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ANATOMY AND  PHYSIOLOGY
APPLIED TO THE
Preservation of fjealth,.
BY DR. JOSEPH BROWN WALKEK.
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         BOSTON:
JORDAN & CO. 121 WASHINGTON STREET.
    DOW AND JACKSON, PRINTERS.
           1844.

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PREFACE.
  Every medical man must have felt and lamented the ignorance
so generally prevalent, in regard to the simplest functions of the
animal system, and the consequent absence of judicious co-opera-
tion, in the care and cure  of the sick.   Let it not be said that
knowledge of this description is superfluous to the unprofessional
reader ; for society groans  under the  load of suffering produced
by causes susceptible of removal, but left in  operation in conse-
quence  of our unacquaintance with our  own  structures,  and of
different parts of the system to each other, and of the objects
which surround us.  It is a fact admitted by all  intelligent per-
sons, that most of the bodily sufferings endured by mankind are
penalties of violated physical  law, and as in the civil  code, so in
the economy of health, " ignorance of the law excuses no one."
  Although  nature  may not always inflict  the  penalty  imme-
diately on  the act of transgression, yet she keeps  a  most rigid
record of all violations  and delinquencies,  and  will sooner or
later bring the transgressor to a fearful reckoning.  It is not the
design of the  author here, to enter into a lengthy  discussion of
the  subjects  referred to ;  but  to present to the reader,  and
especially to  the young, some important facts and information
with regard to the laws which govern our being, which if carried
into practice  may prove useful to all who  may chance to receive
it, and also to present it  in a brief and comprehensive pamphlet
form, so that the limited means of none shall preclude its perusal.
                                                  J. B. W. 
ANATOMY  AND  PHYSIOLOGY.
  Anatomy is that branch of knowledge  which  investi-
gates whatever  enters into the composition of animated
beings; while Physiology, in its limited sense,explains the
uses of the various parts of the living body.  Both are di-
vided into Comparative and human,  the  former relating
to inferior animals, the latter  of course to man.   We
shall confine ourselves in this little work to  that which
relates to man.   When the  allwise Creator determined
on making  beings which  should be able to move from
place to place, he contrived for  them an  organization
different from that of beings which were  fixed; consider-
ed in this light, the animal frame is the most wonderful of
all organizations of machinery.  No production of art can
be compared with it for the multiplicity and nicety of its
evolutions, and yet all these are  executed  by muscular
power acting upon the bones, and changing their relative
positions.  The incalculable  variety of  movements re-
quired of man is the reason why the bones  composing the
skeleton are so numerous,  and each so  admirably con-
nected with the others by articulation.  The advantages
of this arrangement are no less obvious than  admirable.
Had the osseous framework consisted of one entire piece,
not only would  man have been incapable of motion, but
every external  shock would have been communicated un-
diminished to the whole system : whereas,  by the divis-
ion of parts, and by the interposition of the elastic carti-
lages and ligaments constituting the joints, free and ex- 
[4]
tensive motion is secured.  The fabric resulting from the
connection of all these  pieces in their natural order of
arrangement is called the Skeleton. The number of bones
in the human  skeleton is  about 250,  divided by  anato-
mists into those of the head, trunk and extremities.  The
bones of the cranium or skull are eight in number, viz :
the frontal or bone of forehead, twe parietal or wall bones,
one occipital or back  bone of the  head,  two temporal
bones situated  before  and above the  ears, one ethmoid
and one sphenoid bone  situated in the internal part of the
head ;  all of which surround and form a complete protec-
tion for the brain from all ordinary accidents, and also to
the organs of hearing, seeing smelling and tasting.  Pro-
tection  and not motion being the sole  object of its  con-
struction, the numerous bones of which it is composed are
joined to each  other,  not by movable joints  like other
bones, but by a kind of dovetailing, which combines the
solidity of continuous structure with the advantages which
their separation gives in facilitating growth, and prevent-
ing the extension to all the injuries inflicted on one.  The
bones of the  face are  fourteen in number; consisting of
two superior maxilary or upper jaw  bones, one  inferior
maxilary or  lower jaw bone, two malar or cheek bones,
and  several smaller bones which it would  be unintelligi-
ble to the general  reader to attempt to explain.  There
 are eight small bones belonging to the ears four on each,
side, one at the root of the tongue called the os hyoides,
and thirty-two  dentas or teeth.  The four front teeth in
each jaw are called the incisor or cutting teeth, the two
next on each side of the face in both jaws  the cuspidati or
sharp-pointed teeth, the two upper of which are vulgarly
called the eye teeth, and the  remaining  twenty the mo
lares or grinders.   Each tooth may be divided into two
parts, viz. its body, or that which appears above the gums
and its  fang, or root, which is fixed in the socket.  Every
tooth is composed  of its enamel,  its  internal or  bony
substance.   The enamel is  the  hard white substance
which surrounds the body of  the tooth.   When  broken
it appears fibrous or striaeted ; and all the striae are di-
rected from the circumference to the centre of the tooth. 
[5]
  This enamel is thickest on the  grinding  surface,  and
on the cutting edges or point of the tooth, becoming gra-
dually thinner as it approaches the neck, where it termi-
nates insensibly.   Each tooth has an inner cavity, which,
beginning by a small opening at the point of the fang, be-
comes larger, and terminates in the body of the tooth.—
The  cavity is supplied with blood-vessels and  nerves,
which pass through the small hole in the root.   In  old
people this  hole commonly closes, and the sensibility of
the tooth is destroyed.
  The teeth are likewise secured in  their  sockets  by  a
red substance called the gums, which every where covers
the alscolar  processes, and has as many perforations as
there are teeth.   The gums of infants, which perform the
office of teeth, have a hard ridge extending through their
whole length ;  but in old  people, who have lost  their
teeth, this ridge is wanting.  The teeth are subject to  a
variety of accidents and pains.   Odontalgia or toothache
is a disease of very common occurence.   It usually  at-
tacks the molares or grinders, reaching sometimes up to
the eyes, and sometimes back into the cavity of  the ear.
At the same time there is a manifest determination to  the
head, and a remarkable tension and inflation of the blood-
vessels takes place, not only in  the  parts  next  to  that
where the pain is seated, but over the whole head.  The
toothache is sometimes merely a rheumatic affection, aris-
ing from cold, but more frequently from a carious or rot-
ten tooth.   It is also a  symptom  of pregnancy, and takes
place in some  nervous disorders.  It may attack  persons
at  any period of  life, though it  is most common to  the
young.  Many empirical  remedies have been proposed
for the cure of this painful disease, but none have afford-
ed permanent relief.  When the affection is purely rheu-
matic, blistering behind the ear will  almost always  re-
move it; but when it proceeds from a defect in the tooth
the pain is much more obstinate.   The celebrated Boer-
haave is said  to have applied opium, oleum  caryophyli,
camphor, and alcohol upon cotton.  When the constitu-
tion has had some share in the  disease, the sulphate of
quinine has belh recommended, to be taken internally, on 
[6]
account of its tonic and anti-septic powers.  But very of-
ten all these will fail, and the  only  infallible cure  is to
draw the tooth.
