be + unfolded with sufficient delicacy for the public eye; but may be worth + the attention of those, who are seriously interested in the procreation + of a male or female child.</p> + +<p class="center" style="margin-top: 2em;"><i>Recapitulation.</i></p> + + <p><a name="sect_XXXIX_7">VII</a>. <a name="sect_XXXIX_7_1">1</a>. A + certain quantity of nutritive particles are produced by the female parent + before impregnation, which require no further digestion, secretion, or + oxygenation. Such are seen in the unimpregnated eggs of birds, and in the + unimpregnated seed-vessels of vegetables.</p> + + <p><a name="sect_XXXIX_7_2">2</a>. A living filament is produced by the + male, which being inserted amidst these first nutritive particles, is + stimulated into action by them; and in consequence of this action, some + of the nutritive particles are embraced, and added to the original living + filament; in the same manner as common nutrition is performed in the + adult animal.</p> + + <p><a name="sect_XXXIX_7_3">3</a>. Then this new organization, or + additional part, becomes stimulated by the nutritive particles in its + vicinity, and sensation is now superadded to irritation; and other + particles are in consequence embraced, and added to the living filament; + as is seen in the new granulations of flesh in ulcers.</p> + + <p>By the power of association, or by irritation, the parts already + produced continue their motions, and new ones are added by sensation, as + above mentioned; and lastly by volition, which last sensorial power is + proved to exist in the fetus in its maturer age, because it has evidently + periods of activity and of sleeping; which last is another word for a + temporary suspension of volition.</p> + + <p>The original living filament may be conceived to possess a power of + repulsing the particles applied to certain parts of it, as well as of + embracing others, which stimulate other parts of it; as these powers + exist in different parts of the mature animal; thus the mouth of every + gland embraces the particles or fluid, which suits its appetency; and its + excretory duct repulses those particles, which are disagreeable to + it.</p> + + <p><a name="sect_XXXIX_7_4">4</a>. Thus the outline or miniature of the + new animal is produced gradually, but in no great length of time; because + the original nutritive particles require no previous preparation by + digestion, secretion, and oxygenation: but require simply the selection + and apposition, which is performed by the living filament. Mr. Blumenbach + says, that he possesses a human fetus of only five weeks old, which is + the size of a common bee, and has all the features of the face, every + finger, and every toe, complete; and in which the organs of generation + are distinctly seen. P. 76. In another fetus, whose head was not larger + than a pea, the whole of the basis of the skull with all its depressions, + apertures, and processes, were marked in the most sharp and distinct + manner, though without any ossification. Ib.</p> + + <p><a name="sect_XXXIX_7_5">5</a>. In some cases by the nutriment + originally deposited by the mother the filament acquires parts not + exactly similar to those of the father, as in the production of mules and + mulattoes. In other cases, the deficiency of this original nutriment + causes deficiencies of the extreme parts of the fetus, which are last + formed, as the fingers, toes, lips. In other cases, a duplicature of + limbs are caused by the superabundance 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 monsters, as those with two + heads, or with parts placed in wrong situations, seems to arise from the + imagination of the father being in some manner imitated by the extreme + vessels of the seminal glands; as the colours of the spots on eggs, and + the change of the colour of the hair and feathers of animals by + domestication, may be caused in the same manner by the imagination of the + mother.</p> + + <p><a name="sect_XXXIX_7_6">6</a>. The living filament is a part of the + father, and has therefore certain propensities, 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 + possesses such properties, as would render, by the apposition of + nutritious particles, the new fetus exactly similar to the father; as + occurs in the buds and bulbs of vegetables, and in the polypus, and tænia + or tape-worm. But as the first nutriment is supplied by the mother, and + therefore resembles such nutritive particles, as have been used for her + own nutriment or growth, the progeny takes in part of the likeness of the + mother.</p> + + <p>Other similarity of the excitability, or of the form of the male + parent, such as the broad or narrow shoulders, or such as constitute + certain hereditary diseases, as scrophula, epilepsy, insanity, have their + origin produced in one or perhaps two generations; as in the progeny of + those who drink much vinous spirits; and those hereditary propensities + cease again, as I have observed, if one or two sober generations succeed; + otherwise the family becomes extinct.</p> + + <p>This living filament from the father is also liable to have its + propensities, or appetencies, altered at the time of its production by + the imagination of the male parent; the extremities of the seminal glands + imitating the motions of the organs of sense; and thus the sex of the + embryon is produced; which may be thus made a male or a female by + affecting the imagination of the father at the time of impregnation. See + Sect. <a href="#sect_XXXIX_6_3">XXXIX. 6. 3</a>. and <a + href="#sect_XXXIX_6_7">7</a>.</p> + + <p><a name="sect_XXXIX_7_7">7</a>. After the fetus is thus completely + formed together with its umbilical vessels and placenta, it is now + supplied with a different kind of food, as appears by the difference of + consistency of the different parts of the white of the egg, and of the + liquor amnii, for it has now acquired organs for digestion or secretion, + and for oxygenation, though they are as yet feeble; which can in some + degree change, as well as select, the nutritive particles, which are now + presented to it. But may yet be affected by the deficiency of the + quantity of nutrition supplied by the mother, or by the degree of + oxygenation supplied to its placenta by the maternal blood.</p> + + <p>The augmentation of the complete fetus by additional particles of + nutriment is not accomplished by distention only, but by apposition 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 similar to their prototypes, and may be said + to be extended; but their extension must be conceived only as a necessary + consequence of the enlargement of all their parts by apposition of new + particles.</p> + + <p>Hence the new apposition of parts is not produced by capillary + attraction, because the whole is extended; whereas capillary attraction + would rather tend to bring the sides of flexible tubes together, and not + to distend them. Nor is it produced by chemical affinities, for then a + solution of continuity would succeed, as when sugar is dissolved in + water; but it is produced by an animal process, which is the consequence + of irritation, or sensation; and which may be termed animal + appetency.</p> + + <p>This is further evinced from experiments, which have been instituted + to shew, that a living muscle of an animal body requires greater force to + break it, than a similar muscle of a dead body. Which evinces, that + besides the attraction of cohesion, which all matter possesses, and + besides the chemical attractions of affinities, which hold many bodies + together, there is an animal adhesion, which adds vigour to these common + laws of the inanimate world.</p> + + <p><a name="sect_XXXIX_7_8">8</a>. At the nativity of the child it + deposits the placenta or gills, and by expanding its lungs acquires more + plentiful oxygenation from the currents of air, which it must now + continue perpetually to respire 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.</p> + + <p><a name="sect_XXXIX_7_9">9</a>. As the habitable parts of the earth + have been, and continue to be, perpetually increasing by the production + of sea-shells and corallines, and by the recrements of other animals, and + vegetables; so from the beginning of the existence of this terraqueous + globe, the animals, which inhabit it, have constantly improved, and are + still in a state of progressive improvement.</p> + + <p>This idea of the gradual generation of all things seems to have been + as familiar to the ancient philosophers as to the modern ones; and to + have given rise to the beautiful hieroglyphic figure of the <span + lang="el" title="proton ôon" >προτον + ωον</span>, or first great egg, produced by <font + class="sc">NIGHT</font>, that is, whose origin is involved in obscurity, + and animated by <span lang="el" title="eros" + >ερος</span>, that is, by D<font + class="sc">IVINE</font> L<font class="sc">OVE</font>; from whence + proceeded all things which exist.</p> + +<p class="center" style="margin-top: 2em;"><i>Conclusion.</i></p> + + <p><a name="sect_XXXIX_8">VIII</a>. <a name="sect_XXXIX_8_1">1</a>. Cause + and effect may be considered as the progression, or successive motions, + of the parts of the great system of Nature. The state of things at this + moment is the effect of the state of things, which existed in the + preceding moment; and the cause of the state of things, which shall exist + in the next moment.</p> + + <p>These causes and effects may be more easily comprehended, if motion be + considered as a change of the figure of a group of bodies, as proposed in + Sect. <a href="#sect_XIV_2_2">XIV. 2. 2</a>. inasmuch as our ideas of + visible or tangible objects are more distinct, than our abstracted ideas + of their motions. Now the change of the configuration of the system of + nature at this moment must be an effect of the preceding configuration, + for a change of configuration cannot exist without a previous + configuration; and the proximate cause of every effect must immediately + precede that effect. For example, a moving ivory ball could not proceed + onwards, unless it had previously began to proceed; or unless an impulse + had been previously given it; which previous motion or impulse + constitutes a part of the last situation of things.</p> + + <p>As the effects produced in this moment of time become causes in the + next, we may consider the progressive motions of objects as a chain of + causes only; whose first link proceeded from the great Creator, and which + have existed from the beginning of the created universe, and are + perpetually proceeding.</p> + + <p><a name="sect_XXXIX_8_2">2</a>. These causes may be conveniently + divided into two kinds, efficient and inert causes, according with the + two kinds of entity supposed to exist in the natural world, which may be + termed matter and spirit, as proposed in Sect. <a href="#sect_I">I</a>. + and further treated of in Sect. <a href="#sect_XIV">XIV</a>. The + efficient causes of motion, or new configuration, consist either of the + principle of general gravitation, which actuates the sun and planets; or + of the principle of particular gravitation, as in electricity, magnetism, + heat; or of the principle of chemical affinity, as in combustion, + fermentation, combination; or of the principle of organic life, as in the + contraction of vegetable and animal fibres. The inert causes of motion, + or new configuration, consist of the parts of matter, which are + introduced within the spheres of activity of the principles above + described. Thus, when an apple falls on the ground, the principle of + gravitation is the efficient cause, and the matter of the apple the inert + cause. If a bar of iron be approximated to a magnet, it may be termed the + inert cause of the motion, which brings these two bodies into contact; + while the magnetic principle may be termed the efficient cause. In the + same manner the fibres, which constitute the retina, may be called the + inert cause of the motions of that organ in vision, while the sensorial + power may be termed the efficient cause.</p> + + <p><a name="sect_XXXIX_8_3">3</a>. Another more common distribution of + the perpetual chain of causes and effects, which constitute the motions, + or changing configurations, of the natural world, is into active and + passive. Thus, if a ball in motion impinges against another ball at rest, + and communicates its motion to it, the former ball is said to act, and + the latter to be acted upon. In this sense of the words a magnet is said + to attract iron; and the prick of a spur to stimulate a horse into + exertion; so that in this view of the works of nature all things may be + said either simply to exist, or to exist as causes, or to exist as + effects; that is, to exist either in an active or passive state.</p> + + <p>This distribution of objects, and their motions, or changes of + position, has been found so convenient for the purposes of common life, + that on this foundation rests the whole construction or theory of + language. The names of the things themselves are termed by grammarians + Nouns, and their modes of existence are termed Verbs. The nouns are + divided into substantives, which denote the principal things spoken of; + and into adjectives, which denote some circumstances, or less kinds of + things, belonging to the former. The verbs are divided into three kinds, + such as denote the existence of things simply, as, to be; or their + existence in an active state, as, to eat; or their existence in a passive + state, as, to be eaten. Whence it appears, that all languages consist + only of nouns and verbs, with their abbreviations for the greater + expedition of communicating our thoughts; as explained in the ingenious + work of Mr. Horne Tooke, who has unfolded by a single flash of light the + whole theory of language, which had so long lain buried beneath the + learned lumber of the schools. Diversions of Purley. Johnson. London.</p> + + <p><a name="sect_XXXIX_8_4">4</a>. A third division of causes has been + into proximate and remote; these have been much spoken of by the writers + on medical subjects, but without sufficient precision. If to proximate + and remote causes we add proximate and remote effects, we shall include + four links of the perpetual chain of causation; which will be more + convenient for the discussion of many philosophical subjects.</p> + + <p>Thus if a particle of chyle be applied to the mouth of a lacteal + vessel, it may be termed the remote cause of the motions of the fibres, + which compose the mouth of that lacteal vessel; the sensorial power is + the proximate cause; the contraction of the fibres of the mouth of the + vessel is the proximate effect; and their embracing the particle of chyle + is the remote effect; and these four links of causation constitute + absorption.</p> + + <p>Thus when we attend to the rising sun, first the yellow rays of light + stimulate the sensorial power residing in the extremities of the optic + nerve, this is the remote cause. 2. The sensorial power is excited into a + state of activity, this is the proximate cause. 3. The fibrous + extremities of the optic nerve are contracted, this is the proximate + effect. 4. A pleasurable or painful sensation is produced in consequence + of the contraction of these fibres of the optic nerve, this is the remote + effect; and these four links of the chain of causation constitute the + sensitive idea, or what is commonly termed the sensation of the rising + sun.</p> + + <p>5. Other causes have been announced by medical writers under the names + of causa procatarctica, and causa proegumina, and causa sine quâ non. All + which are links more or less distant of the chain of remote causes.</p> + + <p>To these must be added the final cause, so called by many authors, + which means the motive, for the accomplishment of which the preceding + chain of causes was put into action. The idea of a final cause, + therefore, includes that of a rational mind, which employs means to + effect its purposes; thus the desire of preserving himself from the pain + of cold, which he has frequently experienced, induces the savage to + construct his hut; the fixing stakes into the ground for walls, branches + of trees for rafters, and turf for a cover, are a series of successive + voluntary exertions; which are so many means to produce a certain effect. + This effect of preserving himself from cold, is termed the final cause; + the construction of the hut is the remote effect; the action of the + muscular fibres of the man, is the proximate effect; the volition, or + activity of desire to preserve himself from cold, is the proximate cause; + and the pain of cold, which excited that desire, is the remote cause.</p> + + <p>6. This perpetual chain of causes and effects, whose first link is + rivetted to the throne of G<font class="sc">OD</font>, divides itself + into innumerable diverging branches, which, like the nerves arising from + the brain, permeate the most minute and most remote extremities of the + system, diffusing motion and sensation to the whole. As every cause is + superior in power to the effect, which it has produced, so our idea of + the power of the Almighty Creator becomes more elevated and sublime, as + we trace the operations of nature from cause to cause, climbing up the + links of these chains of being, till we ascend to the Great Source of all + things.