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UNITED STATES OF AMERICA
*  ME
WASHINGTON,  D. C.
GPO  16—67244-1 
 
 
*7
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OUTLINES
/c.
OF
ANATOMY   AND  PHYSIOLOGY,
TRANSLATED FROM THE FRENCH
OF
                         V

         H.  MILNE  EDWARDS,

DOCTOR OF MEDICINE, PROFESSOR OF NATURAL HISTORY AT THE ROYAL
    COLLEGE OF HENRY IV., AND AT THE CENTRAL SCHOOL
         OF ARTS AND MANUFACTURES, IN PARIS.
By J. F. W. LANE, M. D.

        BOSTON:

CHARLES C. LITTLE AND JAMES BROWN.
MDCCCXLI.
\<H 
                   nil
           K  ■.      10'  2/   »■$,
       Entered according to Act of Congress, in the year 184],
          By Charles C. Little and James Brown,
In the Clerk's office of the District Court of the District of Massachusetts.
         BOSTON:

PRINTED BY FREEMAN AND BOLLES,
WASHINGTON STREET. 
TRANSLATOR'S  PREFACE.
  The subject of Anatomy and Physiology, until quite recently,
was never presented to the scholar, or to the public in general.
Previous to that period its study had been  limited to medical
men only, and  a certain degree of opprobrium even was at-
tached to those engaged in Anatomical pursuits.  But such a
change has been gradually wrought in public opinion  upon
this subject, that now no system  of education is considered
complete, without some acquaintance  with  the human  form
and structure  be included.  The prejudice is fast passing away,
nay has already passed, which has so long kept back from the
many a knowledge of the healthy  exercise of their organs and
functions; and which no doubt in a great  degree prevented
more rapid advances from being  made by physicians  them-
selves in the intimate structure of  the organs.   Upon the im-
portance of this study to the medical student it were needless
to enlarge—the information obtained from it  finds daily use
with all, whether  in  diet, ventilation, clothing, broken bones,
running, walking: not an act of the body can be performed
without calling in question  some point  of physiology.   But 
IV
TRANSLATOR'S  PREFACE.
let us bear in mind, that the present is strictly a physiological
view of man, and no where does our author so much as pre-
sent a glimmer even of his psychological  state.  This limited
view may however serve as a stepping stone to the other ; and
from this point how vast, how illimitable the field of Natural
History appears.
  There are many excellent works upon the same subject, but
they are too minute and abound  in technicalities; to supply
the deficiency arising from this cause, and  at the same time
furnish  the  medical  student  with an  elementary work, has
been my object  in  this translation.  In the language of the
author,  " the age and characters of some  of my readers has,
perhaps, made it necessary for me to pass rapidly over certain
functions; but I  am not aware of any important omissions in
this sketch of the phenomena constituting life.  My aim has
been to be clear and concise, and from the nature of my work
I have been compelled  to limit myself to facts, and  to  pass
over in silence the opinions and hypotheses, with the discus-
sion of which our treatises  on physiology are  so  filled."  It
was my intention to  have added a series of notes, but upon
a reperusal of the work they do  not seem so necessary  as  at
first; the few remarks which  have been appended  will  not, I
trust, be found wholly useless. 
TABLE  OF  CONTENTS.
                                                         Page
Preliminary Remarks,    .     .     .    .    .     .     1 —19

General Characters of Living Beings,      .     .      3 — 8
  Anatomical and physiological characters common to animals and
    vegetables, 3— Nutrition, 3 — Proofs of  the existence  of  the
    nutritive movement, 4 — Duration and origin, 6 — Structure,
    6 — Chemical composition,  7 — Review  of the characters of
    organized beings, 8.

General Characters of Animals,    .     .     .     .    8, 9
  Chemical composition, 8 — Faculties more varied than in vegeta-
    bles, 9 — Definition of the word animal, 9.

The Functions of Animals and their Organs,    .   9 — 16
  Organs, 9 — Apparatus, 10 — Function, 10 — Object of different
    functions, 10 — Classification of the functions, 10 — Difference
    between the functions of different animals, 10 — Division of the
    vital labor,  11—Consequences of this  law, 12 — Effects of
    mutilations, 12 — Experiments upon fresh water  polypi, 13 —
    Experiments upon earth-worms,  14 — Localization of the differ-
    ent functions  in  the superior animals, 16 — Examples to be
    chosen for the study of these functions, 16. 
VI
CONTENTS.
Organic Tissues,   ....••■     *"    1J
  Materials forming the organs, 16—Muscular tissue, 17 —Ner-
     vous tissue, 17 —Cellular  tissue, 17 —Mucous, fibrous,  bony
     tissues, etc., 19 — Elementary structure of the tissues,  19.

The Functions of Nutrition,          •     •     •    20   151

The Nutritive Fluids, or  the Blood,      .     .    21—33
  Liquids contained in the  body, 21 —Effects of desiccation, 21 —
     Experiments upon the vibrio, 21 —Relative proportions of the
     fluids and solids, 23 — Nature of the fluids,  23 — Blood, 23 —
     White blood, 24 —Red blood, 24 —Globules of the blood,  24
     — Form of the globules, 25—Structure of the globules, 25 —
     Coagulation of the blood,  26 — Chemical composition,  27 —
     Proportions of the serum and globules, 28—Uses of the glo-
     bules,  29 — Effects of hemorrhage,  29 — Transfusion,  29 —
     Influence of the form of the globules, 30 — Application, 31 —
     Influence of the blood  upon nutrition, 32 — Influence of the
     organs upon the blood, 32— Arterial and venous blood, 32.

Circulation of the Blood,   .     .    .     .     .     33 — 41
  Necessity of  a circulatory movement, 33 — Apparatus of the cir-
     culation, 34 — Heart, 34 — Vessels,  35 — Arteries  and veins,
     35—Capillary vessels, 36 — Discovery of the circulation, 36 —
     Proofs of the  existence of the  circulation,  38 — Greater and
     less circulation, 39 — Direction of the  blood, 39; — Crustace-
     ous and mollusca, 39 — Fishes, 40 — Reptiles, 40 — Mammi-
     ferao and birds, 40.

Apparatus  of  Circulation  in Man,    .          .    4\__46
  Heart, 41 — Aorta, 43 — Veins, 44 — Vena-porta, 44 — Pulmo-
     nary artery, 44 — Pulmonary veins, 45 — Structure of the blood
     vessels, 45.

Mechanism of the Circulation,   .     .     .     .    46__54
  Contractions  of  the heart, 46 — Course of the blood in the arte-
     ries, 48 — Influence of  the  arterial coats,  49 — Pulse,  50__
     Rapidity of the blood in the different parts of the body, 50__ 
CONTENTS.
Vll
    Influence of the curvature of the arteries, 50 — Influence of the
    division of the arteries, 50 — Communication of the arteries,
    51 — Course  of the blood in  the veins, 51—Passage  of the
    venous blood across the heart, 53 — Less circulation, 54.

Absorption,  .     .     .     .     .     .     .     .     54 — 67
  Definition, 55 — Proofs  of the existence  of absorption, 55 —
    Mechanism  of absorption, 56 — Imbibition, 56 — Capillarity,
    57 — Endosmosis, 57 — Transport  of the absorbed liquids, 59
    — Apparatus  of  absorption,  59 — Venous absorption, 60 —
    Lymphatic absorption, 60 — Proofs  of the venous absorption,
    60 — Proofs  of the  lymphatic  absorption, 62 — Lymph, 62 —
    Lymphatic vessels, 63— Circumstances influencing absorption,
    63 — Permeability  and vascularity  of the  tissues, 64 — Mass
    of the humors, 65 — Nature of  the absorbed substances, 66.

Exhalation, and the Secretioxs,   ....    67, 68

Transudation, or Sanquineous Effusion,      .     .        68

Exhalation,     .     .     .     .    .     .     .     .68 — 72
  Mechanism of the exhalation, 68 — Circumstances  which influ-
    ence exhalation, 69 — External  and internal exhalations, 70.

Secretions,    .     .     .          .          •    .    72 — 75
  Theory of the  secretions, 72 — Secretory organs, 73 — Humors
    secreted, 75.

Respiration, .          •     •     •     •     •    •    75 — 98
  The vivifying properties of the  air depend upon the  oxygen con-
    tained in it, 77 — Production of carbonic  acid,  78 — Azote,
    79 — Pulmonary transpiration, 80 — Modifications of the blood,
    80 — Theory of respiration, 80  — Source of the carbonic acid,
    81 — Source of the vapor expelled, 83 — Recapitulation, 84 —
    Activity  of the respiration, 84 — Birds, 84 — Mammiferse, 84
    __Inferior animals, 85 — Influence  of animals and vegetables
    upon  the composition of the atmosphere, 85 — Relation  be-
    tween the activity of respiration and the  vivacity of motion, 
Vlll                       CONTENTS.
    86 — Circumstances influencing the extent of the respiration,
    86.

Apparatus of Respiration,  .     •     •     •     •     °'    ^
  Skin, 87 —Special organs, 87 — General characters of the  respi-
    ratory organs, 88 — Differences with  regard  to the mode  of
    respiration,  88 —Gills, 88 — Trachaea,  89 — Lungs, 89 —
    Lungs of Man, 89.

Mechanism of Respiration,  .     •     •     •     •     92 — 96
  Structure of the thorax, 93 — Dilatation of the thorax, 93 — Con-
    traction of the diaphragm, 94 — Motion of expiration, 94 — Ca-
    pacity of the lungs, 95—Frequency of the respirations, 95 —
    Modifications of the respiratory motions, 95.

The Influence  of Respiration  upon  the  other  Functions,
                                                      96 — 98
  Upon the circulation, 96 — Upon the  absorption, 97—Upon the
    pulmonary exhalations, 97.

Animal Heat,    .    .     .     .     .     .     .     98 —105
  Difference in the temperature of animals, 98 — Temperature  of
    the mammiferse and birds, 99— Hibernating animals, 99 — In-
    fluence of age upon the production of heat, 100 — Influence of
    the temperature, 101 — Influence of exercise, etc., 101 — Cause
    of the production of heat, 101 — Influence of the nervous sys-
    tem,  101 — Influence of the  blood, 102 — Influence of the
    respiration, 102 —  Temperature of  the different parts of the
    body, 104 —Power of resisting heat, 104.

Digestion,........105 — 142
  Aliments, 106 — Phenomena depending upon the lack of aliments,
    106—Hunger, 106 — Death from  inanition,  107, — Nature
    and properties of the aliments, 107 — Modification of the ali-
    ments by digestion, 109 — Seat of the digestive process, 109 —
    Digestive apparatus, 110 — Prehension of the aliments, 112 —
    Mouth, 113 — Stoppage of the aliments in the  mouth, 113 — 
CONTENTS.
IX
     Mastication, 113 — Teeth,  113 — Mode of formation, 114 —
     Structure  of the  teeth,  115 — Chemical composition of  the
     teeth, 116 — Development  of  the teeth, 116 — Form of  the
     teeth, 117—First dentition, 118 — Second dentition, 118 —
     Muscles of mastication, 119 — Influence of mastication  upon
     digestion, 120 — Insalivation of the aliments, 120 — Saliva, 120
     — Salivary glands, 121 — Deglutition of the  aliments, 121 —
     Mechanism of deglutition,  124 — Gastric juice, 126 — Delay
     of the food in the stomach, 127 — Formation of the chyme, 128
     — Peristaltic movements of  the stomach, 128 — Duration of the
     digestive process,  129 — Cause of the transformation  of the  ali-
     ments into chyme, 129 — Intestines, 130 — Small intestines,
     131—Fluids contained  in the  small intestines, 131—The
     liver,  132 — Bile, 133 — Pancreatic  juice,  133 — Pancreas,
     133 — Delay  of  the chyme  in  the intestine,  133 — Chyle,
     134—Intestinal gases,  134  — Large  intestine, 134 — Ccecum,
     135 — Colon, 135—Progress  of the remainder of digestion
     in  the  large  intestine,  135 — Theory  of  digestion,  136 —
     Absorption of the chyle,  138 — Chyliferous vessels, 138 —
     Chyle,  139 — Mechanism of the chylous absorption, 140 —
     Uses  of the chyle, 141.

Urinary Secretion,   ......    142 —148
  Urinary apparatus, 142 — Urine, 143 — Source of  the urine, 144
     — Circumstances influencing the activity of the  secretion, 145
     — Gravel, and urinary calculi, 147.

Review,........148—151

Functions of  Relation,    ......       151
  Contractility,  151—Volition, 152 — Sensation, 152 — Instinct,
     152 — Intelligence, 153 — Expression, 153.

Nervous  System,      ......    154 —166
  Nervous tissues, 154—Encephalon, 154 — Parts protecting  the
     encephalon, 155 — Vertebral column,  155 — Dura mater, 155
     — Arachnoid,  156 — Pia mater,  156 — Encephalon,  157 —
                       B 
X
CONTENTS.
    Cerebellum, 160 —Optic lobes, 161 —Spinal marrow, 161 —
    Fibres of  the encephalon, 162 —Nerves,  164 — Ganglionic
    system, 165.

Sensation,  ........    166—174
  Sense of tact, 167 — Sensible and insensible parts, 167 — Influ-
    ence of the nerves upon sensation, 167 — Functions of the spi-
    nal marrow, 169 — Part taken by the brain  in  the perception
    of sensation, 169 — Review,  170 — Nerves  of sensation and
    motion, 171 — Functions of the anterior and posterior roots of
    the spinal nerves, 171 —Cephalic nerves, 172 — Anterior and
    posterior columns of the spinal marrow, 172 — Great sympa-
    thetic nerve, 172 — Special senses, 173.

The Sense of Touch,      .....    174—179
  Structure of the skin, 174 — Dermis, 175 — Rete mucosum, 175
    — Epidermis,  175 — Pores, 176 — Perspiration,   176—Hair,
    176 — Nails,  176 — Seat of the sensation, 176 — Tact and
    touch, 177—Apparatus of touch, 177—Use of this  sense
    178.

The Sense of Taste,.....179—ig]
  Taste of bodies,  179 — Seat of the taste, 179—Structure of  the
    tongue, 179 — Nerves of the tongue, 180.

The Sense of  Smell,      ...         .    181__185
  Odors,  181 — Olfactory  apparatus,  182—Mechanism of  the
    smell, 184 — Nerves of smell, 184 — Uses of the sinuses, 185.

The Sense of  Hearing,   .....    185__196
  Auditory  apparatus, 185—External ear, 185 — Pavilion of  the
    ear, 185 — Auditory duct, 186—Middle  ear, 187 — Cavity,
     187 — Internal ear, 188 —Acoustic nerve, 189 — Mechanism
    of hearing, 189 —Nature of sound, 189 —Use of the  pavilion
    of the ear, 190 — Use of  the auditory duct, 191 —Uses of the
    tympanum, 191 —Transmission  of sounds through the cavity,
     192 — Internal  ear, 192 — Uses  of the air  contained in  the 
CONTENTS.
XI
    cavity, 193—Utility of the cavity, 193 — Eustachian tube, 194
    — Uses of the bones of the ear, 194 — Modifications of the audi-
    tory apparatus,  195.

Light,........196 — 224
  Apparatus of vision,  196 — Globe of the eye, 196 — Iris, 197 —
    Anterior chamber, 197 — Ciliary processes, 198—Crystalline,
    198 —Vitreous humor, 198 —Retina, 198 —Choroid, 198 —
    Optic  nerve,  199 — Ciliary  nerves,  199 — Mechanism  of
    vision, 199—Course of the light in the e,ye, 204 — Uses of the
    aqueous  humor, 204 — Uses  of the pupil, 204 — Uses of the
    crystalline, 205 — Formation  of images upon the retina, 205 —
    Uses of the choroid, 206 — Perfection  of the eye, 206 — Ach-
    romatism,  206 — Aberration of  sphericity,  207 — Presbytia,
    208 —Myopia, 208 — Uses  of the retina, 209 — Muscles of
    the eye, 211—Uses of the nerves  of the eye, 212 — Percep-
    tion of images, 212 — Form of objects, 213—Position of ob-
    jects, 213 — Distance of objects, 214 — Size  of objects, 216
    — Motion  of objects, 216 — Education of the  sense of sight,
    217 — Parts protecting the eye, 219 — Orbit,  219 — Eyebrows,
    220 — Eyelids, 220 — Winking, 221 — Tears,  222 — Lachry-
    mal apparatus, 222 — Apparatus of  vision in animals, 223.

The Intellectual and  Instinctive Faculties,     224 — 232
  Perception,  224 —Memory, 225 — Reasoning, etc., 226 — In-
    stincts, 226 — Relation between the development  of the brain
    and the intellectual  faculties, 226 — Facial  angle, 227 — Sys-
    tem of Doctor Gall, 229.
Contractility, 233 — Muscles, 233 —Muscular contractions, 234
  __Influence of the nerves, 235 — Galvanic experiments, 236
  __Theory of muscular contraction, 237 —Nerves of voluntary
  motion, 239 — Functions of the spinal marrow, 240—Brain,
  240 _ The striated bodies, 240 — Cerebellum, 240 — Respira-
  tory  movements,  241 — Functions of  the medulla  oblongata,
  241 —Involuntary motions, 241 — Laws  of muscular contrac- 
Xll
CONTENTS.
    tion, 241 — Passive organs of motion, 243— Skeleton, 243 —
    Cartilages,  243—Bone,  243 — Development  of  the bones,
    244 — Structure of the bones, 244 —Form, 245 — Articula-
    tion, 245 — Action of the muscles upon the bones, 247 — Force
    of the muscles,  248 — Levers,  250 —Skeleton, 253—Verte-
    bral column, 253—Head, 258 —Cranium,  258 — Face, 260
    — Thorax, 263 — Ribs, 263 — Superior limbs, 263 — Scapula,
    263 — Clavicle, 264—Muscles of the shoulder,  264 — Hu-
    merus, 265 — Ulna and  radius, 265 —Hand, 266 —Carpus,
    266 — Metacarpus, 267 — Phalanges, 267 — Inferior members,
    268 —Iliac bone, 268 —Femur, 269 —Tibia, fibula,  and  pa-
    tella, 269 —Foot, 270 —Tarsus, 270 — Metatarsus, 271 —
    Phalanges, 271 —Muscles of the leg, 271 —Animals  with an
    internal  skeleton, 271 — Standing, 272 — Locomotion, 276 —
    Progression, 277 — Swimming  and flying, 278.

The Voice,........280 — 288
  Mechanism of the production of  sounds, 283 — Acquired voice,
    287 — Singing, 287 — Articulation of sounds, 287.

Functions of Reproduction,    ....     288 — 295
  Creation of animals, 289 — Spontaneous generation, 291 — Nor-
    mal generation,  292 — Generation by slips, 292 — Oviparous
    generation, 292 — Viviparous  generation, 293 — Development
    of the foetus, 294.
Appendix,
303 
ANATOMY AND  PHYSIOLOGY.
             PRELIMINARY  REMARKS.

The object of these lessons is to make known theXssoL.
the most interesting points in the history of animals,
to signalize  those which are useful or injurious to man,
and to show their respective influence  upon industry and
riches in general.
   To do this, the principal phenomena, which charac-
terize their  mode  of existence, must first be exposed,
and  their form  and structure described ;  the  means
indicated, by which  naturalists  distinguish  between
them, and recognise with certainty all these  beings, the
number of which  is so  great  as nearly to terrify the
imagination.   It must be shown,  how  they live, how
they are distributed upon the  different parts of the  sur-
face of  the globe, how they contribute to the well-being
of man, or prove noxious to  his industry, of what riches
they are the source, and of  the means  to which we have
recourse to  procure  them,  or  to  draw from  them  and
appropriate to our own desires  a portion of the products
                  1 
2             ANATOMY AND PHYSIOLOGY.

they  furnish.   In other words,  these  lessons  will  be
devoted  to  the  teaching of comparative anatomy and
physiology.
   The simple announcement  of  the subject on  which I
propose to treat, will  suffice  to  make  its interest and
importance appreciated.  In truth, where is  the man,
whose curiosity has not been  a thousand times  excited
by the sight of the  singular animals, which people  all
around, and which present at every instant of their lives,
phenomena so remarkable, and, often, so incomprehen-
sible ?  Who, when  reflecting upon these phenomena,
and the  actions we  ourselves  execute, does not experi-
ence the desire to scrutinize the  interior  of these com-
plicated  machines, to  know by  what agents, by what
mechanism all these movements are executed ; to exam-
ine the processes, by which  all organized beings assim-
ilate to  their own substance the  foreign  substances  by
which they are nourished ;  and  to inquire the  uses  of
the different organs, of  which the  body is composed.   In
short, every enlightened man must perceive, that  the his-
tory of animals  producing pearls, silk, and wool, which
furnish us our daily  food, or lend us their power, is  of
no mean importance ; and no one can remain indifferent
to  the knowledge of a multitude of other animals, which,
if  less useful, are not less interesting, from the wonder-
ful instinct with which  nature has endowed them.
   It would  then be  useless  to stop here, to  prove that
the study of zoology is a necessary element of educa-
tion, or  to establish by examples  the interest presented
to  us  in  this  branch of human knowledge ; and I shall
therefore hasten  to considerations more worthy to engage
our attention. 
PRELIMINARY REMARKS.
3
           GENERAL  CHARACTERS OF LIVING BEINGS.
   When we cast  our  eyes  over the immense andApn,5S™{J
number of animals, which  populate the surface ^1^™
 c  i     ■,                r      -.                iinals and veg-
of the globe, we are  at first only struck by the etables-
enormous  and  innumerable differences  they present; a
man, a fish, a  spider,  and an oyster, for  example, to a
superficial observer have  nothing in common.   But if
we examine  with  care these different  beings, we  shall
soon be convinced,  that notwithstanding these differences,
there are  a  certain number  of characteristics  possessed
by each of them, and  reproduced without  exception in
all the other anim&is.t  These characteristics are of two
kinds ;  some are furnished us by the material disposition
of the body, and consequently belong to anatomy;'  the
others consist in the phenomena presented by these same
bodies during life, and  they belong to physiology,2 a sci-
ence, which treats  of the actions and  properties of living
bodies.
   The  chief distinction between animals and vegetables,
and  all  the other  bodies of nature,  is life, an  interior
movement, the cause of which is unknown, but  whose
effects are easily perceived.
   All  living  beings,  and these  alone,  possess Nutrition.
the faculty of  duration for a time, and under a particular

  1 Anatomy is that branch of the natural sciences, which treats of the
form, position, structure and qualities of the organs composing the bodies
of living  beings.  This  name is  derived from the  Greek word avaroula,
whose roots (ava within  and rluvtiv to cut) indicate the manner, in which
anatomical studies must  be  made.
 2 From its etymology (cpvai? nature  and Xoyog discourse) the word physi-
ology should signify discourse upon nature or science of nature, but it is
only employed in the signification given above. 
 4            ANATOMY AND PHYSIOLOGY.

 form, by drawing constantly to their composition, appro-
 priating  to  themselves, a  part of the  surrounding sub-
 stances,  and rendering to the exterior world a part of
 their own;  in  other  words, these beings  possess  the
 faculty of  self-nourishment; and,  when  the constant
 addition of  materials, of which they are composed, stops
 without return,  then this  body dies,  and is soon com-
 pletely destroyed ; now, this movement  has always  a
 limited duration, and death  is a necessary consequence
 of life.
   With brute bodies,  such as stones and  minerals, it is
 entirely different.   Once  formed, they exist, so  long as
 a foreign  force does not destroy them ; and during  this
 time, not  necessarily limited, they are not the seat of a
 movement of nutrition: if their volume augments, it is
 by  the simple juxtaposition  of another body similar to
 themselves ; and if they lose a part of their  own  sub-
 stance, it  is by  the  action of a force  from without,  and
 entirely independent of the cause of their  existence.
  The continual movement  of composition and  decom-
 position,   constituting  the  nutritive function  of  which
 living  bodies are the seat, escapes  our senses ; but its
 existence  is revealed  to  us by  numerous facts, very
 readily perceived.
exrsrt0e0nfce0floef   The  desire  constantly  experienced by ani-
movemen"1V  mals to  introduce  into  the  interior  of  their
 bodies foreign  substances, which  may serve them  as
food, already suffices  for  the  presumption,  that  these
 beings  must  continually  incorporate  with  their own
organs materials drawn from  without;  and only by these
 means can  the  increase of volume, so remarkable  in all
 these beings during the first periods of their existence, 
PRELIMINARY REMARKS.
5
be satisfactorily explained.   A newT-born infant weighs
but about six  pounds, and twenty-five years after, when
it  has become adult, its weight  exceeds  an hundred ;
plainly then, at this epoch  of its  life, it has already de-
rived from substances, originally foreign, the  greater part
of the materials of which its organs are composed.  On
the  other hand, the extreme emaciation, which ensues
upon certain  diseases, proves that the  living body may
abandon a portion of the matter, of which it was formed,
and  render to the  external world a part of  its own sub-
stance.
   The experiments of Sanctorius, who, in order to study
the  phenomena of transpiration, passed a great part  of
his life  in a  balance,  prove also that the human  body
constantly experiences diminutions of weight, which the
aliments are destined to repair.
   But a  single example  can scarcely fail  to remove all
doubt of  the  existence of the nutritive movement, even
in the hardest and deepest parts of the  body.  An Eng-
lish  surgeon, Belchier, having by  chance eaten of a hog
raised by a dyer, observed that  the bones of the animal
were red,  and attributing this peculiarity to the fact, that
it  had been  nourished  on coloring matter, he conceived
the  possibility of using similar means  to render visible
the effects of the nutritive function ; and the experiments
undertaken  by him at  that time  resulted  in complete
success, and have  since been satisfactorily repeated by a
great number  of distinguished men.  When animals have
been nourished upon madder for a  certain  time, it  is
always found  that the  bones assume a red color; but if,
after an animal has been thus fed,  the use of the madder
is  suspended,  in  a definite  time the  red matter, which 
g             ANATOMY AND PHYSIOLOGY.
should have been deposited in the substance of these
organs,  is  no  longer found, and  must  therefore  have
been  rejected.   Now these  facts can  only be explained
by  the  continual movement of composition, or decom-
position, to which  the name of nutrition  has  been
given.
juration and   ^  nave alreadj seen, that after a  certain
duration the nutritive movement  is always stopped, and
that all  living  beings, after having existed for a time, the
extreme limit  of which is fixed  for each of them, must
necessarily  perish.  But  this  destruction of the  indi-
vidual does not include the  disappearance of the species;
for another character, common  to all these beings, is the
faculty  of  producing  other beings like themselves, or  in
other words, of perpetuating their race by the phenomena
of generation.
   The  origin  of organic differs completely from  that  of
brute bodies.   The latter have existed from the creation
of the world,  or are  formed by the combination of other
bodies in nothing resembling themselves.   Living bodies,
on the  contrary, always arise  from  a being like them-
selves,  from a parent, to which they are at first united,
and from  which  they are  separated, only  when  their
development is so far  advanced,  that they can maintain
an independent existence.
  structure.   All   living beings have a  common  structure.
 Their  body is  always formed by an union of parts dis-
 similar in  themselves, some of them  being liquid, others
 solid.  It  is  a spongy tissue  composed of lamina, or of
 solid and  very extensible  fibres, which leave  between
 them interstices filled with  fluid ; and this kind of struc- 
                PRELIMINARY REMARKS.               7

ture, which has received the name of organization,  is
one of the essential conditions of their existence.
   To give these bodies form, solid parts are evidently
necessary; and to sustain the  nutritive  movement,  to
make  penetrate into their  intimate  tissue the foreign
bodies destined to be incorporated there, to throw off the
particles ceasing to belong to them, fluid  parts  are  also
requisite.  The latter  should be present in  every  part
in which life is to be  sustained, should  penetrate  into
the substance of the  solids as well as  be  diffused upon
their  surface,  and consequently  these solid  parts must
have a spongy and areolar texture.   It is therefore  im-
possible  to  conceive of the existence of a  movement
similar to the nutritive, without  a mode of structure like
that we  have described;  and observation teaches us  that
this organization is met with in all living beings, animal,
as well as vegetable.   Thus to these has  been given the
name of organic,  in  opposition  to brute beings, which
are styled inorganic bodies.
   Finally, the chemical nature of the materials,  confph0psujon!
of which they are made up, is equally characteristic.
We always find in these  bodies a certain number of  sub-
stances  also to be met with  in  the  inorganic kingdom,
and which here offer  nothing  peculiar ;  water for in-
stance ;  but the products, which  form  the essential  base
of all the solid parts of living bodies,  belong properly  to
the organic kingdom, and present very remarkable prop-
erties.   The number of these  substances is very  con-
siderable,  and  although differing much  in  themselves
they are, for the most part, formed of the same elements
united  in different proportions ; in  general, compounds
of  carbon,  hydrogen  and   oxygen,  or  of   substances 
3               ANATOMY AND PHYSIOLOGY.

resulting from the union of these  three elements with  a
fourth  principle, called azote.1
theecilea™?efrs   We see then,  that there  exist  in nature two
bei°nrgrized   classes  of   bodies;  the  organized   or  living
bodies, and the brute  or unorganized ;  and, by reviewing
what has been said upon  their properties, we  shall  find
that the general  characteristics of the  former, in which
alone  we are interested, consist in  their  mode  of struc-
ture and chemical composition, in  the power they possess
of nutrition and reproduction, in  their origin, and  in the
limited duration of their existence.
               GENERAL CHARACTERS  OF ANIMALS.
            If we  now restrict yet closer the  field of our
observations,  and  confine   ourselves  to   the  study  of
 Chemical
composition
  1 Those substances are called elements, or simple bodies  by chemists,
from which only particles of the same nature can be extracted : for exam-
ple, iron, gold, and sulphur;  at the present day about fifty are recognised,
and by their various combinations all the other bodies in nature are formed.
Carbon, pure and crystalized, constitutes the diamond; while uncrystalized
and mingled with  certain salts, it constitutes  the ordinary charcoal; thus,
to be convinced of the existence of this elementary principle in all organ-
ized bodies, it must be borne in mind, that when warmed by  contact with
air so far as to decompose  them, the residue is charcoal.  Hydrogen, so
called  because it enters into the composition of water, presents itself, when
isolated, under the form of a gas or aeriform fluid of extreme lightness •
combined with carbon, it forms the gas  employed to  give light, and is
obtained by distillation from  coal, oil, etc.  Oxygen is also a gas ;  it forms
about  the fifth part of the atmospheric mass, and  produces by its combina-
tion with a great number of  bodies the phenomena of combustion ; united
with hydrogen it forms water ;  and united to  carbon, the carbonic acid gas,
which is met with in the sparkling wines, beer, etc., and is also disengaged
from burning charcoal.  It is called  oxygen (which means  generator of
acids)  because  it enters into the composition of the greater part of the
acids.   Finally, azote is a gas, which, combined with oxygen, constitutes
the atmosphere. 
PRELIMINARY REMARKS.
9
animals, we shall find that these beings have also other
characteristics, which are common to them, but  not met
with in the  organized bodies of the vegetable kingdom.
And first; the chemical  composition of these beings  is
not the  same ; the  substances which constitute plants,
include little, or  no azote, but have carbon  as a basis;
while in animals azote plays the principal part.1
   In these  latter beings too, life is  manifested ^""v"^
in a much more complicated  form than in veg-bieasn,"vegeta
etables.   To the faculty of  nutrition and  of reproduc-
tion, is added that of executing, under the influence of
an inward volition, movements which tend  to  a deter-
mined end, and that of  feeling, or receiving impressions,
and being conscious of them.   Whence  has arisen  the
name of animated beings, given to animals in opposition
to vegetables, which are called inanimate.
   To  define, then, concisely, the word animal ti^word^anu
we may say, that it is applied to  every body
endowed with the faculty of  nutrition, of feeling, and of
executing spontaneous movements.

       THE FUNCTIONS OF ANIMALS  AND THEIR ORGANS.
   The different  phenomena  by which life  is   organs.
manifested, are always the result  of the action  of some
part of the living body;  and these parts, which  may be
regarded  as  so  many  instruments,  bear the  name of
organs.  Thus an animal can execute movements  only

  1 This difference in the composition of vegetable and animal  substances
is easily proved ; when the latter are burned, the azote they include, com-
bines with a certain quantity of hydrogen, and forms ammonia, which dif-
fuses a peculiar odor when disengaged. Substances not containing azote
do not possess this odor.
                    2 
 10           ANATOMY AND PHYSIOLOGY.

 by the action of certain organs called  muscles, and can
 obtain a knowledge of what  surrounds  it only through
 the intervention of the organs of  the senses.
  Apparatus.    When  several organs concur to  produce  a
 phenomenon, this assemblage of instruments  is known
 by the name of apparatus, and the action of an isolated
 Function,   organ,  or an apparatus  is called the function.
 For  example, we say locomotive  apparatus, to designate
 the  collection of organs which  serve  to transport  the
 animal from  one  place to another, and function of loco-
 motion, to  designate the action of all these parts.
  object of    The functions of the animals have relation to
 different func-                                /»  1      t •
 tions.      two objects :  the preservation of the  individual
 and  the preservation  of  his  race; but  among the first
 an important distinction remains to be established ; some
 serve for the support and increase of the body, others to
 place the animal in relation with the beings which sur-
 round him.  As  for the functions of reproduction, there
 results from  them  the formation of new beings,  similar
 to those from which they originate.
 ofthe'functions'I   The functions or  acts of these beings  may
 then be divided into three great classes, viz. ;  the func-
 tions of nutrition,  the functions of relation, and  the
functions of generation.  Those of nutrition and  gener-
 ation, as we have already seen,  are  common to plants
 and animals; therefore to them has been given the col-
 lective name of functions of the vegetative life ; but those
 of relation exist only in the  latter, and  constitute what
 physiologists call animal life.
   Difference    The manner  in which the  functions  of ani-
 between the
 S£,is fni- mals are  executed, varies  considerably.    In
         some these acts are but few, and life is mani- 
PRELIMINARY REMARKS.
11
fested only by a small number of faculties ; in others, on
the contrary,  the  most varied phenomena  may be ob-
served,  and the  existence  of a  multitude  of faculties,
with which the former are not endowed.  Now, each of
these  phenomena, as we have already seen, is the result
of the action of some part of the body ; and observation,
as well as reason, prove that the  mode  of action of an
organ, or instrument, depends always upon its intimate
nature, structure,  and its other properties.   It follows,
therefore, that the organization of  different animals must
offer as little uniformity as the modes, according to which
these beings fulfil the three orders of functions already
mentioned.
   In animals with the most  limited faculties and simplest
life, the  body  every where presents the  same structure.
The parts composing it are all similar; and, the identity
of  organization  presupposing  an analogous  mode of
action, the  interior of these beings may be compared to
a work-shop, wrhere the workmen  are employed in the
execution of similar labors, and where consequently their
number would  influence the quantity, but not  the nature
of the products.   Each  part of the  body performs the
same function as its neighbor, and the general  life of the
individual is composed only of phenomena,  character-
izing the life of some one of its parts.
   But in proportion as we ascend in the series th?vuaiTabo°r!
of beings, as we approach man, the organization becomes
more complicated ; the body of each animal is composed
of parts, becoming more and more dissimilar,  as well in
form and structure, as in function ; and  the  life of the
individual results from the accumulation of  a  constantly
increasing number of  instruments, possessed of different 
 12            ANATOMY AND PHYSIOLOGY.

 faculties.   It  is  at  first the  same  organ,  which  feels,
 moves,  absorbs from  without nutritive  substances, and
 which continues  the species ; but by degrees the differ-
 ent  functions  are  localized, they  acquire  instruments
 proper to themselves,  and  the  different acts, of which
 they are composed, are executed in their turn by distinct
 organs.   Thus, the  more the life of an animal  is com-
 pounded of different phenomena, and the  more  subtile
 its faculties, the greater is the division of labor in  the
 interior of its  body, and the more complicated its bodily
 structure.
   The principle  which seems to have guided nature in
 the perfection of beings, is, as we see, precisely the one
 which has  had the greatest  influence upon the progress
 of human industry : the division of labor.
 ofCtnisSiawences   There is another consequence  of this  law,
 which merits  our attention,  and which  necessarily pre-
 sents itself to the mind, however little we may meditate
 upon the facts of which we have just spoken.  We have
 seen, that  the higher  an animal stood in  the series of
 beings, the  more various were the  instruments  destined
 to produce  the collection  of the vital phenomena, and
 the more special and limited were the functions  of each
 of these organs.  It results then, that the destruction of
 muSnS.of any part of the body must produce trouble  in
 the economy, in proportion to the perfection of the facul-
 ties  of the animal;  and that those  beings will remain
 so much the  less injured  by mutilations, whose bodily
 structure is less complicated.
   Now  this observation conduces to the explanation  of
several facts,  which, at first, appear incomprehensible,
and finds its confirmation in certain phenomena so extra- 
PRELIMINARY  REMARKS.
13
ordinary, that they would  have been  rejected  as fables,
if they had not been stated  by men,  whose testimony is
indisputable.
   Thus there exist animals, whose bodies may upE0xnp,ehempe^y!
be divided  into  many pieces without arrestingtpe°
the  vital  movement;  on the  contrary,  each  fragment
afterwards  takes on  an unusual development, and soon
constitutes  a new animal, similar  in  form to  that  from
which it springs, quite as perfect in  its  kind,  exercising
the same functions, and living in the  same manner.
         Fig. I.1
                            The singular  beings, called
                         by naturalists fresh water poly-
                         pi,  or  hydrae,  and  which are
                         often found under the water len-
                         tils, present  this queer phenom-
                         enon ;  mutilate  them  as you
                         will, far from killing you mul-
                         tiply  them.   A  naturalist  of
                         Geneva,  of  the last  century,
                         Tremblay, to whom  the know-
ledge of  these curious  facts is due, opened one of these
little animals ; then  he stretched  and cut it  in various
ways, completely chopping  it up,  and,  notwithstanding
this state of extreme division, each of its fragments soon
became a complete animal.
  1 In the figure 1  are represented several hydrae attached to the water
lentils (a); these animals, as will be shown, consist only of a small gela-
tinous tube, open at one of its extremities, and surrounded by a circle of
filaments called tentacula, by the aid of which they introduce aliments into
their digestive cavities.  One of the polypi {b) bears on the sides of its
body two young, which spring from it, and will soon be detached. 
14            ANATOMY AND PHYSIOLOGY.

  To comprehend  this phenomenon, in appearance so
contradictory to all that  the higher order of  animals
teaches us, we must first examine the mode of organiza-
tion  of the polypi,  of which we  have but now spoken.
These animals are too small to be profitably studied with
the naked eye ; but when  seen  through a microscope,
the substance of their body is found  to  be every where
identical; it is a gelatinous mass, in which  no distinct
organ can be perceived,  enclosing  globules  extremely
small.
  Now, as we have already remarked,  identity in the
mode of organization necessarily supposes identity in the
mode of action, of the faculties.   It therefore follows,
that  all  the parts of the body of our polypi,  having the
same structure, must fulfil the  same  functions; each of
them must unite in the same manner with  the rest to
the production of the  phenomena, whose union consti-
tutes life ;  and the loss of one, or several, of  these  parts
does not  therefore  presuppose  the cessation  of any of
these acts.  But  if this be true, if  each portion of the
body of  these animals is  capable of  feeling,  motion,
nutrition, and  the  reproduction of a new being, we see
no reason, why, after being separated from  the rest, it
may not, if placed in favorable  circumstances, continue
to act as  before ;  and why each of these  fragments of
the animal may not only continue  the  performance of
those functions, necessary  for  the support of life, but
also reproduce a new individual, and  perpetuate its race;
phenomena fully proved by the testimony of Tremblay.
uporearTh1118   Let  us now  aPPty  this  same principle to
worms.     beings, whose structure is  less uniform,  and
whose different acts have  already instruments appropri- 
                PRELIMINARY REMARKS.              15

ated  to each of them.  Let us take, for example, the
lumbricus terrestris, or earth worm.
   In this  cylindrical and  slender animal the localization
of the functions  has already been established ;  nutrition
is  composed of a  series  of acts  executed  by different
instruments;  digestion is  effected  in a  cavity,  whose
wTalls possess particular properties;  there exists also a
system  of  canals, serving  to conduct  the  nutritive
materials  to all  parts  of the body, and  an apparatus,
which has become the principal seat of  the faculty of
perceiving impressions, and determining movements;
and  finally,  we  find  instruments  intended  merely  for
locomotion.  Thus we cannot conceive the possibility of
dividing in every  way the bodies  of these worms, as
was done in  the polypi,  without death.   But, if we
examine the disposition of these different sets  of  appa-
ratus, which concur, each in a  different manner, to the
support of life, we  shall find that they extend uniformly
from one  extremity of the body to  the other, and that
each transverse segment of the animal differs  but little,
or not at all, from the others ; it is a constant repetition,
and represents to a certain extent  the entire animal,  for
it includes all the organs, the action of  which  is neces-
sary to  the  vital movement.  We  can then easily con-
ceive the possibility of detaching  a certain number of
these segments from the rest of the body, without causing
either section to  lose any of the vital properties enjoyed
by the entire individual;  and this really takes place.  If
an earth worm  be  cut transversely into two, three, ten,
or twenty pieces, each of its  fragments  may continue to
live as the whole, and to constitute a new individual. 
16            ANATOMY AND PHYSIOLOGY.

 Localization   But by ascending yet higher  in  the  scale of
of the different        J          ° J      .     r  U   ' 1   *   1
fneCtsunPer!onr  animated beings,  the  division of physiological
aniraals-    labor is seen to augment;  the different functions
become the appendages of so  many particular  sets of
apparatus ; each of  the  acts  resulting  is executed  by a
special instrument, and these different sets of  apparatus,
instead of being uniformly distributed through the whole
extent of the body, are lodged in different parts  ; so that
the loss of each portion of  the  body deprives the animal
of some faculty, and produces in the economy a disturb-
ance great in proportion to  the importance of the faculty
in the  support of life.
b/ctoSK!   IR  studying the  different  functions of am-
ine iunc^on0sf mals,  I shall be obliged to indicate the manner
in which  each of them is complicated  and  perfected by
means of this division of labor ; but I shall only  dwell
upon the  most  important facts, and  shall confine myself
to the  examination of the phenomena of life  in beings,
which  in  this relation occupy the summit in the  series of
animals.  In truth, it is, when each of these phenomena
results from  the  action  of  a particular instrument, that
the different acts  of which  the function  is  composed,
may the more easily  be observed, and the effects of  life
be better analyzed ;  consequently  the  most complicated
animals are the best known to  anatomists and physiolo-
gists, and offer to  us the greatest interest.
ORGANIC TISSUES.
  xMateriais    The bodies of these beings include a consid-
forming the                            ~
organs.     erable number of different organs;  but if the
comparative structure of  these  different parts  be exam-
ined, we shall  soon be convinced that  the materials, of 
                PRELIMINARY REMARKS.              17

which they are composed, are far less variable than was
at first supposed.   They are in truth  the  same tissues,
differently combined and  taking upon themselves partic-
ular forms, which  constitute the greater part  of our or-
gans.   The  principal organic  tissues are three,  namely,
the muscular, nervous, and cellular.
   The muscular tissue constitutes what is com-  ^jUSsUe'ar
monly called  the flesh  of animals ; it  is the productive
agent  of all  their movements, and always  consists of
fibres  capable of  contraction.   Sometimes these fibres,
so to speak, are dispersed in the substance of our organs  ;
at others, they are collected  into masses and form mus-
cles ;  but whatever be their arrangement, they are always
distinguished by their  contractile property; and in the
body of man, as well as  of most animals,  they  are met
with in  those situations,  where  there are movements to
be executed.
   The nervous tissue is a soft, usually whitish  Ner™"!tis"
matter,  which  constitutes  the  brain  and nerves, and
is the  seat of the faculty of perception ; when  treating
of the functions  of relation we shall  have occasion to
study its properties and uses.
   Finally, the cellular tissue, so called from its  Ce,,"J"tis"
spongy and areolar  texture, is  of all the materials con-
stituting our organs  the  most  universally  diffused.   In
the simplest  animals it appears to form almost the totality
of the body; and in those  which have, like man,  the
most complicated  structure, this tissue forms a layer more
or less thick  between all the organs, it fills the interstices
these  parts have  between them, and  is also  met with
in their very substance,  where it  serves  to  unite  the
different portions of which they are composed, as on the
                   3 
1 8            ANATOMY AND PHYSIOLOGY.

surface it tends to connect the different apparatus of the
economy ; it is in a measure the link of all  the organs,
and by its different modifications gives birth to the mem-
branes, and  to many other tissues ;  finally, in it the fat is
always deposited,  but the little  sacs containing this  mat-
ter are completely distinct.
  This  tissue is a whitish,  semi-transparent, and  very
elastic substance, composed of filaments and small  lam-
ellae  more or less consistent and irregularly connected,
so as to leave between them grooves, or cellules of  vari-
able  size.   These cellules have but  incomplete walls,
and are separated from  each other only  by a  kind of
spongy lining; thus they communicate together, and afford
a ready passage to the fluids, which traverse them ; lastly,
they are moistened by an aqueous liquor loaded with al-
buminous particles, and known by the name of serosity.
  The communication of these  cellules is easily demon-
strated ;  if  a hole be made in  the  skin  of an animal
recently  killed,  and air  blown  into the  cellular tissue,
this fluid penetrates to all parts of the body, and distends
them.  Butchers do this every day to make their meat
look well ; it has also been practised by some  beggars, to
deform in a  most hideous manner the bodies of unfortu-
nate children, and thus excite  curiosity, or public com-
miseration.
  An example to the point. — A celebrated  surgeon of
the sixteenth century, Fabricius Hildensis, relates, that in
1593 there was exhibited at  Paris an infant from fifteen
to eighteen months of age, whose head was of monstrous
size ;  the parents of the  little unfortunate carried it  from
city to city  as an object  of curiosity,  and attracted a
great  number of spectators ;  but a  magistrate, having 
                PRELIMINARY REMARKS.              ig

suspected some fraud, caused  them to  be  arrested and
put to the torture ;  they then acknowledged, that a hole
had been made in the skin upon  the summit of the head
of the child, and air blown in by means of a tube.   The
operation was repeated every day, and  thus in time the
head of their child had acquired this unusual aspect.   In
our day we  have seen this barbarous practice pursued by
a beggar of Brest.
   The other organic tissues, which concur with  mucous, a-
               °                              brous, bony tis-
the preceding to form the different parts of the sues'etc-
body, are the serous and mucous membranes, the different
varieties of the  fibrous  tissues,  (tendons,  aponeuroses,
etc.) cartilages, bones, etc.; but to all appearance these
are only modifications  of the cellular  tissue.  Finally,
we often see them accidentally developed from the cel-
lular  tissue  ; and in most of these cases the  cause of
their  formation  is known :  thus, whenever the cellular
tissue is submitted  to pressure  and constant friction, it is
transformed to a serous membrane ; when in contact  for
some  time  with an irritating  liquid,  it puts on all  the
characters of the mucous membranes ;  under  the  influ-
ence of traction and mechanical irritation, it gives birth
to fibrous membranes: and  it is to be remarked, that all
these  membranes exist in a normal manner in the  econo-
my, only where those causes act, which  elsewhere would
have  determined  their formation.  The more accurate
studv of these tissues will naturally find its place  Elementary
    J                            j       1     structure of
in the course of this work; we  will only add the tissues-
here,  that all, both the primitive cellular, the muscular,
and the nervous tissues, appear in the  final analysis to be
composed of small globules, visible  only by the  aid of
the microscope, and formed  in  circles of varying disposi-
tion. 
20            ANATOMY AND PHYSIOLOGY.


          THE FUNCTIONS OF  NUTRITION.

   Nothing certain is  known of the manner in which
nutrition is  effected; and  it  is  even probable,  that for
some time yet the mechanism of this internal movement,
the existence of which  has been already demonstrated,
will remain  a  mystery to  physiologists ; but if it  has
been impossible directly to  observe  the labor, by which
the  constituent materials of the  organs  are constantly
renewed, greater success has attended  the  investigation
of the different acts, which prepare, or  accompany  this
curious phenomenon.   We know the  principal agent of
nutrition, and how it is distributed to the different parts
of the body.   The manner,  in  which this agent,  the
blood, can transport to all the organs materials not origi-
nally belonging to it, but which were deposited in a cer-
tain part of  the body, or simply  in contact with certain
parts, has been successfully studied.  It  has  also been
found, that in traversing the organs the blood is deprived
of a portion of its constituent parts, gives birth  to new
liquids, and  changes its nature to such a degree, that it
is no longer suited  to discharge its functions, until it has
been, in some sort, regenerated by the action of  the air;
lastly, it has been seen, that the  nutritious  liquid,  thus
conducing to the  support of the organs, is exhausted,
and must be renewed from foreign matters suitably pre-
pared, in organs especially appointed for this purpose.
   These various phenomena of vegetative,  or  organic
life, give rise to the functions of circulation, absorption,
exhalation,  secretion,  respiration, and digestion ; acts,
which we are now  about to study. 
THE NUTRITIVE FLUIDS.
21
            THE NUTRITIVE FLUIDS,  OR THE BLOOD.
   It has been shown that the nutritive function can take
place only by  the  intervention  of fluid  parts,  and that
every organized body includes liquids as well as solids.
   These  liquids are  merely water, holding in  Liquids con-
            1               J              ~    tained in the
solution or  suspension various  substances, ofbody-
which we shall speak  hereafter.    To their existence, in
the thickness even of the  solid  parts of the body, ani-
mals  owe  in  a great measure  their rounded form, and
from them their organs derive suppleness, and the other
qualities necessary for  the exercise of their  functions.
Thus by desiccation a tendon is  diminished in volume,
loses its suppleness, whiteness, and pearly brilliancy, and
becomes hard, rigid,  semi-transparent,  and  brownish ;
but if  then plunged  into  water,  it  will rapidly absorb
this liquid, and retake in proportion to the absorption the
properties it had lost.
   From this  it might easily be  concluded, that defkcauon.f
the desiccation of an organized body, carried to a certain
degree, must always  interrupt the vital  movement, and
produce death.   And  this  is lalways observed ;  Experiments
r                            l     J            upon the vi-
but  to demonstrate  in  a manner  yet morebrio'etc
evident the  part these liquids play in the animal econo-
my,  I  must state  here the curious  results obtained by
Spallanzani, Buffon, Bauer, and  some other naturalists in
their experiments upon the desiccation of certain micro-
scopic  animalcules.  When the water,  in  which their
bodies  are  soaked, is in  a great measure evaporated,
many of these extremely minute beings  lose  the power
of motion, and cease to afford any sign of life ;  but they
do  not perish  at  once ; they may be preserved in this 
22             ANATOMY AND PHYSIOLOGY.

state  of apparent death for  a very long time,  and to
recall them  completely to  life  only  a  little  water is
requisite ;  this  takes  place  in the  vibrio of wheat,  an
animalcule resembling a small eel, or rather  the ends of
thread, and which lives  in  the grains of blighted wheat.1
   If placed  in  a drop  of  water, and  examined  by the
microscope,  they are at first seen  swimming with viva-
city ;  but when the  liquid has evaporated, they  remain
immovable, and distil  from their  bodies a kind  of var-
nish, which covers them and prevents farther desiccation.
They are  then  completely  deformed,  and  resemble in
nothing  living  beings;  notwithstanding, by  plunging
them into water they soon  retake their forms, and return
perfectly to life, even after having been in this state of
apparent death  for several  months.

  1 Wheat is subject to several maladies, such as carbon, ergot, blight,
rachitis, etc.  The majority of these alterations depend upon the develop-
ment of a species of insect, called vredo, in the substance of the grain ; but
rachitis is owing to the presence of the vibrio, for this disease  may be pro-
duced in ordinary wheat, by inoculating the grain with these  animalcules.
The vibrio is at  the most from two to three lines in length, and  about the
sixth of a line in diameter.
                                                   Fig. 4.
Fig. 2 exhibits one of these animalcules as  seen through a microscope;
and Fig. 3 a grain of wheat  magnified and cut in  two, to display the
vibrios lodged in it, and  the alterations they have caused; lastly, Fig. 4
represents an ear of wheat, which has rachitis; the black points  are the
diseased grains.  What is  said by Buffon with regard to the animalcules of
ergoted wheat, must be applied to  the vibrios of rachitised wheat, for in
the ergot they are not met with. 
THE NUTRITIVE FLUIDS.
23
   Similar  phenomena  have been  observed upon other
microscopic animalcules,  called  by naturalists  Rotifera,
and met with in spouts.   But with  most  animals it is
quite different;  for to them a  real death  is always the
immediate consequence of desiccation to a certain de-
gree.  Fishes afford us  a striking example,  for when
drawn from the  water they soon  perish, and their death
is principally to be attributed  to the desiccation of their
gills.
   The  proportion  of fluids contained  in the  Relative pro-
        x  A                                   portions of the
body of  an animal is much more considerable f^ds and sol~
than we should  have at  first  imagined.   The  tendons,
of which we  were  speaking  above,  contain  half their
weight of  water, and the proportion is much greater in
the other organs.   The body  of a man  contains about
nine tenths of its weight  of fluid;  when a body, weigh-
ing  an  hundred and twenty pounds,  had been  dried in
an  oven seventeen  days,  its  weight  was  found  to be
reduced  to twelve  pounds ;   and  mummies  have been
found not  weighing  more than  seven or eight  pounds.
In  other respects  the proportion of  fluids  and  solids
varies  according to  the  animals,  and individuals; we
may generally say,  that  the relative  proportion of the
former is greater than the latter in youth, and animals of
a simple structure.
   In the animals of an  uniform structure, all thf fl"idL°f
the liquids  of the economy are  similar.  They appear to
be merely water, more or less  loaded with organic parti-
cles ; but in the beings occupying a more elevated rank
in the zoological series, the humors cease to be all of the
same nature, and there  is  one destined  in a special man-
ner to supply the wants of nutrition :  this liquid   Biood.
is the blood. 
24            ANATOMY AND PHYSIOLOGY.

 white biood.   In the majority of inferior  animals the blood
is far from possessing those physical characters, by which
it is recognised in man, and  the  animals nearly allied to
him ;  instead of being red, and  thick, it consists merely
in  an  aqueous  liquid,  sometimes completely colorless,
sometimes slightly tinged with yellow, rose, or lilac.   It
is therefore difficult to be seen ;  and for a long  time it
was supposed, that these beings were completely desti-
tute of it, hence they were called bloodless animals.
  The animals with white  blood, or having the blood  but
slightly tinged, are very numerous : all the insects enter
into this class, and it is an error to consider flies, as hav-
ing red blood in their heads.   When one of these animals
is crushed, we see, it  is true, a reddish liquid exuding,
but this  matter  is  not from the  blood, it arises merely
from  the eyes of  these  little  beings.   Spiders, crabs,
lobsters, and all animals resembling the latter, and which
are classed  by zoologists  as Crustacea,  have  colorless
blood;  also  snails, muscles, oysters,  intestinal  worms,
and all other animals of the  class mollusca,  and  of  the
zoophytes.
 Red wood.    The  blood, on the contrary, is  red in all ani-
mals whose structure approaches man ; such as the mam-
miferae,  birds, reptiles, fishes,  and even  worms  of  the
class, annelida.
th^bioolf.3 of  When  the blood of any  of these beings is
examined by the microscope, it is constantly  found to be
composed  of two distinct  parts ; of  a  yellowish  and
transparent liquid,  to which  has been given  the name of
serum, and of a multitude  of little solid corpuscules, reg-
ular in form, and of a beautiful red color,  which swim in
the fluid  just mentioned,  and  which are  called  the
globules of the blood. 
                THE NUTRITIVE FLUIDS.              25

   In man, and all  other animals of  the  class gll^JI^.or lhe
mammiferae (the dog, horse, ox, for example,) Fi<r. 5.1
the globules of the  blood are circular;  but in  ^%
birds, reptiles, and fishes, they have constantly  7*^
an elliptical form.   These  corpuscules are ex-  ^^
tremely  small.   In  man,  the dog, hare,  and  IjJP
some other mammiferae, their diameter is equal pig, 7.
only to about  the one hundred and fiftieth part
of a  millimetre;  in the  sheep,  horse and ox
they are but one two hundredth of a millimetre ;  in the
goat they seldom exceed the one  three  hundredth of a
millimetre.   In birds the  globules  of  blood are greater
than in the  mammiferae: their  smaller  diameter  is in
general one one hundred and fiftieth of a millimetre, and
their greater diameter varies according  to the animals,
from the one one hundredth to the one seventy fifth of a
millimetre.   In the  class  of  fishes and  reptiles, these
corpuscules are yet greater;  in the  frog, for  example,
their smaller diameter is one  forty fifth of a millimetre,
and  their larger one seventy fifth.
   When these globules are attentively examined tnf giobuies.°f
by a powerful  microscope, they are seen to be composed,
each of two distinct parts, consisting of a  kind of blad-
der,  or membranous sac, in the centre  of which is found
a spheroidal corpuscule.
   Usually this investment is  depressed, and   Fig. 8.s
forms around  the central nucleus, a circular '   ZZ.   >
rim varying in size, so  that  the whole  pre-   Fi9-9
sents  the  aspect of  a  lens.   The exterior t
envelope of the globules is formed of  a kind
  1 Fig. 5, blood of a man ;  Fig. 6, blood of a sheep ;  Fig. 7, blood of a
sparrow.  These globules are magnified one thousand times.
  2 Fig. 8, profile view of the globule in the blood of the frog, magnified
                    4 
26            ANATOMY AND PHYSIOLOGY.

of jelly,  easily divided, and of a  variable red color; to
the presence of  these vesicles the blood owes its color.
The central nucleus of the  globules  exhibits more con-
sistence, and is not colored.
of?h?K?n   In the  ordinary state the blood is  always
liquid, and is composed, as we have  already said, of an
aqueous fluid, holding  solid  globules  in suspension ; but
there are circumstances, in which  its physical properties
are completely changed.  This takes place, for example,
every time that the blood is drawn from the vessels, in
which it is contained in the interior  of the body of the
living animal; when left to itself  it  is transformed in a
few moments to a mass of gelatinous consistence, which
is separated by degrees into two  parts ; one  liquid, yel-
lowish, and transparent, formed by the serum ; the other
more or less solid, completely opaque, and of a red color,
to which has been given the name of clot, or fibrine of
the blood.  The latter is composed principally of globules
more or less changed.
   The blood sometimes loses this property of coagulation.
This singular phenomenon is remarked in animals killed
by a strong electric shock, by lightning, for example, and
by  the action of certain poisons, such as the bite of ven-
omous serpents.  Lastly, at other times the  blood may
resemble its usual mass, but afterwards it separates  into
three parts, the serum, the clot, and a soft grayish layer,
which occupies the surface, and is called the buffy coat.
It is especially in  persons  affected  with  inflammatory
diseases,  such  as  pneumonia,  or inflammation  of  the
lungs, and acute  rheumatism, that  the  blood  is  thus

about seven hundred times.  Fig. 9, front view of the same; the envelope
is torn so as to exhibit the central nucleus. 
THE NUTRITIVE FLUIDS.
27
coated;  and the majority of  physicians agree  in regard-
ing  it as a certain sign of the  existence of an  internal
inflammation ;  but recent observations prove, that the
formation  of the coat  may  depend  upon  circumstances
entirely  different, and which in themselves  have  no im-
portance, such  as the size of the opening in the vein, the
form of  the vessel in which the blood is received, etc.
   Chemistry teaches us, that the blood  contains ^jgj,,,
the  greater part of the substances, which  enter  into the
composition of the different  organs of the  body which it
is destined to nourish.   In man, to the hundred parts of
blood there are  met with seventy-eight parts of  water,
six  to seven parts of albumen,1 fourteen to fifteen parts
of fibrine and coloring matter,2 some  thousandths of fatty
matters, soda,  salts,3 finally traces of the peroxide of iron.
Under ordinary circumstances, those  substances  cannot
be discovered in the  blood, which are found in the differ-
ent humors formed from it in the interior of the body ; but
if the action of those organs, upon which the  secretion of
those humors depends, be arrested, then we find  the mat-
ters in question in the blood.   It must then be concluded,
that they always  exist, but in  too  small  quantity to  be
appreciated by our means of analysis, and that the organs

   1 Albumen is a matter, which enters into the composition of the majority
of the organic tissues of animals, and which forms almost  of itself alone,
the white  of the egg.  It dissolves in water, but solidifies and becomes in-
soluble by heat.  From  the existence of the  albumen in  the blood,  the
sugar refiners employ this liquid to clarify their syrup, as might be done by
the white  of eggs.
   1 Fibrine forms  the basis of muscular flesh.  To extract it  from the
blood this liquid must be beaten with rods before it coagulates; the fibrine
attaches itself to the twigs, in the form  of white, very elastic filaments.
   3 Chlorides of sodium and of potassium, phosphates, sulphates and alka«
line carbonates, and carbonates of lime, magnesia and iron. 
28            ANATOMY AND PHYSIOLOGY.
we have mentioned do not form them, but separate them
from the blood  as  they are  developed.   Wherefore the
blood may reasonably be  regarded, as containing all the
materials necessary for  the formation, both  of the  solid
and  fluid parts  of  the  body, and  as well meriting the
name, conferred upon it  by some authors, of flowing flesh.
  proportions   The relative proportions, in which the liquid
of the serum                r  l
and giotuies.  an(j SQy^ partS) or tne globules and serum enter
into the composition  of the  blood, vary in different ani-
mals ;  and as we shall soon see, there exists a remarkable
relation between the quantity of the globules,  and the
heat developed  by these  beings.   Birds are of all ani-
mals those, whose blood is richest in globules, and those
also whose temperature is the  most elevated ;  the glo-
bules constitute  in general fourteen or fifteen hundredths
of the  total  weight  of this  liquid.   The blood of the
mammiferae contains rather less, and in this connection a
difference exists among  these animals ; in the carnivorous
and omnivorous  classes  the proportional quantity  of glo-
bules seems to  be  greater than  in  the herbivorous; in
man, the  dog,  and cat, they constitute from twelve to
thirteen hundredths of  the total weight  of the blood;
while in the horse, sheep, calf, and hare, they form but
seven or nine hundredths.  But the number of  herbivo-
rous and carnivorous,  whose blood has been examined, is
not so great that this  result can be  regarded as a physio-
logical law.   Lastly, in  reptiles and fishes, which are
styled  animals with cold  blood, on  account of the little
heat they develope, the relative quantity of the  globules
is much less, and hardly  exceeds five or six hundredths
of the  total weight of the blood.
  In  other respects, the  proportions of  the solid  and 
                THE NUTRITIVE FLUIDS.              29

liquid elements vary in individuals of the same  species,
and  different  circumstances  may occasion  modifications
in the  blood of the same  animal.   The quantity of glo-
bules is greater, and that  of the water less, in man than
in woman, and in the blood of individuals of a sanguine
temperament, than in those of a lymphatic.
   It would appear, that there exists an intimate ^SSL?f the
relation between these globules, and the vital energy;
where  the phenomena of  life are exhibited with the most
intensity, there it is found, that the blood is richest in
globules, and  vice versa.  It is even to the  presence of
these particles, that this liquid owes, in a great measure,
the  faculty of exciting and  sustaining  the vital move-
ment.   The following experiment is- a proof of it.
   When an animal is  bled  to  syncope, and the he^hagf.
flow of blood not arrested, in a few moments all muscular
motion ceases, respiration is arrested, and  life is no longer
manifested by any exterior sign.  If the animal be left
in this state, the reality soon succeeds to the appearance,
and death speedily arrives.   But if blood, similar to that
which it had lost, be injected into its veins ;  this  Transfusion.
apparently dead body is seen with astonishment to return
to life;  in proportion  as  new quantities of blood are in-
troduced into its vessels, it gradually revives, and  soon
breathes freely, moves with  facility, resumes its accus-
tomed  habits,  and is completely reestablished.
   This operation, known by the  name of transfusion, is
surely  one  of the  most remarkable ever  made; and
proves, better than all that can be said, the  importance
of the  action of the globules upon the living organs; for
if serum  destitute  of globules  be employed,  no  more
effect is produced than if cold water had been used, and 
30            ANATOMY AND PHYSIOLOGY.

death is notwithstanding an inevitable  consequence of
the hemorrhage.
  But it is not as a simple physiological experiment, that
transfusion has become  celebrated; it is  as a curative
means, that attention has been directed to it, and its his-
tory will  furnish an example of the  grave errors, into
which men fall, when  they  would  apply to practice an
incomplete science, a danger, which has caused it  to be
said with some truth, that " ignorance is less dangerous
than half knowledge."
  About the middle of the seventeenth century, physi-
cians  attributed almost all diseases to  alterations in the
blood ; and they supposed  that by changing  this  they
would be able to heal all  ills ; thus, without having pre-
viously studied the conditions necessary for the  success
of the operation of transfusion,  they hastened  to put it
in operation ;  and  Wren in England, Major in Germany,
Druis and Emmert at Paris, and several other physicians,
caused to  be thrown  into  the  veins  of their patients
sometimes  blood  from  a  healthy  man,  and sometimes
from a calf.
  Some of these attempts were  not injurious, but others
occasioned the most unfortunate accidents, even death;
and by an act  of the parliament  of Paris, passed in
1668, an end was  happily put to these murderous exper-
iments.
a2£ZS£   If' instead of Prematurely applying the ope-
giobmes.    ration of  transfusion to the art of healing, the
question had  been studied in its different aspects, as has
been  done of late years,  these  misfortunes would  have
been avoided, and  a means, which in some cases is really
useful, would not  have  been generally proscribed.  The 
                 THE NUTRITIVE FLUIDS.             gj

experiments published at London by Blundel, and at Ge-
neva by Dumas  and Prevost prove, that  by proceeding
in a certain manner the operation is  always successful,
but if an opposite course be followed, it leads to an un-
fortunate result.   Thus the first condition  of  the success
of transfusion, is the injection of blood flowing from an
animal of the  same species with that,  upon which  the
operation is performed.   If blood be introduced, differing
from that of the animal in the volume of its  globules,
and not in form; if, for example, the blood of a cow, or
sheep, be thrown into the veins of a cat, or hare, the lat-
ter revives  but imperfectly, and soon dies.  Finally, if
blood with  circular  globules be transfused into animals,
whose  blood contains elliptical globules,  or  vice versa,
death takes place in a short time, and is accompanied by
nervous symptoms similar to those produced by the most
violent poisons.
   The result then of transfusion, as it was prac-  Application.
tised in the  seventeenth  century, is  not to be wondered
at; for it was inferred, that because the blood of a sheep
could be introduced into the vessels of another sheep, it
might also be injected into the veins of  a man.   But on
the other hand, we see, that by employing  only the blood
of an animal of the same species with that on which we
operate, it would not be  impossible to derive a successful
result from transfusion in the practice of medicine ;  and
in England  it has been employed with marked success in
several  cases,  where death was  imminent.   Notwith-
standing, recourse can only be had  to this operation in
extreme cases, for it is always very delicate ;  and  if a
certain  quantity of air be introduced into the veins along
with the  blood, a thing which may easily happen, the 
32            ANATOMY AND PHYSIOLOGY.

death of the patient is  instantaneous;  for this gas, hav-
ing arrived at the  cavities of the heart, is warmed, ex-
pands, and prevents their contraction, a mechanical ob-
stacle, which stops the circulation.
 influence of   The  influence of  the blood upon nutrition is
the blood upon                                -   T\ru    U
nutrition.    equally easy  to  be  demonstrated.   When  the
quantity of this  liquid  received by any organ is dimin-
ished by mechanical means in a marked and  permanent
manner, the latter  is seen to diminish in size, and often
to contract, and  be reduced almost to nothing.   On the
other hand,  the  greater the  functions  of  any part,  the
more  blood it receives, and the more  it increases in size.
Every one knows, that muscular exercise tends to devel-
ope the parts which are the seat of it;  as in dancers, for
example, the muscles of the leg, and of the calf espe-
cially, acquire a remarkable  size, while in blacksmiths,
and other men, who execute  rough labor with their arms,
the muscles of  the superior  limbs become more  fleshy
than  the  other parts.   Now the  muscles  receive more
blood when they contract than when in repose, and by
this afflux of blood  the nutritive labor, of which they are
the seat, is rendered active, and  their volume increases.
  influence of  From  the  experiments we  have related, it
the organs upon                x                          '
the biood.   may foe seen that the  blood serves not only to
repair the losses in the  living organs, and  nourish  them,
but also to produce in certain parts an excitement, with-
out which life could not be  maintained.  Now by thus
acting upon the  organs, with which it is in contact, this
liquid in  its  turn  experiences  from them modifications,
ven™.riwoaod! and soon  loses its vivifying qualities.  The
blood, on arriving in the different parts of the body, is of
a red vermilion  color;  while,  after  having traversed 
CIRCULATION.
33
them, it presents a dark tint of blackish red, and in this
state does not possess the faculty of sustaining life in the
organs to which it is supplied.  But blood thus vitiated,
or which has at least been used, retakes by the action of
the air its primitive properties, and then becomes adapted
to excite the vital movement.
   The  function, by the aid  of  which  this  important
change is effected, is that  of respiration, with which we
shall soon be occupied.  Blood, which has been submit-
ted to the action of the air, and which is proper for the
support of life, is called arterial blood; that,  which has
already acted upon  the  organs, and  which cannot  con-
tinue to excite the vital movement, is called venous blood;
it contains in general fewer globules than the  arterial,
and coagulates less promptly, but  its chief distinguishing
features are, its black color, and its  mode of action  on
the living tissues.
           CIRCULATION OF THE BLOOD.