  We next come to the bones of the body or trunk.  The
spine  or back  bone consists of twenty-four small  pieces,
termed vertebra, from the Latin  word veriere to turn, as
the body turns on  them as on a pivot.   Of  these, seven
are called cervical  vertebra,  belonging to the neck;
twelve dorsal vertibrae, connecting the ribs at the back ;
and five lumbar belonging to the  loins.   The base of the
column rests  on  the bone which connects the hip bones
on the back of the pelvis, called the sacrum, below which
is a small bone, the os  coccygis, named from its  resem-
blance to the cuckoo's bill, which teuninates below  what
is called the back bone.   The vertebra are firmly bound
to each other in such a way as to admit of flexion arid ex-
tension, and  a certain degree of rotation, while by their
solidity and firm attachment to each other, great strength
is secured.  Some conception of this  strength may be
formed, when we consider the enormous loads which some
athletic men are able to carry on their shoulders, or raise
in their hands, the whole weight  of which is necessarily
borne by the vertebra of the loins.  As  the space occu-
pied by the abdomen gives large  outward dimensions to
this region of the body, it is only upon reflection that  we
perceive that the whole force  exerted by the human frame
in its most strenuous efforts,  centres,  ultimately, in the
bony column of the  spine.  While the body of the verte-
bra affords support to the superincumbent parts, the.pro-
jecting ridge behind, and rugged processes at  the  sides,
combine with it to form a large tube or canal, extending
from  the top to the bottom of the column, in  which the
spinal marrow »s contained and protected.  Between each
of the vertebra a thick compressible cushion of cartilage
and ligament  is interposed, which serves  to  unite the
bones to each other, to diminish the shock in walking or
leaping, and of admitting a greater extent of motion than
if the bones were  in immediate contact.
   The ribs are twelve  in  number on each side, attached
by their heads to the spine, and  by their %ther (cartilag- 
[7]
inous) extremities to the sternum or breast bone  before.
The seven uppermost are called  true  ribs, because the
end of each is connected directly  with the sternum or
breast bone in front ; while the five lower are called false
ribs, because one or two are loose  at  one  end,  and the
cartilages of the others run  into each other instead of be-
ing separately prolonged  to the breast bone, that not ex-
tending so low as opposite the five  false  ribs.    The use
of the ribs is to form the cavity of the chest for the recep-
tion and protection  of the lungs, heart, and great blood-
vessels, and to assist in  breathing by  their  alternately
rising and falling, as this action enlarges and  diminishes
the size of the chest and the capacity of the lungs.  The
hip bones being connected before by  what  is called the
os pubis, and in the rear by the sacrum, form the pelvis
or basin,  for the  support of the viscera of the abdomen.
  The bones of the upper extremities are, the clavicle or
collar bone  ; the  scapular or shoulderblade  ; the humerus
or arm bone ; the radius and ulna  or bones of  the  fore-
arm ; and the small carpal and meta-carpal  bones  and
phalanges, forming the wrist hand  and fingers.
   The  scapula is the broad flat bone lying at the  upper
part of the back, familiarly known as the shoulder-blade,
and so troublesome to many young ladies by  its unhand-
some projection.  It serves to connect  the  arm  with the
trunk of the body, and gives origin to many of  the  mus-
cles by which the arm is put in motion.   The  clavicle or
collar bone extends from the breast bone outwards to the
scapula.  Its chief use is to prevent the arms from falling
forward in front of the body ; and  hence it is wanting in
the lower animals, whose superior  extremities are much
closer to each other than those of man.
  The humerus or upper bone of the  arm is adapted by
a kind of ball  and socket joint to  a corresponding surface
in the scapula, and hence enjoys  great latitude of motion,
and is somewhat liable  to  dislocation.   The radius and
ulna, constituting the fore-arm, are  connected with the
humerus by a hinge-like  joint, which  admits readily  of
flexion and extension, but not of rotation ; and as the ar-
ticulation is of a peculiar construction, it is rarely  dislo- 
[8]
cated.   The movements of pronation and  supination, or
turning round the hand, are  affected not  by the elbow-
joint, but by the radius moving upon the ulna, by means
of joints formed for this purpose.   The  carpus or  wrist
consists of eight small bones, connecting the hand to the
fore-arm, which are too complicated to admit of explana-
tion here.  The bones of the hand are five in  number,
which  are united with  those of the  fingers, of which  there
are  fourteen on each hand.   The  lower extremities con-
sist  of the  os femoris  or thigh bone, which is the largest
bone of the human body ; the patella or  knee-pan ; the
tibia and fibula or leg bones  ; and the  tarsal and meta-
tarsal  bones, and phalanges, composing  the ancle, foot,
and toes.
   The thigh-bone is connected to the body by  means of
a large round head, deeply sunk into  a  corresponding
hollow in the pelvis, thus combining  freedom of motion
with great  security.   The thigh may  be moved back-
wards and forwards as in walking ; and  also  outwards
 and inwards, as when sitting  on horseback  or  with the
 legs crossed.  The socket being mnch deeper  than that
 of the shoulder joint, the thigh-bone has  not  the  same
 range of motion as the the humerus, but has proportion-
 ably greater security.
   The patella or knee-pan is well known.  It is a  small
 bone constituting the  projection of the knee. It increas-
 es the power of the muscles which  extend the  leg, and
 protects the front of the  knee joint.  The tibia or shin
 bone is the principal bone of the  leg, and is the only one
 connected with that of the thigh.  Its lower end forms the
 projection of  the inner ancle.  The fibula is  the long
 slender bone at the outer side of  the leg, the lower end
 of which forms the outer ancle.  Thus the tibia and fibu-
 la,  together with the  ancle joint,  which, like that of the
 knee,  are almost limited to flexion and extension.
   The bones of the feet, twenty-six in  each,  display an
 admirable mechanism, but without plates any description
 of them would be unintelligible.
   Our present aim being practical utility, we shall  there-
 fore pass over these  details, and rather  lay before the 
[9]
reader several considerations of a more general and  di-
rectly useful nature.  And here I shall quote largely from
Dr. Combe : Bones consist  of two  kinds of substances,
those  of an animal and those of an earthly nature.  To
the former belongs every thing  connected with  the life
and growth of bones, and to the latter the hardness  and
power of resistance by which they are  characterized.—
The relative proportions of the animal and earthy consti-
tuents vary, however, according  the period  of  life.   In
infancy the animal  portion  greatly predominates, and,
consequently, the bones are at that age comparatively
soft, yielding and elastic.   In middle life  the proportions
are more equally balanced, and while the bones thereby
acquire great hardness  and solidity, they still  preserve
some elasticity.   In old age, on the contrary,  when the
earthy constituent predominate, they become dry, brittle,
and comparatively lifeless.