</p> + + <p>Hence the modern discoveries in chemistry and in geology, by having + traced the causes of the combinations of bodies to remoter origins, as + well as those in astronomy, which dignify the present age, contribute to + enlarge and amplify our ideas of the power of the Great First Cause. And + had those ancient philosophers, who contended that the world was formed + from atoms, ascribed their combinations to certain immutable properties + received from the hand of the Creator, such as general gravitation, + chemical affinity, or animal appetency, instead of ascribing them to a + blind chance; the doctrine of atoms, as constituting or composing the + material world by the variety of their combinations, so far from leading + the mind to atheism, would strengthen the demonstration of the existence + of a Deity, as the first cause of all things; because the analogy + resulting from our perpetual experience of cause and effect would have + thus been exemplified through universal nature.</p> + + <p><i>The heavens declare the glory of </i>G<font + class="sc">OD</font><i>, and the firmament sheweth his handywork! One day + telleth another, and one night certifieth another; they have neither + speech nor language, yet their voice is gone forth into all lands, and + their words into the ends of the world. Manifold are thy works, </i>O + L<font class="sc">ORD</font>!<i> in wisdom hast thou made them all.</i> + Psal. xix. civ.</p> + + <br clear="all" /> +<hr /> + +<h3>SECT. <a name="sect_XL">XL</a>.</h3> + +<blockquote class="b1"> + + <p>On the OCULAR SPECTRA of Light and Colours, by Dr. R. W. Darwin, of + Shrewsbury. Reprinted, by Permission, from the Philosophical + Transactions, Vol. LXXVI. p. 313.</p> + + <p><i>Spectra of four kinds.</i> <a href="#sect_XL_1">1</a>. <i>Activity + of the retina in vision.</i> <a href="#sect_XL_2">2</a>. <i>Spectra from + defect of sensibility.</i> <a href="#sect_XL_3">3</a>. <i>Spectra from + excess of sensibility</i>. <a href="#sect_XL_4">4</a>. <i>Of direct + ocular spectra.</i> <a href="#sect_XL_5">5</a>. <i>Greater stimulus + excites the retina into spasmodic action.</i> <a href="#sect_XL_6">6</a>. + <i>Of reverse ocular spectra.</i> <a href="#sect_XL_7">7</a>. <i>Greater + stimulus excites the retina into various successive spasmodic + actions.</i> <a href="#sect_XL_8">8</a>. <i>Into fixed spasmodic + action.</i> <a href="#sect_XL_9">9</a>. <i>Into temporary paralysis.</i> + <a href="#sect_XL_10">10</a>. <i>Miscellaneous remarks;</i> <a + href="#sect_XL_10_1">1</a>. <i>Direct and reverse spectra at the same + time. A spectral halo. Rule to predetermine the colours of spectra.</i> + <a href="#sect_XL_10_2">2</a>. <i>Variation of spectra from extraneous + light.</i> <a href="#sect_XL_10_3">3</a>. <i>Variation of spectra in + number, figure, and remission.</i> <a href="#sect_XL_10_4">4</a>. + <i>Circulation of the blood in the eye is visible.</i> <a + href="#sect_XL_10_5">5</a>. <i>A new way of magnifying objects. + Conclusion.</i></p> + +</blockquote> + + <p>When any one has long and attentively looked at a bright object, as at + the setting sun, on closing his eyes, or removing them, an image, which + resembles in form the object he was attending to, continues some time to + be visible; this appearance in the eye we shall call the ocular spectrum + of that object.</p> + + <p>These ocular spectra are of four kinds: 1st, Such as are owing to a + less sensibility of a defined part of the retina; or <i>spectra from + defect of sensibility.</i> 2d, Such as are owing to a greater sensibility + of a defined part of the retina; or <i>spectra from excess of + sensibility</i>. 3d, Such as resemble their object in its colour as well + as form; which may be termed <i>direct ocular spectra</i>. 4th, Such as + are of a colour contrary to that of their object; which may be termed + <i>reverse ocular spectra</i>.</p> + + <p>The laws of light have been most successfully explained by the great + Newton, and the perception of visible objects has been ably investigated + by the ingenious Dr. Berkeley and M. Malebranche; but these minute + phenomena of vision have yet been thought reducible to no theory, though + many philosophers have employed a considerable degree of attention upon + them: among these are Dr. Jurin, at the end of Dr. Smith's Optics; M. + Æpinus, in the Nov. Com. Petropol. V. 10.; M. Beguelin, in the Berlin + Memoires, V. II. 1771; M. d'Arcy, in the Histoire de l'Acad. des Scienc. + 1765; M. de la Hire; and, lastly, the celebrated M. de Buffon, in the + Memoires de l'Acad. des Scien. who has termed them accidental colours, as + if subjected to no established laws, Ac. Par. 1743. M. p. 215.</p> + + <p>I must here apprize the reader, that it is very difficult for + different people to give the same names to various shades of colours; + whence, in the following pages, something must be allowed, if on + repeating the experiments the colours here mentioned should not + accurately correspond with his own names of them.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_1">I</a>. <i>Activity of the Retina in Vision.</i></p> + + <p>From the subsequent experiments it appears, that the retina is in an + active not in a passive state during the existence of these ocular + spectra; and it is thence to be concluded, that all vision is owing to + the activity of this organ.</p> + + <p><a name="sect_XL_1_1">1</a>. Place a piece of red silk, about an inch + in diameter, as in plate 1, at Sect. <a href="#sect_III_1">III. 1</a>., + on a sheet of white paper, in a strong light; look steadily upon it from + about the distance of half a yard for a minute; then closing your eyelids + cover them with your hands, and a green spectrum will be seen in your + eyes, resembling in form the piece of red silk: after some time, this + spectrum will disappear and shortly reappear; and this alternately three + or four times, if the experiment is well made, till at length it vanishes + entirely.</p> + + <p><a name="sect_XL_1_2">2</a>. Place on a sheet of white paper a + circular piece of blue silk, about four inches in diameter, in the + sunshine; cover the center of this with a circular piece of yellow silk, + about three inches in diameter; and the center of the yellow silk with a + circle of pink silk, about two inches in diameter; and the center of the + pink silk with a circle of green silk, about one inch in diameter; and + the centre of this with a circle of indigo, about half an inch in + diameter; make a small speck with ink in the very center of the whole, as + in plate 3, at Sect. <a href="#sect_III_3_6">III. 3. 6</a>.; look + steadily for a minute on this central spot, and then closing your eyes, + and applying your hand at about an inch distance before them, so as to + prevent too much or too little light from passing through the eyelids, + you will see the most beautiful circles of colours that imagination can + conceive, which are most resembled by the colours occasioned by pouring a + drop or two of oil on a still lake in a bright day; but these circular + irises of colours are not only different from the colours of the silks + above mentioned, but are at the same time perpetually changing as long as + they exist.</p> + + <p><a name="sect_XL_1_3">3</a>. When any one in the dark presses either + corner of his eye with his finger, and turns his eye away from his + finger, he will see a circle of colours like those in a peacock's tail: + and a sudden flash of light is excited in the eye by a stroke on it. + (Newton's Opt. Q. 16.)</p> + + <p><a name="sect_XL_1_4">4</a>. When any one turns round rapidly on one + foot, till he becomes dizzy, and falls upon the ground, the spectra of + the ambient objects continue to present themselves in rotation, or appear + to librate, and he seems to behold them for some time still in + motion.</p> + + <p>From all these experiments it appears, that the spectra in the eye are + not owing to the mechanical impulse of light impressed on the retina, nor + to its chemical combination with that organ, nor to the absorption and + emission of light, as is observed in many bodies; for in all these cases + the spectra must either remain uniformly, or gradually diminish; and + neither their alternate pretence and evanescence as in the first + experiment, nor the perpetual changes of their colours as in the second, + nor the flash of light or colours in the pressed eye as in the third, nor + the rotation or libration of the spectra as in the fourth, could + exist.</p> + + <p>It is not absurd to conceive, that the retina may be stimulated into + motion, as well as the red and white muscles which form our limbs and + vessels; since it consists of fibres, like those, intermixed with its + medullary substance. To evince this structure, the retina of an ox's eye + was suspended in a glass of warm water, and forcibly torn in a few + places; the edges of these parts appeared jagged and hairy, and did not + contract, and become smooth like simple mucus, when it is distended till + it breaks; which shews that it consists of fibres; and that its fibrous + construction became still more distinct to the sight, by adding some + caustic alkali to the water, as the adhering mucus was first eroded, and + the hair-like fibres remained floating in the vessel. Nor does the degree + of transparency of the retina invalidate the evidence of its fibrous + structure, since Leeuwenhoek has shewn that the crystalline humour itself + consists of fibres. (Arcana Naturæ, V. 1. p. 70.)</p> + + <p>Hence it appears, that as the muscles have larger fibres intermixed + with a smaller quantity of nervous medulla, the organ of vision has a + greater quantity of nervous medulla intermixed with smaller fibres; and + it is probable that the locomotive muscles, as well as the vascular ones, + of microscopic animals have much greater tenuity than these of the + retina.</p> + + <p>And besides the similar laws, which will be shewn in this paper to + govern alike the actions of the retina and of the muscles, there are many + other analogies which exist between them. They are both originally + excited into action by irritations, both are nearly in the same quantity + of time, are alike strengthened or fatigued by exertion, are alike + painful if excited into action when they are in an inflamed state, are + alike liable to paralysis, and to the torpor of old age.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_2">II</a>. O<font class="sc">F SPECTRA FROM DEFECT OF SENSIBILITY</font>.</p> + +<blockquote class="b1"> + + <p><i>The retina is not so easily excited into action by less irritation + after having been lately subjected to greater.</i></p> + +</blockquote> + + <p><a name="sect_XL_2_1">1</a>. When any one passes from the bright + daylight into a darkened room, the irises of his eyes expand themselves + to their utmost extent in a few seconds of time; but it is very long + before the optic nerve, after having been stimulated by the greater light + of the day, becomes sensible of the less degree of it in the room; and, + if the room is not too obscure, the irises will again contract themselves + in some degree, as the sensibility of the retina returns.</p> + + <p><a name="sect_XL_2_2">2</a>. Place about half an inch square of white + paper on a black hat, and looking steadily on the center of it for a + minute, remove your eyes to a sheet of white paper; and after a second or + two a dark square will be seen on the white paper, which will continue + some time. A similar dark square will be seen in the closed eye, if light + be admitted through the eyelids.</p> + + <p>So after looking at any luminous object of a small size, as at the + sun, for a short time, so as not much to fatigue the eyes, this part of + the retina becomes less sensible to smaller quantities of light; hence, + when the eyes are turned on other less luminous parts of the sky, a dark + spot is seen resembling the shape of the sun, or other luminous object + which we last beheld. This is the source of one kind of the dark-coloured + <i>muscæ volitantes</i>. If this dark spot lies above the center of the + eye, we turn our eyes that way, expecting to bring it into the center of + the eye, that we may view it more distinctly; and in this case the dark + spectrum seems to move upwards. If the dark spectrum is found beneath the + centre of the eye, we pursue it from the same motive, and it seems to + move downwards. This has given rise to various conjectures of something + floating in the aqueous humours of the eyes; but whoever, in attending to + these spots, keeps his eyes unmoved by looking steadily at the corner of + a cloud, at the same time that he observes the dark spectra, will be + thoroughly convinced, that they have no motion but what is given to them + by the movement of our eyes in pursuit of them. Sometimes the form of the + spectrum, when it has been received from a circular luminous body, will + become oblong; and sometimes it will be divided into two circular + spectra, which is not owing to our changing the angle made by the two + optic axises, according to the distance of the clouds or other bodies to + which the spectrum is supposed to be contiguous, but to other causes + mentioned in No. <a href="#sect_XL_10_3">X. 3</a>. of this section. The + apparent size of it will also be variable according to its supposed + distance.</p> + + <p>As these spectra are more easily observable when our eyes are a little + weakened by fatigue, it has frequently happened, that people of delicate + constitutions have been much alarmed at them, fearing a beginning decay + of their sight, and have thence fallen into the hands of ignorant + oculists; but I believe they never are a prelude to any other disease of + the eye, and that it is from habit alone, and our want of attention to + them, that we do not see them on all objects every hour of our lives. But + as the nerves of very weak people lose their sensibility, in the same + manner as their muscles lose their activity, by a small time of exertion, + it frequently happens, that sick people in the extreme debility of fevers + are perpetually employed in picking something from the bed-clothes, + occasioned by their mistaking the appearance of these <i>muscæ + volitantes</i> in their eyes. Benvenuto Celini, an Italian artist, a man + of strong abilities, relates, that having passed the whole night on a + distant mountain with some companions and a conjurer, and performed many + ceremonies to raise the devil, on their return in the morning to Rome, + and looking up when the sun began to rise, they saw numerous devils run + on the tops of the houses, as they passed along; so much were the spectra + of their weakened eyes magnified by fear, and made subservient to the + purposes of fraud or superstition. (Life of Ben. Celini.)</p> + + <p><a name="sect_XL_2_3">3</a>. Place a square inch of white paper on a + large piece of straw-coloured silk; look steadily some time on the white + paper, and then move the centre of your eyes on the silk, and a spectrum + of the form of the paper will appear on the silk, of a deeper yellow than + the other part of it: for the central part of the retina, having been + some time exposed to the stimulus of a greater quantity of white light, + is become less sensible to a smaller quantity of it, and therefore sees + only the yellow rays in that part of the straw-coloured silk.</p> + + <p>Facts similar to these are observable in other parts of our system: + thus, if one hand be made warm, and the other exposed to the cold, and + then both of them immersed in subtepid water, the water is perceived warm + to one hand, and cold to the other; and we are not able to hear weak + sounds for some time after we have been exposed to loud ones; and we feel + a chilliness on coming into an atmosphere of temperate warmth, after + having been some time confined in a very warm room: and hence the + stomach, and other organs of digestion, of those who have been habituated + to the greater stimulus of spirituous liquor, are not excited into their + due action by the less stimulus of common food alone; of which the + immediate consequence is indigestion and hypochondriacism.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_3">III</a>. O<font class="sc">F SPECTRA FROM EXCESS OF SENSIBILITY</font>.</p> + +<blockquote class="b1"> + + <p><i>The retina is more easily excited into action by greater irritation + after having been lately subjected to less.</i></p> + +</blockquote> + + <p><a name="sect_XL_3_1">1</a>. If the eyes are closed, and covered + perfectly with a hat, for a minute or two, in a bright day; on removing + the hat a red or crimson light is seen through the eyelids. In this + experiment the retina, after being some time kept in the dark, becomes so + sensible to a small quantity of light, as to perceive distinctly the + greater quantity of red rays than of others which pass through the + eyelids. A similar coloured light is seen to pass through the edges of + the fingers, when the open hand is opposed to the flame of a candle.</p> + + <p><a name="sect_XL_3_2">2</a>. If you look for some minutes steadily on + a window in the beginning of the evening twilight, or in a dark day, and + then move your eyes a little, so that those parts of the retina, on which + the dark frame-work of the window was delineated, may now fall on the + glass part of it, many luminous lines, representing the frame-work, will + appear to lie across the glass panes: for those parts of the retina, + which were before least stimulated by the dark frame-work, are now more + sensible to light than the other parts of the retina which were exposed + to the more luminous parts of the window,</p> + + <p><a name="sect_XL_3_3">3</a>. Make with ink on white paper a very black + spot, about half an inch in diameter, with a tail about an inch in + length, so as to represent a tadpole, as in plate 2, at Sect. <a + href="#sect_III_3_3">III. 3. 3</a>.; look steadily for a minute on this + spot, and, on moving the eye a little, the figure of the tadpole will be + seen on the white part of the paper, which figure of the tadpole will + appear whiter or more luminous than the other parts of the white paper; + for the part of the retina on which the tadpole was delineated, is now + more sensible to light, than the other parts of it, which were exposed to + the white paper. This experiment is mentioned by Dr. Irwin, but is not by + him ascribed to the true cause, namely, the greater sensibility of that + part of the retina which has been exposed to the black spot, than of the + other parts which had received the white field of paper, which is put + beyond a doubt by the next experiment.