  From what has been said of the part taken  Necessity of
                                   1           a circulatory
by the nutritive liquids in the animal  economy,  movemem-
and  of the  influence  exercised by respiration upon the
physiological properties of these liquids, it is evident that
they must be the seat of a continual movement.
  Since it is the blood, which distributes to all  parts of
the body the materials necessary for their nutrition, and
since this liquid is also the mean,  by which the particles
eliminated from the substance of  the tissues are thrown
out,  it cannot  remain in repose,  and must necessarily
                   5 
34            ANATOMY AND PHYSIOLOGY.

traverse constantly all the organs.  But in  the majority
of animals these are not the sole conditions of existence,
which render the motion  of  the blood  indispensable to
the support of life ; when the air does not penetrate into
the substance of all the tissues, (as is the case in insects)
but acts only by the intervention of  the exterior surface
of the body, or of a special organ of respiration (as  the
lungs), it  is  equally easy  to  see, that the  blood, which
has already traversed the  tissues, must pass to the respi-
ratory apparatus to  be submitted to the vivifying influ-
ence  of  the  air, before  returning  anew to these same
tissues.
   Now this actually takes place, and this movement con-
stitutes what is called by physiologists the Circulation of
the Blood.
theAEuuto£f In  animals with  the simplest structure,  the
nutritive  liquid is  diffused uniformly in all parts of  the
body ; it fills  the  spaces which the various  organs, or
their constituting lamellae, leave between  them; lastly,
it presents but slow and irregular  motions.   But when
we examine beings more nearly allied  to man, the blood
is seen to  move in a constant direction, and there exists a
particular organ for  the purpose  of impressing  upon it
   Heart,   this motion.  This organ, called the  Heart, is a
kind of  contractile pocket, which receives  this  liquid  in
its interior, and contracting upon itself, drives it in a de-
 terminate course.
   By ascending in the scale of beings we see also, that
 the blood soon ceases to circulate in  simple  spaces, but
 moves in a system of  canals, having walls  proper to
 themselves, and which are independent of the neighbor-
 ing parts.  These canals bear the name of blood vessels, 
CIRCULATION.
35
and, with the heart, constitute the apparatus of the circu-
lation.
   The currents, of which we have just spoken,   vessels.
are seen in some animals, which have not well-formed
blood vessels, and  in the incubating egg they are  seen
before the cavities containing the blood  have  acquired
distinct walls.   These currents  may even  be regarded as
the determining cause of the formation of these vessels,
for whenever,  in consequence  of certain diseases, such
as fistula, a part of the body is frequently traversed  by
any liquid,  the  accidental  passage  thus  worn is soon
clothed with a membrane, and  transformed into a canal,
having proper walls and independent of  the neighboring
parts.
   However, the vascular system is composed of Artveier?sand
two orders of vessels ;  of centrifugal canals, which carry
the  blood from the heart to the interior of  all parts of
the  body, and  of centripetal canals, which  return this
liquid from these organs to  the heart — the former are
called arteries, the latter veins.
   From the functions of these  vessels  we can judge
what ought to be their general arrangement. The arteries,
having to distribute to all parts of the body the blood issu-
ing  from the heart, must necessarily be  subdivided, and
ramified in proportion to their distance from this organ.
The veins, on the contrary,  must present an  inverse dis-
position ;  they must be,  at first,  very   numerous, and
gradually unite so as to terminate at the heart  by one or
two great trunks.  (Fig. 13.)  The arteries,  as we see,
may be compared  to  the branches of a  tree, and the
veins to its roots; but they differ in one very  important
respect; for in place of being separated from each other, 
36            ANATOMY AND PHYSIOLOGY.

as the branches and  the roots of plants, the arteries and
veins must be continuous, so as  to form but a single sys-
tem of canals, and  the blood must pass from one to the
other by traversing the  substance of the organs.  This
  cvaepsseisry  is actually observed ; and the name of capillary
vessels is bestowed upon the narrow canals which unite
these two orders of ducts, and which may be considered as
being at the same time  the  termination of the arteries,
and the origin of the veins.
  The arteries and  veins, thus communicating through
one of their extremities by the intervention of the capil-
lary vessels, are united at  the opposite extremity by the
cavities of the heart; whence it results, that the vascular
apparatus forms a complete circle,  in which  the  blood
moves, to return unceasingly to its first point of depart-
ure, and from the  nature of this movement it is called
the circulation.
thSSon!   This phenomenon was unknown  to the  an-
cients ;  the majority of the authors of antiquity supposed
that blood  only existed  in the veins,  and thought, that
during life, as well  as after death,  the  arteries  were
empty, or contained merely air.   But about the middle of
the second  century of  the christian era, Galen proved by
delicate experiments made upon  living animals the pres-
ence of this  liquid in the arteries, and thus  paved  the
way to the discovery of the circulation.   This celebrated
man rendered to science many other  important services,
and she would certainly have reaped  yet greater advan-
tage from his labors,  if by a fortuitous event posterity
had not  been deprived of a great  part of his writings :
he left five hundred manuscript rolls, containing materials
for about eighty of our octavo volumes, and they were con- 
CIRCULATION.
37
sidered so precious, that for their better preservation they
were  deposited in  the temple of Peace  at Rome ; but
this very precaution was the means of their destruction,
for they were consumed  together with the edifice in the
reign  of the emperor Commodus.1
   In  the  sixteenth century some new light was thrown
upon this important point in physiology.   Michael Servet,
known as a theologian  rather  than  physician,  and  cele-
brated for having been burned  as a heretic in a reformed
city, and  by the instigation  of the reformer Calvin,2 has
pointed  out  in one  of his works, the  direction  of the
course of  the  blood in the pulmonary veins ; but the dis-

  1 Galen, one of the greatest physicians of antiquity, was born at Perga-
mos, a city of Asia Minor, in the year 131, the fifteenth of Adrian's reign ;
he studied sometime at Alexandria, whose  medical and  scientific schools
were then in a most flourishing condition,  and at the age of 34 years  he
went to Rome, where he acquired by his public lectures a great celebrity,
and where he excited among  the other physicians so great jealousy, that
he was soon  obliged to quit the city, and return to Pergamos.  At this
moment an epidemic broke out in Italy, and his enemies profited by this
circumstance, to accuse him of cowardice.  He had, notwithstanding, the
real advantage of enjoying during his life-time all the  glory his genius
could assure to him, and his high reputation remained inviolate for a long
succession of ages.  At the age of 38 years  we find him called to Aquilea,
by Marcus Aurelius, to combat a violent epidemic raging in the army of
Germany, and the same prince afterwards put under his charge Commodus,
his son, whose health was  very delicate.  Galen, however, did not delay
returning to his natal city, where he died in the year 200, at the age of 69.
He was one of the profoundest anatomists and physiologists of antiquity;
in this respect he may be compared to Aristotle; and as a physician, he
ranks next to Hippocrates.  During a long period his reputation has been
yet greater, and in the middle ages his writings were, so to speak, the sole
guide of physicians.
  2 The unhappy Servet,  driven by the intrigues  of Calvin to fly from
France, passed through Geneva where his implacable enemy was in power;
he was arrested for his religious writings, and Calvin procured his condem-
nation to the stake.  Servet was burnt alive the 27th October, 1553. 
38            ANATOMY AND PHYSIOLOGY.

covery of the circulation actually dates from  the com-
mencement of the seventeenth century, and the glory of
it is due to Harvey, professor of anatomy at London and
physician  of the unfortunate king  Charles  I.  In  the
lectures given by him in 1619, he pointed out the me-
chanism  of this  function ; his ideas were  immediately
attacked on all sides with virulence, and when his envi-
ous contemporaries could no  longer throw doubt upon
the truth of his great discovery, they attempted to wrest
the glory of it from him, by pretending that it  had been
known for a long time ;  they allowed Harvey only the
merit of having  propagated the knowledge of it, or, as
they said,  of having circulated the circulation  of  the
blood: but posterity has rendered  to  him full justice,
and his name will always be cited as one of the greatest
of physiologists.
exTsrte°nfceoftofe   The  existence  of  the  circulatory  movement
tioen.cin    of the  blood is easily  demonstrated.   If  we
examine  by  the  microscope  a transparent part  of  the
body in a  living animal, the membrane which unites the
claws of  the  hind foot of the  frog,  for instance, we see
distinctly  sanguineous currents traversing  innumerable
capillary  vessels,  and  continuing into other  canals,  yet
larger.  The direction of these currents is equally easy
to show; if an artery be compressed, so as to interrupt
the course of the blood, this liquid is seen to accumulate
in that portion of the vessel situated towards the heart,
and to distend its walls, while beyond  the compressed
point, the  artery is  in a short time more or  less com-
pletely emptied ;  it is then evident, that the  blood tra-
verses these canals from the heart  to the various parts of
the body.  Now when the same experiment  is  made 
CIRCULATION.
39
upon a vein, the  contrary effect is produced;  the blood
accumulates beyond  the compressed point, and does not
flow in the portion comprised between this point and the
heart;  for if the vessel be opened  above and below this
same point, the  blood forcibly escapes from the  lower,
and not at all  from the upper, opening.  The  common
manner of bleeding  in the  arm also shows, that in the
venous system the blood follows an opposite direction to
what we have  seen in the arteries, and returns from the
various parts of the  body to the heart; to swell  up the
vein, and facilitate the flow  of blood, the vessel is com-
pressed by means of a ligature immediately above the
point where the opening is made.
   In all those animals, in which respiration  is ies^dreuW?onnd
made by a special organ, such as the lungs, the sanguine-
ous vessels ramify not merely in the tissues they are to
nourish, but also  in  the organ in which the  blood must
be  submitted  to the action  of the air ; and  this liquid
traverses two  kinds of capillary vessels ; one serving for
nutrition, the other for respiration ;  the circulation carried
on in the respiratory apparatus is called the less circulation,
and that of the rest of the body the greater circulation.
   In other respects, the course followed  by the th^oou011 of
blood,  and the structure  of  the  circulatory  apparatus,
vary much  in  the  different  classes of animals ; thus, in
crabs and  lobsters  the  heart consists only  of a  single
contractile pocket, which sends the blood to all parts of
the body, whence this liquid passes into the venous sys-
tem to be returned  to the heart by traversing  the organ
of respiration.   In  snails,  oysters,  etc., the an£Xiicues°ca!
blood follows the same course, but there  is a division of
labor in the functions of the heart; this organ presents 
 40            ANATOMY AND PHYSIOLOGY.

 a more complicated structure, and is composed of a cavity
 called a ventricle, which serves to put  the  blood in mo-
 tion, and of one  or two  pockets, called auricles, which
 receive this liquid from  the veins, and serve as a reservoir
 to supply the ventricle.
  Fishes.    In fishes,  the structure of the circulatory ap-
 paratus is nearly the same, with this difference, that the
 heart, in the place of being situated at the  passage  of
 the arterial blood, belongs to that portion of  the  circula-
 tory circle,  traversed by the venous blood  passing from
 the various  parts of the body to the organ of  respiration,
 which is expressed  by saying, that  these animals have a
pulmonary  heart; while in  those spoken of  above the
 heart is aortic, or belonging to  the great artery of the
 body, which is called the  aorta.
   In all these animals,  the  entire mass of venous blood
 traverses the organ  of respiration, and is transformed into
  Eeptiiea.  arterial blood  before returning to the different
 parts of the body;  the  vessels  of the greater circulation
 pass entirely into those  of the less, and the circulation is
 double ; but in frogs, serpents, and other  reptiles, it  is
 more simple ; the less circulation is but a fraction of the
 greater,  and  the venous  blood  is  not entirely changed
 into arterial, but  mingles partly with the blood  coming
 from the respiratory apparatus, and  thus returns to the
 organs.
  anHirdT    Finally, in  man and all the  other animals
 called by naturalists mammiferous,  as well as in birds,
 the circulatory apparatus is  yet more complicated.  The
 heart presents two  auricles, as  well as  two  ventricles,
 and  is divided into  two distinct  parts;  the portion situ-
 ated on the left side, composed of an auricle  and ventri- 
CIRCULATION.
41
cle, corresponds to the aortic heart of snails and lobsters,
and serves to send the arterial  blood to all  parts of the
body ; while  the  right  half of the heart, which is com-
posed in the same manner, sends the blood to the lungs,
and  consequently performs the  same  duty as the pul-
monary heart of fishes.
   The  blood, arriving  from  the different parts of the
body by the venous  system, first enters the right auricle ;
thence  passes into  the  ventricle of the same side, from
which it  is sent  to the lungs  by the pulmonary artery ;
after having traversed the  respiratory organ it returns  to
the heart by the pulmonary veins, which open into the
left  auricle ;  lastly, from the left  auricle the blood de-
scends  to the left ventricle, and this latter cavity sends it
to the  arteries,  by them to  be  conveyed to all parts of
the body, whence it returns,  as we have already  seen,
to the right auricle  of the heart.
   Thus we  see  then, that in animals the blood  passing
through  the  circle  of  circulation, twice  traverses the
heart:  in the state  of venous blood  on the  right, and as
arterial on the left  side of this organ ;  notwithstanding,
each  circulation is in itself complete, for the pulmonary
cavities and the aortic cavities of the heart  do not open
into each other, and the entire venous blood must traverse
the respiratory apparatus to  be transformed  into arterial
blood.1
             APPARATUS OF CIRCULATION IN MAN.
   In man, which we shall take as an example  Heart.
for the illustration of  the apparatus of  circulation,  the

   1 Before birth it is quite different, as will be seen when treating of re-
production.
                     6 
42
ANATOMY AND PHYSIOLOGY.
heart is lodged  in  the cavity of the chest, called by ana-
tomists the thorax;  its  inferior extremity is  directed a
little to the left and  forward, and  its superior extremity,
whence arise all the vessels communicating with its inte-
rior, is fixed to  the neighboring parts nearly in the me-
dian  line of the body.   In the remainder of its extent,
the  heart  is completely free,  and  it  is enveloped  by a
kind of double  membranous sac,  the  pericardium; the
inner surface of which is in contact with itself, perfectly
smooth, and constantly  moistened  by an aqueous liquid,
which serves to render  the motions of this  organ  more
easy.
                                    The  general  form of
                                 the heart is a cone, or
                                 irregular reversed  pyra-
                                e mid ; its volume is about
                                 equal to the  fist, and its
                                 substance almost entire-
                                 ly fleshy ; it is a hollow
                                 muscle,  the interior of
                                 which is divided  by a
                                 large vertical partition
                                 (Fig. 11,  c) into two
                                 halves,  each  containing
                dh h     a        two cavities, a ventricle
 and an auricle,  (a, e, and b, d.)
  1 a, Portion of the heart occupied by the left ventricle, —b, right ventri-
cle, — c, right auricle.  The left auricle is seen above  the ventricle of the
same side, — d, vena cava inferior, — e, subclavian and jugular veins, ter-
minating in the superior vena cava, —/ and g, carotid and subclavian ar-
teries, originating from the arch of the aorta, — ^descending aorta, — t,
trachea,—p, lungs. 
                       CIRCULATION.                    43

   The two ventricles of the heart         „•   n,
                                          tig. 11.
occupy  its inferior  portion, and     i    k   h    k
their walls are  endowed with a     \  L^Jk   /
strength much greater than those     -dt^i^w/?''?*
of  the  auricles, the   utility  of  ^'"'■^^n^^fip
which circumstance  is evident:  .......^^^^k\^^P?-----"-'-f
for the auricles have only to send  {—-/}$     Jf /
the  blood  into  the  ventricles,       -^^Pi^^■"*"•
while  these latter cavities must   .■■■''    X/yffl
send it  to a much more conside-          /  ^^/
rable distance, either to the lungs,         c    W
or to the other parts of the body.  The left ventricle is
also much  stronger  than the  right, and  the comparative
extent of  the  passage,  that the  contractions  of these
cavities  must cause  the blood to traverse, also  explains
the cause of this difference ; for the  right ventricle sends
this liquid only  to the lungs, situated but a short distance
from the heart, and the left ventricle drives it to the most
remote parts of  the  body.
   The vessels, which are to transport the arterial   Aorta.
blood  to all the  organs, spring from the left ventricle  (a)
of the heart by  a single trunk, called the aorta.  (See  fig.
10 and 11, h.)  This great artery ascends to the base of
the  neck,  then  curves  downward,  passes  behind   the
heart,  and descends vertically  in  front  of the  spine  to
the inferior part of the abdomen.   In  its course a great
many  branches are given off, the principal  of which are,
  1 Section of the heart to display its cavities. — a, left ventricle, — b, right
ventricle, — c, fleshy septum dividing these two cavities, — d, right auricle,
— e, left auricle,—/, valve which separates this cavity from the left ven-
tricle, — g, valve separating the right auricle and ventricle, — h, aorta, —
h\ the same after its passage behind the heart, — i, i, venas cavse, — k,  pul-
monary arteries, — /, pulmonary veins. 
44            ANATOMY AND PHYSIOLOGY.

the two carotid arteries, which ascend on  the side of the
neck, and distribute the blood to the head ;  the two ar-
teries of the superior limbs, which  take successively the
names of subclavian, axillary, and brachial arteries accor-
ding as they pass under the clavicle, traverse the axilla,
or descend along the arm ;  the cceliac artery, which goes
to the stomach, liver, and spleen ; the mesenteric arteries,
ramifying in  the  intestines ;  the renal  arteries,  pene-
trating the kidneys ; and the iliac arteries, which termi-
nate the aorta, and convey the  blood  to the inferior limbs.
   veins.     The veins, which receive the blood thus trans-
mitted to all  parts of the body,  follow nearly the same
course as the arteries ; but they  are larger, more numer-
ous,  and in general more  superficially situated.  A great
number  of these  vessels  lie directly beneath  the skin,
others accompany the arteries, and at last they all unite
to form two great trunks, which  open into the right auri-
cle of the heart, and which  have received the names of
vena cava superior, and inferior. (Fig. 10, d, e, Fig. 11, i.)
 venapona.   The veins of the intestines present in their
course a remarkable peculiarity: the common  trunk,
formed  by their union, penetrates into the substance of
the liver, and  there ramifies; so that the  blood of these
organs does not return to the heart, till after it has circu-
lated in a particular system of  capillary vessels contained
in the liver, and  giving birth to canals, which open into
the vena cava inferior.  This portion of the venous appa-
ratus is called the  system of the vena  porta.
  Paurt'e1rynary   Tfle vessel> which  conveys  the venous blood
from the heart to the lungs, is called the pulmonary ar-
tery (Fig. 10 and  11, Ac); it arises from the  superior and
left side of the right ventricle,  ascends by the side of the 
                     CIRCULATION.                   45

aorta, and soon divides into two  branches, which sepa-
rate almost transversely from each other, and  ramify in
the lungs ; that of the right side passes  behind the aorta
and the vena cava superior; that of the left side passes
in front and  above the arch of the aorta.   The former
subdivides into three branches before  penetrating into
the substance of  the  lungs; the second  into two;  they
both ramify upon the walls  of the pulmonary cellules.
   The pulmonary veins originate in  the sub-  Va\™?™y
stance of the  lungs, from the  minute capillary divisions
of the arteries of the same name,  and unite in twigs and
branches, which  follow the same course with the latter
vessels ;  they  finally form  four trunks,  two from  each
lung, passing to the left auricle of the  heart,  to which
they transmit the blood, arterialized  by its contact  with
the air in the  interior of the respiratory organ.
   The arteries and veins are lined interiorly by structure of
                                         J  J the blooil ves-
a thin, smooth membrane, continuous with  thatsels>
lining the cavities of the heart, and analogous with those
known to anatomists as serous.   In the arteries, this  in-
ternal coat is surrounded by a  thick sheath, yellow and
very elastic, composed of fibres of a peculiar nature, cir-
cularly disposed ; and the whole is contained in  a  third
tunic, formed  by thick close cellular tissue.  In the veins,
no distinct cellular coat can be discovered, and the inter-
nal membrane is  only surrounded  by a thin layer of lon-
gitudinal, loose, and  extensible fibres.  There must  be
then a very great difference in the physical properties of
these two orders  of vessels.   The veins have thin flaccid
walls, which sink when they are not distended by blood,
and which quickly cicatrise, when  divided.  The  arte-
ries, on the contrary, have walls much thicker, and pre- 
46            ANATOMY AND PHYSIOLOGY.
serve their calibre even when empty, as always happens
after death.1  Lastly, when these latter vessels are open-
ed, the edges of the wound tend to separate, on account
of the elasticity of the fibres of the median  tunic, and
cicatrization is  never completely effected, except by the
obliteration of the artery at  the divided point;  thus  to
arrest the blood, which escapes from  a vein,  it is suffi-
cient merely to maintain  the  edges of the  wound for
some time in contact; but  if, on the other hand, an artery
has been opened,  the vessel must either be tied, or oblite-
rated by compression.

              MECHANISM OF THE  CIRCULATION.
of tChentheart°ns   It is easy to comprehend the mechanism, by
which the blood is moved in all these vessels.   The cav-
ities of the heart, as we have already said, contract and
expand alternately,  and thus drive the blood into  the
canals,  with which they are in communication.
  The  two ventricles contract at  the  same  time, and
when  their  walls  are relaxed, the auricles  contract  in
their turn.   These  contractions are called  the systole2
and the opposite the diastole?   They are very frequently
renewed ;  in the adult man usually from sixty to seventy-
five in a minute ;  in the aged their number appears to be
a little  augmented ; and in very young children it gener-
ally amounts to about  one hundred and fifty.  Besides
the age, a multitude of other circumstances influence the

  1 When death happens, the arteries contract after the left ventricle has
ceased to act, so that the blood then passe.s into the veins and accumulates
there, while the arteries remain empty; for this reason it was so long be-
fore the uses of these latter vessels were known.
  2 2! varolii, from avarellot), I contract.
  3 Aiacnok^\, from diotorsllu, I dilate. 
                      CIRCULATION.                    47

frequency and force of the pulsations of the heart; they
are accelerated by exercise, emotions of the mind, and by
many diseases; in swoons and syncope  they are consid-
erably diminished, or even momentarily interrupted.
   The left auricle, which receives the blood coming from
the lungs, communicates, as we have seen, with the pul-
monary veins on one side, and with  the left ventricle on
the  other;  by its contraction it expels from its  cavity
the greater part of the blood, which  was there ;  and it is
evident,  that this liquid must  tend to escape by  two
ways.   This would take place,  did  not  the ventricle di-
late at the same  time,  and  thus the  greater part of the
blood penetrating into its interior, very  little returns into
the pulmonary veins.
   Soon after,  the ventricle contracts
in its turn, and drives  out the blood
it had just received ;  now, there is
attached around  the  edges  on  the
upper side of the opening,  by which
the ventricle  and  auricle  communi- ,
cate,  a membranous fold, so arranged
as  to sink  down and  open  when
driven  from  above  downward,  and
arise  and shut the opening when driven in a contrary di-
rection ;2 the result is, that during the contraction of the

  1 Section of the heart to show the disposition of the valves, which sepa-
rate the auricles from the ventricles,  a, Auricle opened and extended,  b,
Cavity of the ventricle, the walls of which are supplied with a great num-
ber of fleshy fibres, irregularly disposed, so as to form a kind  of cellules.
c, Valve, whose external border is fixed to the circumference of the auriculo-
ventricular opening, and the free border of which gives attachment to a
great number of little  tendons, {d), arising from fleshy columns fixed to
the walls of the ventricle by their inferior extremity.
  2 This species of valve has been called the mitral valve, on account of the
 
48
ANATOMY AND PHYSIOLOGY.
 ventricle,  the blood cannot return to the  auricle, and is
 driven into the aorta.
   The measure of the force, with which  the left ventri-
 cle drives the blood into the arterial system, to be  sent
 to all parts of the body, has been  the  subject of much
 investigation, which has  given the  most  discordant re-
 sults ;  thus  Borelli, guided by  calculation rather  than
 direct experiment, was led to believe that  this force must
 be  sufficient for  the  equilibrium  of  180,000  pounds
 (livres); while the physiologist, Kiel, estimates it  at  only
 five ounces.  But a young physician, M.  Poiseuille, has
 lately published upon this question better directed re-
 searches, and from which it would appear,  that the force,
 with which  the  heart throws  the blood into the aorta, is
 about four pounds in the human adult, and eleven pounds
 in the horse.
  course of     From the nature of the movements  already
 the blood in                                                J
 the arteries.  Sp0ken of, it would naturally be  supposed,  that
 the blood could only move  in the arteries by jets, each
 time  that the left ventricle contracted,  and  that,  during
 the dilatation of this cavity, it must remain in  repose.
 It is however quite the contrary ; if one of these vessels
 be opened in a living animal, the  blood  is seen to escape
 in a continuous jet, which becomes stronger at the  mo-
 ment of the contraction of the  heart, but  which  is  only
 interrupted by the  opposite movement.   This depends
 on the action of the arterial walls on the  course   of the

 division of its free edge into two  tongues.  The mechanism, by means of
 which it closes the auriculo-ventricular opening, is very  simple ; small ten-
 dinous cords, springing from fleshy columns fixed inferiorly to the walls of
the ventricle, are inserted into its  free border, and prevent it from turning
into the auricle, while they oppose no obstacle to its opening  in the  oppo-
site direction. (Fig. 12.) 
                     CIRCULATION.                  49

blood.   These walls are very elastic ;  when a  wave  of
blood is projected into the aorta by the contraction of the
ventricle, they yield to the pressure thus exercised, in the
manner of a spring, but they tend  afterward  to return
upon themselves, and to drive out the blood, which dis-
tended them.
  To demonstrate the influence of  the  arterial   influence
                                               of the arte-
coats upon  the  course  of the blood, it will be  rialcoats-
sufficient to expose a large artery in the living animal, and
to intercept a portion between two ligatures tightly tied,
then to make a small  opening between the two points
thus obliterated.  The blood in this place will  be com-
pletely isolated from the influence of the movements of
the  heart, and yet it will  escape from the artery in  a
very elevated jet, and  the  vessel will soon be  emptied
by the simple effort of the contraction of its walls.  The
portion of the  artery beyond the  ligature  diminishes in
calibre, and sends into the veins the greater part of its
blood.
   Thus through the elasticity of the arteries, the inter-
mitting movement  impressed on the blood by  the  con-
tractions of the heart, is  transformed  into  a  continuous
movement.  In the large arteries, the jets occasioned by
these contractions may be perceived; but in the capillary
vessels, and even in the small arterial  branches, they are
no longer perceived,  and the blood only flows  through
the  influence of the pressure exercised by the elastic
walls of the arteries.
   We see then, that the  contractions  of the heart serve
to fill continually the great arteries, and, so to speak, to
stretch the spring represented by the walls of these ves-
sels, and destined to expel in a continuous manner this
liquid into the  veins.
                    7 
50            ANATOMY AND PHYSIOLOGY.
   Puise.    The phenomenon, known by the name of pulse,
is only the movement occasioned by the pressure of the
blood upon the walls of the arteries at every contraction
of the heart.  From the  force  and frequency of these
movements we may judge  of  the manner, in which this
organ beats, and draw from it useful inductions for med-
icine.  But the pulse is not everywhere felt; to  dis-
tinguish it an  artery of a certain volume must be com-
pressed between the finger and  a resisting plane, a bone
for instance, and we must therefore  select a vessel situ-
ated near the  skin, as the radial artery at the wrist.
the""ffithe   Although it be the same motive agent which
offlthee",ody!rts drives the blood to all the parts of the arterial
system, nevertheless, it is observed, that this liquid does
not arrive at all the organs with the same rapidity.  The
distance, which separates them  from the heart, is one,
but not the only cause of this difference.
 influence of   Sometimes these vessels go in nearly a straight
the curvature                          °         J
of the arteries. \mG,  at others they form frequent elbows; now
whenever the column of blood, put in motion by the con-
tractions of the heart, meets one of these curvatures, it
tends to straighten the vessel, and thus loses a portion of
its motor force, which diminishes by as  much  the  rapid-
ity of its course.
 influence of   It is a law of physics, that, all other  things
the division of                  l J                       °
the arteries.   Demg equal,  the  rapidity,  with which  a  liquid
flows in a system of canals, is  so  much the greater, as
their calibre is smaller ;  and observation teaches us, that
the total  capacity of the  various twigs  of  an arterial
branch, or of  the various branches of a trunk, is always
superior  to that of the vessels,  whence they  spring.   It
results, therefore, that the more numerous the sub-divi- 
                      CIRCULATION.                   5]

 sions of an artery before penetrating the substance of an
 organ,  the slower must the blood  be conveyed  to  the
 part;  and in this  respect very great differences may be
 observed in the animal economy ;  sometimes  these ves-
 sels are  distributed  to organs only  after  a great num-
 ber of sub-divisions, and sometimes,  on the contrary, the
 arterial trunk buries itself in the substance of the part, in
 which it is to ramify.
   These dispositions, by the aid of which the impetuosity
 of  the blood is moderated at certain  points of the circu-
 latory apparatus, are principally remarked in the arteries
 charged with conveying this  liquid to  organs,  whose
 structure is most delicate, and functions most important;
 the brain, for example.   But nature with her enlightened
 foresight is not confined  to such precautions, to  communica-
      °                         x          '    tion of the ar-
 insure  the arrival  of the  proper quantity ofteries-
 blood  in each of the  parts of the  body.   We can easily
 conceive, that by compression, or  other accidents, an  ar-
 tery may be obliterated at some point of its extent, and
 that if the blood could not then arrive at the organ, in
 which this vessel  is distributed, the death of the part
 would inevitably result, but this does not take place,  for
 most of the arteries have frequent  communications with
 each other, called anastomoses, by  means of which these
 vessels  can receive the  blood  of  a  neighboring artery,
 even if they do not communicate directly with the heart.
  We have  seen  the  mechanism, by  which  the  blood
 passes from  the  heart to all parts of the body ;  let  us
 now study the means employed by nature to  make this
 liquid circulate in  the veins, and to  reconduct  it  to the
heart.
  Again, the  contractions of the left ventricle  c<?»rse. .«*
    o   '                                     the blood, iq
of the heart, and the obstruction of the arterial-tlie veias" 
52
ANATOMY AND PHYSIOLOGY.
 walls, contribute most to the course of the blood in the
 veins.
   If the passage of the blood in an artery be interrupted,
 and the corresponding vein  be opened,  this liquid will
 continue to  flow from the latter vessel,  so long as  the
 artery by its contractions has  not expelled  all  the blood,
 which distended it;  but soon after, the hemorrhage will
 cease, although the vein be yet filled with blood, and the
 flow of this liquid will recommence,  as soon as the cir-
 culation in the  artery is  reestablished.  It is  then  the
 impulse received by the blood at its departure from the
 heart, which causes itself to be felt in  the veins, and
 which  determines  its progress in  these vessels.   But
 there are  other circumstances, which tend to favor this
 movement.
           Fig. 13.1              In  the  veins   of the
               a              limbs,  and  of several other
                              parts   of  the  body,  the
                              membrane   which   lines
                              these vessels, forms a great
                              number of  folds, or valves,
                              which open when the blood
                              drives  them  from the ex-
                              tremities to the heart, and
                              close   so as  to  intercept
                              the  passage, when this li-
                              quid is forced in a contrary
                              direction.  Now,  this  ar-
                              rangement   consequently
                              prevents the  blood  from
  1 Trunk of  a large vein opened to show the valves formed by the folds
of its internal membrane. — a, Superior portion of the vein, — b, valves,
 
                      CIRCULATION.                   53

flowing back  to the  capillaries,  and  also contributes, in
an active manner, to facilitate its  passage to the heart;
for, each time that the vein by the motions of the neigh-
boring parts is compressed, the  blood is driven forward,
and  when the compression ceases it can no  longer be
driven backward,  but is replaced by a new quantity of
liquid  coming from  the  inferior part of the limb.   All
intermitting compression then of these vessels facilitates
the return of  the blood to the heart.
  The dilatation  of  the  chest, produced by the respira-
tory movements in inspiration, in the manner of a pump,
facilitates  also the passage of the venous  blood to the
cavities of the heart,  as  we  shall see when treating of
respiration.
  Nevertheless, the blood flows  much less quickly in the
veins than in  the arteries, and nature  has multiplied the
means proper to prevent the obstruction of one of these
vessels from  arresting the  return  of this liquid to the
heart; there generally are several veins destined to fulfil
the same purpose, and these vessels communicate together
by numerous anastomoses.
  The passage of the blood through the cavities th£avsesa^sof
of the right side of  the  heart is made in the ul0e0Lartr.0SS
same manner as  from the left auricle  to the ventricle of
the same side.
  When the right auricle is relaxed, the blood flows into
it from the two venae cavae;  and when this  cavity after-
wards  contracts, the greater  part  of this liquid passes
into the  ventricle, for there is around the edge of the

the concavity of which is directed towards the heart, — c, venous twigs
anastomosing and uniting to form a large branch, (d), which opens into the
principal trunk at c. 
54             ANATOMY AND PHYSIOLOGY.
opening of these vessels a valve, to oppose the  reflux  of
blood into the  inferior vena cava, and  from its weight
this liquid must tend to  fall into the ventricular cavity,
rather than ascend into the vena cava superior.
   The opening,  by which  the right ventricle communi-
cates with the auricle, is also supplied with a valve1 sim-
ilar to that of the left ventricle ;  and by  its contractions,
this cavity drives the blood into the pulmonary artery, by
raising other  valves which  surround the entrance of this
vessel,  and prevent the blood from returning in the direc-
tion of the heart.2
  Letion.rcuIa"   Finally, the blood passes from the pulmonary
arteries into the veins of the same name, by traversing
the capillary vessels of the lungs,  and enters the  left auri-
cle in the same manner, in which  it moves in  the canals
of the great circulation.
                      ABSORPTION.

   We have seen, that the body of a living animal  must
constantly assimilate to its own substance foreign  mate-
rials, derived  from  the  exterior world, and  must  reject
the particles separated from  its  own organs, and which
can no longer serve to form  them.

  1 Called the tricuspid valve, because it is divided into three triangular
portions ; its arrangement is similar to that of the mitral valve.
  2 These valves, to the number of three, are formed by folds of the inter-
nal membrane of the artery, and are named, from  their form, semi-lunar
valves ; their arrangement is analogous to that of the valves of the veins.
(Fig. 13.)  When the blood is driven from the  heart into  the vessel, they
are raised and applied against the walls of the latter; but when the blood
tends to reenter the auricle, the weight of the liquid distends and closes
them ; they then resemble considerably the little baskets in which pigeons. 
                      ABSORPTION.                    cc

   We have also seen, that a peculiar liquid, the blood,
continually traverses the various parts of  the economy to
convey these materials.
   But this nutritive liquid is  itself contained  in  cavities
within the body, which have no  external  opening;  the
question then arises, by what way the foreign substances,
necessary  for the support of life, can  penetrate into  the
vessels to  be mixed with the blood, and  how the  materi-
als existing in it can escape.  These two orders of phe-
nomena  constitute the functions of absorption and  exhala-
tion, with  which we are now to be occupied.
   Absorption is the act,  by which living  beings  Definition.
in some  way suck in, and make penetrate  into the mass
of  their  humors, the substances which surround them, or
are deposited in the interior of their  organs.
   To prove the existence of this absorbing: fac- F">ou of the
      x                                  a     existence of
ulty, a small number of experiments will suffice. absorPtion-
If the body of a frog  be plunged into water, so that none
of this liquid can enter the mouth of the animal, never-
theless at the end of a certain time its weight is found to
have been augmented; now, this  increase, which under
favorable circumstances amounts to  a third of the total
weight of  the  animal, can  evidently depend  only upon
the  absorption  of the water by the  external  surface of
the body.
   If a known quantity of water be introduced into  the
stomach of a dog, and by the aid of two  ligatures all  the
openings, by which the  cavity of this organ  communi-
cates with other parts, be closed, the liquid will yet dis-
appear at the end of a little while, for it will be absorbed

are hatched;  and as they touch at their free edges they close the artery.
Similar valves exist at the entrance of the aorta, where they serve to  pre-
vent the blood from reentering the left ventricle, while this cavity dilates. 
5(j             ANATOMY AND PHYSIOLOGY.

by the walls of the stomach, and  thus mingled with  the
blood.
 ofltaSI™.   And yet there do not exist on the surface of
the skin, or stomach, any pores' or openings conducting
directly to the  blood-vessels, and which  may serve for  a
passage to the liquids absorbed.   But the tissues,  which
form these organs, as well as those of all other  parts of
the body,  have a structure somewhat  spongy,  and  are
more or less permeable to liquids.
 imbibition.     In the living, as  wTell as the dead  body, these
tissues always imbibe the fluids, which  bathe them,  and
allow themselves to be traversed with more or less facility.
                            Thus,  if a current of acidula-
                         ted water  be made to traverse
                         a  section of  a  vein,  arranged
                         as  in  the  figure,  the  external
                         surface of  this  vessel being in
                         contact with a  solution of tour-
nesol, the color of the latter liquid will  soon be changed
to red by the action of the acid, which has passed through
the walls of the  vein.   In  the dead body consequently
these parts are permeable to liquids.
   Now, if wre  expose a vein  in the  living  animal,  per-
fectly isolate this vessel, and apply  upon its exterior  sur-
face the  extract of nux vomica, this violent poison  will

  1 The pores, which are perceived  upon the surface of the skin, do not
traverse this membrane, but only conduct to small  cavities lodged in  its
interior, and serving to secrete various humors, or to form the hair;  when
treating of the touch we shall have occasion to return to  the structure of
the skin.
  1 a, Flask with two openings containing the acidulated water, and serv-
ing as a reservoir;  b, vase containing the blue solution of tournesol into
which is plunged the median portion of a vein, one extremity of which
communicates with the reservoir, a, and the other with the vase, c, which
receives the acidulated water flowing through the vein.
 
                     ABSORPTION.                   57

soon penetrate the membranous walls of the vein, mingle
with the blood, and occasion the terrible symptoms, which
are observed, whenever  it is directly  injected into  the
blood-vessels.  It is  then evident,  that, during life  as
well as after death the veins  are permeable to liquids.
   The permeability of the solid parts of organized bodies
will at once explain to us in  what manner absorption is
possible.  By the aid of this property of the  living  tis-
sues, the liquids may have access every where  ; but this
would  not be enough, and, that they may penetrate into
the interior  of the organs,  they must be  attracted by
some force.
   The  capillary action contributes powerfully to  capillarity.
produce this imbibition ;  but it is not the only force which
acts in  this  way; and to form  an exact idea of  the me-
chanism, by means of which liquids penetrate the  sub-
stance of the organic tissues, we  must understand a very
curious phenomenon,  recently discovered by M. Dutro-
chet, and named by him endosmosis.
   This physiologist has proved, that, if a   Endosmosis.
solution of gum be inclosed in a small mem-   * lS-
branous sac surmounted  by a tube, and sur-
rounded by  pure  water,  the latter liquid
will penetrate into the interior of the appa-
ratus, and ascend in the tube to a consider-
able height.   Here then there is a true ab-
sorption, and the  force, which  determines
it, acts often with such energy as to consti-
tute the equilibrium to a column of water of
several centimetres.   If,  on the contrary,
gum or sugar-water be  placed without the
membranous sac, and pure water in its in-
                   8
 
58            ANATOMY AND PHYSIOLOGY.

terior, the  passage  takes place inversely, and  the sac,
instead of filling, is emptied.
  This phenomenon is very analogous to the  absorption
which takes  place in  living beings, and the explanation
is easily given.  We have  seen, that the organic mem-
branes, as well as all the spongy and porous bodies, may
be traversed by liquids ;  but the facility of this transport
varies  with the fluidity of these liquids, and the  ease
with  which  they  imbibe  the filtrations.  If  the two
liquids placed in the interior,  and upon  the exterior  of
the membranous sac, could  traverse equally well the
walls  of this  cavity, they would  mingle, and the  same
level be established upon either side.  But  if the  exte-
rior liquid traverse more readily the walls of the  sac than
the interior,  the current from without  inward  will be
more rapid than the current in a contrary direction, and
the liquid will accumulate in the interior of the  appara-
tus.   Now, this takes  place  in  endosmosis; the water
surrounding the  sac which  contains  the  gum-water, fil-
trates easily through the walls of this cavity, and when it
has reached the interior, it unites with the gum, and thus
forms a new liquid, the passage of which through  these
walls is difficult in proportion to the  quantity of gum.  It
must then  accumulate, and  ascend  in the vertical  tube,
which communicates with the  membranous reservoir.
  The organized  bodies, which  absorb  the  liquids by
which they are surrounded, are placed in the same con-
ditions with the  membranous sac, of which we have now
spoken ;  the presumption then is, that in all these  cases
the same effects arise  from analogous causes, and that
the principal force, which occasions  the passage of the
absorbed substances across  the living membranes, is the 
                     ABSORPTION.                    rg

same with that,  which  produces  the phenomenon of
endosmosis.
   In certain  animals  of  the inferior  classes,    Transport
 1       . ,                                     °f tne absorb-
those with the least  complicated structure and ed !iquids-
most limited  functions, absorption  consists  only in the
kind  of imbibition, of which I  have  spoken.  By the
same mechanism  foreign  substances traverse the  solid
parts, with which  they are in contact, to be mingled with
the  liquids, by which the  areolae  of these  organs are
filled, and are afterwards diffused through all the  body
and  penetrate the interior  of the  tissues.   But as we
ascend  in  the series  of beings we soon see  that nature
perfects the mechanism of absorption, and that to accom-
plish this, she introduces into this important function a
constantly progressive division of labor.
   In the animals  possessing a  regular circula-  AS$*n?
tion, the absorption properly so called, or  the  passage; of
foreign  substances from without  into the  interior of the
economy, is always effected  in  the  same manner  as in
beings  less perfect;  but from the  moment when  these
substances are mingled with the nutritive juices of the
body, a great  change takes place ; instead of being  grad-
ually diffused  to the various  parts by the effect of imbibi-
tion, they are  taken up by currents  more  or less  rapid,
and  immediately distributed to all  the points, to which
the blood penetrates.   We see then, that  the absorption
of these materials, and their transport to  the interior of
the economy,  are no  longer  a single  act, but are  com-
posed of two series of phenomena perfectly distinct; the
first, purely local, consists in the imbibition of the tissues,
and  in  the  mingling of the matters  absorbed with the
humors  of  these parts; the  second, dependent upon the 
(50            ANATOMY AND PHYSIOLOGY.

general circulation, consists in the transport of these same
substances to parts remote  from those, at which they
originally penetrated.
  sVorPntion.ab~  In  all  these beings  the principal agent by
which this transport is effected, is the blood, which trav-
erses the organs in which absorption  takes place,  and
which returns again to the heart, to be afterwards con-
veyed anew to the  interior of the various tissues.   It fol-
lows that, in animals provided with a circulatory system,
the veins perform  a very important office in the absorp-
tion ; and that,  in  the  immense majority of cases, it is
by their intervention, that the liquids, by which a circum-
scribed  part  of the body is surrounded,  are  diffused
through the whole  economy.
  absorptfon0.   In  vei7 many  animals, absorption  is  only
effected through the blood-vessels ;  but in man, and most
animals with  the more  complicated organization, there
exists another system of canals, which answer the same
purpose,  and which serve especially  to  absorb   certain
substances.  This  is the apparatus of the lymphatic ves-
sels.
   This name is given to canals,  which  spring from very
minute radicles  in the interior of the different organs, but
afterward unite in trunks of varying size, and  finally
empty into the veins near  the  heart.   Many physiolo-
gists regard these canals as the sole agents of absorption,
and call them absorbent vessels ;  but this opinion is with-
out foundation.   Comparative anatomy alone would over-
throw it, and the  experiments  of  Magendie and many
others prove it to be completely erroneous.
  proofsofthe   The absorption  by the  veins  is  as  easily
venous absorp-             i       j                        j
tion.       proved in all animals with a  system of  lymph- 
                      ABSORPTION.                  ft]

atic vessels, as in those without.  The following experi-
ments can leave no doubt in this respect.
  Messrs. Magendie and Delille, having  stupefied  a dog
with opium, to render him insensible to the pain occa-
sioned by a  laborious  operation, amputated one  of his
thighs, leaving  only the  artery and vein untouched, to
maintain the communication  between the limb  and the
rest  of the  body ;  then  they deposited within the  paw
thus  separated  a violent  poison (Upas  Tieute).    The
effects of the  poison  were  manifested  with the  same
promptitude and intensity, as if the limb had not been
severed from the body ; and the animal perished in a few
moments.
   It might be objected that,  notwithstanding the precau-
tions taken, the untouched coats  of the  artery and  vein
contained in their tissues the lymphatic vessels, and these
canals were sufficient to  give passage to  the poison.
   To  remove this difficulty M. Magendie repeated the
experiment upon another dog, with this modification, that
he introduced into the  femoral artery a quill,  to which he
fastened the  vessel by two ligatures, he then divided cir-
cularly between the two the  walls of the artery,  and per-
formed  the  same  operation  upon  the vein.  The  only
means of communication then, between  the thigh  of the
animal and  the remainder of his body, were, the arterial
blood coming to the limb, and the venous blood returning
to the heart; yet  the poison  then introduced  into the
paw produced death with its ordinary rapidity.
   This experiment leaves no doubt, but that the  poison
passes from the paw to the trunk through the crural vein ;
and to render the proof  yet  more  conclusive, it will be
sufficient to press this vein between the fingers  at the 
g2           ANATOMY AND PHYSIOLOGY.
moment when the effects of the poison begin to be man-
ifested ; for by  thus impeding the passage  of  the  blood,
the symptoms of  poisoning cease at once, to reappear  as
soon as the vessel is again left free, and the blood allow-
ed to ascend  to the heart.
  In other experiments,  the  presence of the materials
absorbed has been directly proved in the blood  of the
veins.   It is  then evident, that these vessels  are active
organs of absorption,  but  it cannot be doubted, that the
 proofs of the lymphatics in  certain cases  discharge the same
lymphatic ab- J  *                               t     .
sorption.    duties.  As  we shall hereafter  see, these latter
ducts are especially charged with the transport of the nu-
tritive materials, extracted from the aliments by the labor
of digestion,  and in the other  parts of the body they ap-
pear  to  fulfil  analogous  functions.   M. Dupuytren,  in
making the autopsy of a patient, who sank under an enor-
mous abcess of the thigh, found the neighboring lymph-
atic vessels distended by a liquid, having all  the charac-
ters of pus.  And it  has  for a long time been known,
that, if  when dissecting  a  putrified  body an individual
prick his  finger,  there often arise  grave  accidents  from
the absorption  of the substances thus inoculated, and it
is  not rare to see the lymphatic vessels, which extend
from the wound to the trunk, swollen, and inflamed, as
if the passage of  the poison had irritated their walls.
   Moreover the  absorption by the  lymphatics must  be
slower than that  by the veins ; for the blood  flows with
great rapidity in  these latter canals, and  the  liquid con-
tained in the lymphatic vessels moves but slowly.
  Lymph.   This  liquid is called the lymph.   Its  physical
properties are not always the same ; sometimes it is opa-
line, and of  a faint  rosy tint;  at others yellowish, and 
                      ABSORPTION.                    no

sometimes red ;  examined by the microscope, a multitude
of small globules are seen in it analogous to those of the
blood, and when left to itself it coagulates like the latter,
and separates into two parts, a  serous fluid, and a solid
clot, which exposed to the action of the air takes a  red
tint.1
   The lymphatic vessels resemble the veins  in  L^£ic
their structure  and mode  of distribution, but  they are
much  finer, and  their walls thinner.  They are met with
in nearly all parts of the body ; they form in general two
planes, one superficial, the other deep seated ; they com-
municate by frequent anastomoses, and unite in twigs
and branches like the veins.  The majority of these ves-
sels thus form one large trunk .(called the thoracic canal),
which ascends in front of the vertebral column, and emp-
ties into the subclavian  vein of the left side ; but  others
open separately into the vein on the opposite  side  of  the
neck, or even sometimes into the different blood-vessels,
situated nearer  their origin.  During their  course they
are seen to traverse little organs, irregularly rounded, and
situated in  the  axillae, groin, neck, chest  and abdomen.
(See Fig. 25.)   The structure and uses of these  bodies
are yet but little known ;  they are called ganglions, or
lymphatic glands.   Finally, in the interior of  the lymph-
atic vessels  there  exist a  great  number of  transverse
folds, which discharge the  same  functions as  the  valves
of  the veins, and which oppose the reflux of  the lymph.
   From what has  already  been  said upon the  nrcumstan-
                        J             l        ces influencing
mechanism of absorption, it will readily be per- absorPtion-

  1 By chemical analysis the clot of the lymph has been found to be com-
posed as follows, viz.: water, 925 ; fibrine, 3; albumen, 57; alkaline, chlo-
rides, soda and phosphate of lime, 14 ; to the thousand parts. The propor-
tion of the clot to the serum appears to be nearly as 1 to 300. 
g4            ANATOMY AND PHYSIOLOGY.

ceived, what the principal circumstances are which influ-
ence the course of this function.
 permeability   Thus, the first condition of all absorption be-
and vasculari-                                     .         i
suefthe tis" mg the  permeability of the tissues  interposed
between the substance to be absorbed,  and the liquids
which are to effect its transport; it is evident, that, other
things  being equal,  this phenomenon will be  rapid  in
proportion to the lax and spongy texture of this  tissue  it-
self, and the degree  of vascularity, which is the seat of it.
  In truth,  the lax  and  spongy texture of the  organic
solids is  of  all the  physical properties, that which most
facilitates imbibition ;  and with regard to the veins, since
by  them principally  the  absorbed substances are diffused
in the  economy, the influence of their number  and size
is too evident to require any comments.  In  the major-
ity of cases, these two laws will explain to us the great
diversity, observed in the rapidity, with which absorption
is effected in the various parts of the  body; we  might
even anticipate this  difference from the sole consideration
of the anatomical disposition of our organs.
   Thus the lungs, the structure and  functions  of which
will be examined hereafter, are of all parts of the econo-
my those, in which  the  structure is most spongy, and the
vascular system most developed.   It follows, that absorp-
tion must be more rapid in these organs than elsewhere,
and to this  result does experiment lead.
    The  soft and whitish substance, which is found  be-
 tween all the organs,  and which is called the cellular  tis-
 sue, is also very permeable to liquids,  but possesses  far
 fewer blood-vessels than the tissue of the lungs;  there-
 fore absorption, although very rapid, takes place less rap-
 idly than in these organs. 
                     ABSORPTION.                    gc

  The skin presents, on the contrary, a very dense  tex-
ture,  and  its surface is  covered  by a kind of varnish,
formed  by the epidermis;  in  general,  its blood-vessels
are small and few ;  and, as might  be expected from this
anatomical disposition, absorption takes place with  great
difficulty.   By raising the epidermis, imbibition  is con-
siderably facilitated, and consequently absorption is  ren-
dered more easy ; finally, when we do  not confine  our-
selves to simply stripping the dermis, but also excite its
vascular system, (by the irritation of a blister, for exam-
ple) this function is rendered yet more active.
   In medicine, use is made of this fact to obtain the ab-
sorption of  certain  substances,  whose irritating nature
upon the stomach is feared, and this mode  of administer-
ing remedies is called the endermic method.  The slight
degree of permeability of the  epidermis also explains  to
us how the most  violent poisons  may  be made use  of
without danger, provided the skin  of the  hands  be un-
touched ;  for  in  them  absorption  is nearly null; while
the gravest accidents, and  death itself, may result from
the contact of these same substances at any point, where
the skin has been wounded, or  merely deprived of the
epidermis.
  Another circumstance, which also  exercises a  Mh^n°0rrsthe
great  influence  upon the rapidity  of absorption,  is the
state of plethora of the animal.1
   The  quantity of liquid,  which  may be contained  in
the body of a living animal, has limits as well as the de-
gree of desiccation,  compatible with life.   Now, the
nearer the body approaches its  point of  saturation, the
  ' The word plethora (nlyd&Qu, nlrfiw, I fill) is employed to indicate the
state of plenitude of the vascular system.
                    9 
66
ANATOMY AND PHYSIOLOGY.
 greater difficulty do the liquids experience in reaching its
 interior.
   Thus, if to two  dogs  equal doses of a poison be ad-
 ministered, the  effects of which are not  manifested  till
 after absorption; and if previous  to this operation, the
 mass of humors in one  of these animals be diminished
 by a copious bleeding, while in the other, the volume of
 liquids contained in the body be increased by the injection
 of  a certain quantity of  water into the veins;  the effects
 of  the  poison will  take  place sooner in the former than
 in ordinary cases, and in the latter those symptoms, which
 denote  the absorption of  the  poison, will  not  appear for
 a much longer time.
   These  results are more important to  be known, as
 they meet with  constant application  in  the healing art,
 and show how much the functions  of living beings are
 subject to the ordinary laws of physics.   The  researches
 of my brother, Dr. W. Edwards, relative to the influence
 of physical agents  upon   life, have  fully established this
 truth, and  M. Magendie  has arrived at the same result
 by  following a different course.
aS(ed0fSuhbe   L^tiy*  the nature of the substances absorbed
         also exerts an  influence upon  the ease, with
which they penetrate into the interior of  the tissues, and
are carried into the current of the circulation.  In gene-
ral  thesis we may say, that cceteris paribus, the  absorp-
tion will be so  much the more rapid, as  the liquids are
less dense, and readily moisten the tissues.   In  order that
a solid may be  absorbed, we  must consider in the  first
place its degree  of  solubility, and next, the physical pro-
perties of the solutions it  forms.
  Thus, if water be  injected into  the abdominal cavity 
           EXHALATION AND THE SECRETIONS.         Q*f

of a living animal, this  liquid will  promptly disappear ;
while oil, placed in the same condition, is not sensibly
diminished in volume for a considerable lapse of time.


   Such are the  most important points  in  the  history of
absorption.   Let us now study the inverse function, that,
by which a  portion of the substances contained in  the
general mass of the humors, and enclosed with them in
the blood  vessels, can  escape, either to penetrate  the
cavities within the body, or to make its way externally.
        EXHALATION AND THE  SECRETIONS.

   The passage of the fluids from the interior of the ves-
sels  outward, may take  place  in  three different ways ;
sometimes a portion of the blood itself is expelled from
these canals with all  its constituent parts, which is called
a  sanguineous effusion ;  in  others, merely  a  portion  of
the aqueous part of the blood  issues from the vessels,
carrying with it a certain quantity of the soluble  mate-
rials, already existing in the liquid, and this  phenomenon
is  styled exhalation ; lastly, there are also  times, when
there are separated from the blood  new products,  which
differ from it  by  their acidity, or greater alkaline proper-
ties, and which often contain in  abundance substances,
of which but the slightest trace exists in the blood.   This
labor, in some sort chemical, constitutes what is  called
by physiologists a secretion. 
68
ANATOMY AND PHYSIOLOGY.
          TRANSUDATION. OR SANGUINEOUS EFFUSION.
  The mechanism,  by the aid of which the blood  is
effused from the vessels to escape externally, or to flow
into  the  cavities within the body, is very simple.   In
some parts of the economy the veins communicate with
a peculiar spongy tissue by means of openings, which in
the state of repose are not open,  but which afford a free
passage to the  blood, if any obstacle whatsoever, by op-
posing its  ordinary  course, determines  its accumulation
in the veins.   By such a  process does the erectile tissue,
which forms various  appendages around the head of tur-
keys, for example, swell, extend, and take an intense red
color.
   At other times, the sanguineous effusion  takes place
without any such perceptible openings to  the veins;  and
then this liquid  appears to filtrate through the substance
of the  tissues;  this is observed but in a small number of
cases, and generally arises from a  pathological  condition.

                      EXHALATION.
   Exhalation  is equally  a physical  phenomenon,  the
course of which may be  modified by the action of the
vital forces, but its existence is independent of them.
theexKonf  ^'e  have  already seen, that the walls of the
blood vessels, as well as the other parts of the body, are
permeable to  liquids ; now we can easily comprehend,
that the  most fluid part of the  blood  must traverse them
much more readily than  the solid corpuscules contained
in this liquid, and  that, by acting as a filter, these mem-
branes  must produce  the  phenomenon  of  exhalation. 
           EXHALATION AND THE SECRETIONS.         go,

This  actually takes place, both in the dead and living
body ; if there be thrown into the arteries of a dead an-
imal a solution of gelatine, colored by vermilion reduced
to a very  fine powder, the injection  will penetrate the
capillary vessels, and then we often see a portion of wa-
ter traversing their walls  loaded with  gelatine,  to escape
externally, while the coloring matter  is retained in their
interior.
   The mechanism of exhalation is the same with that of
absorption ; all  the  parts, which  are  the seat  of one of
these functions,  may be  of the other: in  general they
take place simultaneously, and  every  thing, which tends
to modify the course of one, influences the other.
   The degree, to which  the texture is spongy, SIS*^^
   j  r                1    r     i 1  ,  • i «i •  enre exhala-
and of course more or Jess favorable to imbibi- uon.
tion, is a condition, acting equally upon absorption  and
exhalation.   These functions, cceteris paribus, are active
in proportion to the number of blood vessels traversing
their seat.
   The variations in the mass of the liquids contained in
the body act, on the contrary, in an inverse manner upon
these two functions, the  greater the quantity of liquids,
the more abundant the exhalation.   In  the  living body
as in the dead, the tissues retain water more powerfully,
the less they contain, and by increasing  the mass of hu-
mors we can at will make active the exhalation.
   Finally, the pressure, which the blood supports in the
vessels, also  exerts a powerful  influence upon the exha-
lation ;  and when the circulation in  the veins is inter-
rupted,  so as to  cause  the accumulation of this liquid,
the more fluid portion of  the blood exhales in abundance
into the  neighboring parts,  and causes  them  to swell, 
 70            ANATOMY AND PHYSIOLOGY.

 which  produces the  tumidity of those parts, which have
 been closely surrounded by ligatures.
  External and   Exhalations are divided into external and in-
 lnternal exha
 lations.    ternal, depending upon  the  fact, whether they
 take place on the general surface  of the body, or in cavi-
 ties, which have no free external communication.
   The exterior exhalation, which must not be confounded
 with the perspiration, and which takes  place on the pul-
 monary surface, as well as upon the skin,  is also styled
 insensible transpiration, because its products are dissipa-
 ted  by  evaporation, and are not usually appreciable to our
 senses.  The losses experienced by man and other ani-
 mals in this way are  very considerable.   In the state  of
 health,  the weight of the body  of an adult hardly varies,
 and  the losses, which he experiences by the various ex-
 cretions, counterbalance the weight of the aliments daily
 used by him ; now from the experiments of Sanctorius it
 appears, that insensible transpiration   often constitutes
 five  eighths of the total losses, of which  we have spoken.
   However, the evaporation, going on upon the surface
of the body, does  not always  take  place with  the same
intensity, and even here the influence of physical  agents
is felt in nearly  the same manner upon  the  living and the
dead.   In both, the losses by evaporation are augmented
by the elevation of the temperature, agitation of the air,
(winds, etc.)  by its  dryness, by  the diminution  of the
atmospheric pressure, etc.
  The internal exhalations take place upon the  surface of
the  walls  of  cavities,  varying  in  size, situated  in the
interior of the body, and they also consist of water, min-
gled with a small quantity of animal matter,  and salts
contained in  the blood, whence  these liquids  escape. 
EXHALATION AND THE SECRETIONS.
71
Such is the source not merely of  the humors which  con-
tinually moisten  the serous membranes,1  by which the
great viscera of the  head, chest, and abdomen  are envel-
oped ;  but also of the serosity,  which bathes the lamellae
of the cellular  tissue, so abundantly diffused in all parts
of the body ;  and of a part of  the humors, which fill the
interior of the  eye.
   As these internal  exhalations take place upon the sur-
face of cavities, which have no  outlet, it  is  evident,  that
the quantity of liquids contained  in  this species of reser-
voirs would constantly augment, if the parts, thus exhal-
ing, were not at the same time the seat of an absorption
not less rapid.   In the state of health,  these  two func-
tions are  exercised  simultaneously, and  counterbalance,
so as to maintain always the  same  quantity of liquid in
the interior of the cavity ; but sometimes this equilibrium
is destroyed, and exhalation  becomes more active  than
absorption ;  the liquids then accumulate in the  parts, and
diseases result known as Dropsies.2

  1 The disposition of the serous membranes requires attention ; they have
always the form of a species  of sac, whose  internal  surface extremely
smooth and moistened constantly by a liquid, is everywhere in contact with
itself ; one of the halves of this sac adheres by its external face to the walls
of the cavity lodging the viscera, and the other half surrounds these viscera
and adheres to them by its external face. To make use of a  trifling com-
parison, but  one which perfectly represents the thing,  these membranes
resemble a double night-cap, and surround the viscera as this cap the head,
the exterior surface of which should be  fixed to the walls of  a cavity con-
taining both  the cap and the head.  These membranes  serve to diminish
the friction of these parts, and consequently to facilitate the»ir movements;
therefore similar sacs are met with wherever  the organs continually, or
forcibly, rub against each other, as at the articulations of the bones of the
limbs, around the intestines, etc.
  2 These collections of water are variously denominated according to the
parts, which  are the seat of them ; the special name of dropsy (or ascites) is 
72
ANATOMY AND PHYSIOLOGY.
                       SECRETIONS.
   The secretions differ essentially from the  exhalations,
in that the liquid separated from the blood is  not merely
water, or serum, but a  humor, the chemical nature  of
which is wholly distinct  from  that  of the blood, or its
serum.
 wcreuon°.f.the   The blood,  as  we  have  already  seen,  is
slightly alkaline ;  the liquors secreted are  sometimes very
alkaline, at others acid ;  and in them we  find particular
substances, not existing in the blood, or in quantities too
small to be appreciated by our means of analysis.  Here
then chemical action takes  place, and  by comparing the
phenomena of the secretions with those produced by the
action of the voltaic pile, a striking analogy  may be ob-
served.  If an electric current be passed through a liquid,
holding  in  solution  salts and  albumen, serum for exam-
ple, there is formed at one pole of the pile an acid, and
at the  other an  alkaline  liquid,  and animal substances
dissolved in it are seen to change their nature.   Now, it
is  precisely the same with the  secretory organs; and by
admitting, that the one are seat of the  positive,  and the
others of the negative pole  of  an  electric apparatus, the
greater part  of the phenomena met with would be ac-
counted for very easily.   But this theory, plausible  as it
is, cannot be received until based  upon facts, and unfor-
tunately these facts are wanting.
given to accumulations of water in the cavity of the abdomen ;  and hydro-
thorax, or dropsy of the chest, to such as are formed in the pleura, the mem-
brane surrounding the lungs ; dropsy of the heart, such effusions as take
place into the pericardium, the membrane around the heart; hydrocephalus,
those in the membranes covering the brain ; and ozdema, those exhibited in
the cellular tissue of the various parts of the body. 
           EXHALATION AND THE SECRETIONS.        70

   However, the secretions are not made indif-  Secre,ory
           '                                   organs.
ferently in all parts of the body as the exhalations;  they
always have  their seat  in  special organs,  which  have
a  very peculiar mode of structure.   They are always
composed of a greater or smaller number of extremely
minute cavities, in the form of pockets, purses, or canals,
of very great tenacity, and which receive a great number
of blood-vessels, as well as  of nerves.  They are desig-
nated by the general  name of  glands,  and  divided into
perfect and imperfect, according as they are furnished with
a duct through which the product of  their secretion is
poured out, or as they have the form of cavities without
openings, and from which the  liquids  secreted can  only
issue by absorption.
   The disposition of the perfect glands greatly varies ;
some are situated  near the surface of various membranes,
and  open directly  into them, without having an excretory
canal  in the  form of a  tube  : these  are called simple
glands, or  crypts.   Others consist  of masses of crypts,
which empty the products of their secretions by several
openings;  these  are  the agglutinated glands.   Lastly,
others still present excretory ducts in the form  of  rami-
fied  tubes,  and which unite into a  small  number of ca-
nals ; they bear the name of conglomerated  glands, and
in the course of their excretory duct, there is sometimes
found a membranous  pocket, serving as a reservoir for the
liquid secreted.
   As an example  of  the crypts we will cite  the  follicles
scattered  upon the mucous  membrane of the  digestive
canal, also  those  which  open  upon the  surface of the
skin, and secrete the  fatty and  unctuous matter, by which
the hair is moistened; the tonsils belong to the class of
                  10 
74
ANATOMY AND PHYSIOLOGY.
the agglutinated glands ; and the liver, kidneys, salivary
glands, etc. to the  conglomerated glands.
   The imperfect glands are formed by little pouches  dis-
seminated in the cellular tissue, or collected in masses of
varying volume.   The organs, which secrete  the fat,  and
which are lodged  in the interior of the  cellular  tissue,
present the  former of these dispositions ; in very lean
persons it is  difficult to  distinguish   them,   and  they are
confounded with the cellular tissue;  but when filled with
fat, they  are  seen  to be formed of a very thin  membrane,
rounded in form, without opening.1

  1  The fat is essentially composed of two particular materials, elaine and
stearine, one liquid and  the other solid  at the ordinary temperature; the
relative proportions of these two substances vary greatly in different ani-
mals, and hence  corresponding differences in the consistence of their fat.
In general,  the principal uses  of this matter are all mechanical, and it
serves as an elastic cushion to protect the organs it surrounds; this is seen
in the orbit, where the eye reposes upon a thick bed of fat,  on the sole of
the  foot, where it is also found in considerable quantity, and in other  parts
of the body exposed to constant pressure, or friction. It may also, from its
feeble power of  conducting caloric, contribute to  preserve  the heat disen-
gaged in the interior of the body ; finally, it may be considered as a kind of
reserve of nutritive materials deposited in certain parts of the body, in order
to serve the purpose of assimilation, when the animal can no longer derive
from without the substances necessary for  the maintenance of life; when
fat persons remain a  long time without  eating, their fat is gradually ab-
sorbed, and appears to serve for their nutrition; it is also remarked, that
the  hibernating animals, which  pass a great part  of the cold season in a
state of lethargy, are surcharged with fat when they become stupid, and
are  on the contrary very lean when they awaken from their sleep of many
months.  Fat is  not deposited with the same  facility in all parts  of the
body; it abounds especially in the folds of the mesentery, (a portion of the
peritoneum which envelopes the intestines,) around the kidneys, and under
the  skin.  Repose  exercises a  great influence upon its formation; very
young children are usually very fat, but when they begin to take much ex-
ercise, their fat is gradually dissipated, and while the body rapidly increases
it is rarely deposited in considerable quantities. 
                       RESPIRATION.                     75

   Among the imperfect and massive glands we will  cite
the thyroid body,1 and the thymus,2 organs, whose uses
are not yet known.
   The liquors  produced by the secretions are,  "Tet'ed.
as we have said, acid or  alkaline.   The most  important
alkaline humors  are  the  bile, formed  by the liver ; the
saliva,  produced by the salivary glands ; and  the  tears,
secreted  by the  lachrymal  glands.   The principal acid
humors  are the  urine, elaborated by the kidneys ;  the
perspiration, which distils from the follicles of  the  skin ;
the mucus, which lubricates the  mucous membranes, and
issues from the crypts so  abundant upon their surfaces ;
and the milk, which is secreted  by the mammary glands.
Hereafter we shall be obliged  to return to  the study of
these liquids,  and to point out their properties and  uses.
                      RESPIRATION.

   Having investigated  the manner, in which circulation,
absorption, and exhalation  take place, we may turn our

  1 The thyroid body is an ovoid mass, soft, spongy, and glandular in ap-
pearance, situated at the anterior and inferior part of the neck, in  front of
the trachea.  It is in general larger in the infant than the adult, and exists
in all the mammiferse, but is wanting in birds, most reptiles, fishes, and
other animals of the inferior classes. The swelling of this body constitutes
the tumor called goitre.
  2 The thymus is a glandiform mass enclosed within the chest between
the two folds of the anterior mediastinum, (a cavity formed by the union of
the exterior surfaces of the pleurae, and which  lodges the heart.)  It is ex-
tremely developed in the foetus; but soon after birth its volume is much
diminished, and in the adult it is completely atrophied. 
76
ANATOMY AND PHYSIOLOGY.
attention to the study of another  function, the history of
which is closely united with that of the  blood, and  in
importance not inferior  to it:  I  mean the respiration.
  We have  seen, that  the  arterial  blood,  by its  action
upon  the living tissues,  loses the qualities,  which render
it proper for the maintenance of life, and that after being
thus modified,  it resumes,  by contact with  the  air,  its
former properties ;  this contact  is then necessary to the
existence of living beings.  And, if an animal be placed
under the receiver of an air pump, in which a vacuum is
created, or if it be deprived of air  by any other means,
a great trouble at once arises in the  various functions ;
the action of all the  organs is soon interrupted, life ceases
to be  manifested, and the animal  falls into a state of  as-
phyxia, or apparent  death ;  at last, life becomes entirely
extinct, and can  no  longer be recalled.
  This phenomenon is  one of the most universal in  or-
ganic nature ;  the contact of air  is indispensable to  all
animals as well as vegetables, and a living being deprived
of it always dies.  Wherever there is  life, air is  neces-
sary.
  At  first one would suppose, that the animals living  at
the bottom of the water, as fishes, were withdrawn from
the influence of the  air, and consequently  exceptions  to
the law just given ; but it is  not so,  for  the liquid,  in
which they are plunged, absorbs and  holds in solution a
certain  quantity  of  air, which  they can easily  separate,
and which suffices for the support of life.   It is impossi-
ble for them  to exist in water  destitute  of air, for they
are asphyxiated,  and die in the  same manner as mammi-
ferae,  or birds,  when withdrawn from the  action  of the
atmospheric air under its ordinary form. 
                     RESPIRATION.                  77

  The relations of the air with organized beings form
one  of the  most important  parts of their  physiological
history, and  the series of phenomena, which result from
it, constitute the act of respiration.
  Air, we say, is  necessary to the life of all  The vivify-
             J             J                   ine; properties
animals,  but this  fluid is not  a homogeneous pt„dleUp0n the
body; chemistry has demonstrated in it the ex-S"™™"
istence  of very different  elements, and  which  conse-
quently cannot take the same office in the performance
of respiration.   Besides the  watery vapor, with which
the  atmosphere is  always more or less loaded, the air
furnishes  by analysis twenty-one hundredths of oxygen,
and  sixty-nine hundredths  of azote, as well as traces of
carbonic  acid gas.  The  first question, which presents
itself to the  mind when we enter upon the study of res-
piration, is  to know, whether these different gasses act
in the same manner, or if to one in particular belongs the
property of sustaining life.
   To ascertain this a small number of experiments will
be sufficient.  If  a living  animal be placed in a vase,
filled with air, and all  communication  of this fluid with
the atmosphere be  intercepted,  at the end of a longer or
shorter  time the  animal  will become asphyxiated, and
perish.   The air, which  surrounds  it,  has  then lost the
faculty of sustaining life, and by chemical  analysis it is
found to have lost at the  same  time  the greater part of
its oxygen.  If another animal  be  placed in a  jar, filled
with azote,  it also perishes ; while a third  animal put
into oxygen breathes with more activity than  in the air,
and   presents no  symptom  of  asphyxia.   It is evident
therefore, that the  atmospheric  air owes its  vivifying pro-
perties to the presence of  oxygen. 
78             ANATOMY AND PHYSIOLOGY.