  A very important  purpose is served  by the different
proportions which the animal elements of bone  bear to
the earthy, at different ages.  In early youth, when much
strength is not wanted, as the body is not exposed  to  se-
vere efforts, but when a greater growth of bone is requir-
ed to complete the development  of the human  frame, the
animal or  living part of the bone is  observed to be pre-
dominant.   But. in middle life,  when growth is finished,
and when  nutrition is  required only to  repair waste, a
larger proportion of the solid  or earthy, and a smaller
proportion  of the vital  constituents becomes necessary.
In old age, again, when the  wants of the system are
reversed, and when positive diminution of existing mass-
es is required to put the  frame into harmony  with the
shrunk muscles  and feebler powers of life, the absorbent
vessels carry away  more  of  the vital  matter, leaving
chiefly the  earthy, which, being less susceptible of change,
requires scarcely any  support  from within  ; and hence
the brittle and compact hardness of bones, and their little
capability  of uniting when  fractures  happen  at an ad-
vanced period of life.  At birth, many of  the bones are,
properly speaking, of  a cartilaginous  nature.   As the
bones  increase in growth, the cartilage is removed by the 
[10]
absorbents, and its place supplied by a  kind of cellular
membrane, in  the  interstices of which the  earthy par-
ticles are deposited ;  the two  forming  by  their union,
a  homogeneous whole called bone.   Although it is to the
softer material  alone  that vital properties essentially be-
long, it is usual to speak of the life, the vessels, and the
nerves of bones, as if life belonged equally to the earthy
and animal portions.   This is correct enough in reality,
because the union betwen the earthy  and  animal tissues
is always the product of life ;  and  the parts thus united
are, to all intents and purposes, living parts.  To carry
on the processes of waste and renovation, by which every
living structure is distinguished, all  parts of the body are
provided, first, with arteries conveying to them red or
nutritive blood ; secondly, with exhalents, by which the
new matter is deposited, and which are believed to be the
minute terminations  of the arteries ; thirdly, with veins
by which the blood is  carried back  to the heart ; fourth-
ly, with absorbent  vessels, which take up and carry away
the waste particles to be thrown out of the system ; and,
lastly, with nerves  to supply all these vessels, and the or-
gans on which they are distributed, with  that  nervous
energy which is essential to their vitality and to their con-
nection with other  parts of the system.  The bones, in-
sensible as they may seem, possess  all these attributes of
living and organized parts.  They  are all provided  with
blood-vessels, nerves, and with exhaling  and absorbing
vessels ; and they  are  constantly undergoing the  same
process of decay and  renovation to which all other living
parts are subjected.
   That the bones are provided with blood-vessels is shown
by the fact ,tiiat anatomists are  able to trace these vessels
into their substance, and to inject those of a young  sub-
ject with wax,  so minutely as to make the bones appear of
a lively red  color.   That they are  provided also  with
nerves is evident, both from dissection and from the ef-
fects of injuries and disease.   A healthy bone  may be
cut or sawn across without causing  pain,  but  when the
bone is inflamed, the most excruciating  torture is felt.
   And as sensation is the exclusive attribute of the nerv- 
[11]
ous system, this fact alone would  authorize us  to  assert
their existence, even though nervous fibres could  not  be
traced entering the osseous substance. It may be thought
that bones are, in their very essence, so hard and durable
as to render any such  supply of nourishment and change
of parts altogether unnecessary.   But if we  look for a
moment to the  advantages consequent upon this order of
things we shall see abundant reason to abandon such  an
opinion.
  In a state of health the bones are  insensible  to  pain ;
and here, also, the most provident benevolence appears.
For surrounded, as they are, by the softer and more sen-
sitive parts, they afford them ample protection, while their
insensibility enables them to act, for  any length of time,
without weariness or pain.  But when a severe accident
occurs to break them or to destroy  their  texture, pain
then becomes their kindest  guardian, and  the  sure pro-
moter of their recovery.   In such circumstances, indeed,
nothing can be more  truly benevolent than pain.   It ac-
companies that inflammation and vascular activity,without
which the work of reunion of the broken part cannot be
accomplished ; and is  the means of securing the  repose
and quietude which are essential to the exact adaptation
of the parts to each other, and which can be effected on-
ly by causing  great pain  to follow even the slightest mo-
tion.
  Now, if this was not so, if pain did not guard the limb
from motion when the process of recovery was going on,
the union would be incessantly disturbed by every heed-
less and unavoidable start altering the relative position of
the parts.  This is frequently exemplified  in practice.—
Looking at these facts, it  is impossible not to admire the
wisdom and benevolence manifested in the  adaptation of
the structure of bones in  every particular to the circum-
stances and occurrences  of life.
  We have already seen, that besides a large portion of
earthy matter,  which give to them dryness and hardness,
bones contain a large quantity of animal matter, which is
essential  to  their  constitution.   In  early  life  this car- 
[12]
tilaginous or gristly matter, predominates, and the  bones
are consequently less heavy, more pliable  and elastic,
and possessed of greater vitality.  In old age, again, the
earthy  part  predominates, and with  it  fragility, and
a less degree of vitality.  It is from this difference that
bones broken in youth  reunite in much  less  time  than
their reunion is effected in advanced life.
  The practical application to be made of our knowledge
of the constitution of the bones, as parts of  our  animal
frame, and as  governed by the  ordinary organic  laws,
will now be obvious.   Their health we have seen  to de-
pend on their regular supply of nourishment by the blood-
vessels, on a due supply of nervous energy by the nerves,
and on a due balance  between the action  of the  nutri-
ment and absorbent or  removing vessels.  To the steady
observation of these conditions, therefore, we are required
to attend.
  It is a common fault  to consider the study of an  organ
or function  complete, when we have viewed it on all  its
sides as an  isolated part, with regarding its  external re-
lations as constituting an essential portion of its history.
Thus, although we examine the structure and  functions
of the heart, and see  that it is a muscle, and that its office
is to contract, our knowledge of it is imperfect if we do not
go still further, and see that blood is  the stimulant which
causes its contractible  power to act.   And,  in like  man-
ner with the eye, whose relations to light are as essential
a part to its constitution as the transparency  of its mem-
branes or the convexity of its lens.   Now, in the case of
the bones,  we are apt  describe their hardness, their mo-
bility, and other qualities,  without sufficiently adverting
to the fact that, being organs of  resistance arid motion,
the frequent and regular performance of motion and re-
sistance is as essential  to their well-being, as blood is to
the heart, air to the lungs, or light to  the  eyes.    And,
therefore, when that  condition is not fulfilled, the  bones
become  feeble, diseased, and  unfit for  their  functions,
just as the softer parts  of the body do.  In practice  it is
of the utmost importance to be fully aware of this fact.
  It is familiar to  the professional mind, that a part de- 
[13]
prived of that exercise or action which nature destined it
to fulfil, becomes weakened and diminished in size.   The
bones are the solid organs of motion ; and unless they be
duly exercised in effecting motion, they, like the muscles
which move them,  suffer and decay in virtue of that uni-
versal law which requires exercise as  the  condition  of
their well-being—as the stimulus necessary to  their ex-
istence.