</p> + + <p><a name="sect_XL_3_4">4</a>. On closing the eyes after viewing the + black spot on the white paper, as in the foregoing experiment, a red spot + is seen of the form of the black spot: for that part of the retina, on + which the black spot was delineated, being now more sensible to light + than the other parts of it, which were exposed to the white paper, is + capable of perceiving the red rays which penetrate the eyelids. If this + experiment be made by the light of a tallow candle, the spot will be + yellow instead of red; for tallow candles abound much with yellow light, + which passes in greater quantity and force through the eyelids than blue + tight; hence the difficulty of distinguishing blue and green by this kind + of candle light. The colour of the spectrum may possibly vary in the + daylight, according to the different colour of the meridian or the + morning or evening light.</p> + + <p>M. Beguelin, in the Berlin Memoires, V. II. 1771, observes, that, when + he held a book so that the sun shone upon his half-closed eyelids, the + black letters, which he had long inspected, became red, which must have + been thus occasioned. Those parts of the retina which had received for + some time the black letters, were so much more sensible than those parts + which had been opposed to the white paper, that to the former the red + light, which passed through the eyelids, was perceptible. There is a + similar story told, I think, in de Voltaire's Historical Works, of a Duke + of Tuscany, who was playing at dice with the general of a foreign army, + and, believing he saw bloody spots upon the dice, portended dreadful + events, and retired in confusion. The observer, after looking for a + minute on the black spots of a die, and carelessly closing his eyes, on a + bright day; would see the image of a die with red spots upon it, as above + explained.</p> + + <p><a name="sect_XL_3_5">5</a>. On emerging from a dark cavern, where we + have long continued, the light of a bright day becomes intolerable to the + eye for a considerable time, owing to the excess of sensibility existing + in the eye, after having been long exposed to little or no stimulus. This + occasions us immediately to contract the iris to its smallest aperture, + which becomes again gradually dilated, as the retina becomes accustomed + to the greater stimulus of the daylight.</p> + + <p>The twinkling of a bright star, or of a distant candle in the night, + is perhaps owing to the same cause. While we continue to look upon these + luminous objects, their central parts gradually appear paler, owing to + the decreasing sensibility of the part of the retina exposed to their + light; whilst, at the same time, by the unsteadiness of the eye, the + edges of them are perpetually falling on parts of the retina that were + just before exposed to the darkness of the night, and therefore tenfold + more sensible to light than the part on which the star or candle had been + for some time delineated. This pains the eye in a similar manner as when + we come suddenly from a dark room into bright daylight, and gives the + appearance of bright scintillations. Hence the stars twinkle most when + the night is darkest, and do not twinkle through telescopes, as observed + by Musschenbroeck; and it will afterwards be seen why this twinkling is + sometimes of different colours when the object is very bright, as Mr. + Melvill observed in looking at Sirius. For the opinions of others on this + subject, see Dr. Priestley's valuable History of Light and Colours, p. + 494.</p> + + <p>Many facts observable in the animal system are similar to these; as + the hot glow occasioned by the usual warmth of the air, or our clothes, + on coming out of a cold bath; the pain of the fingers on approaching the + fire after having handled snow; and the inflamed heels from walking in + snow. Hence those who have been exposed to much cold have died on being + brought to a fire, or their limbs have become so much inflamed as to + mortify. Hence much food or wine given suddenly to those who have almost + perished by hunger has destroyed them; for all the organs of the famished + body are now become so much more irritable to the stimulus of food and + wine, which they have long been deprived of, that inflammation is + excited, which terminates in gangrene or fever.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_4">IV</a>. O<font class="sc">F DIRECT OCULAR SPECTRA</font>.</p> + +<blockquote class="b1"> + + <p><i>A quantity of stimulus somewhat greater than natural excites the + retina into spasmodic action, which ceases in a few seconds.</i></p> + +</blockquote> + + <p>A certain duration and energy of the stimulus of light and colours + excites the perfect action of the retina in vision; for very quick + motions are imperceptible to us, as well as very slow ones, as the + whirling of a top, or the shadow on a sun-dial. So perfect darkness does + not affect the eye at all; and excess of light produces pain, not + vision.</p> + + <p><a name="sect_XL_4_1">1</a>. When a fire-coal is whirled round in the + dark, a lucid circle remains a considerable time in the eye; and that + with so much vivacity of light, that it is mistaken for a continuance of + the irritation of the object. In the same manner, when a fiery meteor + shoots across the night, it appears to leave a long lucid train behind + it, part of which, and perhaps sometimes the whole, is owing to the + continuance of the action of the retina after having been thus vividly + excited. This is beautifully illustrated by the following experiment: fix + a paper sail, three or four inches in diameter, and made like that of a + smoke jack, on a tube of pasteboard; on looking through the tube at a + distant prospect, some disjointed parts of it will be seen through the + narrow intervals between the sails; but as the fly begins to revolve, + these intervals appear larger; and when it revolves quicker, the whole + prospect is seen quite as distinct as if nothing intervened, though less + luminous.</p> + + <div class="figright" style="width:25%;"> + <a href="images/fig3.png"><img width="100%" src="images/fig3.png" + alt="Fig. 3." /></a> + Fig. 3. + </div> + <p><a name="sect_XL_4_2">2</a>. Look through a dark tube, about half a + yard long, at the area of a yellow circle of half an inch diameter, lying + upon a blue area of double that diameter, for half a minute; and on + closing your eyes the colours of the spectrum will appear similar to the + two areas, as in fig. 3.; but if the eye is kept too long upon them, the + colours of the spectrum will be the reverse of those upon the paper, that + is, the internal circle will become blue, and the external area yellow; + hence some attention is required in making this experiment.</p> + + <p><a name="sect_XL_4_3">3</a>. Place the bright flame of a spermaceti + candle before a black object in the night; look steadily at it for a + short time, till it is observed to become somewhat paler; and on closing + the eyes, and covering them carefully, but not so as to compress them, + the image of the blazing candle will continue distinctly to be + visible.</p> + + <p><a name="sect_XL_4_4">4</a>. Look steadily, for a short time, at a + window in a dark day, as in Exp. 2. Sect. <a href="#sect_XL_3">III</a>. + and then closing your eyes, and covering them with your hands, an exact + delineation of the window remains for some time visible in the eye. This + experiment requires a little practice to make it succeed well; since, if + the eyes are fatigued by looking too long on the window, or the day be + too bright, the luminous parts of the window will appear dark in the + spectrum, and the dark parts of the frame-work will appear luminous, as + in Exp. 2. Sect. <a href="#sect_XL_3">III</a>. And it is even difficult + for many, who first try this experiment, to perceive the spectrum at all; + for any hurry of mind, or even too great attention to the spectrum + itself, will disappoint them, till they have had a little experience in + attending to such small sensations.</p> + + <p>The spectra described in this section, termed direct ocular spectra, + are produced without much fatigue of the eye; the irritation of the + luminous object being soon withdrawn, or its quantity of light being not + so great as to produce any degree of uneasiness in the organ of vision; + which distinguishes them from the next class of ocular spectra, which are + the consequence of fatigue. These direct spectra are best observed in + such circumstances that no light, but what comes from the object, can + fall upon the eye; as in looking through a tube, of half a yard long, and + an inch wide, at a yellow paper on the side of a room, the direct + spectrum was easily produced on closing the eye without taking it from + the tube; but if the lateral light is admitted through the eyelids, or by + throwing the spectrum on white paper, it becomes a reverse spectrum, as + will be explained below.</p> + + <p>The other senses also retain for a time the impressions that have been + made upon them, or the actions they have been excited into. So if a hard + body is pressed upon the palm of the hand, as is practised in tricks of + legerdemain, it is not easy to distinguish for a few seconds whether it + remains or is removed; and tastes continue long to exist vividly in the + mouth, as the smoke of tobacco, or the taste of gentian, after the sapid + material is withdrawn.</p> + +<blockquote class="b1"> + + <p><a name="sect_XL_5">V</a>. <i>A quantity of stimulus somewhat greater + than the last mentioned excites the retina into spasmodic action, which + ceases and recurs alternately.</i></p> + +</blockquote> + + <p><a name="sect_XL_5_1">1</a>. On looking for a time on the setting sun, + so as not greatly to fatigue the sight, a yellow spectrum is seen when + the eyes are closed and covered, which continues for a time, and then + disappears and recurs repeatedly before it entirely vanishes. This yellow + spectrum of the sun when the eyelids are opened becomes blue; and if it + is made to fall on the green grass, or on other coloured objects, it + varies its own colour by an intermixture of theirs, as will be explained + in another place.</p> + + <p><a name="sect_XL_5_2">2</a>. Place a lighted spermaceti candle in the + night about one foot from your eye, and look steadily on the centre of + the flame, till your eye becomes much more fatigued than in Sect. <a + href="#sect_XL_4">IV</a>. Exp. 3.; and on closing your eyes a reddish + spectrum will be perceived, which will cease and return alternately.</p> + + <p>The action of vomiting in like manner ceases, and is renewed by + intervals, although the emetic drug is thrown up with the first effort: + so after-pains continue some time after parturition; and the alternate + pulsations of the heart of a viper are renewed for some time after it is + cleared from its blood.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_6">VI</a>. O<font class="sc">F REVERSE OCULAR SPECTRA</font>.</p> + +<blockquote class="b1"> + + <p><i>The retina, after having been excited into action by a stimulus + somewhat greater them the last mentioned falls into opposite spasmodic + action.</i></p> + +</blockquote> + + <p>The actions of every part of animal bodies may be advantageously + compared with each other. This strict analogy contributes much to the + investigation of truth; while those looser analogies, which compare the + phenomena of animal life with those of chemistry or mechanics, only serve + to mislead our inquiries.</p> + + <p>When any of our larger muscles have been in long or in violent action, + and their antagonists have been at the same time extended, as soon as the + action of the former ceases, the limb is stretched the contrary way for + our ease, and a pandiculation or yawning takes place.</p> + + <p>By the following observations it appears, that a similar circumstance + obtains in the organ of vision; after it has been fatigued by one kind of + action, it spontaneously falls into the opposite kind.</p> + + <p><a name="sect_XL_6_1">1</a>. Place a piece of coloured silk, about an + inch in diameter, on a sheet of white paper, about half a yard from your + eyes; look steadily upon it for a minute; then remove your eyes upon + another part of the white paper, and a spectrum will be seen of the form + of the silk thus inspected, but of a colour opposite to it. A spectrum + nearly similar will appear if the eyes are closed, and the eyelids shaded + by approaching the hand near them, so as to permit some, but to prevent + too much light falling on them.</p> + + <div class="poem"> + <div class="stanza"> + <p>Red silk produced a green spectrum.</p> + <p>Green produced a red one.</p> + <p>Orange produced blue.</p> + <p>Blue produced orange.</p> + <p>Yellow produced violet.</p> + <p>Violet produced yellow.</p> + </div> + </div> + <p>That in these experiments the colours of the spectra are the reverse + of the colours which occasioned them, may be seen by examining the third + figure in Sir Isaac Newton's Optics, L. II. p. 1, where those thin laminæ + of air, which reflected yellow, transmitted violet; those which reflected + red, transmitted a blue green; and so of the rest, agreeing with the + experiments above related.</p> + + <p><a name="sect_XL_6_2">2</a>. These reverse spectra are similar to a + colour, formed by a combination of all the primary colours except that + with which the eye has been fatigued in making the experiment: thus the + reverse spectrum of red must be such a green as would be produced by a + combination of all the other prismatic colours. To evince this fact the + following satisfactory experiment was made. The prismatic colours were + laid on a circular pasteboard wheel, about four inches in diameter, in + the proportions described in Dr. Priestley's History of Light and + Colours, pl. 12. fig. 83. except that the red compartment was entirely + left out, and the others proportionably extended so as to complete the + circle. Then, as the orange is a mixture of red and yellow, and as the + violet is a mixture of red and indigo, it became necessary to put yellow + on the wheel instead of orange, and indigo instead of violet, that the + experiment might more exactly quadrate with the theory it was designed to + establish or confute; because in gaining a green spectrum from a red + object, the eye is supposed to have become insensible to red light. This + wheel, by means of an axis, was made to whirl like a top; and on its + being put in motion, a green colour was produced, corresponding with + great exactness to the reverse spectrum of red.</p> + + <p><a name="sect_XL_6_3">3</a>. In contemplating any one or these reverse + spectra in the closed and covered eye, it disappears and re-appears + several times successively, till at length it entirely vanishes, like the + direct spectra in Sect. <a href="#sect_XL_5">V</a>.; but with this + additional circumstance, that when the spectrum becomes faint or + evanescent, it is instantly revived by removing the hand from before the + eyelids, so as to admit more light: because then not only the fatigued + part of the retina is inclined spontaneously to fall into motions of a + contrary direction, but being still sensible to all other rays of light, + except that with which it was lately fatigued, is by these rays at the + same time stimulated into those motions which form the reverse + spectrum.</p> + + <p>From these experiments there is reason to conclude, that the fatigued + part of the retina throws itself into a contrary mode of action, like + oscitation or pandiculation, as soon as the stimulus which has fatigued + it is withdrawn; and that it still remains sensible, that is, liable to + be excited into action by any other colours at the same time, except the + colour with which it has been fatigued.</p> + +<blockquote class="b1"> + + <p><a name="sect_XL_7">VII</a>. <i>The retina after having been excited + into action by a stimulus somewhat greater than the last mentioned falls + into various successive spasmodic actions.</i></p> + +</blockquote> + + <p><a name="sect_XL_7_1">1</a>. On looking at the meridian sun as long as + the eyes can well bear its brightness, the disk first becomes pale, with + a luminous crescent, which seems to librate from one edge of it to the + other, owing to the unsteadiness of the eye; then the whole phasis of the + sun becomes blue, surrounded with a white halo; and on closing the eyes, + and covering them with the hands, a yellow spectrum is seen, which in a + little time changes into a blue one.</p> + + <p>M. de la Hire observed, after looking at the bright sun, that the + impression in his eye first assumed a yellow appearance, and then green, + and then blue; and wishes to ascribe these appearances to some affection + of the nerves. (Porterfield on the Eye, Vol. I. p. 313.)</p> + + <p><a name="sect_XL_7_2">2</a>. After looking steadily on about an inch + square of pink silk, placed on white paper, in a bright sunshine, at the + distance of a foot from my eyes, and closing and covering my eyelids, the + spectrum of the silk was at first a dark green, and the spectrum of the + white paper became of a pink. The spectra then both disappeared; and then + the internal spectrum was blue; and then, after a second disappearance, + became yellow, and lastly pink, whilst the spectrum of the field varied + into red and green.