  The  discovery of this important fact  dates only from
the close of the last century (1777), and is  due to one
of the most celebrated  French chemists, Lavoisier, who,
notwithstanding his numerous titles to public favor, per-
ished prematurely a victim of the revolution.
Ca^lucct"  By the act  of respiration, we have  said, all
animals remove from  the  air, which  surrounds them, a
certain  quantity of oxygen ; but  the  changes,  they thus
determine  in  the  composition of this  fluid,  are not so
limited ; the oxygen, which  disappears, is replaced by a
new gas, carbonic acid.   The production of  this sub-
stance is not less universal among animals, than the ab-
sorption of oxygen ; and in these two phenomena essen-
tially consist the performance of respiration.
  To prove this  fact, we  have only  to  blow,  during a
certain  time, through a tube  into water  holding lime in
solution.  The carbonic acid has the property of uniting
with  this latter substance, and thus  giving  origin to a
body, which is insoluble, and which in its composition is
analogous to chalk; now, in this experiment,  the  car-
bonic acid, which  escapes from our lungs, combines with
the lime, and  forms a whitish powder, which by its de-
position troubles the water, and is easily perceived.  By
such means, in 1757 a chemist, named Black, first proved
the production of  this  gas during respiration.   Carbonic
acid may also be recognised by other  methods, for  it
extinguishes bodies in  combustion, and causes  the de-
struction of animals when  inspired even in small quan-
tities.1

  1 Carbonic acid, which is formed by carbon united in certain proportions
with oxygen, is produced by the combustion of charcoal, during the alco-
holic fermentation, &c, — it enters into the composition of marble, chalk, 
RESPIRATION.
79
   As to the azote of the respired air, its volume    Azote.
changes but little, and its  principal use appears to be to
weaken the action of the  oxygen, which  in the state of
purity excites animals too strongly, and produces in them
a kind of fever.
   It has been remarked, however, that in  some cases, a
part of  the  azote of the air disappeared  during  respira-
tion, and in others, its volume was augmented.   It  would
even appear, that animals absorb and  exhale  it contin-
ually, as they exhale and absorb  the  liquids contained in
the cavity  of the pericardium, peritoneum,  etc., and  that
the variations observed depend upon this ;  that these two
opposite functions  are  in general in equilibrium, so  that
their result is not apparent, but that the absorption being
sometimes more  active than the  exhalation of  the  azote,
while at other times  the quantity exhaled exceeds  that
absorbed, occasions a diminution, or increase  in its vol-


&c, and is found in most mineral waters.  In the state of gas it  is color-
less as air, but much heavier than this fluid, and soluble in water. From
the action of this acid upon the animal economy arises  the asphyxia, pro-
duced by the vapor of charcoal, as well as  most of those accidents, which
take place in  mines, drains, wells, and vaults where wine or beer is fer-
menting.  In a vault  near Naples  it is continually disengaged from the
interior of the earth, and occasions  phenomena, which  at first seem very
singular, and excite the curiosity of all travellers:  when a man enters this
cavern he experiences no difficulty in respiration, but if accompanied by a
dog, the animal soon falls asphyxiated at his feet, and would quickly perish,
if not taken into the fresh air.  This depends upon the fact, that the  car-
bonic acid, being heavier than the air, does not  ascend, but remains near
the ground, and there forms a layer about two feet thick.  Now a dog en-
tering this grotto is necessarily entirely plunged into this mephitic  gas, and
must be asphyxiated ; while a man, whose height is more  elevated, has
only the lower part of his body exposed to the action of the carbonic acid,
and breathes freely the pure air above. This remarkable place is called the
Grotto of the Dog. 
80            ANATOMY AND PHYSIOLOGY.

ume when compared before, or after, it has served for
respiration.
 transphaS   Lastly, there also escapes from the body with
the products of  respiration  a considerable  quantity of
watery vapor.  This  exhalation, which  has received the
name of pulmonary transpiration, is one  of the  most ap-
parent phenomena of respiration,  when  by  the refrige-
rating action of the surrounding air these vapors are con-
densed on their  departure  from the body, and form  a
thick cloud.
 K^biiSS!   While the respired air undergoes the changes
already indicated, the blood, which passes over the mem-
branes in  contact with this fluid, also experiences impor-
tant modifications ; it is  rendered proper for the support
of life, and changes from a  blackish color to a lively and
sparkling  red.   To observe this fact,  we have only to
open an artery in the living animal, and to compress at
the same  time its neck,  so  as  to prevent the  air  from
penetrating into the lungs ;  the blood  flowing  from the
artery will at first be of a lively red, but will  soon be-
come dark, and  of a  venous color.   If  a  new access of
air to the  lungs be then permitted,  this liquid is seen to
change its color, and  take the tint  proper to the arterial
blood.
Jspimtio0^    Such are the principal phenomena of the respi-
ration of  animals.  Let  us  now seek for an explanation
of them.
   And first, what becomes of the  oxygen, which disap-
pears, and what  is the origin of the carbonic acid  pro-
duced during the exercise of this function ?
   When charcoal is burnt in a vase filled with air, oxy-
gen is found to  disappear, and its place to  be supplied 
                     RESPIRATION.                  g|

by an equal  volume of carbonic  acid gas ;  at  the same
time a considerable disengagement of heat takes place.
Now, during respiration, the same phenomena take place,
and a remarkable  relation may always be  observed be-
tween the quantity of oxygen  employed by the animal,
and that of the carbonic acid it produces : under ordinary
circumstances, the volume of the latter is but little below
that  of  the former, and  animals, as will be shown, all
produce more or less heat.
  There exists  then  the greatest analogy between the
principal  phenomena of  respiration, and  those  of the
combustion of charcoal:  and this similarity of result has
given rise to the idea, that the cause  of the two might
be the same.
  And in truth one can hardly  suppose  the respiration of
animals to be other, than the combustion by the oxygen
of the air  of a certain quantity of carbon, furnished by
the bodies of these beings.
  But where-does this combustion  take place ? ^^mm!
Is it the blood, which furnishes  to the air the carbon thus
consumed, and does this combustion take  place  on the
surface  of the  respiratory organ ? or, is  the oxygen ab-
sorbed, and conveyed by the blood into the interior of all
the organs, and the carbonic acid  thus formed in all these
parts, to be afterward expelled by the same way, which
afforded a passage to  the absorbed oxygen ?
  The majority of physiologists have adopted exclusively
one or the  other of these opinions ;  but neither of these
hypotheses is alone sufficient for the explanation of all
the facts observed, and it would  really appear, that the
transformation of oxygen into carbonic acid takes place,
both at  the expense of the blood, at the moment of  con-
                   11 
82           ANATOMY AND PHYSIOLOGY.

tact of this liquid with the air, and in the substance of
the  tissues, which compose our various organs :  the fol-
lowing experiments may be adduced in proof.
   If venous blood be enclosed  in a flask filled with oxy-
gen, and agitated, it  is seen to change its color ; a part
of the oxygen disappears, and  carbonic acid is produced.
All the chemical phenomena of respiration, consequently
take place  independently of life, and  by the  simple fact
of the contact of the blood with the oxygen.  Now in
the  bodies of respiring animals  the  blood is separated
from the air only by very thin  membranes, which do not
at all oppose the contact.   If phosphorus dissolved in oil
be injected into  the veins of a  dog, this substance, when
traversing the capillary vessels  of the lungs, will combine
with the oxygen of the air, burn, and  be driven out as a
thick white smoke.   The blood must then evidently be
submitted  in the respiratory organ to the contact of the
air, and furnish carbon to  the oxygen of  this fluid, as in
the  experiment  previously related;  and consequently it
must be acknowledged, that the  direct combination of
the oxygen of the air with the carbon of the  blood is
the  source, at least  of a  part,  of  the carbonic acid pro-
duced.
   But on the other hand, if an animal capable of resist-
ing asphyxia for some time, a frog, for instance, be  placed
in a vase containing no oxygen, and filled with azote, it
will continue to  exhale  carbonic acid,  as if respiring air.
Now, in  this case, it is impossible to attribute the  forma-
tion of this gas  to the direct combustion already spoken
of, for this  combustion must cease as soon as the respired
air  is deprived of its oxygen ; wherefore the carbonic
acid has simply been exhaled from the respiratory, organ, 
                     RESPIRATION.                  gg

and formed elsewhere, from the oxygen already existing
in the interior of the body of  the animal.
   The vapor, which escapes from  the body at vsa°p'"e4iiede
the same time with the  carbonic acid,  also  arises from
the blood, and is simply exhaled from the surface of the
respiratory organ.  Some  authors think, that  this liquid
is always formed during  respiration, and  that a part of
the oxygen employed, by direct consumption  of the hy-
drogen furnished by the blood, gives origin to  the water;
and thus they imagine that they can explain the cause of
pulmonary transpiration, as well as  the  disappearance of
a volume of oxygen superior to that of the carbonic acid
formed.  But experiment  overthrows this hypothesis, for
pulmonary transpiration continues, when the respired air
no longer  contains oxygen;  and the quantity of vapor
thus exhaled may be augmented at will, by the injection
of water into the veins of a living animal.
   All the volatile substances contained in the  blood, are
also expelled  from  the  body by the exhalation from the
respiratory organ.  If oamphor, or spirit of wine, be in-
jected into the veins of a  dog, they will soon escape with
the vapor issuing from  the lungs, and be  recognised  by
their  odor:  the same result follows  the  injection of hy-
drogen gas in small quantities into the veins.
   We have  elsewhere  seen,  that the same  organs also
absorb with  great  rapidity the matters with which they
are in contact; and this absorption is exercised upon the
gasses, as well as upon the liquids ;  for an example take
the following.
   In  one of the experiments  made upon himself by the
physiologist, Linning, he  found, that his body had  in-
creased in weight eight ounces, without having made use
of any aliment, and solely because he had respired an air 
 84            ANATOMY AND PHYSIOLOGY.

 charged with thick fog.   Now, phenomena analogous to
 those thus accidentally manifested, take place normally in
 the ordinary performance of  respiration.
 Recapitulation.    By a review of what has been said upon the
 nature of the  respiratory function, it is found  to consist
 in these four particulars, viz.:
   1st.  In the direct combustion of a certain quantity of
 the carbon of the blood  by the oxygen of the air;
   2nd. In the absorption of oxygen, and  exhalation of
 carbonic acid ;
   3d.  In the absorption and simultaneous  exhalation of
 a small quantity of azote ;
   4th.  In the exhalation of water furnished by the blood,
 as are  all the other expelled  products.
 tta respiration.  We have  seen, that respiration is  necessary
 for the support of life in all beings ; but the degree of
 activity of this function  varies much in different  animals.
  Birds.     Birds are of all  animated beings the most ac-
 tive in their respiration ;  in  a given time they consume
 more air than  any other  class of animals, and  therefore
 yield more readily to asphyxia.
 Mammifera.  The  mammiferae have also a very active respi-
 ration ; and a great  number of experiments  have  been
 made,  to estimate the  quantity of  oxygen  that one of
 them, man, thus employs in  a given  time.  This quan-
 tity varies with the individual, age, and various other cir-
 cumstances ; but the average appears to be about seven
 hundred and fifty litres or cubic decimetres a day.  Now
oxygen forms  only the twenty  one hundredths  (in  vol-
 ume) of the atmospheric air  ; it  follows  then  that man
consumes, during this space of time, at least three thou-
sand five hundred  litres or cubic decimetres of  the latter
fluid. 
RESPIRATION.
85
   Animals of the inferior classes have, in gene-  Inf„^.a,li
ral, a respiration much more limited, especially those liv-
ing in the water.   But  yet when  we reflect upon the
enormous  quantities of oxygen, that all these beings must
consume daily, it  is  evident that the atmosphere would
soon be deprived of it,  and  all animals perish asphyxia-
ted, if nature did not employ certain means for  the con-
stant renewal of the quantity of this gas, diffused around
the surface of  the globe.
   This she accomplishes by the respiration of influence of
                   1        J       -*         J animals  and
plants ; and it is worthy of observation, that the onThfcompo-
           i    -i        i             r     •  l  sition of the
mean employed  is  a  phenomenon  oi  precisely atmosphere.
the same order with that, whose effects it is intended to
counterbalance.
   Vegetables  absorb the  carbonic  acid diffused in the
atmosphere, and under  the  influence  of the  solar  light
they extract from it the  carbon, and give out  oxygen.
Thus the vegetable kingdom  supplies animals with the
oxygen necessary for  them,  and the  respiration of ani-
mals  constantly furnishes vegetables with the carbonic
acid necessary for their growth.
   We thus see, that  it  is in  a great measure upon the
relation existing between animals  and vegetables, that
the nature of the atmosphere depends ;  and  that in  its
turn the composition of the air must in some sort govern
the relative proportion of these beings.1

  1 From this it might be supposed, that in cities, where a great many men
are collected, and where there are very few plants, the atmosphere must be
less rich in oxygen than in the country, but it is an error.  Chemical anal-
ysis demonstrates that the air has everywhere  the same composition, and
this uniformity must be attributed to the currents, by which the atmosphere
is continually agitated. 
gg            ANATOMY AND PHYSIOLOGY.
  Relation be-   There always exists  a remarkable relation
tween the ac-               J                      1 1      I
rlvt!onir,fthe between the quantity of  air  consumed by each
motion!of   animal in  a given  time, and the vivacity of its
motions.  Animals,  whose  motions  are  slow  and rare,
have, all other things being equal,  a respiration much
less extensive than those which move with rapidity, and
remain but a short time at repose.   A frog, or toad,  for
example, consumes far less air than  certain  butterflies,
although its  body be much larger than that of these  in-
sects ; but these  reptiles move seldom and  slowly, while
the butterflies constantly execute the most lively motions.
 circumstances  The  activity of respiration varies  also in  the
infliiencinslhe                               .
r^irati^n1"6 same animal according to the circumstances,  in
which it is placed;  and it may be established  as a gene-
ral proposition, that everything, which tends to diminish
the energy of the vital movement, determines a diminu-
tion either in the absorption  of the oxygen, or in the rel-
ative  proportion of the carbonic acid exhaled ; while, on
the other hand, <e very thing, which  augments the force of
the  animal,  produces  a corresponding  change in  the
extent of the respiration.
  Thus in the young this function is less extensive than
in the same beings at the adult age.
  During sleep the extent of  respiration  is also dimin-
ished.   Fatigue, abstinence,  the  abuse  of   spirituous
liquors produce the same  effect.   Moderate exercise and
the taking of food exert on this function a contrary influ-
ence.
  Finally, heat augments the  extent of respiration and
cold diminishes it.
  It appears,  that there exist also variations in the quan-
tity of carbonic acid  produced  at  different  parts of  the 
                     RESPIRATION.                   gy

day, and, from some facts, it would seem that the pres-
sure of the barometer exercises a very marked influence
upon this phenomenon.

                APPARATUS OF RESPIRATION.
   Hitherto we have been occupied merely with the phe-
nomena  of  respiration,  considered  in   themselves, and
without regard to the organs, which are the seat of them.
Let us now see what are the instruments of this  impor-
tant function, and how they are modified in different ani-
mals.
   In those with the simplest organization,  respi-   skm,
ration  is not assigned to any special apparatus, but is ef-
fected in all  the parts, which are in contact with the ele-
ment,  in which these beings live, and  from which they
derive the oxygen necessary to their existence.
   The general envelope of the body, or the skin,  is like-
wise the seat of  a respiration more or less active, in the
greater part of animals of the  more elevated classes, and
especially in man;  but in all these beings a  determined
part of  the  tegumentary membrane  is more especially
destined to act upon the  air, and  is so modified in  its
structure, as to better fulfil  this function.
   In the animals, in whom respiration once be-   jf/jf™!
gins to localize itself, it has for its  instrument a  certain
number of membranous appendages,  which are raised
upon the surface of the  skin in some part  of the body,
and assume the form of tubercles, folds, or fringes.
   In other animals, in whom respiration is more  active,
the  portion of the general envelope of the  body to which
is assigned the performance of this act, in  place of rising
upon the surface, folds  inward  and  constitutes  sacs or
canals, into which the air penetrates. 
88            ANATOMY AND PHYSIOLOGY.

 General char-   Whatever  be the form, that the  respiratory
respiratory or- apparatus assumes, it is remarked, that the part
thus modified to act upon the air, presents a soft, spongy,
and fine texture ;  that it  receives a  great  quantity of
blood ;  and that it is arranged so as to offer, under a vol-
ume comparatively small,  an extent  of surface propor-
tioned  to  the activity of  the  respiration.   It may  be
established, as a general proposition, that this organ will
be an instrument  of so  much the  greater power, as  its
organization  differs from that of the general envelope of
the body, and that the respiration, which takes place by
the skin, will be less active in proportion as that by these
special organs is  extended.
 Differences   The structure of the respiratory organs varies,
with regard to                          L     J   u
resePin"tion°f  according as they  are to be in contact with  the
air  in the state of gas, or to  act  upon water  holding in
solution a certain  quantity of this fluid.
   In all animals living under the water, and respiring by
the intervention of this liquid, the special instruments of
respiration are salient, and  bear the name of gills  ; while
in animals with aerial respiration  there are  no gills  but
interior cavities answering the same purposes, and which
are called the lungs, or trachece.
   ghis.   The gills, in their simplest form, consist merely
of a few tubercles with a. texture a little softer than that
of the  rest of the  skin, and which receive  a  slightly in-
creased quantity  of blood; but they are very far from
being the sole instruments of respiration, and  the  rest of
the skin takes an  active  part in its performance.
   Several marine worms possess this mode of organiza-
tion ; but when these organs are to be the seat of a more
active  respiration, their structure is complicated, and they 
RESPIRATION.                  89
take the form of lamellae very thin  and numerous, or of
simple,  or ramified membranous filaments.
  The former of these modes of structure is met with in
most  of those animals, which, with the crabs and lob-
sters, constitute the group to which the name of Crustacea
has been given, and in a great number of those inhabit-
ing the  interior of shells, and which constitute the class
mollu«ca ;  oysters,  for example.   The  second modifica-
tion of  the gills is found in fishes, &c.
  The interior cavities, which serve for the  aerial  respi-
ration, sometimes take the form of trachea1, sometimes of
lungs.
   The  trache.-e are vessels,  which communicate  Trachea-.
with  the exterior by openings called  stigmata, and ramify
in  the  interior of the  various organs.   They convey to
them the air, and consequently respiration is effected in
all  parts of the body.    This  mode of structure is peculiar
to insects and some of  the arachnidae.
   The  lungs are sacs more  or less divided into   i^ngs.
cellules, which receive  the air into their interior, and the
walls of which are traversed by the  vessels containing
the blood to be  submitted to the vivifying  influence of
the oxygen.
   Lungs exist (but  in a state  of great simplicity,) in
most spiders, in some of the mollusca, such as snails.
Reptiles, birds,  and  the mammiferse, are also provided
with them.
    In man, (as well as  in all the mammiferse,) iungsof man.
the lungs are lodged in the cavity called the thorax, which
occupies the superior  part  of the trunk, and  which is
separated  from  the abdomen (or belly) by  a transverse
partition, formed by  the diaphragm.  These organs are,
                   12 
90
ANATOMY AND PHYSIOLOGY.
so to speak, suspended  in this cavity, and are enveloped
by a thin, close membrane, which  also  lines the thorax,
and  which is  called the pleura.1   They are in number
two, one upon either side of the body, and they commu-
nicate externally by means of a tube, the trachea, which
ascends along  the  anterior part of the  neck, and opens
into the posterior fauces.
Fig.  16.
     This duct is formed by a se-
  ries of small cartilaginous bands
  placed across, in the form of in-
  complete rings :  their  interior is
  lined by a  mucous membrane of
  the same nature with that of the
  mouth, and continuous with  it.
  Finally, at its inferior part  the
  trachea divides into two branches,
  which take the name of bronchi,
d and which  ramify into the inte-
  rior of each lung, as the roots of
  a tree in the soil.
     The lungs, as  we have already
  1 The disposition of the pleura is analogous to that of the other serous
membranes, of which we have spoken (page 71).  It forms a sac without
opening, which is folded upon itself, and the external half of which adheres
to the walls of the thorax, while the other half is fixed upon the surface of
the corresponding lung: the internal face  of the pleura is consequently
every where in contact with itself, and as it is extremely smooth, and con-
tinually lubricated by serosity, it slides very readily, and essentially favors
the respiratory motions.
  2 This figure represents the trachea and the lungs; one of these organs
has been left untouched (d), but on the other side the substance has been
destroyed  to expose the ramifications of the bronchi  (e).  a, Larynx and
superior extremity of the trachea; — b, trachea; — c, divisions of the bron-
chi ; — e, bronchial twigs; — d, one of the lungs. 
                     RESPIRATION.                  gj

said, present in their interior a multitude of cellules, into
each of which a small branch of the corresponding bron-
chus opens.  The walls of  these  cavities are formed by
a very fine, soft membrane, pierced by numerous capillary
vessels, which receive the venous blood coming from the
pulmonary artery, and expose it  to the action of the air.
  Within the same volume, the smaller the size of the
cellules of which the lungs  are formed, the greater is the
surface,  upon which respiration will act, and the more
numerous are the points where the  blood comes in con-
tact with the air.   There  consequently exists a  direct
relation between the size of the  pulmonary cellules, and
the activity of the respiration ; for  example  in frogs, in
whom this function is exercised only in a slow and feeble
manner, the  lungs have the form of sacs, merely divided
by  a few partitions;  while  in  the mammiferae and birds,
in whom respiration is most active, these organs are di-
vided  into cellules so small, that by the naked eye it is
difficult to perceive them.
  In man and the other mammiferae, the bronchi all ter-
minate in the pulmonary cellules, and these  latter  are
always terminated in a cul-de-sac; wherefore  the  air,
which enters the lungs of these animals, can advance no
farther.   But in birds, in whom  respiration is yet more
active, some of these canals  traverse the lungs completely,
and open into the cellular tissue which surrounds  them,
and which in the  rest of the body fills the spaces between
the different organs;  the cavities contained  in this tissue
all  communicate together, and the  air, which arrives in
them also penetrates  into all parts of the body, even into
the substance of  the  bones. 
92
ANATOMY AND PHYSIOLOGY.
               MECHANISM OF RESPIRATION.
  From what has been said of the alterations, which the
air  undergoes from respiration,  it is evident, that  this
fluid must be unceasingly renewed in the interior of the
lungs ; which is effected  by the movements of inspiration
and expiration, that we momentarily execute.
  The mechanism, by which  the  air is  drawn into the
lungs, or expelled from them, is very simple, and resem-
bles in all  points the play of  a  bellows, except that in
the former  the fluid penetrates into and escapes from the
organ by the same outlet.   The  walls  of  the thorax
being movable, its cavity may  be alternately enlarged
and contracted, and the lungs  will follow all their move-
ments ;  thus in inspiration, the column of air pressed by
the whole weight  of the atmosphere, is  driven into the
chest through  the  mouth, nasal  fossae, and trachea, and
fills the  pulmonary cellules, in the same  way  that water
ascends in the body of  the  pump  when the piston is
raised.  In expiration, the air contained  in the lungs is,
on the contrary, compressed and driven out by the  same
way,  which served for its entry.
  To understand  how  the thorax of man dilates and
contracts, it is necessary  to examine  its structure. 
RESPIRATION.
93
Structure of
the thorax.
             Fig. 17:                 This  cavity
                  ?          ?       has the  form  of a cone
                                   with the apex above and
                                   base below, and its walls
                                   are chiefly formed by a
                                   kind  of  bony  cage,  re-
                                   sulting from the union of
                                   the ribs  with  a  portion
                                   of the vertebral  column
                                   (or spine,) behind, and
                                   with  the os sternum in
                                   front.
                                      The spaces between
                                   the  ribs  are  filled  by
                                   muscles,  which  extend
                                   from one of these bones
to the other; muscles also pass  from  the first  rib to the
cervical  portion of the vertebral  column ;  lastly, the in-
ferior wall of  the chest  is  formed  by the diaphragm,
which is attached  to the inferior border of the  bony case
just mentioned.
   The dilatation of the thorax may take place ™KiSIut?f
in  two  ways, by  the  contraction of  the  diaphragm, or
elevation of the ribs.
  1  Thorax of a man.  The muscles of the left side are removed, those on
the right entire.
  a, Cervical portion of the vertebral column ; — a\ lumbar portion of the
column ; the dorsal portion, which enters into the formation of the thorax
is concealed by the sternum, &c.; — b, sternum ; — c, c, ribs; — c', false
ribs; — d, clavicle; — e, intercostal muscles; —/, lower false rib, concealed
by the insertion of the diaphragm ; — g, arch formed in the interior of the
thorax by the diaphragm ; on the right side the continuation of this arch
is indicated by the dotted line; — h, pillars of the diaphragm inserted into
the  lumbar vertebrae; — i, levator muscles of the ribs. 
94
ANATOMY AND PHYSIOLOGY.
^3^   The diaphragm in  the  state of repose forms
an elevated arch, which  ascends into the  interior of the
chest (g) ; and it is easy to perceive, that the contrac-
tion of this muscle  must diminish the curvature of the
arch, and thus proportionately enlarge  the cavity of the
thorax.
  The  action  of the ribs  is a little more complicated ;
these bones, (c and c') to the number of twelve on a side,
describe each a curve, the convexity of which is  turned
outwards  and a little downwards;  their anterior extrem-
ity, which is united  to the sternum (6) by means of in-
tervening cartilages, is much less elevated than the pos-
terior, and the  articulation of the latter with the vertebral
column, permits them to ascend and descend.  The for-
mer of these motions is determined by the contraction of
the muscles at  the base of the neck, (i.)   When the ribs
ascend, their tendency is to form  a horizontal  line; for
at the same time that  their anterior extremity ascends,
carrying  with  it the  sternum, they turn a  little  upon
their axis, so that their curve is no longer directed down-
ward,  but outward; wherefore the lateral and  anterior
walls of the thorax are  removed  to  a greater distance
from the vertebral column, and the capacity of the chesi
increased.
 expiation!    In the movement of expiration the diaphragm
is relaxed, and  the lungs, by reason of the elasticity of
their tissue, contract, and draw with them this muscular
partition,  till it ascends like an arch.  When the muscles,
which have produced the elevation of the  ribs and  ster-
num, cease to contract, the weight of these  bones,  and
the traction made by the elasticity of the  lungs  causes
their depression; but there are also other forces, which 
RESPIRATION.
95
may contribute to the diminution  of  the  capacity of the
thorax, and the expulsion of the air from the lungs : such
are the contractions of the muscles, which form the walls
of the  abdomen, and which are fixed to the  inferior part
of the  chest.
   Several degrees  may be remarked in the  ex-  S^SS..0*
tent of these movements, and in ordinary respiration, the
quantity of air aspired by the thorax, or driven from the
lungs,  scarcely exceeds the seventh part of what these
organs can contain.   The quantity of air, contained in
the lungs under ordinary circumstances, has been estima-
ted  at nearly 4580 cubic centimetres,  and that which
enters the chest, or issues from it,  at each inspiration, or
expiration, at 655 cubic centimetres.
   The number  of the  respirations varies with Frequency
                           1                   of the respira-
the individual and the age ;  in infancy they are tions-
more frequent than in the adult, and in the latter there
are about twenty inspirations to the minute.
   Thus we  see, that in the ordinary state there must
enter the lungs of a man about 13,100 cubic centimetres
of air in a minute, making about 786 litres to the hour,
and the  daily consumption  nearly 19,000 litres  of this
fluid.
   Sighing, gaping, laughing, and sobbing, are Modifications
but modifications of the ordinary movements 0florymotions-
respiration.  Sighing is  a  long and deep inspiration, in
which a great quantity of air gradually enters  the lungs ;
thus this phenomenon does  not depend  solely upon the
moral  affections, which are its most frequent cause, but
the need of sighing is felt whenever the respiratory func-
tion is not effected with sufficient rapidity.
   Gaping is an inspiration  yet deeper,  accompanied  by 
96
ANATOMY AND PHYSIOLOGY.
an almost involuntary and spasmodic contraction  of  the
muscles of the jaw and velum palati.
  Laughing consists in a succession of slight interrupted
expiratory motions, varying in frequency, and chiefly  de-
pendent  upon  the almost convulsive contractions  of  the
diaphragm.   The  mechanism of sobbing differs -but little
from  that of  laughing,  although the former expresses
very different affections of the mind.

  THE INFLUENCE OF  RESPIRATION  UPON THE OTHER FUNCTIONS.
  In concluding our remarks upon  respiration, we will
add a few words upon  the influence  of its various  move-
ments on the other functions, the history of which  has
already been given.
 Son1!6 cir"   ^ is evident, that  the dilatation  of the  thorax
must produce upon the blood, contained in the great ves-
sels emptying into this cavity, the same  effect as upon
the air contained in the trachea.  By the movements of
inspiration, that portion of  the  venae cavae, comprised
within the thoracic  cavity, is swollen by  the access of
blood thus aspired ; and from the same  cause the veins,
which enter this cavity, but are situated  externally, and
consequently under the influence of atmospheric pressure,
are more or less completely emptied.
  This  kind of suction contributes to aid the course of
the blood in the venous system, and  is felt even  in  the
arteries,  with  which  the former vessels  are  continuous
through the intervention of the capillaries.
  The motions of  expiration, on  the contrary, momenta-
rily suspend the course of the blood in  the great veins,
and accelerate it in the arteries, which originate from the
heart, and are thus compressed. 
                     RESPIRATION.                    97

   To these two phenomena must be attributed the swell-
ing of the veins, (especially those of the head and neck),
during expiration.  In the interior of  the  cranium  this
swelling is so marked, that at each respiratory movement
the vessels, situated at the base of  the brain,  elevate  this
viscus, and produce a kind of pulsation.
   The  dilatation  of  the chest appears also  to vsp™tk!n.ab"
exercise a remarkable influence upon the absorption  ; in
fact  it  acts  like a pump upon all which surrounds the
thorax,  and must tend to force from without inwards, all
the fluids which communicate with its  interior ;  but  this
action is felt  only in the immediate neighborhood of the
chest.
   Finally,  the abundant  exhalation, which al- upon the Pui-
        ■'                                     monary exha-
ways takes place upon the  surface of the  pul- Iation-
monary cellules, is  determined in a great measure by the
degree of suction, which accompanies each movement of
inspiration, and which  acts  upon  the  liquids, by which
the walls of these cellules are moistened, as it acts upon
the blood of  the venae cava?, and primarily upon the air
of the trachea.  We have already seen, that in the nor-
mal  state,  all  the  volatile  substances  met with  in  the
blood are thus exhaled ;  but if the thorax of a living ani-
mal  be  opened, and  artificial  respiration  performed, so
that there is no suction upon the surface of  the pulmo-
nary cellules, this exhalation is almost entirely arrested ;
and then camphor injected into the veins does not escape
more rapidly  in this way, than from the surface of  every
other membrane, whose tissue is as vascular and permea-
ble to liquids.
                  13 
98
ANATOMY AND PHYSIOLOGY.
                   ANIMAL  HEAT.

  There exists another phenomenon, the history of which
is closely united to that of the respiration, and  the  im-
portance of which is so great that we must  necessarily
devote some time to it, viz. : the faculty of producing heat.
 Difference    This faculty appears to be common to all ani-
in the temper-             J  >■ *-
atnre of ani- ma]s. j^ tne majority develop so little caloric,
that it cannot be appreciated  by our ordinary thermome-
ters ;  while in the remainder  the production of heat is so
great, that we are not required to make use of  scientific
instruments to prove its existence.   To compare this dif-
ference, we have only to place a hare and a fish, having
about the same volume, in two calorimeters, and to sur-
round  them with ice at the temperature of  0° ;  the
quantity of this body melted in a given time will be pro-
portional to the quantity of heat developed by these two
animals.  Now, in  the instrument containing   the fish,
the quantity of ice  melted in the  space  of three hours,
for example, will not be appreciable ; while in that con-
taining the hare, we shall find, after  the  same  lapse of
time,  more than a pound of liquid water; and to  melt
this quantity of ice  would require as much heat, as to
warm  from melting ice  to  boiling water about three
fourths of this weight of water; this heat could only have
been furnished by the animal under experiment.
  This enormous  difference  in the production  of heat
occasions corresponding differences  in the  temperature of
the different  animals.   A thermometer  placed in  the
body  of a dog or bird, for example,  will always  ascend to
36 or 40 degrees, (centigrade,) while in the body of a 
                     ANIMAL HEAT.                 gg

frog or fish, it will indicate  a temperature  nearly equal
to the atmosphere at the time of the experiment.
   These  are  called animals with  cold blood, which do
not produce a sufficient degree of heat, to  have a tem-
perature of their own and independent of the atmospheric
variations;  those  are  animals ivith warm  blood, which
preserve a temperature nearly constant through the ordi-
nary variations of heat and  cold,  to which they are  ex-
posed.  Birds and mammiferae are  the only beings inclu-
ded in the latter class ; all others  are animals with  cold
blood.
   The  temperature  of man and  most of  the  Temperature
            J-                                  of the mammi-
other mammiferae scarcely varies from 36 to 40 fer!E and birds'
degrees ;  that of birds ascends to about 42  degrees,, cen-
tigrade.
   But  the faculty of  producing heat varies in "nS!"8
the different animals of these two classes, and also in the
same individual,  according to age  and circumstances.
Thus most mammiferae and birds produce a sufficient de-
gree of heat, to preserve the same  temperature in sum-
mer and winter, and  to resist the ordinary effects of cold,
though it be very severe.  But there are  others, which
produce only heat enough to raise  their temperature  12
or 15 degrees above that of  the atmosphere ; wherefore,
during  summer,  their temperature  is nearly the same
with the warm-blooded animals, but in the  cold season it
is much diminished ; and whenever  this  cold reaches a
certain limit, the vital movement is rendered slower,  and
the animal experiencing it falls into a state of  torpor, or
lethargic  sleep, which lasts till the temperature again as-
cends.   The beings,  which present this  singular  phe-
nomenon, are called hibernating animals, and in this re- 
100           ANATOMY AND PHYSIOLOGY.
spect they are in some  sort intermediate  between  the
warm-blooded animals non-hibernating, and the  animals
with cold blood.
 influence of   In the early periods of life, all warm-blooded
age upon the             J -1
production *>f animals are more or less  nearly  allied  to  the
cold; these, as well as the latter, do not produce in gen-
eral sufficient heat  to  preserve  their  temperature, even
when exposed to very slight  degrees  of  cold.   But  the
decrease of temperature, which  is without inconvenience
for the cold-blooded animals, acts  upon  the others in  a
very different manner, for always,  if carried  beyond  a
certain degree, or lasting a determined  period, death is
the result.  With regard to the faculty of producing heat,
the young of warm-blooded animals, which are born with
their eyes open, and which immediately after  birth  can
run and seek their nourishment, differ far less from  the
adults, than the mammiferae,  which  are  born  with their
eyes closed, or  birds, which on issuing from the egg, are
not yet  covered with feathers.   If,  for example, new
born cats and dogs  are taken away from the parent,  and
exposed to the  air, even  in summer, they are  chilled to
the very  point of death.
   Infants produce also much  less heat in the  first days
following birth, than at a more advanced  period of their
life ; their temperature then  decreases very readily,  and
the influence of cold is very injurious to them ;  therefore
a greater number die in winter than during the  rest of
the year.
   Everything, which acts as  an excitant and which aug-
ments the energy of the vital movement, tends also to
augment the faculty of producing heat, and everything,
which weakens the animal economy, exercises  a  debili-
tating influence upon this function. 
                   ANIMAL  HEAT.                  iqi

  Thus the action of a moderate cold tends to fllIn,fluence »r
                                             tne temperature.
augment  the  faculty of producing  heat,  and in conse-
quence during winter we can better resist the causes of
chill than in summer.
  The  influence of heat, when  not prolonged  for too
long a period,  is excitant and increases  the faculty of
producing caloric; but, if long continued, it weakens the
body and diminishes the energy of this faculty.   For this
reason, persons, who have resided for some time in tropi-
cal  regions, are so sensible to the cold of our winters.
  Finally, exercise ever augments the produc- exerdse,ce&c!
tion of heat, and the acceleration of the respiratory move-
ments is followed by the same effect.  During sleep, this
faculty appears to be,  on the contrary, less powerful than
when awake; thus when men,  exposed  to  a very low
temperature, have  the imprudence  to fall asleep,  they
yield to its effects  more rapidly than if awake  and in
motion.   The  disastrous retreat  from  Russia furnishes
numerous examples of the bad effects of sleep upon the
soldiers, weakened by fatigue and privation of all kinds,
and exposed to a most intense cold.
  The cause of the production of heat in the  cause of the
                                              production  of
body of animals appears to be the action of the heat-
arterial blood upon the tissues, under the influence of the
nervous system.  There  exists an  evident relation be-
tween the faculty of producing heat,  the intensity of the
nervous action, the richness of the blood,  and the more
or less rapid transformation of the venous to arterial blood.
  Experiment has  proved,  that every thine:,  influence of
   .             .                    J     ®  the nervous
which tends considerably to weaken  the action system-
of the nervous system, tends also to diminish the produc-
tion of heat.  Thus if the brain  or  spinal marrow of  a 
102
ANATOMY AND PHYSIOLOGY.
dog be destroyed, and the respiration be imitated by ar-
tificial means, the life of the animal is indeed  sustained,
but the production of heat ceases, and the body becomes
cold as rapidly as  a dead body would  do, if placed  in
similar  circumstances.  If  the  action  of the brain  be
paralyzed by  certain energetic  poisons, such as opium,
the same effect is produced, and these experiments varied
in different  ways have firmly established  the  fact, that
one of the  conditions necessary to the development  of
animal heat is, the  influence exercised by the  nervous
system upon the rest of the body.
 ^eK/   °n the  other  hand, the action of  the  blood
upon  the  organs appears to be equally indispensable  to
the manifestation of this  phenomenon ;  for, the  suspen-
sion of its circulation in any part of the  body is followed
by  coldness of the  part;  and,  moreover, a remarkable
relation exists  between the faculty of producing heat  in
different animals, and the richness of their blood.   Birds,
which have the highest temperature of all animals, are
also those whose blood is the most loaded with solid par-
ticles  (in general fourteen or fifteen parts to the hundred) ;
the mammiferae, whose temperature is  not quite so ele-
vated, have  more aqueous blood, in  general the weight  of
the globules constituting  only the  nine  or twelve hun-
dredths of the  total weight of this  liquid ; lastly, in the
cold-blooded animals, such  as frogs and  fishes, we find
barely six parts of globules and  ninety-four of  serum.
thSra'uonf   But the action of the nervous system, and  of
a blood more or less rich in globules, are not the only
circumstances, which influence the  production of animal
heat; in order that the nutritive  liquid may exercise upon
the economy the necessary action, it must possess all the 
                   ANIMAL HEAT.                  jqo

properties, which characterize the arterial blood ; and as
it acquires these only from respiration, the development
of caloric must  also  depend  upon this latter function.
All the causes, which render the transformation from ve-
nous to arterial  blood less complete, or less rapid, tend
also to diminish the  production of the heat,  and there
always exists an intimate relation between it and the
activity of the respiration.
   The formation of cabonic  acid,  which  is one of the
most remarkable phenomena of the respiration  of  ani-
mals, may also explain to us the cause of the  production
of the greater part of the heat developed by these beings.
If the oxygen absorbed during respiration is employed to
form this gas  by its union  with the carbon, arising from
the  blood or  from  the living tissues, as we have every
reason to suppose, this combination must be accompanied
by a disengagement of heat as from the  combustion of
charcoal  in the air.
   Numerous  experiments,  made with an extreme preci-
sion, demonstrate that  the heat,  which would be  pro-
duced by the combustion of the carbon contained in the
carbonic  acid gas exhaled by warm-blooded  animals, is
equal to  more than  half the quantity of caloric disengaged
by these beings.   And  if we admit, that the absorbed
oxygen,  without being  replaced by the carbonic  acid,
combines in the interior of the body with the hydrogen
to form  water,  we see,  that the heat produced  by  this
combustion taken with  that  of  the carbon already men-
tioned, would be equivalent to nine tenths  of that devel-
oped by  the animal.  The motion of the blood, and the
friction of the different parts of the  body probably  pro-
duce the remainder. 
104
ANATOMY AND PHYSIOLOGY.
   As a last analysis we see then, that the respiration is
 the  principal  cause  of the  production of  animal  heat;
 and that the kind of combustion, occasioned by the ac-
 tion of  the oxygen upon  the blood and living organs, is
 effected solely through the influence of the nervous sys-
 tem.
 ofThTdPirTearente   This important function is not, however, ex-
 uody.      ercised with  the same  energy in  all parts of
 the  body; those,  in which the blood  circulates,  with
 greater  abundance and rapidity (and  in  which,  conse-
 quently, life is the most active), are also those, in which
 the most heat is  disengaged ;  and therefore the organs
 more distant from the heart, must, cceteris paribus, produce
less  heat,  and  consequently  be  more readily chilled.
This is the true  state of the  case ;  the temperature of
our limbs  being less elevated than that of the trunk, if
we are exposed to the action  of an  intense cold, these
parts are the first to freeze.
 s^ung heat   The faculty of producing heat explains to us,
why animals with warm blood have a temperature, which
can sustain  itself above that of the  surrounding atmos-
phere.  But how happens it, that these beings can pre-
serve the same temperature, when they are placed  in air
hotter than their body ?   A man, for example, can re-
main during a certain time in a dry hot-house, where the
air is heated to a degree  approximating boiling  water,
without any perceptible increase of the temperature  of
his body except two or three degrees.
  The  power of thus resisting  heat depends  upon the
evaporation of water, constantly going on at  the surface 
                       DIGESTION.                    jQ£
of the skin, or in the apparatus of  respiration, and which
constitutes the  cutaneous and pulmonary transpiration;
for the  transformation  of water into  vapor,  withdraws
caloric from every thing surrounding it, and  the body is
chilled as fast as warmed by the external heat.   For the
same reason water placed in the porous vases, called alcar-
azas, cools so promptly  even in mid-summer.1   Now the
quantity of water thus evaporated, increases with the tem-
perature of the  air, and  the  cause for the cooling becomes
more powerful,  the greater  the heat of the atmosphere.
                      DIGESTION.

   We have already seen, that all living beings are obliged
continually to  seek in the  exterior world for  nutritious
substances, and to assimilate to  their  organs new mate-
rials.   We have also seen how this absorption is effected,
and the study of respiration affords us examples of these
substances thus penetrating into  the nutritive liquid, and
being carried by it into the interior of the organs, with-
out having undergone any previous modification.
   In  vegetables,  all  nutritive  substances  penetrate  di-
rectly  into the organs.  But, in animals, the  greater part
of the materials necessary for the support of  life, are  not

  1 These vases allow the water they contain to filter through, and  thus
have a constantly  moist surface, from which a  rapid evaporation takes
place, which cools  the liquid contained in their interior.  From the same
cause, do we experience so lively a sensation of cold, when ether is poured
upon the skin, and the part thus moistened blown upon.
                    14 
106
ANATOMY AND PHYSIOLOGY.
absorbed until they have undergone a certain preparation,
by means  of which  their properties  are  changed, and
their  composition modified ;  or, in other words, till after
they have been digested.
  Aliments.    The  name of aliments may be given  to  all
substances, which, introduced into the body of a  living
being, serve for its increase, or to repair the losses it con-
stantly undergoes ;  but in general, the sense of this word
is  more restricted, and  is only applied to the materials
which are not absorbed,  and  may not serve for nutrition,
till after they have been digested.  For the sake of per-
spicuity, we  shall only employ it in  the  latter accepta-
tion.
depFendnin™eunpa   Aliments are not  less  necessary to life, than
aliments?0 ° the  air  we  breathe, or the water  which our
body  continually absorbs, either in the  liquid state  as
drink, or in the form  of vapor.   When animals  are de-
prived of them,  their body  diminishes in  volume, their
powers  are weakened, and death arrives after sufferings
more  or less prolonged.
 Hunger.   The want of aliments first makes itself known
by a peculiar sensation, which has its seat in the stomach,
hunger.  It is increased  by  exercise, by the stimulating
influence of a moderate cold, and by the action of cer-
tain bitter  substances, as the cashew nut, upon  the sto-
mach.  On the contrary, everything, which retards the
vital  movement,  immobility, sleep,  &c,  also tends  to
render this want less imperious.   Hibernating  animals
take  no  food during the season of  their lethargy, and
cold-blooded  animals, such as fishes  and frogs, can sup-
port a very long  abstinence,  when the exercise  of their
functions is retarded by the influence of a very low tern- 
                      digestion.                  107

perature.   But the animals, whose nutritive movement is
very rapid, such as man and most mammiferae, soon perish
for the want of food.  The herbivorous, whose blood is
less rich in globules  than the carnivorous, yield  sooner
than the latter ;  and young animals, whose  nutrition is
much more active than  in the adult (since the volume of
their  body is constantly  increasing,  in the place of re-
maining stationary), also  die of  hunger sooner  than the
latter.   Dante, in the famous episode of Count Ugolino,
has but depicted  in  lively colors the  truth,  as  it would
occur, if a man, already having reached  the period of
his growth, and children of a tender  age, should  at the
same time  be deprived of all nutrition.
  Prolonged abstinence occasions very remarka-  "^nuton."1
ble phenomena, which may be ranked under three heads.
In the  first  period,  hunger makes itself frequently felt,
and occasions a greater or less degree of weakness, with
considerable alteration  of the features.  In  the  second
period,  the intellectual faculties  are troubled ; in man, as
well as in  animals,  inquietude, or even fury arises, and
sometimes  mental  alienation is manifested  by visions.
Lastly, in  the third  period, this  exaltation gives place to
a state  of  depression or complete stupidity, and it  is to
be observed, that often when abstinence has  been pro-
longed beyond a  certain period,  the  use of aliments can
no longer  save the life of the individual.   In this latter
case death almost  always ensues, whether the  animal
continue to fast, or retake its ordinary regimen.
  The  aliments are all furnished by the organic  Nature  and
                                 J      °     properties  of
kingdom, and life is maintained  in man and alP"ealimen,s-
other animals from  substances,  which have  themselves
made part  of a living being. 
108
ANATOMY AND PHYSIOLOGY.
   All alimentary substances  do not  possess the nutritive
property in the same  degree,  and very curious experi-
ments have established  the fact, that in  most animals at
least, the union  of a  certain  number of different  sub-
stances is indispensable to the wants of life.   Thus hares,
nourished upon a single substance, such  as  cheese,  cab-
bages, oats, or carrots, die in the  space  of  about fifteen
days, with all the appearance of inanition, while if nour-
ished with these same  substances,  given together, or suc-
cessively at short intervals, they live  and do well.
   The diversity and multiplicity of the aliments, is  then
an important  rule of hygiene ;  and in this, the precepts
of science agree perfectly with our instinct, and with the
variation, brought by the  seasons  in the alimentary sub-
stances offered us by nature.
   Experiment has also proved, that substances, such as
sugar, gum, oil, and fat, into the composition of which no
azote enters,  cannot suffice for the nutrition of animals,
in whatsoever order they may  be  given.   The use  of a
certain quantity  of azoted aliments, such  as muscular
flesh, the gluten  found in the  grain, albumen, &c., ap-
pears to be indispensable to the support of the life of all
animals.
   When we compare the nutritious qualities of the differ-
ent alimentary substances, we must also take into  con-
sideration the quantity of water they  contain ;  by deduct-
ing this from  the  weight of the mass  employed, we arrive
at the knowledge of the really  nutritious matter.  Thus
our ordinary  bread contains, to the  1000 parts, 250 of
water;  beef  about 700; potatoes  750;  turnips  and
cabbages 950.
   But  the different  substances,  which  may serve  as 
                      DIGESTION.                   j 09

aliments to animals, vary with the nature of these beings;
and these differences, as we shall see, are always in rela-
tion to other differences in the organization.   From an
investigation of the digestive  apparatus, we can under-
stand why one animal is nourished upon vegetables, and
another upon flesh.  But one thing, for which we cannot
account, but which is  notwithstanding very true, is the
faculty  possessed  by certain animals of nutrition  upon
substances, which, to others, are violent poisons.   Thus,
goats and sheep may eat with impunity hemlock, while
a very small quantity of this plant is sufficient to destroy
man and many other animals.
   Digestion, or the process by which animals  Modification
     n      \       r         J                of the aliments
modify the aliments so as to render them properby disestion-
for absorption  and  nutrition,  consists  essentially in  the
action of certain  humors upon these matters, in conse-
quence  of which  they undergo various alterations, and
are separated  into two parts ;  one destined to penetrate
the interior of the  body, and supply  the  wants of  the
animal, called chyle, the other  improper for this  purpose,
and ultimately expelled  under the form of fasces.
   From the nature of  this process, it is evident,  seat of the
                          ■"•                   digestive pro-
that digestion must always take place in an in- cess-
terior cavity of the body, which may serve as a reservoir
for these humors, and for  the  aliments they are to  act
upon.   All animals are provided with a digestive cavity,
and the  existence of this organ is one of  the characters
distinguishing them from vegetables, in which the alimen-
tary substances are absorbed  without  any previous pre-
paration.
   In some animals with very simple structure, this sac is
but a fold of the  skin which penetrates deeply into the 
110
ANATOMY AND PHYSIOLOGY.
body,  and terminates in a  cul-de-sac.   This is the case
with the hydrae or fresh water polypi, of which we have
already spoken :  thus one of these animals can be turned
like the finger of  a glove, without changing its manner of
living.   The surface, which was exterior, then becomes
interior and  forms the cavity, in which  the aliments are
digested, while the  surface which originally  lined  this
cavity, becomes  external, and no longer acts upon these
substances.
apparatus!   The digestive ca-
vity of man and most an-
imals  has  the  form  of
a  long canal, extending
from one extremity of the
trunk  to  the other,  with
alternate  dilatations and
contractions, so as to con- m
stitute  several  kinds  of
chambers or pockets, uni-
ted by ducts more or less 8
narrow.    This  tube  is
formed by a  membrane,
called  mucous, analogous
in structure  to the  skin,
with which it is  continu-
ous ; differing however in
its greater degree of soft-
  1 Digestive canal and its appendages.
  a, iEsophagus, — b, stomach, — c, pylorus continuing with the duode-
num, or first portion of the small intestine, — d, d, small  intestine, — e,
caecum, or first portion of the large intestine, in  which the small intestine
terminates,—/, vermiform appendix of the coecum, — g, ascending colon, 
                       DIGESTION.                   ] ] 1

ness, the greater number of its capillary vessels and se-
cretory follicles, and in the almost complete absence of epi-
dermis.   Surrounding this membrane is a fleshy envelope,
formed of muscular fibres, somewhat abundant, and by their
contractions driving the alimentary substances from the
mouth to the anus, or arresting them in their course, and
impeding their progress for a certain  time in one, or anoth-
er part  of the digestive apparatus.   Lastly, in a great part
of its  extent,  this tube  is  also  enveloped  by a  serous
membrane, thin, and  transparent, called the peritoneum,
which  serves both  to  fix it, and to facilitate its move-
ments.
   The digestive apparatus is  composed of  this alimen-
tary tube, of the organs destined to divide the aliments,
of the various glands  serving to form the humors neces-
sary for digestion ; and of  the vessels  charged with  the
duty of conveying the nutritive materials thus elaborated,
from the digestive cavity into the interior of the appara-
tus of circulation.
   The  alimentary tube takes, in various parts, different
names.    Its anterior part, enlarged,  and filling the  pur-
pose of a sort of vestibule, is called  the mouth, the cavity
continuous with  it is called the pharynx;  the third  part
of the canal constitutes  the cesophagus;  the fourth the
stomach; the fifth the small, and the sixth the  large  in-
testines, which terminate  at  the anus.
   In  man,  and  the animals  nearly allied to him,  the
organs which effect the  mechanical  division  of the ali-
ments, are situated in the mouth, and are called the teeth.

— h, transverse colon, — i, descending colon,—j, rectum, — k, extremity
of the rectum, — I, liver, — m, gall bladder, —n, pancreas, a great portion
of this gland is concealed behind the stomach, — o, spleen. 
112
ANATOMY AND PHYSIOLOGY.
But in certain animals this process is confided to other
parts, to the stomach, for example, as in birds.
   The principal glands of the digestive apparatus are ;
the  salivary glands, the gastric follicles,  the  liver,  and
pancreas.
   Lastly, the vessels which serve for the absorption of
the products of digestion, are in man, as well as all other
mammiferae, birds,  reptiles, and fishes,  special  canals
called chyliferous, or lacteal vessels.
   All these organs, with the exception of the mouth, sal-
ivary glands, pharynx, and aesophagus, are  lodged in a
large cavity, which occupies the inferior two  thirds of the
trunk,  and is called the abdomen, or belly.   It is  separa-
ted  from the thorax  by the diaphragm, and terminated
inferiorly by a basin, formed of a large bony circle, the
centre of which  is  occupied  by a kind of fleshy wall.
Behind,  it  is bounded by the spine, and in front, as upon
the sides,  its walls  are  formed by large muscles, which
extend  from the  thorax to the basin, (pelvis,) of which
we have just spoken.  The internal surface of this cavity
is lined by the peritoneum, and this membrane moreover
forms various turns,  between the folds of which are con-
tained the stomach, intestines, liver, pancreas, and spleen.
These folds, called mesenteries,  all  originate from the
posterior part of the  abdomen, and some among them are
prolonged much beyond  the organ they are to cover, and
thus form veils or aprons called  epiploons.
  to?^2t$!    The  introduction  of the aliments into the
digestive canal is effected in various ways ;  and its  me-
chanism  is varied according as the substances  are liquid,
or solid ; but it is always performed  either by the move-
ments  of the mouth, or by means of the  superior extrem-
ities. 
                      DIGESTION.     ,               ,jq

   With anatomists, the mouth does  not  consist  Mouth.
 in the opening which separates the two  lips, but in the
 oval cavity, formed above by the upper jaw and palate,
 below  by the tongue and  lower jaw,  laterally by the
 cheeks,  behind by the velum palati,  and  in front by the
 lips.   Its  external  communication may  be enlarged or
 closed at will, either by the  movement of the lips, or sep-
 aration or approximation  of  the jaws.   It  is then  easy
 to understand, how it  may  serve   for the prehension of
 aliments.  These organs act as pincers, and seize the
 bodies which are to be introduced into  the mouth.  In
 most animals, these  organs are  situated  anteriorly, to
 seize the aliments; but in man, and some other  animals,
 this function is discharged by other members.   The  hand
 places the aliments in the mouth,  and the jaws  approxi-
 mate only to retain them there.
   Liquids are taken in two ways; sometimes the liquid
 is turned into the  mouth, and  falls by its own weight;
 at other  times, it is sucked in, either by the dilatation of
 the thorax, which thus  determines  the entry of  air into
 the lungs,  or by the movements of the tongue, which by
 retreating  backwards, acts in the  manner  of a  piston;
 the latter constitutes the phenomenon of  sucking.
   Fluids do not ordinarily remain in the mouth,   stoppage of
                                             the aliments
 but descend at  once  into the stomach ;  while in the mouth-
 the solid aliments remain  in  it a certain  time,  and are
 submitted to mastication and  insalivation.
   Mastication, or the mechanical division  of the Mastication.
aliments is effected by the teeth.
   These organs are bodies of an extreme dura-  Teeth.
bility, implanted in the border of either jaw, so as to act
upon each  other.   They greatly resemble bone, but  dif-
                   15 
114           ANATOMY AND PHYSIOLOGY.

fer in one important respect;  for bones are living parts,
and constantly nourished, as shown  by the experiments
upon  their coloration, while the teeth do not  live ;  they
are not the seat of a nutritious movement, and the mate-
rials of which they are composed, are not renewed.   In
this they resemble the hair, nails, and all  the products se-
creted by the glands, such  as  the  saliva, bile, and urine.
Only in the place of being always liquid,  as  the latter,
they  soon become  solidified, and acquire an extreme
durability.
  Mode of forma-   Tne teetn are          Fig. 19.'
                                  a           c
formed by secretory  organs      <,
contained  in  the interior  of    ^J           jm
the jaws, (d,  fig. 19).  These d  ^^^^^sa^rnKm^i^ f
organs are small membranous    HggPp          'iW
sacs,  (capsules, or matrices of &--*''    ■^■38BHHHHP^x-_ c
the tooth,) at the bottom of which is a small  pulpy
nucleus, called the germ, and in which ramify many ner-
vous  filaments, and a great number of blood-vessels, (fig.
20).   The bulb, or germ, (b,) permits a gelatinous humor
to transude, which fills the capsule, (a,) and there is soon
deposited upon its superior surface some  grains of a stony
substance, (d, d,) which enlarge by the exudation of a
new  quantity of matter, and unite so  as to envelop the
pulpy nucleus, from which  they originate.   The  solid
envelope, resulting  from this  species of crystalization, is
moulded  exactly upon the germ, and as this is to con-

  1 This figure represents the lower jaw of a very young infant; the greater
part of the exterior surface of the bone has been removed to expose the cap-
sules of the teeth in its interior; a, gum;  b, inferior  border of the jaw; c,
angle of the jaw; d, capsules of the teeth; e, coronoid process; /, condyle
of the jaw. 
                       DIGESTION.                   U5

stitute the tooth, the  form of these bodies    Fi<
must depend upon that of the  germ itself.    \
In proportion as this  organ allows a new  «.....
quantity of  stony  material to exude, the
latter is gathered to that previously formed,
and  constitutes a new layer, situated upon
the preceding.  The  tooth thus enlarges by the addition
of successive and concentric  layers,  and  the  germ  is at
last  found contained in a canal, occupying the middle of
this  body, and which diminishes as  new  materials are
interposed between this organ and the substance of the
tooth.  When the  germ  adheres to the bottom of the
capsule only by a single  point, the tooth can terminate
only by one  prong, or root; but if this organ adhere  by
several points, the  stony  matter secreted by it, penetrates
between  the peduncles,   envelops the  part beneath the
germ, and by its prolongation forms  as  many prongs, or
roots, as there are  points of adherence.
   Thus is the body of the  tooth formed, and  s|™tt^„f
developed ;  but while the stony matter is thus being de-
posited by layers on its interior, the  surface becomes en-
crusted by a still harder  substance, which is formed  by
the capsule,  and is called the enamel, while  the  central
part secreted by the germ is called the ivory.   Upon the
superior part of the sac, enveloping the germ,  a multitude
of very minute vesicles may be observed, which  are ar-
ranged with  much  order, and which secrete  a  peculiar
liquor, which expands by  minute  drops upon the tooth,

  1 Section of the capsule of a tooth magnified to  show the disposition of
the germ, and the manner, in which the stony matter is deposited upon its
surface ; a, capsule; b, bulb or germ; c, blood-vessels and  nerves,  which
penetrate to the  bulb ; d, d, first rudiments of the tooth. 
116           ANATOMY AND PHYSIOLOGY.
thickens and  forms  the kind  of varnish  already  men-
tioned.
  In  man  and the  carnivorous  animals, the  teeth  are
formed solely of these two substances, the ivory and  the
enamel; but  in  the herbivorous mammiferae, some of
these  bodies present a third substance, which  covers  the
enamel, and is  therefore called the cortical;  it is secre-
ted by the capsule, and much resembles the ivory.
  chemical    The ivory of the teeth is composed of  gela-
composition of           J                    j.         o
the teeth.  tme^  mixe(j ^vith the phosphate of lime, (in the
proportion  of  about  sixty parts  to  the hundred in  the
adult  man,) and containing  also  a small quantity of the
carbonate of lime  (ten  to the  hundred  parts  of ivory).
The enamel contains only twenty to the hundred of ani-
mal matter, and eight of the carbonate of lime.  Accord-
ing to some chemists there is also a  florate of  lime ;  but
the existence of this material does not appear  to be con-
stant, and in any case it is only met with in small quan-
tities.   But the enamel is particularly distinguished from
the ivory, by its compact and fibrous tissue, its  color, and
its hardness, which is so great that sparks may be elicit-
ed by collision with  steel, like the flint.
  ?fthL°torth!   As  the  tooth increases by the addition of
new layers, either of ivory,  or enamel, it approaches  the
edge  of the jaw, then traverses it, issues from the  gum
with which this border  is  furnished, and appears exter-
nally  ; but the inferior part of the tooth which  is of later
formation, remains in the jaw and serves to fix it there.
The name of alveolce is given to the  bony cavities in
which the teeth are  implanted, and  that of  roots to  the
parts  enclosed :  that part which  appears above the  gum
is called the crown, and the neck is the connexion of the
crown and root. 
                     DIGESTION.                   H7

  The roots differ also from the crown of the  teeth by
the absence of enamel, with which the latter is,  on the
contrary, covered ;  and the cause of this  difference evi-
dently resides in the position of the part of the capsule,
which secretes the stony varnish :  it is in relation with
the superior part of the teeth, but does not descend to
the peduncle of the bulb, where the roots are formed.
  The teeth present  different  forms,  and their Fot™thfthe
uses vary with the nature of these differences ;  some ter-
minate by a thin sharp edge, serving to cut the substan-
ces introduced between the jaws,  and have received  the
name of incisors,  (fig.  21, a, b,).   Others are conical,
and in most  animals advanced beyond the neighboring
teeth ; they do not serve  to cut the aliments as the inci-
sors, but to lay hold and tear them ; they are  called  the
canine teeth,  (c,).   Lastly, others  terminate by a  broad,
unequal surface, and present the  most favorable  condi-
tions for crushing and grinding  the  aliments;  these  are
the molar teeth, or grinders, (d, e,f g, h,).
  In the study of animals, the disposition of the teeth is
found to vary, according as these beings are to be  nour-
ished upon animal or vegetable  substances, soft flesh, or
little animals hid under a  coriaceous or horny coating, as
insects, tender herbs,  or firm wood; and  to such a  de-
gree that by the mere inspection of these organs, one may
obtain with much certainty a knowledge of the regimen,
manners, and  even general structure,   of most  mammi-
ferae.
  The mouth of  man is  furnished with the three  kinds
of teeth already mentioned,  and  the  manner  in  which
they are planted in the jaw varies as much as  the form
of their crown.  The incisors,  (a, b,) whose action tends 
118
ANATOMY AND PHYSIOLOGY.
to bury them in their alveolae, rather than tear them out,
have  but a single root quite short.  The  canine teeth,
(c,) extend into the jaws more deeply than the  incisors,
and the molars, (d, e, f g, h,)  which  must support  the
greatest efforts,  present two or three diverging roots,  to
augment the solidity of their insertion.
                       Fig. 21.J
         h     g     f    e     d   c   b   a
 First^denti-   ^t tne periocj 0f birth, the development of the
teeth is but little advanced; it is very seldom, that any
of these bodies have yet pierced the gum, and their evo-
lution does not commence till the age of six months, or a
year.   The teeth, which then form, are destined to fall
out at the end of a few years, and to give place to others.
They are called milk-teeth, or of the first dentition, and
are twenty in number, viz.: in  each jaw,  four  incisors,
which occupy the  front of the mouth, two canines, situa-
ted one on each side next the incisors, and  four  molars,
placed at the bottom of the mouth, two on each side.
 SetCit"on.den"   The teeth of the  second dentition are more
numerous than those  of the first; the complete  number
of these bodies is  thirty-two, viz.: to each jaw,  four in-
cisors, two canine, and ten molars, the two first of which
on each side  have but two  roots, and are  called small

 1 Teeth of an adult: a, first incisor ; b, second incisor ;  c, canine; d and
e, small molars ; /, g, h, large molars. 
DIGESTION.
119
molars, (fig. 21, d, e,) while the  three next,  situated at
the bottom of the mouth, are  provided with three roots,
and called large molars,  (f g, h,).
   In extreme old  age, these teeth fall out  as the milk-
teeth  of infancy,  but are not replaced, and their alveolae
are obliterated.
   The teeth, the development and structure of  Scation*
which  we  have  been studying,  are  the passive instru-
ments of mastication : they are  moved with the jaws in
which they are planted.   The upper  jaw does not move
upon the  rest  of  the head, but  the  lower, whose form
resembles a horse shoe, articulates with the cranium only
by the extremity of its two branches, and  may be sepa-
rated from, or approximated  to the upper jaw.  A great
many muscles are  fixed  to this bone, and impress upon
it their motions.   Its depression  is determined  by  the
contraction of those which extend from its inferior border
to the os  hyoides.   The contrary effect
is produced by the action of the mus-
cles, extending  from the  different points
of  its surface  to  the temples, and the
neighboring parts  of  the head.2   The
power of the levator muscles of the jaw

  1 a, Inferior jaw, — b, articulation of the lower jaw with the cranium,
— c, masseter muscle, — d,  zygomatic arch, — e, temporal muscle,— /,/,
orbicular muscle of the lips, — g, orbicular muscle of the orbits, — h, occi-
put, or posterior part of the cranium.
  2 The principal levator muscles of the lower jaw,  are, 1st, the temporal
muscle (e, fig. 22), which springs from the  coronoid  process of this bone
(see fig. 19, e), passes under the zygomatic arch  (d),  and extends upon the
sides of the head to which it is fixed;  2nd, the masseter muscle  (c), which
extends from the external face of the angle of the jaw to the  zygomatic
arch (d); 3d, the two pterygoid muscles, which occupy on the internal face
of the jaw the place corresponding to that of the  masseter, and are fixed to
 
120
ANATOMY AND PHYSIOLOGY.
 is very great, and by their contraction, the substances in-
 troduced between the teeth are  compressed  the more
 forcibly, when placed near the bottom of the mouth, and
 consequently near the fixed points of these muscles.
   The  aliments  are continually  thrown  between the
 teeth by the contractions  of the cheeks, or by the mo-
 tions of the tongue ; and  thus pressed between two sur-
 faces, hard,  very unequal,  and  whose  asperities are
 adapted to each other, these substances are soon divided
 into small portions, and crushed.
  influence of   The importance of this operation is very great,
 mastication up-         *■               *■             J °    '
 on digestion. for tne more complete the mastication the more
 easy is the digestion : which  is as  easily proved as un-
 derstood.  If an  animal  be made to swallow  pieces  of
 meat of various sizes, and after a certain time it is killed
 and the  stomach opened,  the  smallest fragments will be
 the most advanced in digestion, and the superficies of the
 greater will hardly have  been touched, while the smaller
 portions will be completely softened.   Now this happens
 when fragments unequal in size, of any body susceptible
 of being dissolved in this liquid, are plunged  into water,
 sugar, for example.
 of ShnenS!  While the aliments are submitted to the me-
 chanical division, they imbibe saliva,  and are sometimes
 even dissolved in it.
  saliva.    The  saliva is  a colorless liquid,  transparent,
 slightly viscous, which continually flows into the mouth,
 the lower parts of which it occupies.   Chemical analysis
 has demonstrated, that it is composed  of about 993 parts
of water to  the  1000 ; the other seven thousandths are

the base of the cranium on each side of the posterior opening of the nasal
fossae. 
                      DIGESTION.                  121

formed as follows ; of a peculiar animal matter about three
thousandths, of mucus 1.4; chloride  of sodium (or ma-
rine  salt), chloride of  potassium, tartrate of soda, and a
small quantity of free soda, which gives to this liquid its
alkaline properties, make up the remainder.
  The mixture of the  saliva with the  aliments is a cir-
cumstance  of  more importance,  than would  at first be
supposed.  It facilitates mastication,  aids powerfully de-
glutition, and, as we shall  hereafter see, appears to per-
form an important  office, in the  digestion of these sub-
stances.
  The glands, which form the saliva, are situated   S$IH7.
around the mouth,  and are composed  of small agglomer-
ated granulations.  In man, there are three pairs,  placed
symmetrically upon each side of the  head :  the parotid
glands situated in front of  the ear, and behind the lower
jaw; the submaxillary glands, lodged under the angle of
the jaw (m, fig. 23), and the sublingual glands (I) placed
beneath the tongue, in the space between the two sides
of the jaw.
  Each of these glands communicates  with  the  mouth
by a peculiar excretory duct, and pours into it the saliva
in variable quantities.  With  a tolerable appetite, the
sight of aliments is sufficient to determine a more con-
siderable afflux, and the presence  of a foreign body in
the mouth, even  if it be completely insipid,  always ex-
cites the secretion of  this  liquid : it would appear, that
upon mastication it becomes more alkaline than usual.
  So long as mastication is unfinished, the pos- l&aiVmenti"'
terior opening of the mouth is closed by the velum palati,
which descends and rests  upon the base of the tongue.
The aliments  cannot then  penetrate  farther into  the di-
                   16 
122
ANATOMY AND PHYSIOLOGY.
gestive  canal:  but  when this  operation  is  terminated,
this movable  separation  of the  mouth  from the pharynx
is raised, and deglutition goes on.
                                 This name is  given  to the
                              passage of the aliments from
                              the  mouth  to  the  stomach,
                              through  the   pharynx  and
                              aesophagus.
                                 The pharynx,  or posterior
                             fauces, is a cavity continuous
                              with the mouth, and which is
                           m placed at the superior part of
                           d  the  neck  (fig. 23  and  24.)
                              By its summit it  communi-
                              cates  with  the nasal fossae ;
                              and  above and in  front,  it is
                              separated   from   the  mouth
                              only  by  the  velum  palati.
Below and in front,  the larynx (e), opens into it; lastly,
  1 This figure represents a side view of a vertical section of the mouth
and pharynx; — a, the nose, — b, the upper lip, placed in front of the arch
of the palate, which extends horizontally backwards, and separates the
cavity of the mouth from  the nasal fossae, — c, the tongue,  the base of
which is fixed to the os hyoides (d), — e,  the larynx suspended to the  os
hyoides, and opening into the pharynx, —/, portion of the trachea, a tube,
which continues with the larynx at one end and at the other communicates
with the lungs, — g, portion of the base of the cranium, to which is sus-
pended the pharynx (h), — i, commencement of the aesophagus, — k, section
of the velum palati; above  this partition is the posterior opening of the
nasal fossae, and below are two kinds of pillars, between which are situated
the tonsils, — I, sublingual gland placed beneath the tongue, and com-
municating with the mouth by a small excretory duct, directed forward, ~
m, submaxillary gland, placed behind and below the preceding, — n, thyroid
body, a kind of imperfect gland, placed in front of the inferior part of the
larynx. 
                          DIGESTION.                     123

 below and behind, it  continues into  the  aesophagus (i) ;
 a long and narrow tube, which descends the whole length
 of the neck, traverses the  thorax, passing between the
 lungs, behind  the  heart, and  in  front of the vertebral
 column, perforates the diaphragm, and at last terminates
 at the stomach.
    The velum  palati,  which           /^v  24.'
 separates  the   mouth from
 the  pharynx,  is  a  movable
 partition,  suspended  trans-
 versely  from  the  posterior
 border of the palate, and free
 at its inferior  border,  which
 is  prolonged  in  the middle  /.
 to a point, called the  uvula
 (fig. 23, k, and 24, d).  It is
 formed by a  fold  of the mu-
 cous membrane, which lines
 the whole digestive  canal,
 and contains  in its interior a                h


  1 The pharynx seen from behind,  and opened  to display the relative po-
 sition of the posterior  openings  of the nasal fossae, of the  velum  palati,
 base of the mouth and  opening of the larynx ; — a, base of the cranium, —
 b,  mastoid process  of the temporal  bone, situated at the side of the
 base of  the cranium behind the ear, — c, vertical partition of the two
 nasal fossae, the termination of which may be seen at the superior part of
 the posterior fauces, — d,  velum palati,  making part of the arch  of the
 palate; in the middle of its inferior  border is found a prolongation, called
 the uvula, and on each side of this appendix is seen the buccal cavity, — e,
 base of the tongue,—/, extremity of the  os  hyoides; on the opposite side
 this bone is entirely concealed by the portion of the posterior wall  of the
pharynx, which is turned outwards, — g, opening of the larynx or glottis;
conducting to the lungs by the trachea, a  kind of valve, called  epiglottis,
opens upwards and in front of this opening;  it is here applied against the
base of the tongue, —A, portion of the trachea, —i, commencement of the
aesophagus, — £, one of  the levator muscles of the pharynx.
 