  In early youth, in particular, when every part teems
with life and activity, and is almost hourly acquiring an
increase of dimensions, the nutrient system is  in  a  state
of unceasing and powerful action, and an abundant  sup-
ply of nourishing food is  indispensable to health.   Nature
points out this fact, in the keen and vigorous appetite and
strong powers of digestion which every healthy child uni-
formly manifests.   This  law  of exercise,  as influencing
nutrition and growth, is universal in  its application,
and applies to the osseous as much as to  any other  sys-
tem.  If the bones are duly exercised in their  functions
of administering to motion, then active nutrition goes on,
and they acquire dimensions, strength and solidity.   If
they are not  exercised, the stimulus required for the sup-
ply of blood to them becomes insufficient ; imperfect nu-
trition takes places ; and debility, softness, and unfitness
for their office follow in the train.  This cause of defect-
ive formation  is most  active and most commonly seen in
the  bones of the spine in growing girls, who are denied
free exercise in that part ; and the consequent weakness
in the bones  and cartilages, as well as in the muscles, is
a very frequent cause  of distortions in the  bones of young
people, which no subsequent care can remove.
  It must  be observed, however, that  defective nutrition
may arise from other causes than inadequate exercise ;
but, even then, the consequences attending it are analo-
gous in their nature.  Among the poorer classes of peo-
ple of our cities, it often arises from deficiency of whole-
some food, and from damp,  dark habitations ;  among the
rjch, from feeble digestion and  assimilating  powers, and
pampering  in diet ; and also  from  errors  in clothing,
neglect of sufficient ventilation, and due exposure to the 
[14]
open air. Rickets, softness of the bones, and white-swell-
ings are accordingly observed to be almost wholly confin-
ed to children belonging to one or other of these classes.
  In the regular  order of nature, the maturity and per-
fection of all organs and  functions are attained at the
precise  time at which each is required.   The  bones  of
the infant are soft, vascular,  full of life, and vigorous  in
growth  ; but having no energetic  motions to  perform,
they possess little power of solid resistance.   In accord-
ance with this condition of the bones, the muscles which
move them are small, gelatinous, imperfectly fibrous, and
little capable of powerful contraction.  If the bones had
been made  solid and  heavy, from the  beginning, they
would not only have been inert  and  cumbrous masses,
destitute of  muscles capable  of putting them in motion ;
but, possessing less vitality, they would not have grown
with the rapidity necessary to adapt  themselves to the
growth  of the other parts of  the system.  If, on the other
hand, powerful muscles had existed  from the  first, they
would have  served  only to twist  the  soft  and yielding
bones into irregular shapes.   Or, if both solid bones and
strong muscles had been given from  birth, then a  com-
plete power of locomotion would have been  the result,
which from  the absence of intellect, and of knowledge  of
the external world to direct it, would  have led to  inces-
sant evils, if not to  speedy destruction.   But  as things
are arranged, the most profound wisdom and  the  purest
benevolence show themselves in the beautiful adaptation
of all the parts and functions to each  other, and to one
common end.
   Knowledge of the bones and of their several conditions
at different  periods of  life, is not  without its  practical
uses.  Especially is such knowledge  useful in  the  treat-
ment and the care of children.   Some fond parents, dis-
regarding the fact that  the bones are  comparatively soft
and pliable  in infancy,  and in their haste to see the  little
objects walk without support, are often soliciting attempts
at standing  or walkiug, long before the bones have  ac-
quired sufficient  power of resistance, and the muscles
sufficient power of contraction, to compete with the laws 
[15]
 of gravitation.  The natural consequence is a curvature
 of the bone, which, yielding like an elastic stick, becomes
 curved under the  weight of the  body.   The two ends ap-
 proach nearer to each other than  they ought,  and, of
 course, the muscles become shorter on one side than  on
 the other.
  Thus we have breifly adverted to the several parts of
 the osseous system,  which we will term Osteology.
  We will now turn our attention to that  part of the sub-
 ject which will come within the province  of Physiology.
 We will first speak of digestion :
  The word digestion is derived from the Latin word di-
 gere to dissolve.   As used in Physiology, it  signifies the
 change that the food  undergoes  in the stomach, by which
 it is converted into chyme, of which the chyle  is  subse-
 quently formed as matter destined for the  reparation  of
 the animal economy.
  The apparatus by which it is accomplished is of a very
 complicated kind.   It is less  so in those animals  who
 live on substances similar to their bodies,  as in the  car-
 nivorous animals,  or those that feed on flesh, than in those
 that subsist on substances of a  dissimilar character, as
 in herbivorous animals or those  that live  on vegetables.
 Man can derive nourishmsnt from almost  every article of
 food,and on this account he has been called an omnivorous
 animal.  His  digestive apparatus is, therefore, less com-
 plex than that of the herbivorous animals, but  more  so
 than the strictly carnivorous ones.  The organs of diges-
 tion consists of the mouth and its appendages, the  stom-
 ach and the intestines.  The teeth perform an  important
 part in preparing food for the stomach,  and have already
 been explained.  The tongue also assists  in mastication
 or  chewing, by removing the food from one  part  of the
 mouth to the other, and forming it into  the most  conve-
 nient shape.   The tongue is a muscular organ  of great
 power.   The saliva is poured into the mouth by means of
three pairs of glands, and is an important  agent  in diges-
tion.  The largest of these glands are  called parotid,
from being situated about the ear.  The tube which con-
veys their secretion  to the mouth, passes through the mus- 
[16]
cle of the cheek, and has been called the duct of Steno,
from the anatomist who discovered  and described it.   It
is the gland which is the seat of the disease known by the
name of mumps.   The sub-maxillary glands are situated
under the  lower  jaw, and the sub-lingual under the
tongue.   It is computed that not less than eight ounces of
saliva are poured into the mouth at  every  full meal.   In
immediate connection with the mouth, and situated in the
posterior part of it, is the pharynx, so called,  which is the
commencement of the passage to the stomach.   It is  of
an irregular form,  being considerably larger  at its upper
than at its lower extremity.  Its continuation down to the
stomach  is called the oesophagus.   It is by means of the
pharynx  and oesophagus that the art of deglutition or swal-
lowing is effected.
   The stomach is  the largest organ of digestion.  It lies
directly across  the body, just  under the  diaphragm  or
midriff", the great muscle which separates the  chest from
the abdomen.   The  oesophagus or gullet enters it in the
upper part of the  left extremity, which  is much larger
than the right.
  The opening  into the stomach  is called the cardiac or-
ifice, from its being near the heart,  and the opening from
it into the intestines, the pyloric orifice, from its guarding
the entrance.   The stomach of  an adult, in its ordinary
state of distension,  is capable of holding about three pints ;
but being of an elastic nature is  susceptible of being dis-
tended to greater dimensions.  Hence  we see the impro-
priety of crowding the  stomach with unnatural and heter-
ogenous  substances, as many persons do, as though the
end for which they were created was to eat and devour,
instead of eating to answer the design of their being.   It
has been said by an  author,on diet,  that " nearly one half
of the diseases and deaths occurring during the first two
years of existence, are owing to  errors in diet."