</p> + + <p>These successions of different coloured spectra were not exactly the + same in the different experiments, though observed, as near as could be, + with the same quantity of light, and other similar circumstances; owing, + I suppose, to trying too many experiments at a time; so that the eye was + not quite free from the spectra of the colours which were previously + attended to.</p> + + <p>The alternate exertions of the retina in the preceding section + resembled the oscitation or pandiculation of the muscles, as they were + performed in directions contrary to each other, and were the consequence + of fatigue rather than of pain. And in this they differ from the + successive dissimilar exertions of the retina, mentioned in this section, + which resemble in miniature the more violent agitations of the limbs in + convulsive diseases, as epilepsy, chorea S. Viti, and opisthotonos; all + which diseases are perhaps, at first, the consequence of pain, and have + their periods afterwards established by habit.</p> + +<blockquote class="b1"> + + <p><a name="sect_XL_8">VIII</a>. <i>The retina, after having been excited + into action by a stimulus somewhat greater than the last mentioned falls + into a fixed spasmodic action, which continues for some days.</i></p> + +</blockquote> + + <p><a name="sect_XL_8_1">1</a>. After having looked long at the meridian + sun, in making some of the preceding experiments, till the disks faded + into a pale blue, I frequently observed a bright blue spectrum of the sun + on other objects all the next and the succeeding day, which constantly + occurred when I attended to it, and frequently when I did not previously + attend to it. When I closed and covered my eyes, this appeared of a dull + yellow; and at other times mixed with the colours of other objects on + which it was thrown. It may be imagined, that this part of the retina was + become insensible to white light, and thence a bluish spectrum became + visible on all luminous objects; but as a yellowish spectrum was also + seen in the closed and covered eye, there can remain no doubt of this + being the spectrum of the sun. A similar appearance was observed by M. + Æpinus, which he acknowledges he could give no account of. (Nov. Com. + Petrop. V. 10. p. 2. and 6.)</p> + + <p>The locked jaw, and some cataleptic spasms, are resembled by this + phenomenon; and from hence we may learn the danger to the eye by + inspecting very luminous objects too long a time.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_9">IX</a>. <i>A quantity of stimulus greater than the preceding induces a temporary +paralysis of the organ of vision.</i></p> + + <p><a name="sect_XL_9_1">1</a>. Place a circular piece of bright red + silk, about half an inch in diameter, on the middle of a sheet of white + paper; lay them on the floor in a bright sunshine, and fixing your eyes + steadily on the center of the red circle, for three or four minutes, at + the distance of four or six feet from the object, the red silk will + gradually become paler, and finally cease to appear red at all.</p> + + <p><a name="sect_XL_9_2">2</a>. Similar to these are many other animal + facts; as purges, opiates, and even poisons, and contagious matter, cease + to stimulate our system, after we have been habituated to their use. So + some people sleep undisturbed by a clock, or even by a forge hammer in + their neighbourhood: and not only continued irritations, but violent + exertions of any kind, are succeeded by temporary paralysis. The arm + drops down after violent action, and continues for a time useless; and it + is probable, that those who have perished suddenly in swimming, or in + scating on the ice, have owed their deaths to the paralysis, or extreme + fatigue, which succeeds every violent and continued exertion.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_10">X</a>. M<font class="sc">ISCELLANEOUS</font> R<font class="sc">EMARKS</font>.</p> + + <p>There were some circumstances occurred in making these experiments, + which were liable to alter the results of them, and which I shall here + mention for the assistance of others, who may wish to repeat them.</p> + + <p><a name="sect_XL_10_1">1</a>. <i>Of direct and inverse spectra + existing at the same time</i>; <i>of reciprocal direct spectra</i>; <i>of + a combination of direct and inverse spectra</i>; <i>of a spectral + halo</i>; <i>rules to pre-determine the colours of spectra</i>.</p> + + <p><i>a.</i> When an area, about six inches square, of bright pink Indian + paper, had been viewed on an area, about a foot square, of white writing + paper, the internal spectrum in the closed eye was green, being the + reverse spectrum of the pink paper; and the external spectrum was pink, + being the direct spectrum of the pink paper. The same circumstance + happened when the internal area was white, and external one pink; that + is, the internal spectrum was pink, and the external one green. All the + same appearances occurred when the pink paper was laid on a black + hat.</p> + + <p><i>b.</i> When six inches square of deep violet polished paper was + viewed on a foot square of white writing paper, the internal spectrum was + yellow, being the reverse spectrum of the violet paper, and the external + one was violet, being the direct spectrum of the violet paper.</p> + + <p><i>c.</i> When six inches square of pink paper was viewed on a foot + square of blue paper, the internal spectrum was blue, and the external + spectrum was pink; that is, the internal one was the direct spectrum of + the external object, and the external one was the direct spectrum of the + internal object, instead of their being each the reverse spectrum of the + objects they belonged to.</p> + + <p><i>d.</i> When six inches square of blue paper were viewed on a foot + square of yellow paper, the interior spectrum became a brilliant yellow, + and the exterior one a brilliant blue. The vivacity of the spectra was + owing to their being excited both by the stimulus of the interior and + exterior objects; so that the interior yellow spectrum was both the + reverse spectrum of the blue paper, and the direct one of the yellow + paper; and the exterior blue spectrum was both the reverse spectrum of + the yellow paper, and the direct one of the blue paper.</p> + + <p><i>e.</i> When the internal area was only a square half-inch of red + paper, laid on a square foot of dark violet paper, the internal spectrum + was green, with a reddish-blue halo. When the red internal paper was two + inches square, the internal spectrum was a deeper green, and the external + one redder. When the internal paper was six inches square, the spectrum + of it became blue, and the spectrum of the external paper was red.</p> + + <p><i>f.</i> When a square half-inch of blue paper was laid on a six-inch + square of yellow paper, the spectrum of the central paper in the closed + eye was yellow, incircled with a blue halo. On looking long on the + meridian sun, the disk fades into a pale blue surrounded with a whitish + halo.</p> + + <p>These circumstances, though they very much perplexed the experiments + till they were investigated, admit of a satisfactory explanation; for + while the rays from the bright internal object in exp. <i>a.</i> fall + with their full force on the center of the retina, and, by fatiguing that + part of it, induce the reverse spectrum, many scattered rays, from the + same internal pink paper, fall on the more external parts of the retina, + but not in such quantity as to occasion much fatigue, and hence induce + the direct spectrum of the pink colour in those parts of the eye. The + same reverse and direct spectra occur from the violet paper in exp. + <i>b.</i>: and in exp. <i>c.</i> the scattered rays from the central pink + paper produce a direct spectrum of this colour on the external parts of + the eye, while the scattered rays from the external blue paper produce a + direct spectrum of that colour on the central part of the eye, instead of + these parts of the retina falling reciprocally into their reverse + spectra. In exp. <i>d.</i> the colours being the reverse of each other, + the scattered rays from the exterior object falling on the central parts + of the eye, and there exciting their direct spectrum, at the same time + that the retina was excited into a reverse spectrum by the central + object, and this direct and reverse spectrum being of similar colour, the + superior brilliancy of this spectrum was produced. In exp. <i>e.</i> the + effect of various quantities of stimulus on the retina, from the + different respective sizes of the internal and external areas, induced a + spectrum of the internal area in the center of the eye, combined of the + reverse spectrum of that internal area and the direct one of the external + area, in various shades of colour, from a pale green to a deep blue, with + similar changes in the spectrum of the external area. For the same + reasons, when an internal bright object was small, as in exp. <i>f.</i> + instead of the whole of the spectrum of the external object being reverse + to the colour of the internal object, only a kind of halo, or radiation + of colour, similar to that of the internal object, was spread a little + way on the external spectrum. For this internal blue area being so small, + the scattered rays from it extended but a little way on the image of the + external area of yellow paper, and could therefore produce only a blue + halo round the yellow spectrum in the center.</p> + + <p>If any one should suspect that the scattered rays from the exterior + coloured object do not intermix with the rays from the interior coloured + object, and thus affect the central part of the eye, let him look through + an opake tube, about two feet in length, and an inch in diameter, at a + coloured wall of a room with one eye, and with the other eye naked; and + he will find, that by shutting out the lateral light, the area of the + wall seen through a tube appears as if illuminated by the sunshine, + compared with the other parts of it; from whence arises the advantage of + looking through a dark tube at distant paintings.</p> + + <p>Hence we may safely deduce the following rules to determine + before-hand the colours of all spectra. 1. The direct spectrum without + any lateral light is an evanescent representation of its object in the + unfatigued eye. 2. With some lateral light it becomes of a colour + combined of the direct spectrum of the central object, and of the + circumjacent objects, in proportion to their respective quantity and + brilliancy. 3. The reverse spectrum without lateral light is a + representation in the fatigued eye of the form of its objects, with such + a colour as would be produced by all the primary colours, except that of + the object. 4. With lateral light the colour is compounded of the reverse + spectrum of the central object, and the direct spectrum of the + circumjacent objects, in proportion to their respective quantity and + brilliancy.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_10_2">2</a>. <i>Variation and vivacity of the spectra occasioned by extraneous light.</i></p> + + <p>The reverse spectrum, as has been before explained, is similar to a + colour, formed by a combination of all the primary colours, except that + with which the eye has been fatigued in making the experiment: so the + reverse spectrum of red is such a green as would be produced by a + combination of all the other prismatic colours. Now it must be observed, + that this reverse spectrum of red is therefore the direct spectrum of a + combination of all the other prismatic colours, except the red; whence, + on removing the eye from a piece of red silk to a sheet of white paper, + the green spectrum, which is perceived, may either be called the reverse + spectrum of the red silk, or the direct spectrum of all the rays from the + white paper, except the red; for in truth it is both. Hence we see the + reason why it is not easy to gain a direct spectrum of any coloured + object in the day-time, where there is much lateral light, except of very + bright objects, as of the setting sun, or by looking through an opake + tube; because the lateral external light falling also on the central part + of the retina, contributes to induce the reverse spectrum, which is at + the same time the direct spectrum of that lateral light, deducting only + the colour of the central object which we have been viewing. And for the + same reason, it is difficult to gain the reverse spectrum, where there is + no lateral light to contribute to its formation. Thus, in looking through + an opake tube on a yellow wall, and closing my eye, without admitting any + lateral light, the spectra were all at first yellow; but at length + changed into blue. And on looking in the same manner on red paper, I did + at length get a green spectrum; but they were all at first red ones: and + the same after looking at a candle in the night.</p> + + <p>The reverse spectrum was formed with greater facility when the eye was + thrown from the object on a sheet of white paper, or when light was + admitted through the closed eyelids; because not only the fatigued part + of the retina was inclined spontaneously to fall into motions of a + contrary direction; but being still sensible to all other rays of light + except that with which it was lately fatigued, was by these rays + stimulated at the same time into those motions which form the reverse + spectrum. Hence, when, the reverse spectrum of any colour became faint, + it was wonderfully revived by admitting more light through the eyelids, + by removing the hand from before them: and hence, on covering the closed + eyelids, the spectrum would often cease for a time, till the retina + became sensible to the stimulus of the smaller quantity of light, and + then it recurred. Nor was the spectrum only changed in vivacity, or in + degree, by this admission of light through the eyelids; but it frequently + happened, after having viewed bright objects, that the spectrum in the + closed and covered eye was changed into a third spectrum, when light was + admitted through the eyelids: which third spectrum was composed of such + colours as could pass through the eyelids, except those of the object. + Thus, when an area of half an inch diameter of pink paper was viewed on a + sheet of white paper in the sunshine, the spectrum with closed and + covered eyes was green; but on removing the hands from before the closed + eyelids, the spectrum became yellow, and returned instantly again to + green, as often as the hands were applied to cover the eyelids, or + removed from them: for the retina being now insensible to red light, the + yellow rays passing through the eyelids in greater quantity than the + other colours, induced a yellow spectrum; whereas if the spectrum was + thrown on white paper, with the eyes open, it became only a lighter + green.</p> + + <p>Though a certain quantity of light facilitates the formation of the + reverse spectrum, a greater quantity prevents its formation, as the more + powerful stimulus excites even the fatigued parts of the eye into action; + otherwise we should see the spectrum of the last viewed object as often + as we turn our eyes. Hence the reverse spectra are best seen by gradually + approaching the hand near the closed eyelids to a certain distance only, + which must be varied with the brightness of the day, or the energy of the + spectrum. Add to this, that all dark spectra, as black, blue, or green, + if light be admitted through the eyelids, after they have been some time + covered, give reddish spectra, for the reasons given in Sect. <a + href="#sect_XL_3">III</a>. Exp. 1.</p> + + <p>From these circumstances of the extraneous light coinciding with the + spontaneous efforts of the fatigued retina to produce a reverse spectrum, + as was observed before, it is not easy to gain a direct spectrum, except + of objects brighter than the ambient light; such as a candle in the + night, the setting sun, or viewing a bright object through an opake tube; + and then the reverse spectrum is instantaneously produced by the + admission of some external light; and is as instantly converted again to + the direct spectrum by the exclusion of it. Thus, on looking at the + setting sun, on closing the eyes, and covering them, a yellow spectrum is + seen, which is the direct spectrum of the setting sun; but on opening the + eyes on the sky, the yellow spectrum is immediately changed into a blue + one, which is the reverse spectrum of the yellow sun, or the direct + spectrum of the blue sky, or a combination of both. And this is again + transformed into a yellow one on closing the eyes, and so reciprocally, + as quick as the motions of the opening and closing eyelids. Hence, when + Mr. Melvill observed the scintillations of the star Sirius to be + sometimes coloured, these were probably the direct spectrum of the blue + sky on the parts of the retina fatigued by the white light of the star. + (Essays Physical and Literary, p. 81. V. 2.)</p> + + <p>When a direct spectrum is thrown on colours darker than itself, it + mixes with them; as the yellow spectrum of the setting sun, thrown on the + green grass, becomes a greener yellow. But when a direct spectrum is + thrown on colours brighter than itself, it becomes instantly changed into + the reverse spectrum, which mixes with those brighter colours. So the + yellow spectrum of the setting sun thrown on the luminous sky becomes + blue, and changes with the colour or brightness of the clouds on which it + appears. But the reverse spectrum mixes with every kind of colour on + which it is thrown, whether brighter than itself or not; thus the reverse + spectrum, obtained by viewing a piece of yellow silk, when thrown on + white paper, was a lucid blue green; when thrown on black Turkey leather, + becomes a deep violet. And the spectrum of blue silk, thrown on white + paper, was a light yellow; on black silk was an obscure orange; and, the + blue spectrum, obtained from orange-coloured silk, thrown on yellow, + became a green.