124
ANATOMY AND PHYSIOLOGY.
great number of  muscles,  which  allow it  to  execute
many motions ; to descend and rest upon the base of the
tongue, to be raised and carried  obliquely backwards
toward the posterior wall  of the pharynx, so as to inter-
cept more or  less completely the  passage  between  this
cavity and the nasal fossae.
of degSo™   Deglutition appears to  be  very simple,  and
yet it is really the  most complicated of all the operations
of digestion.   It is produced by the contraction of a great
number of muscles,  and requires the  concurrence of
several important organs.   All the muscles of the tongue,
velum palati,  pharynx, larynx, and  aesophagus take  part
in it.
   When it is to  commence, the  aliments are  collected
upon the back of  the tongue, which is raised, and presses
them  from before backwards  against  the velum palati;
this partition  then rises to a horizontal  line, and thus  per-
mits the aliments  to issue from the mouth; if it did not
oppose the motion impressed upon these substances by
the movements of the tongue, the aliments would pene-
trate  the  nasal  fossae;  but the  direction it occupies,
obliges them  to descend  into the  pharynx.   This  first
period  of  deglutition  is under the  direction of the will;
but not so with the remainder of this operation, and  the
motions, by means of which the  aliments arrive at  the
inferior part of the pharynx, are involuntary and in some
sort  convulsive.   The alimentary bolus (for thus each
mass of the  aliment  swallowed is called), then passes
over but a very small space ;  but it must avoid the open-
ing of the larynx,  and that of the nasal fossae, where its
presence would be injurious, while  its passage must be
so prompt as  to offer but a momentary interruption  to the
free communication of the larynx with the external air. 
DIGESTION.                    125
 ,  Let us see how nature accomplishes this important result.
   The alimentary bolus no sooner touches the pharynx,
than every thing is called  into action.  This cavity con-
tracts and embraces the alimentary bolus, while on the
other hand the larynx ascends and passes in front of this
body, to render more rapid its passage over the opening
of the glottis.   Finally, during this movement, the edges
of the opening  close  exactly, and the epiglottis, pressed
against the base of the tongue, descends so as to cover
the entrance of the  larynx.   Thus the alimentary bolus,
continually  pressed  by the contraction of  the pharynx,
slides  upon  the surface  of  the  epiglottis, and  arrives
at the aesophagus, the cir-
cular fibres of which, by
successive   contractions,
drive it into the stomach.
   The  stomach (fig.  18,
b), is an enlarged portion
of the  alimentary  canal,
which is continuous with  m'"
the aesophagus, and which
is  the seat of  the  most
remarkable phenomena of
digestion, the transforma-
tion of the  aliments into
chyme.   It is a membra-  e'
nous sac placed across the
superior part of  the abdo-
men, and in form resem-
bling  a  bag-pipe.1    It
  1 In fact, the bag-pipe is constructed from the stomach of those animals,
in whom this organ most resembles man. 
 126           ANATOMY AND PHYSIOLOGY.

 gradually diminishes from left to right, and curves upon
 itself, so that its superior  border is concave and  very
 short while its inferior border (called the great curvature
 of the stomach) is convex and very long.   Toward either
 third of the stomach  there  exists, especially  during di-
 gestion, a contraction which  divides  the organ into two
 parts ;  that situated to the right called the  cardiac por-
 tion of the stomach,  that to the left called the pyloric
portion.  The opening, by  which this viscus communi-
 cates with  the aesophagus, is also called the cardiac ori-
fice, because it is situated on the side of the heart.   That
 which  conducts  from  the stomach  to the  intestines  is
 called  the  pylorus,1  and  is  situated  at the extremity  of
 the  pyloric part.
   The walls  of  the stomach are  very extensible :  when
 its cavity is not  filled with  aliments  they contract, and
 there are upon its internal  face a multitude of folds, the
 number of which diminishes  in proportion  to the disten-
 tion of the organ.   We  also  remark upon  the surface  of
 the mucous membrane  which  lines  the stomach, a very
 considerable   number of  small  secretory  cavities,  called
 gastric follicles,  which  pour out upon the  aliments the
 liquid they secrete.
  Gastric juice.  This  liquid,  which is called the gastric  juice,

   1 The word pylorus is derived from  the greek nvlovqbg, gate keeper,
 {nvlrj a gate and ovgog a keeper), and has been  given to the intestinal  ori-
 fice of the stomach, to signify the functions it fulfils;  while the aliments
 are as yet not sufficiently digested to allow of their passage into the intes-
 tine, the pylorus remains contracted and does not open to them a passage;
 but when the  aliments are converted into chyme, this opening relapses and
 allows them to pass.  The name of valve of the pylorus is given to a circu-
 lar fold, which surrounds this opening, and which is formed by a fold of the
 mucous and muscular tunics of the stomach. 
DIGESTION.
127
is, as we shall hereafter see, one  of the most important
agents of digestion, as by its action the aliments are con-
verted into chyme.  When the stomach is empty,  it is
formed in very small  quantities ;  but when the  walls of
this cavity are excited by the contact of food, and  espe-
cially of solid food, the gastric juice flows  in abundance,
and has always very marked  acid properties.   This acid-
ity appears to be  due in part  to the  free hydrochloric
acid, and partly to the presence of  a peculiar substance,
which  is  also met  with in the milk, and is  called the lac-
tic acid.   Some salts may also be detected in it, such as
marine salt, phosphate of lime, etc., and  about ninety-
eight hundredths of water.
   The alimentary substances, which accumulate Delay of the
                ■'                              food in the
in the stomach,  are  strongly pressed  upon  by stomach-
the action  of the  muscular walls of the  abdomen, and
would remount into the aesophagus, if the  portion of this
duct near the cardia were not closed  by the contraction
of its muscular fibres.   Sometimes this resistance is over-
come,  and the food  reascends to the mouth, or is even
thrown out, which bears the name of regurgitation, or
vomiting.
   On  the other hand,  the food  cannot simply traverse
the stomach, and then at once  enter  the  intestines, for
the opening of the pylorus is completely closed by the en-
ergetic contraction of the muscular fibres,  by which it is
surrounded.  The food  must  therefore  remain in  the
stomach, where it accumulates  principally  in the cardiac
part, or  great cul-de-sac of this organ.   Some of the in-
gesta are there simply absorbed by the walls of  the sto-
mach, and penetrate into the blood without any previous
alteration ;  this is the case with water, diluted alcohol, 
128           ANATOMY AND PHYSIOLOGY.
and some other liquids.  Other substances pass into the
intestine, and are even expelled  as excrements without
any alteration ; but the aliments are here  digested, and
thus transformed into a pulpy and semi-liquid mass, called
chyme.
 fhe™hymne.of  The fragments, placed towards the surface of
the alimentary mass, and near the walls of the  stomach,
early  imbibe the  gastric juice,  become acid  as  is this
liquid, and gradually soften  from the superficies towards
the centre.   The whole mass of  the  food finally  under-
goes the same alteration, and in consequence of this soft-
ening, these substances are  transformed into a  soft, pul-
taceous, grayish  matter, of a faint and peculiar odor,
which is chyme mixed with the remains of the food.  A
white substance is formed upon the walls of the stomach,
resembling  the  white of an egg  partially cooked, and
which mingles with the other products  of the  stomachic
digestion.
   These alterations take place with more rapidity in the
portions of the stomach  near the  pylorus  than  in the
great cul-de-sac, and are propagated from the superficies
of the alimentary mass to its centre.
  peristaltic   While chymification is going on,  the walls of
movements of           J             °   °
the stomach, tne stomach become the seat of circular contrac-
tions, which at first proceed from right  to  left,  so as to
propel the chyme by which the  alimentary mass is cov-
ered  towards the great cul-de-sac  of  the  stomach; but
after a certain time, all these vermicular motions,  which
are called peristaltic, take place in an  opposite direction,
and  convey the chyme to the pylorus, and then into the
small intestine. 
                       DIGESTION.                   129

   All alimentary substances are not transformed Duration of
                                              the digestive
 into chyme with equal rapidity.. The observa- process-
 tions and experiments, which have  been made upon this
 subject, demonstrate that muscular  flesh is much easier
 of digestion than most herbaceous substances ; that cook-
 ing exerts a great influence upon it, and that boiled veal,
 for instance,  is two thirds more digestible than  roast;
 that the skin and tendons resist a long time the action of
 the  stomach, etc.   Great differences  however  exist in
 different individuals : the size of the  pieces  swallowed
 also influences their transformation into chyme, as might
 easily be inferred from the  nature of the  digestive pro-
 cess.
   In general, the aliments  remain  several hours in the
 stomach  before  they  are  completely  transformed into
 chyme.
   A  great number of experiments have been ■ cause of the
                         x                    transformation
 made with the view of ascertaining  what passes fnlothym!ma
 in the stomach during digestion.   The most remarkable
 are  those  of Spallanzani, a celebrated physiologist of
 Modena.   At the  time when  he entered  upon his re-
 searches, it was thought that this phenomenon was onlv
 a species of  trituration, and that the chyme was merely
 the food bruised  till  reduced to pulp : but Spallanzani
 showed this  not  to be the  case.   He caused birds  to
 swallow articles  of food  contained in tubes,  and little
 metallic  boxes,  the walls of which were  pierced with
 holes, so as to preserve these substances from all friction,
 but not to withdraw them from the action of the liquids
contained in the stomach, and he  found that digestion
took place  as under  ordinary circumstances.  He there-
fore justly  concluded, that the gastric juice must be the
                  17 
130
ANATOMY AND PHYSIOLOGY.
principal cause of  the  chymification of food,  and to be
more completely assured, he  had recourse to very inge-
nious experiments.  He  made crows and  other  birds
swallow little  sponges attached to a thread, by means of
which he withdrew these  bodies  from the stomach  after
they had remained there for some minutes, and  had im-
bibed the liquids contained in this cavity.   Thus he pro-
cured a considerable quantity of the gastric juice, which
he placed in small vessels with the food suitably divided ;
he took care at the same time to  raise the temperature,
so as to imitate as nearly as possible the circumstances
under which chymification  takes place ; and  at  the  end
of some hours he found  the alimentary mass, submitted
to this artificial digestion, transformed  into a pulpy mat-
ter, similar in  all respects to that which would have  been
formed in the  stomach  by a natural digestion.  Thereby
proving  that the action of the gastric juice upon the food
is the principal cause of its transformation into chyme.
  intestines.   That portion of  the  alimentary  canal, into
which the food penetrates after its digestion  in  the sto-
mach, bears the name of intestine (fig.  18, c,  d).  It is a
membranous and convoluted tube, small in diameter, but
very long, in man  being about seven times the length of
the body.
  In animals nourished  exclusively upon flesh, the intes-
tines are, in general, shorter than in  man,  and other om-
niverous animals;  while in the herbivorous, their length
is much more  considerable.   Thus in the  lion it is only
about three times  that  of  the  body, and  in  the ram it
often equals twenty-eight times this length.   The reason
of this difference is obvious, for it is evident that herba-
ceous substances,  which are very slow of  digestion, and 
DIGESTION.
131
which contain but a really small portion of nutritive ma-
terials, must be taken  in  greater  quantities, and  must
remain a longer time in the alimentary canal than mus-
cular flesh, the digestion of which is very prompt, and of
which nearly the whole mass  is composed  of nutritive
materials.
   The intestines, as we have already said, are lodged in
the abdomen, and  enclosed by the folds of the perito-
neum, which fix  them  to the  vertebral column.   They
are divided  into two distinct parts, the  small  and the
large intestine.    The small intestine makes the  Smtaine!ntes"
continuation of the stomach, and in its  interior digestion
is finished.   It is  very narrow,  and  constitutes  about
three fourths of the whole length of the intestines.  Its
exterior surface  is  smooth ; the muscular fibres which
surround  it,  are  placed side  by side;  and  the  mucous
membrane, lining the interior,  presents upon its surface
many small follicles, and a great number of prominent
appendages,  called  villosities,  also a  great  number  of
transverse folds called valvulce conniventes.   The follicles
secrete a viscous humor very considerable in  quantity;
the villosities, as we shall afterwards see, appear to serve
especially for the absorption of the  products of digestion ;
and the valvulae conniventes to retard the  course of the
chyme.
   Anatomists  distinguish  in  the  small intestine  three
parts, the duodenum, so called  because its length  is about
equal to twelve fingers, the jejunum, because in the dead
body usually found empty, and the ileum,  (from edeip  to
turn, to twist), but this distinction  is of little importance
in physiology.
   The alimentary matters which enter  this in-  Fluids con-
                                             tained in  the
testine, are mixed with the  humors secreted  bv tine!1 intes' 
132
ANATOMY AND PHYSIOLOGY.
its  walls,  and  with two peculiar  fluids,  the  bile  and
pancreatic juice, each formed in distinct glandular organs
situated in the neighborhood of the stomach.
 The Hver.   The liver (fig. 18, /,)  which is the productive
organ of the bile, is the largest viscus of the  body.  It
is situated at the  superior part of the  abdomen, princi-
pally upon the right side, and descends to the lower bor-
der of the false ribs.   Its superior face is convex, and its
inferior  irregularly  concave.   It  is  divided  into three
lobes,  the largest of which is situated to the  left,  and
separated from the right by a fissure, and  the smallest
(called  the lobule)  is  placed under the others.   The
color of this organ is  reddish brown upon the  surface,
and yellowish in the interior.   Its substance is soft  and
compact, but  traversed  by  a multitude of canals,  and
when torn it appears to be formed by the agglomeration
of small solid granulations, into which the blood  vessels
empty,  and from which  originate the  excretory ducts
carrying off the bile.
  These excretory ducts successively unite to form twigs,
branches, and lastly a trunk, which issues from the infe-
rior face of the liver in  the direction  of the  duodenum;
and which, in its  course communicates with a  membra-
nous sac adherent to the liver, habitually distended with
bile, and called  the gall-bladder.   The  termination of
this canal may be seen in the duodenum, at a  short  dis-
tance from the stomach.1
  The liver presents a very remarkable peculiarity.  The

  1 The excretory duct immediately from the liver is called the hepatic duct,
and  that from the bladder the cystic duct.  Finally the common trunk,
formed by the union of these two vessels, is called the ductus choledochus
(from /oXt], bile and So^dc, the  container. 
DIGESTION.
133
greater part of the blood, which circulates in this organ,
is not arterial, as in the other  parts of  the  body.  The
venous blood  coming from the intestines enters it by the
vena porta, which ramifies like an artery, and  it would
even appear, that  the formation of the bile depends  prin-
cipally upon this liquid.
   The bile is  a viscous, ropy liquid, greenish, and  Biie.
of a very bitter taste.   Its chemical composition is very
complicated, for we find in it water, albumen,  resinous
matter, a yellow coloring principle, various fatty matters,
several salts, and free soda.   It is always  alkaline, and
has some analogy to soap.
   The bile is constantly flowing  into the intestine, but
the flow appears to be increased in quantity during diges-
tion ;  for when the stomach is empty the gall-bladder  is
full, and when digestion is  terminated, this reservoir  is
nearly empty.
   The pancreatic juice is very analogous to  the   Fanu%ftic
saliva, both in  physical  properties and chemical  com-
position ;  the  pancreas,1 which forms it, resembles the
salivary glands.   It is a granular  mass,  divided  Pancreas.
into a great number of lobes and lobules, of  firm consist-
ence,  whitish gray color bordering  upon  red, placed
crosswise between  the  stomach  and  the vertebral  col-
umn (fig. 18,  n).   From each of its  granulations there
originates an excretory duct, all of which unite together
as the veins, and  thus form  a canal  opening  into the
duodenum near the mouth of the ductus choledochus.
  We have already seen how the peristaltic move-  Delay of the
        c  ,                                   chyme in the
ments of  the stomach propel the chyme into the intestine

  1 The word pancreas signifies all of flesh (from nav, all, and x^a?, flesh),
and was given to this gland by the ancients. 
134
ANATOMY AND PHYSIOLOGY.
 duodenum through the pylorus.  This opening is supplied
 with a valve, which opposes the return  of this material
 to the stomach,  and the presence of the chyme in this
 intestine causes in it contractions analogous to those of
 the stomach, and which exactly resemble the movements
 of a crawling worm.  By  the  aid of these movements
 the chyme  accumulates  in  the intestine, and  gradually
 advances  farther in the tube.  During this passage  it
 mixes with the bile, and the other humors in its course,
 and gradually changes its properties ;  it becomes yellow-
 ish, bitter, loses its  acidity, then becomes  alkaline, and
 at the same time there is separated from it a matter more
 or less thick, sometimes white, sometimes gray, according
 to the nature of the aliments, from which it arises, which
  chyie.   is attached to the surface of the intestinal mucous
 membrane,  and which bears  the name  of chyle.   This
 matter, as we shall afterward see, is absorbed, and toward
 the inferior  third of the small  intestine  is no longer met
 with; the paste formed by the residue of the chyme, by
 the bile,  and the  other  humors already mentioned, ac-
 quires in this portion of  the alimentary  tube more con-
 sistence, takes a deeper color, and passes into  the intes-
 tine to be rejected as excrement.
  Ingassesal    Digestion then is finished in the small intestine,
 and during its performance various gasses are disengaged
 from the alimentary mass, which more or less  dilate the
 intestine.   These  gasses  are  principally carbonic acid
 and  pure  hydrogen; sometimes too azote is found with
 them.
  Lartfneintes"  The large intestine, (fig. 18, e, g, h, i,) which
is the continuation of the small, and which receives the
residue left  by digestion,  may be easily distinguished  by 
                       DIGESTION.                    135

the  numerous dilatations  of its walls between the  col-
lections of its muscular fibres.  It is  divided into the
caecum, colon and rectum.   The ccecum,1 which is  ccecum.
situated near the haunch  bone of the right side, is  pro-
longed into a cul-de-sac beyond the point of insertion  of
the small intestine, and presents at this extremity a  ver-
miform appendix.   Folds arranged  as valves supply the
opening from the small intestine, and prevent the matters
driven into the ccecum from reentering  the ileon, and re-
turning to the stomach.
   The colon, (derived from xutio, I stop, because  colon.
this intestine retains for a long time the  excrementitial
matters in its folds), is continuous with the ccecum, re-
mounts towards  the liver,  traverses the  abdomen directly
beneath the stomach, and redescends on the left  side  to
gain the pelvis, where it continues into the rectum, which
terminates at the anus.
   The residue, arising from the digestion of the  Pr0gresS  of
food, is  driven by degrees from the  ccecum to tfedi1Sid?n
 1                n  i i           .  ,            the lar6e  in_
the rectum, so called because straight, where ittestine-
accumulates, and remains  for a longer or shorter  period.
By thus traversing the large intestine these matters ac-
quire greater consistence,  and a peculiar odor.   There  is
developed at  the same time in this intestine a considera-
ble quantity of gas, differing  essentially from  the gases
of the small intestines  by the almost constant  presence
of carbonated hydrogen, and sometimes also by the pre-
sence of a little  sulphureted hydrogen.
   The fleshy fibres around the anus, and which form the

  1 Anatomists have  named the first portion of the large intestine the cce-
cum, because it is prolonged inferiorly in the form of a cul-de-sac (from cau-
cus, blind). 
136
ANATOMY AND PHYSIOLOGY.
sphincter  muscle of this  opening,  are continually  con-
tracted, and consequently oppose the exit of matters ac-
cumulated in the large intestine.  In general, the  con-
traction of the  muscular fibres  around the intestine does
not suffice for  the expulsion of their  contents, the dia-
phragm and the other muscles of the abdomen concur to
the same  end,  by compressing  the mass of the viscera
contained in this cavity.
  "dftwn0/   Such are the principal phenomena of digestion.
Let us now inquire, if,  in the present state of science, it
is possible to explain in a satisfactory manner  the differ-
ent changes experienced by the food during the perform-
ance of this function.
  The  experiments of Spallanzani and of some other
physiologists show, that the principal agents of digestion
are the various liquids, which  moisten  the food in the
different parts of the digestive canal.   These  juices are
of  three  kinds: 1st, the saliva, always alkaline:  2nd,
the gastric juice, which is acid: 3d, the bile  and  pan-
creatic juice, which are alkaline as the saliva.
  By the action of the saliva the food is sometimes dis-
solved, in most cases, however simply softened, and often
without  much   change  in  its  physical  properties.   It
would appear that this  liquid plays an important part in
digestion, as may be seen from what takes place in ru-
minating  animals.
  In  these animals there are  four distinct cavities, to
discharge  the  functions of the single stomach of man.
The food is at first introduced into a large sac called the
paunch, when it remains a certain  time, and then passes
into the second  stomach (the reticule), and is thrown up
from the latter  into the mouth, to be bruised by the teeth 
DIGESTION.
137
and moistened  with saliva ; it next descends  into  the
many-plies or third  stomach, and thence into the reed.
The  experiments of  Prevost  and  Leroyer of  Geneva
show, that the aliments contained in the paunch and the
reticule are moistened with an alkaline juice, and  that
by its action the albumen and  some other substances,
of which they are in  part  composed, are  dissolved.   If
by pressure this liquid is forced out, and  acid thrown
upon it,  there is  immediately formed a flaky precipitate,
similar to the white  of an egg half cooked.  Now  pre-
cisely the same takes place, when  the alimentary mass
passes into the many-plies : it meets there an acid juice,
and deposits upon its walls a whitish layer, which is no-
thing but chyme.
   On the  other hand the  experiments  of Spallanzani,
which we  liave already had occasion  to mention, show
that the  food may also be directly attacked by the gastric
juice.  This liquid  may  dissolve substances, on which
the saliva is inert, and the principles thus dissolved must
in their turn  be  precipitated as solid globules, when  the
alkaline  juices  contained  in  the  small  intestine  are
mingled  with the acid products of  the stomachic diges-
tion.
   Digestion seems then  to  be the result of  the chemical
action of the saliva, gastric juice, and  bile, upon the ali-
ments, and upon the materials extracted from these sub-
stances by the action  of the digestive liquid, to which
they have been submitted before meeting either of these
two latter agents.  This phenomenon would then essen-
tially consist in the  solution of the alimentary  matters,
and their subsequent precipitation in the globular state ;
but it must be confessed, there  are very many points yet
                   IS 
138
ANATOMY AND PHYSIOLOGY.
to be elucidated relative to the theory of digestion, and
this question, the interest and importance of which every
one can appreciate, demands a new investigation.
 onhTchyie"   To terminate the study of this function, it re-
mains for  us to examine how the nutritious matter, ex-
tracted from the food by the digestive function, can pass
from the  intestinal  canal into the mass of  the blood,
which it is destined to renew.
  CvessfeiT.us   Some of the liquids introduced into the  sto-
mach are directly absorbed by  the veins  in  the walls of
this cavity, and in those of the small intestine;  but the
chyle follows another route, and penetrates into a partic-
ular set of canals, destined  to effect its transport.  These
                                    vessels called chylif-
                                    erous   (or   lacteals,
                                    from the appearance
                                    they take when fill-
                                    ed  with  chyle) be-
                                    long,  as  we  have
                                    already said, to the
                                    lymphatic   system.
                                    They arise from im-
                                    perceptible  orifices
                                    on   the  surface  of
                                    the villosities of the
                                    intestinal    mucous
                                    membrane, and unite
        *  h    b                     like veins into larger

  1 A portion of the small intestine with the chyliferous vessels originating
in it and the commencement of the thoracic  canal.
  a, portion of the intestine, — b, mysentery which fixes the intestine to the
posterior  wall of the abdomen,—c, radicles of the chyliferous vessels
 
DIGESTION.
139
or  smaller  branches, which  proceed  between the  two
folds of the mysentery to the vertebral column.  During
this course the lymphatic vessels traverse  a number  of
small bodies, irregular in form, and of a  pale rose color,
which  are called the  mesenteric glands (d), and  after
issuing  from  these  glands  they unite  into a common
trunk, called the thoracic duct (f).   This canal also re-
ceives the lymphatic vessels from almost all other  parts
of the body.   It traverses the diaphragm, and mounts in
front of the vertebral column  to the  base  of  the  neck,
where it finally terminates in  the  left subclavian  vein.
There are  in its interior, folds similar to the valves  of the
veins, so arranged, as to permit the passage of the liquids
towards the subclavian vein, but to prevent their return
to the intestine.
   If an  animal is fasting, these vessels are nearly empty,
but when the intestinal digestion is in full  activity, they
are soon gorged with chyle.
   The physical properties of this liquid vary with  chyie.
the nature  of the food, from which it arises, and the ani-
mals in which it is observed.   In man and most mammi-
ferae, the chyle is usually a white liquid, opaque, having
nearly the aspect of milk, of a salt alkaline taste, and  of
a peculiar odor.   Examined  by the microscope, it pre-
sents a  multitude of globules, analogous to those forming
the central nucleus of the globules of the blood.  When
at rest, it soon forms a mass, like the blood, and after the

creeping upon  the intestine, — d, mesenteric glands, —e, chyliferous vessels
after their passage across the mesenteric glands, —/, thoracic duct, — g,
enlarged portion of the thoracie duct called the reservoir of Pecquet (better
known as the receptaculnm chyli), — h, h, lymphatic vessels of the inferior
limbs going to the thoracic duct, — i, i, portion of  the aorta, by the side of
which the thoracic duct ascends to gain the subclavian vein. 
140           ANATOMY AND PHYSIOLOGY.
expiration of some time it separates into three parts; a
solid clot, which occupies  the bottom of the vessel, a
liquid analogous  to  the  serum, and a very thin layer,
which swims upon it, and which appears to be of a fatty
nature.   The chyle also takes during coagulation,  a lively
rosaceous tint, and if agitated with oxygen the phenom-
enon is yet more marked.
  Chyle, arising from articles of diet, which do not con-
tain fatty substances, is much less opaque than that  fur-
nished by matters containing fat or oil, and the layer
which forms upon the surface after coagulation is much
less thick.  The solid clot, which is principally  com-
posed of fibrine  and coloring matter,  is very small in
quantity in the chyle arising from  the digestion of sugar,
gum, etc., while from the  chyle furnished by muscular
flesh is formed a considerably large one.
  Mechanism   The villosities, with which the surface of the
of the chylous                '
absorption.   mucous membrane of the intestines is supplied,
appear to be  the special agents of the absorption of the
chyle.   As soon as it commences, we  find them  swollen
and saturated with  this liquid, as sponges which have
imbibed  milk;  some anatomists  have imagined they
could distinguish in  this species of fringe, very small
openings communicating with the radicles of the lym-
phatic vessels; and  if this  be the case, we  can easily
comprehend, how the chyle  may  penetrate into these
vessels without being absorbed by the veins.  This liquid
contains, as we have already said, globules  too large to
pass through the simple  porosities of  the  venous walls,
while they would find an easy access into the chyliferous
vessels through the holes, with which  the  villosities ap-
pear to be pierced. 
DIGESTION.
141
  However, the chyle penetrates into these latter ves-
sels, and flows with  considerable rapidity the length of
the thoracic duct to the left subclavian vein ; if this canal
be tied in the living animal, the passage of the chyle into
the circulatory system is  completely cut off, and  this
liquid accumulates in the thoracic duct.   The cause of
its movement of  ascension in this canal, and in the nu-
merous chyliferous vessels, which represent the roots of
this trunk, is not known.  It is found to  continue some
time after death, and it  has  also been  ascertained,  that
the course of the chyle is  favored  by the  respiratory
movements, the beating of the arteries, and all the move-
ments, which compress in an intermitting manner the
thoracic  duct, and which can be  readily comprehended,
by reason of the valves already mentioned, and the action
of which has been explained when treating of the venous
circulation.
   The chyle thus mingling with the blood serves  Uscny0ie.the
to repair the losses experienced by this liquid in its action
upon the organs nourished by it.   But how is this hcema-
tosis, or  transformation of chyle into  blood, effected ?
   We have already said, that these two liquids are much
alike, and  that by the action of the  air  upon the chyle,
this resemblance becomes yet closer,  because  the color of
this liquid is rendered very analogous to that of the blood.
From which it might be concluded, that a part  of the
modifications necessary  to change the chyle  into blood,
take  place in the interior  part of the lungs,  and by the
act of respiration.
   Still there exists between  these two liquids an import-
ant difference, not to be thus accounted  for.   The  glo-
bules of the chyle do not appear to be contained in  a 
142
ANATOMY AND PHYSIOLOGY.
colored  vesicle,  like those of  the  blood, and therefore
the question  arises,  where  are  these  latter globules
formed ?
  This  question is not yet completely determined ;  but
from some acknowledged facts, the  liver would seem to
be the agent in effecting this  important change.
               URINARY  SECRETION.

   One portion of the foreign substances absorbed by the
human body and of the materials eliminated from the or-
gans  by the exercise of nutrition, are expelled from the
economy, either by the respiration, pulmonary exhalation,
and cutaneous transpiration, or by the secretion from the
surface  of  the  intestines and  the  other  mucous  mem-
branes ;  but substances, which  are useless or injurious to
the economy, may be rejected by another  way, the urin-
ary excretion.
 Uparatusap"   This function is that of the kidneys, which are
two voluminous glands situated  in the abdomen, on either
side of the vertebral column, between the  muscles of the
lumbar region of the back and  the peritoneum, and ordi-
narily surrounded  by much fat; their  color is reddish
brown, and their form like  that of a hancot or  kidney-
bean.  The panenchyma appears to be formed of two
substances;  one superficial, called the cortical or glan-
dular ; the other interior, named  tubular or  mamellated.
The  cortical substance  is  formed of  extremely  small
granulations, and a multitude of capillary canals twisted 
URINARY SECRETION.
143
upon themselves, and united in clusters ; the mamellated
is composed  of canals, which spring  from the cortical,
and, converging towards the middle of the  interior border
of the gland,  form  by their union a certain  number of
cones, with a  rounded base, surrounded by the cortical
layer.   These  canals  all empty at the summit of these
pyramids into other  and greater ducts called  the calices,
which in their  turn supply the pelvis, a small membrane-
ous pouch situated in  the fissure of the internal  border
of the kidneys.
  These glands receive a considerable quantity of blood
from a large artery, which ramifies upon the cortical sub-
stance, where is effected the secretion of a peculiar liquid,
the urine.
  This  liquid  descends  by the  canals composing  the
mamellated substance, and  by the calices  to  the  pelvis,
and  thence passes into the  bladder through a long mem-
braneous tube of the size of a writing quill, which passes
transversely from the pelvis  to the bladder, and is called
the ureter.   The bladder is  a conical  pouch, which fulfils
the functions of a reservoir  for the  urine, and is situated
at the inferior part of  the abdomen, behind  the anterior
portion of the pelvis, called  the  arch of the pubis.   It is
formed of  a mucous  membrane,  surrounded  by fleshy
fibres, and continues inferiorly with a narrow canal, open-
ing outwards, and which is  called  the urethra.
  The urine is  a yellowish and acid liquid, which,  urine.
in man, is composed  in the normal  state of  nearly ninety-
three hundredths of water, three hundredths of a peculiar
matter, called urea,  of a thousandth of uric and a small
quantity  of lactic acid, and  of several  salts (the chloride
of sodium or marine salt,  phosphate of lime, &c.)  In 
144
ANATOMY AND PHYSIOLOGY.
the carnivorous  mammiferae  its chemical composition is
nearly the same as in  man, except that we  do not find
the uric acid ; but in young children and herbivorous an-
imals, there is a very peculiar substance contained in it,
namely, the hypo-uric  acid ;  and in birds, as well as in
most reptiles, (lizards, serpents, &c.) it scarcely contains
any thing but uric acid ; finally in frogs and turtles, we
find both urea and albumen:  its composition appears to
be nearly the same in  fishes, but in insects there is uric
acid.   In certain  diseases, its  composition, however, is
considerably changed.
 SoUur1n°efthe  The rapidity, with  which  fluids introduced
into the stomach pass into  the bladder  and are expelled
by the urinary  passages, is very great.  Every one has
made the remark,  and the  experiments upon living ani-
mals also prove it.   But yet there  exists no  direct com-
munication  between these  two organs, and the liquids
can only pass to the bladder after having been absorbed,
mingled with the  mass of the  blood, thus conveyed  to
the substance of the kidneys, and separated by the se-
cretory exercise, of which these glands are the seat.
  It is evidently from  the  blood that the kidneys derive
all the aqueous portion of the urine; and if  certain sub-
stances, easily recognised,  (such as rhubarb, or the yel-
low cyanuret of potassium or iron,) be introduced into
the current  of the circulation, (either by injection or ab-
sorption,) they  are  soon found to be  expelled in the
urine.
  The blood, then, furnishes to the kidneys the materials
necessary to form  the urine ; and the knowledge of this
fact must naturally  lead physiologists  to  inquire if the
several principles  contained in  the latter existed, com- 
URINARY SECRETION.
145
pletely formed, in the blood, and were merely separated
by the  action of the kidneys, or whether these organs
produced them, by their action upon other substances con-
tained in the blood.
   Water and most of the matters expelled by the urinary
passages, exist in  quantities  more or less appreciable in
the blood ;  but, under  ordinary  circumstances, chemical
analysis does not reveal to us the presence of urea and
the other principles essentially characterizing the urinary
secretion.   It might  therefore be supposed, that these
materials were formed directly by the kidneys ;  but  it is
not so ;  these organs only separate them from the blood
gradually,  as they appear ; and an  infallible  proof  will
be found in the extraction  of the  kidneys in  the  living
animal; for then, the urinary secretion being interrupted,
we find  urea in the blood.
   Therefore it is a legitimate inference, that the urinary
glands  actually derive  from  this liquid the substances
which compose the urine, and that they find them ready
formed.
   But different circumstances influence the ac- ^fS^ngthl
tivity of this function, and may modify both the secretion"
mass of  the liquids expelled by the urinary passages, and
the quantity of solid materials, separated from the blood
by the action of the kidneys,  and held in solution by the
aqueous  part of the urine.
   The quantity of water expelled by the urinary secre-
tion depends, in a great measure, upon that of the fluids
taken into the stomach.
   Water introduced into  the  mass of the  blood by ab-
sorption  separates from it more  or less  rapidly, so that
after a certain time the  equilibrium is established in the
                   19 
146
ANATOMY AND PHYSIOLOGY.
economy, however great the quantity of fluids introduced
into the stomach.   This liquid escapes from  our bodies
in two distinct ways, namely, by pulmonary and cutane-
ous exhalation, and  by the urinary secretion; and these
two functions are in a measure mutually dependent, and
the  mass of fluids  in  circulation remaining  the same,
every thing which tends  to  diminish  the  one, tends  to
augment the other.
   For example, the action of heat upon the body tends
to augment the transpiration, and, consequently, to di-
minish the urinary secretion : thus  the  latter  function is
more active in winter, than in  summer,1 and  if any one
take a considerable quantity of drink, he can almost vol-
untarily determine its expulsion, by one or other of these
means, according as he is placed in circumstances favor-
able for transpiration, or the urinary secretion.
   The quantity of solid substance expelled by the kid-
neys, and held in solution by the aqueous portion of the
urine, depends, in a great measure, upon the  nature and
abundance of the aliments taken.
   It  has  been proved  by M. Chossat, that when nour-
ished upon  the same  aliments, the only variation being
in quantity, the secretion of urea and  the other different
principles, with the  exception of water, expelled  by the
kidneys,  varies in  the same proportion.   It  diminishes
with rigorous  abstinence, and augments with the increase
in the quantity of food, always provided this quantity be
not too great for digestion.

  1 The curious experiments of M. Chossat demonstrate, that in the cold
season the mass of urine surpasses that of the fluids taken into the sto-
mach.  In the months of spring, when the temperature is mild,  this rela-
tion is sensibly diminished, and in the hot season the proportion of the
urine to the drink is only about nine tenths. 
URINARY SECRETION.
147
   This physiologist has also proved, that the secretion of
these matters increases  in  the  ratio of the quantity of
animalized  substances taken, that is, substances which
contain a  considerable  proportion of azote.  Thus by
nourishing himself upon bread alone, or upon flesh alone,
he found, that for an equal weight of food  (abstracting
the  water contained),  the quantity of solid  principles
expelled under the form  of urine was four times as great
in the latter case, as in the former.
   If we compare the quantity of carbon, azote, hydro-
gen, and oxygen, which enter  into  the  composition of
the  aliments employed  by man, with that of the  same
elements  expelled under various  forms,  either by  the
lungs and skin,  or by the kidneys, we find almost all the
carbon, thus introduced  into the body, escapes from the
lungs under the form of carbonic acid, while  the  azote
is almost entirely expelled  by the urine, as  urea, uric
acid, &c.
   But the state of  the  animal's  system  also exercises
great influence upon the results  of the urinary  secretion ;
as every thing which tends  to weaken, appears to retard
this  secretion, and to diminish the exhalation of carbonic
acid by the respiration.
   The urine sometimes deposits in the interior nri2^lc"un,jj
of the urinary passages various substances, which may be
held in  solution,  but which when  deposited as solids are
styled gravel and urinary calculi.
   The gravel  is  almost  always formed of uric acid, and
depends upon its too great secretion ; thus this  malady is
increased  by every thing which tends to augment  the
proportion  of solid substances held  in solution by  the
urine, as the diet of the  animal, the  too constrained  use 
148
ANATOMY AND PHYSIOLOGY.
 of aqueous drinks, &c.  In  general this deposit forms in
 the kidneys and is passed out with the urine.
   The urinary calculi are  larger concretions, which also
 sometimes form in the kidneys, but more  generally are
 developed  in  the bladder  where  they reside.   They
 gradually enlarge by the  addition of new matter from
 the  urine, and owing to their formation present concen-
 tric layers,  more or less distinct.
   The substances entering into their  formation are very
 various.  Some are always  existent in the urine, but in
 quantities so small, that they are ordinarily held in solu-
 tion.  Others are  produced,  or rendered insoluble  by the
 chemical action experienced  by the  urine when long ex-
 posed  to  the  air,  or  confined  in the  bladder.  Finally,
 others are  the result  of an  abnormal  action of the se-
 cretory organ  itself.
   The first  are of uric acid,  the second urate of ammo-
 nia, the phosphate ammoniaco-magnesian, the phosphate
 of lime, the  third the oxalate of lime, the cystic oxide, etc.
   Calculi of the first class are the most common, and it
 often happens that their presence  in  the  bladder  deter-
 mines the deposition of the salts, that we have ranged in
 the second category.   It is rare to see these latter sub-
 stances form the nucleus of  a  calculus;  but nothing  is
 more common, than to find a nucleus of uric acid or oxa-
late of lime  encrusted with earthy phosphate.

                       REVIEW.
   Having now gone over the different series of phenom-
 ena, by means of which the nutrition of the body of ani-
 mals is  effected, to embrace at a glance the operation of
 all these functions, it is thought proper to  give their enu- 
URINARY SECRETION.
149
meration in an order varying from that adopted in  their
study.
  It has been shown, that all living beings must contin-
ually draw to the interior of their bodies water, oxygen,
and  various other alimentary matters  derived from the
exterior world, and deposit  these  new materials in the
tissue of their organs.
  The name of absorption has been given to this passage
from without inwards, and  to  the  combination of the
materials, thus sucked in  by the living organs with the
mass of the nutritive fluid.
  In plants, all nutritive substances are absorbed at once,
and  penetrate directly into the parenchyma of the organs,
without having undergone any previous preparation.  In
animals, certain substances,  as water and the oxygen of
the air, are absorbed in the  same  manner,  either by the
skin, or by the internal  tegumentary surface lining the
aerial and digestive passages;  but with most  nutritive
materials, it is quite otherwise, and the food cannot serve
for the support of the body,  and penetrate into the inte-
rior  of the organs, until it has first been transformed into
a peculiar liquid, called  chyle,  a  transformation, which
constitutes the phenomena of digestion.
  The chyle, absorbed by the lymphatic vessels, mingles
with the blood, and furnishes the materials of which this
liquid is composed.
  The blood circulates in all parts, and conveys to them
the  materials necessary for their support.   By the aid of
the  nutritive principles, which are  furnished them by this
liquid, the living tissues continually incorporate with
their own substance new particles, and while this  exer-
cise  of assimilation is going on, they abandon other mole- 
150
ANATOMY AND PHYSIOLOGY.
cules,  which entered  into  their composition, and  the
renewal of which has therefore become necessary.
  This continual movement of the composition and de-
composition of  the solid  parts  of the  body,  constitutes
the exercise of the function of nutrition.   When the quan-
tity of foreign materials, thus assimilated to the substance
of the organs,  exceeds that  of the matters eliminated
from these same organs, the body increases ; in the oppo-
site case,  it becomes lean; and if these two phenomena
are  equally active, the  weight of the animal remains sta-
tionary, although the materials of which its body is com-
posed are unceasingly renewed.
  The excrementitial matters, separated  from  the sub-
stance of  the living organs by the exercise of nutrition,
must  be  thrown out, — and this  actually takes place.
They are at first  mingled with the blood, which  con-
veys them along with it  far from the  parts where they
were detached, and in its turn  this  liquid is freed from
them, either by the simple exhalation which takes place
from all tegumentary surfaces, exterior  as well as inte-
rior, or by the secretion from the glands, the  parenchyma
of which it traverses.
  The water thus expelled from the body, escapes prin-
cipally by the insensible transpiration of the lungs and
of the skin,  and by the urinary secretion.
  The greater  part of  the azoted principles and  of  the
materials  not volatile, are in general excreted by  the
kidneys.
  On the contrary, from the lungs are  exhaled  carbonic
acid and the other volatile principles which may be found
mingled with the blood.
  Respiration is consequently, at the same time a func- 
FUNCTIONS OF RELATION.
151
tion of assimilation and of excretion, as  it  serves as a
means for the entrance of the oxygen necessary to the
support of life,  and for the exhalation of the  carbonic
acid  produced  by  the nutritive  decomposition of the
organs.
  With regard  to the nature of the movement of nutri-
tion, of  which  all living parts are the seat, we again re-
peat, nothing certain is known: we can  only presume,
that it must resemble the secretory exercise, and that it
must  depend upon the action of an analogous  cause,
which cause appears to be  the nervous  influence, and
which seems to have  a  great  analogy  to the  physical
force  which produces  the electro-chemical  phenomena.
Recent experiments by M. Becquerel upon the influence
of electricity on the  vegetation of plants, come to the
support of this  opinion.
             FUNCTIONS OF  RELATION.

  In  the  enumeration of  the different  faculties, with
which animals are endowed, we found that  some were
exclusively destined to confirm the existence  of these
beings, while others served to  convey to  them a knowl-
edge of surrounding objects.   The former constitute the
functions of nutrition, which we have already  studied;
the latter, the functions of relation, with which we are
now to be occupied.
  If we examine what takes place in an animal contractility.
of the simplest structure and  most limited powers, the
first thing we notice is its motion, and  that  the move- 
152
ANATOMY AND PHYSIOLOGY.
ments which it executes are determined and directed by
a  cause acting internally.   Among these movements,
some are repeated in  the same manner, whatever be the
circumstances in which the  animal is placed, and  over
which it has no actual control.
  volition.   But there are others, which vary  according to
the wants of the animal, and are  under the direction of
an intelligent power,  known as volition.
   These two orders of phenomena constitute two of the
most important functions of relation, to wit: contractility
or the  faculty of  executing spontaneous  movements;
and  volition, or the faculty of exciting contractility, and
varying its effects  with a view of arriving at  a result
foreseen by the animal.
 sensation.  There is yet another property inherent in all
animated beings, and which  is still more remarkable ;  it
is sensation, or the faculty of receiving  impressions from
external objects, and  being conscious of them.
 instinct.   These three faculties are common  to  all  ani-
mals, but they are not the only ones observed.  It is re-
marked, that in all there exists an inward  power, which
causes them to perform certain acts useful for  their  pre-
servation, but the result of which they cannot certainly
presage, and  the cause of which depends  upon no appa-
rent need.   Thus a multitude of animals construct with
the most admirable art dwellings, destined to lodge their
offspring, and calculated to supply all  their wants, and
they always do this in the same manner,  and with the
same skill, even  when they have  been  separated  from
others of their kind  fronx birth,  and have never  seen
analogous labors.   Others at a determinate season of the
year emigrate to far  countries,  where  the climate  will 
FUNCTIONS OF RELATION.
153
 be more  favorable to them, and they  direct themselves
 thitherward as certainly, as if the end of their  voyage
 were before their eyes.
   The name instinct has been given to the cause, which
 thus constrains animals to execute  certain determinate
 acts, which  are neither the effect of imitation, nor yet
 the  result of reasoning.  These inclinations vary, so to
 speak, in every species of animals, and the phenomena,
 which result from them, are sometimes extremely simple,
 and sometimes of an astonishing complication.
   Other  animals  more highly privileged, enjoy intelligence.
 the  possession of  the  intellectual faculties, or  the power
 of recalling to the mind the ideas  primarily produced by
 the  sensations, of comparing them, of drawing from them
 general ideas and deducing motives of conduct.
   Finally, there are also some  animated beings, Expression.
 which enjoy the faculty of imparting  their  ideas to their
 fellows, either by certain movements, or by  the produc-
 tion of various sounds.
   The various phenomena, by  which animals are  put in
 relation with  surrounding  objects,  may therefore, as we
 have seen, be referred to six principal faculties ;  sensation,
 contractility, volition, instinct, intelligence, and expression.
 The four first exist in  all animals, the two latter only in a
 small number,  and the manner  in which they are execut-
 ed varies almost to infinity.
   In some animals of very simple structure, the polypi
 for instance,  the various faculties of relative life are not
 the appropriation of any particular organ : each separate
portion  can feel and move without the concurrence of
another portion; but in man and the immense majority
of animals, the exercise of all these functions is dependent
                  20 
154
ANATOxMY AND PHYSIOLOGY.
upon the action of a determinate part of the body, which
is called the nervous system.

                    NERVOUS SYSTEM.
Nervous tissues.   This system is formed of a peculiar substance,
soft and pulpy, which is almost fluid in the early periods
of life, but which acquires consistence as man approaches
the adult age.
  It is worthy of observation, that in this respect, the in-
ferior animals resemble more perfect beings whose devel-
opment is not completed.   In  frogs the cerebral pulp
affords no more consistence than in the human foetus, and
in crabs it is almost liquid.   There is in nature a tendency
of which we shall often have occasion to speak, viz., that
of causing the superior order of  animals to pass through
transitory stages, analogous to the state which is perma-
nent for beings of a less perfect structure.
  The aspect of this substance, which is named the ner-
vous tissue, varies greatly; sometimes it is  white, at others
gray and ashy ; sometimes  it is  gathered into consider-
able masses, at others it forms long ramified cords.   The
latter organs  are named nerves, and the former ganglions
or nervous centres, for they serve as a point  of union for
all the  filaments in question.
  In man, and all  the animals  nearly allied to  him, the
nervous apparatus  is composed of two parts, called ner-
vous system of animal life or cerebrospinal,  and the ner-
vous system of organic life or ganglionary ;  and each of
these systems, in its turn, is composed of  two parts;  one
central, formed of  nervous masses more or less consider-
able, the other a periphery,  formed of nerves going from
these centres to various parts of the body.
Encephalon.    The central portion of the cerebro-spinal ner- 
FUNCTIONS OF RELATION.
155
vous system is often designated as the cerebro-spinal axis,
or the encephalon.   It is essentially composed of the brain,
cerebellum and spinal marrow, and it is lodged in a bony
sheath formed by the  cranium  and vertebral column, or
spine.
   The cavity of the cranium occupies all the su-  Parts protect-
            J                    l               ing the eiicc-
perior and posterior part of the head.  It is of pl,aIon'
an oval form, and presents, on its inferior surface, a great
number of holes, which give passage to the nerves pass-
ing out, and to the blood-vessels which serve for the nu-
trition of the parts contained in its interior.  Lastly, in  the
point where the head  articulates with the vertebral  col-
umn on which it rests, there exists a great opening called
the occipital hole, through which the  cavity of the cranium
is continuous with a  canal, which extends the w7hole
length of the median line of the  back.
   This canal is formed by a succession of bony    ZTutm!
rings, called  vertebrce  (fig.  26), which  joined   Fig. 26.'
together in a solid manner, constitute a kind  of
stalk, which occupies the whole length  of the
body, and is called the spinal or vertebral col-
umn  (fig. 27).  On each  side  there  exists  a
series of holes, through which the nerves pass
to the different parts of the body.
   Several membranes also surround the  ence-
phalon, and serve to fix or to protect this organ,
whose  structure is  very delicate, and import-
ance very great.
  The  first of these tunics is  called  the ™'trear.
dura mater; it is a fibrous membrane,  firm, thick,
whitish and moist,  which  adheres by  several
points of its exterior surface, to the walls of the
  1 Fig. 26.  The superior surface of one of the vertebrae of the back.  Fig.
27, a profile view of the vertebral column.
Fig. 27. 
156           ANATOMY AND PHYSIOLOGY.

cranium and vertebral canal, and  forms around  the ner-
vous system a very resisting sheath.   Upon its interior
surface are many folds, which bury themselves in furrows,
more or less deep, of the encephalic nervous mass, and
form a kind of division, which prevents these parts from
being displaced, and sustains them  so  that  they do not
press against each other in any position of the  body.
There also exist  between its internal  and external sur-
face, very large venous canals, which are called sinuses of
the dura mater, and which serve as reservoirs  for the blood
coming from the different parts of the encephalon.
  Arachnoid.   Within the dura mater we find a  second cov-
ering, the arachnoid, so called from its tenacity and trans-
parence,  which have caused it to be compared to  a spi-
der's web.  It belongs to the class of serous membranes,
and represents  a sac without an opening doubled  upon
itself, which envelops the  encephalon, and lines the walls
of the cavity of the dura mater, in the same way  that the
pleura envelops the lungs, and the peritoneum  the  intes-
tines.  Its interior surface, every where in   contact with
itself, is lubricated by a serous humor, and its internal
plate penetrates into the  different  cavities, of which we
shall hereafter have occasion to  speak, in the interior of
the brain.  Its principal use is to furnish a  liquid  which
bathes this organ and facilitates its  movements.
  pia mater.   Finally, we find  beneath the arachnoid a third
cellular membrane, which is wanting in certain parts, and
which is called the pia mater.  It is not a membrane, pro-
perly so called, but a cellular layer destitute of consist-
ence, in which are ramified and interlaced, in a thousand
different directions, a multitude of blood vessels, more or
less fine and tortuous, which come from the encephalon, 
FUNCTIONS OF RELATION.
157
Fiff. 28.
or are scattered in  its substance;  the circulation of the
blood in the encephalon being in a very peculiar manner.
The arteries before penetrating into this organ, the texture
of which is very delicate, are reduced to capillary ves-
sels, the purpose of which is  to moderate  the force with
which the blood reaches the organ.
                       The cerebro-spinal  axis,  Encephalon.
                    which is  protected by  these different
                    envelopes,  is  composed,  as  before
                    mentioned, of several distinct organs;
                    but  all  these  parts  are intimately
                    united together, and may be consid-
                    ered as a continuation of each other.
                    Its anterior  or  superior  part is very
                    voluminous, and occupies the interior
                    of the   cranium:  to  this  belongs
                    the special  name of encephalon.   It
                    is divided into two parts, the  brain
                    (cerebrum), and the cerebellum, both
                  33 continuous  inferiorly  with  a  large
                    nervous  cord  lodged  in the  spinal
                    column,  and called the spinal mar-
                  \ row.
                       The brain (fig. 28,  a, and fig. 29,
                  * A, B, C,)  is  the most  voluminous
                    portion of the  encephalon ;  it occu-
                    pies all the superior part of the cra-
                    nium, from the forehead  to the occi-
                    put.   Its form is oval, with the large
  1 Cerebro-spinal system seen on its anterior face (the nerves being divided
at a short distance from their origin), — a, brain, — b, anterior lobe  of the
left hemisphere of the brain, — c, median lobe, — d, posterior lobe, almost 
158
ANATOMY AND PHYSIOLOGY.
extremity behind, its superior face is quite a regular arch,
and at the sides it  is a  little compressed, while below it
              Fig.   29.1
A         f             B
entirely concealed by the  cerebellum, — e, cerebellum,—/', medulla ob-
longata,—/, spinal marrow, — 1, nerves of the  first pair, or olfactory,—
2, optic, or nerves of the second pair, — 3, nerves of the third pair, which
originate from behind the interlacing of  the optic nerves in front of the
pons varolii, and above the peduncles of the brain, — 4, nerves of the fourth
pair, —5, trifacial or nerves of the fifth  pair, — 6, nerves of  the sixth pair
lying upon the pons varolii, — 7, facial or  nerves of  the seventh pair, and
acoustic or nerves of eighth pair, — 9, glossopharyngeal, or nerves of the
ninth pair, — 10, pneumogastric, or nerves of the tenth pair,— 11, nerves
of the eleventh and  twelfth pairs, —13, suboccipital, or nerves of the thir-
teenth pair, — 14, 15, 16, three first  pairs  of cervical nerves, — g, cervical
nerves forming the brachial plexus, — 25, a pair of the dorsal nerves, — 33,
a pair of the lumbar nerves, — h, lumbar  and  sacral nerves forming the
plexus, from which arise the nerves  of the lower  extremities,—i, and j,
termination of the spinal marrow called the cauda equina, — k, great sciatic
nerve going to the lower extremity.
  1  Vertical section of the cerebrum,  cerebellum, and  medulla oblongata ; — 
FUNCTIONS OF RELATION.
159
is somewhat flattened.   At first, we distinguish two late-
ral halves, named hemispheres of the brain, and separated
by a deep fissure, in which is  buried a  partition, formed
by a fold of the dura mater, and called  from its form the
cerebral falx.  From before backwards, this fissure divides
the brain in its whole extent; it  does  not however ex-
tend completely  through from above downward, but is
bounded inferiorly by a  medullary plate,  which extends
from one hemisphere to the other, and  is called  the cor-
pus callosum  (fig. 29, f).  The surface  of the hemi-
sphere  is  divided  by a great number of tortuous and
irregular furrows  of various depths,  which separate  the
rounded  eminences  upon  its  exterior,  convoluted upon
themselves, and having  some resemblance to the folds of
the small intestine, in the abdomen.   These eminences
are called the convolutions  of the brain ; and the furrows,
which  separate them, and  lodge the folds of the internal
plate of the arachnoid, are  called anfractuosities.  They


A, anterior lobe of the brain, — B, median lobe,— C, posterior lobe, —JD,
cerebellum, — E, spinal marrow, —/, section of the corpus callosum, situ-
ated at the bottom of the fissure which separates the two  hemispheres of
the brain;  below this transverse band of white matter are found the lateral
ventricles of the brain, —g, optic lobes concealed below the anterior face
of the brain, — 1, olfactory nerves, —2, the eye, in which terminates the
optic nerve, the root of which may be followed upon the sides of the annular
protuberance to the optic lobes;  behind the eye we see the nerve of the
third pair, —4, nerve of the fourth pair, which is distributed  like the pre-
ceding to  the muscles of the eye, — 5, superior  maxillary branch of the
nerve of the fifth pair, —5', ophthalmic  branch of the same pair, — 5", in-
ferior maxillary branch  of the  same nerve, — 6, nerve of the sixth pair
going to the muscles of the eye, — 7, facial nerve, below the origin of this
nerve we see a section of the acoustic, — 9, glosso-pharyngeal  or nerve of
the  ninth  pair, —10,  pneumogastric, —11, hypoglossal, or nerve of the
eleventh pair, — 12, spinal or nerve of the twelfth pair, —14,  and 15, cer-
vical nerves. 
160
ANATOMY AND PHYSIOLOGY.
 vary in  depth,  and it  is worthy of remark, that in the
 child and in most animals, even those nearest to man, the
 convolutions  are  but  little developed.  On  the  inferior
 face of the brain we find in each hemisphere three lobes,
 separated  by transverse furrows, and designated as the
 anterior, median, and  posterior  lobes;  we  also observe
 in this part of the  brain  two round eminences, placed
 near the median line  (mamillary eminences),  and  two
 large peduncles which  seem to issue from the substance
 of this organ to continue with the spinal  marrow (com-
 missures or penduncles of the brain).   Also from this part
 of the brain issue the  nerves, to  which this  viscus  gives
 origin.
   The surface of the brain is almost entirely formed of
 a gray nervous substance; but its interior is  composed of
 a white  substance.   When  this  organ  is cut  into, we
 find that there exist in  its interior several cavities, which
 communicate externally, and which are called the ventri-
 cles of the brain.  (Fig. 29,y).
  cerebellum.   The cerebellum is  placed  beneath the poste-
 rior part  of the brain (fig. 29, D, and fig. 28, e,) and has
 not one third the size of  this  organ, even  in the adult,
 where it is larger in proportion than in the infant.   It is
divided like the brain, into  two  hemispheres, or  lateral
lobes, separated by a fissure, and a median lobe, situated
 behind and below, in  a depression  already mentioned.
The surface of the hemispheres and of the median  lobe
is formed of a gray material, and presents no convolution,
but a great number of furrows nearly straight, and placed
parallel one by the side of the other, so as to  divide  this
organ into a multitude  of plates, arranged like the leaves
of a book.   Inferiorly the brain  is continuous with  the 
FUNCTIONS OF RELATION.
161
spinal marrow, by means of two short thick peduncles,
and at the same point, it surrounds this latter organ with
a band of white  substance, which extends transversely
from  one hemisphere to the other, passing in front of the
spinal marrow, with which it is closely united,  and which
bears the name of annular protuberance, or pons Varolii;
so called in honor of a celebrated anatomist, Varolius.
   When the  posterior lobes of the brain are oPtic iobes.
raised, there may be seen  between  this organ  and the
cerebellum, four  small round eminences, placed a pair
on either side of the median line (fig. 29, g).  They are
raised upon the superior face of the  medullary prolonga-
tions going from the  brain  to  the  spinal marrow, and
constitute what anatomists call the optic lobes, or  tuber-
cula quadrigemina, to be noticed hereafter.
   The spinal marrow (fig. 28,/, and 29, E,) is  JfsS^.
in some sort a prolongation of the  cerebrum and cerebel-
lum.   It has the form of a thick  cord, and presents in
front, as well as behind, a median and. longitudinal  fur-
row, which divides it into  two lateral and symmetrical
halves.   At its superior extremity (to which anatomists
have given the name of medulla oblongata), several en-
largements  may  be observed, called olivary, pyramidal,
and restiform  bodies, and from either side of which issue
a great number of nerves, at first directed outward but
afterwards descending more obliquely, so that  the  spinal
marrow appears  to  terminate by dividing into  a great
number of longitudinal filaments, arranged as the hairs in
the tail of a horse, (fig. 28, j), a resemblance, which has
secured to  this part the name of the  object to which it
has been compared.   On a level with the origin of the
nerves distributed to the thoracic members, the  spinal
                   21 
162
ANATOMY AND PHYSIOLOGY.
marrow presents an evident enlargement; afterwards  it
contracts, and again enlarges in volume at the origin  of
the nerves supplying the abdominal muscles;  its lower
extremity is very small, and is found toward the superior
part of the lumbar region of the vertebral column.
   The  spinal marrow is composed, like the brain and
cerebellum,  of two  medullary substances different  in
color;  but here the  gray matter, in place of being  upon
the surface, occupies the interior of  the  organ, and  is
covered by the white  material.  There  is no pia mater
around the spinal marrow, and the sheath formed by the
dura mater, is not entirely occupied by this organ, but is
distended by a  considerable quantity of liquid, in the
midst of which it is suspended ; an arrangement admi-
rably adapted to preserve it from  the  pressures  or  com-
motions, which might result  from  too violent movements
of the  vertebral column, or  from  any other  cause, and
which would produce  upon this part of the nervous sys-
tem consequences more  serious than upon the brain.
 enceephafonhe  We have said, that the substance forming the
cerebro-spinal axis was soft and pulpy; yet in the white
matter fibres may be distinguished, and the study of their
course  leads to the explanation of many remarkable phe-
nomena.
   The spinal marrow presents, then,  two halves, united
by  bands,  formed  principally of  transverse  medullary
fibres ; on either side we find  also, in the  white sub-
stance of this organ, a great number of  longitudinal fibres,
which, at the superior part,  are united in six  principal
portions.  Four  of  these  portions occupy the anterior
face of  the medulla oblongata; they constitute the en-
largements known as  the anterior  pyramids, and olivary 
                FUNCTIONS OF RELATION.            \QQ
bodies, and they penetrate into the brain.   The fibres
of the pyramids present a very remarkable peculiarity ;
those of the right side branch to the left, and those on
the left to the  right: not  till after this  interlacing are
they buried in  the annular protuberance, and,  continuing
their course forward they constitute the peduncles of the
brain.   These  fibres afterwards diverge  and  expand in
the inferior, anterior and superior convolutions of the
anterior and median lobes of the brain.   The longitudi-
nal fibres from  the olivary  eminences ascend, like those
of the pyramidal, across the annular protuberance,  and
go to form the  posterior and internal part of  the pedun-
cles of the brain; they  traverse, like those of the pyra-
midal  bodies, various masses  of the gray substance, in-
crease in volume and number, and  by following different
directions form several parts of the brain, as the  thalami
of  the optic nerves, and  the corpora striata;  finally,
they expand into the convolutions, the  entire mass of
which  constitutes the cerebral  hemispheres ;  by the  in-
tervention of other transverse fibres the two halves of the
brain communicate  together, and these fibres constitute
the corpus callosum  already mentioned, as well as several
other  transverse  bands, designated by anatomists under
the general name of commissures.
  The longitudinal  fibres of the  posterior pyramids of
the spinal marrow are united to some fibres coming from
the neighboring parts of the medulla oblongata, and thus
constitute the peduncle of  the cerebellum ;  they plunge
to the very centre of the corresponding hemisphere of this
organ,  and send to its circumference a multitude of plates
which  subdivide  and form  by their ramifications, as it
were, branches enveloped in the gray material, and called 
 Ig4           ANATOMY AND PHYSIOLOGY.

 by some anatomists the arbor  vitce (fig. 29, D).   The
 communication of the two hemispheres of the cerebellum
 by means of transverse fibres may also be seen, a part of
 which surround the  medulla oblongata in  front and  form
 the annular protuberance.
  Nerves.    The nerves, which spring from the  encephalon,
 and which establish  the communication between this sys-
 tem and the different  parts of the body,  are  in  number
 forty-three pairs  (fig. 28, and  fig. 29).   They all arise
 from the spinal marrow or base of the brain, and are dis-
 tinguished, from their  position, by regular numbers from
 before backward.  Most of them are at first  formed by
 several roots, or collections of  isolated fibres,  and present
 near their origin an  enlargement called a ganglion (fig.
  Fig. 30.1  ^O, c).   The  twelve first pairs spring from
            the encephalon, and issue from the skull by
          7  the various  holes  in the  base.   The  suc-
            ceeding  thirty-one pairs arise  from that por-
         "c  tion of the spinal  marrow which is contained
            in  the vertebral canal,  and issue  from this
          e
            osseous  covering  by holes situated on each
      d f   side, between the  vertebrae. (Fig. 27.)
   Finally, these nerves, with  very few exceptions, soon
 divide into a multitude  of  branches, which in their turn
 are subdivided  into  twigs, and terminated by filaments
 extremely  tenacious, in the substance of the  different

  1 Section of the spinal marrow to show  the disposition  of the nerves
originating from it, — a, spinal marrow, — b, the anterior root of one of the
 spinal nerves, — c, ganglion, situated in the course of this root, — d, posterior
root of the same nerve, united to the anterior root beyond the ganglion,—
e, common trunk formed by the union of  these two roots, —/, small branch
anastomosing with the great sympathetic nerve.
 
FUNCTIONS OF RELATION.
165
organs.   Often, too, some of these nervous branches are
united, and form an anastomosis1 or a plexus.2
   All the spinal nerves originate by two roots, composed
of several fasciculi  of  fibres ; one  from the anterior, the
other from the  posterior part of the  spinal marrow (fig.
30).
   The ganglionic nervous system, called also the  Gsayn|etnic
great sympathetic, or nervous system of the organic life, is
composed of  a  certain number  of small nervous masses,
perfectly distinct, but  united to each other by medullary
cords and various nerves, which anastomose with those of
the cerebro-spinal system, or are distributed to the neigh-
boring organs.   These nervous centres are called gang-
lions ; they are found  in the head, neck,  thorax, and ab-
domen.   Most  of them  are placed symmetrically upon
either side of the median line  in  front of the vertebral
column, and  thus form a double chain from the head to
the pelvis; but they are  also found in other  parts,  near
the heart and in the neighborhood of the  stomach.
   The  nerves  of  the cerebro-spinal system  go  to  the
organs of the  senses,  to  the skin,  muscles,  &c.;  those
which make a part of  the ganglionic system are  distrib-
uted  to the lungs, heart, stomach,  intestines, and  sheaths
of the blood  vessels.   In a word the former belong spe-
cially to the organs of relation, the latter to  the organs
of nutrition.

  1 The nerves, having been  regarded by some anatomists as canals to con-
duct the nervous fluid, the name of anastomosis has been given to the
union of their branches, or twigs ; this word, as we have already said, sig-
nifies really an emptying or a communication between two vessels.
  2 Plexus (from plecto, I interlace) is the name given to a kind of union
of several  nerves or vessels.  The principal nervous plexi are those formed
by the nerves of the limbs, soon after issuing from the vertebral column.
 Fig. 28, g and h.) 
IQQ           ANATOMY AND PHYSIOLOGY.

  Such are the various parts which compose  the nervous
apparatus of man ; let  us now see its  uses, beginning
with the study of sensation.