   The power of digestion is limited  to the  amount of gas-
tric juice the stomach is capable of providing ; exercise,
in the open air,promotes the secretion of the gastric juice.
It is  a good rule to proportion the quantity of our  food,
in a great measure, to  the amount of exercise we take : 
[17]
and if that exercise has been in the open air there is less
danger of excess.   The person of sedentary habits, who
scarcely walks abroad, should  eat  very sparingly, or he
will be troubled with nervousness, headache, and all the
horrors of indigestion.
  Young persons, who are growing, should have plenty
of food ;  if they are active and healthy, and the  food  is
of a proper kind and well prepared, there is little danger
of their taking too much.  But never tempt their appetites
by delicacies, when plain food is not relished.   When the
growth is attained,  and when childhood  sports and ex-
ercise are in a great measure abandoned—as is the case
with females, particularly,—then  great care  should be
taken to regulate the appetite, and never to take  such a
quantity of food at a time as to oppress and  disturb the
stomach.
  Variety in food is chiefly dangerous, because it tempts
to excess ; otherwise it  is  beneficial.   Let  no  person
think he  or she is certainly temperate,because but one kind
of food  is eaten.  It is more hurtful to take too much  of
one, than to use the same  quantity  of several kinds.—
Meats should always be sufficiently cooked.   It is a sav-
age custom, too generally  preval ent, to  eat meatin a
half-raw state, and only a very strong stomach can digest
it.
  The diet should always be  more  spare,  with  a large
proportion of vegetables and fruit, during summer. Ripe
fruits eaten temperately, in their  season, are wholesome.
Food should never be  eaten when it is hot—bread is very
unwholesome when eaten in this way.  Food  should be
eaten slowly.  One of the most usual causes of dispepsia,
arises from the haste in which we swallow our food without
sufficiently chewing it.  There ought to be  one hour, at
least, of quiet after every full meal, from those  pursuits
which tax the brain as well as those  which  exercise the
muscles.
  We next come to drink ;  what shall we drink ?  we will
answer the question as the Paddy did, by asking  another:
What was the original drink of man,  made for him by his
Creator, while in the garden of Paradise ?  You will an- 
[18]
swer at once, the pure streams of Eden.  Then, certain-
ly, to the unvitiated appetite, pure water, used in moder-
ate quantities, is the  most wholesome beverage.   Mopt
people drink too much because they drink too fast.   A
wine-glass of water, sipped slowly, will quench thirst  as
effectually, as a pint swallowed at a draught.  Dyspeptic
people should be careful to take but a  small  quantity of
drink at a time.  Children require more in proportion to
their food than adults.  But it is very injurious to them to
allow a habit of continual drinking, as you find in some
children.  It weakens the stomach, and renders them ir-
ritable and peevish.  Coffee affords  very little nourish-
ment, and is apt, if drank strong, to occasion  tremors of
the nerves.  It is very bad for bilious constitutions. Cof-
fee, well prepared,  and drank  in moderation, by  those
who exercise much and take considerable solid food, may
however, be used without much injury.
  Strong green tea relaxes the tone of the stomach,  and
excites the nervous system.  Persons of delicate constitu-
tions are almost always sure to be injured by  it.   Black
tea is much  less deliterious.  No kind of beverage should
be taken very hot—it injures the health and  impairs  di-
gestion.
  At the pyloric orifice of the stomach, there is  a mem-
branous  fold,  which acts something like  a  valve,  and
which is supposed to be capable of preventing the exit of
its contents  till they have been sufficiently acted upon for
the purpose of digestion.
  The  intestines  in the human  subject are usually from
six to eight  times as long as the individual to  whom they
belong.   They are divided into small and large intestines,
the former constituting about four-fifths of the whole. The
small intestines are divided into the duodenum, the jeje-
num, and the ileum.   The duodenum is so called from its
length being about twelve fingers in breath ;  and is abun-
dantly supplied witli absorbent vessels,called lacteals.from
the resemblance of the fluid they contain to milk.
   Mastication  and  deglutition are intimately connected
with digestion.  As soon as the food  is taken  into  the
mouth, it is cut by  the incisor  teeth, or  ground  by the 
[13]
molar ones, according to the nature  of it, into minute
parts, and in this way becomes  intimately mingled with
the saliva.  The powerful contraction of the muscles  of
the lower jaw, in mastication, increases the flow of this
fluid.  A large quantity of  saliva is at  all times poured
into the mouth,  but so long as we swallow with ease, we
are not aware of the amount of  the secretion.   But this
becomes evident when the throat  is inflamed, or deglu-
tition is effected from any cause. The presence of savory
food in the mouth (or indeed the thought of  a good meal
when we are hungry) increases to a great degree the ac-
tion of the salivary glands, and if mastication be properly
performed, every particle of food becomes completely sur-
rounded and mingled with the saliva.  It is  then carried
by the action of the tongue and of the muscles of the
mouth into the pharynx.   This part of  deglutition is vol-
untary ; but the  passage of the food through the pharynx
is wholly involuntary, and is performed very rapidly, so
that no part of it may enter the windpipe, over which it
passes.  To prevent the introduction  of any portion  of
the food into the  windpipe or air-passages, a very simple,
and,  at the  same time, a very effectual  contrivance has
been adopted.    There  is attached to  the  root of the
tongue, a small  cartilaginous body, called epiglottis, as it
is intended to cover, under certain circumstances, the
glottis  or opening- into  the   larynx, the organ  of voice,
which is the upper part  of  the windpipe.  The  ordinary
position of the epiglottis is perpendicular, so as  not to ob
struct the passage of air to the lungs.  But in  the act of
swallowing, the tongue  is  carried  backwards,  and the
epiglottis is brought directly over the  glottis,  so  as  to
completely close it.   It remains in this state till the food
has passed over it, and it is then restored to its  ordinary
position by  the  relaxation of the  muscles  and its own
elasticity.
  As the passage of the air to the lungs cannot with safe-
ty be long interrupted, it is  necessary that  this  part  of
swallowing should be, as we see it is, rapidly performed.
  As soon as it enters the oesophagus, it is carried slowly
downward towards the stomach.  It then enters the stom- 
[20]
ach, and there undergoes a change, by which it is brought
into a hemogeneous mass, neither fluid nor  solid,  which
is called chyme.  There has been great diversity of opin-
ion among physiologists as to the mode in  which this is
effected"  The opinion now generally received respecting
the mode of digestion is, that a peculiar  liquid secreted
by the stomach, and  called gastric  juice, has a solvent
power which enables  it to reduce the food  to an uniform
mass.   This is sometimes called the  theory  of  chem-
ical solution.
  The solvent power of the gastric juice has been prov-
ed  by  many experiments.   The celebrated Spallanani
caused  animals to swallow tubes with holes in them, con-
taining  food which had been  previously chewed, and  he
found that it was  converted into chyme.  He tried similar
experiments on himself, swallowing  at first wooden tubes
in which he put  various articles of food ; but as these
produced pain in  the stomach, he substituted linen bags,
and found that their  contents were   invariably  digested.