</p> + + <p>In these cases the retina is thrown into activity or sensation by the + stimulus of external colours, at the same time that it continues the + activity or sensation which forms the spectra; in the same manner as the + prismatic colours, painted on a whirling top, are seen to mix together. + When these colours of external objects are brighter than the direct + spectrum which is thrown upon them, they change it into the reverse + spectrum, like the admission of external light on a direct spectrum, as + explained above. When they are darker than the direct spectrum, they mix + with it, their weaker stimulus being inefficient to induce the reverse + spectrum.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_10_3">3</a>. <i>Variation of spectra in respect to number, and figure, and remission.</i></p> + + <div class="figright" style="width:25%;"> + <a href="images/fig4.png"><img width="100%" src="images/fig4.png" + alt="Fig. 4." /></a> + Fig. 4. + </div> + <p>When we look long and attentively at any object, the eye cannot always + be kept entirely motionless; hence, on inspecting a circular area of red + silk placed on white paper, a lucid crescent or edge is seen to librate + on one side or other of the red circle: for the exterior parts of the + retina sometimes falling on the edge of the central silk, and sometimes + on the white paper, are less fatigued with red light than the central + part of the retina, which is constantly, exposed to it; and therefore, + when they fall on the edge of the red silk, they perceive it more + vividly. Afterwards, when the eye becomes fatigued, a green spectrum in + the form of a crescent is seen to librate on one side or other of the + central circle, as by the unsteadiness of the eye a part of the fatigued + retina falls on the white paper; and as by the increasing fatigue of the + eye the central part of the silk appears paler, the edge on which the + unfatigued part of the retina occasionally falls will appear of a deeper + red than the original silk, because it is compared with the pale internal + part of it. M. de Buffon in making this experiment observed, that the red + edge of the silk was not only deeper coloured than the original silk; + but, on his retreating a little from it, it became oblong, and at length + divided into two, which must have been owing to his observing it either + before or behind the point of intersection of the two optic axises. Thus, + if a pen is held up before a distant candle, when we look intensely at + the pen two candles are seen behind it; when we look intensely at the + candle two pens are seen. If the sight be unsteady at the time of + beholding the sun, even though one eye only be used, many images of the + sun will appear, or luminous lines, when the eye is closed. And as some + parts of these will be more vivid than others, and some parts of them + will be produced nearer the center of the eye than others, these will + disappear sooner than the others; and hence the number and shape of these + spectra of the sun will continually vary, as long as they exist. The + cause of some being more vivid than others, is the unsteadiness of the + eye of the beholder, so that some parts of the retina have been longer + exposed to the sunbeams. That some parts of a complicated spectrum 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 center + of these circles, in a bright light, the spectrum of the external area + appears first in the closed eye, then the middle area, and lastly the + central one; and then the central one disappears, and the others in + inverted order. If concentric circles of more colours are added, it + produces the beautiful ever changing spectrum in Sect. <a + href="#sect_XL_1">I</a>. Exp. 2.</p> + + <p>From hence it would seem, that the center of the eye produces quicker + remissions of spectra, owing perhaps to its greater sensibility; that is, + to its more energetic exertions. These remissions of spectra bear some + analogy to the tremors of the hands, and palpitations of the heart, of + weak people: and perhaps a criterion of the strength of any muscle or + nerve may be taken from the time it can be continued in exertion.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_10_4">4</a>. <i>Variation of spectra in respect to brilliancy; the visibility of the circulation +of the blood in the eye.</i></p> + + <p>1. The meridian or evening light makes a difference in the colours of + some spectra; for as the sun descends, the red rays, which are less + refrangible by the convex atmosphere, abound in great quantity. Whence + the spectrum of the light parts of a window at this time, or early in the + morning, is red; and becomes blue either a little later or earlier; and + white in the meridian day; and is also variable from the colour of the + clouds or sky which are opposed to the window.</p> + + <p>2. All these experiments are liable to be confounded, if they are made + too soon after each other, as the remaining spectrum will mix with the + new ones. This is a very troublesome circumstance to painters, who are + obliged to look long upon the same colour; and in particular to those + whose eyes, from natural debility, cannot long, continue the same kind of + exertion. For the same reason, in making these experiments, the result + becomes much varied if the eyes, after viewing any object, are removed on + other objects for but an instant of time, before we close them to view + the spectrum; for the light from the object, of which we had only a + transient view, in the very time of closing our eyes acts as a stimulus + on the fatigued retina; and for a time prevents the defined spectrum from + appearing, or mixes its own spectrum with it. Whence, after the eyelids + are closed, either a dark field, or some unexpected colours, are beheld + for a few seconds, before the desired spectrum becomes distinctly + visible.</p> + + <p>3. The length of time taken up in viewing an object, of which we are + to observe the spectrum, makes a great difference in the appearance of + the spectrum, not only in its vivacity, but in its colour; as the direct + spectrum of the central object, or of the circumjacent ones, and also the + reverse spectra of both, with their various combinations, as well as the + time of their duration in the eye, and of their remissions or + alternations, depend upon the degree of fatigue the retina is subjected + to. The Chevalier d'Arcy constructed a machine by which a coal of fire + was whirled round in the dark, and found, that when a luminous body made + a revolution in eight thirds of time, it presented to the eye a complete + circle of fire; from whence he concludes, that the impression continues + on the organ about the seventh part of a second. (Mem. de l'Acad. des Sc. + 1765.) This, however, is only to be considered as the shortest time of + the duration of these direct spectra; since in the fatigued eye both the + direct and reverse spectra, with their intermissions, appear to take up + many seconds of time, and seem very variable in proportion to the + circumstances of fatigue or energy.</p> + + <p>4. It sometimes happens, if the eyeballs have been rubbed hard with + the fingers, that lucid sparks are seen in quick motion amidst the + spectrum we are attending to. This is similar to the flashes of fire from + a stroke on the eye in fighting, and is resembled by the warmth and glow, + which appears upon the skin after friction, and is probably owing to an + acceleration of the arterial blood into the vessels emptied by the + previous pressure. By being accustomed to observe such small sensations + in the eye, it is easy to see the circulation of the blood in this organ. + I have attended to this frequently, when I have observed my eyes more + than commonly sensible to other spectra. The circulation may be seen + either in both eyes at a time, or only in one of them; for as a certain + quantity of light is necessary to produce this curious phenomenon, if one + hand be brought nearer the closed eyelids than the other, the circulation + in that eye will for a time disappear. For the easier viewing the + circulation, it is sometimes necessary to rub the eyes with a certain + degree of force after they are closed, and to hold the breath rather + longer than is agreeable, which, by accumulating more blood in the eye, + facilitates the experiment; but in general it may be seen distinctly + after having examined other spectra with your back to the light, till the + eyes become weary; then having covered your closed eyelids for half a + minute, till the spectrum is faded away which you were examining, turn + your face to the light, and removing your hands from the eyelids, by and + by again shade them a little, and the circulation becomes curiously + distinct. The streams of blood are however generally seen to unite, which + shews it to be the venous circulation, owing, I suppose, to the greater + opacity of the colour of the blood in these vessels; for this venous + circulation is also much more easily seen by the microscope in the tail + of a tadpole.</p> + +<p class="center" style="margin-top: 2em;"><a name="sect_XL_10_5">5</a>. <i>Variation of spectra in respect to distinctness and size; with a new way +of magnifying objects.</i></p> + + <p>1. It was before observed, that when the two colours viewed together + were opposite to each other, as yellow and blue, red and green, &c. + according to the table of reflections and transmissions of light in Sir + Isaac Newton's Optics, B. II. Fig. 3. the spectra of those colours were + of all others the most brilliant, and best defined; because they were + combined of the reverse spectrum of one colour, and of the direct + spectrum of the other. Hence, in books printed with small types, or in + the minute graduation of thermometers, or of clock-faces, which are to be + seen at a distance, if the letters or figures are coloured with orange, + and the ground with indigo; or the letters with red, and the ground with + green; or any other lucid colour is used for the letters, the spectrum of + which is similar to the colour of the ground; such letters will be seen + much more distinctly, and with less confusion, than in black or white: + for as the spectrum of the letter is the same colour with the ground on + which they are seen, the unsteadiness of the eye in long attending to + them will not produce coloured lines by the edges of the letters, which + is the principal cause of their confusion. The beauty of colours lying in + vicinity to each other, whose spectra are thus reciprocally similar to + each colour, is owing to this greater ease that the eye experiences in + beholding them distinctly; and it is probable, in the organ of hearing, a + similar circumstance may constitute the pleasure of melody. Sir Isaac + Newton observes, that gold and indigo were agreeable when viewed + together; and thinks there may be some analogy between the sensations of + light and sound. (Optics, Qu. 14.)</p> + + <p>In viewing the spectra of bright objects, as of an area of red silk of + half an inch diameter on white paper, it is easy to magnify it to tenfold + its size: for if, when the spectrum is formed, you still keep your eye + fixed on the silk area, and remove it a few inches further from you, a + green circle is seen round the red silk: for the angle now subtended by + the silk is less than it was when the spectrum was formed, but that of + the spectrum continues the same, and our imagination places them at the + same distance. Thus when you view a spectrum on a sheet of white paper, + if you approach the paper to the eye, you may diminish it to a point; and + if the paper is made to recede from the eye, the spectrum will appear + magnified in proportion to the distance.</p> + + <div class="figright" style="width:25%;"> + <a href="images/fig5.png"><img width="100%" src="images/fig5.png" + alt="Fig. 5." /></a> + Fig. 5. + </div> + <p>I was surprised, and agreeably amused, with the following experiment. + I covered a paper about four inches square with yellow, and with a pen + filled with a blue colour wrote upon the middle of it the word BANKS in + capitals, as in Fig. 5, and sitting with my back to the sun, fixed my + eyes for a minute exactly on the center of the letter N in the middle of + the word; after closing my eyes, and shading them somewhat with my hand, + the word was distinctly seen in the spectrum in yellow letters on a blue + field; and then, on opening my eyes on a yellowish wall at twenty feet + distance, the magnified name of BANKS appeared written on the wall in + golden characters.</p> + +<p class="center" style="margin-top: 2em;"><i>Conclusion.</i></p> + + <p>It was observed by the learned M. Sauvage (Nosol. Method. Cl. VIII. + Ord. i.) that the pulsations of the optic artery might be perceived by + looking attentively on a white wall well illuminated. A kind of net-work, + darker than the other parts of the wall, appears and vanishes alternately + with every pulsation. This change of the colour of the wall he well + ascribes to the compression of the retina by the diastole of the artery. + The various colours produced in the eye by the pressure of the finger, or + by a stroke on it, as mentioned by Sir Isaac Newton, seem likewise to + originate from the unequal pressure on various parts of the retina. Now + as Sir Isaac Newton has shewn, that all the different colours are + reflected or transmitted by the laminæ of soap bubbles, or of air, + according to their different thickness or thinness, is it not probable, + that the effect of the activity of the retina may be to alter its + thickness or thinness, so as better to adapt it to reflect or transmit + the colours which stimulate it into action? May not muscular fibres exist + in the retina for this purpose, which may be less minute than the + locomotive muscles of microscopic animals? May not these muscular actions + of the retina constitute the sensation of light and colours; and the + voluntary repetitions of them, when the object is withdrawn, constitute + our memory of them? And lastly, may not the laws of the sensations of + light, here investigated, be applicable to all our other senses, and much + contribute to elucidate many phenomena of animal bodies both in their + healthy and diseased state; and thus render this investigation well + worthy the attention of the physician, the metaphysician, and the natural + philosopher?</p> + + <p>November 1, 1785.</p> + + <br clear="all" /> +<hr /> + + <div class="contents"> + <div class="stanza"> + <p>Dum, Liber! astra petis volitans trepidantibus alis,</p> + <p class="i2">Irruis immemori, parvula gutta, mari.</p> + <p>Me quoque, me currente rotâ revolubilis ætas</p> + <p class="i2">Volverit in tenebras,—i, Liber, ipse sequor.</p> + </div> + </div> + <br clear="all" /> +<hr /> + +<h3>INDEX TO THE SECTIONS OF PART FIRST.</h3> + + <div class="poem"> + <div class="stanza"> + </div> + + <div class="stanza"> + <p class="i16"><b>A.</b></p> + </div> + + <div class="stanza"> + <p>Abortion from fear, <a href="#sect_XXXIX_6_5">xxxix. 6. 5</a>.</p> + <p>Absorbent vessels, <a href="#sect_XXIII_3">xxiii. 3</a>. <a href="#sect_XXIX_1">xxix. 1</a>.</p> + <p>—— regurgitate their fluids, <a href="#sect_XXIX_2">xxix. 2</a>.</p> + <p>—— their valves, <a href="#sect_XXIX_2">xxix. 2</a>.</p> + <p>—— communicate with vena portarum, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>Absorption of solids, <a href="#sect_XXXIII_3_1">xxxiii. 3. 1</a>. <a href="#sect_XXXVII">xxxvii</a>.</p> + <p>—— of fluids in anasarca, <a href="#sect_XXXV_1_3">xxxv. 1. 3</a>.</p> + <p>Accumulation of sensorial power, <a href="#sect_IV_2">iv. 2</a>. <a href="#sect_XII_5_2">xii. 5. 2</a>.</p> + <p>Activity of system too great, cure of, <a href="#sect_XII_6">xii. 6</a>.</p> + <p>—— too small, cure of, <a href="#sect_XII_7">xii. 7</a>.</p> + <p>Age, old, <a href="#sect_XII_3_1">xii. 3. 1</a>. <a href="#sect_XXXVII_4">xxxvii. 4</a>.</p> + <p>Ague-fit, <a href="#sect_XII_7_1">xii. 7. 1</a>. <a href="#sect_XXXII_3_4">xxxii. 3. 4</a>. <a href="#sect_XXXII_9">xxxii. 9</a>.</p> + <p>—— how cured by bark, <a href="#sect_XII_3_4">xii. 3. 4</a>.</p> + <p>—— periods, how occasioned, <a href="#sect_XII_2_3">xii. 2. 3</a>. <a href="#sect_XXXII_3_4">xxxii. 3. 4</a>.</p> + <p>Ague cakes, <a href="#sect_XXXII_7">xxxii. 7</a>. <a href="#sect_XXXII_9">xxxii. 9</a>.</p> + <p>Air, sense of fresh, <a href="#sect_XIV_8">xiv. 8</a>.</p> + <p>—— injures ulcers, <a href="#sect_XXVIII_2">xxviii. 2</a>.</p> + <p>—— injected into veins, <a href="#sect_XXXII_5">xxxii. 5</a>.</p> + <p>Alcohol deleterious, <a href="#sect_XXX_3">xxx. 3</a>.</p> + <p>Alliterations, why agreeable, <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>Aloes in lessened doses, <a href="#sect_XII_3_1">xii. 3. 1</a>.</p> + <p>American natives indolent, <a href="#sect_XXXI_2">xxxi. 2</a>.</p> + <p>—— narrow shouldered, <a href="#sect_XXXI_1">xxxi. 1</a>.</p> + <p>Analogy intuitive, <a href="#sect_XVII_3_7">xvii. 3. 7</a>.</p> + <p>Animals less liable to madness, <a href="#sect_XXXIII_1">xxxiii. 1</a>.</p> + <p>—— less liable to contagion, <a href="#sect_XXXIII_1">xxxiii. 1</a>.</p> + <p>—— how to teach, <a href="#sect_XXII_3_2">xxii. 3. 2</a>.</p> + <p>—— their similarity to each other, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + <p>—— their changes after nativity, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + <p>—— their changes before nativity, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + <p>—— less liable to contagious diseases, why, <a href="#sect_XXXIII_1_5">xxxiii. 1. 5</a>.</p> + <p>—— less liable to delirium and insanity, why, <a href="#sect_XXXIII_1_5">xxxiii. 1. 5</a>.</p> + <p>—— easier to preserve than to reproduce, <a href="#sect_XXXVII">xxxvii</a>.</p> + <p>—— food, distaste of, <a href="#sect_XXVIII_1">xxviii. 1</a>.</p> + <p>—— appetency, <a href="#sect_XXXIX_4_7">xxxix. 