                      SENSATION.
  Sensation we have defined to be the faculty of receiving
impressions, and being conscious of them.  It belongs to
all animals, but the degree in which it is developed varies
with each of them.  As we ascend  in the scale of ani-
mal life, and approach  man,  the sensations are much
more varied.   The  animal acquires the power of taking
cognizance of a greater number of the  properties  pos-
sessed  by surrounding objects, and of better appreciating
slight  shades of difference.   The  impressions produced
become more lively, and as the faculty of sensation is
thus perfected, the  structure of the organs of the life of
relation, become more  complicated; for  here, as well as
in all the other  functions, by the  division  of labor does
nature  obtain increasingly perfect results.
  Wherever the sensations produced by external objects
are  a little varied, there exists a distinct nervous system,
and upon its  action depends the faculty of  perception.
Its structure is at first very simple, and then all the parts
composing it appear to fulfil nearly the  same function.
In the  earth worm, for example, it is a knotty cord  ex-
tended the length  of the body, all  the  parts of  which
possess the same properties ; for if the  animal be divided
transversely into several sections, each of these fragments
will continue to move and feel as before  ; but in  beings
of a more complicated  organization,  and  more  perfect
faculties, this apparatus is composed, as in man, of sev-
eral dissimilar parts, each of which then acts in a man- 
                FUNCTIONS OF RELATION.             -[Q>J

ner  different from the rest,  and discharges special func-
tions.
   The most general phenomena, of those de-  sense of tact.
pendent upon the action of the nervous  system, is the
perception of a sensation from the contact of a material
object with one of the organs of the animal.  These are
not the sole sensations that may be experienced, and to
be more precise in our language, we must distinguish by
a particular name the faculty on which they depend, and
we therefore call it the sense of tact.
   All  parts of our body are not equally endowed  sensible and
                     J          x   j           insensible
with this sense ; some organs enjoy a most ex-  parts-
quisitely delicate sense of tact, while others may touch
foreign bodies, and even be cut and torn  by them, with-
out  the least sensation to the animal.  Now, the  most
sensible parts are most abundantly supplied with nerves,
and  where there are  no nerves there is no sensation.  If
an incision be made in  the  paw of a  living animal, and
the nerve of this part be exposed, it will   be found that
this  cord is  endowed with an extreme sensibility ; how-
ever slightly it is pinched or pricked, the animal displays
all the signs  of most acute  pain, and the  muscles, to
which  the nerve thus injured is distributed, are agitated
by convulsive contractions.
  From this it may be supposed, that to the oft£"neerves
nerves our organs owe their sensibility; and to "ion" sensa"
prove  this it is only necessary to  destroy one of these
cords.   For if the experiment be performed upon  the
limb of a  living animal, all  the parts supplied by the
nerve are immediately paralyzed, or deprived of the fac-
ulty  of sensation and motion.
  But  is this nerve,  whose action is indispensable to the 
168
ANATOMY AND PHYSIOLOGY.
exercise of these functions, itself charged with determin-
ing  the  motions, and  perceiving  the  sensations ?  Or
does it merely play the part of a conductor, and is it
destined only to transmit to the muscles the influence of
volition, and to convey  to another  organ, which may be
the seat of  the perception of sensations, the impressions
resulting from the contact of an external object  with  the
surface of the body ?
   To solve  this question physiologists have had recourse
to experiments upon living animals.
   If, in any point of its extent, the nerve going to  the
posterior claw of the frog, for example, be divided, and
the extremity thus separated from  the  rest of  the ner-
vous system, be  pinched or pricked, it is found to  be
completely insensible, while the part  situated above  the
section preserves all its sensibility;  the  parts of  the
limb, which receive branches from the inferior fragment
of the nerve, are likewise paralyzed.
   A nerve,  separated from the  system of which it made
a part, ceases then to discharge its  functions ; it cannot
consequently continue to be the seat of the perception of
sensation, and the conclusion must necessarily be drawn,
that it serves to transmit to the organ charged with this
function, the impressions received by  the parts endowed
with the sense of tact.
   This has been clearly demonstrated by all  the  re-
searches made relative  to this end.    The impression
produced by the contact of a body  with  the nerve itself,
or with the part in which the nerve is  ramified, cannot
be perceived, and cannot consequently produce a sensa-
tion, if it is not transmitted by the nerve to other organs.
   This fact once established,  we  are  naturally led  to 
FUNCTIONS OF RELATION.
169
ask, to what part  must the sensations be  conveyed  to
render the animal  conscious of them, or, in other words,
what is the organ  charged with perceiving them ?
   The nerves, the functions of  which we  have   Functions
                                              of the spinal
now been studying, all end in  the spinal  mar- marrow-
row, and the latter terminates  in  the brain ;  it is then
evident, that this faculty must reside in some  part of the
encephalon.   Let experiment decide for  us, whether it
is  in the spinal marrow, cerebellum, or cerebrum.
   When experiments are made upon the  spinal marrow,
similar to those already performed upon the nerves origi-
nating from it, the first observation is, that this organ is
extremely sensible : the slightest prick produces an acute
pain and convulsive motions ;  and if cut across, a com-
plete paralysis of  all  parts supplied by the nerves origi-
nating below the section is the  result, while those, whose
nerves arise from  that portion of the spinal marrow yet
in communication  with the brain,  continue  to enjoy the
faculty of sensation and motion.
   By care to maintain artificial respiration, so as to pre-
vent  the  animal  thus experimented on  from perishing
with asphyxia, in consequence of paralysis of the respira-
tory muscles,  it may be proved, that all parts  of the spi-
nal marrow and   medulla  oblongata lose the faculty of
determining voluntary movements, and of giving birth to
sensations, as soon as they are  separated from the brain,
and therefore  the  conclusion  must be drawn, that  the
faculty of perceiving sensations, or of determining volun-
tary movements, does not  reside in them.
   But with the brain it is  quite otherwise.   If bythe'brainln
           .1      i   •   i      r ,i •        • tne perception
we expose the two hemispheres of this organ in or sensations.
a living animal (a  pigeon for example), and irritate their
                   22 
170          ANATOMY AND PHYSIOLOGY.
surface with the point of a cutting instrument, we  shall
be struck with their insensibility ;  we may cut and tear
the substance of the brain, and the animal will not betray
the slightest sign of pain, not even appearing to be aware
of the mutilation going on ;  but if, as in the  experiment
of M. Flourens, this organ be removed, the animal falls
into a state of stupidity, from which it cannot be roused.
Its whole body becomes insensible, its senses no longer
act, and  if it moves, it is because impelled by some out-
ward power, and apparently the will is  not concerned in
the determination of any of its movements.
   From  this experiment it may be learned, that the ac-
tion  of the  brain is indispensable to the perception of
sensations and  manifestation of the will; and that the
impressions, received  by the nerves, must be conveyed
to this organ that the animal may  be conscious of them.
  .Review.    In the function of sensation there is  then a
very remarkable division of labor.   The parts, which by
their contact with foreign bodies are susceptible of giving
birth  to  sensations,  cannot  themselves  perceive  these
impressions; and on  the other hand, the organ, which
has for its exclusive function the perception of these im-
pressions, cannot itself directly receive them ; it is insen-
sible, and can be excited only by the  impressions trans-
mitted by the intervention of the nerves.
   Three properties then may be distinguished in  the
apparatus of the sense of tact; viz.:  1st, the  faculty of
receiving by contact with a foreign body such an impres-
sion, as  will give birth to a sensation ;  2nd, the  faculty
of transmitting these  impressions from the point of their
production to  the organ  charged with perceiving them ;
3d, that of giving to the animal the consciousness of their
existence, or of perception. 
FUNCTIONS OF RELATION.
171
   From the experiments of M. Flourens, and some other
physiologists,  it would appear, that in man and  animals
approaching him, such as the mammiferae and birds, this
latter faculty resides essentially in the hemispheres of the
brain.
   The  faculty of transmitting to this organ the   N«ves of
            J               o         o       sensation and
impressions produced by the contact of a foreign motion-
body belongs  to the nerves  of the cerebro-spinal system
and to the spinal marrow, though all nerves do not  pos-
sess this property.   All  those which originate from the
spinal marrow, possess at the same time both the power
of  transmitting to the muscles the influence of the will,
and of transmitting to the brain the  impressions alluded
to;  consequently,  they are  nerves  of motion   Functions
                J                             of the anterior
and sensation.  But the roots which fix them ra0n0dts po0ferZ
to the spinal marrow, do not present the same spmal nerves'
properties.  All these nerves, as  we have seen, originate
by two  orders of filaments, one  from  the  anterior, the
other from the posterior portion  of  the spinal marrow,
and the  interesting  experiments of M. Magendie have
shown,  that the latter serve  for the transmission  of  sen-
sations, and the former for the influence determining the
voluntary movements.
   If the posterior roots of a  spinal nerve are divided, this
cord is immediately deprived of the  faculty of transmit-
ting impressions ;  the part of the body  to which  it goes
becomes insensible, but the movements  remain under the
influence of the will:  while the  section of the anterior
roots, the posterior being  untouched, causes  the  loss  of
motion without destroying the sensation.
  By the division of the posterior roots of all the spinal
nerves,  the animal is not prevented from  executing vol- 
172
ANATOxMY AND PHYSIOLOGY.
untary motions, but its whole body,  (except the  head,
the nerves of which originate in the interior of the cra-
nium) is rendered completely insensible.   The posterior
roots are then  nerves  of sensation, and  the anterior  of
motion, and by their union the cord thus  resulting enjoys
at the same time the two faculties.
   m^S.0    Among the nerves from the cephalic  portion
of the encephalon, some possess the same  property with
the spinal; these are the facial or nerves of the fifth pair;
the pneumogastric  or  tenth  pair;  and the  suboccipital
or twelfth pair.   All these nerves originate by roots, one
of which presents a ganglionic enlargement and belongs
to sensation, and the  other has no  ganglion and belongs
to motion.
   The other cephalic nerves  are but  little or not  at all
sensible, and serve either for  motion, or for the transmis-
sion of certain peculiar impressions, produced by  light,
sounds, &c, and to which we shall have occasion  to re-
turn.
pottertoT coid   The different parts of the spinal marrow do not
umns  of the        .          i  -.       i   r   i    r
spinal marrow, possess in an equal degree the faculty of trans-
mitting sensations, or of exciting  motions;  sensation is
very  delicate on  the  posterior face of this organ, and
much more feeble on its anterior.
 thenecatne^e?~  Finally the ganglionary nervous system  is but
little, or not  at  all,  sensible :  these  ganglions  may be
pinched or  cut, as well  as the nerves proceeding from
them, without producing pain, or occasioning muscular
contractions.   It is also  worthy of remark, that, in the
state of health, the internal organs receiving these nerves
transmit to  us very feeble and  confused sensations, and
their sensibility is only  developed in certain diseases. 
FUNCTIONS OF RELATION.
173
In this case it is to be  presumed, that  the sensations ar-
rive at the brain only by the intervention of the branches,
which unite the nerves of the ganglionary system to each
of the spinal nerves.  But this point in physiology calls
for new investigations.
   Till now we have been occupied only by the special senses.
sensations produced  by the  contact  of a  material  body
upon  our  organs and with the  function which  permits us
to recognise the existence of objects, which resist our
movements, and  to  judge of the consistence, degree of
polish, temperature,  and, to a certain point, form of these
objects.   But these  are not the only sensations these ob-
jects  awaken in us,  and we  also enjoy  the faculty of ap-
preciating several of their  qualities, which  completely
escape the sense of touch, such as their  taste, odor, colors,
and the sounds they produce.
   These  faculties constitute the special senses of man
and most animals.   For  the perception of these sensa-
tions, as in the exercise of touch, the concurrence of the
brain must be obtained to judge of them, and of a nerve
to transmit to this organ the  sensation produced ; but the
division of labor is here carried yet farther, for this nerve
is not fitted itself to receive the impression: the  latter
must  be received by a special instrument and  transmitted
by the nerve of this organ to the brain.  Thus the light,
to produce upon us any sensation, must necessarily strike
upon  a determined  part  of  the  body,  the  sensibility of
which is modified, although the nerve which conducts to
the brain  the impression thus received, is itself insensible
to this agent.   The  nerves of the special senses all ori-
ginate from the brain, or the  neighboring part of  the me-
dulla  oblongata, and enjoy but in a  very limited degree 
174
ANATOMY AND PHYSIOLOGY.
the sense of touch.   The  optic nerve  may be  pinched
and cut without producing pain.  But the organs, which
are the seat of  these special senses, and are all lodged in
the head, receive branches from the trifacial nerve, which
give to them their sensation.
   These different modifications of the faculty of sensation
constitute the five senses, by means of which we acquire
all the ideas we have of surrounding objects.
   Let us now examine in a particular manner how  each
of these faculties is executed, and let us study the instru-
ments, which serve both for touch, taste, smell,  hearing,
and sight.

                  THE SENSE OF TOUCH.
   All animals enjoy a sense of touch more or less  deli-
cate, which is executed by means of the membrane cover-
ing the surface  of the body.   To  study it we must first
examine the structure of the skin.
 sttrheCtsUkTn.of   In man  tne exterior surface of the body and
the cavities in the interior which communicate externally,
such as the digestive canal, &c, are covered with a teg-
umentary membrane varying  in thickness, and very dif-
ferent from the substance of the parts covered ;  which is
continuous throughout, and  really forms but  one whole.
Its properties  however, are  not always  the same, and it
is  known by different names, as  it is folded inward  to
line the different cavities,  or  spread upon the  exterior
surface of the body.  The internal portion of this gene-
ral tegumentary membrane is called the mucous  mem-
brane, and the external the skin.
   The skin  is composed  of three  layers :  the dermis or
chorion, the rete mucosum (mucous net work),  and the
epidermis. 
                FUNCTIONS OF RELATION.            175

  The dermis forms the deepest and thickest layer  nermis.
of the skin.   It  is a white, supple membrane, but very
elastic and resistent.   It is composed of a great number
of fibres and lamellae  interlaced  in a very  serrated man-
ner.  Its internal face is united  to the neighboring parts
by a  layer, varying in thickness,  of cellular tissue,  and
at some points giving attachment to  the muscular fibres,
which serve  to  move it.   Lastly,  upon its surface are a
great number of small reddish prominences, very sensible,
and arranged in pairs,  forming  in certain parts of the
body, such as the palm of the hands  and  extremities of
the fingers, regular series.   These bodies are known as
the papillce of the  skin, and  the dermis of the skin of
certain  animals, when prepared by tanning, constitutes
leather.
   The rete mucosum is a plexus of vessels, soft J*,,,,
in  consistence,  covering the dermis, and  filled  with a
pulpy granulated material, to which  the skin owes its
color, and the tint  of which, of  course, varies in the dif-
ferent races, and  even in different individuals.  In ne-
groes this coloring matter  is black; in Europeans,  it is
white.  When the rete mucosum forming it  has been
destroyed, it is  not reproduced,  and  for this reason the
cicatrices in the skin are white, even in negroes.
  Finally, the epidermis is a kind of  semi-trans- Epidermis.
parent varnish, covering  the surface of  the skin, to which
it is moulded ;  it is not  a sensible part, nor even living,
but a matter secreted  by the skin, and  only takes a  cer-
tain degree of solidity when  dry.  Thus, in  those parts
of the body, which are withdrawn  from the action of the
air, it is soft and indistinct; and in animals living in the
water it is  not solidified,  except  when converted  into
stony matter, as in lobsters and most Crustacea. 
|76           ANATOMY AND PHYSIOLOGY.

  pores.     Upon the surface of the epidermis may be found
a multitude  of little openings,  called pores  of the skin.
They correspond  to  the summit of the  papillae  already
perspiration, mentioned, and open a passage to the perspiration,
which is an acid liquid  formed  by secretion,  and  not  to
be  confounded with  the  moisture continually exhaled
upon the surface of the  skin, and  which constitutes in-
sensible transpiration.   These pores are extremely small,
and do  not traverse the  dermis,  and must be  considered
as the secretory ducts of the  organs secreting the sweat.1
  Hair.     We also find upon  the surface other and larger
openings,  some of which  give  passage to  the hairs, the
mode of the formation of which we shall hereafter inves-
tigate ;  and  from others, there  distils a  fatty matter se-
creted by follicles lodged  in  the thickness of this mem-
  Naiis.   brane ; lastly, at some points of the  surface of the
body, we find issuing  from  the  substance of the  skin
horny plates called nails, in nature similar to  the hairs.
 sseeansa°tionhe   The sense of touch  resides in the  dermis, and
seems  to  belong  especially to  the papillae covering  its
surface.  All parts of the  skin  are not  equally sensible,
which depends not merely upon  the  number  of nerves
distributed to  them, but  also upon the  thickness of the
epidermis covering them.
   The  principal use,  then, of the epidermis is to oppose
the evaporation of the liquids contained in  the body, and
to protect the skin, properly  so called, from the immedi-
ate contact of foreign  bodies, so as to moderate the im-

  1  The perspiration is an acid liquid, as the urine and the gastric juice.
To be convinced of it apply upon the  skin, moistened by this secretion, a
piece of paper colored  blue by toumesol; its color will  be changed  to red,
as always results from  the action of an acid. 
FUNCTIONS OF RELATION.
177
pressions  produced by  this contact.   We have  already
seen, that this solid covering is  insensible, and  as  it is
always interposed between the dermis and external ob-
jects, by contact with which upon this membrane sensa-
tion is caused, it will  be easy to understand, that  the
thicker the epidermic layer, the more is the dermis with-
drawn from the action  of foreign bodies,  and the more
obtuse the impressions  it  must receive.   Now, in some
parts of the body, the heel for example, the epidermis is
very thick ; while in others, the extremity of  the fingers,
the  lips,  &c, it is extremely thin.   Wherever  too  the
skin is exposed  to friction, its epidermis is  thickened.
Every one knows that the layer formed in the hands of
blacksmiths and similar workmen becomes thick, hard,
and wrinkled.   Lastly, in some animals the epidermis is
encrusted with  calcareous matter, and becomes  entirely
inflexible ; in this case, the surface of the body is  ren-
dered  completely insensible.
   The sense of tact,  as it exists  in  all parts  of  Tta0cutc!nnd
the surface  of our bodies,  is  sufficient to make  us ac-
quainted  with the consistence,  temperature   and some
other properties of the  bodies in contact with it.  This
sense is then only exercised passively, and may therefore
be designated as tact;  but at other  times the part  pos-
sessed of  this sensibility is actively impressed  ; muscular
contractions directed  by the will multiply and vary the
points of contact with  an external  object, and then we
give to this sense the  name of touch.
   Touch  is then only tact perfected and made  active;
but it can be exercised  only by organs arranged so as to
be moulded in some sort upon the objects to be handled.
  In man, the hand is the special organ of touch, ofTiT
                  23 
178
ANATOMY AND PHYSIOLOGY.
and its structure is very favorable to the exercise of this
sense.   Its  epidermis  is thin, smooth, and very supple,
its chorion is abundantly supplied with papillae and nerves,
and reposes upon a thick layer of very elastic fatty cellu-
lar  tissue.   Finally, the mobility and flexibility of the
fingers are extreme, and the length of these organs is con-
siderable ;  now these circumstances  are the more advan-
tageous, in that  they tend  to increase the  sensibility of
the part, and permit  it to be applied  to all bodies, what-
ever be the irregularity of their figure.   But another or-
ganic disposition, which no  less contributes to the  per-
fection of our touch, is the power possessed  by man of
opposing the  thumb  to the other fingers, so as to be
able to  enclose small objects between  the parts of the
hand, which are precisely those in which the sensation is
the most exquisite.
  In most animals the organs of touch are arranged in a
manner much less favorable.   In  the mammiferae, for ex-
ample, this sense becomes  obtuse  as the  fingers become
inflexible, and are enveloped in nails, by which they are
armed.   Sometimes, however, the place of the hands is
supplied by other organs of no  less  perfect structure, as
the trunk  of the elephant;  and  finally,  some animals
employ the tongue as an instrument of touch, while others
are provided with particular  appendages, answering the
same purposes, and which are called tentacular, palpae, &c.
thi^sense.  Touch enables us to appreciate  more or less ex-
actly most of the physical properties of the  bodies, on
which it is  exercised ; their dimensions, form, tempera-
ture, consistence, polish, weight,  movements,  &c.   This
sense is so perfect, that several philosophers of antiquity,
as well as of modern times,  have  considered  it as more 
FUNCTIONS OF RELATION.
179
useful than sight or hearing, and as being even the source
of our intelligence.   These  opinions  are evidently  ex-
aggerated, for the touch has really no prerogative over the
other senses; and in some monkeys, whose intelligence
is incomparably less developed than that of man, the or-
gans of touch are as perfect as in the human  body.
SENSE OF TASTE.
   The sense of taste, like  that of touch, is excited  by
the contact of external objects upon  certain surfaces of
our  body ;  but  it acquaints us  with properties, which
escape the touch, to wit, the tastes of bodies.
   All substances do not act upon  the organ of  Ti?0Sdfe°f
taste.   Some are very sapid, others but  slightly so, and
many are completely insipid.   The cause of this difference
is unknown, but it is  found, that generally  those bodies
which cannot be dissolved in water, have no taste, while
most of the soluble are more or less sapid.  Their solu-
tion  appears even  to  be  a necessary condition of their
action upon the organ of taste; for when  this organ is
completely dry, the sensation of taste is no longer impart-
ed ;  and there are  substances, which, being insoluble in
water, are insipid in their ordinary state, but which acquire
a strong taste when dissolved in some other liquid, such
as spirits of wine.
   The knowledge of the taste of bodies  serves  Be^mtba
principally to direct animals in  the  choice  of their  food :
and  therefore the organ of taste is  placed always  at  the
entrance of the  digestive tube.  The tongue is the prin-
cipal seat  of it, but the other parts of the mouth may also
experience the sensation of certain tastes.
  The mucous membrane  covering the tongue  IK"^0/ 
IgQ           ANATOMY AND PHYSIOLOGY.

is abundantly supplied with blood  vessels, and  presents
on its superior surface many eminences of various forms,
which render it rough.  These eminences, or papillae, are
of various  kinds;  some lenticular,  and few  in  number,
consist of a collection of mucous follicles; others, fungi-
form or conical and very numerous, are vascular or  ner-
vous ; the last cover the terminations of the lingual nerve,
and appear principally to serve for the  sense of taste.
 Netongue.lhe  The tongue, the substance  of which is formed
by many muscles interlaced, receives the branches of sev-
eral nerves ; some serving  to excite motion, others to  con-
duct to the brain the sensation of the tastes.  The trifacial
nerve or the nerve  of the  fifth pair, which  springs  from
the superior extremity of the spinal marrow, and separates
from the encephalon near  the anterior border of the annu-
lar protuberance,  (see fig. 29) supplies these latter func-
tions.  It issues from the  cranium behind  the orbit, and
divides into three principal branches, to wit; the opthal-
mic  nerve supplying the  apparatus of  vision,  etc., the
superior maxillary  nerve, which is  distributed to  the
upper jaw and cheek, and the inferior maxillary  nerve,
one of the principal branches of which bears the name of
the lingual nerve, and terminates in the mucous  mem-
brane of the tongue.
   If the lingual nerve be  divided in a living animal, the
motions of the tongue are not paralyzed, but the organ is
rendered insensible to tastes; and if the trunk of the  trifa-
cial nerve be divided in the interior of the cranium the
sense of taste is destroyed, not merely in the tongue, but
in all the other parts of the mouth.
   The section of  the nerves  of  the ninth and  eleventh
pair, which also go to the tongue,  does  not deprive the 
FUNCTIONS OF RELATION.
181
animal of the faculty of perceiving tastes, but occasions
the loss of motion in the tongue  and the other parts, to
which these nerves are distributed.
   It follows then that the lingual  branch of the fifth pair
is  the special nerve of taste.

                    SENSE OF SMELL.
   Certain bodies possess the peculiarity of exciting in us
sensations  of a  particular  nature, which cannot be  per-
ceived by  the aid of the  sense  of touch  or taste, and
which depend upon the odor they exhale.
   Odors are produced by particles of an extreme   odors.
tenuity, which escape  from odoriferous bodies, and  are
diffused  in the  atmosphere, as  vapors.  All volatile or
gaseous bodies are not odoriferous; but, in general, those
which may be easily transformed  into vapor,  diffuse  little
or no odor, and  in most cases we find, that  odoriferous
substances become more so when  the  circumstances in
which they are placed favor volatilization.   But yet  the
quantity  of matter thus diffused in  the  air, to produce
even the strongest odors, is extremely small.  A particle
of musk, for example, may perfume the air of an apart-
ment for a long time,  without any  sensible change of
weight.   A multitude of bodies,  such as water, clothing,
etc., may imbibe these vapors, and in their turn become
odoriferous; but  other  substances, such  as  glass, com-
pletely oppose their passage.  We may perceive the odor
of bodies at a great distance from us; but  to  arouse  our
olfactory sense,  odoriferous  particles, emanating from
these bodies, must arrive in contact with the  organ  des-
tined to  receive  them.   And in  this the  mechanism of 
 182           ANATOMY AND PHYSIOLOGY.

 smell is analogous  to  the  taste  and touch, while with
 sight and hearing, as we shall soon see, it is quite other-
 wise.
  appaS.    The air is called the vehicle of odors; by this
 fluid  they are transported to a distance, so as to reach us.
 It is then plain, that the organ destined to perceive  them
 must always be placed  so as to receive their contact, and
 experience teaches us,  that to have  this  organ  discharge
 its functions, the membrane  touched by the odors  must
 be continually moistened and covered by  a  liquid proper
 to absorb the odoriferous particles, and to fix them  for a
 certain  time upon  its  olfactory surface.   If this  surface
 were exterior, the  former of these  conditions  would  be
 fulfilled, but not the latter;  the odors would strike it, but
 it would soon dry up, and become insensible to their con-
 tact.  Smell must consequently reside in the walls of a
 cavity within the body,  communicating freely externally;
 and the more rapidly and regularly the air,  conveying to
 us the odors, is renewed, the more favorable are the con-
 ditions to the exercise of this sense.
  This  actually takes place, not merely in man, but also
 in all the other  mammiferae ; in  birds and reptiles also
 the sense of smell  has  its  seat in the nasal fossae, and
 these cavities are  constantly traversed by the  air, going
 to the lungs to supply the requisitions of  the respiration.
 They communicate  outwardly by the nostrils, and open
 posteriorly into the pharynx, at a short distance from the
 glottis.  (See fig.  23.)    Thus whenever the  mouth is
shut,  the air must pass  through them  to  reach the latter
opening, and they may be considered  as  the  anterior
portion of the aerial tube. 
FUNCTIONS OF RELATION.
183
d -t
   The nasal fossae are sepa-
 rated from  each  other by a
 vertical  partition,  directed
 from  before backward,  and
 occupying  the  median  line
 of the face ;  their walls are
 formed  by  various  bones of
 the face,  and  by the carti-
 lages of the nose, and  their
 extent is very considerable.   Upon  the external  surface
 may be  remarked  three  projecting  plates  curved  upon
 themselves, and called the ossa turbinata (g, i, k,).  They
 increase the surface of this wall, and are separated  from
 one  another by a  longitudinal  furrow, called a  meatus
 (f h,).   Lastly, these fossae  communicate with  sinuses
 hollowed  out in the os frontis,2 ossa maxillaria superiora,
 etc.   The mucous  membrane, lining the  nasal fossae, is
 called the pituitary membrane; it is thick, and prolonged
 beyond the borders of  the ossa  turbinata, so that the air
 can  traverse the olfactory  cavities  only by narrow and
 long  routes, and the least  swelling of this membrane
 renders the passage of  this fluid difficult,  or even impos-
 sible.  The surface of the  pituitary membrane presents
 many little projections, which give  it  a velvety aspect;

   1 This vertical section of  the nasal fossfe represents the exterior wall of
 one of these cavities; — a,  mouth, — b, nostril, — c, posterior opening of
 the nasal fossae, — d, portion of the base of the cranium, —e, forehead,—
/, inferior meatus, — g, inferior turbinated bone, — h, median meatus,—i,
 median turbinated bone, — £, superior turbinated, — /,  frontal sinus, — m,
 spheroidal sinus, —n, outlet of the eustachian tube.
  2 The frontal sinuses do not exist in infancy, but are developed  by age
 and acquire very considerable dimension;  these cavities cause the  projec-
 tion of the inferior part of the forehead above the root of the nose. 
184
ANATOMY AND PHYSIOLOGY.
lastly it is continually lubricated by a liquid more or less
viscous, called the  nasal  mucus,  which  appears to be
formed in a great measure in  the  sinuses already  men-
tioned, and it  receives a  very great number of  nervous
filaments, some from the fifth  pair, and others from the
olfactory or first pair.
o/the'smeli!  The mechanism of smell is very simple ;  it is
only necessary, that the nasal mucus should imbibe the
odoriferous  particles, diffused  in the air  traversing the
nasal fossae, and that these particles should be thus ar-
rested upon that part of the  pituitary membrane which
receives the filaments of the olfactory nerve.   From this
it can  easily be conceived, how important is the  nasal
mucus to  the sense of smell, and how the changes in the
nature of this liquid, which take place during coryza or
cold in the head, may cause, for a time, the loss of this
sense.
   In the superior part of the nasal fossae the branches of
the olfactory nerve  are most numerous, the nasal mucus
most abundant, and the routes followed by the air  most
contracted.   In this part, therefore,  are the odors  most
easily and vividly perceived.  It would even appear, that
the principal use of the nose is to direct  the inspired air
to the vault of  the nasal fossae ; persons losing this organ
at the same time lose the  sense of smell, and cases  have
occurred,  where it  was  sufficient, to adjust an artificial
nose upon the face  of the  patient, in  order to restore this
sense.
 Nsmeen.of  The olfactory nerve has generally been  consid-
ered as the nerve destined to convey to the brain  the im-
pressions produced  by odors ; but the nerve from the fifth
pair appears to be of important service in the discharge 
FUNCTIONS OF RELATION.
185
of this function, for M.  Magendie has proved  that  its
section rendered the pituitary membrane insensible to the
strongest odors.
   With regard to the uses of the sinuses which  Usejnu0SeS,he
communicate with the nasal  fossae by narrow openings,
and  which are lined by a  thin membrane, nothing positive
is known.  It has been remarked, however, that animals,
in whom  these  cavities are  more vast,  are also  those in
whom the sense of  smell is the most delicate.

                    SENSE  OF  HEARING.
   Hearing is the function which makes  us acquainted
with the sounds produced by vibrating bodies.
   The apparatus of hearing is very complicated ; apparatus.
the different parts of which it is composed  are for the
most part extremely small;  thus it occupies but a very
small space, and is almost entirely contained in the inte-
rior of  a bony prominence, which from either side of the
head, advances into the interior of the cranium, and con-
stitutes that part of the  temporal bone called, from  its
hardness, the petrous portion. (Fig. 32, e.)
   It may be divided into  three portions, namely, the ex-
ternal, middle, and internal ear.
   The  external  ear  is composed  of the pavilion External ear.
of the ear, and auditory canal.
   The  pavilion of the ear (a) is  a fibro-cartila-  ^J1"",.0'
ginous plate, supple and  elastic, which  is perfectly free
in the greater part of its extent, and which adheres  to
the edge of the  auditory  canal.   The skin covering it is
thin,  dry,  and  very tense ;  its surface  turns in several
ways, and presents various  eminences and  depressions,
the most  considerable of which  is the  concha (d).   It
                   24 
]gg             ANATOMY AND PHYSIOLOGY.

                            Fig.   32.'
                k       h  g  e'"e'"/   e'     b

  Aduct°.ry forms a sort of tunnel very open,  and continuous
with the auditory duct, which  is  buried in  the  temporal


  1  This figure represents a vertical section of  the auditory apparatus with
the  interior parts slightly magnified, that they  may be better seen,  a, Pa-
vilion of the ear, — b, lobule of the pavilion, — c, small eminence called the
antitragus, — d, concha,  the bottom of which is continuous with the audi-
tory duct, — e, e, portion of the temporal bone, called the petrous, in which
is lodged  the auditory  apparatus, — e', mastoid  portion of the tempo-
ral  bone, — e",  portion  of the glenroid fossa  in which  the lower jaw  is
articulated, — e'", styloid process of the temporal  serving for the insertion
of the muscles and ligaments of the os hyoides, — e"", extremity of the
canal traversed  by the internal carotid artery before entering the cavity of
the cranium,—/, auditory duct, — g,  tympanu n, — h, cavity from which
has been taken the chain of bones, — i, openii gs from the cavity of the
tympanum  into  the cells {j) of the  petrous portion,— on the internal  wall
of the  cavity we find two  openings, fenestra oialis, and rotunda, —k, the
eustachian  tube conducting from the  cavity to  the summit of the pharynx,
— I, vestibule, — m, semicircular canals, — n, cochlea,- o, acoustic nerve. 
FUNCTIONS OF RELATION.
187
bone, and curves upward and forward.   The skin lining
this duct  terminates abruptly at its  internal extremity,
and beneath  it, we  find many small  sebaceous  follicles,
which furnish the yellow and bitter matter known as the
cerumen.
   The  middle ear is composed  of the cavity of  kiddie ear.
the  tympanum  and the parts dependent upon  it.
                                The cavity  (fig. 32,   cavity.
                             h),  is of an irregular  form,
                             hollowed in the petrous  sub-
                             stance of the temporal  bone,
                           e  and making part of the  audi-
                             tory  duct,  from  which  it  is
                             separated by a  membranous
                          f partition, very tense and elas-
              j \  \          tic, called the tympanum (b).
    a        b  c  b         Opposite  the   opening,   in
which the tympanum is, as it  were, set,  (that is, upon the
internal portion  of the  cavity), may be  found two  other
holes, which  are covered in  the  same  manner by a  tense
membrane ; they are called from their form, the oval and
the round fenestra.  Upon the posterior wall of the cavity

  1 This figure represents the external wall of the  cavity, the tympanum,
the bones of the ear, and their muscles, all enlarged, a, a, Frame of the
tympanum, — b, tympanum, — c, handle of the mallet, its end resting upon
the middle of the tympanum, — d, head of the mallet articulating with the
anvil, — e, process, which springs from below the neck of the mallet, and
buries itself in the glenoidal fissure of the temporal bone; its extremity
gives attachment to the anterior muscle of the mallet,—/, internal muscle
of the mallet, — g, anvil, a vertical branch of which  rests upon the walls
of the cavity, and a vertical branch articulates with the os orbiculare (/*), —
i, stirrup, the summit of which articulates with the  os orbiculare, and the
base of which rests upon the membrane of the fenestra ovalis; — k, muscle
of the stirrup. 
188
ANATOMY AND PHYSIOLOGY.
is a hole conducting to the cells of  the  mastoid  portion
of the temporal bone, and on its inferior wall may be seen
the opening of the  eustachian tube, a long and  narrow
duct, with  an  outlet to the  posterior  part of the nasal
fossae, and  which thus establishes  a communication be-
tween the cavity of the tympanum and the  external air.
Finally, this cavity is traversed by a chain of little bones,
which extends from  the tympanum to  the  membrane of
the fenestra ovalis, and which leans, by means of a branch
directed to the side,  upon  the posterior wall of the cavity.
(Fig. 33.)
    Fio-. 34.1       These bones are four in number, and
      a   b      are called  the mallet, or malleus (fig.
                34, a), the anvil, or incus  (b),  os lenti-
                culare (c),  and stirrup, or stapes (d).
                A small stalk, which may be compared
                to the handle, and which belongs to the
                malleus, rests against the tympanum, and
                the base of the stapes thus reposes upon
                the membrane of  the  fenestra  ovalis.
Finally  little muscles fixed to these  bones, impress upon
them  movements, by means of which they press more  or
less strongly upon these  membranes, and  consequently
augment or diminish  their  degree of tension.
 rmemai ear.   The internal ear, as well as the middle, is en-
tirely  contained within  the petrous  portion.   It is com-
posed of several  cavities, which communicate  together,
and which are called the vestibule, semicircular  canals,
and the cochlea.   The  vestibule  occupies the  middle

  1 Bones  of the ear separated, — a, malleus or mallet, — b, incus or anvil,
— c, os orbiculare,  — d, stapes or stirrup.
-H 
FUNCTIONS OF RELATION.
189
part, and communicates with the cavity by the  fenestra
ovalis.   The semicircular canals project  upon the  supe-
rior and posterior part of  the vestibule; they are three
in number, and have the form of rounded  canals swelled
at one extremity, like  a  flask.   Lastly, the cochlea is  a
very singular organ, spirally twisted like the shell of the
animal whence it  takes  its name.   Its cavity is  divided
into two parts by  a longitudinal partition, semi-osseous,
semi-membranous; it  communicates with  the interior of
the vestibule, and  is separated from the cavity only by the
membrane of the fenestra rotunda.   This latter cavity is
filled with air;  the internal ear, on the contrary,  is filled
with an aqueous liquid, and the membrane lining the ves-
tibule, as well as  the  semicircular canals,  is not applied
to the  bony walls of the cavity, but is in  a manner sus-
pended in  their interior.
   The nerve of the eighth pair, which arises  Ance°ruvset.ic
from the medulla oblongata near the restiform body, and
which  departs from the encephalon between the pedun-
cle of the cerebellum and the annular protuberance, enters
the petrous portion through a bony passage called the in-
ternal  auditory canal,  and  terminates in the interior of
the membranous sacs of the vestibule, and semicircular
canals, and also in the cochlea.   Upon it  depends  the
sensibility  of the  organ of hearing,  and  therefore  it is
called the acoustic nerve.
   Such are the  principal parts of the auditory oS™"1
apparatus.   Let us now see the part taken  by each in the
exercise of the  sense of hearing.
   Hearing, we have said, is to make  us  acquainted with
sounds.
   Sound results from a very rapid vibratory mo-  NSoUUndof 
190
ANATOMY AND PHYSIOLOGY.
 tion of the particles of sonorous bodies.  To be  assured
 of this, it will suffice, merely to sprinkle some fine sand
 upon a plate of glass, or the table of a violin, and to pro-
 duce on this  plate or instrument any  sound  whatever.
 The grains of sand are at once agitated, and thrown into
 the air with a force proportioned  to the intensity of the
 sound.   The  undulations experienced by  the sonorous
 body are communicated to the air in contact with its sur-
 face, as they were communicated to the grains of sand in
 the preceding experiment;  and thus from  step  to  step
 are sounds propagated to a distance.  To perceive  these
 sounds,  the vibrations now  spoken of, must reach  the
 internal ear, and by their influence the liquid, which im-
 mediately bathes  the acoustic nerve, will itself be thrown
 into undulation.   To point out the  rationale of the mecha-
 nism of hearing, we must then follow the course of  these
 undulatory motions through the various parts of the audi-
 tory apparatus, interposed between the external air and
 the acoustic nerve.
 use of the   The sonorous vibrations of the air first strike
 pavilion of
 the ear.   tne pavilion of the ear.   In animals, where this
 part has the form of a horn, it serves to reflect the vibra-
 tions, and to augment the  intensity of the  sounds at its
 contracted extremity, as experiment easily proves.  Every
 body knows that  persons  a  little  deaf hear with much
 more facility when they use a similar horn, and if a thin
 membrane be stretched over  the open summit of a paper
 cone, and  its  surface  be  sprinkled with  fine sand, the
 movements of the sand will be found much more intense,
 when the sound arrives  at  the membrane  by the broad
outlet of the tunnel, than when coming from the opposite
 side. 
FUNCTIONS OF RELATION.
191
   In  man, the concha and the  auditory duct discharge
the same functions ; but the other parts of the pavilion
are not so arranged as to reflect sounds to the tympanum,
and they also appear to have other uses.   When sonorous
vibrations fall perpendicularly upon an elastic surface, the
undulatory motions, excited in the latter, are much more
intense than when the sound arrives obliquely; and it may
be concluded, that the varied directions of the surface of the
pavilion of the ear, are destined to present to the sonorous
waves, whatever  be  the direction in which they strike us,
a plane thus  arranged, and,  consequently,  they serve to
augment the  vibratory action of this  elastic appendage.
The pavilion  of the ear is not,  however, of very great
utility, and the loss of it does not much affect the hear-
ing.
   The vibrations, thus excited in the pavilion of au^toryofduct!
the ear, are communicated to the walls of the auditory
duct,  and thence  to the deeper seated  parts of the appa-
ratus  of hearing;  but  these movements can only be very
weak, and principally by the intervention of the air con-
tained in this duct the sounds penetrate  into the interior
of the ear.   Thus, if  the tube be plugged with cotton or
any other soft body,  which opposes  their passage,  the
perception of them is rendered indistinct.
   The tympanum serves principally to facilitate  Vympanum6
the transmission of sonorous vibrations from the external
air to the acoustic nerve.   The experiments  of one of
our most skilful physicians, M. Savart, prove that sounds,
by striking upon  a thin and moderately tense membrane,
excite in  it,  very easily, vibrations.   If a leaf of paper
be stretched upon a frame, and its surface powdered with
sand,  the latter is readily agitated, and collected so as to 
192
ANATOMY AND PHYSIOLOGY.
form varied lines, as soon as a sonorous body in vibration
is brought near.   If the  same experiment be made with
a plane of wood, or a leaf of paper, no  such movement
will result,  unless  the sound  employed  be extremely
intense.   But if to these latter bodies there be adapted
a membranous disc,  similar to the tympanum, they will
readily vibrate under the influence of sounds, which  be-
fore would have produced no appreciable effect.
   It is plain,  then, that the  tympanum must readily vi-
brate,  when sounds strike upon it, and that  its presence
must augment the facility  with which the other parts of
the auditory apparatus experience similar motions.
sionlf^oMds   The vibrations are transmitted from the mem-
vity"8   a brane of the tympanum to the bones of the ear,
to the  walls of the cavity, and especially to the air, with
which  this cavity is filled :  they thus arrive at the poste-
rior wall  of  the  cavity,  where  there  are  membranes
stretched  upon openings conducting  to the internal ear,
nearly as  the  tympanum is stretched between the audi-
tory duct  and the cavity.  These membranes must act in
the same  manner as  the latter, that is, easily be made to
vibrate, and transmit these  motions  to  the neighboring
parts.
 internal ear.   The posterior face  of these membranous discs
is in contact with the aqueous liquid, which  fills  the  in-
ternal  ear, and in this liquid are suspended the membra-
nous sacs,1 which, in their turn, are distended by another
liquid,  into which are plunged the terminal  filaments of

  1 They are called the membrane of the vestibule, and the tubes of the
semicircular  canals, according  as they occupy the vestibule or the semicir-
cular canals; in the cochlea there is nothing similar, and the liquid by which
it is filled, is the same which bathes the membrane of the vestibule. 
FUNCTIONS OF RELATION.
193
the acoustic nerve.  The vibrations executed  by these
membranes must then be transmitted to this liquid, after-
wards  be communicated to the membranous sac of  the
vestibule, and finally arrive at the nerve,  upon which their
action  produces the sensation of sound.
   From  the preceding observations, it  will be  uses of the
            •T       o                        air  contained
seen, that the air contained  in  the  cavity plays in the cavuv-
a very  important part in the mechanism of hearing ; now,
if this  cavity did  not  communicate externally, this air
would  soon be absorbed and disappear, and the vibrations
of the  tympanum could  be transmitted to the internal
ear,  only by the osseous walls  of  the  cavity,  and then
with difficulty.   This accounts  for the  use of the eusta-
chian tube, and explains to  us  in what way the obstruc-
tion  of this duct may become a cause of deafness.
   The tympanum is not indispensable to hearing, ^"'cavity.
for when this membrane is torn, the vibrations of the air
contained in the auditory duct are communicated without
interruption to the  air of the cavity, and thus arrive at
the  membranes  of the fenestra ovalis  and rotunda.  It
might  then be asked, what  is the  use of this,  and what
disadvantage could  arise, if, the cavity not existing, the
membranes of the fenestra ovalis and rotunda were placed
externally ?  To reply to this question  it must be borne
in mind  that the manner in  which the membranes vibrate
under  the influence of the same sound, varies with their
degree of dryness or  humidity, their temperature,  etc.
Now it is probable, that  two sounds make  upon us the
same  impression  whenever  they  cause  the  liquid,  in
which  the acoustic  nerve terminates,  to vibrate in the
same manner ;  and, consequently, in order that the same
sound  may always act upon us in  an identical manner,
                   25 
194           ANATOMY AND PHYSIOLOGY.
the membranes, which communicate directly their vibra-
tions to this liquid, must  constantly be at the same  tem-
perature, and the same degree of dryness ; and this is
precisely the case with the  membranes of the fenestra?
of the internal ear.   The air of the cavity being renewed
but very  gradually  is always completely charged  with
moisture, and at the same temperature, while if the cavity
did not exist, or had free external communication, the
condition of these membranes would be changed at every
instant, according as they were exposed  to the action of
air, hot or cold, dry or moist.
 E,1uabe!ian   This also explains  to us, why the eustachian
duct is long and narrow in all warm-blooded  animals,
while in the cold-blooded, such as the lizards,  it is  short
and very large.  In the former, the air must have  time to
ascend to the temperature of the body before penetrating
the cavity, while in the latter this temperature  being the
same with the atmosphere, the speedy renewal of the air
contained in the  cavity has no bad results.
  uses of the  We learn, therefore, that the  chain of bones
 bones of the
 ear-      traversing the cavity, and which rests  upon the
tympanum and the membrane of the fenestra ovalis, may
execute certain movements, by means of which the pres-
sure it exercises upon these membranes may be increased
or diminished.  The utility of this arrangement is easily
understood; if sand be sprinkled upon a membrane made
tense by a frame, and a sonorous body in  vibration be
approximated to it, it will be  found, that without in the
least  changing the  intensity of the sound, the violence
with which the sand  is thrown into the air will be increased
or diminished, as the tension of the membrane is increased
or diminished.   In the former case, it will execute under 
FUNCTIONS OF RELATION.
195
the influence of a sound of the same intensity vibratory
movements much more extensive, than when the tension
is increased.   From this we may infer, that the pressure
more or less strong of the malleus  upon the tympanum,
and of the stapes upon the  membrane of the  fenestra
ovalis, will prevent these membranes  from vibrating too
strongly under the influence of very intense sounds, with-
out depriving  them of  the faculty of vibrating,  when  a
feeble sound strikes them.   The pressure exercised upon
the membrane of the fenestra ovalis is thus  communicated
to the membrane of the fenestra  rotunda, by  the inter-
vention of the liquid with which the internal ear is filled ;
and the result is, that the bones of the organ of  hearing,
by  leaning upon the two membranes to which they are
fixed, prevent  the  sonorous  vibrations arriving at  the
acoustic  nerve, from being  so intense  as  to  injure  this
delicate organ.
  The loss of the malleus, incus, or os orbiculare dimin-
ishes the hearing, but  does  not  destroy it; that of the
stapes is, on  the contrary, followed  by deafness, for  this
bone, adhering to the membrane of the fenestra ovalis, by
its fall tears the  partition, and thus, the liquid  contained
in the vestibulum being lost, the  acoustic  nerve can no
longer discharge its functions.
  We see then, that all the parts composing the Modifications
                                    10     of the auditory
external  and  middle  ear serve to perfect the aPParalus-
hearing, without, however, being absolutely necessary to
the exercise of this sense.  Thus they gradually disap-
pear, as we depart from man, and study the structure of
the ear in animals gradually descending in the scale of
beings.   In birds there is no pavilion of the ear; in  rep-
tiles the external auditory duct is also wanting, the tym- 
196
ANATOMY AND PHYSIOLOGY.
panum becomes external and the structure of the cavity
is simplified;   finally,  in  most  fishes  there  is  neither
concha, external,  nor middle ear.
   In animals placed yet lower in the series of  beings, it
is the same with the cochlea, and the semicircular canals,
parts, the uses of which are not well  known;1 but  the
membranous vestibule is an organ never wanting; wher-
ever there exists an  auditory apparatus, there is always
found a small membranous sac filled with liquid, in which
the acoustic nerve terminates, and this vestibule is always
an instrument indispensable to the exercise of the sense
of hearing.
SIGHT.
   Sight is that faculty, which makes  us  sensible  of the
action of light, and  which acquaints  us through this
agent, with the form  of  bodies,  their  color, size and
position.
  Apparatus of    Tne  apparatus           pig 35 2
charged with  this function     ch s1    s   cr       b
is composed of the nerve  of       '\. Nw L^
the second  pair, of the eye,   r     ft^slS^ks.   **
and the several parts  destin-       '2Mm9S^Kmk\
ed for the protection  or mo-   n-•^B^|M[   |I|\^]I'
tion of this organ.                ••^l*3BHBys,sv
  ?he0beeye0.f  The globe of the eye,   *'"    ^^g^^
with which  we shall  first be           «' r    vpcb
occupied, is a hollow  sphere, a little swollen in front, and

  1 From the experiments of M. Flourens it would appear, that the destruc-
tion of the semicircular canals does not destroy hearing, but renders it con-
fused and painful.
  * Interior of the eye, — c, transparent cornea, — s, sclerotica, — s\ portion
of the sclerotica, turned outward to display the membranes situated beneath, 
FUNCTIONS OF RELATION.
197
filled with humors more or less fluid.  Its exterior  en-
velope is composed of two very distinct parts, one white,
opaque,  and fibrous, called  the sclerotica (s); the other
transparent and similar to a plate of horn, therefore called
the cornea (c).   The latter occupies the front of the eye,
and is, as it were, set in a circular opening of the sclero-
tica.   Its external surface is more rounded than  that of
the latter membrane, and it resembles a watch-glass ap-
plied upon a sphere, and  projecting beyond its surface.
   At a short distance behind  the cornea,  in the  ws.
interior of the eye, is a membranous partition (i), which
is stretched  transversely, and fixed to the anterior border
of the sclerotica, quite around  the cornea.  This kind of
diaphragm, which varies in color with .the individual, is
called the iris, and presents in its middle a circular open-
ing named  the  pupil (p).   Muscular fibres  may be  de-
tected in the tissue of this organ, directed  like rays from
the edge of the pupil towards the circumference  of the
iris, and other fibres of the same nature, which are circu-
lar and surround this opening like  a ring.   When  the
former  contract, the  pupil  dilates, by the  action of the
latter, it  is contracted.
   The space comprised between the cornea and  cAhSr'
the iris constitutes the anterior chamber of the eye (ca).
By the opening  of the pupil  it communicates with the
posterior  chamber, a cavity situated  behind the  iris, and
which is  filled,  as well as the former  chamber,  by  the
— ch, choroid, — r, retina, — n, optic nerve, ca, anterior chamber of the eye
placed between the cornea and iris, and filled with the aqueous  humor, —
i, iris, —p, pupil, — cr, crystalline lens placed behind the pupil, —pc, ciliary
processes,—v, vitreous humor,—b,b, portion of the conjunctiva which,
after having covered the anterior part of the eye, is detached from it to line
the eyelids. 
198
ANATOMY AND PHYSIOLOGY.
aqueous humor, a  perfectly transparent liquid composed
of water, holding in solution a little albumen and a small
quantity of salts, such as  are met with in  all the secre-
tions of the animal economy.   This humor  is supposed
to be formed by a membrane behind the iris, which  pre-
processes,  sents a great number of radiated folds, called cil-
iary processes (pc).
crystalline.  Almost directly  behind  the pupil is a transpa-
rent lens, called the crystalline (cr).   It is lodged  in a
diaphanous  membranous sac (the capsule of the crystal-
line lens), and appears to  be the product of a secretion
from it; for when taken from the eye of the living ani-
mal without destroying its capsule, a new  lens  is found
to take  the place of the old.  It is  also remarked,  that
this body is composed of a great number of concentric
layers, constantly increasing in hardness from the circum-
ference  to  the  centre, which agrees  with our remarks
upon the  mode of its formation.  Its  posterior face  is
also much more convex than its anterior.
  \umOT."   Behind the crystalline lens we find a large ge-
latinous diaphanous mass, resembling the white of an  egg,
and enveloped in a membrane of extreme tenuity, a great
number of lammelke from which  extend inward, so as to
form partitions  or cells.   This membrane is called the
hyaloid, and the humor found in it the vitreous humor (v).
  Retina.    Every where, except in front, where are the
crystalline  lens and the iris, the vitreous  humor  is  sur-
rounded by a soft white membrane called  the retina (r),
which is only separated from the  sclerotica by another
  choroid, membrane, equally thin, which is called the choroid
(ch).   The latter is principally formed by a net-work of
blood vessels, and is stained with a black matter, which 
                FUNCTIONS OF RELATION.            ]99

 gives to the bottom of the eye  that deep color, which is
 seen through  the  pupil, and which is  wanting in those
 persons and animals called albinos.
   The globe  of the eye receives several nerves, optic nerve.
 The most remarkable for its size and functions is the op-
 tic nerve (n), which traverses  the posterior  part of the
 sclerotica, and is continuous with the  retina, which ap-
 pears in fact but an expansion of it.   The other nerves
 of  the globe of the eye  are extremely  small, and ™%l
 are  called the ciliary nerves :  they spring  from a small
 ganglion, formed by the union  of some branches of the
 nerves of the third  and  fifth pairs (see fig. 29), and are
 distributed to the  iris and the proximate  parts of the in-
 terior  of the globe of the eye.
   By  the intervention  of light, we  have said, Mecvhjsjonm of
 bodies placed around us act upon our sight.  Those which
 emit light, the sun and  bodies  in  ignition, for example,
 are  visible of themselves;  but others  become so,  only
 when  the light striking upon them is reflected in such a
 way as to meet our eyes.
   This agent moves with  an extreme rapidity; it  can
 act upon our senses only to the extent  it strikes upon the
 retina, situated at the bottom of the eye.  Opaque bodies
 reflect or absorb it, but transparent  bodies,  such as the
 atmosphere and water, afford it a free passage.
   The first condition, then, for the exercise  of vision  is
 the absence of every opaque body between  external ob-
jects and the  bottom of  the eye.   Therefore the cornea,
 which  covers  the anterior part of this organ, like a watch
 glass,  is  completely transparent,  and  the light, which
 traverses it, and passes  through the opening of the pupil,
 readily arrives at  the retina; for it only encounters on 
200
ANATOMY AND PHYSIOLOGY.
the way  the  crystalline lens, which is diaphanous, and
the humors, which are equally so.
   But in  some diseases it is quite different, and this loss
of transparency always causes blindness.   In the  affec-
tion known as the cataract, for instance, the crystalline
lens becomes opaque, and  thus  opposes  the  passage  of
light:  and when white spots or pellicles are formed upon
the cornea, this membrane  becomes a kind  of screen,
which prevents the luminous rays from penetrating to the
eye, and thus entirely destroys vision.
   The diaphanous parts of  the  globe of the  eye do not
serve  to give passage to the  light merely.   Their princi-
pal use is to change the direction of  the rays which enter
this organ, so  as to collect them  upon some point of the
retina.  The  interior of the eye  resembles exactly the
optical instrument known as the camera obscura, and the
image of  the objects seen by us  is painted  upon the re-
tina, as upon the curtain placed  behind  the latter.  To
understand this phenomenon, it is necessary to examine
the course of  luminous  rays through transparent bodies
in general, and to  apply the knowledge thus acquired,  to
the study  of the mechanism of vision.
   Light  ordinarily advances in  a straight line,  and the
different rays, which start from any one  point,  are dis-
persed according to the  direction in which they travel,
and the distance  of the space traversed.  When  these
rays fall perpendicularly upon the surface of a  transpa-
rent body, they traverse  it \yithout any change in direc-
tion ;  but if they strike it obliquely,  there is always more
or less deviation from their primitive course.  If the body,
into which they  penetrate, be more dense  than that from
which  they issue, if they pass  from air  into water   or 
FUNCTIONS OF RELATION.
201
glass, for example, they then form an elbow and approach
the perpendicular at  the  point of immersion.   If, on the
contrary, they pass from  a dense to a rare medium, they
depart from this perpendicular, and these  deviations are
greater in proportion to the obliquity, with which the ray
strikes the surface of the transparent body.
   This phenomenon, which is known as the refraction of
light, is  easily understood.   It is owing to this change in
the direction of the luminous rays, in their passage from
water into  air,  that a straight stick,  plunged  half its
length into the former  liquid, always appears as if bent
at the point of immersion ; and        Fig. 36.'
if a piece of money (a) be placed
at the bottom of an empty vase,
and  the edge  of  the  latter  be
raised just  high enough to pre-
vent the eye of the observer from
perceiving this  object, to render
it visible, it will  be sufficient, to fill  the vase with water.
For the  ray of light  coming from the  money, instead of
always advancing in  a  straight  line, will  be refracted in
its passage from the water into  air,  and will depart from
the perpendicular; and by this  change in direction, the
rays,  which before passed above the eye of the observer,
will strike upon it.

  1 From the position of the eye it Is evident that if the light travelled in
a straight line, the observer could perceive the piece of money (a) only so
long as the ray a, c, reached his eye; but the walls of the base being opaque
this ray and all others situated below the line a, b, and a, c, are intercepted.
Now when the vase is filled with water the  rays are refracted in passing
from this liquid into the air, and consequently, one of the rays which before
passed  above the eye, the ray a,  d, for example, will be deviated so as to
reach the observer.
                    26
 
202
ANATOMY AND PHYSIOLOGY.
   The  luminous rays,  we  have observed,  approach the
perpendicular at the point of contact, whenever they pen-
etrate obliquely a body denser than that from which they
issue.   Therefore, the form of bodies exerts a  great in-
fluence upon the  course of the light  traversing them ;
and as their surface  is convex or concave, these  rays will
be collected or dispersed.
   Some examples will render this proposition easy to be
understood.   Let us suppose three diverging rays to set
out from the point a, traverse the air, and fall upon a lens
with a convex surface,  represented by the  line  b.   The
              Fig.  37.              ray a c, will  strike
                  ''       *         perpendicularly  up-
                                   on this surface, and
                     '■^rrr          consequently   will
        ^__^—-—""  / \       —f traverse the  lens
 a<\~---------—f.....................................c  without experienc-
         "~^-~^^^   \               ing any deviation;
                    /^^          but the ray a d, fall-
                        I       .....g ing obliquely upon
                 ^      *          this surface, will be
refracted, and approach  the  perpendicular drawn to  the
point of immersion ; now this perpendicular will take the
direction of the dotted line e, by approximation to which,
the luminous ray, instead of following its course towards
the point d, will follow  the  line /.   The  same  will be
the case with the ray a g, which in continuing its course
will approach the perpendicular h, and be directed towards
the point i, instead of continuing in a straight line towards
the point g.   The other rays, which strike upon  the lens,
will  be refracted in  an  analogous manner,  and,  conse-
quently, in the  place  of being  dispersed,  they  will be 
FUNCTIONS OF RELATION.
203
collected and may even unite in one point, which may be
called the focus of the lens.
   If the surface of the crystal, in place of being convex,
is  concave,  the luminous rays  will  not approach  the
axis of the bundle,                p^  go
as in the preced-                   j            e
ing  case, but, on                      -^    /\^^
 ,              ...                      ^"\  ■■f^\......d
the contrary, will                   ________—~?\
greatly  diverge.  ^__r——-------        ''    \
The  ray a d, for------—~~^_l
example,   must                         / ~^r~^ f
approach the per-                                    j
pendicular at the
point of contact,  which will have  the direction of the
dotted line e, and by this  deviation  the ray will take the
direction of the line f.
   The refraction of the luminous rays, in thus traversing
convex or concave lenses,  is greater in proportion  to the
curvature of the  surface of these bodies, and the mere
inspection  of the  figures  we have made  use of will  be
sufficient to make us comprehend it must be so.  For the
greater the curvature of the surface upon which the di-
verging rays strike, the more will the perpendiculars, at
the point of immersion, depart from these same rays.
   Physics also teach us that transparent bodies refract
the light more  powerfully  in proportion to their density,
(that is to say when under the same volume they have a
more considerable  weight), and  when formed of more
combustible materials.
   The light which strikes a transparent body does  not
entirely traverse it; a considerable  portion is reflected,
and owing to this property, bodies  answer more or less
perfectly the purpose of mirrors. 
204           ANATOMY AND PHYSIOLOGY.

iigh?Xeye!  From what precedes, we see that when a col-
lection of luminous rays falls  upon  the cornea, one part
must  be reflected while the other  traverses it.   It  is the
light  thus  reflected, which  gives  to the eyes their bril-
liancy, and which causes our own image in the eyes of
others.   The rays, which penetrate into this transparent
plate, pass into a body much denser than the  air;  they
are, consequently, refracted and approximated to the per-
pendicular or axis of  the  collection, the more forcibly in
proportion  to the convexity of the cornea ; for the greater
the projection of this membrane,  the more acute will be
the angle formed by  the diverging rays striking upon its
surface.
aqueous humor!  If> aner having  traversed the cornea, the  lu-
minous rays entered  the  air, they would  be refracted to
the same degree as upon their entrance into this  mem-
brane, but in a contrary direction  ; they would conse-
quently retake their  primitive  direction.  But the aque-
ous humor which fills the anterior  chamber of the eye,
possesses a refracting power much  greater  than the air,
so that on entering  it the  rays are  less dispersed, than
they  were approximated by  their  passage  through the
cornea;  the action of these parts  therefore renders them
less divergent than before  their entry into the eye, and
causes a more considerable  quantity of light to pass into
the opening of the pupil.
  UsePupiiUie   A great part of the  light, which arrives at the
bottom of  the anterior chamber of the  eye, meets the iris
and is absorbed or reflected outwardly by it:  that only,
which falls upon the pupil, penetrates to the  bottom of
the eye, and the quantity is in proportion to the size of
the opening.  Thus when  but  a  small quantity of light 
FUNCTIONS OF RELATION.
205
reaches the eye, the  pupil is dilated, while it contracts
under the influence of a  brilliant light;  the  iris, as Ave
see, regulates the quantity of light reaching the retina.
   The rays of  light having traversed the pupil, Systamnef
fall upon the crystalline lens, which is diaphanous, and
which  changes  anew  their direction, causing them all to
converge to one point, called the focus, where they unite.
Now this focus  is precisely upon the surface of the retina,
and it is thus that the luminous rays, sent to the eye
from different points of a body placed at a  distance, are
collected upon this nervous membrane so as to paint upon
it, in miniature, the object from which they  emanate.
   It is easy to  be convinced by experiment that  Formation
          •'                 j   i            of images upon
images are thus formed  in  the bottom  of  the the reti"a-
eye.   Take the eye  of a hare or pigeon, the sclerotica
of which is nearly transparent, or better yet, the eye of
an albino, and  place in front of the cornea a  very brilliant
object, a lighted candle, for example, and the image of
the latter will be seen depicted upon the retina.
   These  images  are al-           Eig. 39.
ways formed upside down,
and the cause of this  phe-
nomenon is easily shown.
When  we consider the course  the luminous rays, origi-
nating from the two extremities (a, c,) of an object, must
take to reach the retina, it will be seen they must  cross
before  reaching it, and that consequently the ray coming
from the superior extremity (a), of an object will be at
the lower part of the  space occupied upon the  retina  by
the entire collection of rays forming the image (6), while
that coming from the inferior extremity of the object (c)
will occupy the top of the same  space (d).    The  same
 
206
ANATOMY AND PHYSIOLOGY.
will take place with all the other rays, and therefore the
object will appear reversed at the bottom of the eye.
 Uchorow!le    The black matter, which  is  situated behind
the retina, and which lines the whole bottom of  the eye
as well as the posterior face of the iris, serves  to absorb
the light immediately after  it has traversed  the retina.
If this light were reflected in other points of  the mem-
brane, it would considerably trouble the sight, and  pre-
vent the  clear formation of images on  the bottom of the
eye.  Thus in albinos, whether man  or animal, where
this pigment is wanting, vision  is extremely imperfect;
during the day they can scarcely see at all.
 Pertheeye.of  The globe of the eye serves to conduct the
light and to concentrate it upon the retina.  It discharges
the office of a kind of spectacle-glass, but it is  an optical
instrument far more perfect than any of those ever  yet
constructed by scientific men : for at the same time that
it is perfectly achromatic and presents  no aberration  of
sphericity, its capacity may vary considerably.
 Achromatism.  By achromatism is meant the property of turn-
ing light from its course without developing any color,
and, consequently, the achromatic lenses are those which
form in their foci colorless images, or possessing only the
colors of the object represented.  The white light results
from the union of the  seven colored  rays  of the  solar
spectrum, and these different rays are not equally refran-
gible.  Wherefore, when light is passed through  a re-
fracting body, it is more or  less completely decomposed,
and the objects whence it proceeds, appear to have the
color  of the solar  spectrum.   Achromatic telescopes are
obtained  by combining several glasses, some  of which
correct the dispersal of the light produced by the others, 
                FUNCTIONS OF RELATION.            207

so as to unite in one focus all the rays.  It is  probable
the achromatism of the eye depends upon  a similar ar-
rangement, but physicians have not  yet agreed upon the
explanation of this phenomenon;  some think it depends
upon the different humors of the  eye, others attribute it
to the difference of density in the different layers of the
crystalline lens.
   The aberration  of sphericity consists in the AJEcitny.of
union of rays which fall upon different parts of a lens,
into foci  sensibly  different,  whence results a  want of
clearness in the images.   When the lenses are very  con-
vex, the rays which pass  near the edges do not unite in
the same  focus with those  which  traverse the central
part of the instrument, and  to  obtain clear images, the
passage of the former must be intercepted by placing in
front of the lens a separating medium pierced by a hole.
Now, the images formed  behind  the crystalline lens of
the eye are never diffused, and this want of aberration of
sphericity has been attributed to the iris, which answers
the purpose of the divisions in the interior of telescopes.
   Every one knows that  objects may be  seen with  the
same clearness when placed a few inches from the  eye,
as when at a considerable distance from this organ.   In
our  optical instruments, on the contrary, the  intake
formed in the focus  of a  lens  advances or recedes, ac-
cording to the distance of the object.   It has, therefore,
been  supposed that to give to our  sight such varying
capacity, the  crystalline lens must  approach or recede
from the retina as necessity required, or else the globe of
the eye must change its  form.  But direct observation
does not confirm  these hypotheses, and this peculiarity
has never found a satisfactory explanation. 
208           ANATOMY AND PHYSIOLOGY.
   However, the eye does not always possess in the same
degree  this  precious faculty ; some can  see  distinctly
only at  the distance of some feet; nearer all images are
confused.  With others, on the contrary,  the sight be-
comes clear only when  the objects are brought within a
few inches  of the eye, and  every thing  beyond  seems
enveloped in a cloud.
  Presbytia.  The former  of these infirmities, known as
presbytia, depends upon a want of convergence in the
collections  of rays traversing the  humors of the eye.
The rays which arrive at this  organ  from  a very distant
object, diverge very little and may be collected at one
point of the retina, although the refracting power of the
eye be small; but those which come from  a  near  object
diverge greatly, and the refracting  power  of the eye  is
too weak to  collect them upon a determinate  point of
the retina.   Those thus afflicted  have  usually a con-
tracted pupil, as if they  were continually making an effort
to prevent  any other rays from entering  the  eye than
those falling upon the centre of the crystalline lens, and
which do not require great deviation from their course to
be  collected  together behind it upon a fixed point of the
retina.   This want of  refracting power in the  eye ap-
pears, in general, to belong to a flattening  of the cornea
or  crystalline lens, which circumstance   must tend to
produce presbytia, and  which  may be found in  nearly all
old men.
  Myopia.   Myopia is the result of a contrary effect.  The
rays which traverse the eye are then so forcibly deviated
from  their  course,  that in place of diverging they even
converge before reaching the  retina.  This imperfection
of  the visual organ depends, in general, upon too great a
convexity of the cornea or crystalline lens. 
FUNCTIONS OF RELATION.
209
   It is remarked that short-sighted persons become less
so by age, which happens in consequence of a diminution
in the secretion of the humors of the eye always occur-
ring in old age, which, by rendering the cornea  less con-
vex, renders  the sight longer; in most  cases,  it causes
presbytia, but here it only serves to correct the errors of
the  eye and  to  give to the sight its  usual  character.
Therefore  the vision of short-sighted  persons is improved
by age, while in  others  it is  usually weakened; but  as
this  diminution in the abundance  of the  humors of the
eye always continues,  there is a moment when the eye of
the short-sighted individual becomes also too much dimin-
ished in the  power of refraction,  and his sight, conse-
quently too long.
   To  correct these natural faults of the eye, recourse
must be had to means, the efficacy of which confirms the
explanation just  given of the cause, whether of myopia
or presbytia.   Glasses are therefore  placed before  the
eyes with surfaces so directed as to augment or diminish
the divergence of the rays traversing them.  Short-sighted
persons make use of concave glasses, which give diverg-
ence to the rays of light, and the far-sighted employ con-
vex, which, on the  contrary, collect the rays  diverging
from the axis of the bundle.
   The contact of light with the retina, we have  UsereunaUie
said, causes vision, and when this membrane is paralyzed
(a condition which constitutes the disease known as gutta
serena),  this  sense  is completely  destroyed.   But the
sensibility of  the  retina is entirely  limited, and  can  only
be excited by this subtile  agent.  This  nervous mem-
brane enjoys  little or  no sensibility to the touch, and it
                   27 
210
ANATOMY AND PHYSIOLOGY.
may be touched, pinched, or even  torn  upon the  living
animal without the slightest manifestation of pain.
   However, this peculiar  sensibility of the retina  has its
limits: too feeble a  light does  not  act  upon  it, and  too
strong a light  injures it and renders  it incapable of  action.
But, in this respect, the  influence  of habit is extreme;
when  a person  has remained  sometime in obscurity, a
light, although very feeble, dazzles the eyes, and renders,
for some  instants,  the  retina  incapable of  discharging
its functions, while those  accustomed to  the light of day
experience the same effects only when looking upon the
most brilliant objects, in  seeking, for example,  to take the
sun's altitude.
   When we look for a  long time upon  the same  object
without a change of position, the point  of the retina re-
ceiving the  image is soon  fatigued, and  this fatigue, car-
ried beyond a certain limit, deprives for some time, the
part, experiencing it, of its usual sensibility.  Thus, if we
look for some  time at a white spot on a black ground, and
then change our sight to a white ground, we think we see
a black spot, because the point of  the retina  already fa-
tigued by the white  light has become insensible to  it.1
   The fatigue experienced by the  retina in the exercise
of its functions depends in part upon the efforts made to
fix the attention upon the object placed  before the eyes.
If we  endeavor to examine attentively bodies in a feeble
light, we soon experience a painful  sensation in the orbit,
and also in the head.

  1 The black color depends upon the absence of light, and the bodies which
afford it to us are  those which absorb all the light falling upon them ; we
perceive them only because they are surrounded by bodies which reflect
them. 
FUNCTIONS OF RELATION.
211
   All points of the retina  are  adapted to receive the im-
 pression of light;  but the central part of this membrane
 enjoys a more exquisite sensibility than the rest, and it is
 only when the images of external objects are formed upon
 this part, that we see them distinctly.   Thus, when look-
 ing at  any object, we take care  to direct toward it the
 axis of  our eyes.
   We might attain the same end by means of the various
 movements of which the head is susceptible;  but, in or
 der to render these  changes  in the direction of  the  eyes
 more easy, nature  has provided these organs with muscles
 destined especially for their motion.
   These muscles are  fixed  to  the sclerotica  by ^hecleeyse?f
 their anterior  extremity,  and  inserted by their  opposite
 behind  the  globe  of the eye
 (to  the  bottom of the orbit),
 and, since  this organ reposes
 upon fatty cellular tissue, with-
 out intimately adhering to it,
 each  of these  muscles  by
 contracting, turns  the  eye to
 its own side.   They are six
 in  number:  four  of  them
 called recti  muscles, inserted                         d
  1 Vertical section of the orbit to show the position of the eye and its
 muscles.—a,  Cornea, — b, sclerotica, — c, optic nerve,  the opposite ex-
 tremity of which enters the globe of the eye, — d, rectus inferior muscle of
 the eye, — e, rectus superior muscle, —/,  portion of the rectus externus
 muscle of the  eye; at the bottom of the orbit we see the other extremity
 of this muscle, of which the entire middle  part  has been removed to dis-
play the optic nerve situated behind it; — g, extremity of the small oblique
muscle, — h, large oblique, the tendon of which passes into a small  pulley
before it is fixed to the sclerotica, — i, elevator muscle of the  superior eye-
lid, —k, lachrymal gland.
 