This he attributed to the solvent power of the  gastric
fluid, which penetrated the linen and dissolved  the  food.
It is therefore certain that the gastric juice, while  in the
stomach,  is capable of dissolving food taken into it ; and
though  evidently  possessing a solvent power, yet it seems
to be incapable of acting on anything endowed  with  life.
Worms, while living, will  often remain in the stomach
uninjured, at a time  when the hardest substances are un-
dergoing solution ;  but  the  moment these animals are
dead they are dissolved by the gastric liquor.
   It has been ascertained that,  in a healthy stomach, the
food, if not hard  of digestion, is changed into  chyme in
four or five hours, and that before this has  taken  place,
it is prevented from passing into the intestine, by a valve
situated at the pyloric orifice of the stomach, called pylo-
rus or door-keeper.   It has been supposed by some that
this valve has the property of determining  when the ali-
ment was sufficiently changed to allow it to pass,  that  it
gives free exit to chyme, but contracts  when undigested
substances attempt to enter the duodenum.  The food  is
not all converted into chyme at once, but  as fast as it  is
• 
[21]
 changed  it passes into the intestine,  only  two  or three
 ounces collecting in the pyloris extremity at a  time.
  After the food passes through the stomach it underg-oes
 an important change in the first intestine, or duodenum,
 as it is called.  In the stomach it is converted into chyme,
 and the process is  called chymification :  in  the intestine
 it undergoes what is called chylification,  in which it  is
 brought into such  a state, that  a peculiar fluid  called
 chyle is extracted from it by the absorbent vessels, whose
 mouths open in great abundance in this  organ.   The
 chyle is a thin substance somewhat resembling  milk, and
 is the fluid which is afterwards converted into  blood, for
 the nourishment of the body.   The chyle differs in quality
 according to the food on which we subsist.   If we have
 eaten much  animal food, it will be of  a white milky ap-
 pearance ;  if not, it will be thinner and moie transparent.
 It is not satisfactorily settled how the process of chylifica-
 tion is effected.   It seems to  be  probable, however, that
 liquor from the pancreas, and the bile from the  liver, are
 important agents in the  process.
  The  chyle is afterwards absorbed by the  lacteal  ves-
 sels, and goes into the blood to repair the waste  constant-
 ly going on in the body, while the other parts of the food,
 the excrementous matter, the nourishing part having been
 extracted from it, goes through the system and  is ejected
 from the bowels.
  We will now speak of the circulation of the blood. The
 agents  by which this is carried on are, the heart, the ar-
 teries, and the veins.  The heart is  a hollow  organ,  of
 an irregular conical shape,  and  muscular  and  fibrous
 structure.  Its situation is familiar to  all, it being direct-
 ly under where it is felt to beat.  It rests on the diaphragm,
 the  muscular membrane  which  separates the  chest
 from the  abdomen, and is supported at its base, which is
 uppermost, by the large blood-vessels with  which it  is
 connected.   The heart in man is a double  organ, and
 there is no direct communication after birth  between  its
two parts.  It is by one of these sides that the circulation
 is carried on in the lungs,  and by the other throughout
the rest of the body.  The right  side  sends the blood to 
[22]
the lungs, the left to the rest of the  body.  In the human
heart there are four cavities, two auricles, and two ven-
tricles.   The auricles are situated at the upper part, and
communicate freely with  the ventricles.   The vessels
which convey the blood from the heart to the extremities,
are called arteries.   This name was given to them by the
ancient anatomists,  from a belief that they contained air.
At the mouths of the two great arteries, that go  off from
the heart, there are three valves in each, which prevent
the blood that enters the arteries from returning to the
heart.  There  are no other valves found in  any part  of
the arterial system.  The veins  are the vessels by which
the blood is conveyed from the extremities to the  heart.
Many of the veins,  especially in the  extremities, are fur-
nished with  valves.  It must be apparent even to a casual
observer of vital  phenomena, the  blood is in  perpetual
motion during life.
  The mode in which the common operation of bleeding
from  a vein, either in the leg or arm, is performed, is a
convincing proof of the circulation of the blood.  In bleed-
ing from the arm, a ligature or bandage is placed around
it above the point at which the vein is to be opened.  The
blood returning to it through the heart, is of course inter-
rupted in its passage; the vein swells, because the artery,
which is deeper seated and is not compressed by the ban-
dage, continues to carry the blood to it,  and  if the vein is
then  opened below the ligature, the blood flows  freely;
but no  blood is obtained if the opening be  made  above
the ligature.  The  manner in which  the bleeding  from
the vessels that are divided in surgical operations is stop-
ped,  is another proof of the circulation of the blood.   In
the amputation of an  extremity, for example, that is, the
removal of  an arm or leg, the surgeon  ties only  the ar-
teries.   These carry the  blood from the heart to all parts
of the body, and the patient would soon bleed  to death,
unless some means were used to  prevent it.  The veins
which carry the blood back to the heart, though they are
usually  as  large  as the arteries, do not bleed,  and of
course are not tied. But the reader by this  time perhaps
will ask, what  is the cause of the circulation of the blood? 
[23]
what sets and keeps  it in motion  during a whole  life?
There has been much  diversity of opinion, says Dr. Hay-
ward,  among physiologists upon the question, whether
the blood is carried through the arteries by the action  of
the heart alone, or  whether the arteries  themselves act
upon their contents, and thus  aid in the circulation of the
blood.   The point may still be considered unsettled.  A
great majority, however, incline  to  the opinion, that it is
effected by the  combined action of  both.  The action of
the heart must be referred to  the vital principle.  It  may
then be said, that the blood is carried through  the arte-
ries chiefly by the ^action of the heart, aided, perhaps, by
the elasticity and contractile  power, which reside  in the
arterial coats; that the circulation through the capillary
system is effected entirely by the  capillaries themselves,
and that the  blood is thrown by them, into the ring,prob-
ably by the combined action of the causes just mentioned.
  It has been estimated  that two ounces of blood  are
thrown out of the heart at each contraction of the ventri-
cle or pulsation, and that the  blood constitutes about  one-
fifth part of the weight of the. body.   It follows,therefore,
that the quantity of blood is different in different individ-
uals according to the size of the body, varying in healthy
adults from twenty-five to thirty-five pounds, and in some
cases even more than this.  Now suppose that there are
seventy  pulsations in  a minute, the whole  blood of the
body,  even allowing it to  amount  to thirty-five pounds,
must pass through that organ  in less than three minutes.
And so important is the action of the heart, that  if it be
suspended for a moment, death ensues.   How beautiful
and well adapted  are the lines of the  excellent  Dr.
Watts:
      Our life contains a thousand  springs,
        And dies if one be gone;
      Strange that a harp  of thousand strings
        Should keep  in tune  so  long!