4. 7</a>.</p> + <p>Antipathy, <a href="#sect_X_2_2">x. 2. 2</a>.</p> + <p>Aphthæ, <a href="#sect_XXVIII">xxviii</a>.</p> + <p>Apoplexy, <a href="#sect_XXXIV_1_7">xxxiv. 1. 7</a>.</p> + <p>—— not from deficient irritation, <a href="#sect_XXXII_2_1">xxxii. 2. 1</a>.</p> + <p>Appetites, <a href="#sect_XI_2_2">xi. 2. 2</a>. <a href="#sect_XIV_8">xiv. 8</a>.</p> + <p>Architecture, <a href="#sect_XXII_2">xxii. 2</a>. <a href="#sect_XVI_10">xvi. 10</a>.</p> + <p>Arts, fine, <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>Asparagus, its smell in urine, <a href="#sect_XXIX">xxix</a>.</p> + <p>Association defined, <a href="#sect_II_2_11">ii. 2. 11</a>. <a href="#sect_IV_7">iv. 7</a>. <a href="#sect_V_2">v. 2</a>.</p> + <p>—— associate motions, <a href="#sect_X">x</a>.</p> + <p>—— stronger than irritative ones, <a href="#sect_XXIV_2_8">xxiv. 2. 8</a>.</p> + <p>—— formed before nativity, <a href="#sect_XI_3">xi. 3</a>.</p> + <p>—— with irritative ones, <a href="#sect_XXIV_2_8">xxiv. 2. 8</a>.</p> + <p>—— with retrograde ones, <a href="#sect_XXV_7">xxv. 7</a>. <a href="#sect_XXV_10">xxv. 10</a>. <a href="#sect_XXV_15">xxv. 15</a>.</p> + <p>—— diseases from, <a href="#sect_XXXV">xxxv</a>.</p> + <p>Asthma, <a href="#sect_XVIII_15">xviii. 15</a>.</p> + <p>Attention, language of, <a href="#sect_XVI_8_6">xvi. 8. 6</a>.</p> + <p>Atrophy, <a href="#sect_XXVIII">xxviii</a>.</p> + <p>Aversion, origin of, <a href="#sect_XI_2_3">xi. 2. 3</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>B.</b></p> + </div> + + <div class="stanza"> + <p>Balance ourselves by vision, <a href="#sect_XX_1">xx. 1</a>.</p> + <p>Bandage increases absorption, <a href="#sect_XXXIII_3_2">xxxiii. 3. 2</a>.</p> + <p>Barrenness, <a href="#sect_XXXVI_2_3">xxxvi. 2. 3</a>.</p> + <p>Battement of sounds, <a href="#sect_XX_7">xx. 7</a>.</p> + <p>Bath, cold. See Cold Bath.</p> + <p>Beauty, sense of, <a href="#sect_XVI_6">xvi. 6</a>. <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>Bile-ducts, <a href="#sect_XXX">xxx</a>.</p> + <p>—— stones, <a href="#sect_XXX_1_3">xxx. 1. 3</a>.</p> + <p>—— regurgitates into the blood, <a href="#sect_XXIV_2_7">xxiv. 2. 7</a>.</p> + <p>—— vomiting of, <a href="#sect_XXX_1_3">xxx. 1. 3</a>.</p> + <p>Birds of passage, <a href="#sect_XVI_12">xvi. 12</a>.</p> + <p>—— nests of, <a href="#sect_XVI_13">xvi. 13</a>.</p> + <p>—— colour of their eggs, <a href="#sect_XXXIX_5">xxxix. 5</a>.</p> + <p>Biting in pain, <a href="#sect_XXXIV_1_3">xxxiv. 1. 3</a>.</p> + <p>—— of mad animals, <a href="#sect_XXXIV_1_3">xxxiv. 1. 3</a>.</p> + <p>Black spots on dice appear red, <a href="#sect_XL_3">xl. 3</a>.</p> + <p>Bladder, communication of with the intestines, <a href="#sect_XXIX_3">xxix. 3</a>.</p> + <p>—— of fish, <a href="#sect_XXIV_1_4">xxiv. 1. 4</a>.</p> + <p>Blood, transfusion of in nervous fevers, <a href="#sect_XXXII_4">xxxii. 4</a>.</p> + <p>—— deficiency of, <a href="#sect_XXXII_2">xxxii. 2</a>. and <a href="#sect_XXXII_4">4</a>.</p> + <p>—— from the vena portarum into the intestines, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>—— its momentum, <a href="#sect_XXXII_5_2">xxxii. 5. 2</a>.</p> + <p>—— momentum increased by venesection, <a href="#sect_XXXII_5_4">xxxii. 5. 4</a>.</p> + <p>—— drawn in nervous pains, <a href="#sect_XXXII_5_4">xxxii. 5. 4</a>.</p> + <p>—— its oxygenation, <a href="#sect_XXXVIII">xxxviii</a>.</p> + <p>Breasts of men, <a href="#sect_XIV_8">xiv. 8</a>.</p> + <p>Breathing, how learnt, <a href="#sect_XVI_4">xvi. 4</a>.</p> + <p>Brutes differ from men, <a href="#sect_XI_2_3">xi. 2. 3</a>. <a href="#sect_XVI_17">xvi. 17</a>.</p> + <p>Brutes. See Animals.</p> + <p>Buxton bath, why it feels warm, <a href="#sect_XII_2_1">xii. 2. 1</a>. <a href="#sect_XXXII_3_3">xxxii. 3. 3</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>C.</b></p> + </div> + + <div class="stanza"> + <p>Capillary vessels are glands, <a href="#sect_XXVI_1">xxvi. 1</a>.</p> + <p>Catalepsy, <a href="#sect_XXXIV_1_5">xxxiv. 1. 5</a>.</p> + <p>Catarrh from cold skin, <a href="#sect_XXXV_1_3">xxxv. 1. 3</a>. <a href="#sect_XXXV_2_3">xxxv. 2. 3</a>.</p> + <p>—— from thin caps in sleep, <a href="#sect_XVIII_15">xviii. 15</a>.</p> + <p>Catenation of motions defined, <a href="#sect_II_2_11">ii. 2. 11</a>. <a href="#sect_IV_7">iv. 7</a>.</p> + <p>—— cause of them, <a href="#sect_XVII_1_3">xvii. 1. 3</a>.</p> + <p>—— described, <a href="#sect_XVII">xvii</a>.</p> + <p>—— continue some time after their production, <a href="#sect_XVII_1_3">xvii. 1. 3</a>.</p> + <p>—— voluntary ones dissevered in sleep, <a href="#sect_XVII_1_12">xvii. 1. 12</a>. <a href="#sect_XVII_3_7">xvii. 3. 7</a>.</p> + <p>Cathartics, external, their operation, <a href="#sect_XXIX_7_6">xxix. 7. 6</a>.</p> + <p>Causation, animal, defined, <a href="#sect_II_2_11">ii. 2. 11</a>. <a href="#sect_IV_7">iv. 7</a>.</p> + <p>Cause of causes, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + <p>Causes inert and efficient, <a href="#sect_XXXIX_8_2">xxxix. 8. 2</a>.</p> + <p>—— active and passive, <a href="#sect_XXXIX_8_3">xxxix. 8. 3</a>.</p> + <p>—— proximate and remote, <a href="#sect_XXXIX_8_4">xxxix. 8. 4</a>.</p> + <p>Chick in the egg, oxygenation of, <a href="#sect_XXXVIII_2">xxxviii. 2</a>.</p> + <p>Child riding on a stick, <a href="#sect_XXXIV_2_6">xxxiv. 2. 6</a>.</p> + <p>Chilness after meals, <a href="#sect_XXI_3">xxi. 3</a>. <a href="#sect_XXXV_1_1">xxxv. 1. 1</a>.</p> + <p>Cholera, case of, <a href="#sect_XXV_13">xxv. 13</a>.</p> + <p>Circulation in the eye visible, <a href="#sect_XL_10_4">xl. 10. 4</a>.</p> + <p>Cold in the head, <a href="#sect_XII_6_5">xii. 6. 5</a>.</p> + <p>—— perceived by the teeth, <a href="#sect_XXXII_3_1">xxxii. 3. 1</a>. <a href="#sect_XIV_6">xiv. 6</a>.</p> + <p>—— air, uses of in fevers, <a href="#sect_XXXII_3_3">xxxii. 3. 3</a>.</p> + <p>—— feet, produces coryza, <a href="#sect_XXXV_2_3">xxxv. 2. 3</a>. <a href="#sect_XXXV_1_3">xxxv. 1. 3</a>.</p> + <p>—— bath, why it strengthens, <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + <p>—— short and cold breathing in it, <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + <p>—— produces a fever-fit, <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + <p>—— fit of fever the consequence of hot fit, <a href="#sect_XXXII_9_3">xxxii. 9. 3</a>.</p> + <p>—— bathing in pulmonary hæmorrhage, <a href="#sect_XXVII_1">xxvii. 1</a>.</p> + <p>—— fits of fever, <a href="#sect_XXXII_4">xxxii. 4</a>. <a href="#sect_XXXII_9">xxxii. 9</a>. <a href="#sect_XVII_3_3">xvii. 3. 3</a>.</p> + <p>Colours of animals, efficient cause of, <a href="#sect_XXXIX_5_1">xxxix. 5. 1</a>.</p> + <p>—— of eggs from female imagination, <a href="#sect_XXXIX_5_1">xxxix. 5. 1</a>.</p> + <p>—— of the choroid coat of the eye, <a href="#sect_XXXIX_5_1">xxxix. 5. 1</a>.</p> + <p>—— of birds nests, <a href="#sect_XVI_13">xvi. 13</a>.</p> + <p>Comparing ideas, <a href="#sect_XV_3">xv. 3</a>.</p> + <p>Consciousness, <a href="#sect_XV_3_4">xv. 3. 4</a>.</p> + <p>—— in dreams, <a href="#sect_XVIII_13">xviii. 13</a>.</p> + <p>Consent of parts. See Sympathy.</p> + <p>Consumption, its temperament, <a href="#sect_XXXI_1">xxxi. 1</a>. and <a href="#sect_XXXI_2">2</a>.</p> + <p>—— of dark-eyed patients, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>—— of light-eyed patients, <a href="#sect_XXVIII_2">xxviii. 2</a>.</p> + <p>—— is contagious, <a href="#sect_XXXIII_2_7">xxxiii. 2. 7</a>.</p> + <p>Contagion, <a href="#sect_XII_3_6">xii. 3. 6</a>. <a href="#sect_XIX_9">xix. 9</a>. <a href="#sect_XXXIII_2_6">xxxiii. 2. 6</a>. and <a href="#sect_XXXIII_2_8">8</a>. <a href="#sect_XXII_3_3">xxii. 3. 3</a>.</p> + <p>—— does not enter the blood, <a href="#sect_XXXIII_2_10">xxxiii. 2. 10</a>. <a href="#sect_XXII_3_3">xxii. 3. 3</a>.</p> + <p>Contraction and attraction, <a href="#sect_IV_1">iv. 1</a>.</p> + <p>—— of fibres produces sensation, <a href="#sect_IV_5">iv. 5</a>. <a href="#sect_XII_1_6">xii. 1. 6</a>.</p> + <p>—— continues some time, <a href="#sect_XII_1_5">xii. 1. 5</a>.</p> + <p>—— alternates with relaxation, <a href="#sect_XII_1_3">xii. 1. 3</a>.</p> + <p>Convulsion, <a href="#sect_XVII_1_8">xvii. 1. 8</a>. <a href="#sect_XXXIV_1_1">xxxiv. 1. 1</a>. and <a href="#sect_XXXIV_1_4">4</a>. <a href="#sect_III_5_8">iii. 5. 8</a>.</p> + <p>—— of particular muscles, <a href="#sect_XVII_1_8">xvii. 1. 8</a>.</p> + <p>—— periods of, <a href="#sect_XXXVI_3_9">xxxvi. 3. 9</a>.</p> + <p>Coryza. See Catarrh.</p> + <p>Cough, nervous, periods of, <a href="#sect_XXXVI_3_9">xxxvi. 3. 9</a>.</p> + <p>Cramp, <a href="#sect_XVIII_15">xviii. 15</a>. <a href="#sect_XXXIV_1_7">xxxiv. 1. 7</a>.</p> + <p>Critical days from lunations, <a href="#sect_XXXVI_4">xxxvi. 4</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>D.</b></p> + </div> + + <div class="stanza"> + <p>Darkish room, why we see well in it, <a href="#sect_XII_2_1">xii. 2. 1</a>.</p> + <p>Debility sensorial and stimulatory, <a href="#sect_XII_2_1">xii. 2. 1</a>.</p> + <p>—— direct and indirect of Dr. Brown, <a href="#sect_XII_2_1">xii. 2. 1</a>. <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + <p>—— See Weakness.</p> + <p>—— from drinking spirits, cure of, <a href="#sect_XII_7_8">xii. 7. 8</a>.</p> + <p>—— in fevers, cure of, <a href="#sect_XII_7_8">xii. 7. 8</a>.</p> + <p>Deliberation, what, <a href="#sect_XXXIV_1">xxxiv. 1</a>.</p> + <p>Delirium, two kinds of, <a href="#sect_XXXIII_1_4">xxxiii. 1. 4</a>. <a href="#sect_XXXIV_2_2">xxxiv. 2. 2</a>.</p> + <p>—— cases of, <a href="#sect_III_5_8">iii. 5. 8</a>.</p> + <p>—— prevented by dreams, <a href="#sect_XVIII_2">xviii. 2</a>.</p> + <p>Desire, origin of, <a href="#sect_XI_2_3">xi. 2. 3</a>.</p> + <p>Diabetes explained, <a href="#sect_XXIX_4">xxix. 4</a>.</p> + <p>—— with bloody urine, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>—— in the night, <a href="#sect_XVIII_15">xviii. 15</a>.</p> + <p>Diarrhœa, <a href="#sect_XXIX_4">xxix. 4</a>.</p> + <p>Digestion, <a href="#sect_XXXIII_1">xxxiii. 1</a>. <a href="#sect_XXXVII">xxxvii</a>.</p> + <p>—— strengthened by emetics, <a href="#sect_XXXV_1_3">xxxv. 1. 3</a>.</p> + <p>—— strengthened by regular hours, why, <a href="#sect_XXXVI_2_1">xxxvi. 2. 1</a>.</p> + <p>Digitalis, use of in dropsy, <a href="#sect_XXIX_5_2">xxix. 5. 2</a>.</p> + <p>Distention acts as a stimulus, <a href="#sect_XXXII_4">xxxii. 4</a>.</p> + <p>—— See Extension.</p> + <p>Distinguishing, <a href="#sect_XV_3">xv. 3</a>.</p> + <p>Diurnal circle of actions, <a href="#sect_XXV_4">xxv. 4</a>.</p> + <p>Doubting, <a href="#sect_XV_3">xv. 3</a>.</p> + <p>Dreams, <a href="#sect_VIII_1_2">viii. 1. 2</a>. <a href="#sect_XIV_2_5">xiv. 2. 5</a>.</p> + <p>—— their inconsistency, <a href="#sect_XVIII_17">xviii. 17</a>.</p> + <p>—— no surprise in them, <a href="#sect_XVIII_17">xviii. 17</a>.</p> + <p>—— much novelty of combination, <a href="#sect_XVIII_9">xviii. 9</a>.</p> + <p>Dropsies explained, <a href="#sect_XXIX_5_1">xxix. 5. 1</a>.</p> + <p>Dropsy cured by insanity, <a href="#sect_XXXIV_2_7">xxxiv. 2. 7</a>.</p> + <p>—— cure of, <a href="#sect_XXIX_5_2">xxix. 5. 2</a>.</p> + <p>Drunkards weak till next day, <a href="#sect_XVII_1_7">xvii. 1. 7</a>.</p> + <p>—— stammer, and stagger, and weep, <a href="#sect_XII_4_1">xii. 4. 1</a>. <a href="#sect_XXI_4">xxi. 4</a>.</p> + <p>—— see objects double, why, <a href="#sect_XXI_7">xxi. 7</a>.</p> + <p>—— become delirious, sleepy, stupid, <a href="#sect_XXI_5">xxi. 5</a>.</p> + <p>Drunkenness. See Intoxication, <a href="#sect_XXI">xxi</a>.</p> + <p>—— diminished by attention, <a href="#sect_XXI_8">xxi. 8</a>.</p> + <p>Dyspnœa in cold bath, <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>E.</b></p> + </div> + + <div class="stanza"> + <p>Ear, a good one, <a href="#sect_XVI_10">xvi. 10</a>.</p> + <p>—— noise in, <a href="#sect_XX_7">xx. 7</a>.</p> + <p>Eggs of frogs, fish, fowl, <a href="#sect_XXXIX_2">xxxix. 2</a>.</p> + <p>—— of birds, why spotted, <a href="#sect_XXXIX_5">xxxix. 5</a>.</p> + <p>—— with double yolk, <a href="#sect_XXXIX_4_4">xxxix. 4. 4</a>.</p> + <p>Electricity, <a href="#sect_XII_1">xii. 1</a>. <a href="#sect_XIV_9">xiv. 9</a>.</p> + <p>—— jaundice cured by it, <a href="#sect_XXX_1_2">xxx. 1. 2</a>.</p> + <p>Embryon produced by the male, <a href="#sect_XXXIX_2">xxxix. 2</a>.</p> + <p>—— consists of a living fibre, <a href="#sect_XXXIX_4">xxxix. 4</a>.</p> + <p>—— absorbs nutriment, receives oxygen, <a href="#sect_XXXIX_1">xxxix. 1</a>.</p> + <p>—— its actions and sensations, <a href="#sect_XVI_2">xvi. 2</a>.</p> + <p>Emetic. See Vomiting.</p> + <p>Emotions, <a href="#sect_XI_2_2">xi. 2. 2</a>.</p> + <p>Ennui, or tædium vitæ, <a href="#sect_XXXIV_2_3">xxxiv. 2. 3</a>. <a href="#sect_XXXIII_1_1">xxxiii. 1. 1</a>. <a href="#sect_XXXIX_6">xxxix. 6</a>.</p> + <p>Epileptic fits explained, <a href="#sect_XXXIV_1_4">xxxiv. 1. 4</a>. <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>—— in sleep, why, <a href="#sect_XVIII_14">xviii. 14</a>. & <a href="#sect_XVIII_15">15</a>.</p> + <p>Equinoxial lunations, <a href="#sect_XXXII_6">xxxii. 6</a>.</p> + <p>Excitability perpetually varies, <a href="#sect_XII_1_7">xii. 1. 7</a>.</p> + <p>—— synonymous to quantity of sensorial power, <a href="#sect_XII_1_7">xii. 1. 7</a>.</p> + <p>Exercise, its use, <a href="#sect_XXXII_5_3">xxxii. 5. 3</a>.</p> + <p>Exertion of sensorial power defined, <a href="#sect_XII_2_1">xii. 2. 1</a>.</p> + <p>Existence in space, <a href="#sect_XIV_2_5">xiv. 2. 5</a>.</p> + <p>Extension, sense of, <a href="#sect_XIV_7">xiv. 7</a>.</p> + <p>Eyes become black in some epilepsies, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>F.</b></p> + </div> + + <div class="stanza"> + <p>Face, flushing of after dinner, <a href="#sect_XXXV_1_1">xxxv. 1. 1</a>.</p> + <p>—— why first affected in small-pox, <a href="#sect_XXXV_1_1">xxxv. 1. 1</a>.</p> + <p>—— red from inflamed liver, <a href="#sect_XXXV_2_2">xxxv. 2. 2</a>.</p> + <p>Fainting fits, <a href="#sect_XII_7_1">xii. 7. 1</a>. <a href="#sect_XIV_7">xiv. 7</a>.</p> + <p>Fear, language of, <a href="#sect_XVI_8_1">xvi. 8. 1</a>.</p> + <p>—— a cause of fever, <a href="#sect_XXXII_8">xxxii. 8</a>.</p> + <p>—— cause of, <a href="#sect_XVII_3_7">xvii. 3. 7</a>.</p> + <p>Fetus. See Embryon, <a href="#sect_XVI_2">xvi. 2</a>. <a href="#sect_XXXIX_1">xxxix. 1</a>.</p> + <p>Fevers, irritative, <a href="#sect_XXXII_1">xxxii. 1</a>.</p> + <p>—— intermittent, <a href="#sect_XXXII_1">xxxii. 1</a>. <a href="#sect_XXXII_3">xxxii. 3</a>.</p> + <p>—— sensitive, <a href="#sect_XXXIII_1">xxxiii. 1</a>.</p> + <p>—— not an effort of nature for relief, <a href="#sect_XXXII_10">xxxii. 10</a>.</p> + <p>—— paroxysms of, <a href="#sect_XII_7_1">xii. 7. 1</a>. <a href="#sect_XII_2_3">xii. 2. 3</a>. <a href="#sect_XII_3_5">xii. 3. 5</a>.</p> + <p>—— why some intermit and not others, <a href="#sect_XXXVI_1">xxxvi. 1</a>.</p> + <p>—— cold fits of, <a href="#sect_XXXII_4">xxxii. 4</a>. <a href="#sect_XXXII_9">xxxii. 9</a>. <a href="#sect_XVII_3_3">xvii. 3. 3</a>.</p> + <p>—— periods of, <a href="#sect_XXXVI_3">xxxvi. 3</a>.</p> + <p>—— have solar or lunar periods, <a href="#sect_XXXII_6">xxxii. 6</a>.</p> + <p>—— source of the symptoms of, <a href="#sect_XXXII_1">xxxii. 1</a>.</p> + <p>—— prostration of strength in, <a href="#sect_XII_4_1">xii. 4. 1</a>. <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + <p>—— cure of, <a href="#sect_XII_6_1">xii. 6. 1</a>.</p> + <p>—— how cured by the bark, <a href="#sect_XII_3_4">xii. 3. 4</a>.</p> + <p>—— cured by increased volition, <a href="#sect_XII_2_4">xii. 2. 4</a>. <a href="#sect_XXXIV_2_8">xxxiv. 2. 8</a>.</p> + <p>—— best quantity of stimulus in, <a href="#sect_XII_7_8">xii. 7. 8</a>.</p> + <p>Fibres. See Muscles.</p> + <p>Fibres, their mobility, <a href="#sect_XII_1_7">xii. 1. 7</a>. <a href="#sect_XII_1_1">xii. 1. 1</a>.</p> + <p>—— contractions of, <a href="#sect_VI">vi</a>. <a href="#sect_XII_1_1">xii. 1. 1</a>.</p> + <p>—— four classes of their motions, <a href="#sect_VI">vi</a>.</p> + <p>—— their motions distinguished from sensorial ones, <a href="#sect_V_3">v. 3</a>.</p> + <p>Figure, <a href="#sect_XIV_2_2">xiv. 2. 2</a>. <a href="#sect_III_1">iii. 1</a>.</p> + <p>Fish, their knowledge, <a href="#sect_XVI_14">xvi. 14</a>.</p> + <p>Foxglove, its use in dropsies, <a href="#sect_XXIX_5_2">xxix. 5. 2</a>.</p> + <p>—— overdose of, <a href="#sect_XXV_17">xxv. 17</a>.</p> + <p>Free-will, <a href="#sect_XV_3_7">xv. 3. 7</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>G.</b></p> + </div> + + <div class="stanza"> + <p>Gall-stone, <a href="#sect_XXV_17">xxv. 17</a>.</p> + <p>—— See Bile-stones.</p> + <p>Generation, <a href="#sect_XXXIII_1">xxxiii. 1</a>. <a href="#sect_XXXIX">xxxix</a>.</p> + <p>Gills of fish, <a href="#sect_XXXVIII_2">xxxviii. 2</a>.</p> + <p>Glands, <a href="#sect_XXIII_2">xxiii. 2</a>.</p> + <p>—— conglobate glands, <a href="#sect_XXIII_3">xxiii. 3</a>.</p> + <p>—— have their peculiar stimulus, <a href="#sect_XI_1">xi. 1</a>.</p> + <p>—— their senses, <a href="#sect_XIV_9">xiv. 9</a>. <a href="#sect_XXXIX_6">xxxix. 6</a>.</p> + <p>—— invert their motions, <a href="#sect_XXV_7">xxv. 7</a>.</p> + <p>—— increase their motions, <a href="#sect_XXV_7">xxv. 7</a>.</p> + <p>Golden rule for exhibiting wine, <a href="#sect_XII_7_8">xii. 7. 8</a>.</p> + <p>—— for leaving off wine, <a href="#sect_XII_7_8">xii. 7. 8</a>.</p> + <p>Gout from inflamed liver, <a href="#sect_XXXV_2_2">xxxv. 2. 2</a>. <a href="#sect_XVIII_16">xviii. 16</a>. <a href="#sect_XXIV_2_8">xxiv. 2. 8</a>.</p> + <p>—— in the stomach, <a href="#sect_XXIV_2_8">xxiv. 2. 8</a>. <a href="#sect_XXV_17">xxv. 17</a>.</p> + <p>—— why it returns after evacuations, <a href="#sect_XXXII_4">xxxii. 4</a>.</p> + <p>—— owing to vinous spirit only, <a href="#sect_XXI_10">xxi. 10</a>.</p> + <p>—— periods of, <a href="#sect_XXXVI_3_6">xxxvi. 3. 6</a>.</p> + <p>Grinning in pain, <a href="#sect_XXXIV_1_3">xxxiv. 1. 3</a>.</p> + <p>Gyration on one foot, <a href="#sect_XX_5">xx. 5</a>. and <a href="#sect_XX_6">6</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>H.