212
ANATOMY AND PHYSIOLOGY.
in the four opposite points  of the circumference of the
sclerotica and proceed directly backward, so that they can
direct the eye upwards, downwards,  to  the right or left,
depending upon the muscles called into action.  Lastly,
two of these muscles which are called the oblique muscles,
(h, g,) are so arranged as to cause this organ to  execute
movements of rotation, which direct the pupil downwards
and inwards, or upwards and outwards.
nerJveesSof0tneheeye. The nerves, which give motion to these mus-
cles, belong exclusively to the apparatus of  vision.   They
are furnished by the third, fourth and sixth pairs.  (Fig.
29).   The recti muscles  are  entirely under the direction
of the will;  the oblique  often act independently  of it,
and from their contraction arises the rolling up of the eyes
in syncope.
   The optic  nerve, which, by its expansion on the bot-
tom  of the eye, forms the retina, transmits to the brain
the impressions produced upon this membrane  by  the
contact of light: its section therefore produces total blind-
ness.
   In order that the retina may discharge its functions re-
quires not merely the consent of the optic, but also of the
nerves of the fifth  pair, which  we have already seen exer-
cises the greatest influence upon taste and  smell.   If the
section of this nerve be made between the brain  and the
point of origin of the branches to the eye, vision is  de-
stroyed.   The  animal  appears to distinguish light  from
darkness, but is really blind;  and singular though it be, at
the end of some time the cornea  becomes opaque, ulce-
rates, the eye is emptied and atrophied.
  of "images"   The hemispheres of the brain appear to be the
seat  of the perception of these sensations, as of all others ; 
FUNCTIONS OF RELATION.
213
for when they are destroyed the animal becomes at once
blind.  But there are other parts of the encephalon which
also exercise great  influence upon this sense;  these are
the optic lobes, or  tubercula quadrigemina (fig. 29, g,).
When destroyed in a bird (where these parts are much
developed), blindness will also ensue ;  and it is  worthy of
observation that animals in whom the retina is most de-
veloped and the optic nerves the largest, are also those in
which these lobes acquire the most volume and have the
most complicated structure.  These organs may even be
considered as depending  upon the  optic nerve, and as
being  the uniting bonds of these nerves to the cerebral
hemispheres.
   But the most striking result of our experiments upon
the encephalon is  to  find, that  the destruction  of the
cerebral  hemisphere or optic lobe of one side does not
occasion the loss of sight of the same side: the  eye of
the opposite side becomes blind, and anatomy explains
this fact; for  the optic nerves soon after their separation
from  the brain, unite and  interlace so  that the one  fur-
nished by the right lobe goes  to  the left eye, and vice
v^rsa.
   We judge of the  form of bodies by that of the  ^™ts°.f
image they produce upon our retina; therefore,  when,
from  any cause, the form  of the luminous pencil of rays
sent by them to this membrane, is changed before  reach-
ing the eye, we fall into great errors  in  our judgment.
The  experiment already cited of a stick half plunged
into water and  then appearing  bent, although actually
straight,  is an optical illusion of this kind.
   We judge of the position of surrounding ob- ^Jects.^
jects by the direction of the luminous rays they send to 
214
ANATOMY AND PHYSIOLOGY.
 us, and we  always see them in the extension of the
 straight line  followed by these rays at the  moment they
 penetrate the eye.   For this reason, when the pencil  of
 rays sent by  one of these objects upon a  polished surface
 (a mirror, for example,) is reflected by the  latter so as  to
 make a greater or less angle and arrive  at the eye, we
 see the object as if it were  placed behind  the  mirror,  in
 the prolongation  of the straight line pursued by the ray
 meeting the  eye  from this instrument.   Judgment may
 rectify the consequences we draw from  this sensation;
 but it always exists.
   This accounts for our using but one eye when we wish
 to be certain that bodies are in an exact line with each
 other.   When this  condition is actually fulfilled, and one
 of our  eyes  placed upon the  prolongation of the line
 occupied by  these  objects, the  luminous  ray which  is
 directed from the  more distant  body towards our  eye
 cannot arrive to it,  being intercepted by  the intervening
 body, and so of  the rest, consequently the  nearest body
 conceals from us  entirely or  in part all the others; when
 if regarded by both eyes, the same  thing  happens only
 when the objects are so far distant from us  that the rays
 sent to our eyes are almost  parallel, or when the  inter-
 vening object is very large in comparison with the more
 distant or very near to it, and even then  the coincidence
 is much less plain than  if the observer uses but one  of
 his eyes.
  "£1!of   To estimate the distance, which separates us
from objects,  the  simultaneous action of the two eyes is,
on the contrary, of great assistance : the following experi-
ment will convince  us of the fact.  Suspend  a ring by
a thread, and try  to introduce a pointed instrument fixed 
                FUNCTIONS OF RELATION.            215

 to the end of a long stick; by making use of both eyes
 you will easily succeed at every trial; but if one eye be
 closed  you will find the  greatest difficulty in  threading
 the ring : the instrument will go beyond or stop  short,
 and only by chance or after repeated trials will you suc-
 ceed in introducing it into the ring.
   Thus when an individual has lost one eye he generally
 remains some time unable to judge correctly of the dis-
 tance of bodies situated near him, and this privation ren-
 ders the appreciation always much more difficult.
   But the utility of the two  eyes in this case  is easily
 explained upon physical laws.   When an object is only
 a short distance from us, it is  requisite, in order that its
 image may fall upon the same point of the retina of the
 two eyes, that the axis of these organs should converge
 toward the point looked at, and this inclination, of which
 we are conscious, is great according to the  proximity of
 the object.   But when objects are so far  distant that in
 beholding them the optic axes of the two eyes become
 sensibly parallel, we have no longer a sure rule to deter-
 mine their distance, and we can only form our judgment
 from data more or less deceptive, such  as the degree of
 light, the clearness with which we distinguish the minu-
 tiae, the size of the object itself, our previous  acquaint-
 ance  with it, etc.   When we  can  compare this  distant
 object with those intervening, this appreciation becomes
 much more certain ; every one knows how difficult it is
 to judge of the distance of a  light seen in the middle of
 the night, when the obscurity prevents surrounding ob-
jects  from being seen.
  The concurrence of the two eyes is moreover essential
 in that it makes objects appear plainer.   If we regard a 
216
ANATOMY AND PHYSIOLOGY.
strip of white paper with one eye, and place  before the
other an obstacle which will conceal half the  object, the
portion seen by both eyes, at the same time, will appear
much more brilliant than when seen by one alone.
  size of objects.  The manner in which we judge of the size
of bodies  depends much more upon intelligence and cus-
tom, than upon the action even of the apparatus of vision.
Our first guide is really the size of the image formed at
the bottom of the eye ; but as the distance between  us
and an object increases, this image diminishes, so that to
judge of the dimensions of the former, the distance at
which we suppose it must always be considered.  When,
therefore, the distance  is not exactly appreciated, it is
difficult to judge of the size of a  body seen for the first
time.  A mountain, which we see afar off for the first
time, appears to  us, in general, much  smaller than it
really is, because we imagine, it near us, when it actually
is at a considerable distance.
  Mobjenctsof   The estimation  of  the motion of bodies is
sometimes made from the change of direction of the light
which arrives at the eye, whence results the displacement
of the image upon the retina, sometimes from the varia-
tion in  size of this same  image.  In order to follow the
motion of  a body its displacement must not be too rapid,
for  then we  do not perceive it unless it project a very
great quantity of light, and, in this case, the same  effect
is produced upon our eyes as if it instantaneously occu-
pied the whole length of the line traversed.   On the con-
trary,  we  generally recognise with great difficulty, and
sometimes we even cannot recognise the motion of bodies
the image of which is  very slowly displaced, either from
the actual slowness of their motion, as in the hand of a
watch,  or from their great distance, as in the stars. 
FUNCTIONS OF RELATION.
217
   From the remarks  made with regard  to the  Education of
                                   c           the sense of
manner in which  we  judge of the  distance and slsl,t
size of bodies, it  is easy to see that the sense of vision
has need of a kind of education, and that under some
circumstances  it will always lead us into error.
   It is by making use of these errors, known in physics
and  physiology by the name  of optical illusions, as well
as of the laws of  the  animal economy on which  they de-
pend, that the arts  are able to produce  them at will, to
make plane surfaces appear round and prominent, and to
make near objects more or less distant.
   That  sight may give us the valuable information  it is
susceptible of communicating, this  sense must  undergo
long exercise and a thorough  education.  The new-born
infant distinguishes only the light from the darkness ; and
although its eye already presents all the physical qualities
necessary to vision,1 it does not begin to see till after some
weeks of existence.   At first  its eyes are  only directed to
the most brilliant  objects, such  as  the  sun, etc., without
distinction.   The first things which  attract it  are those of
a red color; it soon,  however, begins  to  distinguish  the
other brilliant colors, but has,  as yet, no  idea of distance
or size, and it  will extend its hand  to seize  upon remote
objects, without the least regard to their dimensions.  By
degrees  vision is perfected, and it is principally in correct-
ing, by  the aid of the other senses, the  errors  to which
the former is exposed  that the infant acquires the faculty
of judging rightly of what he  sees around him.

  1 In the fcetus prior to the  seventh month, it is otherwise; the iris has
not yet been perforated; but at this period the pupillary membrane, which
occupies the place of the pupil, breaks  and is absorbed so as to give access
to the light.
                    28 
218
ANATOMY AND PHYSIOLOGY.
  To give some idea of the kind of education necessary
to vision, it will be sufficient to read the curious history
of a man blind from his birth, to whom  Cheselden, a
celebrated English surgeon, restored sight at a sufficiently
mature age to enable  the young man  to analyze all his
sensations, and give an account of them.
  " When he first saw, he was so far  from making any
judgment about distances,  that he  thought  all objects
whatever touched his eyes (as he  expressed  it) as what
he felt did his skin, and  thought no object so agreeable
as those which were smooth and regular, though he could
form no judgment of  their shape or guess what it was in
any object that was pleasing to him.   He had during his
blindness such feeble  ideas of colors as he could distin-
guish by a strong light, but they did not leave sufficient
traces to be recognised;  when he  did  see  them he said
the colors he perceived were not the same he formerly
saw.  He knew not the  shape of any thing, nor any one
thing from another, however different in shape or magni-
tude : but upon being told what things were, whose form
he before knew from feeling, he would carefully observe,
that he might know them again;  but having too many
objects to learn at  once, he forgot many of  them ; and
(as he said) at first  he learned to know and again forgot
a thousand things in a  day.   More than two months
elapsed  after  the operation, before he  could  be made to
comprehend that pictures represented solid  bodies, when
to that  time  he considered them only as  party-colored
planes,  or  surfaces diversified with  a variety of paint;
but even then he was no  less surprised, expecting the
pictures would feel  like the things they represented, and
was amazed when he found those parts, which by their 
FUNCTIONS OF RELATION.
219
light and shadow seemed round and uneven, felt only flat
like the rest, and asked which was the lying sense, feel-
ing, or seeing ?
   " Being shown his father's picture in a locket  at his
mother's watch, and told what  it was, he acknowledged
a likeness, but  was vastly surprised ; asking how it could
be, that a large face could be expressed in so little room;
saying, it should  have seemed as impossible to him, as  to
put a bushel of any thing into a pint.
   " At first, he could bear but very little light, and the
things he  saw he  thought extremely  large ; but upon
seeing things larger, those first  seen he conceived less,
never being able  to imagine any lines beyond the bounds
he saw.   And now being lately couched of his other eye,
(more than a year after the first operation), he says, that
objects at first appeared large to this eye, but not so large
as they did at first to the  other;  and looking  upon the
same object with both eyes, he  thought it  looked about
twice as large as with the first couched eye only, but not
double,  that we can any wa}7s discover."
   When we began the  study of  vision it  was f^Ky^.1"
with the remark,  that the apparatus charged with the ex-
ercise of this sense was composed of an  essential part,
the globe  of the eye and optic  nerve, and of various
accessory parts destined to move or to protect the former.
Enough has been said upon the  structure  and  functions
of the eye itself, and  also of the muscles which are fixed
to it: to close the history of this function, we have only
to describe the  protecting parts of this organ.
   The first objects  of interest are the bony cavi-  orbit.
ties,  which lodge the eyes and are  called the  orbits.
These are deep holes hollowed in the face  and  bounded 
220           ANATOMY AND PHYSIOLOGY.
                           by the several  bones of the
                           head.   They are very large?
                           and  have  nearly  the  form
                           of a cone,  with the base di-
                           rected outwards,  and  apex
                           towards  the  brain, which is
                           pierced  by a  hole  for the
                           passage  of the optic nerve.
                           In man and monkeys the or-
                       P   bits  are directed  forward,
and their external wall separates them completely from
the temporal fossa?;  but if we examine  animals gradually
differing in an increased ratio from these, the  orbits will
be found to  become more and more lateral, and  to be
more  intimately confounded with the  above mentioned
fossae.
  But  the globe of the eye  is separated  from  the bony
walls of  the orbit by its muscles, and by a great quantity
of fatty cellular tissue which surrounds it, as  an  elastic
couch.
  In front, the eye is protected by the eyebrows, eyelids,
and by a peculiar liquid, the tears, with which its surface
is always bathed.
 Eyebrows.   The eyebrows are transverse eminences formed
by the skin, which in this point is supplied with hair and
provided with a special  muscle of motion.   They serve
to protect the eye against external  violence, to  prevent
the perspiration flowing from  the forehead from irritating
the surface of this organ, lastly, to protect it from the im-
pression  of too strong a light, especially when  the latter
comes  from an  elevated place.
 Eyelids.    The eyelids in man, and all other  mammiferae, 
FUNCTIONS OF RELATION.
221
are two in number situated one above the other, and  for
this reason divided into superior and inferior.  They are
a kind of movable veil placed in front of the orbit and ac-
commodated in form to the globe of the eye, so that being
closed they  completely  cover the  anterior  face  of this
organ.  Exteriorly, they are formed by the skin which at
this place is very fine, semi-transparent, and sustained by
a fibro-cartilaginous  plate (the tarsal  cartilages).   Their
internal face is lined by a mucous  membrane, called the
conjunctiva, which is reflected upon the globe of the eye,
covers the whole  anterior part of the sclerotica, and is
confounded with the transparent cornea.   The free bor-
der of the eyelids is supplied  by a range  of hairs, having
behind them  a series of holes which communicate with
the glands of Meibomius, follicles lodged within the  tarsal
cartilages and secreting a peculiar humor, which, when
thickened and dried, as often happens in sleep, is  known
as the wax.  Finally, there are within the eyelids muscles
of motion ; one of them surrounds the opening like a ring,
and contracts them with more or  less force (fig. 32, h);
the other extends from the superior eyelid to  the bottom
of the orbit, and serves to raise this veil, (fig. 40, i).
   The eyelids serve to prevent the access of  light to the
eye during sleep.  When awake,  they approach or sepa-
rate so as to allow only the quantity of light necessary to
vision to  pass, but not enough  to injure the retina.   They
also protect the eye from the  contact  of foreign  bodies
which are in  motion  in the air, preserve  it from shocks,
by their almost instantaneous  occlusion, and oppose the
effects of the prolonged contact of the air by continual
motions,  which return at nearly regular intervals.
   One of the uses of the conjunctiva is to facilitate  winking. 
222
ANATOMY AND PHYSIOLOGY.
the operation of winking.  This membrane, with  an ex-
quisite  degree of  sensibility,  secretes  a humor which
increases the polish of its surface, and renders  the  con-
stant friction of the pallebral, upon the occular portion of
the conjunctiva, much more easy; but this liquid is not
alone sufficient for this effect, and  in order that  the  con-
junctiva may properly discharge all its functions, its sur-
face must be lubricated by the tears.
  Tears.     This humor, composed of water,  holding in
solution some thousandths of  animal matter, and of  salts
met with  in all the  liquids  of the animal economy, is
formed in a large gland, situated in the vault of  the orbit,
behind the external part of the border of this cavity and
above the globe, (fig. 40,  k).
 apparatus!1    This lachrymal gland sheds the tears upon the
surface of the conjunctiva by six  or seven  small  canals,
which open upon this membrane, on the  superior and ex-
ternal part of  the upper lid.   The tears afterward spread
over the whole surface  of the  conjunctiva, preventing its
desiccation  and forming a uniform layer, wdiich  gives to
the eye its polish and  brilliancy.  They must also serve
to prevent the evaporation of  the humors of the globe of
the eye, and that of  the  liquids moistening the cornea;
and it is  actually the case, that when after  death  tears
cease to be  diffused upon the surface of the eye, the latter
soon becomes flaccid, and the cornea loses  its transpa-
rency.
   The tears, which do not evaporate or are not  absorbed
by the conjunctiva, pass into the nasal fossae by  means of
canals, the openings  of which may be seen in  the  free
border of either lid, near the  internal angle of the eye, at
the point where these organs quit  the globe of the eye to 
FUNCTIONS OF RELATION.
223
pass to the caruncula lachrymalis, a projecting body of a
rose color, principally formed by a collection of small folli-
cles.   These two openings, styled lachrymal points, are
extremely narrow and communicate with very fine canals,
which are lodged in the interior of the lids  and directed
inward to empty into the nasal duct.  This latter  duct
extends from the  internal angle of the eye to the inferior
meatus of the nasal fossae, and to reach it traverses a bony
canal hollowed between the orbit and the nose.
   In  the ordinary condition,  the absorption of tears by the
lachrymal points takes place but very slowly ;  but when
the latter become very  abundant and roll in  the eyes,
their  passage into the nasal fossae becomes so rapid, that
the handkerchief is requisite at every instant.  Sometimes,
in certain lively emotions of the mind, for  example, the
secretion of tears becomes so very  abundant  that this
liquid runs over the eyelids  and falls upon the cheeks.
   Weeping may, also, depend upon another cause.  Some-
times there occurs an obstruction of the nasal canal which
prevents  the  tears from  reaching  the nasal fossae; this
liquid then flows  upon the  cheek and accumulates  with
so much rapidity in the   superior part of the obstructed
canal, that  a  considerable tumor may result, or even  its
walls  be ruptured and a fistula lachrymalis formed.
   The structure of the apparatus of vision  and   Apparatus
                                               of vision in
the mechanism of sight, are  nearly the same in  anima]s-
man  and  all  the  mammiferae,  as  in birds, reptiles  and
fishes.   The eye  of some of the mollusca, such as the
poulpe1 also resembles ours a little ; but in most animals

  1 This term is applied to such of the mollusca, belonging to the class
cephalopoda, as inhabit chambered shells ; the Nautilus, some of the
polypi,  etc., are examples. 
224           ANATOMY AND PHYSIOLOGY.

of this class and  in  the  arachnida, the  Crustacea and
insects, these organs have  scarcely any points  of  resem-
blance with the eyes of the superior animals.
    OF THE INTELLECTUAL  AND INSTINCTIVE
                    FACULTIES.

  We  have already seen how,  in  order that man may
have the knowledge of  the impression produced  by the
bodies  acting upon his  senses,  it is not  alone sufficient
that these parts be endowed with the faculty of feeling,
and that the sensations of which they are the seat  be
conveyed to the brain by the intervention of the nerves:
but that, in order to have the impression thus received by
the brain become a sensation of which we are conscious,
this organ  must  not remain passive,  but must perceive
and acquaint us with it.  And in very many cases a mul-
titude of impressions are received  by the brain without
any consciousness on our part.   In sleep,  for  instance,
we are ignorant of noise at our ears, or odors acting upon
the organ of  smell.  When awake, custom also renders
us insensible to  a  great number of  these impressions,
and when several strike us at the  same time, we may
even, sometimes,  by the mere effort of volition, abstract
ourselves from  some of them,  and only really perceive
those to which we wish to direct our attention.
Perception.    This faculty of perception, which, when excited
and directed  by the will, takes the name of attention, is
one of the attributes of the brain,  and exists only when 
INTELLECTUAL FACULTIES.
225
this organ is in activity.   The experiments, in which the
two hemispheres of the brain have been removed  in  liv-
ing animals, have already demonstrated, that the  loss of
these parts  rendered these beings insensible to all  im-
pressions received by the organs of the senses, and when
the brain is prevented  from discharging its functions,
either  by compression or  the administration of certain
poisons to the animal, as  opium, the  same  effect  is pro-
duced.  Different diseases of the  brain, also, render it
unsuited to perception, and when it  has been for some
time in a state of continual activity, it presents the same
phenomena with all  our  other  organs ;  it becomes fa-
tigued and cannot continue to discharge its functions, till
it has remained, for a longer or shorter time, in repose.
   Tlie  brain does not merely possess the faculty  Memory.
of perceiving  sensations  and thus producing what  are
called ideas, it is also capable of recalling  ideas already
acquired.   This  new faculty bears the title of memory,
and it is independent of perception;  for, in certain cere-
bral  affections,  we  find it completely lost without  de-
priving the  patient of the  faculty of  knowing what sur-
rounds him.  It is remarked that  the memory preserves
the clearest idea of the most lively impressions,  and that
this faculty, extremely developed  in  the early period of
life, is  weakened with the  progress of age.  In the aged,
memory is sometimes entirely lost, and in the adult it is
weaker than in the adolescent or child.   Therefore, at a
tender age,  such  knowledge is acquired  as does not  de-
mand great reflection, such as the languages, history,  the
descriptive sciences,  etc., exercise tends also to render it
stronger.
  But  memory can hardly  be considered a single faculty,
                  29 
226           ANATOMY AND PHYSIOLOGY.

and a multitude of facts go to show that there are, so to
speak, as many distinct memories as there are orders of
different faculties of the mind.   There is  a  memory of
words, of forms, of places, of music, etc., and  it is very
rare that a man possesses them all in  the  same degree ;
in general one of these faculties predominates, and in cer-
tain cases of mental disease, one of them has been com-
pletely lost, while the other kinds  of memory were not
sensibly weakened.
Reasoning, etc.    Acquired ideas do not remain isolated in the
mind:  we  possess  the  power of  comparing  them, of
seizing upon their respective relations, of drawing  from
them conclusions, and, in a word, of exercising our judg-
ment upon  all we  perceive.  The  faculty of forming a
succession of judgments which are chained  to each other,
or of reasoning, is one of  the most  precious attributes of
man.  But the peculiar characteristic  of human intelli-
gence, and, that which permits him to acquire the prodi-
gious development manifested by him in civilized nations,
is the faculty of generalization, which consists in creating
signs to represent ideas, to think by means of these signs,
and to form abstract ideas.
   instinct?.   Finally, it would appear  that, upon the action
of the  encephalon depend the inclinations or instincts,
which induce man and animals to execute certain deter-
minate actions, and to prefer certain  sensations to those
of another order.
 twelfth" de-   ^ *s remarked that an organ acts  powerfully
 rteTStaand in proportion to its volume.   It might then be
the intellectual        •_  _    ,        . ,           ...
 faculties.    supposed, that there would be a certain relation
 between the development of the encephalon and that of
 the intellectual or instinctive  faculties, which appear to 
INTELLECTUAL FACULTIES.
227
 have their seat in it; and when  man  is compared with
 other animals, his brain is generally found to be propor-
 tionally more voluminous.   It is,  also, remarked, that an-
 imals which display the most intelligence, monkeys for
 instance, have this  organ  very large, while in  the more
 stupid, as fishes, it is always extremely small.
   These facts have led to the inference that we Facial angle.
 might judge of the degree of intelligence of animals, and
 even of man himself, by the greater or less development
 of their brain; and to appreciate these  differences, vari-
 ous methods have been resorted to, the mpst celebrated
 of which is the measure of the  facial angle, proposed by
 Camper, a skilful Dutch naturalist.
   These measures serve  to point       Fig. 41.
 out the relation existing  between    «
 the volume of the  cranium (which   '\/^^~\  *v\>//'
 is filled  by the brain  and cerebel-    f^!_£^%   W-
 lum), and that of the face, and  are
 taken in the following manner.   A  (
 horizontal line (c, d), is drawn on
 a level with the auditory hole and
 floor of  the nasal fossae, so as to follow nearly the  direc-
 tion of the base of the cranium ; a second line is then
 let fall upon this (a,  b), which  touches the most promi-
 nent point of the forehead and the extremity of the  upper
jaw.  Now, it is evident that this latter will be inclined
 upon the former, and will form  with it an angle so  much
 the  more acute, as the face is  more developed and the
 forehead retreating, and that, consequently, the measure
of the facial angle (for  so the  angle of which we  have
just been speaking is called), may indicate with sufficient
accuracy the relation sought. 
228
ANATOMY AND PHYSIOLOGY.
       ,-,.   An         Man  is  of all  animals  the one
       Fig. 42.
        a            with the facial angle most open, and
       /^-T~~-^.      in this  respect  there  exist  great
      jUj0^\   \    differences among the different hu-
  c j^^^?Mh?^y  d  man races*  European  heads are
   /1I!^_/          usually  about 80° (fig. 41), and ne-
   1                  groes about  70°  (fig. 42); in the
 different monkey tribes it varies  from  65° to 30°, and
 becomes yet more acute as we depart from man and de-
 scend in the series of mammiferae ; in the  horse, for ex-
 ample, the forehead is  so retreating that it becomes im-
 possible to draw a straight line from the extremity of the
 superior jaw to  the cranium, on account of  the projection
 of the nose, as any one will soon be convinced by casting
                                his  eyes upon  the an-
                                nexed figure; finally, in
                                birds, reptiles and fishes,
                                the facial angle, when it
                                can be measured, is more
                                acute than in the mam-
                                miferae.
   The greater or  less coincidence which exists in gene-
 ral between the inclination of the facial line and  the ex-
 tent of the intellectual  faculties, does not appear to have
 escaped the observation of the  ancients ;  not only have
 they truly  remarked that the  open angle was a sign of a
 more generous nature and one of the characteristics of
 beauty, but in the figures of their heroes and  gods, they
 have advanced the facial line  more than it is in man, and
 in some statues  (that of Jupiter Olympus,  for example,)
 they have inclined it a little forward.1
  1 It is possible, however, that this manner of representing the Divinity
arose from another cause, and was independent of any idea of a relation
 
INTELLECTUAL FACULTIES.
229
    Most persons are accustomed to attribute stupidity to
 men and animals with retreating foreheads, or projecting
 snout; and when by any circumstance the facial line is
 raised, even without augmenting the capacity of the cra-
 nium,  we find, in animals which present this disposition,
 a peculiar air of intelligence, and we are induced  to at-
 tribute to  them  qualities  they do  not actually possess.
 The elephant  and owl are  examples, and this  is caused
 by the great extent of the  frontal  sinuses giving to their
 forehead  a considerable prominence.  The owl, as  every
 one knows, was with the ancients an emblem of wisdom,
 and the elephant bears in the  Indies a name which sig-
 nifies that he partakes of reason, and yet neither of  these
 animals is actually remarkable for the development  of its
 intellectual faculties.
    However, we must beware of attaching too much im-
 portance  to  these  measures; they can  give at  the  most
 but a proximate idea of the development of the brain,
 and as yet there is no proof that the extent of  the  intel-
 lectual faculties is proportional to this material develop-
 ment of the encephalon.
   We  have already  seen that  the  brain is the  Doctor"1 Gaii.

between  the development of intelligence and the opening of the facial angle-
All people attach ideas  of beauty to the exaggeration of peculiarities of
structure characteristic of  their race; negroes esteem the  blackest skins
the handsomest; the inhabitants of Oceania, with remarkably flat noses,
think their beauty is increased by augmenting  the width of this part;  and
the Caraibs, with extremely retreating foreheads, compress the heads of
their children, to exaggerate yet more this characteristic disposition.  Now
one of the peculiarities of the Cossack race, and more especially  of the
Greek nation, is the slight inclination of the facial line, and consequently
from the  tendency  just observed the Greeks might naturally regard this
disposition as a condition of beauty, and think that to represent beings su-
perior to ourselves,  it must  be exaggerated. 
230
ANATOMY AND PHYSIOLOGY.
seat of many  very distinct functions, and  when  we ex-
amine the manner in which the intellectual faculties and
feelings are exercised in different men, we soon  observe
that a more or less increased development of one is not
always accompanied by an equal development of the rest.
A man, who shall be remarkable for the instinctive love
to his offspring, may have but very feeble intellectual
faculties ; and another, endowed with a most happy dispo-
sition for the sciences of calculation, may yet lack com-
pletely imagination,  or power of observation.
   These considerations and many similar facts, have led
some philosophers to consider the brain as a single organ,
all parts of  which concur in the  same manner to the pro-
duction of the phenomena of instinct and intelligence,
but that nature has established in the  functions of the
encephalon  the same division of labor that we  find in
the other apparatus of the animal  economy, when  the
faculties of the latter are perfected.   They have regarded
the feelings as having their seat in a determinate part of
the brain, the  intellectual faculties in another, and, in a
word,  each kind of function executed  by the brain as
the result of  the action of an instrument  or particular
organ, and that these special organs were different por-
tions of the nervous mass of  the encephalon.
   Upon this hypothesis of the localization of the  various
functions of the encephalon is founded the phrenological
system of Dr.  Gall.
   He considers each of these functions to be the  appen-
dage of a determinate part of the brain or cerebellum, and
that the greater or less activity of each of them depends
in a great measure upon the development of the part
which is their  seat   Now in  man and most of the supe- 
INTELLECTUAL FACULTIES.
231
rior animals, the encephalon fills  the whole cavity of the
cranium, and the walls of this osseous case are in some
sort moulded  upon the nervous  mass, so  that  one may
judge of the proportional size  of the different parts of the
brain by the prominence of the corresponding parts of the
head.   And admitting these  suppositions  to be correct,
we may consequently judge  by mere inspection of the
cranium, of the inclinations and  faculties  of every indi-
vidual.
   Phrenologists admit that the feelings which give to ani-
mals their inclinations or excite their desires are situated
in the posterior and inferior parts of the encephalon ; the
instinct of propagation resides  therefore in the cerebellum;
the love of offspring would depend upon that part of the
third cerebral lobe which is seen immediately above this
organ;  the instinct which  renders  animals more  or less
social would result from the action of a neighboring part;
courage would depend upon that part of the brain situated
above and  behind the ear; the love of destruction on that
directly above the ears;  finally, the inclination  which in-
duces to the employment of stratagem and the  desire of
acquisition would occupy neighboring parts.   The feel-
ings on which depend the sentiments of  self-love, of van-
ity, circumspection,  benevolence, firmness, justice, etc.,
would have their seat in the superior and anterior parts of
the brain ;  lastly, the different intellectual  faculties  have
been assigned to the parts corresponding to the forehead.
   A great  argument in  favor  of  this hypothesis may be
drawn from the peculiarities to be observed in the config-
uration  of the heads of men, remarkable for certain quali-
ties of  mind, or the force of certain  inclinations, and the
variations observed in the form of the cranium of animals 
232
ANATOMY AND PHYSIOLOGY.
of the most opposite instincts.   What has  already been
said with regard to the facial line applies  especially to the
more or less  considerable  development  of the anterior
part of the brain, and the  existence of a  depressed and
retreating forehead  will give the whole head an aspect of
stupidity.   It  is also remarked, that in carnivorous ani-
mals  living by the  chace and  which display the  most
courage and ferocity, the  width of the  cranium, at  the
ears, is much greater than  in the  herbivorous, with mild
and timid manners.   It must also be allowed that in almost
all animals the posterior part of the head, where phrenolo-
gists place the love of offspring, seems  to  be more devel-
oped in females  than males, and we all  know that  the
tenderness of  a mother for her young is a much stronger
passion, than in the father.
  But if some of the suppositions which form the basis of
phrenology appear to be really quite plausible, others  are
not founded upon any conviction and must  even appear
absurd to all persons accustomed to analyze the phenom-
ena of intelligence.  Thus  some  phrenologists  admit a
particular faculty for the  appreciation of  weight, another
adapted to judge of length and so on.
  But we repeat, no fact is yet known suitable to prove
that this division  of labor  really exists  in  the  brain, and
some experiments of M. Flourens would even lead to the
idea that it does not.

                       MOTIONS.
  The various modifications of the faculty of  perception
which have been  noticed  in  the preceding pages, render
man and animals capable of knowing surrounding objects;
but their relations with the external world do not merely 
MOTIONS.
233
consist in these phenomena, in some sort passive.   These
beings may also act upon  foreign bodies, make changes
in them, move, and often  express in a manner, more or
less precise, their sentiments or ideas.
   This new series of functions, with which we contractility.
are now to be occupied, depends essentially upon a prop-
erty not less general among animals than  sensibility, to
wit, contractility.
   This name is given to that faculty possessed by certain
parts of the animal economy, of alternate contraction and
extension.
   In some animals of an extremely simple structure,  Muscles.
such as the hydrae, all parts of the body appear susceptible
of  this contraction ; and  however little we ascend in the
series of beings this  faculty soon becomes the property of
particular organs, called muscles.   These muscles, which
are  the active  instruments of  all our motions, form the
greater part of the mass of the body and constitute  what
is commonly called the meat, or flesh of animals.  Their
color is generally whitish.   In some  animals  they  are, on
the contrary, of a more or less intense red ; this color  does
not  necessarily belong  to  them, but simply  depends on
the blood they  contain.
   Each muscle is formed  by the  union of a certain num-
ber of muscular bundles, which are united by cellular tissue
and  composed of smaller bundles.   These  in their  turn
are formed of bundles less in volume, and, from division
to division, we finally arrive at fibres of an extreme tenuity,
which are straight, ranged  parallel-wise,  and  which,  seen
by a powerful microscope, appear to  be formed each  by  a
series of small globules of about one  three hundredth of a
millemetre in diameter.  After death  the muscular tissue is
                  30 
234
ANATOMY AND PHYSIOLOGY.
 soft and easily torn, but during life it is  very elastic  and
 resisting.  Finally, it is essentially composed  of a material
 already  met  with in  the blood  and  called  by chemists
fibrine.  We also find  albumen,  osmazome and some
 salts.
  co^ntmcuons.  Under the influence of certain exciting causes,
 the muscular fibres are contracted, and at the same time
 the bundles they form become larger and harder than in
 the state of relaxation.  Any one can  observe this phe-
 nomenon upon  himself, if  he executes any movement
 and observes the changes which take  place in the muscles
 called into action in producing it.  Let  any  one forcibly
 bend the fore-arm upon the arm, for example, the muscles
 of the anterior part of the arm will be found  swollen  and
 hardened.
    Fig. 44.1        _gy f-fog j^d 0f the microscope we  can
     -. a   i       easily distinguish  the manner in which
      \ x  i         _          o_
       b£       this contraction  is  made.    When  the
       til___c   muscular fibres  are in a state of  relaxa-
       Ill.........c   tion, they are extended in a straight line
       ■H       (fig. 44) ; but when  they contract, they
       a          suddenly take a zigzag course and pre-
 sent  many  angular and regularly opposite  undulations
 (fig. 45).  By repeating this experiment we are soon able
 to recognise that the flexions of each fibre take  place in
 certain determinate points, and never otherwise.   When
  1 Fig. 44.  Portion of a muscle, in the state of repose, seen by the micro-
scope to demonstrate the disposition of the fasciculi of muscular fibres and
the mode of distribution of the nervous filaments, — a, nerve; b b, fasciculi
of muscular fibres arranged parallel and in  a straight line; — c, nervous
filaments which separate  from the nerve a, and  traverse perpendicularly
the muscular fasciculi at equal distances. 
MOTIONS.
235
the contraction is feeble, these flexions are slightly marked,
and in the stronger contractions they never advance be-
yond angles of 50°.
   Thus by contraction the two extremities   Fig. 45.'
of  the fibre are  approximated without in
any respect changing its total length. Now,
these extremities  are fixed to  the parts the  c
muscles are to move, and by  the displace-  c
ment  of the former, the  latter  are drawn
with them.                                    i   'a
   This insertion of  the muscles into movable parts is not
made  directly, but takes place by means of an  interme-
diate  substance of a fibrous texture,  which  penetrates
into the substance of these organs, so as to  send a pro-
longation to each  of the fibres composing them.   Some-
times  this fibrous  tissue, which is white and pearly, takes
the form of a membrane and then it is called an aponeu-
rosis;  at  other  times it  resembles a cord  of varying
length and then constitutes what anatomists call  tendons.9
   We said above  that contractility  appertained  \"?eUnerCveesof
exclusively to the  muscular fibres :  these are actually the
only parts of the animal economy which possess the faculty
of contraction; but this property they owe to  the  ner-
vous system.
   Each muscular  bundle receives one  or several nerves.
These nerves, which are  surrounded  by a sheath called
neurilemma, are composed  of many  longitudinal filaments
and these  filaments  are scattered throughout  the whole

  1 The same muscle at the moment of contraction ; the letters a, b, c, in*
dicate the same parts as in the preceding figure.
  2 The tendons and ligaments are  vulgarly called the nerves, although
they have nothing in common.
 
236
ANATOMY AND PHYSIOLOGY.
muscle, passing nearly parallel between and transversely
upon the muscular fibres, precisely in  the points  corres-
ponding to  each  of the angles,  formed  by the zig-zag
folds, upon which contraction depends.   After  having
thus continued their course during a certain  time, these
nervous fibres are seen  to curve, bend, and return to the
brain, so that they appear to form with this organ a con-
tinuous circle.
  Now, if a nerve, which is thus distributed to the mus-
cles, be divided, and thus separated in a manner from the
central  mass of the nervous  system,  its fibres are pre-
vented from contraction ; they are  paralyzed.   It is suf-
ficient, merely to compress  the brain in a living animal,
to cause it to lose the faculty of  executing motions.
 experiments.   Many researches have been made to ascertain
the nature of  the influence  exercised by the nervous sys-
tem upon the muscles, when  it determines  their contrac-
tion.   The most celebrated are those of a physician of
Bologna,  Galvani; and at  the same time that they have
thrown new light upon this delicate question, they have
conducted to one of the greatest discoveries  of the past
century, that of galvanic electricity.
  The labors of  Galvani, Volta, and of  some other dis-
tinguished men, have demonstrated  that when  certain
bodies of different natures,  copper and iron, for example,
touch, they develope electricity, and this electricity passes
with  great rapidity through certain bodies, such as  the
nerves and the metals, which for this reason  are called
good  conductors  of electricity, while it is arrested by
others, such as glass and resin.
  When  a  muscle is paralyzed by the section  of the
nerve going to it, we  may, during some  time,  supply the 
MOTIONS.
237
 want of nervous action  by electricity ; and  by means of
 this agent cause contractions similar to those which, under
 ordinary circumstances, take place from the influence of
 the will.
   The most convenient manner of making these experi-
 ments is to deprive a frog of its skin, and divide the ani-
 mal on a level with the  loins, then  to seize the lumbar
 nerves  and envelop them in a small sheet of tin foil;
 then the abdominal members are to be placed upon a
 plate of copper, and every time that  the foil touches this
 latter metal, the muscles  are seen to contract, the legs
 bend and are agitated, and this half of the frog seems to
 be leaping, as when alive.  These singular effects may be
 produced sometime  after the death  of the  animal, and
 are also observed in man ; for by passing an electic cur-
 rent through the bodies of some criminals, they were
 thrown into violent convulsions.
   An analogous phenomenon takes place, when upon di-
 viding a nerve in a living animal, the portion adherent to
 the muscles is pinched or burned, the latter immediately
 contract, but yet this effect appears  to depend upon the
 same cause with the convulsions produced in the preceding
 experiments, for it has been proved that in all these cases
 there is a production of electricity.
   From the preceding statements  we learn that Theory  of
            x       °                        muscular con-
 the electric currents act upon the muscles in the traction-
 same manner  as  the  nervous influence, and the knowl-
 edge of this fact  has  led to a very plausible explanation
 of muscular contraction.
   Physics teach us that when an electric current traverses,
in a contrary direction, two parallel  branches  of a con-
ducting rod, an iron wire, for example, they will be found
to approach each  other. 
238
ANATOMY AND PHYSIOLOGY.
  We have also seen that the nervous fibres in their dis-
tribution to the muscles, form elbows.   It must  then be
supposed that the electric fluid, which has traversed them
in all the preceding experiments, follows the course  of
these curved fibres, and consequently descends by one
branch to ascend by the other parallel branch.   If this be
so, these nervous  fibres must be found in the same condi-
tion  with the  metallic conductor just  mentioned; they
must approximate, and by approximating, they must draw
with them and fold the muscular fibres  they traverse.
  Now,  the same phenomena may  be observed in the
muscular contractions  produced by means of the  nervous
influence, and  in those  caused by  electricity;  it may
therefore be supposed that in the two cases, the cause
which  produces them is, if not  the  same, at least very
analogous, and that in the normal state  these contractions
depend upon the  passage of a fluid having, in this respect,
the same properties with the electric  fluid.
  In this hypothesis, which is  due  to Messrs.  Prevost
and Dumas, the muscular fibres  would be  mere  passive
instruments in the phenomena of contraction, and these
nervous turns would be  the true motor agents.   A cir-
cumstance in  support of this opinion, which has been
established by many delicate experiments, is the constant
relation already mentioned between  the point in which
these nervous fibres  traverse  the muscular  fibres, and
that in which the latter  bend in  contraction ;  the nerves
are always found  at the  summit  of the angles formed by
these folds, and  this is  really  the  place  they should
occupy, if their approximation were  the cause of these
curves.
  However, we see that contraction can take place  only 
                      MOTIONS.                    239
in the muscular tissue, and that the action of the nervous
system is its determining cause.  Let  us now inquire
what are the parts taken  by the several  portions of this
system, in  the production of this important phenomenon.
   The muscles  present in themselves very great differ-
ences ; some contract only under the influence  of voli-
tion, others are  equally under the empire of this force,
but their contraction may also take place  independently
of it;  finally, there are  yet  others  on  the motions  of
which  volition  has no  influence.  The  muscles of the
limbs, etc., belong to the  former of  these three classes,
those of  the respiratory apparatus to the second, and the
heart, etc., to the third.
   All  those muscles  whose motions  can  be  Nerves of
                                               voluntary
caused   by volition  receive  nerves  from the  motion-
cerebro-spinal system.  But all the  nerves of this  sys-
tem  do not discharge these functions  ; some, as we have
already seen, belong exclusively to sensation.  The cere-
bral  nerves of the third, fourth, sixth, seventh, ninth, and
eleventh pairs,  (fig. 29)  appear, on  the contrary, to be
exclusively assigned  to  motion; finally,  the  cerebral
nerves of the  fifth  and tenth pairs,  and all the nerves
which  arise from the  spinal marrow,  discharge  these
functions at the same time that  they  serve for sensation.
Their anterior root, as already seen, gives them the fac-
ulty  of transmitting sensations to the  brain ; and by their
posterior the nervous influence  necessary for  voluntary
motion is propagated from the brain to the muscles.
   In fact,  when the posterior roots of the spinal nerves
are divided in the living animal, the parts to which they
are distributed are deprived of the power of contraction,
exactly as  if both roots had been divided. 
240
ANATOMY AND PHYSIOLOGY.
  Functions   When the spinal marrow is divided, the move-
 of the spinal             1
 marrow.  ments of all  the  parts  whose nerves originate
below the section are  suspended,  while  those  whose
nerves are yet in communication with the brain, continue
  Brain.   to be  moved.   But if instead  of thus  experi-
menting upon the spinal marrow, we act upon  the brain,
by removing or compressing it so as  to prevent the dis-
charge of its functions, all the muscles of voluntary mo-
tion are paralyzed at the same time.
 0ftboedies.ated   It would also appear that certain parts of the
nervous system exercise a different influence over  the
motions.  Thus M. Magendie has proved that if the por-
tion of the brain, called by anatomists the corpora striata,
be cut into, the animal thus mutilated is no longer master
of his movements, but seems driven  forward by some in-
ternal  force which he  cannot resist; he leaps forward,
runs with rapidity, and finally stops,  but seems unable to
cerebellum, move backward.   If, on  the  contrary, the two
sides of the cerebellum be wounded in one of  the mam-
miferae or in a bird,1 it will walk, swim, or even fly back-
ward, without being able to advance.
  When these lesions  are only practised  on  one side,
other phenomena will  be observed,  which  at  first sight
appear much more singular, but which are  consequences
of the effects already mentioned.  Thus, if one  side of
the cerebellum or of the annular protuberance be cut ver-
tically, the animal  begins at once to roll on its side, turn-
ing from  the  wounded part,  and sometimes w7ith such
rapidity, that it makes  more  than sixty revolutions in a
minute.

  ' From the experiments of M. Magendie it would appear that the same
effects were not observed in reptiles and fishes. 
                       MOTIONS.                    241

   From these curious experiments, and the  researches
upon the same subject by Flourens and some other physi-
ologists,  the  cerebellum and  neighboring parts of the
encephalon have been  found to  possess,  among other
properties, that of regulating the movements of locomo-
tion.
   The movements which,  although under the  Smenu.
direction of  the volition, are also independent of its  in-
fluence appear then to depend upon the action Functions of
         11              l       r               the medulla
of the medulla  oblongata.  In  fact, when the obloneata-
brain no longer discharges its  functions, and when con-
sequently there  can  be  no  volition, the muscles of the
respiratory apparatus continue to  act as if their move-
ments were  under the  direction of the will;  but when
this portion  of  the medulla is  destroyed, although the
brain be left intact, they are immediately arrested.
   Those muscles, whose contractions are entirely Inmouons.ry
independent of  the will, receive their  nerves from the
ganglionary system, and in this system resides their prin-
ciple of action ;  for if respiration be maintained by arti-
ficial means,  the whole encephalon may be destroyed, as
well as the spinal marrow, without arresting  the beating
of the heart, or the peristaltic motion of  the intestines.
   The contraction of the  muscular fibre  is  a  Lawsofmus-
                                              cular contrac-
phenomenon essentially intermittent. The mus- tion-
cles cannot remain in  a  state  of permanent contraction,
and at the end of a longer or shorter time they are neces-
sarily relaxed.   Thus the heart, whose action  only ceases
with life, alternately  contracts and reposes;  but in the
muscles of voluntary  motion,  these same  contractions,
interrupted by longer  or shorter intervals of repose, can-
not be continued beyond a certain time, for they produce
                   31 
242          ANATOMY AND PHYSIOLOGY.
a feeling of lassitude which increases till at last these
movements become impossible, which is only relieved by
a period of inaction or repose.
  The ease with which muscular fatigue  is manifested
varies greatly according to the individuals ; but, caeteris
paribus, it is in the ratio of the intensity of the contrac-
tions, the duration of each of them, and the rapidity with
which they succeed each other.
  The force displayed by the contraction of  a muscle
depends upon the texture of this organ ;  and the nervous
energy of the individual.   The large, firm, and red mus-
cles, are capable  of contracting  with more power than
the small, flabby, and  pale ;  but only when these condi-
tions are united to a very strong volition, can these organs
produce the greatest effects, and almost always they are
in an inverse ratio.   The  energy of the  muscular con-
tractions may be carried to an extraordinary degree by
the sole influence of the action of the brain.   We  ac-
knowledge the  power of an angry man and of  a lunatic;
and when, in the ordinary  state of the economy, a simi-
lar nervous energy is united to a great material develop-
ment of the muscular system, astonishing  effects result;
of such the ancients have transmitted us recitals in speak-
ing of their athletae, and the buffoons of our own day are
also sometimes examples.
   Muscular contraction is  an important  office  in several
of the functions, the  history of which has already been
given ; but the subject to  which we  shall now turn  our
attention  is more directly  connected  w7ith it, for we are
about to enter upon the study of the  general and partial
movements of  the body, upon which depend attitudes,
locomotion, and many other phenomena entirely mechan-
ical. 
MOTIONS.
243
   In the inferior animals the muscles are all in- Paofmeo3.ns
serted  into the tegumentarv membrane, which is soft and
flexible; and by acting  upon it they so modify the form
of the body as to impress on it motion entirely or in part;
but in  animals of a more perfect structure, the apparatus
of motion  is  more  complicated, and  is composed not
merely of muscles, but  also of a system of  solid pieces
which  serve to increase  the precision, force and extent of
the motions, at the same time that it determines the gen-
eral form of the body and protects the viscera  against
external violence.
   This solid frame, to which the muscles are at- skeleton.
tached, bears the name  of skeleton.  In certain animals,
such as insects and lobsters, it is situated externally, and
consists merely in a modification of  the skin ;  but in man
and all animals nearly allied (namely, the other  mammi-
ferae, birds, reptiles and  fishes,) it is situated in the inte-
rior of the  body, and is composed of  parts peculiar  to
itself.
   In some fishes (the rays, for instance,) the skel- cartilages.
eton is formed of a white substance, opaline, compact,  to
appearance homogeneous, very resistant and elastic, which
is called cartilage.   It is the same  with the skeleton  of
man and other animals  at the  early period of life; but
this state, which is permanent in the fishes spoken of,  is
in the  other animals but transitory, and  the cartilages  of
the skeleton become encrusted with stony materials of a
calcareous  nature, which render  them  stiff,  brittle, and
very hard, and which transform them to the state   Bone.
of bone.
   To  be  convinced that bones are but cartilages, har-
dened  by  the deposition of  calcareous  salts into  their 
244          ANATOMY AND PHYSIOLOGY.

substance, it is only necessary to macerate them for some
time in a particular liquid, called muriatic or hydrochloric
acid.   This liquid has the property of dissolving the stony
materials contained  in the bones without  attacking the
cartilages, so that the latter may  thus  be separated from
the salts which masked its  properties.1
  o/theT^e"!   The ossification of the  skeleton  commences
by an  infinity of  points which are constantly extending;
therefore the number of distinct osseous pieces is at first
immense;  but by  the  progress  of ossification  several
among them are  united, so that  in the adult there are
fewer  distinct bones than  in the infant; and  in extreme
old age, several bones are often united  in one, and parts
originally  cartilaginous  are  encrusted with  calcareous
matter.   The utility  of  this mode  of  development  can
be at once  comprehended ; in order that the  solid frame
of the body may not oppose its motions, the former must
always be composed of a great number of movable pieces,
but this division  is  especially  necessary when  all these
parts must  yield to the increase of the  organs situated in
its interior.
  StheCb^ees?f   The surface of the bones is always covered
by a membranous layer, to which is  given the name  of
periosteum, and their  substance is composed  of fibres  or
  1 From the analysis of M. Berzelius  the bones of the human skeleton,
completely deprived of fat, are composed to the hundred parts, as follows:
of cartilage, 32.17; vessels, 1.13; neutral phosphate of lime, with a small
portion of the fluoride of  calcium,  53.04; carbonate of lime, 11.30; phos-
phate of magnesia, 1.16 ;  soda, with a small proportion of chloride of  so-
dium, 1.20. In the bones of the ox this chemist found the same proportion
of animal matter, but less of the carbonate of lime.  The cartilaginous
part of the bones is composed of gelatine, and  is therefore used in the arts,
and in domestic economy, for the manufacture of glue and the preparation
of economical broths. 
MOTIONS.
245
lamellae, easily distinguished.   When these organs are to
occupy  a small space and present great solidity, as is the
case with the flat bones, which cover the majority of the
most important and delicate viscera, the osseous tissue is
extremely compact.   But when the bones are to occupy a
long space, the motions would be injured if their  weight
were considerable, their tissue is dense and close only upon
the surface, and in their interior exist large cellules or even
canals,  called medullary,  because  they  are filled with
marrow.
   The  bones vary greatly in form, and from this  Form.
variation they are  divided into  long, short and flat bones.
The former simply  present  a medullary cavity and are
always nearly cylindrical.   We often find in all of them
eminences which give attachment  to  the muscles or to
other parts, and which,  when they form a considerable
prominence, are  designated  as processes.  The bones
also present upon  their surface depressions more  or  less
shallow, and which serve to lodge the soft parts or to re-
ceive other bones which are  to move  in  these cavities,
and in  many places, are  holes which afford a passage to
the blood vessels or  nerves.
   The  name of articulation is given to the union Articulation.
of the various bones together.   The means of conjunction
employed by nature  for this purpose vary much, according
as  the  bones are  always to preserve the  same relation
and remain fixed, or to execute motions  of greater or
less extent.
   When the articulation of the bones is not destined to
permit  motion, it may take place in three ways : by jux-
taposition, by suture, or by implantation.   The articula-
tions by simple juxtaposition of the articular surfaces are 
246
ANATOMY AND PHYSIOLOGY.
only seen in certain parts of the skeleton, where the po-
sition of the bones is  such that they cannot be displaced.
In the articulations by suture,  the articulating surfaces
present  a  series  of  asperities and angular  projections,
which are  reciprocally received; thus these articulations
may have great solidity with but small extent of surface.
Finally  the  articulations  by  implantation  are  those, in
which a bone is set into a cavity  hollowed in the  sub-
stance of the bone which serves as  its base:  these are
the most solid but are rare.1
   In the movable articulations, the bones are not directly
united together, but are maintained in contact  by bonds
extending from one of these bones to the other.
   Sometimes these articulating surfaces are united by an
intervening cartilaginous or fibro-cartilaginous substance,
strongly adherent to both of them, and which only allows
them to  move by reason of its elasticity, (this is called the
articulation by continuity) :  at other times the articulating
surfaces  slide upon each other, and are only kept in  con-
tact by ligaments? which  surround the in and are so ar-
ranged as  to limit  their  motions.   The latter mode of
conjunction constitutes what  anatomists call  articulation
by contiguity, and is  met  with in all cases  of very ex-
tended motion.   The surfaces thus articulating are always
extremely smooth and surrounded by a cartilaginous layer,
which highly increases their polish ; but these are not the
only means employed  by nature to diminish the friction
in the joints : for she has placed in them a sort of raem-

  1 The teeth, which are not true bones, are the only parts thus articulated.
  2 The name of ligaments is given to collections of fibres similar to those
of the tendons, very resisting, round or flat, and of a pearly white,  which
fasten together the bones. 
MOTIONS.
247
branous pocket, called the synovial sac, which is similar
to the serous membranes,  and is filled  with a  viscid
liquid, which permits these surfaces to  slide readily upon
each other.
  All the muscles destined to produce the great Action of the
                            1                muscles upon
movements of the body, are  fixed  to the skele- thebones-
ton by  their two extremities.   Therefore,  by contrac-
tion, they must displace the  bone which presents to them
the most feeble  resistance, and  draw it towards the one
which remains immovable, and  which serves as  a fixed
point to move the former.  Now, in the majority of in-
stances, the  bones are  more movable as they are at  a
greater distance  from the central part of the body ; con-
sequently, the muscles  which are fixed to two of them
act in general upon  the  more distant, and  the  muscles
destined to move a bone always extend from this organ
to the trunk.  Thus the muscles serving to bend  the fin-
gers occupy  the  palm of the hand and  the fore-arm ;
those which bend the fore-arm  upon the arm occupy the
arm, and those which move  the arm upon the shoulder
occupy the shoulder.
  In certain  circumstances,  however, these muscles dis-
place the  bones  which in ordinary cases answer the pur-
pose of a  fixed point.   When we  attempt to raise  the
body  hanging by the hands, the  flexor muscles of the
fore-arm not being able to displace the latter, approxi-
mate the arm to  it, and thus draw up the whole body.
  The kind of movement caused by the contraction of  a
muscle generally depends on the one hand, upon the na-
ture of the articulation of the bone  displaced, and on the
other, upon the position of the muscle with regard to this
bone:  it always draws it to its  own side, and approxi- 
248
ANATOMY
AND PHYSIOLOGY.
 mates it to the point where its opposite extremity is fixed.
 Thus the muscles which flex  the fingers occupy  the  pal-
 mar face  of  the  hand and fore-arm, while those  for their
 extension are upon the opposite side of the limb.
   Several muscles are often so  arranged as to concur in
 the production of the same motion.   They are then said
 to be allied; and the antagonist of a muscle is the  one
 which causes the opposite motion.
   The muscles are also  designated, from their  uses, as
 flexors and extensors, adductors and abductors, rotators,
 etc.
 Fmcuscieslhe  The force with which a  muscle contracts depends
 upon its volume,  the energy of  the will, and some other
 circumstances already mentioned ; but the effect produced
 by this contraction depends, also in a great  measure, upon
 the manner in which it  is fixed  to the bone to be moved.
   Thus, all things being equal, the motion  caused by the
 contraction of a muscle will be  more powerful in propor-
 tion as the muscle is less obliquely inserted  upon the bone
 to be moved: when inserted  at a right angle its whole
 force  is employed in displacing the latter;  but in the  op-
 posite case, a more or less considerable part of its force is
 lost.
        Fig. 46.            Thus if the muscle  m,  the
               n    a    force  of  which  we  suppose
               M /      equal  to ten, is  fixed perpen-
   m      WwX-.....   dicularly to the bone /,  the ex-
      ^^\''f/\       tremity of  which a, is  movable
 g.....     y"U\          upon the fulcrum point r, it will
       d    b  l          only  have  to  overcome   the
weight of this bone, and will carry it from the position a b,
in the direction of the line a  c,  causing the point of its 
MOTIONS.
249
insertion to describe a space which we will also represent
by 10.  But if this muscle acted obliquely upon the bone,
in the direction of the line n b, for example, it would then
be quite different; for it will tend to carry it in the direc-
tion b n, and consequently to approximate it to the artic-
ular surface r, upon  which the extremity of the bone re-
poses, but the latter  being an inflexible stem this displace-
ment  cannot take place; the  bone can  only  turn upon
this point r, as on a  pivot, and the contraction of the mus-
cle n, without any loss of the  energy we have attributed
to it will only  be able to  carry this bone  in  the direction
a d, and consequently to produce a displacement for which
one fourth of  the force would  have been sufficient in its
first position perpendicular to the  bone.
  The muscles are inserted for the most part very oblique-
ly into  the  bones,  and  consequently in  a  manner very
little favorable to the intensity of the result  of their con-
traction.  There often exists, however, a disposition which
tends  to diminish   the  obliquity  of Fig.  47.  Fig. 48.
these insertions: this  is the swelling m j
met with at the extremities of most
of the long bones, and which princi-  i.....
pally serves to give  their  articulations
greater  solidity.  The tendons  (i),  of the  muscles  (m)
situated  above the  articulation are generally inserted di-
rectly below this swelling, and thus arrive at the movable
bone (o), by following a direction  more nearly approach-
ing the  perpendicular, as  any one  may convince  himself
by comparing the disposition of muscle  m in  figure  48,
where these swellings exist, with  figure 47, in which  the
articulating extremities have been represented without any
such swelling.
                    32 
250
ANATOMY AND PHYSIOLOGY.
   The distance separating the point of attachment of the
 muscle from the fixed  point on which the bone  moves,
 and from the opposite extremity of the lever represented
 by this organ, also exerts a very great influence upon the
 effects produced  by its contraction.   To explain this
 fact we must have recourse to Mechanics.
   Levers.   The bones  we  say represent levers, a name
 given  in physics to every inflexible rod which  moves
 upon a fixed point, called the fulcrum.  The force which
 puts the  lever  in motion is called the power, and  that
 which opposes  its displacement is  called the  resistance.
 The distance which separates the fulcrum point from the
 point to  which the  power or resistance is  applied,  is
 called the arm of the lever.
   The length of  the arm exerts a very  great influence
 upon the force  necessary to constitute  an equilibrium to
 a given resistance.  For proof let us observe the mecha-
 nism of the Roman balance, as it is  called.   The beam
            49-        is divided into two parts of un-
                       equal length by the fulcrum (a).
                  ^     At the extremity of one of the
                       branches (r), which is very short,
                       is found the resistance (or object
 to be weighed), and upon the other (p) slides  a weight,
 which makes the equilibrium to a resistance so much the
 more considerable as it is farther removed from the  ful-
crum and consequently the arm of the power of the lever
 lengthened,  that of the resistance remaining always the
same.
   Every  one knows too how great the  difference is  in
the power a man can employ when he seeks to raise any
burden with his arm  bent or  extended.  In  these  mo-
 
MOTIONS.
251
tions, the same muscles are  called into action, and the
lever-arm of the power remains the same, it is  only the
lever-arm of the resistance, represented by the  distance
from the shoulder to the hand, which is lengthened.
  The science of mechanics teaches us, that to consti-
tute an equilibrium  on  any lever whatever, the resistance
and the power must be proportional to the length of the
arms of the lever, that is, when multiplied by their re-
spective arms, they must both give the same product.
  Thus, to  make   an            pi~  50.
equilibrium to a resist-     r\       f\
ance  (r),  equal  to  10,     I  I       j  j
applied to the extremity   a^ &  [      c~\
of  a lever  (a  b) of the      v*ki       . 1        r
length 20,  the power                           ^P
(p), if applied at the same point and consequently at an
equal distance from the fulcrum (a), must  also be equal
to 10.   But if applied at the point c, to produce the same
effect, the power must be equal to 20,  for the resistance,
which we have supposed  equal to 10, being multiplied
by  the length  of its  arm of the lever (20), will give as a
product 200, and on the  other hand, the power arm  of
the lever (c a) being only equal to 10, the latter must be
multiplied by a force equal to 20, to give the same pro-
duct 200.   Finally, if  the power be placed yet nearer
the fulcrum, at the point d, it must have a force equal  to
100 ;  for its lever arm will be only 2, and 2 x 100 = 200.
  The disposition of the levers exerts as great influence
over the rapidity of the motions produced, as over  their
force ; and if, by employing a power comparatively feeble,
a much greater resistance can thus be overcome, a slower
or more rapid  movement may also be obtained with the 
252
ANATOMY AND PHYSIOLOGY.
aid of these instruments, by the employment of a motor
force of a certain rapidity.
                             Thus  let us  suppose  the
                          power p, to  act  upon  the
                          lever a r, so as to cause the
                          point of insertion c, to  de-
                          scribe a  space of  5 in  a
                          second, it will displace  at
                          the same time the extremity
r,  of the  lever and cause it to arrive at b, with a rapidity
equal to 25, for the distance described at equal periods
by this point will be five times as great as that described
by the point c.  The application, then, of a force whose
rapidity is only 5 to the point c, produces the same result
as if there  had been  directly applied to the point r, a
force whose rapidity is equal to 25.
   But from what has been already said we see, that what-
ever is gained in rapidity is lost in force, for such results
are obtained by making the resistance arm  of the lever
longer than that of the power.
   Now,  in  the animal  economy, nearly all the  levers
represented by the  bones  are  so arranged, as  thus  to
favor the rapidity of motion at  the expense  of the force
necessary to produce them.  Thus  when the extended
arm is brought down to the  side, if the rapidity with
which the muscles contract is such that  their  insertion
be displaced  three inches in a  second, the extremity of
the  limb  will be  removed, from its  primitive  position,
with the rapidity of  nearly three feet in a second.
   Having made these preliminary remarks upon animal
mechanics,  we  may now  undertake the study of  the
different parts of the apparatus of motion, which we shall
first examine in man. 
                       MOTIONS.                    253
   The  skeleton, as we have already said, is  skeleton.
composed of a great number of bones united  together;
it is divided like  the  body, into three parts, the head,
trunk and limbs.
   The most important part of the skeleton, which serves
for the support of all the others, and differs least in the
different animals, is the vertebral or spinal column.
   This name is given to a kind of osseous stem  extend-
ing the whole length  of the trunk, and  which is  com-
posed of a great many small bones called vertebrae, which
are placed one upon the other and solidly united together.
   This column (fig. 27), also called the  spine,   column*
occupies the median and posterior line  of the  Fig. 27.
body,  and  supports on its  anterior  extremity
the head, which may be considered as its con-
tinuation.   In man we reckon thirty-three ver-
tebrae, and they are divided into five  portions,
viz.:  a cervical portion composed of seven ver-
tebrae, a dorsal of  twelve, a lumbar  of five, a
sacral also of five, and a coccygeal of  four.  It
presents several curves and increases in size
from its  anterior or superior extremity to the
commencement of the sacral portion.   At  birth,  cd
all  the vertebras are perfectly distinct, and are simply
articulated with each other;  but in a short time  the five
sacral  are united  and  form but one bone, called the
sacrum (s).
   The essential character of  the vertebras is  jtvo.. 28
to be  traversed by a hole, which, by uniting
with those of the other vertebras, forms a canal,
extending from the cranium to the extremity
of the body, in which  the  spinal marrow is
 
254
ANATOMY  AND  PHYSIOLOGY.
Fig.  52. — Skeleton of  Man.
Frontal bone.    Parietal bone.
Scapula,
Temporal bone.
Dorsal f ertebra.
 
                       motions.                    255

lodged.   In  man the vertebras  of  the coccyx present no
such canal, for they are reduced to  a  rudimentary state
and merely  consist of so many  solid  nuclei.  On  the
sides, this vertebral canal communicates externally by  a
series of  holes, called holes of conjugation,  because they
result from the union of  two grooves in the superior and
inferior borders of each vertebra, so   as to  correspond
when these bones  are  united.  These  holes, as  already
shown, give  passage to different nerves which arise from
the spinal marrow,  and are distributed  to the several
parts of the body.
   Each vertebra is divided into a body and several pro-
cesses.    The body of the vertebra  (fig.  28, a,) is a thick
disc, situated in front of  the  vertebral  canal (or below,  if
the column is in a horizontal position, as in most animals),
and serving  to  give  solidity to the articulations of these
bones with each other.   The two faces of  this disc  are
nearly parallel, and each of them  is united to the corres-
ponding surface of the neighboring  vertebra, by a thick
layer of fibro-cartilage which adheres  to  each, over  the
whole  extent of the articulating surfaces, and only per-
mits them to be separated so far as its elasticity will allow.
The articulation of the vertebras is also strengthened  by
the existence of four small processes, situated on the sides
of the vertebral canal, and which  interlock with those of
the neighboring vertebrae.   Finally, behind  this canal*
there exists a process called spinous (b), which assists in
the same  purpose,  by limiting  the flexion of the column
backward; and fasciculi  of  aponeurotic  fibres extend,
also, from one bone to the other so as to fasten them to-
gether.
   The articulation  of the vertebras is thus rendered ex- 
256
anatomy  and physiology.
tremely solid, and the motions of each of these bones are
in general  very limited;  but the addition of these slight
motions  to  each  other,  gives sufficient flexibility to the
whole column  without  injuring its strength.   But  this
mobility  varies greatly in the different parts of the spine;
in the lower part  it is almost null, in the loins, on the con-
trary, it is quite marked,  but it is the greatest in the cer-
vical portion of the column;  therefore, in these parts, the
fibro-cartilaginous layer,  in order to allow of these move-
ments, is thicker  than in the back, and the spinous pro-
cesses are farther removed from  each other, so as to allow
of a  considerable curvature of  the  column before  they
meet.
   The weight of the body tends  constantly to curve the
vertebral column forward.  To resist this  flexion and
straighten the column, powerful muscles were  requisite,
which are inserted the whole length of its posterior face;
and to render their  action more powerful, nature  has so
arranged their point of attachment as  to allow them to
draw perpendicularly upon quite a long arm of a lever.
In fact, most of them  are fixed  to the extremity of the
processes called  spinous, which  form  a prominent crest
the whole length of  the spine, and others take their  ori-
gin from  two other processes (c), which are equally promi-
nent and are named  from  their  direction, transverse pro-
cesses.
   It must, also, be observed that in the portions of the
column where  these muscles  are to employ  the most
power, as in the  loins, these processes are much longer,
and consequently form a  lever far more powerful than in
the parts where  all  this  force is not necessary, as in the
neck, for example.   In animals  with a heavy head, situ- 
MOTIONS.
257
ated at the extremity of a long and horizontal neck, these
processes have  an extreme  length on  the back,  where
they serve for the attachment of the ligaments and mus-
cles intended to sustain these parts and support the neck.
   The motions of flexion of the column forwards require
scarcely any force, and the muscles employed  to produce
them, and situated in front  of the body of the vertebras,
are, consequently, small and few in number.
   The first vertebra of the neck, called the atlas, is much
more movable than any of the rest; it has the form of a
simple ring, and turns  upon a kind of pivot formed by a
process which ascends from the body of the next verte-
bra (or axis).   Upon this articulation are  effected nearly
all  the motions  of rotation of the head.  The  bonds
which unite these two vertebras  are far less strong than
those of  the other vertebras ; and in fact, in the  ordinary
position  of  the  body,  the weight of the head  pressing
upon  the atlas, tends rather to maintain them  in  contact
than to separate them.  When, however, the  head sup-
ports the entire weight of the body, as in those  who are
hung, the case is altered ; these two vertebras  then sepa-
rate easily, and their luxation produces almost instantane-
ous death in consequence of the compression of the spinal
marrow, precisely  at the  point whence originate the prin-
cipal  nerves of the  respiratory apparatus.   It was with
the view  of  causing this dislocation of  the neck, and, con-
sequently,  of abridging the sufferings of  criminals con-
demned  to  perish on  the gallows, that  hangmen were
formerly accustomed to rest one foot upon the shoulder of
the criminal at the moment he was thrust from  the ladder
with the cord  around his neck.  And from  the same
                   33 
258           anatomy and physiology.

cause, sudden  death may  happen  in  those imprudent
plays where a child is raised from the ground by the ears.
   The  vertebral column, as we have already said, sup-
ports in a measure all the other  parts of the body.  By
its superior extremity it articulates with the head, each  of
the dorsal vertebras articulates with a pair of ribs, and the
sacrum  is wedged between the two haunch bones.
  Head.    The head is composed of two principal portions,
the cranium and face.
 cranium.    The cranium is a kind of      Fig. 41."
osseous box, oval in form, occupy-    «   /
ing the whole superior and posterior   '\/^ i ~^\ / P
part of the head, and  lodging as    M^S^N   V-  *
before stated, the  brain  and cere- naZWpt^^Z'^j
bellum.    Eight bones are united to mcs "'^S{fW^r'^~~
form  the  walls, namely, the  frontal    S252T\ \  \\  °
or coronal in front (f), the two pa-   b   mij a%    c ta
rietal (p), above,  the two temporal  (t), upon the sides,
the occipital (o), behind, and the sphenoid (s), and ethmoid
below.   All these bones, with the exception of the last,
have  the form of large thin plates and are of a very com-
pact texture, and all articulated together so as to be com-
pletely immovable and to give the cranium great solidity.
These articulations are very remarkable in that they vary
in form in the different parts of the  cranium, for the pur-
pose  of better resisting external violence which  might
tend  to disunite these bones, and would produce different