  That this  organ, constructed apparently  of such  frail
materials,  and exposed to  such great irregularity in ac-
tion during a long life, should perform  its  functions so 
[24]
perfectly, is calculated to give us  the most exalted  ideas
of the power and wisdom of the Creator of our bodies.
  The blood is the fluid from which all  other parts of the
body are formed.  When  drawn from the body, it soon
separates into  two parts,  one  liquid and the other sol-
id, which floats in it; the  liquid is called serum, and the
solid crassamentum.  This change is called the coagula-
tion  of the blood, and takes place in  about seven minutes
after it is drawn from the body.  The average tempera-
ture  of blood is about  one hundred  degrees of Fahren-
heit's thermometer.  All parts of the body, as before re-
marked, are formed from the blood, however dissimilar
they may be in  appearance,  structure, and  properties.
From  it is secreted all the solids as well as the fluids;
and  some of the solids  seem to possess properties very
unlike those of the blood, as the hair, the nails, and the
bones.  It is the  blood that repairs the waste that is go-
ing on in our organs, and it also gives a stimulus to the
brain and nervous system, without which they would be
incapable of action.  If the ordinary supply of blood that
is sent to the brain be cut  off, its  functions are immedi-
ately suspended;  and if blood be carried there which has
not  undergone the changes which are effected in it by
the lungs, its functions are destroyed.
  Respiration or breathing is the process by which air is
taken into the lungs and expelled from them. The act
by which the air is taken in, is called inspiration, and
that  by  which it is thrown out is called expiration.  The
respiratory apparatus embraces all  those organs, which
perform any part in the mechanical  process of respira-
tion.  The windpipe is a tube composed of  cartilaginous
rings, extending  from  the mouth into  the  lungs.  It is
situated in front of the passage to the stomach, and at its
upper extremity there  is a valve, the epiglottis,  already
noticed, which  prevents  the entrance of foreign substan-
ces into it.  As soon as  the windpipe reaches the lungs,
it is  divided into  two parts, one going  to each side, and
called  the bronchus, which is  the  seat  of bronchitis.
These subdivide into numerous smaller branches, which
finally terminate  in air cells.   The lungs occupy  a  large 
[25]
part  of the cavity  of the chest.   They  are divided into
five parts or lobes, three on the right side and two on the
left.  They  are  composed  almost entirely of air-tubes,
air-cells and blood  vessels; these, with the cellular mem-
brane that connects them, constitute, in fact, their whole
substance.
  They  are so vascular, that after air has once  been ad-
mitted into them, they are lighter than water.  A knowl-
edge of this fact has led to a mode of determining whether
infants supposed  to have been murdered, were born alive
or not.   If the lungs would  float  in water, it was decided
that the  children  must have breathed, and of course have
been born alive;  if on the contrary they sunk, it  was con-
sidered a proof that they had never breathed. The lungs
in the inferior  animals are  known by the popular name
of lights.  The air-tubes and air-cells are lined  by a mu-
cus membrane, and the lungs are covered on the exteri-
or by a serous membrane called the pleura, which is  the
seat of the disease known by the  name of pleurisy.  This
membrane not only covers the lungs on the  exterior,  but
lines also the chest, and is constantly lubricated  in health
by a serous fluid  which is exhaled from it.
  The air we take  into the lungs in the act of breathing,
and without  which life could not be sustained, is a com-
pound fluid, consisting of twenty-one  parts of  oxygen,
seventy-eight parts of nitrogen, and one  part of  carbonic
acid gas.  The quantity  of air thrown out of the lungs,
is somewhat less than that which  is taken  into them.
Some physiologists have fixed the amount lost at  one
eightieth part of the  volume taken into  the  lungs; which
would be  about  half a cubic  inch at  each  inspiration.
The quantity of azote or nitrogen, is nearly the  same un-
der ordinary circumstances, in expired  air as  in inspir-
ed.  The quantity  of oxygen is diminished by inspiration,
and that of carbonic acid gas  is increased.   The object
of respiration seems to be to bring the blood in contact
with the air  in the lungs, where it undergoes a change,
rendering it suitable for the purposes of nutrition. When
it is recollected, that atmospheric air is alone capable of
permanently supporting respiration, and that every adult 
[ 26]
individual  perspires about one million  cubic  inches  in
every  twenty-four hours; when it is borne in mind  how
essential this process is to  health and even life, that the
functions of the body cannot be perfectly performed if the
lungs  be  not properly  supplied, that the spirits are de-
pressed and the energies of the mind  impaired, it must
be obvious that too great care cannot be taken that the
apartments  in which we live should be  well  ventilated,
that too many persons  should not be crowded together,
and thus be compelled to  breathe air which has been al-
ready  respired,  but  that the lungs  should be constantly
furnished both by day and by night, with that air which
can alone  impart  vigor to the physical  and intellectual
system.
  There are other actions of common occurrence,  inti-
mately connected with respiration, such as sighing, yawn-
ing, coughing, sneezing, laughing and hiccup.
  Sighing, consists in  a full  and long-continued inspira-
tion; its purpose, when it is not connected with the state
of the mind, seems to be to facilitate the  passage  of the
blood through the  vessels of the lungs.
  Yawning, like sighing, consists of a full and  protract-
ed inspiration; but it differs from it in  being followed by
a slow expiration,  and  by being attended by an involun-
tary distention of the jaws.
  Coughing, is produced by a quick and powerful con-
traction of the diaphragm, which distends the lungs with
air, and this is driven forcibly by the contraction of the
abdominal muscles through  the trachea, for the purpose
of expelling any  foreign or irritating substance that  may
be lodged there or in the lungs.
  Sneezing, is an  involuntary action, caused by some ir-
ritating substance applied to the  mucous membrane  of
the nose.
  Laughing, is the effect of an inspiration, succeeded by
short, rapid,  and imperfect expirations.
  Hiccup,  is produced by a convulsive, rapid and invol-
untary contraction of the diaphragm.  In  a low state  of
protracted  disease, it is an alarming  symptom, and not
unfrequently precedes  dissolution. 
[27]
  A knowledge  of the  structure  and  functions of the
lungs, and  of the conditions  favorable  to  their healthy
action, is, therefore, very important; for on their welfare
depends that of every organ of the body.  And when we
consider the vast  number that annually  fall  victims to
pulmonary consumption, and that these are mostly among
the young and  promising,  we  cannot but  feel deeply in-
terested in obtaining some  acquaintance with the organi-
zation which is the seat  of that  affection, and with the
conditions most conducive to  the due  performance of its
functions and the preservation of its health.
  From  the explanation  already  given of the  structure
and uses of the  lungs, it  is obvious that several condi-
tions, which it  is our interest  to know and observe, are
essential to the  healthy  performance  of the  important
function of respiration.   And first,  we  may  remark,
among these is a healthy original  formation of the lungs.