</b></p> + </div> + + <div class="stanza"> + <p>Habit defined, <a href="#sect_II_2_11">ii. 2. 11</a>. <a href="#sect_IV_7">iv. 7</a>.</p> + <p>Hæmorrhages, periods of, <a href="#sect_XXXVI_3_11">xxxvi. 3. 11</a>.</p> + <p>—— from paralysis of veins, <a href="#sect_XXVII_1">xxvii. 1</a>. and <a href="#sect_XXVII_2">2</a>.</p> + <p>Hair and nails, <a href="#sect_XXXIX_3_2">xxxix. 3. 2</a>.</p> + <p>—— colour of, <a href="#sect_XXXIX_5_1">xxxix. 5. 1</a>.</p> + <p>Harmony, <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>Head-achs, <a href="#sect_XXXV_2_1">xxxv. 2. 1</a>.</p> + <p>Hearing, <a href="#sect_XIV_4">xiv. 4</a>.</p> + <p>Heat, sense of, <a href="#sect_XIV_6">xiv. 6</a>. <a href="#sect_XXXII_3_1">xxxii. 3. 1</a>.</p> + <p>—— produced by the glands, <a href="#sect_XXXII_3">xxxii. 3</a>.</p> + <p>—— external and internal, <a href="#sect_XXXII_3_1">xxxii. 3. 1</a>.</p> + <p>—— atmosphere of heat, <a href="#sect_XXXII_3_1">xxxii. 3. 1</a>.</p> + <p>—— increases during sleep, <a href="#sect_XVIII_15">xviii. 15</a>.</p> + <p>Hemicrania, <a href="#sect_XXXV_2_1">xxxv. 2. 1</a>.</p> + <p>—— from decaying teeth, <a href="#sect_XXXV_2_1">xxxv. 2. 1</a>.</p> + <p>Hepatitis, cause of, <a href="#sect_XXXV_2_3">xxxv. 2. 3</a>.</p> + <p>Hereditary diseases, <a href="#sect_XXXIX_7_6">xxxix. 7. 6</a>.</p> + <p>Hermaphrodite insects, <a href="#sect_XXXIX_5">xxxix. 5</a>.</p> + <p>Herpes, <a href="#sect_XXVIII_2">xxviii. 2</a>.</p> + <p>—— from inflamed kidney, <a href="#sect_XXXV_2_2">xxxv. 2. 2</a>.</p> + <p>Hilarity from diurnal fever, <a href="#sect_XXXVI_3_1">xxxvi. 3. 1</a>.</p> + <p>Hunger, sense of, <a href="#sect_XIV_8">xiv. 8</a>.</p> + <p>Hydrophobia, <a href="#sect_XXII_3_3">xxii. 3. 3</a>.</p> + <p>Hypochondriacism, <a href="#sect_XXXIII_1_1">xxxiii. 1. 1</a>. <a href="#sect_XXXIV_2_3">xxxiv. 2. 3</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>I.</b></p> + </div> + + <div class="stanza"> + <p>Ideas defined, <a href="#sect_II_2_7">ii. 2. 7</a>.</p> + <p>—— are motions of the organs of sense, <a href="#sect_III_4">iii. 4</a>. <a href="#sect_XVIII_5">xviii. 5</a>. <a href="#sect_XVIII_10">xviii. 10</a>. <a href="#sect_XVIII_6">xviii. 6</a>.</p> + <p>—— analogous to muscular motions, <a href="#sect_III_5">iii. 5</a>.</p> + <p>—— continue some time, <a href="#sect_XX_6">xx. 6</a>.</p> + <p>—— new ones cannot be invented, <a href="#sect_III_6_1">iii. 6. 1</a>.</p> + <p>—— abstracted ones, <a href="#sect_III_6_4">iii. 6. 4</a>.</p> + <p>—— inconsistent trains of, <a href="#sect_XVIII_17">xviii. 17</a>.</p> + <p>—— perish with the organ of sense, <a href="#sect_III_4_4">iii. 4. 4</a>.</p> + <p>—— painful from inflammation of the organ, <a href="#sect_III_5_5">iii. 5. 5</a>.</p> + <p>—— irritative ones, <a href="#sect_VII_1_4">vii. 1. 4</a>. <a href="#sect_VII_3_2">vii. 3. 2</a>. <a href="#sect_XV_2">xv. 2</a>. <a href="#sect_XX_7">xx. 7</a>.</p> + <p>—— of resemblance, contiguity, causation, <a href="#sect_VIII_3_2">viii. 3. 2</a>. <a href="#sect_X_3_3">x. 3. 3</a>.</p> + <p>—— resemble the figure and other properties of bodies, <a href="#sect_XIV_2_2">xiv. 2. 2</a>.</p> + <p>—— received in tribes, <a href="#sect_XV_1">xv. 1</a>.</p> + <p>—— of the same sense easier combined, <a href="#sect_XV_1_1">xv. 1. 1</a>.</p> + <p>—— of reflection, <a href="#sect_XV_1_6">xv. 1. 6</a>. <a href="#sect_II_2_12">ii. 2. 12</a>.</p> + <p>Ideal presence, <a href="#sect_XV_1_7">xv. 1. 7</a>.</p> + <p>Identity, <a href="#sect_XV_3_5">xv. 3. 5</a>. <a href="#sect_XVIII_13">xviii. 13</a>.</p> + <p>Iliac passion, <a href="#sect_XXV_15">xxv. 15</a>.</p> + <p>Imagination, <a href="#sect_VIII_1_2">viii. 1. 2</a>. <a href="#sect_XV_1_7">xv. 1. 7</a>. <a href="#sect_XV_2_2">xv. 2. 2</a>.</p> + <p>—— of the male forms the sex, <a href="#sect_XXXIX_6">xxxix. 6</a>.</p> + <p>Imitation, origin of, <a href="#sect_XII_3_3">xii. 3. 3</a>. <a href="#sect_XXXIX_5">xxxix. 5</a>. <a href="#sect_XXII_3">xxii. 3</a>. <a href="#sect_XVI_7">xvi. 7</a>.</p> + <p>Immaterial beings, <a href="#sect_XIV_1">xiv. 1</a>. <a href="#sect_XIV_2_4">xiv. 2. 4</a>.</p> + <p>Impediment of speech, <a href="#sect_XVII_1_10">xvii. 1. 10</a>. <a href="#sect_XVII_2_10">xvii. 2. 10</a>.</p> + <p>Infection. See Contagion.</p> + <p>Inflammation, <a href="#sect_XII_2_3">xii. 2. 3</a>. <a href="#sect_XXXIII_2_2">xxxiii. 2. 2</a>.</p> + <p>—— great vascular exertion in, <a href="#sect_XII_2_1">xii. 2. 1</a>.</p> + <p>—— not from pains from defect of stimulus, <a href="#sect_XXXIII_2_3">xxxiii. 2. 3</a>.</p> + <p>—— of parts previously insensible, <a href="#sect_XII_3_7">xii. 3. 7</a>.</p> + <p>—— often distant from its cause, <a href="#sect_XXIV_2_8">xxiv. 2. 8</a>.</p> + <p>—— observes solar days, <a href="#sect_XXXII_6">xxxii. 6</a>.</p> + <p>—— of the eye, <a href="#sect_XXXIII_3_1">xxxiii. 3. 1</a>.</p> + <p>—— of the bowels prevented by their continued action in sleep, <a href="#sect_XVIII_2">xviii. 2</a>.</p> + <p>Inoculation with blood, <a href="#sect_XXXIII_2_10">xxxiii. 2. 10</a>.</p> + <p>Insane people, their great strength, <a href="#sect_XII_2_1">xii. 2. 1</a>.</p> + <p>Insanity (see Madness) pleasurable one, <a href="#sect_XXXIV_2_6">xxxiv. 2. 6</a>.</p> + <p>Insects, their knowledge, <a href="#sect_XVI_15">xvi. 15</a>. and <a href="#sect_XVI_16">16</a>.</p> + <p>—— in the heads of calves, <a href="#sect_XXXIX_1">xxxix. 1</a>.</p> + <p>—— class of, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + <p>Instinctive actions defined, <a href="#sect_XVI_1">xvi. 1</a>.</p> + <p>Intestines, <a href="#sect_XXV_3">xxv. 3</a>.</p> + <p>Intoxication relieves pain, why, <a href="#sect_XXI_3">xxi. 3</a>.</p> + <p>—— from food after fatigue, <a href="#sect_XXI_2">xxi. 2</a>.</p> + <p>—— diseases from it, <a href="#sect_XXI_10">xxi. 10</a>.</p> + <p>—— See Drunkenness.</p> + <p>Intuitive analogy, <a href="#sect_XVII_3_7">xvii. 3. 7</a>.</p> + <p>Invention, <a href="#sect_XV_3_3">xv. 3. 3</a>.</p> + <p>Irritability increases during sleep, <a href="#sect_XVIII_15">xviii. 15</a>.</p> + <p>Itching, <a href="#sect_XIV_9">xiv. 9</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>J.</b></p> + </div> + + <div class="stanza"> + <p>Jaundice from paralysis of the liver, <a href="#sect_XXX_1_2">xxx. 1. 2</a>.</p> + <p>—— cured by electricity, <a href="#sect_XXX_1_2">xxx. 1. 2</a>.</p> + <p>Jaw-locked, <a href="#sect_XXXIV_1_5">xxxiv. 1. 5</a>.</p> + <p>Judgment, <a href="#sect_XV_3">xv. 3</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>K.</b></p> + </div> + + <div class="stanza"> + <p>Knowledge of various animals, <a href="#sect_XVI_11">xvi. 11</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>L.</b></p> + </div> + + <div class="stanza"> + <p>Lachrymal sack, <a href="#sect_XVI_8">xvi. 8</a>. <a href="#sect_XXIV_2_2">xxiv. 2. 2</a>. and <a href="#sect_XXIV_2_7">7</a>.</p> + <p>Lacteals, paralysis of, <a href="#sect_XXVIII">xxviii</a>.</p> + <p>—— See Absorbents.</p> + <p>Lady playing on the harpsichord, <a href="#sect_XVII_2">xvii. 2</a>.</p> + <p>—— distressed for her dying bird, <a href="#sect_XVII_2_10">xvii. 2. 10</a>.</p> + <p>Language, natural, its origin, <a href="#sect_XVI_7">xvi. 7</a>. & <a href="#sect_XVI_8">8</a>.</p> + <p>—— of various passions described, <a href="#sect_XVI_8">xvi. 8</a>.</p> + <p>—— artificial, of various animals, <a href="#sect_XVI_9">xvi. 9</a>.</p> + <p>—— theory of, <a href="#sect_XXXIX_8_3">xxxix. 8. 3</a>.</p> + <p>Lapping of puppies, <a href="#sect_XVI_4">xvi. 4</a>.</p> + <p>Laughter explained, <a href="#sect_XXXIV_1_4">xxxiv. 1. 4</a>.</p> + <p>—— from tickling, <a href="#sect_XVII_3_5">xvii. 3. 5</a>. <a href="#sect_XXXIV_1_4">xxxiv. 1. 4</a>.</p> + <p>—— from frivolous ideas, <a href="#sect_XXXIV_1_4">xxxiv. 1. 4</a>. <a href="#sect_XVIII_12">xviii. 12</a>.</p> + <p>Life, long, art of producing, <a href="#sect_XXXVII">xxxvii</a>.</p> + <p>Light has no momentum, <a href="#sect_III_3_1">iii. 3. 1</a>.</p> + <p>Liquor amnii, <a href="#sect_XVI_2">xvi. 2</a>. <a href="#sect_XXXVIII_2">xxxviii. 2</a>.</p> + <p>—— is nutritious, <a href="#sect_XXXVIII_3">xxxviii. 3</a>.</p> + <p>—— frozen, <a href="#sect_XXXVIII_3">xxxviii. 3</a>.</p> + <p>Liver, paralysis of, <a href="#sect_XXX_1_4">xxx. 1. 4</a>.</p> + <p>—— large of geese, <a href="#sect_XXX_1_6">xxx. 1. 6</a>.</p> + <p>Love, sentimental, its origin, <a href="#sect_XVI_6">xvi. 6</a>.</p> + <p>—— animal, <a href="#sect_XIV_8">xiv. 8</a>. <a href="#sect_XVI_5">xvi. 5</a>.</p> + <p>Lunar periods affect diseases, <a href="#sect_XXXII_6">xxxii. 6</a>.</p> + <p>Lust, <a href="#sect_XIV_8">xiv. 8</a>. <a href="#sect_XVI_5">xvi. 5</a>.</p> + <p>Lymphatics, paralysis of, <a href="#sect_XXVIII">xxviii</a>.</p> + <p>—— See Absorbents.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>M.</b></p> + </div> + + <div class="stanza"> + <p>Mad-dog, bite of, <a href="#sect_XXII_3_3">xxii. 3. 3</a>.</p> + <p>Madness, <a href="#sect_XXXIV_2_1">xxxiv. 2. 1</a>. <a href="#sect_XII_2_1">xii. 2. 1</a>.</p> + <p>Magnetism, <a href="#sect_XII_1_1">xii. 1. 1</a>.</p> + <p>Magnifying objects, new way of, <a href="#sect_XL_10_5">xl. 10. 5</a>.</p> + <p>Male animals have teats, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + <p>—— pigeons give milk, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + <p>Man distinguished from brutes, <a href="#sect_XI_2_3">xi. 2. 3</a>. <a href="#sect_XVI_17">xvi. 17</a>.</p> + <p>Material world, <a href="#sect_XIV_1">xiv. 1</a>. <a href="#sect_XIV_2_5">xiv. 2. 5</a>. <a href="#sect_XVIII_7">xviii. 7</a>.</p> + <p>Matter, penetrability of, <a href="#sect_XIV_2_3">xiv. 2. 3</a>.</p> + <p>—— purulent, <a href="#sect_XXXIII_2_4">xxxiii. 2. 4</a>.</p> + <p>Measles, <a href="#sect_XXXIII_2_9">xxxiii. 2. 9</a>.</p> + <p>Membranes, <a href="#sect_XXVI_2">xxvi. 2</a>.</p> + <p>Memory defined, <a href="#sect_II_2_10">ii. 2. 10</a>. <a href="#sect_XV_1_7">xv. 1. 7</a>. <a href="#sect_XV_3">xv. 3</a>.</p> + <p>Menstruation by lunar periods, <a href="#sect_XXXII_6">xxxii. 6</a>.</p> + <p>Miscarriage from fear, <a href="#sect_XXXIX_6_5">xxxix. 6. 5</a>.</p> + <p>Mobility of fibres, <a href="#sect_XII_1_7">xii. 1. 7</a>.</p> + <p>Momentum of the blood, <a href="#sect_XXXII_5_2">xxxii. 5. 2</a>.</p> + <p>—— sometimes increased by venesection, <a href="#sect_XXXII_5_4">xxxii. 5. 4</a>.</p> + <p>Monsters, <a href="#sect_XXXIX_4_4">xxxix. 4. 4</a>. and <a href="#sect_XXXIX_5_2">5. 2</a>.</p> + <p>—— without heads, <a href="#sect_XXXVIII_3">xxxviii. 3</a>.</p> + <p>Moon and sun, their influence, <a href="#sect_XXXII_6">xxxii. 6</a>.</p> + <p>Mortification, <a href="#sect_XXXIII_3_3">xxxiii. 3. 3</a>.</p> + <p>Motion is either cause or effect, <a href="#sect_I">i</a>. <a href="#sect_XIV_2_2">xiv. 2. 2</a>.</p> + <p>—— primary and secondary, <a href="#sect_I">i</a>.</p> + <p>—— animal, <a href="#sect_I">i</a>. <a href="#sect_III_1">iii. 1</a>.</p> + <p>—— propensity to, <a href="#sect_XXII_1">xxii. 1</a>.</p> + <p>—— animal, continue some time after their production, <a href="#sect_XVII_1_3">xvii. 1. 3</a>.</p> + <p>—— defined, a variation of figure, <a href="#sect_III_1">iii. 1</a>. <a href="#sect_XIV_2_2">xiv. 2. 2</a>. <a href="#sect_XXXIX_8">xxxix. 8</a>.</p> + <p>Mucus, experiments on, <a href="#sect_XXVI_1">xxvi. 1</a>.</p> + <p>—— secretion of, <a href="#sect_XXVI_2">xxvi. 2</a>.</p> + <p>Mules, <a href="#sect_XXXIX_4_5">xxxix. 4. 5</a>. and <a href="#sect_XXXIX_4_6">6</a>. <a href="#sect_XXXIX_5_2">xxxix. 5. 2</a>.</p> + <p>Mule plants, <a href="#sect_XXXIX_2">xxxix. 2</a>.</p> + <p>Muscæ volitantes, <a href="#sect_XL_2">xl. 2</a>.</p> + <p>Muscles constitute an organ of sense, <a href="#sect_XIV_7">xiv. 7</a>. <a href="#sect_II_2_4">ii. 2. 4</a>.</p> + <p>—— stimulated by extension, <a href="#sect_XI_1">xi. 1</a>. <a href="#sect_XIV_7">xiv. 7</a>.</p> + <p>—— contract by spirit of animation, <a href="#sect_XII_1_1">xii. 1. 1</a>. and <a href="#sect_XII_1_3">3</a>.</p> + <p>Music, <a href="#sect_XVI_10">xvi. 10</a>. <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>Musical time, why agreeable, <a href="#sect_XII_3_3">xii. 3. 3</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>N.</b></p> + </div> + + <div class="stanza"> + <p>Nausea, <a href="#sect_XXV_6">xxv. 6</a>.</p> + <p>Nerves and brain, <a href="#sect_II_2_3">ii. 2. 3</a>.</p> + <p>—— extremities of form the whole system, <a href="#sect_XXXVII_3">xxxvii. 3</a>.</p> + <p>—— are not changed with age, <a href="#sect_XXXVII_4">xxxvii. 4</a>.</p> + <p>Nervous pains defined, <a href="#sect_XXXIV_1_1">xxxiv. 1. 1</a>.</p> + <p>Number defined, <a href="#sect_XIV_2_2">xiv. 2. 2</a>.</p> + <p>Nutriment for the embryon, <a href="#sect_XXXIX_5_2">xxxix. 5. 2</a>.</p> + <p>Nutrition owing to stimulus, <a href="#sect_XXXVII_3">xxxvii. 3</a>.</p> + <p>—— by animal selection, <a href="#sect_XXXVII_3">xxxvii. 3</a>.</p> + <p>—— when the fibres are elongated, <a href="#sect_XXXVII_3">xxxvii. 3</a>.</p> + <p>—— like inflammation, <a href="#sect_XXXVII_3">xxxvii. 3</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>O.</b></p> + </div> + + <div class="stanza"> + <p>Objects long viewed become faint, <a href="#sect_III_3_2">iii. 3. 2</a>.</p> + <p>Ocular spectra, <a href="#sect_XL">xl</a>.</p> + <p>Oil externally in diabætes, <a href="#sect_XXIX_4">xxix. 4</a>.</p> + <p>Old age from inirritability, <a href="#sect_XXXVII">xxxvii</a>.</p> + <p>Opium is stimulant, <a href="#sect_XXXII_2_2">xxxii. 2. 2</a>.</p> + <p>—— promotes absorption after evacuation, <a href="#sect_XXXIII_3_1">xxxiii. 3. 1</a>.</p> + <p>—— in increasing doses, <a href="#sect_XII_3_1">xii. 3. 1</a>.</p> + <p>Organs of sense, <a href="#sect_II_2_5">ii. 2. 5</a>. and <a href="#sect_II_2_6">6</a>.</p> + <p>Organs when destroyed cease to produce ideas, <a href="#sect_III_4_4">iii. 4. 4</a>.</p> + <p>Organic particles of Buffon, <a href="#sect_XXXVII_3">xxxvii. 3</a>. <a href="#sect_XXXIX_3_3">xxxix. 3. 3</a>.</p> + <p>Organ-pipes, <a href="#sect_XX_7">xx. 7</a>.</p> + <p>Oxygenation of the blood, <a href="#sect_XXXVIII">xxxviii</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>P.</b></p> + </div> + + <div class="stanza"> + <p>Pain from excess and defect of motion, <a href="#sect_IV_5">iv. 5</a>. <a href="#sect_XII_5_3">xii. 5. 3</a>. <a href="#sect_XXXIV_1">xxxiv. 1</a>. <a href="#sect_XXXV_2_1">xxxv. 2. 1</a>.</p> + <p>—— not felt during exertion, <a href="#sect_XXXIV_1_2">xxxiv. 1. 2</a>.</p> + <p>—— from greater contraction of fibres, <a href="#sect_XII_1_6">xii. 1. 6</a>.</p> + <p>—— from accumulation of sensorial power, <a href="#sect_XII_5_3">xii. 5. 3</a>.</p> + <p>—— from light, pressure, heat, caustics, <a href="#sect_XIV_9">xiv. 9</a>.</p> + <p>—— in epilepsy, <a href="#sect_XXXV_2_1">xxxv. 2. 1</a>.</p> + <p>—— distant from its cause, <a href="#sect_XXIV_2_8">xxiv. 2. 8</a>.</p> + <p>—— from stone in the bladder, <a href="#sect_XXXV_2_1">xxxv. 2. 1</a>.</p> + <p>—— of head and back from defect, <a href="#sect_XXXII_3">xxxii. 3</a>.</p> + <p>—— from a gall-stone, <a href="#sect_XXXV_2_1">xxxv. 2. 1</a>. <a href="#sect_XXV_17">xxv. 17</a>.</p> + <p>—— of the stomach in gout, <a href="#sect_XXV_17">xxv. 17</a>.</p> + <p>—— of shoulder in hepatitis, <a href="#sect_XXXV_2_4">xxxv. 2. 4</a>.</p> + <p>—— produces volition, <a href="#sect_IV_6">iv. 6</a>.</p> + <p>Paleness in cold fit, <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + <p>Palsies explained, <a href="#sect_XXXIV_1_7">xxxiv. 1. 7</a>.</p> + <p>Paralytic limbs stretch from irritation, <a href="#sect_VII_1_3">vii. 1. 3</a>.</p> + <p>—— patients move their sound limb much, <a href="#sect_XII_5_1">xii. 5. 1</a>.</p> + <p>Paralysis from great exertion, <a href="#sect_XII_4_6">xii. 4. 6</a>.</p> + <p>—— from less exertion, <a href="#sect_XII_5_6">xii. 5. 6</a>.</p> + <p>—— of the lacteals, <a href="#sect_XXVIII">xxviii</a>.</p> + <p>—— of the liver, <a href="#sect_XXX_1_4">xxx. 1. 4</a>.</p> + <p>—— of the right arm, why, <a href="#sect_XXXIV_1_7">xxxiv. 1. 7</a>.</p> + <p>—— of the veins, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>Particles of matter will not approach, <a href="#sect_XII_1_1">xii. 1. 1</a>.</p> + <p>Passions, <a href="#sect_XI_2_2">xi. 2. 2</a>.</p> + <p>—— connate, <a href="#sect_XVI_1">xvi. 1</a>.</p> + <p>Pecking of chickens, <a href="#sect_XVI_4">xvi. 4</a>.</p> + <p>Perception defined, <a href="#sect_II_2_8">ii. 2. 8</a>. <a href="#sect_XV_3_1">xv. 3. 1</a>.</p> + <p>Periods of agues, how formed, <a href="#sect_XXXII_3_4">xxxii. 3. 4</a>.</p> + <p>—— of diseases, <a href="#sect_XXXVI">xxxvi</a>.</p> + <p>—— of natural actions and of diseased actions, <a href="#sect_XXXVI">xxxvi</a>.</p> + <p>Perspiration in fever-fits, <a href="#sect_XXXII_9">xxxii. 9</a>. See Sweat.</p> + <p>Petechiæ, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>Pigeons secrete milk in their stomachs, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + <p>Piles, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>Placenta a pulmonary organ, <a href="#sect_XXXVIII_2">xxxviii. 2</a>.</p> + <p>Pleasure of life, <a href="#sect_XXXIII_1">xxxiii. 1</a>. <a href="#sect_XXXIX_5">xxxix. 5</a>.</p> + <p>—— from greater fibrous contractions, <a href="#sect_XII_1_6">xii. 1. 6</a>.</p> + <p>—— what kind causes laughter, <a href="#sect_XXXIV_1_4">xxxiv. 1. 4</a>.</p> + <p>—— what kind causes sleep, <a href="#sect_XXXIV_1_4">xxxiv. 1. 4</a>.</p> + <p>Pleurisy, periods of, <a href="#sect_XXXVI_3_7">xxxvi. 3. 7</a>.</p> + <p>—— cause of, <a href="#sect_XXXV_2_3">xxxv. 2. 3</a>.</p> + <p>Prometheus, story of, <a href="#sect_XXX_3">xxx. 3</a>.</p> + <p>Prostration of strength in fevers, <a href="#sect_XII_4_1">xii. 4. 1</a>.</p> + <p>Pupils of the eyes large, <a href="#sect_XXXI_1">xxxi. 1</a>.</p> + <p>Pulse quick in fevers with debility, <a href="#sect_XII_1_4">xii. 1. 4</a>. <a href="#sect_XII_5_4">xii. 5. 4</a>. <a href="#sect_XXXII_2_1">xxxii. 2. 1</a>.</p> + <p>—— in fevers with strength, <a href="#sect_XXXII_2">xxxii. 2</a>.