  1/, Frontal bone,—p, parietal, — t, temporal, — o, occipital, — s, sphe-
noid,— n, nasal, — m s, superior maxillary,—/, malar or cheek bone,—
m i, inferior maxillary,— n a, anterior  opening of the nasal fossae, —  t a,
auditory foramen, — a z, zygomatic  arch formed by a part of the  temporal
and malar bones, —a, b, c, d, lines indicating the facial angle. 
MOTIONS.
259
effects, according to the point  on which it acts.  Thus
when a  blow falls upon the summit of the head, the
movement is propagated in  all directions,  and  tends to
separate  the parietal bones by driving forwards or back-
wards the frontal and occipital bones; therefore, all these
bones are united by closely serrated sutures.  But when
the cranium  receives a  blow upon  the  side, the effort
acting upon the  temporal tends to drive in this bone, to
prevent which accident, nature has united the temporal to
the neighboring  bones, not  by means of sutures, merely
adapted  to prevent disunion, but by a very oblique  articu-
lating border, so as to render this bone externally much
larger than the space in which it is set.
   The vault of  the cranium presents nothing remarkable;
but, at its base, we  find a number of holes which serve
for the passage  of the blood vessels of the brain  and of
the nerves, which arise from the encephalon.  Through
one of these holes,  hollowed in the occipital bone  and
much larger  than the others, passes  the spinal marrow,
and there exists  near its border upon  each side, a large
convex process called  the condyle,  which serves for the
articulation of the head upon the vertebral column.  The
head  is  nearly in equilibrio upon this kind of pivot, but
yet the portion in front of the articulation  is more volu-
minous than that behind, and tends to counterbalance the
first.  Therefore,  the muscles  which extend from the
vertebral column to  the posterior part of the head,  and
which serve to raise the latter, are much  more numerous
and powerful than the flexor muscles, placed in the same
manner in front of the column; and when the former are
relaxed,  as happens  during sleep, the head  usually leans
forward and rests upon the chest. 
260
ANATOMY AND PHYSIOLOGY.
   Upon the sides  of  the  base of the cranium, we also
observe  two  very  large  processes, called  mastoid,  into
which are inserted  two muscles, which descend obliquely
to the chest at the  anterior part of the neck, and serve to
turn the head  upon the vertebral  column.1   Finally, di-
rectly in front  of these processes, is the opening of the
external auditory duct, which, together with the several
parts of the middle and internal ear, is hollowed into that
portion of the temporal bone called, from its hardness, the
petrous.
   Face.    The face is formed  by the union of fourteen
bones of very different forms, and presents five great
cavities for lodging  the organs of sight, smell and taste.
All these bones, except  the lower jaw, are completely
immovable,  and are articulated together or with  the bones
of the cranium.  The two principal are the superior max-
illary bones  (ms), which constitute  almost  the  whole of
the upper jaw, and which articulate with  the  frontal so
as to aid in  the formation  of the orbits and nasal  fossae.
On  the outer side they are articulated with  the malar
bones (j),  and behind  with the palate bones, which in
their turn are joined to the sphenoid.
   The orbits, as we have elsewhere seen, are two conical
fossae or pits, the base of  which is directed  forward : the
arch of these cavities is formed by a portion of the frontal
bone and their floor  by  the  superior  maxillary bones.
On the inner side,  the ethmoid and a small bone, called
the  lachrymal, complete  their walls, and on  the  outer,
they are formed by the malar and the sphenoid ; the latter
also occupies the bottom  of  the orbit, and in it are found
1 Called, from their attachment, sterno-mastoid muscles. 
MOTIONS.
261
the openings for the passage of the optic nerve, and the
other nervous branches of the apparatus of vision.   In
the vault of the orbit  may be  seen a depression  which
lodges the lachrymal gland, and on  its exterior wall is
found  a  canal which  descends vertically into the nasal
fossae and gives passage to the tears.
   The nose is formed in a great measure  of cartilage;
thus in the  skeleton  the anterior  opening  of the nasal
fossae (na) is very large, and the bony portion formed by
two small bones,  called nasal (n), is  but slightly  promi-
nent.  The nasal fossae are very extensive;  superiorly,
they are excavated in the ethmoid bone, the whole interior
of which is filled with  cellules; inferiorly, they are sepa-
rated from the mouth by the arch of  the palate, which is
formed  by the superior maxillary and two palate bones;
finally, they are separated at the median line by a vertical
septum formed superiorly by a  plate of the ethmoid, and
inferiorly by a  particular bone  called the vomer.  In the
interior of  these  fossae  may, also,  be found two distinct
bones which are called the inferior turbinated  and also
the opening  of  the frontal,  sphenoidal, and  maxillary
sinuses, cavities more  or  less extensive, hollowed in the
bones from which they take their names.
   All the teeth of the  upper jaw are implanted into the
superior maxillary bone.   In early life it is formed of sev-
eral pieces, and in most animals we find an anterior por-
tion which is called the intermaxillary bone.
   The lower jaw, in man, is composed of a single bone,
for the two halves of which it is formed in many animals
are  early  united and completely consolidated.   This
bone, called inferior maxillary, much resembles a horse-
shoe, the curved ends  of which are greatly raised.   It is 
262
ANATOMY AND PHYSIOLOGY.
articulated with the temporal bones by a projecting con-
dyle situated on each extremity, and received in a cavity
called the glenoid (e) ; finally in front  of these condyles
there rises upon either side a process called  corono'id,
which serves for the insertion of one of the levator mus-
cles of the lower jaw (the temporal muscle) ; these mus-
cles (t) are all  fixed  to the angle of the jaw, and at a
short distance from  the fulcrum point on which  this lever
moves.   In  the majority  of instances, on  the  contrary,
the resistance to be overcome by this  same lever during
mastication, is applied to  the anterior part  of the jaws ;
therefore, these muscles, although very powerful, can pro-
duce but very  feeble effects, and  to crush between the
teeth the hardest bodies,  they must be carried as far as
    Fig. 22.     possible to  the bottom of the mouth, so
                as  to shorten the resistance arm of the
                lever and render it equal or even shorter
                than that of the power.  These muscles
                are fixed on the internal, as well as ex-
                ternal face, of the jaw, and  make their
fulcrum point upon  the sides of the head, as  high as the
temples,  passing between  the lateral walls of the cranium
and a bony arch called the zygomatic (z), which extends
from the malar bone to  the  ear, and also serves for the
insertion of these organs.
   The head, as before shown, is essentially composed of
twenty-two bones ;  but their number is actually greater;
for in the interior of each temporal  bone,  there are, as
elsewhere stated, four little bones belonging to the appa-
ratus of hearing, and the  hyoid bone may also be consid-
ered a dependence  of the head.   This bone is suspended
from the temporal bones by ligaments and is placed across
 
MOTIONS.                   263
the upper part of the neck, where it bears  the  tongue
and sustains the larynx.
   The cervical vertebras only articulate with each Thorax.
other,  or with the head and the first dorsal vertebra; but
each of the  twelve  dorsal  vertebrae supports a  pair  of
very long and flat arches  which curve around the trunk,
so as  to form a kind  of osseous  cage to lodge the heart
and lungs.   These arches are the  ribs,  the num-  Ribs.
ber of which is  consequently twelve on  each side of the
body; their  posterior extremity is articulated with  the
body of the  corresponding  vertebra  and with one of the
transverse  processes; the other extremity is continuous
with a cartilaginous shaft, which, in certain animals (birds,
for example,) is always  ossified, and is then called the
sternal rib.   The cartilages of  the seven first pairs of ribs,
which  are called the true ribs, are united to the sternum,
which  is a single  bone, occupying,  in front, the  median
line of the body and  serving to complete the walls of the
thoracic cavity; the  five last  pairs of ribs do not reach
the sternum, but are joined to the cartilages of the pre-
ceding ribs, these are called the false ribs, (fig. 17).
   Upon the  bony cage just mentioned are fixed   SSM
the superior limbs.  In each of them may be distinguished
a basilar portion, which may be compared to a pedestal
upon which is inserted the essentially movable portion  of
the limb,  which itself represents a lever, to which  the
former serves as a fulcrum.   This basilar portion is com-
posed  of two bones,  the scapula and clavicle.
   The scapula is a large flat bone, occupying the  sCaPuia.
superior and external part of the back:  its form is nearly
triangular, and it presents, on  the upper  and outer  side,
an articulating cavity quite large, but rather shallow, which 
264
ANATOMY AND PHYSIOLOGY.
receives the extremity of the bone of the arm (glenoidal
fossa of the scapula).  At its superior border we find a
projecting process called the coracoid, and on its external
face a very prominent horizontal  crest, which terminates
above the articulation of the shoulder by  a process called
the acromion, at  the  extremity  of which  the  clavicle  is
  ciavicie. articulated.  This latter bone is small and cylin-
drical ; it is placed across the superior part of the chest
and extends, like an arch, from the sternum to the scap-
ula.   Its principal use is to keep the shoulders separated:
and, therefore, it is very often broken, when, by falls upon
the side, this part is driven with violence toward the ster-
num ; and  in those animals  which bring the  arm  power-
fully to the breast (as birds in flight), this bone is greatly
developed, while it is  completely wanting in those who do
not execute such motions, and only move their limbs  lon-
gitudinally, as in horses,  etc.
 thertolTide?  Numerous muscles fix the scapula to the  ribs.
One of the principal is the serratus magnus, which extends
from the anterior part of the thorax to the  posterior border
of this bone, passing between it and  the  ribs.   In man it
is not much developed ; but in quadrupeds it is extremely
strong and  constitutes with  that  of  the opposite side a
kind of girth, which supports the entire weight of the trunk,
and which  prevents the  scapulas from ascending toward
the vertebral column.   In man, the trapezius muscle, which
extends from the cervical portion of the vertebral column
to the scapula, has, likewise, very  important functions: for
it raises the shoulder and sustains the weight of the entire
thoracic extremity, therefore it is greatly developed.
   The portion of the  thoracic extremity which constitutes
the lever to which the scapula  serves as a  fulcrum, is
composed of the arm, fore-arm, and hand. 
MOTIONS
265
   The arm is formed by a single long cylindrical  Humerus.
bone  called the  humerus.    Its superior extremity (or
head)  is  large, round, and  articulated with the glenoid
cavity of the scapula, in which it can roll in any direction.
The muscles which move this bone  are inserted into its
superior third and attached  by their  opposite extremity to
the scapula or  thorax.  The three principal are the great
pectoral, which carries the arm inward at  the same time
it depresses it; the great dorsal, which carries it backward
and downward, and the deltoid, which raises it.
   The inferior extremity of the humerus  is enlarged  and
has the form of a pulley, upon which the fore-arm moves
as on a hinge.
   Two long bones, placed parallel, form this por- TTJ"diu"d
tion of the thoracic extremity; the ulna situated  on  the
inner,  and the  radius on the outer side.  They are united
by ligaments and an aponeurotic septum, which extends
from one to the other, their  whole length:  but yet they
are movable, and the radius, which bears at its extremity
the hand, can  turn upon the  ulna, which  serves for its
support.   From the different uses of these  two bones it
might  be foreseen what would be the principal differences
in their general form.   The  ulna, to articulate  in a solid
manner with the humerus,  must present at its superior
extremity a certain size, and an extensive articulating sur-
face, while at its inferior extremity, where it  serves as a
pivot to the radius, it  must be small  and rounded.   The
radius  on the contrary must  be, for the same reason, small
at its superior,  and very large at its  inferior extremity, to
which  the hand is suspended.  This is actually the case,
and we also observe that these two  bones  only touch at
                   34 
266
ANATOMY AND PHYSIOLOGY.
their two extremities, which renders more easy the mo-
tions of rotation of the radius upon the ulna.
   The ulna which carries with it the radius, moves upon
the radius in only one direction; it only executes motions
of flexion and extension, and in the latter it  can only
form, with the humerus, a straight line, for it presents be-
yond its articulating  surface a process, called  the olecra-
non, which in that situation rests  upon the humerus and
affords  an  invincible obstacle  to any farther extension.
The extensor and flexor muscles of the fore-arm  extend
from the shoulder, or superior part of the humerus, to the
superior part of the ulna:  wherefore they are arranged in
a manner favorable to the  rapidity of motion of  the fore-
arm, but very unfavorable to  the  employment of a great
force ;  for the power-arm of the lever, represented by the
space comprised between  the  articulation of the  elbow
and their insertion, is very short, w7hile the resistance-arm
of the lever, which is equivalent to the entire length of the
limb from this same articulation, is, on  the contrary, very
great.
   The rotation of the radius and of the  hand upon  the
ulna are effected by muscles situated on the fore-arm, and
which extend obliquely from  the extremity of  the hume-
rus, or ulna, to one or other of these parts.
  Hand.    The hand  is divided into three portions, carpus,
metacarpus, and fingers.
  carpus.   The carpus or wrist is formed by two  ranges of
little short bones, united very closely together, so that the
whole of this part enjoys a degree of mobility ;  although
each of the bones composing it can  scarcely be displaced,
an arrangement which is adapted to  give their articula-
tions a very great solidity.   They are in number eight. 
MOTIONS.
267
Four of these bones, viz.:  the scaphoid, semi-lunar, pyri-
midal  and pisiform  compose  the  first range; the  four
others, which are called trapezium, trapezoid, os magnum,
and os unciforme, form the second.  It must be remarked
that  these different bones are arranged so  as to  protect
the vessels and nerves passing from the fore-arm to the
hand ; for  this purpose  they  form,  with  the ligaments,
a canal which  is traversed by these organs and  which
can support, without flattening, the strongest pressure.
  The metacarpus is composed of a range of little Metacarpus.
long bones, placed parallel-wise, and equal in number to the
fingers with which their  extremities  articulate.   Four  of
these bones are united by their two ends, and are scarcely
movable; but the fifth, which bears the thumb, only artic-
ulates  with the carpus and moves freely upon the latter.
  Finally, the fingers are formed each by a series  Phalanges.
of small, slender bones, joined end  to end, and called
phalanges.  The thumb presents only two, but the fingers
have three.  The last phalanx bears the nail.  The fingers
are all very movable  and may all  move independently  of
each other.  Their  flexor and extensor muscles form the
greater part of  the fleshy mass of the fore-arm, and termi-
nate by extremely long and small tendons, some of which
are fixed to the first  phalanges, and others to the last.
  When we examine  the united thoracic extremities, we re-
mark that the several  levers joined end to end to form them,
diminish progressively in length.  The arm, for instance,
is longer than the fore-arm ; the latter is longer than the
wrist, and each phalanx is shorter than  the preceding.
The utility of this arrangement is readily comprehended.
The  numerous  and close articulations at the extremity  of
the limb," permit the latter to vary its form in a thousand 
268
ANATOMY AND PHYSIOLOGY.
ways, and to accommodate itself to the body to be seized ;
while the long  levers, formed  by the arm  and  fore-arm,
permit us to carry the hand rapidly to  considerable dis-
tances.   The motions of the humerus upon the scapula
principally determine the general  direction  of  the  limb ;
the articulation of the elbowr is specially designed to per-
mit it to  be lengthened or shortened.
 membeTs.    The structure of the inferior  members is very
analogous to that of the thoracic, and the principal differ-
ences are those necessary for their greater  solidity at the
expense  of their mobility, and to render them  organs of
locomotion rather than of prehension.  They also have  a
basilar portion, which is the counterpart of  the  shoulder,
and is called the  haunch, and an articulated lever formed
of three  parts, the  thigh, the leg  and the foot, which
answer to the arm, fore-arm and hand.
 «iac bone.   The haunch, or basilar portion of the abdominal
extremity, is formed by a large flat bone, called  the iliac
(from the latin word ilia, flank)  or coxal bone  (from the
word coxa, which in  Greek signifies haunch).  This bone
results from the union of  three principal  pieces, always
distinct in foetal life,  which  may be compared to the body
of the scapula, its coracoid process and  the clavicle.  The
iliac bones have not  bases corresponding to  the  bones of
the shoulder, ribs and sternum, to rest upon ; being des-
tined to sustain the entire weight of the body they must,
however, be fixed in the most solid manner to the trunk ;
thus they are articulated  behind with the portion of the
vertebral  column, called the sacrum, and   in front they
unite and form an arch, called the pubis.  They are per-
fectly immovable, and from the union of these two  bones
and the  sacrum  results  a  large  osseous cincture,  which 
MOTIONS.
269
inferiorly terminates the abdomen, and  which,  from its
open form, is called pelvis (fig. 52).  This kind of ring is
closed  inferiorly by muscles and gives passage to the in-
testine called  rectum, and to the genito-urinary organs.
Upon the sides, externally, we observe upon each iliac bone
an articulating cavity, nearly hemispherical, which  serves
to lodge the  head of the  thigh bone.   Finally, most  of
the muscles which move the  thigh and leg, are inserted
into the pelvis, and the muscles, which enclose,  as  we
have elsewhere seen, the abdominal cavity, are fixed  to
it, and  reach  from  it to the thorax.
   The thigh,  as the arm, is composed of a single  Femur.
bone, which is called the femur.   Its  superior extremity
is inclined inwards, and its  head, which  is rounded, is
separated  from the body of the bone by  a  contraction,
called the neck of the femur.  At the lower end  of this
neck, and  at  the  point where it joins  the body  of the
bone  at  an  open  angle,  are  several  large  tuberosities
which  may be felt through the flesh, and which give in-
sertion  to  the principal motor  muscles of the  thigh;
finally, its  inferior extremity is very large and  presents
two condyles  laterally, compressed and rounded from be-
fore backward, which slide upon the articulating  face of
the principal bone of the  leg and only permit the latter
to be bent, or extended, while the  femur  itself may move
upon the pelvis in any direction.
   The difference of the leg and fore-arm is much 1."%?^?'
greater.  Besides  the fibula and tibia, which are the two
principal bones of which this  part of the  limb is com-
posed,  as the fore-arm of the ulna and radius, we  find in
front of the knee  a third bone called the patella, which
may be regarded as analogous to the olecranon process of 
270
ANATOMY AND PHYSIOLOGY.
the ulna, and which  principally serves to elongate from
the knee the tendon  of the extensor muscles of the leg,
and to render its insertion more oblique, an arrangement,
which as already shown, must  increase the power of its
action.   The foot not being required to execute motions
of rotation as  the  hand, but  requiring,  to support the
whole weight of the body, that it  should present great
solidity in  its articulation, the two  bones of the leg do
not move upon each other, and the one which articulates
with the femur and which represents the  ulna (the tibia),
is also the  one to the extremity of which the  foot is at-
tached.  The fibula, which is small and  situated on the
external side of the  tibia,  only serves, so to speak, to
maintain the foot in its natural position and to prevent it
from  turning inward.   Its  superior extremity is applied
against the head of the tibia, and its inferior constitutes
the outer ancle.
  Foot.    The foot is composed, as  well  as the  hand, of
three principal parts, namely, the tarsus, metatarsus, and
the toes.
 Tarsus.   There are seven bones in the tarsus, and it only
articulates with the leg by one of them, the- astragalus,
which ascends above the others and presents  a  head in
form of a pulley, adapted to the cavity  formed  by the
articulating surface  of the  tibia and the two malleoli.1
The astragalus rests upon the calcaneum which  is pro-
longed farther behind and constitutes the heel ; lastly a
third bone, called scaphoid, terminates the first  range of
the bones  of the tarsus, and the second  range  is com-
posed like the hand, of four small bones, three of which

 1 The inner malleolus, or ancle, is a process of the  tibia; the outer is
formed by the fibula. 
MOTIONS.
271
have  received  the  name of  cuneiform  bones,  and  the
fourth, placed in front, is called the cuboid.
  The bones of the  metatarsus, to the number Metatarsus.
of five, exactly resemble those of the  metacarpus:  only
they are  stronger and less  movable, especially the inner,
which is  arranged in the same manner as the rest. Phalanges.
It is the  same with the  toes ;  we reckon the  same num-
ber of phalanges as in the  fingers of the hand,  but they
are shorter and not so  easily moved.   The great  toe is
not detached  from  the others  and cannot  be  opposed to
them, as the thumb to the  other fingers.
  Upon  the  internal  side  of  the foot, the  bones  of the
tarsus and metatarsus form a  kind  of arch  to lodge and
protect the nerves  and  vessels, which  descend  from the
leg to the  toes.   When this arrangement does not exist,
and the  sole  of the foot is flat, as sometimes  happens,
these nerves are compressed by the weight of the body,
and  walking cannot be long continued without pain.
The  whole extent of the  foot, however, rests MtheClfeSg.°f
upon the ground,  and  forms a large  and  solid base of
support;  it can be  moved upon the leg only in the direc-
tion of its length, and  the muscles serving for this pur-
pose surround the tibia  and fibula.   The extensors of the
foot, which form the calf of the leg, are fixed to the cal-
caneum by a long tendon,  called the tendon of Achilles,
and are arranged in the manner most favorable to their
action ; for their insertion  is nearly at a right angle and
farther removed from the fulcrum than the  resistance to
be overcome,  when the weight of the  body, pressing up-
on the astragalus, is raised  by the foot.
  All the mammiferae, birds, reptiles, and fishes,  Animals with
                             1              'an   internal
have an  internal skeleton, more  or less nearlj
       i
keleton. 
272
ANATOMY AND PHYSIOLOGY.
resembling that of man, composed of nearly the same
bones, and likewise moved by muscles placed between
this solid  frame and  the tegumentary  envelope.   This
skeleton gives to their  body its general form, and upon
its disposition and the action of the muscles  fixed to its
various parts, depend the attitudes as well as  motions of
these  animals.
 standing.    A small number  of these beings lie with the
whole length of their bodies  upon the ground, and only
move  by undulations of the trunk; but others are ordi-
narily sustained upon their  limbs, and the  name of stand-
ing is given to the state in  which an animal thus supports
itself  on the  ground by its  legs.
  That the limbs may remain firm and thus sustain the
body, their extensor muscles must be kept  in a state of
contraction,  for,  without it, these organs would bend
under the weight they support and thus occasion  its fall.
We have already seen that the  muscles are more quickly
fatigued the  longer each contraction  continues;  thus in
most  animals, standing for  a long time is  more fatiguing
than  walking,  in  which latter case,  the extensor and
flexor muscles mutually relieve each other.
  This condition  is not the only one  indispensable  to
standing ; that the body may remain upright on the limbs
thus stiffened, it must be in equilibrium.
  An equilibrium  is established, not  only when a heavy
body  rests upon a resisting object with the whole extent
of its largest surface ;  but  also, when it is so placed, that
if one part of the mass be depressed  toward the earth,
an opposite part, equally heavy, would be raised in the
same  degree ;  the weight of one part  serves then to
counterbalance that of  the other, and the point  around 
MOTIONS.
273
which all these parts are  reciprocally in equilibrium and
where support must be given to keep in place the entire
mass, is called the  centre of gravity.   To support this
centre, it is requisite that the base of support (that  is to
say, the space occupied by the points by which the mass
leans upon a resisting object, or that comprised between
these points), be  situated vertically beneath it.
   That the body of an animal  may remain in equilibrium
upon its paws,  the vertical line passing through its centre
of gravity must consequently fall within the limits of the
space left between  the feet,  or covered by them : and
the larger this base of support is in relation to the height
at which  the centre of gravity is found, the more stable
will be  the equilibrium, for the more it may  be displaced
without  throwing the  line of gravity, just  mentioned,
beyond the limits of this base.   It is also  deserving of
note, that the more difficult the equilibrium to  be  pre-
served,  the more  intense must be the  muscular contrac-
tion to maintain it, and the more fatiguing the position of
the animal.
   From this reasoning it might be inferred, that when an
animal  rests upon all-fours, its  standing  will  be more
firm, solid, and less fatiguing than when it only rests
upon two, and  that in this latter case, its equilibrium will
be more stable  than  when it only  rests upon one  leg :
for the  extent  of the base of  support  is thus constantly
narrowed.  When an animal is supported upon four legs,
the space comprised between  them  is very considerable,
and can be but slightly modified  by the larger or smaller
extent  of the surface  of  these  organs.   To  render
them very large would then have increased their weight,
without adding to the solidity of the base of support:
                   35 
274
ANATOMY AND PHYSIOLOGY.
                     therefore, in most quadrupeds, the
                     members touch the ground only
                     by an extremity, hardly  dilated;
                     and we find the number of fingers
                     constantly  diminishing,  without
                     injury to these organs as instru-
                     ments of locomotion :  the foot of
                     the stag  and  horse are cases in
                     point (fig. 53  and 54); but when
                     the animal only rests upon two of
                     its feet,  whatever  be  their  dis-
                     tance  apart,  the base of support
                     can have no  solidity from  before
backwards, only in as much as these organs touch the
ground in a considerable extent, as in the foot of man ;
and  when an  animal readily  supports itself upon  one
paw, as birds,  nature must have given their  feet more
width, as  well as length.
  To allow an animal to put itself in equilibrium upon
a single leg,  the  foot on which it  rests must also  be
placed vertically below the centre of  gravity of its body,
and its muscles so arranged  as to permit  it to  keep this
limb inflexible and immovable.  Man  can  do this ;  for
the centre of  gravity of his  body is about the centre of
his  pelvis, and when placed in a vertical position it  is
enough for him to lean a little to the side not supporting
the weight, in order that the  line  of gravity may fall
upon the sole of the foot of the opposite  side ; but with
most quadrupeds the thing is impossible.
  Most of these latter animals cannot even remain erect
upon their hind paws, on account of  the direction of the
members relatively to the trunk; and if they do succeed 
MOTIONS.
275
for an instant, it is impossible for them to remain so, be-
cause their base of support is very narrow, the centre of
gravity of their body is placed very high (toward the chest),
and the muscles called  into action  in this attitude must
be contracted with a violence requiring immediate repose
In man and  a  small number  of other  mammiferas, the
vertical position upon the two abdominal limbs, is, on the
other hand, more  or  less easy; for these  members may
readily be placed  in the direction of the axis of the body,
the centre of gravity is situated very  low, and the  base
of support formed by  the feet  is very large.   In  man
especially, is this  attitude rendered solid by  the width of
the pelvis, the form of  the feet, and several other corres-
responding peculiarities of organization.
   In the vertical  position, the muscles  of  the posterior
part of the neck are contracted to keep the head  in equi-
librium upon the vertebral column,  the extensor  muscles
of which are also  called into action, to prevent it  from
yielding under the weight of the thoracic members and of
the viscera of the  trunk, which tend to curve it forward.
The whole weight of the body is thus transmitted by the
vertebral column to the pelvis, and from the pelvis to the
femur.  Left to themselves, these latter bones would bend
upon the pelvis,  and the trunk would fall forward, did not
the contraction of  their  extensor muscles keep  them  ex-
tended.  The extensor muscles of  the  leg, at  the  same
time, prevent the knees from bending,  and  the extensors
of the foot keep the leg in a vertical position, so that  the
weight of the body is transmitted from the  thigh to  the
leg, from the leg to the foot and from  the  foot to  the
ground.
   The seated position is less fatiguing than standing,  be- 
276           ANATOMY AND PHYSIOLOGY.

cause the weight of the  body being then  directly trans-
mitted from the pelvis  to  the base of support, it is not
necessary for the extensors of the abdominal extremities
to contract in order to maintain the equilibrium.  Finally,
when man is laid upon  his back or belly, the weight of
each movable portion of his body  is directly transmitted
to the ground, and  consequently, to continue so, he is not
required to contract a single muscle.
 Locomotion.    The progressive motions by which man  and
animals are transported from one place to another, require
a determinate rapidity in  a certain direction  to  be  im-
pressed upon the centre of gravity of their bodies.  This
impulse is  given to it by  the employment of a  certain
number  of articulations, more or less bent, and the posi-
tion of which is such that upon the side of the centre of
gravity  their employment  is free, while in the opposite
direction it  is confined,  or even  impossible, so that the
totality  or greatest  part of the motion produced, takes
place in the first of these   directions.  The  same thing
then takes place, as in a spring with two branches, one
extremity of which  is applied against a  resisting obstacle,
and the two branches of which, after being approximated
by a force from without,  are restored to their former lib-
erty ; by  reason of their  elasticity they would tend to
separate equally, until restored to their  position  before
they were approximated;  but that applied  against the
obstacle, not being  able to overcome  it,  the  movement
will take place  in an entirely opposite  direction, and the
centre of gravity of the  spring will be repelled from this
obstacle with a greater or less degree of rapidity.   In the
body of animals, the flexor muscles of the part employed
in each kind of  motion, represent  the force which com- 
MOTIONS.
277
presses the spring, the extensors  represent the  elasticity
which  tends to separate the branches, and the resistance
of the ground, or fluid in which these beings move, repre-
sents the obstacle which opposes the extension of one of
the branches.
   Walking is a motion upon a fixed plane,  in  Progression.
which  the centre of gravity is  alternately moved by one
part of the locomotory organs, and sustained by the others,
without entirely preventing  at any time  the  body from
resting upon the ground.   This latter circumstance dis-
tinguishes it from leaping and running, motions in which
the body quits momentarily the ground, and throws itself
into the air.
   In walking upon  two feet, in man and the other animals
to whom this mode of locomotion is possible,  one of  the
feet is  carried  in front, while the other is extended  upon
the leg;  and as this latter  leans upon a resisting plane,
its elongation displaces the pelvis and projects the whole
body forward; the  pelvis turns at  the same  time  upon
the femur of the opposite side which sustains it, and  the
leg, which previously remained behind, is bent  and car-
ried in front of the other, then straightens, and in its turn
serves  to sustain the body while the other limb, during
its extension, gives a new impulse to the centre of gravity.
By these alternate motions of extension and flexion, each
limb bears,  in its  turn, the weight  of the body,  as  in
standing upon one foot, and  at every step the centre  of
gravity is pushed forward; but  we see that it must, at the
same time, be carried alternately to the right  and to  the
left, to be directly above each of its bases  of support.
   The majority of quadrupeds in walking  make use prin-
cipally  of their hind legs to propel  their  bodies  forward, 
278
ANATOMY AND PHYSIOLOGY.
and of their anterior legs to sustain themselves in the new
position given by each  step.  Wrhen these  motions  are
made by all four feet at the  same time, the animal is  for
an instant suspended above the ground, and this mode of
locomotion constitutes  the  gallop.   In walking, two feet
only contribute to the formation of each step, one in front,
the other behind;  in general, those upon opposite sides
are raised  simultaneously, at others, those on the same
side; this latter gait is the amble.
   Leaping is performed by the sudden employment  of
various articulations of the limbs, which are at first more
flexed than usual.   The extent  of space the animal thus
passes through in  the  air, depends principally upon the
rapidity impressed upon its  body at  the  moment  of de-
parture, and this rapidity, in its  turn, depends upon the
proportional length of the bones of these members and
the force of their muscles.  Therefore, animals which leap
the best, have  the  hind legs  and thighs very long and
very muscular.
 mdflS  Swimming and flying are motions analogous to
those of leaping; save that they  are effected in fluids, the
resistance of  which takes the place, to a certain degree,
of that of the ground in  the preceding phenomena.
  The members, which by extending and bending back-
wards drive the body  forward, are  applied  in this case
against the water or air, and tend to  crowd together the
particles  of which these  media are composed  with a
greater or less rapidity; but if the resistance, which the
air or water presents in this way, is superior to that which
opposes the motion of the animal in a contrary direction,
these fluids will furnish to the limb a fixed point, and the
motion produced will be the  same as if this spring, touch- 
MOTIONS.
279
ing by its posterior extremity an invincible obstacle, only
expanded with a force  equal to  the  difference existing
between the rapidity employed and that impressed by it
upon  the surrounding fluid in bending backwards.  Now,
the less dense the fluid in which the animal moves, the
less resisting will be  the fixed point furnished by it;  and
the greater the force necessary to overcome, in rapidity,
this displacement of  the fixed point, and propel the body
forward.  Thus, flying requires  a much greater  motor
power than swimming, and neither of these movements
could be effected by the force requisite for a leap upon a
solid surface.  But this  great employment of the  motor
force  is not the only condition  necessary  for  aerial or
aquatic locomotion ;  as the animal  plunged in a fluid, finds
upon  all sides an equal resistance, the rapidity acquired
by striking upon this fluid behind, would soon be lost by
that which it would be  obliged to displace  in  front, if it
could not diminish considerably the surface of the locomo-
tory organs immediately after having made use of them to
give the blow.   This is the actual case, and one  of the
characteristics of every  organ of flight, or  even of  swim-
ming, is the power of changing its form and presenting,
in the direction  perpendicular to  that of  the movement
produced,  a  surface alternately  very  large   and very
narrow.
   With regard to the structure of the organs of aerial, or
aquatic locomotion, we will only say that in the superior
animals the thoracic  almost always alone serve  for flight,
and that their  transformation into  wings takes place either
by the extreme  elongation  of  the fingers, and the  exist-
ence of a membrane which extends between these appen-
dages, and is also fastened to the sides (as in  the bats, 
280
ANATOMY AND PHYSIOLOGY.
fig. 55), or by the implantation of long and stiff feathers
upon the whole extent of the limb, which  then becomes
     Fig. 55.     long and  narrow (as  in  birds).    The
                 abdominal and thoracic members  may
                 also serve for swimming, and when they
                 are  completely transformed into fins we
                 find, in general, that their terminal  part
     Fig. 56.      becomes  very large, and  that the  por-
                 tion which represents the arm and fore-
                 arm is shortened, so that the portion an-
                 alogous  to the  hand  seems  to  spring
                 directly from the  trunk: this is  easily
proved in the phocas and cetacea (fig. 56).

                      THE VOICE.
  In concluding the history of the functions of relation, it
it remains for us to  treat of the production of  sounds, a
faculty which in man is of extreme importance, as  upon
it depends  voice and speech.
  In the lower animals there is no  trace of this faculty,
and  in insects, the monotonous noise which is called the
hum of these little beings, merely results from the rubbing
of their wings, or  some other parts  of their tegumentary
envelope, against  each other; but  the  superior animals
nearly all can utter sounds more or  less  varied, the pro-
duction of which depends upon the passage of the air into
a determinate part of the respiratory duct, so arranged as
to impart vibration to this fluid.
  Larynx.   In man and the other  mammiferas,  this phe-
nomenon takes place in that portion of the air passage
which is situated at  the  top of the neck, between the
pharynx and  the  trachea, and called the larynx (fig. 16,
 
THE VOICE.
281
a ;  fig. 23, e; fig. 24, g).   In fact an  opening made in
the trachea below this  organ,  by permitting the expired
air  to escape  outwardly without traversing it, completely
prevents the  production  of sounds.  Examples are cited
of persons who with  such an opening in the neck, pro-
duced either by a wound or some  disease, have lost the
voice,  but  recovered  the  faculty of speech by putting a
close cravat around the neck so as to  stop  the wound,
and, consequently, force the air to follow its usual course.
On the other hand, a similar  opening  above the larynx
does not destroy the  voice ; whence  we  may with cer-
tainty  conclude,  that  the production  of sounds  takes
place in this organ.
  The larynx is a large and short tube,    p-ia. ^ i
which  is  suspended to the os  hyoides,      \
(h) and continues inferiorly into the tra-
chea.   Its  walls  are formed by  various
cartilaginous  plates,  designated  as  the
thyroid cartilage (t), the cricoid cartilage
(c), and the arytenoid cartilages; in front
we see the projection usually known  as       tr
Adam's apple (a) ; and in the interior, the mucous  mem-
brane lining it, forms, about its centre,  two great lateral
folds, directed from before backwards and arranged like the
lips of a button-hole.   These folds are called vocal  cords,
or inferior ligaments of the glottis ; they  are very thick ;
  1 Profile view of the human larynx ; h, os hyoides; — 7, body of the hy-
oid bone, to which is attached the base of the tongue; — t, thyroid carti-
lage ; — a, projection formed by the thyroid cartilage in front, and commonly
called Adam's apple; the thyroid cartilage is united to the os hyoides by a
membrane; —c, cricoid cartilage ;— tr, trachea ; — o, posterior wall of the
larynx in relation with the aesophagus.
                   36
lr	■■•g_^___s^___gj
	)Ca ll
a-	\j
t-	' "lllr
 
282
ANATOMY AND PHYSIOLOGY.
Fig. 58.•
Fig. 59.
                 their  length  is  in  proportion with the
                 projection of  the anterior part  of the
                 thyroid cartilage (or Adam's apple), and
               a  by the aid of the contractions of  a small
               v  muscle lodged  in their  interior,  and of
                 the movements  of  the  arytenoid carti-
                 lages to which they are fixed posteriorly,
they may  be approximated in a greater or less degree, so
as to enlarge or diminish the  space of  the  fissure (the
opening of the glottis), which  separates  them.   A little
above  the  vocal  cords,  are found two other  similar  folds
of the mucous membrane of  the larynx; they are called
superior ligaments of the glottis, and the  two depressions
                  which divide them  from the  inferior
                  ligaments,  are named  ventricles of the
                  larynx.   The space comprised between
                  these four  folds is called the glottis;
                  finally above this opening is a kind of
                  fibro-cartilaginous tongue, the epiglot-
                  tis, fixed by its base beneath the root
                  of  the  tongue,  and  which  ascends
obliquely into the pharynx, but which can be depressed so
as to cover the glottis, as  was exemplified when treating
of deglutition, (fig. 58, e).
   In the ordinary state, the air expelled  from the lungs

  1 Vertical  section  of the larynx ; — h, os hyoides; — t, thyroid carti-
lage ;— c, c, cricoid cartilage ; a, arytenoid cartilage;  — v, ventricle of the
glottis, formed by the space left between the vocal  cords and the superior
ligaments of  the glottis : — e, epiglottis.
  2 Front view of the larynx ; the shape of the internal wall is  indicated
by the lines a, a, b,b; — li, inferior ligaments of the glottis or vocal cords;
— Is,  superior ligaments.  The other parts are indicated by the same letters
as in  the preceding figures.
b b 
                       THE VOICE.                    283

traverses freely the larynx  and produces no sound in it;
but  when the muscles of  this organ  contract and the
passage of the air  becomes more rapid,  the voice may
be heard.  An  experiment by Galen demonstrates the
necessity  of  these contractions  for  the  formation  of
sounds.
   He divided in living animals the nerves supplying the
muscles of the  larynx ;x  and this operation, which occa-
sioned paralysis  of  these  organs, also involved  the loss of
the voice.  Other experiments also prove  that  the pro-
duction of sounds depends especially upon the action of
the  ligaments of the  glottis.   When  the superior  folds
are divided, the voice is considerably weakened, and when
the inferior, or vocal cords,  it is destroyed.
   Most physiologists consider the larynx as act-   Mechanism
         A  J     °                   J           of the produc-
ing in the production of the voice upon the prin- tion of sou,lds-
ciple of a reed instrument : they think, that the air ex-
pelled from the  lungs  rushes  out, in a continual stream,
from the lips of  the glottis, until these elastic cords  re-
turn upon themselves and momentarily close the respira-
tory  passage, to be separated  anew,  so  as to  produce
movements of vibration sufficiently rapid  to give birth to
sounds,  nearly the same things that transpire in  blowing
upon the reed of a hautboy.  But from the recent obser-
vations of M. Savart it would appear, that the production
of the vocal sounds does  not  depend upon  a mechanism
similar to  that of the  reed instrument, but rather takes
  1 The pneumogastric nerves, which arise from the lateral portion of the
medulla oblongata, issue from the cranium, descending one upon each side
of the  neck, and  penetrate into  the thorax and abdomen.  Immediately
after their entrance into the former of these cavities they give origin to a
branch, which ascends on either side of the  neck and ramifies upon the
larynx; it is called the recurrent nerve, from its direction, 
284           ANATOMY AND PHYSIOLOGY.
place in the same manner as in the little instruments used
by sportsmen to imitate the song of birds.
  These  instruments,  called bird-calls,  are  ordinarily
constructed of wood or metal,  and  consist of a small
cylindrical canal, very short and closed at each end by a
thin  plate, pierced in its centre by  a hole.   To  elicit
sounds, the sportsman places the call  between his teeth
and aspires the air through the two openings by which it
is pierced.  The current, which thus traverses the instru-
ment, draws  with it  a  part  of  the air contained in its
cavity, and the latter, being rarefied, soon ceases to be in
equilibrium with  the  pressure of the atmosphere, which
by its reaction crowds upon and compresses it, until, by
its own elasticity and by the influence of the current, it
undergoes a new rarefaction, followed by a  second con-
densation, and so on.  The small mass of air  contained
in the call thus enters into vibration, and gives origin to
sonorous waves, which scatter themselves  in the atmos-
phere.  By moderating, or accelerating the rapidity of
the current, we produce grave or acute sounds, and they
are varied yet more by enlarging or contracting the open-
ings of the instrument, varying its  form, rendering its
walls more or less elastic, and adapting to it tubes of  va-
rying length.
  It would appear that, by similar modifications of  the
larynx, the sounds produced  by this organ become grave
or acute.   As the voice ascends, the lips of the glottis
become tense and contract so as  to  diminish, to a great
extent, the size  of  the opening left between them.
The contraction of the  muscular fibres upon the  walls of
the ventricles of the larynx, and of the  muscles of  the
posterior fauces, give at the same time to all these parts 
THE VOICE.
285
a degree of tension favorable to the development of the
sound produced, and  we  find that the larynx itself as-
cends as  the  sounds are  more acute, a  circumstance,
which is explained by the laws of  acoustics, for it causes
the shortening of the passage traversed by the sounds in
making their exit, and we know  perfectly well that in
our ordinary instruments of music  the length of this pas-
sage has the  greatest influence  upon the  rapidity of the
sonorous vibrations ; when we  wish to draw from the
reed of a clarinet,  or hautboy,  for example, a succession
of sounds, we lengthen  or shorten  the tube  formed  by
the body of the  instrument, by closing or opening the
holes with which the walls are pierced.
   The  intensity or volume of the voice depends in part
upon the force  with which the  air is  expelled from the
lungs,   in part upon the  facility with which different
parts of the larynx vibrate, and  upon  the  extent of the
cavity  in which the sounds are produced.
   The  same individual cannot make heard, with an equal
degree  of force and clearness, all the sounds his larynx is
capable of producing, because the different parts  of his
vocal apparatus are not arranged in  a manner  equally
favorable to their production.  When a man is weakened
by fatigue or illness, his voice loses its intensity, because
the muscles which drive the  air from  the  lungs can  no
longer expel it with their ordinary force.
   Finally, it is to  the more considerable volume of the
larynx in man, that a part of the remarkable difference
between his voice and that of woman must be attributed ;
and owing to the existence of great  cavities in communi-
cation  with this organ, the howling apes, and some  other
animals, are able to make their deafening cries  heard to an
immense distance. 
286
ANATOMY AND PHYSIOLOGY.
  The pitch of the voice appears to belong in part to the
physical properties of the ligaments of the glottis and walls
of the larynx, and in  part to that of the following  portion
of the vocal canal.   We know from experiment that  the
pitch of musical instruments varies greatly, according  as
they are  constructed  of wood, metal, etc., and a  coinci-
dence has been remarked between certain modifications
of the human voice, and the more or less  hardened state
of the cartilages of the larynx.   In women and children,
whose voices have a  peculiar  pitch, the cartilages  of the
larynx are flexible  and have but little  hardness, while  in
men and women with a masculine voice, the thyroid car-
tilage is remarkable for its power, and more or less com-
plete ossification.
  The form of the  external opening of the vocal apparatus
exerts a great influence upon the tone of the sounds pro-
duced.  When the sounds traverse the nasal fossas only,
they are disagreeable and  nasal; when the mouth is wide
open the voice acquires, on the contrary, power and  bril-
liancy, and it would appear that the degree of tension  of
the velum palati and of the other parts of the fauces, ex-
ercises an influence not less  great upon  the manner  in
which sounds are modulated.
  From what has been said of the mechanism of the pro-
duction of sounds, it must be inferred that the diapason
of the voice depends in a great degree upon the  length
and thickness of the  vocal cords.  The voice of man, as
every one is aware, is much graver than that of woman ;
because, in man, where the larynx makes at the superior
part of the neck a considerable prominence, known by the
vulgar name of Adam's apple, these folds are much longer
than in  woman, where  the antero-posterior diameter  of 
THE VOICE.
287
this organ is so small that the  eminence alluded to can
hardly be distinguished.
  The sounds produced by the vocal apparatus have not
always the same character, and are  consequently distin-
guished into cries, singing, and the ordinary voice.
  The cry is a sound usually acute and disagreeable, cry.
which is  but little or not at all modulated, and which prin-
cipally differs from the other vocal  sounds by its  pitch.
It is  the only one  formed  by the  majority  of  animals,
and, in this  respect, man  differs  from the  latter  only  by
education.  The infant just  born  can utter only cries, and
when deprived of the sense of  hearing its voice does not
change; but when it understands what passes around it,
it learns  from its equals to  modulate it,  and to  produce
sounds of a particular nature.
   This acquired voice differs from the cry by its  Avo!cefd
intensity and pitch ; but it is not  formed in the  same
manner  as sounds, the intervals  and  harmonic relations
of which are not clearly distinguished by the ear.  singing.
Singing, on the contrary, is composed of appreciable or
musical  sounds, in which, so to  speak, the ear reckons
the relative number of vibrations.
   Man also possesses the faculty of modifying, in  a par-
ticular manner, the various sounds of his voice ; he may
articulate these sounds, and to this act is given the  name
of pronunciation.
   The organs of pronunciation are the pharynx, of^0tuinud,3ation
nasal fossas, and the different  parts of  the mouth; and
according to  the  manner in which they  act, the sound
produced by the larynx varies in its character, and con-
stitutes  a particular articulated sound.
   The  articulated  sounds  are  divided into  two  great 
288
ANATOMY AND PHYSIOLOGY.
classes, vowels and consonants.  The former are perma-
nent and simple  sounds, which cannot be confounded by
union with others, and during the production of which
the apparatus of pronunciation remains unchanged ; the
consonants  are,   on   the  contrary,  articulated  sounds
which  it is impossible  to  prolong  as the vowels, and
which require for their production, particular movements
of the apparatus of  pronunciation,  movements in the
course of which  this apparatus necessarily takes the dis-
position by means of which it forms a vowel.  Thus, the
consonants can only be articulated by the addition of the
sound of a vowel.   They are divided into labial, dental,
nasal, etc., consonants, depending upon  the part  called
into action  in the  mechanism of their  pronunciation,
whether the lips, tongue, etc.
  Man  is  not the  only animal having  the  faculty of
articulating sounds,  and thus to pronounce words ; but
he is the only one which attaches a meaning to the words
pronounced and to the arrangement  he gives them; he
alone is endowed with the power of speech.
          FUNCTIONS OF REPRODUCTION.

  The various vital phenomena,  which have hitherto
occupied our attention, all have respect to the  preserva-
tion of the life of the animal, or to its relation with sur-
rounding objects.   Those now remaining to be  noticed
are of another  order ; their object is the multiplication of
the individuals and the preservation of the species.   We 
FUNCTIONS OF REPRODUCTION.           289
 have as yet only studied beings completely formed ;  we
 are  now to inquire  into their origin, and  the mode  of
 their development.
   The primitive creation of organized beings is  (S/
 a subject which at first sight appears inaccessible to sci-
 ence ; but the genius of a man, of whom France may
justly boast, Cuvier,1 has dispersed a part of the profound
 darkness which enshrouded this great mystery, and taught
 us, at least, the order in  which the different animals suc-
 cessively appeared upon  the surface of our globe.
   This earth  has not always had the configuration it now
 has.   Its various parts have  been, on several  occasions,
 invaded and abandoned  by the waters, and  by each  in-
 undation  solid matters  have  been deposited, which,  in
 the course of time have  formed more or less thick  layers
 of stone, clay, sand, etc.,  placed  one  above  the  other,
 according to  the recent  period of their  formation.  In
 the primary strata  or formations, no trace is found  of the
 remains of organized beings ; but as we ascend and ex-
 plore the layers of more recent formation, we meet in the
 fossil state with wood, leaves, shells and bones of various
 forms; sometimes these remains are  in  such quantity
 that the stone seems formed  by them, and their preser-
 vation is often so perfect that it is easy to determine  to
 what plants, or animals,  they must belong.
   The study  of these remains, which  have  survived  all

  1 M. George Cuvier was born at Montpellier in 1769, and died at Paris
in 1832.  His principal works are : Researches upon Fossil Bones, 5 vols.
4to; Lessons in Comparative Anatomy, 5 vols. 8vo; his general  classifi-
cation of animals entitled the Animal Kingdom, divided according to its
organization, 5 vols. 8vo; and  his Memoirs upon the Anatomy of the
Mollusca, 1 vol. 4to; but science has also been benefited in many ways
by his indefatigable labors.
                   37 
290
ANATOMY AND PHYSIOLOGY.
the great catastrophes so often overwhelming the surface
of the earth, demonstrates that our globe, originally des-
titute of living beings, was at first peopled by vegetables
only, and that the first animals  which appeared  were
beings of  a very inferior structure, the species  of which
have been for  a long time destroyed.   They were pro-
bably aquatic animals,  analogous to  the sow-bugs and
called by naturalists trilobites, or  marine mollusca, living
in large shells, and called ammonites, or  horns of Ammon.
At a more recent period, our globe has been  inhabited
not merely by conchiferas, analogous to  those formerly
existing, but also by many enormous  reptiles, frequently
of a most singular form.   The  mammiferas  do not ap-
pear till some time after, and those which have  succes-
sively  peopled  the earth have  approached  nearer and
nearer to the species actually inhabiting it.  Finally man
appears to have been the last, as he is  the most  perfect
of these creations, for we find none of  his bones in the
fossil state.
   Thus nature has gone on constantly  complicating and
perfecting her works, and, by many intervening degrees,
she has ascended from the production of a plant  to that
of a man.
   At every great catastrophe of nature, several of the
existing species have been completely destroyed and re-
placed by new ones, so that  each of  the epochs of the
antediluvian history of  our globe is characterized by its
particular  population;  but other  species appear to have
survived these changes; and, according to the opinion  of
certain naturalists, some of the  animals which then ap-
peared were of the species now  existing, but modified  in
their structure by the influence of the  new condition  in
which they are placed. 
FUNCTIONS OF REPRODUCTION.          291
  However the case may be with  these  entirely new
creations, or with these transformations of beings already
existing, it is evident, that from  the most remote  period
of history, animals have succeeded each  other with  the
same forms.  At the present day we find  in the cata-
combs  of ancient  Egypt, mummies  of men, jcrocodiles,
and  several other  animals, which have been  buried in
them for two or three thousand years, and which resem-
ble in all points the individuals now existing.
  Their mode of origin also explains  in a degree  this
reproduction of the identical forms for a long succession
of ages, while  the beings which present them, all perish
at the expiration of  a short time, or even a few days.
They actually at first form a part of the body of another
organized being, which transmits life to them, and is in
some sort the model after which they are constituted.
  It was formerly a received opinion, that mat-  ^"S
ter placed in favorable physical conditions might be organ-
ized of itself, become the seat of a vital movement, and
thus give birth  to animals but  slightly complicated, such
as the  flies upon carcasses, etc.;  but at the  present  day
we  know  positively, that in  the immense majority of
cases, if not always, animals can only arise from  parents
similar  to themselves ; and  that  if spontaneous genera-
tion be possible, it  is only in beings with  the  simplest
structure, as the monads, which appear in  the  infusions
of vegetable and animal  matter, and which  seem to be
mere agglomerated  organized  globules,  in a larger or
smaller number, and endowed with motion.   Their mode
of formation is a disputed point among naturalists ; ac-
cording to  some, these infusies, as well as  many other
microscopic globules, are  exceptions to the general law, 
292
ANATOMY AND PHYSIOLOGY.
and are formed spontaneously ; while, according to others,
they always arise from the germs of individuals similar
to themselves, abundantly diffused  in  nearly all  organic
substances, and only developed  under certain  favorable
circumstances.
  ge^ratton.   But if it is the essence of organized beings to
arise from parents like themselves,  the manner in which
this reproduction is effected varies  greatly in the differ-
ent animals, and  we are thus furnished  with  a  striking
example  of the application made  by nature of  the prin-
ciple of  the division of labor, when she  has desired suc-
cessively to perfect the beings of her creation.
 GbyesrHps°.n    1°  tne simplest  animals, the  important  func-
tion of generation does not appear to be  confided to any
organ in  particular;  all parts of the surface of the body
of one of these animals are capable of  giving origin to
small slips, which increase in size, and soon become new
individuals, similar in every respect  to that from which
they spring.   The polypi, of which we have already had
occasion  to speak (fig. 1) are  thus  reproduced by slips;
but this mode  of propagation of the species is only met
with in a very small number of the most  inferior animals,
 g°nePrat?on.  and in all others the germ, which by its devel-
opment is to constitute the young, is formed in a partic-
ular organ, called the ovary.
   When these organs first  display themselves in  the
zoological series, they have a very simple structure ; they
are in  general mere  glandular vessels, and the germs
they produce are adapted for development without  the
consent of any other apparatus ; but the  division  of labor
is  soon extended ; and reproduction is entrusted  to two
distinct organs, the consent of which is  necessary to the
birth of a new individual. 
             FUNCTIONS OF REPRODUCTION.          293

  These two kinds of apparatus,  one serving for  the
production, the other the fecundation of the germ, and
called female and male apparatus, are at first united  in
the same individual, which of itself alone is charged with
the whole labor of reproduction.  Oysters, muscles, and
many other inferior animals present this mode of genera-
tion.   In others, where the sexes are still united, snails,
for  example, hemaphroditism is less  complete  : for  the
fecundation  of the  germs  can  only  be effected  by the
individual producing them.  But, as we  ascend  in  the
series of beings, we find nature pushing yet  farther  the
division of labor;  for then the sexes are  always sepa-
rated.   This is the case  with all the superior animals,
quadrupeds,  birds,  fishes,  etc., and even  with insects,
spiders, the Crustacea and some mollusca.
  In most fishes, and even some reptiles, the fecundation
of the germ does not take place till after the  expulsion
of the ova, and is in some degree  confided to chance;
but in  the superior  animals, it is better ordered  and takes
place before their expulsion.  In general, the germ, after
being detached from the  ovary and fecundated, has  no
longer need of the assistance of  its parents for develop-
ment.   Abandoned to itself, it  gives birth to a new indi-
vidual, which carries with it  the  materials necessary  for
its nutrition during the entire life of the embryo ; but in
birds, the egg, which is composed of the germ, nutritive
substances just mentioned, and the  membranes contain-
ing them, is only developed by the  influence  of ™%S.
an  elevated  temperature,  which the mother  ordinarily
maintains by incubation.   Finally,  in other animals  the
series  of the phenomena of reproduction is  yet more
complicated ; for  the  germ  does  not carry  with it  its 
294
ANATOMY AND PHYSIOLOGY.
nourishment, and to live after being detached  from the
ovary  and fecundated, it must  contract  new  vascular
adherences with the walls of a particular sac, called the
womb, which is destined  to lodge the young individual
until all its organs are formed.
   The  animals, whose germs do not  thus draw their
nutrition from the blood of  the mother, are called ovipa-
rous ; those which  present the latter mode of reproduc-
tion are  called viviparous,  because in place of being
developed  in  an  egg  they are  born  alive and ready
formed.
   All the inferior animals which are not reproduced  by
slips, such as worms, the mollusca, the Crustacea, insects,
etc., are  oviparous: so are  fishes, reptiles, and  birds;
but man and all animals  closely  allied  to  him, such as
the domestic quadrupeds,  etc., are viviparous.
 "fThefetus.1   When  the young  individual begins  to  be
developed in the germ, it  is not, as might  be supposed,
the miniature of what it will become at a  later period.
It does not at all  resemble its parents,  and  has  neither
its future form, nor structure.  Its organs appear in suc-
cession,  and they undergo  during  their evolution very
remarkable changes.   We may say in a general manner,
that the entire organization of the  embryo, as  well as
each of its parts considered  separately, passes through a
series of transitory  stages, which resemble to a  certain
degree the permanent  condition of some animal less  ele-
vated in the scale.   The human embryo, for example, in
the earliest moments of its  existence presents  a mere
round mass, destitute  of limbs, having  some analogy in
structure to certain  very simple animals; for we  find in
it neither brain, heart, bone, nor distinct muscles.  The 
             FUNCTIONS OF REPRODUCTION.          295

heart at first resembles that of some worms, a mere ves-
sel, which soon curves and presents two dilatations, form-
ing the left auricle and  ventricle.   It  then  exhibits a
mode of conformation analogous to that of some fishes;
the auricle is afterwards divided into  two cavities by an
incomplete  partition, which resembles the  structure of
the heart in most reptiles, and at a little later period, a
second partition  which arises from  the bottom of the
ventricle also divides this into  two, so that the heart then
presents two cavities as we  find it in the  superior ani-
mals.  But yet the circulation of the foetus  is closely
allied to that of the reptiles;  for the  two auricles com-
municate by a  hole called  the foramen  ovale,  and  the
pulmonary artery is joined to the aorta by a large anas-
tomotic branch, so that only a small portion of the blood
driven from the right ventricle reaches  the lung, while
the remainder mixes with the  blood destined for the im-
mediate nutrition of the organs.
  The development of the  embryo can  be more closely
watched in the egg, therefore we shall select it as an ex-
ample for  the study of this curious phenomenon.
  Birds have  not, as  most of the superior animals, two
ovaries.  We find in them only one, which is fixed in the
abdominal  cavity in front of the vertebral column by a
fold of the peritoneum, and  which consists of a collection
of small membranous sacs,  rounded,  more  or  less devel-
oped, and united  in clusters.   The walls of  these sacs
abound in blood vessels, and  secrete the ovules, which
are formed in  their  interior  and which consist of a yel-
low material, enveloped in a  very thin membrane.  These
bodies slowly enlarge, and  when they have acquired the
volume to be possessed by the yellow  of  the perfect egg, 
296
ANATOMY AND PHYSIOLOGY.
the ovarian sac, in which each of them is contained, bursts
and allows it to escape into the cavity of the pavilion, a kind
of membranous tunnel applied upon the ovary and conduct-
ing outwardly by the oviduct, a tube of the same nature,
the inferior orifice  of which is  seen in the cloaca, near
the anus.   At the  moment when the ovule descends into
the oviduct, it is merely composed of vitellus, or yellow,
enveloped in  a membranous sac, at one point  of which is
a whitish spot, called the cicatricule, and which deserves
notice, because in  its interior the embryo is to be devel-
oped ;  but, in proportion as the ovule descends, it is cov-
ered by other substances  secreted by the walls  of the
canal it traverses.   About the middle of the oviduct it is
enveloped  by a thick and glairy matter,  which  is  the
white of the  egg,  and a little lower down there is formed
around this new layer a thick membrane, the external
coat of which is finally encrusted by an earthy deposite,
and thus constitutes the shell of the egg.
   In  this condition the  egg is laid.  When it has not
been previously fecundated, it does not  undergo any im-
portant change ; but, in the opposite case, it becomes the
seat of an active  progress  as soon  as its  temperature is
suitably elevated.
   If the cicatricule, which is about six millimetres in  di-
ameter, be now  examined  by the microscope, there will
be seen towards the centre a small white oblong body
which may be considered the rudiment  of the germ, and
which presents a central white line rounded at its sum-
mit ;  this spot marks the  place  in  which the cerebro-
spinal cord will be developed, and,  according  to some
physiologists,  it is itself the first appearance  of the ner-
vous system.   Around the germ, is seen a kind of mem- 
             FUNCTIONS OF REPRODUCTION.         297
branous and transparent disc which in its turn,  is bor-
dered by a darker  zone and  by two concentric  light
circles.   About  the  eighteenth hour of incubation, the
germ contracts,  takes  nearly  the form  of a  lance, is
rounded  at its superior part  and forms  a fold, which
doubles like a cloth in front of  the cephalic extremity of
the cerebro-spinal line.   Upon the sides of this longitu-
dinal line may also be remarked two small ridges, which
enclose it as  in a canal.  Soon after these ridges unite
by their  inferior extremities and  approach so as to con-
ceal the  line which separates  them ;  finally,  about the
twenty-fourth hour,  three pairs of rounded points make
their appearance which are  the first  rudiments  of the
vertebras, the number of them now rapidly increasing.
  The transverse fold alluded  to  upon the anterior ex-
tremity of the germ, is the first rudiment of the head,
which soon tends to detach itself and become  distinct.
Toward  the thirty-sixth hour  of incubation the  eyes of
the  pullet may  be  perceived ; soon after, the posterior
part of  the  body is plainly  defined,  and the embryo
curves upon itself.   During the  third day the head be-
comes more  and more   distinct;  its pointed  extremity
which corresponds to the beak, is bent upon the chest,
and  on the sides of the  vertebral column  under the form
of small white  tubercles may be recognised the  earliest
traces of  the upper  extremities ; soon  after,  the  inferior
limbs are formed in  the  same manner ;  two small appen-
dages fixed below the  neck also  appear, and constitute
by  their  development  the lower jaw ; finally, the eyes
are  colored black.   The fifth day of incubation, the
limbs, which as yet  resemble mere stumps without form,
begin to execute some  slight  motions, and twenty-four
                    38 
298
ANATOMY AND PHYSIOLOGY.
hours after they are so far developed  that the thighs can
be distinguished from the legs, and the fore-arm from the
arm:  the general form of the individual also approaches
a little to what it will be in future ; about this period the
heart enters the cavity of the chest, and the walls of the
abdomen are completed.   The  seventh day the  feet are
formed, and about the  ninth day, upon  the skin of the
embryo,  may be found  little pores, which are the open-
ings of  the  capsules  destined  to secrete  the  feathers,
which begin to make  their appearance at the end of the
tenth day, and cover the  whole  body in  the space  of
twenty-four hours.  The size of the head, at first exces-
sive, diminishes proportionally to that of the rest of the
body, and the eyes, which were  remarkable for their  size,
increase  more slowly than the other parts ; the limbs, on
the contrary, are developed with greater rapidity, so that
the entire  chick approaches more and more nearly the
perfect animal.
   Considered with regard to its  external form  merely,
the embryo presents, as we have seen,  true  metamor-
phoses ;  but  the most curious part of the history of its
development is that which  displays the manner in which
the different sets of apparatus, most important to life, are
successively formed in the interior of  its  body.
   About the twenty-seventh hour of incubation, on the
anterior face of the pullet and precisely at the point where
the membrane folded in front  of the head terminates,
may be perceived a small transverse cloud, which enlarges
at its two extremities,  and  is insensibly lost  upon the
transparent area in  the middle of which  the germ  is
placed.   This cloud is the rudiment of the  left auricle of
the heart.   Three hours after the centre of this organ 
FUNCTIONS OF REPRODUCTION.          299
will be found  surmounted by a  straight vessel directed
towards the head, and which is  the  left ventricle;  soon
after,  a third enlargement is seen above the latter, it is
the bulb of the aorta which afterwards disappears, but is
permanent in certain reptiles such as  frogs ; the heart
then enlarges  and curves upon itself; a contraction is  es-
tablished  between  the auricle  and  the ventricle,  and,
about the thirty-sixth hour, the former of these cavities
begins to ascend to the summit of the apparatus:  at this
period the heart  begins to beat,  but  it does  not yet con-
tain blood, and is only filled by a colorless liquid.   From
the earliest hours  of incubation, the  transparent area
around  the germ also presents important modifications:
the membrane forming it is divided  into two leaves be-
tween which is developed a layer of  spongy tissue which
about the thirtieth  hour begins to thicken  in  certain
places, and to take  a yellow  tint; this tissue gradually
extends over the whole surface of the yellow, and  little
islets  filled with a reddish liquid form  in  its interior ;
finally these soon communicate together  and form a vas-
cular  net-work, which surrounds  the embryo  and sends
the blood  to  the heart by two vessels, the  extremity of
which is lost  in  the left auricle.   The blood  is at first
formed in this vascular membrane  and far from the em-
bryo ; and when it begins to appear, its globules are cir-
cular.   The circulation is then easily  traced: the blood
passes through the  ventricle, arrives  in the  bulb of the
aorta, thence  enters  the  descending  aorta,  which soon
divides into two  branches, which issue from the body of
the foetus and are lost in  the vascular area by which it is
surrounded; the blood which thus  leaves  the chick on
the right and  left, is divided into  a collection of capillary 
300
ANATOMY AND PHYSIOLOGY.
vessels, then runs into a general vessel which conducts it
upward or downward, whence it returns to the heart.
Between  the third and fourth day of incubation, the right
ventricle  may be  clearly distinguished  and appears as a
small sac  placed  in front of the left ventricle, communi-
cating freely with the cavity of the auricle and continu-
ous  with  a vessel, the  extremity  of which  is  directed
towards the point  occupied by the lungs.  On the second
day, the right auricle also begins to be formed by means
of the development of an annular fold, which divides the
left auricle  into two distinct  parts.  Finally, about  the
sixth day, we begin to perceive  in  the  blood  elliptical
globules,  and the  ninth day these have taken the  place
of the  circular  globules which  at  first  existed alone ;
their  appearance  coincides with that of the liver, and
with the obliteration of the vessels  of the membrane of
the yellow, in  which we found  sanguification  to  com-
mence ; therefore  there is reason to  consider  this viscus
as the seat of secretion of these corpuscules.
   The lungs begin to be developed about  the fourth day ;
at first they consist of two oblong,  almost transparent
tubercles  placed behind the heart; they soon acquire a
reddish tint,, but do not serve for respiration  till the chick
has broken its shell.
   This function is however very actively  executed from
the earliest  moments of incubation ; and  if air be  pre-
vented from penetrating  the egg, the chick dies almost
immediately.  At the  moment when  laid, the egg is
completely filled  by the white  and  the yellow, but these
liquids gradually lose by evaporation  a certain  quantity
of their water, and there is thus  formed  under  the shell
a vacuum  filled with air :  at  the  same  time the yellow 
              FUNCTIONS OF REPRODUCTION.          QQ\

undergoes important modifications which render it lighter
than the white, so  that  it occupies the superior  part of
the egg whatever be its position ; and the serosity, which
accumulates during the second  day of  incubation under
the  cicatricule, producing  the same  effect  upon  this,
causes it to float so as to be in contact with the air spoken
of.   The respiration of the embryo is at first  effected by
the contact with the air which  has  thus  penetrated  be-
neath the shell, or by the membrane of the yellow ;  but
soon  after,  this  function becomes  the duty of- a  new
membrane called allantois.  This begins to make  its ap-
pearance about  the forty-fifth hour of  incubation, under
the form  of a  membranous  and transparent vesicle, of
the size of a pin-head, placed in the abdominal region of
the chick.  This sac  is rapidly  developed, expands upon
the superior surface of the yellow, and finally occupies
the whole internal surface of  the shell  against which it
is placed.  Lastly, its  external leaf is quickly covered by
a magnificent vascular net-work, which receives the ve-
nous  blood coming from the embryo,  and places it  in
contact with the air to be transformed into arterial.
  The intestinal canal appears to originate by two folds
of the internal  layer of the cicatricule,  which at first re-
semble tunnels open at one end, situated above the ver-
tebral column and opposite each other;  these  folds grad-
ually contract and close ;  but their  cavity still remains in
communication with the  yellow, which  little by little en-
ters it and serves to nourish the foetus ; thus  it is more
and more diminished, and towards the end of incubation
it is introduced into the interior  of the abdomen.
  Finally, the nervous system undergoes, in its develop-
ment, a series of modifications yet more remarkable than 
302
ANATOMY AND PHYSIOLOGY.
those we have observed ;  and the transitory forms seen
in it have the greatest  analogy with  the permanent con-
dition of these same parts in animals less elevated in the
zoological series.
   The  majority of animals have, on coming into the
world, nearly the forms  and  the  mode  of organization
they are to preserve during  the  whole of life, but it is
not so with all;  there are many  which,  even after birth,
pass through changes analogous to those already expe-
rienced  during  the development of their  embryo, and
sometimes these changes are so complete that the animal
undergoes true metamorphoses before reaching the per-
fect state.  Frogs and especially insects furnish remark-
able examples of these transformations. 
APPENDIX.
                     Page 25, Line 8.
  The value of the millimetre according to the best authority
being only .03937 portion of an inch, we can conceive, that it
must require a microscope of no small power to display these
corpuscles of the blood ; those of the blood of man being only
.00026 of an  inch  in  diameter according to this calculation.
For a description of the globules and  of the peculiar proper-
ties of the vesicle,  and of the nucleus, the reader may consult
the recent works upon the Blood ; those of Magendie. Schultz,
Andral, Ancell, etc.


                     Page 26,  Line 20.
  The non-coagulability of the blood  as  resulting from elec-
tricity has been denied by some writers.  The following account
is given by Scudamore in his Essay upon the Blood.   " Ex-
periment LII.   A strong mongrel dog was the subject of the
experiment.   By means of a very powerful electrical battery,
constructed by Mr. Woodward at the Surry Institution, the
animal was killed  after several shocks.  On  inspection  next
morning, the  blood in the cavities of the heart, and in the
vena cava, was found quite coagulated.
  " I made a similar experiment with rabbits, with the same
result • and  in these smaller  animals, death was effected in-
stantaneously." 
304
APPENDIX.
                     Page 29, Line 27.
  Transfusion, as originally performed, is an instance of the
gross errors into which practice, unsupported by theory, may
fall.
  " The operation of transfusion," says Dr.  Palmer, in his
notes  to Hunter on the  Blood, " was first  performed on the
human subject  in France, by MM. Denis  and Emmerts, on
the fifteenth of June, 1667, and repeated  in England by Drs.
Lower  and  King on the twenty-third  of November of the
same year.  It speedily grew into  favor; but in consequence
of the fatal  and dangerous  effects which ensued in several
cases, it was  interdicted  by a sentence of the  Chastelet, and
soon afterwards fell into desuetude."

                     Page 57, Line 20.
  In an essay upon the Blood by W. Stevens this doctrine of
Endosmosis is fully considered, and some sources of error on
the part of Dutrochet clearly pointed out.  The passage is too
lengthy to be extracted,  and therefore my readers had  better
consult  the work in question.
  The value of the centimetre is .39371 of  the inch.

                     Page 84, Line 28.
  The value of the litre being 61.028 English cubic inches,  it
follows  that the average consumption of oxygen by individu-
als would be not far from 45771 cubic inches,  or 1585  pints
per  day.  While the  consumption of atmospheric air for the
same  space of time would amount to 213598  cubic inches,
rather more than 7398 pints.

               Page 95, Fourth Paragraph.
  The apparent contradiction in this paragraph to the closing
line of page 84 arises from the fact, that in the present in- 
APPENDIX.
305
stance the author considers  the  use of the atmospheric air,
and in the other case the actual expenditure of this fluid was
stated.


                         Page 98.
  Many experiments upon the subject of animal heat with the
view of determining its nature,  cause, etc., have been made
within a few years by  the physiologists  of Europe ; among
the most interesting are those by Dr.  Alison, and by Edwards,
(the brother of the  author), detailed in  his work upon the
effects of  physical agents upon life.


                    Page 106, Line 25.
  The following description of the plant bearing the cashew-
nut is taken from  the United States Dispensatory of Messrs.
Wood and Bache.
  "Anacardium Occidentale, Linn. Cassuvium pomiferum,
Lam. Cashew-nut.  A small and  elegant tree,  growing in the
West Indies, and  other parts of tropical America.   A gum
exudes spontaneously from the bark, which bears some resem-
blance in  appearance to gum  Arabic, but is only in part solu-
ble  in water, and consists of  proper gum and  bassorin.   It is
the gomme d acajou of the French writers.  The fruit is more
important.  It  is a fleshy, pear-shaped receptacle, supporting
at its  summit a hard, shining, ash-colored, kidney-shaped nut,
an  inch or more in length, three  quarters of an inch broad,
consisting of two shells, with a black juice between them, and
of a sweet oily kernel within the inner shell.   The receptacle
is of a red or yellow color, and of an  agreeable sub-acid fla-
vor with some  astringency.   It is edible,  and  affords a  juice
which has been recommended as a remedy in dropsy.  This
juice is converted by fermentation into a vinous liquor, from
which a spirit is obtained by distillation, much used in making
punch, and said to be powerfully diuretic.   The nuts are well
                    39 
306
APPENDIX.
known  under  the name  of  cashew-nuts.   The black  juice
contained between their outer  and  inner shell, is  extremely
acrid and corrosive, producing,  when applied to the  skin, se-
vere  inflammation,  followed  by blisters  or  desquamation  of
the cuticle."
                       Page 107, Line 9.

  A beautiful instance in our own language is Byron's admi-
rable picture of the  Prisoner of Chillon.   It will not perhaps
be considered  amiss, to introduce in this place the passage of
Dante referred to as given in the version by Cary.