No factin medicine is better established, than that which
proves the hereditary transmission of parents to children
of a constitutional liability to pulmonary disease.  Anoth-
er requisite to  the  well being of the lungs is, a due sup-
ply  of rich and  healthy  blood.   When, from defective
food or impaired digestion, the blood is impoverished  in
quality and rendered unfit for adequate  nutrition, the
lungs suffer, and that often to a fatal extent   So certain
is this fact, that in lower  animals, it is stated, tubercles
(the cause of incurable consumption) can  be produced in
the  lungs to almost  any extent,  by withholding a suffi-
ciency of nourishing food.
  The free and easy expansion of the  chest, is obviously
indispensable to the full play  and dilatation of the lungs;
whatever impedes it, either in dress or position, is preju-
dicial to health; and on the other  hand, whatever favors
the  free expansion of the chest, equally promotes  the
healthy fulfilment of the respiratory functions.
  Corsets  and tight lacing operate  most injuriously,  by
compressing the thoracic cavity,and impeding the due dila-
tation of the lungs, and in many instances, they give rise
to pulmonary consumption   Cases have  been produced,
in which the liver  was actually indented  by the extreme 
[28]
  pressure, occasioned by the suicidal practice of excessive
  lacing.   This destructive habit cannot be too highly cen-
  sured by all medical men, and especially by those who
  have the training of young females.  Mothers who  allow
  their daughters to destroy their healths in this way, can-
  not be innocent.   Some may say they would prevent it if
  they could.   Such futile  excuses are  useless.  Had you
  been faithful  and just with your child in  infancy, you
  could now govern it without difficulty.   For the beha-
  vior of every child who is not strictly moral and virtuous,
  his parents (if he  have them) are  almost,  if not entirely,
  responsible.   One of the greatest evils of our beloved
  country, and  one which perhaps  as much as any  other
  threatens to  destroy its  peace and prosperity, exists in
  the parental  education of our youth.  The reader will
  pardon  my thus  digressing, as this  is a subject  of so
  much vital importance.
    The admirable harmony established by the Creator
  between the various constituent parts of the animal frame,
  renders  it  impossible  to  pay regard  to,  or infringe the
  conditions required for, the health  of any one, without all
  the rest participating  in the benefit or  injury.  Thus,
„ while cheerful exercise in the open air and in the social
  circle is directly  and eminently conducive to the well-be-
  ing of the muscular system, the advantage does not stop
  here; the beneficent Creatqr having  kindly so ordered
  it, that the same  exercise shall be  scarcely less advanta-
  geous to the  proper performance  of the important  func-
  tion of respiration. Active exercise calls  the lungs into
  play, favors their expansion, promotes the circulation of
  the blood, and leads to their complete and healthy devel-
  opment.   The same  end  is  greatly facilitated  by that
  free and vigorous exercise of the voice,  which  so uni-
  formly accompanies and  enlivens the sports of the young,
  and which doubles the benefits derived from them,consid-
  ered as exercise.
    The excitement of the social and moral feelings among
  children engaged in play, is another  powerful tonic, the
  influence of which on the general  health ought not  to be
  overlooked; for the nervous influence is as indispensable 
[29]
to the right performance of respiration, as it is to the ac-
tion of the muscles or to the digestion of the food.
  But as we have already enlarged more than was in-
tended in the commencement, we shall be obliged to pass
over many points and  even parts  of the subject, of ex-
treme interest, by referring the reader to large profession-
al works; and close this little work,after stating a few fact
connected with the decay and dissolution of the  body.
And here I shall quote in  substance from the celebrated
Haller.   But as those causes operate incessantly in ren-
dering the matter of the body more dense, in diminishing
its irritability,  and in  augmenting the quantity of  earth,
it is not  possible but  decrepit old age must succeed.   In
it, the senses become partially destroyed, and the vis in-
sita of the muscles  becomes exceedingly weak, so that
the limbs lose their strength,  and  become,  especially
the legs, unable to direct the body;  that the callous  in-
sensibility of the nerves cannot be excited to perform the
office of generation; that  the very intestines, becoming
torpid, do not obey the habitual stimuli; that, by the  in-
duration of the intervertebral cartilages, the body  bends
forward; that by  the  falling out  of the teeth, the jaws,
now rendered shorter, do not support the  lips sufficiently;
and lastly, that the pulsations of the heart become one
half less frequent than in the infant state.
   Thus  at last, the  necessity of natural death approach-
es, although the greatest number  of persons are carried
off prematurely by disease.  One in a thousand, perhaps,
arrives  to the age of ninety, while  scarcely any exceed a
hundred.   Man is long lived when compared with other
animals; he is also more  tender than  any of them, has
looser flesh and less hard bones.   It is not  easy  to say
what was the cause in long lived people  of their longevi-
ty.  One cause seems to exist in the habits, to a consid-
erable degree at least, to sobriety, temperate diet,  peace-
able disposition, a mind not endowed with  very great vi-
vacity,  but cheerful, and little subject to care.
   Death from old age happens sometimes,  but rarely.  It
may be said to occur,  when the powers gradually  decay, 
[30]
first, of the voluntary muscles, then of the vital muscles,
and lastly of the heart itself; so that in an advanced age,
life ceases through mere weakness, rather than the op-
pression of any disease.  The heart  becomes unable to
propel the blood to the  extremities, the  pulse and heat
desert the feet and hands; yet the blood continues  to  be
sent from the heart into those arteries nearest to it, and
to be carried back from  thence;  the flame of life is thus
supported for a little while, which soon after we perceive
to be extinguished; when now the heart itself, being to-
tally deprived of its powers, and not  irritable by the blood
to any effectual motion, cannot propel the blood through
the lungs, that the  great  artery,  the aorta, may receive
its due quantity.   The last efforts of respiration are now
exerted,  to open a passage  for  the blood  through  the
lungs, until even the powers given by nature for perform-
ing the act of inspiration,  becoming unequal to their task,
cease.  Then, the left side of the heart neither receives
the blood nor is irritated, and therefore remains at rest;
while yet for a little time, the right  ventricle, and  lastly
the auricle of the same  side, receive  the blood  brought
by the veins from the cold and contracted limbs, and be-
ing irritated by it, continue to beat weakly.
  But at last, when the rest of the body has  become cold,
and the fat itself congealed, even this motion ceases, and
death becomes  complete. I shall call that death, says
Haller, when the heart  has become  totally deprived of
irritability; for its mere quiesence is not without hope  of
recuscitation: neither  does  the putrefaction, or insensi-
bility, or coldness of any part of the  body,  demonstrate
the death of the whole system; but all these things  when
joined together, and perpetually increasing, with the rig-
idity produced by the congelation  of the fat, in conse-
quence of rest and cold,  afford the signs of death in any
doubtful  case.  The body after death is decomposed and
destroyed by putrefaction.  Thus the fat, and the water,
and the gluten, being resolved, are dissipated; the earthy
matter deprived of its bonds of union, insensibly moulders
away and mixes with its  mother dust.   The  soul goes to
that place which God hath appointed it; and its indestruc- 
[31]
tibility  by death is proved incontrovertibly by  a very
common phenomenon; many people, when their  bodily
powers are wasted  and spent, give evident proofs of a
highly serene, vigorous, and even cheerful mind.

:) 

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