</p> + <p>—— from defect of blood, <a href="#sect_XXXII_2_3">xxxii. 2. 3</a>. <a href="#sect_XII_1_4">xii. 1. 4</a>.</p> + <p>—— weak from emetics, <a href="#sect_XXV_17">xxv. 17</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>Q.</b></p> + </div> + + <div class="stanza"> + <p>Quack advertisements injurious. Preface.</p> + <p>Quadrupeds have no sanguiferous lochia, <a href="#sect_XXXVIII_2">xxxviii. 2</a>.</p> + <p>—— have nothing similar to the yolk of egg, <a href="#sect_XXXIX_1">xxxix. 1</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>R.</b></p> + </div> + + <div class="stanza"> + <p>Rhaphania, periods of, <a href="#sect_XXXVI_3_9">xxxvi. 3. 9</a>.</p> + <p>Reason, <a href="#sect_IX_1_2">ix. 1. 2</a>. <a href="#sect_XV_3">xv. 3</a>.</p> + <p>Reasoning, <a href="#sect_XV_3">xv. 3</a>.</p> + <p>Recollection, <a href="#sect_II_2_10">ii. 2. 10</a>. <a href="#sect_IX_1_2">ix. 1. 2</a>. <a href="#sect_XV_2_3">xv. 2. 3</a>.</p> + <p>Relaxation and bracing, <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + <p>Repetition, why agreeable, <a href="#sect_XII_3_3">xii. 3. 3</a>. <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>Respiration affected by attention, <a href="#sect_XXXVI_2_1">xxxvi. 2. 1</a>.</p> + <p>Restlessness in fevers, <a href="#sect_XXXIV_1_2">xxxiv. 1. 2</a>.</p> + <p>Retrograde motions, <a href="#sect_XII_5_5">xii. 5. 5</a>. <a href="#sect_XXV_6">xxv. 6</a>. <a href="#sect_XXIX_11">xxix. 11</a>.</p> + <p>—— of the stomach, <a href="#sect_XXV_6">xxv. 6</a>.</p> + <p>—— of the skin, <a href="#sect_XXV_9">xxv. 9</a>.</p> + <p>—— of fluids, how distinguished, <a href="#sect_XXIX_8">xxix. 8</a>.</p> + <p>—— how caused, <a href="#sect_XXIX_11_5">xxix. 11. 5</a>.</p> + <p>—— vegetable motions, <a href="#sect_XXIX_9">xxix. 9</a>.</p> + <p>Retina is fibrous, <a href="#sect_III_2">iii. 2</a>. <a href="#sect_XL_1">xl. 1</a>.</p> + <p>—— is active in vision, <a href="#sect_III_3">iii. 3</a>. <a href="#sect_XL_1">xl. 1</a>.</p> + <p>—— excited into spasmodic motions, <a href="#sect_XL_7">xl. 7</a>.</p> + <p>—— is sensible during sleep, <a href="#sect_XVIII_5">xviii. 5</a>. <a href="#sect_XIX_8">xix. 8</a>.</p> + <p>Reverie, <a href="#sect_XIX_1">xix. 1</a>. <a href="#sect_XXXIV_3">xxxiv. 3</a>.</p> + <p>—— case of a sleep-walker, <a href="#sect_XIX_2">xix. 2</a>.</p> + <p>—— is an epileptic disease, <a href="#sect_XIX_9">xix. 9</a>.</p> + <p>Rhymes in poetry, why agreeable, <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>Rheumatism, three kinds of, <a href="#sect_XXVI_3">xxvi. 3</a>.</p> + <p>Rocking young children, <a href="#sect_XXI_3">xxi. 3</a>.</p> + <p>Ruminating animals, <a href="#sect_XXV_1">xxv. 1</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>S.</b></p> + </div> + + <div class="stanza"> + <p>Saliva produced by mercury, <a href="#sect_XXIV_1">xxiv. 1</a>.</p> + <p>—— by food, <a href="#sect_XXIV_1_1">xxiv. 1. 1</a>.</p> + <p>—— by ideas, <a href="#sect_XXIV_1_2">xxiv. 1. 2</a>. and <a href="#sect_XXIV_1_5">5</a>.</p> + <p>—— by disordered volition, <a href="#sect_XXIV_1_7">xxiv. 1. 7</a>.</p> + <p>Schirrous tumours revive, <a href="#sect_XII_2_2">xii. 2. 2</a>.</p> + <p>Screaming in pain, <a href="#sect_XXXIV_1_3">xxxiv. 1. 3</a>.</p> + <p>Scrophula, its temperament, <a href="#sect_XXXI_1">xxxi. 1</a>.</p> + <p>—— <a href="#sect_XXVIII_2">xxviii. 2</a>. <a href="#sect_XXXIX_4_5">xxxix. 4. 5</a>.</p> + <p>Scurvy of the lungs, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>Sea-sickness, <a href="#sect_XX_4">xx. 4</a>.</p> + <p>—— stopped by attention, <a href="#sect_XX_5">xx. 5</a>.</p> + <p>Secretion, <a href="#sect_XXXIII_1">xxxiii. 1</a>. <a href="#sect_XXXVII">xxxvii</a>.</p> + <p>—— increased during sleep, <a href="#sect_XVIII_16">xviii. 16</a>.</p> + <p>Seeds require oxygenation, <a href="#sect_XXXVIII_2">xxxviii. 2</a>.</p> + <p>Sensation defined, <a href="#sect_II_2_9">ii. 2. 9</a>. <a href="#sect_V_2">v. 2</a>. <a href="#sect_XXXIX_8_4">xxxix. 8. 4</a>.</p> + <p>—— diseases of, <a href="#sect_XXXIII">xxxiii</a>.</p> + <p>—— from fibrous contractions, <a href="#sect_IV_5">iv. 5</a>. <a href="#sect_XII_1_6">xii. 1. 6</a>.</p> + <p>—— in an amputated limb, <a href="#sect_III_6_3">iii. 6. 3</a>.</p> + <p>—— affects the whole sensorium, <a href="#sect_XI_2">xi. 2</a>.</p> + <p>—— produces volition, <a href="#sect_IV_6">iv. 6</a>.</p> + <p>Sensibility increases during sleep, <a href="#sect_XVIII_15">xviii. 15</a>.</p> + <p>Sensitive motions, <a href="#sect_VIII">viii</a>. <a href="#sect_XXXIII_2">xxxiii. 2</a>. <a href="#sect_XXXIV_1">xxxiv. 1</a>.</p> + <p>—— fevers of two kinds, <a href="#sect_XXXIII_1_2">xxxiii. 1. 2</a>.</p> + <p>—— ideas, <a href="#sect_XV_2_2">xv. 2. 2</a>.</p> + <p>Sensorium defined, <a href="#sect_II_2_1">ii. 2. 1</a>.</p> + <p>Senses correct one another, <a href="#sect_XVIII_7">xviii. 7</a>.</p> + <p>—— distinguished from appetites, <a href="#sect_XXXIV_1_1">xxxiv. 1. 1</a>.</p> + <p>Sensorial power. See Spirit of Animation.</p> + <p>—— great expence of in the vital motions, <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + <p>—— two kinds of excited in sensitive fevers, <a href="#sect_XXXIII_1_3">xxxiii. 1. 3</a>.</p> + <p>—— powers defined, <a href="#sect_V_1">v. 1</a>.</p> + <p>—— motions distinguished from fibrous motions, <a href="#sect_V_3">v. 3</a>.</p> + <p>—— not much, accumulated in sleep, <a href="#sect_XVIII_2">xviii. 2</a>.</p> + <p>—— powers, accumulation of, <a href="#sect_XII_5_1">xii. 5. 1</a>.</p> + <p>—— exhaustion of, <a href="#sect_XII_4_1">xii. 4. 1</a>.</p> + <p>—— wasted below natural in hot fits, <a href="#sect_XXXII_9_3">xxxii. 9. 3</a>.</p> + <p>—— less exertion of produces pain, <a href="#sect_XII_5_3">xii. 5. 3</a>.</p> + <p>—— less quantity of it, <a href="#sect_XII_5_4">xii. 5. 4</a>.</p> + <p>Sensual motions distinguished from muscular, <a href="#sect_II_2_7">ii. 2. 7</a>.</p> + <p>Sex owing to the imagination of the father, <a href="#sect_XXXIX_7_6">xxxix. 7. 6</a>. <a href="#sect_XXXIX_6_3">xxxix. 6. 3</a>. <a href="#sect_XXXIX_6_7">xxxix. 6. 7</a>. <a href="#sect_XXXIX_5">xxxix. 5</a>.</p> + <p>Shingles from inflamed kidney, <a href="#sect_XXXV_2_2">xxxv. 2. 2</a>.</p> + <p>Shoulders broad, <a href="#sect_XXXI_1">xxxi. 1</a>. <a href="#sect_XXXIX_7_6">xxxix. 7. 6</a>.</p> + <p>Shuddering from cold, <a href="#sect_XXXIV_1_1">xxxiv. 1. 1</a>. and <a href="#sect_XXXIV_1_2">2</a>.</p> + <p>Sight, its accuracy in men, <a href="#sect_XVI_6">xvi. 6</a>.</p> + <p>Skin, skurf on it, <a href="#sect_XXVI_1">xxvi. 1</a>.</p> + <p>Sleep suspends volition, <a href="#sect_XVIII_1">xviii. 1</a>.</p> + <p>—— defined, <a href="#sect_XVIII_21">xviii. 21</a>.</p> + <p>—— remote causes, <a href="#sect_XVIII_20">xviii. 20</a>.</p> + <p>—— sensation continues in it, <a href="#sect_XVIII_2">xviii. 2</a>.</p> + <p>—— from food, <a href="#sect_XXI_1">xxi. 1</a>.</p> + <p>—— from rocking, uniform sounds, <a href="#sect_XXI_1">xxi. 1</a>.</p> + <p>—— from wine and opium, <a href="#sect_XXI_3">xxi. 3</a>.</p> + <p>—— why it invigorates, <a href="#sect_XII_5_1">xii. 5. 1</a>.</p> + <p>—— pulse slower and fuller, <a href="#sect_XXXII_2_2">xxxii. 2. 2</a>.</p> + <p>—— interrupted, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>—— from breathing less oxygene, <a href="#sect_XVIII_20">xviii. 20</a>.</p> + <p>—— from being whirled on a millstone, <a href="#sect_XVIII_20">xviii. 20</a>.</p> + <p>—— from application of cold, <a href="#sect_XVIII_20">xviii. 20</a>.</p> + <p>—— induced by regular hours, <a href="#sect_XXXVI_2_2">xxxvi. 2. 2</a>.</p> + <p>Sleeping animals, <a href="#sect_XII_2_2">xii. 2. 2</a>.</p> + <p>Sleep-walkers. See Reverie, <a href="#sect_XIX_1">xix. 1</a>.</p> + <p>Small-pox, <a href="#sect_XXXIII_2_6">xxxiii. 2. 6</a>. <a href="#sect_XXXIX_6_1">xxxix. 6. 1</a>.</p> + <p>—— eruption first on the face, why, <a href="#sect_XXXV_1_1">xxxv. 1. 1</a>. <a href="#sect_XXXIII_2_10">xxxiii. 2. 10</a>.</p> + <p>—— the blood will not infect, <a href="#sect_XXXIII_2_10">xxxiii. 2. 10</a>.</p> + <p>—— obeys lunations, <a href="#sect_XXXVI_4">xxxvi. 4</a>.</p> + <p>Smell, <a href="#sect_XIV_5">xiv. 5</a>. <a href="#sect_XVI_5">xvi. 5</a>.</p> + <p>Smiling, origin of, <a href="#sect_XVI_8_4">xvi. 8. 4</a>.</p> + <p>Solidity, <a href="#sect_XIV_2_1">xiv. 2. 1</a>.</p> + <p>Somnambulation. See Reverie, <a href="#sect_XIX_1">xix. 1</a>.</p> + <p>Space, <a href="#sect_XIV_2_2">xiv. 2. 2</a>.</p> + <p>Spasm, doctrine of, <a href="#sect_XXXII_10">xxxii. 10</a>.</p> + <p>Spectra, ocular, <a href="#sect_XL">xl</a>.</p> + <p>—— mistaken for spectres, <a href="#sect_XL_2">xl. 2</a>.</p> + <p>—— vary from long inspection, <a href="#sect_III_3_5">iii. 3. 5</a>.</p> + <p>Spirit of animation. See Sensorial Power.</p> + <p>—— of animation causes fibrous contraction, <a href="#sect_IV_2">iv. 2</a>. <a href="#sect_II_2_1">ii. 2. 1</a>. <a href="#sect_XIV_2_4">xiv. 2. 4</a>.</p> + <p>—— possesses solidity, figure, and other properties of matter, <a href="#sect_XIV_2_4">xiv. 2. 4</a>.</p> + <p>Spirits and angels, <a href="#sect_XIV_2_4">xiv. 2. 4</a>.</p> + <p>Stammering explained, <a href="#sect_XVII_1_10">xvii. 1. 10</a>. <a href="#sect_XVII_2_10">xvii. 2. 10</a>.</p> + <p>Stimulus defined, <a href="#sect_II_2_13">ii. 2. 13</a>. <a href="#sect_IV_4">iv. 4</a>. <a href="#sect_XII_2_1">xii. 2. 1</a>.</p> + <p>—— of various kinds, <a href="#sect_XI_1">xi. 1</a>.</p> + <p>—— with lessened effect, <a href="#sect_XII_3_1">xii. 3. 1</a>.</p> + <p>—— with greater effect, <a href="#sect_XII_3_3">xii. 3. 3</a>.</p> + <p>—— ceases to produce sensation, <a href="#sect_XII_3_6">xii. 3. 6</a>.</p> + <p>Stomach and intestines, <a href="#sect_XXV">xxv</a>.</p> + <p>—— inverted by great stimulus, <a href="#sect_XXV_6">xxv. 6</a>.</p> + <p>—— its actions decreased in vomiting, <a href="#sect_XXXV_1_3">xxxv. 1. 3</a>.</p> + <p>—— a blow on it occasions death, <a href="#sect_XXV_17">xxv. 17</a>.</p> + <p>Stools black, <a href="#sect_XXVII_2">xxvii. 2</a>.</p> + <p>Strangury, <a href="#sect_XXXV_2_1">xxxv. 2. 1</a>.</p> + <p>Sucking before nativity, <a href="#sect_XVI_4">xvi. 4</a>.</p> + <p>Suckling children, sense of, <a href="#sect_XIV_8">xiv. 8</a>.</p> + <p>Suggestion defined, <a href="#sect_II_2_10">ii. 2. 10</a>. <a href="#sect_XV_2_4">xv. 2. 4</a>.</p> + <p>Sun and moon, their influence, <a href="#sect_XXXII_6">xxxii. 6</a>.</p> + <p>Surprise, <a href="#sect_XVII_3_7">xvii. 3. 7</a>. <a href="#sect_XVIII_17">xviii. 17</a>.</p> + <p>Suspicion attends madness, <a href="#sect_XXXIV_2_4">xxxiv. 2. 4</a>.</p> + <p>Swallowing, act of, <a href="#sect_XXV_1">xxv. 1</a>. <a href="#sect_XVI_4">xvi. 4</a>.</p> + <p>Sweat, cold, <a href="#sect_XXV_9">xxv. 9</a>. <a href="#sect_XXIX_6">xxix. 6</a>.</p> + <p>—— in hot fit of fever, <a href="#sect_XXXII_9">xxxii. 9</a>.</p> + <p>—— in a morning, why, <a href="#sect_XVIII_15">xviii. 15</a>.</p> + <p>Sweaty hands cured by lime, <a href="#sect_XXIX_4_9">xxix. 4. 9</a>.</p> + <p>Swinging and rocking, why agreeable, <a href="#sect_XXI_3">xxi. 3</a>.</p> + <p>Sympathy, <a href="#sect_XXXV_1">xxxv. 1</a>.</p> + <p>Syncope, <a href="#sect_XII_7_1">xii. 7. 1</a>. <a href="#sect_XXXIV_1_6">xxxiv. 1. 6</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>T.</b></p> + </div> + + <div class="stanza"> + <p>Tædium vitæ. See Ennui.</p> + <p>Tape-worm, <a href="#sect_XXXIX_2_3">xxxix. 2. 3</a>.</p> + <p>Taste, sense of, <a href="#sect_XIV_5">xiv. 5</a>.</p> + <p>Tears, secretion of, <a href="#sect_XXIV">xxiv</a>.</p> + <p>—— from grief, <a href="#sect_XVI_8_2">xvi. 8. 2</a>.</p> + <p>—— from tender pleasure, <a href="#sect_XVI_8_3">xvi. 8. 3</a>.</p> + <p>—— from stimulus of nasal duct, <a href="#sect_XVI_8">xvi. 8</a>. <a href="#sect_XXIV_2_4">xxiv. 2. 4</a>.</p> + <p>—— by volition, <a href="#sect_XXIV_2_6">xxiv. 2. 6</a>.</p> + <p>Teeth decaying cause headachs, <a href="#sect_XXXV_2_1">xxxv. 2. 1</a>.</p> + <p>Temperaments, <a href="#sect_XXXI">xxxi</a>.</p> + <p>Theory of medicine, wanted. Preface.</p> + <p>Thirst, sense of, <a href="#sect_XIV_8">xiv. 8</a>.</p> + <p>—— why in dropsies, <a href="#sect_XXIX_5">xxix. 5</a>.</p> + <p>Tickle themselves, children cannot, <a href="#sect_XVII_3_5">xvii. 3. 5</a>.</p> + <p>Tickling, <a href="#sect_XIV_9">xiv. 9</a>.</p> + <p>Time, <a href="#sect_XIV_2_2">xiv. 2. 2</a>. <a href="#sect_XVIII_12">xviii. 12</a>.</p> + <p>—— lapse of, <a href="#sect_XV_3_6">xv. 3. 6</a>.</p> + <p>—— poetic and musical, why agreeable, <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>—— dramatic, <a href="#sect_XVIII_12">xviii. 12</a>.</p> + <p>Tooth-edge, <a href="#sect_XVI_10">xvi. 10</a>. <a href="#sect_III_4_3">iii. 4. 3</a>. <a href="#sect_XXII_3_3">xxii. 3. 3</a>.</p> + <p>Touch, sense of, <a href="#sect_XIV_2_1">xiv. 2. 1</a>.</p> + <p>—— liable to vertigo, <a href="#sect_XXI_9">xxi. 9</a>.</p> + <p>—— of various animals, <a href="#sect_XVI_6">xvi. 6</a>.</p> + <p>Trains of motions inverted, <a href="#sect_XII_5_5">xii. 5. 5</a>.</p> + <p>Transfusion of blood in nervous fever, <a href="#sect_XXXII_4">xxxii. 4</a>.</p> + <p>Translations of matter, <a href="#sect_XXIX_7">xxix. 7</a>.</p> + <p>Typhus, best quantity of stimulus in, <a href="#sect_XII_7_8">xii. 7. 8</a>.</p> + <p>—— periods of observe lunar days, <a href="#sect_XXXII_6">xxxii. 6</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>U.</b></p> + </div> + + <div class="stanza"> + <p>Ulcers, art of healing, <a href="#sect_XXXIII_3_2">xxxiii. 3. 2</a>.</p> + <p>—— of the lungs, why difficult to heal, <a href="#sect_XXVIII_2">xxviii. 2</a>.</p> + <p>Uniformity in the fine arts, why agreeable, <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>Urine pale in intoxication, <a href="#sect_XXI_6">xxi. 6</a>.</p> + <p>—— paucity of in anasarca, why, <a href="#sect_XXIX_5">xxix. 5</a>.</p> + <p>—— its passage from intestines to bladder, <a href="#sect_XXIX_3">xxix. 3</a>.</p> + <p>—— copious during sleep, <a href="#sect_XVIII_15">xviii. 15</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>V.</b></p> + </div> + + <div class="stanza"> + <p>Variation, perpetual, of irritability, <a href="#sect_XII_2_1">xii. 2. 1</a>.</p> + <p>Vegetable buds are inferior animals, <a href="#sect_XIII_1">xiii. 1</a>.</p> + <p>—— exactly resemble their parents, <a href="#sect_XXXIX">xxxix</a>.</p> + <p>—— possess sensation and volition, <a href="#sect_XIII_2">xiii. 2</a>.</p> + <p>—— have associate and retrograde motions, <a href="#sect_XIII_4">xiii. 4</a>. <a href="#sect_XXIX_9">xxix. 9</a>.</p> + <p>—— their anthers and stigmas are alive, <a href="#sect_XIII_5">xiii. 5</a>.</p> + <p>—— have organs of sense and ideas, <a href="#sect_XIII_5">xiii. 5</a>.</p> + <p>—— contend for light and air, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + <p>—— duplicature of their flowers, <a href="#sect_XXXIX_4_4">xxxix. 4. 4</a>.</p> + <p>Veins are absorbents, <a href="#sect_XXVII_1">xxvii. 1</a>.</p> + <p>—— paralysis of, <a href="#sect_XXVII_1">xxvii. 1</a>.</p> + <p>Venereal orgasm of brutes, <a href="#sect_XXXII_6">xxxii. 6</a>.</p> + <p>Venesection in nervous pains, <a href="#sect_XXXII_5_4">xxxii. 5. 4</a>.</p> + <p>Verbs of three kinds, <a href="#sect_XV_3_4">xv. 3. 4</a>.</p> + <p>Verses, their measure, <a href="#sect_XXII_2">xxii. 2</a>.</p> + <p>Vertigo, <a href="#sect_XX">xx</a>.</p> + <p>—— defined, <a href="#sect_XX_11">xx. 11</a>.</p> + <p>—— in looking from a tower, <a href="#sect_XX_1">xx. 1</a>.</p> + <p>—— in a ship at sea, <a href="#sect_XX_4">xx. 4</a>.</p> + <p>—— of all the senses, <a href="#sect_XXI_9">xxi. 9</a>.</p> + <p>—— by intoxication, <a href="#sect_XXXV_1_2">xxxv. 1. 2</a>.</p> + <p>Vibratory motions perceived after sailing, <a href="#sect_XX_5">xx. 5</a>. <a href="#sect_XX_10">xx. 10</a>.</p> + <p>Vinegar makes the lips pale, <a href="#sect_XXVII_1">xxvii. 1</a>.</p> + <p>Vis medicatrix of nature, <a href="#sect_XXXIX_4_7">xxxix. 4. 7</a>.</p> + <p>Vision, sense of, <a href="#sect_XIV_3">xiv. 3</a>.</p> + <p>Volition defined, <a href="#sect_V_2">v. 2</a>. <a href="#sect_XXXIV_1">xxxiv. 1</a>.</p> + <p>—— affects the whole sensorium, <a href="#sect_XI_2">xi. 2</a>.</p> + <p>—— diseases of, <a href="#sect_XXXIV">xxxiv</a>.</p> + <p>Voluntarity, <a href="#sect_XI_2_4">xi. 2. 4</a>.</p> + <p>Voluntary motions, <a href="#sect_IX">ix</a>. <a href="#sect_XXXIV_1">xxxiv. 1</a>.</p> + <p>Voluntary ideas, <a href="#sect_XV_2_3">xv. 2. 3</a>.</p> + <p>—— criterion of, <a href="#sect_XI_2_3">xi. 2. 3</a>. <a href="#sect_XXXIV_1">xxxiv. 1</a>.</p> + <p>Vomiting from vertigo, <a href="#sect_XX_8">xx. 8</a>.</p> + <p>—— from drunkenness, <a href="#sect_XX_8">xx. 8</a>. <a href="#sect_XXI_6">xxi. 6</a>.</p> + <p>—— by intervals, <a href="#sect_XXV_8">xxv. 8</a>.</p> + <p>—— by voluntary efforts, <a href="#sect_XXV_6">xxv. 6</a>.</p> + <p>—— of two kinds, <a href="#sect_XXXV_1_3">xxxv. 1. 3</a>.</p> + <p>—— in cold fit of fever, <a href="#sect_XXXII_9_1">xxxii. 9. 1</a>.</p> + <p>—— stopped by quicksilver, <a href="#sect_XXV_16">xxv. 16</a>.</p> + <p>—— weakens the pulse, <a href="#sect_XXV_17">xxv. 17</a>.</p> + </div> + + <div class="stanza"> + <p class="i16"><b>W.</b></p> + </div> + + <div class="stanza"> + <p>Waking, how, <a href="#sect_XVIII_14">xviii. 14</a>.</p> + <p>Walking, how learnt, <a href="#sect_XVI_3">xvi. 3</a>.</p> + <p>Warmth in sleep, why, <a href="#sect_XVIII_15">xviii. 15</a>.</p> + <p>Weakness defined, <a href="#sect_XII_1_3">xii. 1. 3</a>. <a href="#sect_XII_2_1">xii. 2. 1</a>. <a href="#sect_XXXII_3_2">xxxii. 3. 2</a>.</p> + <p>—— cure of, <a href="#sect_XII_7_8">xii. 7. 8</a>.</p> + <p>—— See Debility.</p> + <p>Wit producing laughter, <a href="#sect_XXXIV_1_4">xxxiv. 1. 4</a>.</p> + <p>World generated, <a href="#sect_XXXIX_4_8">xxxix. 4. 8</a>.</p> + </div> + </div> + <br clear="all" /> +<hr /> + +<p class="center" style="margin-top: 2em;">END OF THE FIRST VOLUME.</p> + + + + + + + + +<pre> + + + + + +End of the Project Gutenberg EBook of Zoonomia, 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