                             " When I awoke,
          Before the dawn, amid their sleep I heard
          My sons (for they were with me) weep and ask
          For bread.  Right cruel art thou, if no pang
          Thou feel at thinking what my heart foretold ;
          And if not now, why use thy tears to flow ?
          Now had they wakened ; and the hour drew near
          When they were wont to bring us food ; the mind
          Of each misgave him through his dream, and I
          Heard, at its outlet nnderneath lock'd up
          Th' horrible lower : whence, uttering not a word,
          I looked upon the visage of my sons.
          I wept not:  so all stone I felt within.
          They wept: and one, my little Anselm, cried,
          ' Thou lookest so ! Father, what ails thee ? '  Yet
          I shed no tear, nor answered all that day
          Nor the next night, until another sun
          Came out upon the world.  When a faint beam
          Had to our doleful prison made its way,
          And in four countenances I descry'd
          The image of my own, on either hand
          Through agony I bit; and they, who thought
          I did it through desire of feeding, rose
          0' the sudden, and cried ' Father, we should grieve
          ' Far less, if thou would'st eat of us ; thou gav'st
          ' These weeds of miserable flesh we wear,
          ' And do thou strip them off from us again.'
          Then, not to make them sadder, I kept down 
APPENDIX.
307
          My spirit in stillness.  That day and the next
          We all were silent.  Ah, obdurate earth !
          Why open'dst not upon us ?  When we came
          To the fourth day, then Gaddo at my feet
          Outstretched did fling him, crying, ' Hast no help
          ' For me, my father!'  There he died ; and e'en
          Plainly as thou seest me, saw I the three
          Fall one by one 'twixt the fifth day and the sixth:
          Whence I betook me, now grown blind, to grope
          Over them all, and for three days aloud
          Call'd on them who were dead.  Then fasting got
          The mastery of grief." — Canto xxxiiii.

                      Page 110, Line 1.
   The term ' cul-de-sac'  may be applied to any cavity desti-
 tute of an outlet, although provided with an entrance.

                      Page 118, Line 7.
   This period  is not entirely free  from  danger  and calls  for
 the lancet to avert  many secondary evils.  Many a babe  has
 fallen a victim  to hydrocephalus  from the fear of the gum-
 lancet on the part of the mother.  In  all  diseases  of infancy
 there is so frequently some complication with  the  cutting  of
 the teeth, that it is  by no means an  unwise practice to put a
 finger in the mouth for its examination.

                      Page 124, Line 7.
   The common expression,  " the  palate 's  down,"  means
 neither more nor less than  that from a relaxed state the uvula
 rests upon the  base of the tongue, where  by its irritation  a
 constant hacking, tickling cough is kept up.


                     Page 129, Line 20.
   Probably the most remarkable  series of experiments ever
performed  upon the  living subject were those of Dr.  Beaumont 
308
APPENDIX.
upon Alexis St. Martin.  The latter individual was wounded
by the bursting of a gun in  such a  manner that a perforation
into  the stomach  took  place ;  after  a long period the wound
cicatrised and healed, leaving  the opening closed merely by a
valve which could  be raised and the whole action of the sto-
mach brought into view — pieces of food could be introduced,
gastric juice extracted, etc.


                     Page 142, Line 3.
  This important question is still mooted, but will not proba-
bly long remain so; the attention  of physiologists  is chiefly
directed to its adjustment at the present time.
                    Page 152, Instinct.
  Cases  now  and then occur, in which  this faculty seems
closely allied to an effort of the  reasoning powers, but how-
ever near, there is no evidence that an animal is  capable of
reflection — it may take cognisance of outward events, but it
lacks the capacity of investigating the mind as such.


                  Page 154, Line 3 —16.
  This comprehensive law of  development is thus beautifully
expressed by Solly in his work upon the brain.   " The mature
human frame, which in  its perfect adaptation to fulfil the ends
of its existence strikes the philosophical anatomist with admi-
ration, does not result from the gradual increase of an exact
though minute representation  of its perfect form; but during
the course of its  development, and while  gradually progress-
ing towards its ultimate perfection, its constitution temporarily
assumes  many forms, which are permanently retained by one
or other of the members among the lower orders of creation."
p. 226. 
APPENDIX.
309
                    Page 165, Line 24.
  Because nerves from  the ganglionic system are sent to the
vessels, it has been inferred, that the blood  itself was under
the influence of this system.

                    Page 171, Line 20.
  M.  Magendie only confirmed by his experiments what Sir
Charles Bell  had previously demonstrated by actual  experi-
ment  to be the case.

                    Page 194, Line 12.
  An operation, from which some benefit has been derived in
deafness, consists in the  introduction into  the outlet of the
eustachian tube (w, fig. 31),  of a  minutely perforated  tube,
through which air is thrown by a machine into the cavity.

                    Page 211, Line 13.
  The contraction of the internal rectus  muscle gives rise to
strabismus or squinting ; for the relief of this deformity Profes-
sor Dieffenbach of Berlin proposed the division of the  muscle.
As  the subject possesses so much interest 1 will  extract from
the Am. Jour, of  Med.  Science for August, 1840, an  account
of his mode of operating.
  " The subject of  this operation was a child seven years old,
whose eye was drawn far into the inner  angle of the eyelids
so as  to produce  considerable  disfigurement.  The operation
was performed in the following manner: — The  head of the
child was held against the chest of one assistant, while  another
with two hooks kept the eyelids widely apart.  The operator
then passed a third hook,  which he gave to a third assistant
to hold, through the conjunctiva, and  to  some depth in  the
subjacent cellular tissue  at the internal  canthus.  He next
fixed  a fine double  hook in the sclerotica at the inner angle, 
310
APPENDIX.
and, taking it in his left hand, drew the eye outwards.   Then
cutting into the conjunctiva close to  the ball, where it is con-
tinued from it to  the  internal canthus, and penetrating  more
deeply by separating the cellular tissue  by the side of the
sclerotica, he divided the internal rectus  muscle close  to its
insertion with a fine pair of scissors.  The eye was immedi-
ately drawn outwards by the external rectus, as  if it had re-
ceived an electric shock;  and  in  another instant  became
straight,  so that there was no difference  perceptible between
its direction and that of the  other eye."
  He has been followed by several, who have variously mod-
ified his  mode  of operating, not only in  Europe  but  also in
this country.  In the  Boston Med. and Surg. Journal, Decem-
ber 2d, 1840, are  six cases of the operation as performed by
J. H. Dix, M. D., among the earliest cases to be found in the
surgical annals of our country.

                     Page 212, Line 31.
  If each eye has its own optic nerve, why do we not perceive
two images?
  "The  rays of light from any  object, placed laterally, im-
pinging upon the  retina of both  eyes,  will  strike  the  outer
side of one eye and the inner side of the other ; now, * * * *
it follows as a necessary consequence, that the outer and  inner
side of each opposite  retina is formed by one and  the  same
nerve, a peculiarity of structure that goes far to account for
the circumstance so often reasoned upon, namely, that a single
impression is conveyed to  the sensorium, though each eye re-
ceives the impression.   Whether this mode of accounting for
it be satisfactory or not, the  following facts are extremely in-
teresting,  and not sufficiently known, namely, that in  those
fishes whose eyes are  placed so completely on the side of the
head that the rays of  light from  any given object cannot im-
pinge on both retinae, as, for instance, in the cod  and  had-
dock, the optic nerves, instead of forming any union or com-
missure,  cross each  other  completely, having a membrane 
                         APPENDIX.                    gj ]

 interposed between them : in those fishes, again, whose  eyes
 are situated so that even a small  portion of their retinas cor-
 respond, as in the carp, we find  a few commissural fibres;
 and in those whose retinas correspond in every point, as in the
 skate, we find the commissure as  complete as in the  human
 being." — Solly on the Brain, p. 243.

                     Page 220, Line 2.
   No less than seven bones enter  into  the formation of the
 orbit; superiorly,  the frontal and sphenoid; externally, the
 same, with the malar;  inferiorly,  the  palate,  superior maxil-
 lary, and malar;  internally, the frontal, superior maxillary,
 sphenoid, ethmoid and lachrymal.

                         Page 232.
   It is rather too late to  discuss the question  whether phre-
 nology be true or false,  the researches of M. Flourens in many
 cases support the doctrine.  Much  confusion has been no
 doubt caused by considering the  brain  as the cause rather
 than the instrument:  by regarding the brain as the mind, and
 not as the agent through which the mind acts.

                     Page 237, Line 25.
   The theory that muscular contraction  is  due to electric cur-
 rents has been long held  in high  estimation by the German
 physiologists; the following rough translation  from a work by
 Joh. Christian Heinroth  upon Anthropologie,  Leipzig, 1822,
 embraces the most important points.
   "As the charging of  the nerves was considered an electric
 act, so also the discharging of the muscles;  the nerves were
 to convey sensation, but the muscles motion.   The manifest-
 ation of motion by the muscles is one of the deepest myste-
ries of nature, as mysterious as that of sensation by the nerves.
With the speed  of lightning is  the muscle put  in action,  a
proof of the electric nature of the motion ; it  is no mechani- 
312
APPENDIX.
 cal, but  a higher power, active  in  the  muscles.  The latter
 merely convey the expansive, or motor power;  they are, as it
 were,  permeated by this power; an electric stream courses
 through  them.  The most wonderful is their harmonious mo-
 tion ; the muscles are moved in groups — a proof that the im-
 pulse to  motion arises from a single point and is dispersed like
 rays to the various muscles.  This One-dom  point cannot ex-
 ist in the muscles themselves, it must be in the exciting organs,
 the nerves.   The charged nerve sends the electric stream  to
 the muscles,  which discharge themselves in  groups  in swift
 succession and with many regular, sometimes rectilinear,  at
 others curvilinear motions."

                        Page 244.
   The following curious experiment by Dr. Hunter, illustrates
 most clearly  the manner of growth in the bone.
   "I took a pig of a very large breed when young, bored two
 holes in the tibia, and put a shot  into each, measuring on  a
 card the  distance of  each from the other.  I allowed this pig
 to grow up to its full size, then killed it and took out the bone,
 and I found the two  holes at exactly the same distance from
 one another as at first.  Now if the bone had grown  in all its
 parts these two shot would have been removed  to a  distance
 from each other proportionate to the growth of the bone."
   Therefore,  " bones do not  grow  by having new particles put
 into the interstices of previously formed parts, so as to remove
 these to a greater distance from each other, by which means
 they should grow larger, — as, for instance, if I put a sponge
 into water, the water getting into all the  interstices makes  it
 larger, — but they grow by the addition  of new bone  on the
 external surface." — Hunter's Prin. of Surg. p.  48.

                    Page 280, Line 29.
  In most cases of attempted suicide the opening is  made so
high up as to defeat the  object, and almost without affecting
 the voice.
 
       VALUABLE     WORKS
                               RECENTLY
                 PUBUSHED, IN PRESS, AND FOR SALE
                                    BY
CHARLES  C.  LITTLE  AND  JAMES BROWN,
        BOOKSELLERS, IMPORTERS, AND  PUBLISHERS,
                NO.  112  WASHINGTON STREET...BOSTON.
January,  1841.
SSoofes  lately  3|utoltjslje&.
 HISTORY OF  THE  UNITED  STATES  FROM  THE DISCOVERY  OF
   THE AMERICAN CONTINENT.  In 3 volumes.   By George Bancroft.
   The First Part of this work, embracing the History of the Colonization of
 the United States, is now completed.  It forms three volumes 8vo,  and contains
 the account not only of the settlement of the thirteen original states, but of the Span-
 ish settlements in Florida, and of the  French discovery and colonization of Mich-
 igan and Wisconsin ;  the  discovery of the Mississippi, the colonization of Illinois
 and Indiana, of Mississippi and Louisiana, and  the  attempts at colonizing Texas
 by La Salle.   The  topics most interesting to the people of the great  valley of the
 Mississippi  are  delineated  more fully  than in any  American work, and from
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   The book is printed in  the best style, equal to that of the London  press, and is
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 Winthrops, of Smith, of William Penn, and Franklin, fac-similes of the first maps
 of the valley of the Mississippi, and of Lake Superior, with sketches illustrating
 Indian life  and appearance.
   This work has been favorably noticed in some of the best  journals  of Germany
 and England, and in the chief American periodicals.
  " We know i'ew modern historic works, in which the author has reached so high an
 elevation at once as an  historical inquirer and an historical writer.  The great conscien-
 tiousness with which he refers to his authorities and his careful criticism, give the most
 decisive proofs of his comprehensive studies.  He has founded his narrative on contem-
 porary documents, yet without neglecting works of later times and of  other countries
 His narrative is every where worthy of the subject.  The reader is always instructed,
 often  more  deeply interested  than by novels or romances.   The love of country is the
 Muse which inspires the author; but this inspiration is that of the severe historian.
 which  springs  from  the  heart."—Gotlingcn  Review, written by the  celebrated historical
 Professor Hekrf.n.
  "If any truth ever was 'stranger than fiction,'  it will  be found  in  this history; so
varied so vived, so heterogeneous, and yet so harmonious a picture do these early Amer-
ican annals  set before us ; so poetrcal  are they, though  at the same time so notoriously
and preeminently practical -in a word, as we began with saying', so picturesque. 
2                            LITTLE  AND  BROWN'S

©                                                                                    ©

     " Numberless illustrations of the truth of this general remark might easily be derived
  from Mr. Bancroft's pages.  He is poet enough to have clearly discerned and  fully ap-
  preciated the  splendid, poetical interest of his theme, and to  have given to  its various
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  neglect his business in his delight;  he only  avails himself of his excitement to do that
  business better ;  he uses his enthusiasm as a minister to  his industry.  We rejoice to find,
  meanwhile, that the work is appreciated in America as  we hope it will be in England."
                                                                   London Athenceum.

     " Mr. Bancroft, who is  an American himself, possesses the best qualities  of an historian.
  His diligent research, his earnest yet tolerant spirit,  and  the sustained  accuracy and
  dignity of his style, have been  nobly brought to bear upon one of the grandest subjects
  that ever engaged the study of the  philosopher, the legislator, or the historian.  There
  can be no doubt of his being possessed of the highest requisites of an historian."
                                                              London Monthly Review.

     " On the score of research, correct conception of the  beautiful in nature and in human
  character, and profound learning, united to copiousness and splendor of diction, this val-
  uable production is entitled to  the highest meed  of praise."—Canada Times, Dec. 1840.

     " A History of the United States, by an American writer, possesses a claim upon our
  attention of the strongest character.
     " It would  do so under any circumstances, but when we add that the  work of Mr.
  Bancroft is one of the ablest of the  class, which  has for years appeared  in the English
  language ; that it compares advantageously with the standard  British historians  ; that as
  far as it goes, it does such justice to its noble  subject, as to supersede the necessity of any
  future work of the same  kind ;  and if completed as commenced, will unquestionably for
  ever be regarded, both as an American and as  an  English classic."—Rcviczv in the North
  American, by  Gov. Everett.

     " The favorable notice  we took of Mr. Bancroft's labors on his first appearance  has been
  fully ratified  by his  countrymen.   His  colonial  history establishes his title to a place
  among the great historical writers of the age."—Review  in the North American, Jan. 1841.

     " We speak with confidence  when we  say Mr. Bancroft's persevering scrutiny of his-
  torical memoirs and documents, and  the  skilful use  he  has made of them, are calculated
  to give to his works, permanent and  universal value, as a classical history of  the United
  States."—Philadelphia American! Quarterly Rcvicic.

     " Gladly would we extend  these  extracts, but we have already exceeded  our  space.
  Most heartily do we  commend the  history to  our readers.   We commend it, especially
  to young men.  No more profitable  volumes can  they  study.  It should  not be the re-
  proach of any of their number  that they  are  ignorant of the past annals of their country.
  With such  attractive  volumes  as those of Mr.  Bancroft at command, no  excuse can be
  valid for  such neglect."—Boston Morning Post, 1840.

     " A good, and at the same time a  copious history  of  the United States.    Mr.  Bancroft
  has shown himself admirably qualified for the undertaking, by an easy and flowing style,
  patience  of research, and faithfulness of delineation."—New York Journal of Commerce.

     11 We consider it a source of congratulation to the whole  nation, that so accomplished
  a scholar, so  patient  an investigator, and so eloquent a  writer, has undertaken the much
  needed task of writing a worthy history  of these  United States.  In  the volume before
   us, we see abundant evidence that, while truth  will—at any expense of labor in  ferreting
   it out from the original authorities, instead of relying, as is so common, upon the  copies
  of copies—be fearlessly  spoken, no  prescription of time or  great  names  will be allowed
  to sanction error.     *    *     *    It will be  received, we feel well assured,  as a worthy
   offering to his country, from one of her  able and qualified sons."—New  York American.

     "These volumes  are eagerly sought and read.   The characteristics of Mr. Bancroft's
   history are, patient research, apt illustration, original and felicitous grouping of characters
   and events, and general impartiality.   His style is ornate and elaborate ; always  arresting
   and retaining attention."—Neio York American, Dec. 1840.

     " It is  a matter of question to us, if any history in the  language contains  more beau-
   tiful touches. A mine of wealth is  here opened  to the artists of our land;  and  we are
   much at  fault, if the beautiful sketches and touching outlines  of the author, are not soon
  transferred to the canvass.   Most  sincerely do  we trust, that these volumes maybe
   placed in all  our houses, and that our young  men  may  become intimately versed  in the |
   pages of this remarkable production."—New  York Commercial Advertiser, Jan. 1841.

©                                                                                     © 
QUARTERLY ADVERTISER.
     HISTORY  OF THE REIGN  OF  FERDINAND AND ISABELLA,   -

                THE CATHOLIC.   By  William H.  Trescott.

                      WITH SFLENEID PORTRAITS AND MAPS.

                         In 3 volumes 8vo.   7th edition.

  In this edition the publishers have added a Map for the  War of Grenada and for
Gonzalvo de Cordova's Campaigns in Italy.

  "The history of  Spain cannot boast of a more  useful and  admirable contribution since
the publication of the great work of Robertson."—British and Foreign liecieto.

  "Bold indeed it  is ; but in our judgment eminently successful.   On such works we
are content to rest  the literary reputation of the country."—North American Review.

  " In every page,  we have been reminded of that untiring patience and careful discrim-
ination,  which have given celebrity to the great,  though not always impartial,  historian
of the Decline and Fall of the Roman Empire."—Ncio York Review.

  " His  laborious  industry, conjoined  with native ability, places  the author next  to
Hallam, amongst our living historians, for the  largeness and  philosophical  justness of
his estimate, the distinctness and comprehension  of his general surveys, and the  inter-
esting fulness of his narrative."—London Spectator.

  " Mr. Prescott's is by much the first historical work which British  America has yet
produced, and one that need hardly fear a comparison  with any that has issued  from the
European press since this century began.—London Quarterly Rcvicio.

  " One of the most remarkable  historical compositions that have  appeared  for a long
time."—Bibliotheque Universelle de Geneve.

  " Mr.  Prescott's  merit chiefly  consists  in the skilful arrangement of his materials,  in
the spirit of philosophy which animates  the  work, and in a  clear and elegant style that
charms and interests the reader.   His book is one of the most  successful  historical  pro-
ductions of our  time.  The inhabitant of another world,  he  seems to have shaken off all
the prejudices of ours.  In a word, he has, in every respect  made a most valuable addi-
tion to our historical literature."—Edinburgh Review.
   THE WORKS OF  EDMUND BURKE, IN NINE VOLUMES, OCTAVO.

   " The present edition of Burke's works is more complete  than  any  one  which has
 hitherto appeared either in England or America.  It comprises the entire  contents of the
 English edition of his works in sixteen octavo volumes, including two volumes of speeches
 on the trial of Hastings, published in lt27, and which  have never before been republished
 in this country.   It also  contains  a reprint of the  work  entitled  ' An Account of the
 European Settlements in  America, first published in  1761,  which, though  published
 anonymously, is well  known to have been written by  Burke, and also the  correspondence
 with French  Laurence, which are  not  contained in the  English edition of his collected
 works.   Although the present edition contains a volume more than the latest and  best
 English one,  it is offered at less than one  half the price.   It has been the aim of the pub-
 lishers to present the work in a form and style worthy of its contents; and it is confidently
 offered to the favorable regard of the  public  from its completeness, its moderate price,
 and its typographical excellence."—Preface to the Edition.

  " The  publishers of this edition  have borne  in mind the nature and value of the con-
 tents, and given the mechanical execution a degree of excellence corresponding to the
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  " This edition of Burke  may be considered as containing all that that distinguished
 writer intended for the press, and is commended to the taste and judgment of those who
 are forming or completing a library.— United Slates (Philadelphia) Gazette.

  " Possessed of most  extensive knowledge, and of the most various  description ; ac-
 quainted alike with what  different classes of men knew, each  in his own province, and
 with much  that hardly any one ever thought of learning ;  he  could either  bring his
masses of information to  bear directly upon  the subjects to which they severally belong-
ed—or he could avail himself of them generally to strengthen  his faculties and enlarge 
4
LITTLE AND  BROWN'S
m
his views—or he could turn any portion of thetn to account for the purpose of illustrating
his theme, or enriching his  diction.   Hence, when  he is handling any one matter, we
perceive that we are conversing with a reasoneror teacher, to whom almost every  other
branch of knowledge is familiar.  His  views range over all cognate subjects ; his reason-
ings are derived from principles applicable to other matters as well as the one in hand ;
arguments  pour in  from all  sides, as well as those  which start  up under our  feet, the
natural growth of the path he is leading us over;  while to throw  light round our  steps,
and either explore its darker places, or serve for our  recreation, illustrations are fetched
from a thousand quarters ; and  an imagination marvellously quick to descry unthought
of resemblances, pours forth the stores, which a lore much more marvellous has gathered
from all ages, and nations, and arts, and tongues.  We are, in  respect to the argument,
reminded of Bacon's multifarious  knowledge, and  the exuberance of his learned fancy ;
while the many-lettered diction recalls to mind the  first of  English poets,  and his  im-
mortal verse, rich with the spoils  of all sciences and all times."
                                   Lord Brougham.—Sketches of English Statesmen.
THE POETICAL WORKS OF  EDMUND SPENSER, in 5  volumes,  12mo.,
  first American edition, with introductory observations on the Faery Queene, and
  notes by the Editor.
  A few copies beautifully printed on large paper, octavo.
  OCT3 Copies in fine binding for presents, &c.
  The character of this edition will be learnt by the letters and notices which follow:

                          From Professor Ticknor—Boston.
Messrs. Ltttle & Brown,
  Gentlemen.  Sir Walter Scott, in a Review of Todd's edition of Spenser,  written evi-
dently with kind feelings towards its editor, cannot help  saying, at the end  of it,  " We
conclude with a single hint.   Mr. Todd is a man of learning and research.   We wish he
would write essays in the Archaeologia and renounce editing out ancient poets."  Todd's
edition, however, is the only one that can come into competition with yours;  since, what
was done in the middle of the last century by Upton, Church, and Warton for the Faery
Qut-ene, and by Hughes for  the whole works of Spenser, is all used by Todd. There is
no doubt, therefore, you have published the best edition of Spenser yet known.  But you
have, I think, done more than this.  You have, it seems to  me, published a positively
good, useful, and agreeable edition of him ; one that will cause him  to be read and en-
joyed by many classes of persons, who would  otherwise not have  ventured  to open his
pages.  I have been in the habit of using Todd's  edition these twenty  years, and last
winter read in it all Spenser's poetry ; and as I have recently gone over nearly the whole
of your edition,  I feel as if I  could judge fairly of its value.  The result  is, a strong per-
suasion in my mind, that the talent and taste  shown in the beautiful  introductory obser-
vations of your accomplished editor, with the short, exact, and sufficient notes, glossorial
and explanatory, which  he has put at the bottom of each page, where they are wanted,
and not at the end of the work, where they would be almost useless, constitute this pub-
lication a real and  permanent service rendered to the cause of English literalure in this
country ; a service the more  important, as, while you have made your edition good, you
have also made it typographically .attractive, and yet so cheap that lew readers of  English
literature need to refuse themselves the pleasure of owning it.  I wish you  would  pub-
lish similar editions of Chaucer, and of the old  Ballads, and the other old poetry scattered
in the collections of Percy, Ritsnn, Evans, Scott. Hartshorne, &c.  Let me  add, that I
am happy to  believe there  is encouragement  for such undertakings among us; and that
the public begin to  buy good and tasteful editions of our great English poets, in  place of
the pretty " Annuals," as they are called, which are, in general,  only beautifully orna-
mented trash.
    Your obedient servant,                                      George Ticknor.

                     From the Author of Ferdinand and  Isabella.
Messrs. Little & Brown,
   Gentlemen.  I have examined the copy of Spenser which you have put into my hands,
and am very ready  to bear my testimony, for as much as it is worth, to the excellent man-
ner in which the edition has been prepared.   A good edition of this old bard is almost as
difficult as that of an  ancient  classic.  The poets of his age abound  in  such local and
temporary allusions, as are  most natural  in a  period, when the taste is less cultivated
than the imagination.  In addition to these, Spenser enveloped himself in metaphor and
allegory, of the most complicated kind, while  he affected a language, regarded  as anti-
quated even by his contemporaries.   Owing to these circumstances, he is, although the
most picturesque writer in the most picturesque age of English literature, less read than 
QUARTERLY  ADVERTISER.
many o-her poets, of inferior merit, some of whom, it may be added, have  known how
to cover up their own nakedness  with his  fine things, without  much risk of detection.
It was fortunate that the  business of ed.ting this poet in the popular form  which you
intended, should have been committed to a man, who combines, what is rare—scholarship,
with a quick  perception of the beautiful, and a good taste which has made him  more
anxious to show off h.s author than himself.   There is no pedantic parade of learning in
the notes, which  are directed to  instruct the  reader  in what is  obscure in the text, or to
point out its less obvious peculiarities   Every one will appreciate the value of this, who
has waded through the learned lu.nberof Spenser's preceding commentators, under whose
hands the flowers of poetry seem to wither, while  they are digging and delving after  the
roots from  which  they have sprung.  In addition to these excellent Notes the text is
further illumined by a glossary of the  obsolete words, judiciously placed at the bottom
of the  page, where it may be embraced at a single glance with the text, an arrangement
far  preferable to that of other editions,  where the glossary, from being removed'to  the
end of the  Canto, or the  volume, imposes a  task on  the reader, littleness burdensome
than that of working his way with a dictionary.  The " Introductory  observations to
the Faery  Queene" are a very valuable addition  to  the stores of literary criticism,  ex-
hibiting a nice  discrimination of  the characteristics of the poem, with a <n-nuine sensi-
bility to its extraordinary  beauties, which will not surprise those who are familiar with
the writings of the accomplished  Editor.   It is  needless to remark  on the excellence of
the typography and the mechanical execution of the  work, as they are obvious to all.   I
heartily wish it may find the patronage,  which so liberal an undertaking merits.
  Very truly, your obedient servant,                             Wm° H. Prescott.

  " Messrs. Little & Brown,  of Boston, have published, in five volumes,  the entire works
of Spenser, with a Biography of that eminent poet.   They have done full justice to  the
author in the handsome style in which they have caused  the  work to be  issued   We  are
glad to see this spir.t of liberality in  the publishers, and doubt not thiit it will  be  met by
a correspondent willingness on the part of  readers to  add slightly to the expense, in order
to insure good appearance."—United States  Gazette.

  " The appearance of a beautiful edition of Spenser, with an original introduction and
notes by an eminent editor is an event of no trifling importance in the annals of literature.
In the second  book of the Faery  Queene the poet cites the  wonders of the new discovered
Western World, as a proof that in describing  the  marvels of Fairy land he is  not  ex-
ceeding the bounds of possibility   Could he  have foreseen that in little more than two
centuries the verses he was penning, would be published, commented and lectured upon,
and  familiar  as household words in that newfound Atlantis, which seemed  to him fit to
be compared with the fabulous  Elfin kingdom, he would  perhaps  have been ready to
confess that all  the splendors which his boundless imagination had conjured up were to be
eclipsed by the amazing realities  which time was to bring into being.
  " A  grateful posterity has set up statues and storied monuments to the memory of  the
mighty dead ;  but we  regard  this tribute of  respect  and  admiration for  Spenser,  as  a
nobler monument of his worth than  the  marble which  Kssex  raised over  his grave in
Westminster Abbey.   The simple,  but dignified inscription  on  that marble infoims  the
reader that Spenser's ' divine  spirit needs no other  witness, than the  works he left behind
him.'  A monument has now been reared in a remote age and  in a distant world which
sacredly-verifies these  words.
  " An edition  like this has long  been a desideratum in our libraries ;  for we have hitherto
had  no other alternative  in reading Spenser, but to  use an edition with no notes at  all,
and no explanation  but a  glossary appended to the last  volume, or an edition so  encum-
bered and loaded down with notes and comments, that  a fortune would be  required to
purchase it, and a life-time to read it.  This want is supplied by the beautiful edition now
offered to the public.   The notes  are few, discreet and interesting, but sufficient to explain
the text; and the glossary is printed at the bottom  of each page just above the notes.
The difference between  reading with  these  aids, or reading  an edition  in which  ihe
glossary is printed at the end of the  last volume, is nearly as  great  as we find between
study'inff a  Latin or Greek author, with an  intelligible translation printed on  the  same
pace with the text, or searching for his  meaning by the help of a lexicon alone.
  "The  Introductory  Essay is an admirable critique, giving a comprehensive and satis-
factory view of  the  outline of the poem, its peculiar  beauties and  merits, the historical
references  and the nature of the  allegory.  It is  written in a  most  engaging style, and
displays a thorough acquaintance with the  poem, and with all that has been written  about
the poem   Without any  parade of learning the writer shows, in every line, that strength
which learning alone can give."—Boston Daily Advertiser.

  " We are glad to see that the old orthography is strictly preserved  throughout, though
we have heard  some good natured people remark, that they should  like to have  had  the
SDellinir a little modernized !  not reflecting that more than  half the flavor of the different
works  would have evaporated  in the process.  They would still have contained  much
© 
6                           LITTLE  AND  BROWN'S
©                                                                                 ©
  good poetry, but it  could hardly have been  called the poetry of Spenser, for such  a
  change would have  involved many others, still  more important.  We repeat,  that Mr.
  Hillard has discharged the duties which he undertook in a most excellent manner—credit-
  able at once to himself and useful to all his readers.  We must not omit to mention, that
  these volumes, in point of mechanical execution, are among the most elegant that have
  ever come from an American press.   They will bear a rigid comparison with  the most
  elaborately finished London productions "—Boston Morning Post.
     " We consider this reprint of Spenser, with the excellent annotations and other labors of
  the American editor, as an important step towards the more general introduction of works
  of this class.  It is remarked, properly, that the scholar will  find only familiar  matter in
  these volumes; but even such a reader will return to the Faerie Queene with renewed
  pleasure in the attractive  dress of  tasteful typography."—Philadelphia National  Gazette.
A  MANUAL OF  POLITICAL ETHICS,  DESIGNED CHIEFLY FOR  THE
  USE OF COLLEGES AND STUDENTS AT LAW ; PART  FIRST, CON-
  TAINING BOOK I. ETHICS GENERAL AND  POLITICAL ;  BOOK II.
  THE STATE.  By Francis Lieeer.   2 vols. 8vo.

  I beg leave to  say, without meaning any formal  compliment whatever, that your
Manual of Political Ethics is a profound work, full of deep reflection, solid principle, and
sound and apposite illustrations.   I have read it over superficially, but I  have begun and
have far advanced in the study of it with notes.  1 think your ethical and  political prin-
ciples just and admirable and most  instructive as to right, duties, property, social rela-
tions, government, sympathy, &c. &c, and I hope and intend to make myself familiar
with your work as a text book   Yours most truly,                    James Kent.

  " The work abounds with profound views of government, which are  illustrated with
various learning.  To me many of the thoughts are new, and as striking as they are new.
If I may be allowed to judge of the whole work from this specimen, I do not hesitate to
say that it constitutes one of the best theoretical treatises on the true nature and  objects
of government, which has been produced in modern times, containing much for instruc-
tion, much for admonition, and  much for  deep meditation, addressing itself to the wise
and virtuous of all countries. The work  has with  me a still greater  value, in that its
aim and end are practical." &c.—Extract from a letter of the Hon. Joseph  Story.
  *  *  *   u They are both (the State and Absolutism) subjects of deep importance, and
are treated in a new and very interesting manner.  With some, not important exceptions,
I am disposed to concur in the views which you take.
  " I hope you will present the work to the public at an early day.  It would be  quite
an acquisition to our literature, and do much to call public attention to subjects in which
all have so great an interest."—Extract from a letter of the Hon. John C. Calhoun.

  " The various mistakes occasioned by the habit of  seeking for  the origin of society in
the rudest conceivable condition of human existence,  falsely  denominated the  ' state of
nature' are treated in a masterly manner in the Second Book of the work before us."
  "Many other topics, discussed  with  ability and clearness and  enriched  with a great
variety of illustration, we cannot even refer to, without exceeding our limits.  We trust
that this work will be the means of calling the attention of our countrymen to a subject
in  which they of all others, ought to be well versed."—London Examiner.

  " Considering the systematic completeness with which the subject is handled, and the
manner in which the accidents of things are put aside and the essentials aimed at, if not
always reached, Political Ethics may be classed amongst the best treatises on Government
since the days of Aristotle."—London Spectator.
  LEGAL  AND  POLITICAL HERMENEUTICS,  OR PRINCIPLES OF IN-
     TERPRETATION AND CONSTRUCTION  TN  LAW  AND POLITICS,
     WITH  REMARKS ON  PRECEDENTS AND AUTHORITIES.   Enlarged
     edition.  12mo.  By Francis  Lieber.
     *»#«<[ regard the Hermeneutics as a work eminently useful to our profession—
  not merely useful to  students, but to men of long experience at the bar—as a most lucid
  exposition of the principles and admirable illustration of the science of interpretation and
  construction.  It is a valuable  contribution to the law.  I have given the Ethics only a
  cursory examination in MS. ; but from this rapid glance I am induced to believe, that  it
  is well .worthy the reputation of the author;  and I cannot but think that the public will


0                               ....                               © 
QUARTERLY  ADVERTISER.
regard the publication as a permanent addition to the sound and useful learning of the
day—destined, not like many other publications, to serve but for a day—but  rather to
incorporate itself into the more enduring fabric of solid  science."—Extract from a letter
of Mr. Greenleaf, Professor of Law at Cambridge.
DICTIONARY OF  LATIN SYNONYMES  FOR THE USE OF SCHOOLS
  AND PRIVATE  STUDENTS,  WITH A COMPLETE  INDEX.  By Lewis
  Ramshorn ; from the German, by Francis Lieber.  12mo.

  " We are glad to see, in our own language, a translation of this valuable work of an
eminent German scholar and practical instructer.  If the  Latin language is still to be a
part of our course of education,—and we hope it will long continue to be so,—it must
be studied with the aid of such works as the present; for which, indeed, we shall be
obliged, for some time, to»look to Germany, now at the head of the literature of all Europe.
  " We cannot but congratulate the students of the Latin language in this country upon
the publication of a work, which is superior to any one of the kind, that we are acquainted
with, in the English language;  and it  cannot fail to be considered a necessary part of the
apparatus of every student's library, as well as of every school where the Latin language
is taught.
  " We must not conclude our remarks upon this volume, without adverting to the extra-
ordinary care with which  it has been carried through the press; a consummation, not so
easy as most readers would imagine, in works where the variety of types and  languages
is apt  to mislead the  most lynx-eyed corrector, and in school-books, above  all others,
of the highest importance."—North American Revieio.


MECANIQUE CELESTE, by the Marquis  De la Place, translated by Na-
   thaniel Bowditch, L. L. D., to which is prefixed a Life of Dr. Bowditch, with
   Portraits, &c. &c.   Complete in 4 volumes, royal 4to.
  A few sets of this great  work, now recently completed, may be had  if applied
for soon.  As it never will be reprinted, Public Libraries and individuals, who may
wish to  possess it, will do well to send their orders without delay.
MEMOIR OF NATHANIEL  BOWDITCH, by his Son, Nathaniel Ingersoll
  Bowditch, originally prefixed to  the 4th volume of the Mecanique Celeste.  1
  volume 4to.  172 pages.   With plates;  splendidly printed.
A DISCOURSE ON THE LIFE AND  CHARACTER  OF  THE  HON. NA-
  THANIEL BOWDITCH, L. L. D., F. R. S., delivered in the Church on Church
  Green, Boston.  By Alexander Young.


THE FRENCH  REVOLUTION.   A HISTORY.   Vol.  I.—The  Bastille.
  Vol. II._The Constitution.   Vol. III.—The Guillotine.  By Thomas Car-
  lyle.  A new  edition,  corrected  and enlarged, in 3 vols.  12mo.  London and

  Boston.  1839.
  " Of all books this is most graphic.  It is a series of masterly outlines a la Rrtzch.  Oh
more  much more.  It is a whole Sistine Chapel of fresco a la Angelo, drawn with a bold
hand'in broad lights and deep shadows.  Yet again it is gallery upon gallery of portraits,
touched with the free grace of Vandyke, glowing with Titian's living dyes, and shining
and gloomed in  Rembrandt's golden haze.  And once more, let us say in our  attempt to
describe this unique production, it is a  seer's second sight of the past.  We speak of pro-
phetic vision.  This is a historic vision,  where events rise not as thin abstractions, but as
visible embodiments;  and the gho.sts of a buried generation pass before us, summoned to
react in silent pantomime their noisy Wfe."—Boston Quarterly  Review, Oct. 1838.
A  SYNOPSIS OF THE  BIRDS OF NORTH  AMERICA.  By John James
  Audubon,  F. R.  S. S. L. & E.  8vo. 
o                         LITTLE AND BROWN'S
®                                             —                          ©
  ORNITHOLOGICAL BIOGRAPHY, OR AN ACCOUNT OF THE HABITS
    OF THE BIRDS  OF  THE UNITED STATES  OF AMERICA;  ACCOM-
    PANIED-BY  DESCRIPTIONS OF THE  OBJECTS REPRESENTED IN
    THE WORK  ENTITLED  THE  BIRDS  OF  AMERICA,  AND INTER-
    SPERSED WITH DELINEATIONS OF  AMERICAN  SCENERY  AND
    MANNERS.  By  John James Audueux, F. R. S. S. L. & E.  5 vols. Roy-
    al 8vo.
A GRAMMAR OF THE ITALIAN LANGUAGE.  By Pietro Bachi, Instruct-
  er in Harvard University.   A new edition revised and  improved, with the addi-
  tion of Practical Exercises and numerous Illustrations, drawn from the Italian
  Classics.   "Una lingua deve  avere 1' uso per base 1' esempio  per consiglio, e la
 'ragione per guida."  Cesarolti.  1 vol.  12mo.

MEMOIR OF  THE LIFE  OF JOSIAH  QUINCY,  JUN. OF  MASSACHU-
  SETTS.  By his son,  Josiah  Quincy.
                   THE AMERICAN CONVEYANCER.
              By George T. Curtis, of the Boston Bar.  12mo.
  This work contains all the varieties of legal forms of conveyancing and certify-
ing, that may be useful to the practical or  the professional  man, in all parts of the
United States. It contains a complete system  of Forms and  Directions for appli-
cants  for Letters  Patent; for the organization of Corporations; for the formation
of joint stock companies:  and the copies intended for  the use of this common-
wealth embrace the entire system of Insolvency under the Act of April, 1838.  The
publishers believe that  to  both the lawyer and the layman it is a work of great
utility, avoiding many of the defects and improving upon many of  the excellencies
of the books of conveyancing heretofore in use in this country.

               LETTERS  ON BOSTON.  By E.  C. Wines.
  " This little volume is the best guide the stranger can put in  his pocket when he visits
Boston.  It. points out every object worthy of notice in Boston and its vicinity ; its schools
hoteis. places of public amusement, architecture, libraries, with Letters on Mount Auburn,
Cambridge, &c.; interspersed with lively and judicious criticism by a gentleman whose
larger works have placed him amongst the most popular writers of the country."
                                                        Literary Telegraph.

THE INVENTOR'S GUIDE.  COMPRISING THE  RULES,  FORMS,  AND
  PROCEEDINGS,  FOR  SECURING  PATENT RIGHTS.   By Willard
  Phillips.   12rno.
  This Treatise embraces the laws and decisions, and principles and forms, that
were  considered to be of practical  importance to Inventors and Patentees; omit-
ting the legal proceedings and such other  matters as were thought to be peculiarly
useful to members of the profession of the law.
            DRAMAS, DISCOURSES, AND OTHER PIECES,
                  By James A. Hillhouse.   2 vols. 16mo.
  "About fifteen or twenty years ago, Mr. Hillhouse was well known  as the author of
Percy's Masque, Hadad and other Poems, which gave proof  of as much poetical talent,
as the country  had exhibited, and placed him in  the small  number of its favorite and
most favored authors.  Hut Mr. Hillhouse printed  his own works in his own way; and
though they were speedily taken from the market by eager admirers, he neglected or re-
fused to permit further editions of them to be published, until, for many  years past, they 
                       QUARTERLY ADVERTISER.                      9

©                                              ---              -=©
  have become absolute rarities.   At last he has suffered them to appear again, adding to
  Hadad and Percy's Masque, Demetria, a tragedy of great beauty and power; and making
  a second volume of three prose Discourses, the  Poem of Judgment, and the Sachem's
  Wood.  It is long since so graceful and so truly poetical an addition has been made to the
  body of our literature. The style of their execution, too, is suited to their character   We
  count upon them, therefore, to do us credit in all respects, at home and abroad, for there
  is a finish about the poetry and graceful elegance thrown round its power, that are rare
  in any country."—Boston Daily Advertiser.

    " Mr. Hillhouse is  known to be one of the best  writers of our country.  There is a
  smoothness and finish about his productions, which we do not. often see surpassed.  Some
  of the Discourses are upon subjects of interest, which are treated with force and  perspi-
  cuity."—Boston Morning Post.

  SALLUST'S  HISTORIES  OF THE CONSPIRACY OF CATILINE  AND
    THE JUGURTHINE WAR.  FROM THE  TEXT OF GERLACH, WITH
    ENGLISH NOTES.  Edited by Henry R.  Cleveland, A. M., late of  the
    Boston Latin School.  Stereotype edition. 12mo.

    " The best and cheapest Edition of Sallust for Schools."
ORATIONS AND SPEECHES, ON  VARIOUS OCCASIONS.  By Edward
  Everett.  1 vol. Octavo.
A CONCISE APPLICATION  OF  THE  PRINCIPLES  OF  STRUCTURAL
  BOTANY  TO HORTICULTURE,  CHIEFLY EXTRACTED FROM THE
  WORKS OF LINDLEY, KNIGHT,  HERBERT, AND OTHERS,  WITH
  ADDITIONS  AND  ADAPTATIONS  TO  THIS CLIMATE.   By  J.  E.
  Teschemacher.  Boston, 16mo.
 " Every person engaged in Horticulture or Agriculture will find this little work a rich
treasure."
THE TRIAL  OF JESUS BEFORE  CAIPHAS AND  PILATE.   BEING A
  REFUTATION OF MR.  SALVADOR'S  CHAPTER, ENTITLED  "THE
  TRIAL AND CONDEMNATION OF  JESUS."  By M. Dupin, Advocate and
  Doctor of Law.
     " If thou let this man go thou artjiot Cassar's friend."—John six. 12.
  Translated from the French, by a Member of the American Bar.  Boston, 16mo.
  THE HISTORY OF NEW  ENGLAND  FROM  1630 TO 1649.  By John
    Winthrop, Esq., first Governor of the Colony of the Massachusetts Bay.  From
    his original manuscripts.  With Notes to Illustrate the Civil and Ecclesiastical
    Concerns, the Geography, Settlement, and Institutions of the Country, and the
    Lives and Manners of the principal  Planters.  By James Savage.  2 vols. 8vo.

  A NEW AND COPIOUS LEXICON OF THE LATIN LANGUAGE; COM-
    PILED  CHIEFLY FROM THE MAGNUM  TOTiUS LATINITATIS LEX-
    ICON  OF  FACCIOLATI  AND  FORCE LLINI,   AND THE GERMAN
    WORKS OF SCHELLER AND LUENEMANN.   Edited by F. P. Lever-
    ett.  Royal 8vo.

  PASSAGES IN  FOREIGN TRAVEL.  By Isaac Appleton Jewett.  2 vols.
    12mo.

  COLLECTIONS  OF  THE MASSACHUSETTS HISTORICAL  SOCIETY.
'   Complete.   27  volumes, 8vo. 
10                      LITTLE AND  BROWN'S

©---------©



  PRINCIPLES  OF  THE  THEORY AND  PRACTICE  OF  MEDICINE.  By
    Marshall Hall, M. D.  First American edition, revised and much enlarged, by
    Jacob Bigelow, M. D.,  and 0. W. Holmes, M. D.  724 pages, 8vo.

    This English work, by an author of great  celebrity, has been revised and aug-
  mented with new matter adapting it to the present state of Medical Science, by
  the American  editors.  It  appears from the  advertisement that one  third of the
  entire volume  is written by the editors.  The following are some of the opinions
  of the American press in regard to this Edition.
    " We would unhesitatingly pronounce it the best and most complete text book for the
  study and practice of  medicine.  It is full of facts, well arranged  and digested, and free
  from the endless repetitions  and diffuse, ill digested  matter which are often introduced
  into treatises upon medicine.   The present state of the science is reached in almost every
  instance."—Philadelphia Medical Examiner.
    " In our next number we shall give a review of this work ; in the mean time we may
  commend it to the notice of the profession.   The additions by the American editors, are
  numerous and important."—Philadelphia American Journal of Medical Science.
    " It strikes us, after a patient examination, that no practitioner who has once had this
  book in his possession would know how to dispense without it.  The editors, or in fact
  authors, appear  to have wholly prepared the first part, a most excellent and indispensable
  addition to the  original text.  Throughout the entire  volume  the additions they have
  made are readily recognised, and form an  essential feature  in the construction of the
  American  edition.  To students of Medicine  especially we recommend this edition as
  being superior to any other work extant for them."—Boston Medical and Surgical Journal.

  A  TREATISE  ON  THE MEDICAL  JURISPRUDENCE  OF INSANITY.
                         By I. Ray,  M. D., 1 Vol.  8vo.
    " We have seldom engaged in the performance of a duty, either more agreeable in itself,
  or more gratifying to our pride of country, than that of making our readers acquainted
  with Dr. Ray's Treatise on  the Medical  Jurisprudence  of insanity ;  a  work, which,
  whether we regard it as a contribution to the cause of humanity, or as an attempt to em-
  body the results of moral science, in relation to mental disease and its incidents, is equally
  worthy of our admiration."  American Jurist.

  ANATOMICAL, PATHOLOGICAL AND THERAPEUTIC RESEARCHES
     UPON  THE  DISEASES  KNOWN  UNDER  THE NAME  OF GASTRO-
     ENTERITE, PUTRID, ADYNAMIC, ATAXIC, OR TYPHOID FEVER,
     ETC.,  COMPARED  WITH THE MOST COMMON ACUTE  DISEASES.
     By P. Ch.  A.  Louis.   Translated from the original French  by Henry I. Bow-
     ditch, M. D.  2 vols. 8vo.

   PATHOLOGICAL  RESEARCHES ON PHTHISIS.   By P.  Ch. A. Louis.
     Translated  from  the French, with Introduction, Notes, Additions,  and an Essay
     on Treatment.  By Charles Cowan, M. D.   Revised and altered by Henry I.
     Bowditch,  M.  D.  8vo.

   RESEARCHES  ON THE EFFECTS  OF BLOODLETTING IN SOME IN-
     FLAMMATORY DISEASES, AND  ON  THE INFLUENCE  OF  TAR-
     TARIZED  ANTIMONY AND VESICATION IN PNEUMONITIS.  By. P.
     Ch.  A. Louis.  Translated by C.  G.  Putnam, M.  D.   With Preface  and Ap-
     pendix by James  Jackson,  M.  D.  8vo.

  ANATOMICAL, PATHOLOGICAL AND THERAPEUTIC RESEARCHES
     ON  THE YELLOW FEVER OF GIBRALTAR OF 1828.  By P. Ch. A.
     Louis.   From Observations taken by himself  and M.  Trousseau, as members
     of the French Commission at Gibraltar.  Translated from  the manuscript by G.
     C. Shattuck. Jr. M. D.  8vo. 
QUARTERLY ADVERTISER.                      H
     PUBLISHED BY C. C. LITTLE AND  JAMES BROWN.


                        [CT3 Law Libraries purchased.


Abbott (Charles, Ld. Tenterden.)  Treatise of the  Law relative to Merchant
  Ships and Seamen.  4th Am.  from  the 5th Lond.  ed.  by John Henry Abbott,
  with Annotations by Joseph Story, and  an Appendix  containing the American
  Acts respecting the Registry and Navigation of Ships, &c.  8vo.
American Jurist and Law Magazine.   Svo.  Quarterly, $5 per ann.
Angell (Joseph K.)  Treatise on the  Right of Property in  Tide Waters.   With
  an Appendix, containing the principal adjudged Cases.  8vo.  New ed. prepar-
  ing for the press.
Angell (Joseph K.)  Treatise on the  Limitation of Actions at Law and Suits in
  Equity.  With an Appendix containing an abstract  of the Statutes of Limita-
  tions in the several States, Brook's  Reading upon the Statute of Henry VIII.,
  &c.  8vo.
Angell (Joseph K.)  Law Intelligencer and Review.  3 vols. 8vo.
Angell (Joseph K.) on Adverse Enjoyment.  8vo.
Angell (Joseph K.)  A Practical Summary of  the Law of Assignment.  12mo.
Angell (Joseph K.) and Ames (Samuel.)  Treatise on the Law of Private Cor-
  porations Aggregate.   8vo.  New ed. in preparation for the press.
Angell on Water Courses, new ed.  8vo.
BAYLEY^(Sir John.)  Summary of the Law of Bills of Exchange, Cash Bills, and
  Promissory Notes; from the 4th Lond. ed., with Notes by Willard  Phillips and
  Samuel E. Sewall.  2d ed.  8vo.
Barbour and Harrington's Equity Digest.   3 vols.
Chitty on Pleadings.   3 vols.
Chitty on Criminal Law.  3 vols.
Chitty on Bills.  8vo.
Chitty on Contracts.   Svo.
Curtis (George Ticknor.)  A Digest of Cases Adjudged  in the  Courts of Admi-
  ralty of the United States, and  in the High Court  of Admiralty in England ;
  together with some Topics from the works of Sir Leoline Jenkins, Kt. Judge of
  the Admiralty, in the reign of Charles II.   8vo.
Curtis's American Conveyancer.  12mo.
Cushing (L. S.)   Treatise on  the Contract of Sale, by  R.J. Pothier.   Translated
  from the French.   8vo.
Davis (Daniel.)  Civil and Criminal Justice.  Svo.
Davis.  Precedents of Indictments.  8vo.
Debates in the Congress of the United States on the bill for repealing the Law for
  the Organization of the Courts of the United  States, with the yeas and  nays,
  &c.  Svo.
Gallison's Reports.  Vol. 2d.
Greenleaf (Simon.)  Reports of Cases  in  the  Supreme  Court of Maine,  from
  1820 to 1831.  9 vols. 8vo.
Hilliard  (Francis.)  An  Abridgment of the American Law of  Real Property.
  2 vols.  8vo.
Hobart (Sir Henry.)   Rep. Temp. Eliz. et Jac.  I.,  reviewed  and corrected  by
  Edward Chilton.  1st Am. from the 5th Eng. ed.   With Notes by  J. M. Wil-
  liams.   8vo.
Hughes on Insurance.   1 vol. 8vo.
Howe (Samuel.)  Practice in  Civil Actions and Proceedings at Law in Massachu-
  setts.   8vo.
Jackson (Charles.)  Treatise on the Pleadings aud Practice in Real Actions, with
  Precedents of Pleadings.  8vo.                                      -
Journal of the Convention for framing a Constitution  of Government for Massa-
  chusetts from the  Commencement of their first session, Sept. 1, 1779, to the
  close of their last session, June 16, 1780, including a list  of Members.  Published
  by order of the Legislature.   8vo. 
12                        LITTLE  AND BROWN'S
m                                                                             ®
  Kent (James.)  Commentaries on American Law.  4 vols.  Svo.  4th edition.
  Mason (William P.)  Reports of Cases in the  Circuit  Court of the United Slates
    for the First Circuit from 1816 to 1830.  5 vols. 8vo.
    " These Reports comprise the Decisions of Mr. Justice Story on  the First Circuit of
  the LTnited States, and foljow in order after Mr. Gallison's Reports.  The decisions relate
  to a great variety of subjects—Constitutional, Admiralty, Personal  and Real  Law, and
  Chancery, and are characterized by the profound learning, acuteness and thoroughness of
  research, which are such eminent traits  of  their  author.   They will bear a favorable
  comparison, in  point of Learning and practical utility, with the best volumes of the Eng-
  lish Reports."
  Massachusetts Reports.   Tyng's Reports of cases in the  Supreme  Judicial
    Court of Massachusetts, from 1804 to 1822.   (Vol.  1st  by Ephraim Williams.)
    17 vols. Svo.
    " These Reports embrace the Decisions of the Supreme  Court of Massachusetts from
  the time in which they first began to be published  until  Mr. Pickering commenced his
  labors as Reporter.  During a portion of this  period Chief Justice Parsons, whose char-
  acter for learning and ability has been so widely diffused,  presided  on the  bench.  No
  Reports have sustained a higher reputation throughout the country  than these, or have
  been more extensively cited.  The greater part of the present volumes have been sterec-
  typed, and have been enriched by the learned Annotations of  Benjamin Rand, Esq , of
  the Boston Bar."
  Maule  (George,) and  Selwyn (William.)  Reports of  Cases in  King's Bench,
    containing Cases of Hilary, Easter and Trinity Terms 1S13; Michaelmas, Hilary,
    and Easter Terms 1813-14, and Trin. Mich, and Hil.  Terms 1814-15.  In the
    53d, 54th, and 55th years of Geo.  3d. Edited by Theron Metcalf, in 2 vols. Svo.
  Phillips (Willard )  On the Law of Patents.  8vo.
  Phillips on Insurance.  2 vols. Svo.   New ed.
  Pickering (Octavius.)   Reports of Cases in the Supreme Judicial Court of Massa-
    chusetts, from 1S22 to 1836.  21 vols. 8vo.
  Rand (Benjamin.)  A Treatise on the  Law Relative to Sales of Personal Property.
    By George Long, Esq.  Second American  Edition, with Additions.   8vo.
  Sumner (Charles.)  Reports of Cases  argued and determined in the Circuit Court
    of the United States for the First Circuit.  3  vols. Svo.
  Stansbury (Arthur J.)   Report of the Trial of Judge  James  H. Peck, on an Im-
    peachment by the House of Representatives of the United States.  8vo.
    " This volume contains a great amount of  learning  in regard to  contempts of court,
  libels, and impeachments, subjects upon which the counsel on both  sides  exhibit  proofs
  of very diligent research.  It  will be a valuable repository  of authority and argument,
  in future cases in which the right of courts to punish for contempts may be brought in
  question."
  Stevens (Robert,) and  Benecke (William.)   Treatise on Average and Adjust-
    ments of  Losses in Marine Insurance ;  with  Notes by Willard Phillips.  8vo.
  Story (Joseph.)   Selection of  Pleadings  in Civil Actions, with Annotations.  2d
    ed., with Additions by Benjamin L.  Oliver.  Svo.
  Story (Joseph.)  Commentaries on the Law of Bailments, with Illustrations from
    the Civil and the Foreign Law. 8vo.
  Story (Joseph.)  Commentaries on the Constitution of the United States, with a
    Preliminary  Review of  the Constitutional History of the Colonies and States be-
    fore the Adoption of the Constitution.   3 vols. Svo.
  Story (Joseph.)  The Same, abridged by the Author.   8vo.
  Story (Joseph.)  Commentaries on the Conflict of Laws,  Foreign and Domestic.
    2d ed., much enlarged.
  Story (Joseph.)  Commentaries on Equity Jurisprudence as administered in Eng-
    land and America.  2 vols. 8vo.   2d ed., enlarged.
  Story (Joseph.)  Commentaries on Pleadings  in Equity in  England and America.
    By Joseph Story, L. L. D., Dane Professor of Law in Harvard  University. 2d ed.
  Story (Joseph.)  Commentaries on the Law of Agency,  as  a  Branch of Com-
    mercial  and Maritime Jurisprudence,   with occasional  Illustrations from the
    Civil and Foreign Law.   Svo.
    The Early English Reporters ; valuable Works on the Civil Law; Reports
  of the several  States, and the most extensive collection of Law Books to be found
  in the United States.

©   ■         .........•""■""   -■-—t      "—■         "-"© 
QUARTERLY  ADVERTISER.
13
SEotts  3Jttst  Dtt&liBfjtS,
COMMENTARIES ON THE CONFLICT OF LAWS, Foreign  and Domestic,
  in Regard to CONTRACTS,  RIGHTS, and REMEDIES, and especially in
  regard to MARRIAGES, DIVORCES, WILLS, SUCCESSIONS, and JUDG-
  MENTS.   By Joseph Story, L. L. D., Dane Professor of Law in Harvard
  University.
  Second  Edition.   Revised, corrected, and greatly enlarged,  pp.  1104.

  The following notice of this edition of the above  work, from an eminent jurist,
has been received by the publishers.

  " It is superfluous to call the attention of the profession to '• this remarkable work,' as
it is styled  by the French reviewers, who justly predicted that it would 'e.xcite the most
lively interest in both hemispheres.'  The learned author is the first  in our day who has
in the fullest sense, employed  himself, ex professo, on  International Law ; producing a
work, styled, by Mr.  Justice Fergusson, of Scotland, 'the most comprehensive and can-
did in our language, relating to that department of the law.'  Its republication in Eno-land
and on the Continent, in several languages, is the best testimonial of the  sense entertain-
ed of its merits, by foreign  jurists ;  as the  rapid  sale of the first edition  is of its estima-
tion by the profession  at home.  To this second edition,  the  learned author  has added
nearly as much matter as was contained in the first;  availing  himself, with felicitous
energy and judgment, of all the sources of International Jurisprudence which  the dis-
cussions, occasioned by the appearance of  his work, have subsequently discovered ; and
leaving nothing to be  desired on this subject, either by  the practitioner or the statesman.
To our own country, composed as it is of a family of independent sovereignties, united
by the most intimate and frequent relations of trade, commerce,  and marriage, yet each
separate in its laws and jurisdiction, the work is invaluable,  The questions discussed in
it, particularly those relating to contracts,  remedies, administrations, and the laws of
inheritance and succession, are of daily occurrence ; and  no  American lawyer ought to
deem his library complete, where this Treatise is wanting."
REPORTS  OF  CASES  ARGUED  AND DETERMINED IN THE  CIRCUIT
  COURT OF THE UNITED STATES, FOR THE FIRST CIRCUIT.  By
  Charles  Sumner,  Esq.   Vol.  3.   Embracing the  Decisions of Mr.  Justice
  Story, from October Term 1837 to October Term 1839.
  A YEAR'S LIFE.   By James Russell Lowell.  1 vol. 16mo.
  " We take great pleasure in calling the attention of our readers to this volume of poems.
It bears the marks of real  poetical  power and of a highly cultivated power of composi-
tion.  It is a real relief in  the  midst of the  forced and hackney specimens of what is
called poetry with which our periodicals are crowded, to meet for once with a poet whose
inspiration is nature and  truth.   One reading does not satisfy ; we are delighted  by another
and another perusal, and cannot but take the mood of the author and go hand in hand
with him."—Boston Daily Advertiser.


LETTERS  OF MRS.  ADAMS,  THE  WIFE  OF JOHN  ADAMS,  WITH
  AN  INTRODUCTORY  MEMOIR.   By her  grandson,  Charles Frangis
  Adams.  2 vols. 16mo.  2d edition.
  " We cannot undertake to indicate the most attractive portions of what is throughout
highly entertaining, or instructive, or both. Now great people and events of the day are
brought before the view, and now modes of dress  and ceremony are sketched with a
distinctness, of which only the female hand is capable."
                                         Jtorth American Revicir for October 1840.

  " Tt will naturally be presumed that this correspondence of  an uncommonly sensible
woman like Mrs  Adams, who lived in an eventful period of our history, and was person-
ally  and for the most part intimately acquainted  with the great men of her times, must
be full of interest and instruction ; and so in fact it will be found to be by every reader."
                                             New York Review for January ld41. 
14                      LITTLE AND BROWN'S
m                                                                        ©
  OUTLINES OF ANATOMY AND  PHYSIOLOGY,  TRANSLATED  FROM
    THE  FRENCH OF M. MILNE  EDWARDS,  Doctor of Medicine,  Profes-
    sor of Natural History at the Royal  College of  Henry IV,  and at  the  Central
    School of Arts and Manufactures in Paris.   By J.  F. W. Lane, M.  D.  Boston :
    1 vol.  octavo, with finely executed Wood Cuts.

                                CONTENTS.
    Preliminary  Remarks; General Characters of Living Beings; General Char-
  acters of Animals;  The Functions of Animals and  their Organs; Organic Tis-
  sues; The  Functions  of Nutrition;  The Nutritive  Fluids, or the  Blood; Circu-
  lation of the Blood; Apparatus of Circulation in Man; Mechanism of  the Circula-
  tion; Absorption; Exhalation, and the Secretions; Transudation, or Sanguineous
  Effusion; Exhalation;  Secretions; Respiration; Apparatus of Respiration ; Me-
  chanism of  Respiration;  The Influence of Respiration upon the other Functions;
  Animal  Heat;   Digestion;  Urinary Secretion;  Review;  Functions of Relation;
  Nervous System;  Sensation;  The Sense of Touch;  The Sense of  Taste; The
  Sense of Smell; The  Sense of Hearing;  Light; The Intellectual and Instinctive
  Faculties; Motions; The Voice;  Functions of Reproduction.

  SKETCHES  OF  THE  JUDICIAL  HISTORY  OF  MASSACHUSETTS,
    FROM 1630  TO THE  REVOLUTION IN  1775.   By  Emory Washburn.
    1 volume. Octavo.
REPORTS  OF  CASES ARGUED  AND DETERMINED  IN  THE  SU-
  PREME  JUDICIAL COURT  OF MASSACHUSETTS.  By Octavius Pick-
  ering.   Vol. 18.  (Volumes 19 and 23  in preparation, which will complete Mr.
  Pickering's Reports.)

A NAVAL TEXT  BOOK, containing a series of Letters addressed to the Mid-
  shipmen of the United  States Navy, on Rigging, Equipping, and Managing Ves-
  sels.  A set of Tables for  Stationing in Watches, at Quarters, and for all Evo-
  lutions ;  the Officers and Crews  of all classes of Vessels of War.  A Naval
  Gun Exercise, with Plates, for Stationing at the Guns, and Exercising at Quar-
  ters ; the Officers  and Crews of all Vessels; aud a Dictionary of Sea Terms and
  Phrases.   1 vol. 8vo.
  " A work of this description, containing such a variety of matter, cannot but be
useful to all young seamen, in the merchant as well as the public service.  There
is not now any work to which a  young seaman can turn  to gain information in
his  profession except Falconer's Marine Dictionary."
A COLLECTION OF THE  PLANTS OF BOSTON AND ITS VICINITY,
  WITH THEIR GENERIC AND SPECIFIC CHARACTERS, PRINCIPAL
  SYNONYMS, DESCRIPTIONS, PLACES  AND GROWTH, AMD  TIME
  OF FLOWERING, AND OCCASIONAL REMARKS.  By Jacob Bigelow,
  M. D., Professor of Materia Medica, in Harvard University, Member  of  the
  Linnsean  Societies of London and Paris.   Third edition  enlarged, and contain-
  ing a Glossary of Botanical Terms.  1 vol. 16mo.


CHARLES  ELWOOD:  OR THE  INFIDEL  CONVERTED.   By  0.  A.
  Brownson, (Editor of the Boston Quarterly Review.)  1 vol. 12mo.
                         Extract from the Preface.
  " I have  embodied in it the  results of years of inquiry and reflection ; and I have
thought it not ill-adapted to the present state of the  public mind in this community.  It
deals with the weightiest problems of Philosophy and Theology, and perhaps some minds
may find it not altogether worthless." 
QUARTERLY  ADVERTISER.
                   WLovUti   in   jjtreas
                       OR IN ACTIVE PREPARATION,
      BY CHARLES  C. LITTLE  AND JAMES  BROWN.
                         Boston, January, 1841.
                                   I.
COMMENTARIES ON THE LAW  OF EVIDENCE.  By Simon Greenleaf,
  L.L. D., Royall Professor of Law in Harvard University. In  one volume, 8vo.
  This work is arranged in Three Parts.  The first will treat of  the nature, basis,
and general principles of Evidence; its general  divisions into  positive and pre-
sumptive ; the  theory and  doctrines of Presumptive evidence ;  and those things
which Courts will themselves take notice  of, without  proof.   The Second  Part
will treat of  the Objects of Evidence ;  the rules which govern its production ;
and the quantity of proof required ; including  the subjects of primary and second-
ary evidence, and of original evidence and  hearsay, together with  that of the
admissibility of parol evidence  to  contradict, vary, or explain  that which is in
writing.    The  Third Part  will treat of the  Instruments  of Evidence, whether
written  or oral;  including  the subject of witnesses, and the weight and force of
their testimony; with the province and duty of the jury.
                                   II.
COMMENTARIES  ON  THE LAW OF PARTNERSHIP,  by Joseph Story,
  L. L.  D., in the course of preparation for the press.
                                  III.
THE  RIGHTS, DUTIES.  AND OBLIGATIONS OF THE  OWNERS, MAS-
  TERS,  OFFICERS, AND MARINERS  OF SHIPS IN THE MERCHANT
  SERVICE.  By George  Ticknor Curtis.  1 vol. 8vo.
    " Messrs. Little & Brown,
  " Gentlemen—I  have read  through with great  care a large portion of a Treatise by
George T. Curtis, Esq. upon the Rights, Duties, and Obligations of the Owners, Masters,
Officers, and Mariners of Ships in the Merchant Service.  I think the work is written
with great  ability, accuracy, and learning; and if published  it will constitute by far the
most valuable Treatise now in existence on this highly important branch of law, and will
be worthy of extensive public patronage.
                     " I am very truly and respectfully yours,  Joseph Storv."
                                  IV.
A TREATISE ON THE LAW OF PRIVATE  CORPORATIONS.  By Joseph
  K. Angell.  8vo.   Second Edition.
                                   V.
A TREATISE ON THE RIGHT OF PROPERTY IN  TIDE WATERS. By
  Joseph K. Angell.  2d edition.  Revised, with a general alteration in the man-
  ner of treating the subject, and comprehending the English and American decis-
  ions made since the publication of the 1st edition.
                                  VI.
REPORTS OF CASES ARGUED AND DETERMINED  IN THE SUPREME
  JUDICIAL COURT OF  MASSACHUSETTS.  By Theron Metcalf, [Suc-
  cessor  to Pickering.]  Vol. 1, part 2, which completes the volume.
                                  VII.
REPORTS OF CASES ARGUED AND DETERMINED IN THE SUPREME
  JUDICIAL COURT OF MASSACHUSETTS.   By Octavius Pickering, Esq.
  Vol. 9.  Second Edition; with Notes and References, by J.  C. Perkins, Esq. 
l^                     QUARTERLY ADVERTISER.
©'                                  ^=^
II. On—                              vill.
     A DIGEST of the 17 vols. Massachusetts and 23 vols. Pickering's Reports, com-
   plete in one volume, octavo, will be published as soon as Mr. Pickering  prepares
   for the press the 19th and 23d volumes, now wanting to complete his Reports.
                                      IX.
   THE  OLD  CHRONICLES OF  PLYMOUTH  COLONY,  IN  NEW ENG-
     LAND,  now first collected from unpublished manuscripts,  and contempora-
     neous printed documents; illustrated with historical  and biographical Notes.
     By  the  Rev. Alexander Young, of Boston,  Member of  the  Massachusetts
     Historical Society.  With a head of Gov.  Edward Winslow, from an original
     portrait painted in 1651.
     The value and interest of this work will be greatly enhanced by  the fact that it
   will contain an authentic  narrative of the  origin and  settlement  of the Colony,
   written at  the time  by the first planters themselves.   Mr. Young has fortunately
   recovered the most important part of Gov. Bradford's lost history of the Plymouth
   peoj le, and has other documents written by Bradford and Winslow,  some of which
   have never been printed, and others are wholly unknown in this country.
     This work will be a prior document to Morton's New England's  Memorial, and
   will constitute  the beginning and foundation of our history. It will make an octavo
   volume of  450  pages or more.
                                      X.
   HISTORY OF THE COLONIZATION OF  THE UNITED STATES.  By
     George  Bancroft.  Abridged by the Author for School Libraries and  Schools.
     2 vols. 16mo.
     This Abridgment  is designed for the young.  Its object is to put within the reach
   of the  schools of the country a sufficiently full account of the settlement of every
   one of the  States.   This Abridgment contains not only the history  of the Coloni-
   zation of the Atlantic Slates, but of the French settlements  from  Canada to
   Louisiana.  The attempt has been  made to omit every thing  beyond the ready
   comprehension  of an intelligent class of scholars, and to furnish an exact, and if
   possible, an interesting continued narrative, suitable for a class-book in reading, or
   as a manual for instruction.
     The work is  adorned by illustrations, and will be published in  March, 1841.
                                      XI.
                   PREPARING FOR  THE PRESS.
     A CONTINUATION  OF THE HISTORY OF  THE UNITED STATES.
   By George Bancroft.  The three volumes  already  published complete the His-
   tory of the  Colonization.  This Second Part of Bancroft's History will contain the
   HISTORY OF THE  AMERICAN REVOLUTION, in 2 volumes, octavo, with
   rich illustrations.   This  division  of the work  will comprise the History of the
   Country from 1750 to the Peace of 1783.
                                      XII.
   BOSTON  JOURNAL OF NATURAL HISTORY;  containing Papers and Com-
     munications  read  before the  Boston Society  of Natural History  and published
     by their direction.   Vol. III.  No. 4 will be ready in May.

     \JC7" Constantly for sale, a large stock of the most valuable Foreign and Ameri-
   can  works.   Orders for  Books  will be promptly  executed from  London  and
   Paris by the steam packets. 
sLT 
 
 
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