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UNITED STATES  OF AMERICA
WASHINGTON,  D. C.
SPO   16—67244-1
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SKETCHES  ON ANIMAL LIFE;


        AN INAUGURAL ESSAY,


   SUBMITTED TO THE CONSIDERATION
TOE HONOURABLE ROBERT SMITH, PROVOST,
AND OF THE
REGENTS OF THE UNIVERSITY OF MARYLAND,
JBF JOffJV CROMWELL,
OF HUNTINGDON COUNTY, PENNSYLVANIA, *fs^£*-v<. Jf,,^
OF THE BALTIMORE MEDICAL SOCIETY. (
^"1
 Diseases differ from each other only in the degree of accumulation or exhaustion of ex-
eitability.                                        Bromn-
 Diseases hare generick differences ;,they differ in kind as well as degree....Lowj ofNatitre.
         BALTIMORE:

PRINTED BY RALPH W. POMEROY
      NO. 12, LIGHT STREET.
             1814. 
? 
                       TO









        DOCTOR  JOHN CROMWELL,









   The following pages are gratefully inscribed,









           BY ONE, WHO AS A NEPHEW,








     IS INDEBTED FOR UNVARYING KINDNESS AND REGARD;








                   AS A PUPIL,









For every attention  which could facilitate his studies



             or enlarge his capacities. 
 
INTRODUCTION.
     ,1 PRESENT my reflections upon the subject of the
,  following dissertation, not from any voluntary indulgence
   of a disposition to  obtrude my immature  thoughts upon
   the notice of those, who,  I am satisfied  are much better
   qualified  than  I am,  to  examine  accurately and  reason
   justly; but in  compliance with a  formal obligation,  im-
*   posed by the caution and wisdom  of the institution whose
   favours I solicit.
      The understanding of mankind generally, has rarely
   been  quick in its apprehension of important truth ;  and,
   when acquired, seldom   been  active  in  cultivating  the
   advantages, to  be derived from its attainment.   On a few
   subjects, those particularly more immediately relating to
   man's every-day pursuits, his business and his pleasures,
   information is readily imbibed, and rapidly diffused; while
   on others with which his concern, though  all important,
   is of less frequent  occurrence, intelligence is received
   with  indifference,  and though conviction may admit the
   possibility of its practical utility, yet the motive not being
   immediate, the benefit is  entirely  neglected, or but par-
   tially pursued.   I speak of mankind as a body : and in il-
   lustration of the position, it would be unnecessary because
   the fact is familiar,  to adduce man's interest in religion,
   his indifference to its obligations, and his inattention to
   its advantages. Our profession, and its relation with gene-
   ral physical welfare, its capacities for contribution to the 
6
stock of human comfort and  happiness, and the frigid
apathy with which they have been contemplated, or  the
feeble attempts exerted to call them into action, is unfor-
tunately evidence sufficient for its establishment.  Let us
not be taunted with the imputation, that this is the cen-
sure of arrogated merit,  for disappointed ambition;  the
consequence affects society,  rather than the profession;
and if we  are qualified for the relation we assume  to it,
society can confer upon us no obligation, its most flatter-   •
ing notice will fall short even of reward.  In  a few in-
stances man has withdrawn his eager attention from  ex-
terior circumstances,  and directed it more  particularly
upon himself; he has paused to enquire, by what  means
he should most effectually preserve a health, or protract   *
an existence, both of which observation  had  convinced
might be lost; and both of which he had strong reasons for
supposing, had upon many  occasions, been  lost prema-
turely.  There  could be no difficulty in deciding upon the
means most extensively  conducive to the  attainment of
the object:  there could be no difficulty, for the mode was
solitary, it suggested itself, and the result has been  its
partial, though but partial  adoption.  A few occasional
attempts have been made by the delegated guardians of
social welfare,  to arrest the arm of ignorance and  rash-
ness, and  transfer the implements of man's safety or de-
struction, into hands guided by superior intelligence, and
purer motives.
    The constituted authorities of the society in which I
live, have thought proper to commit this power, into hands
qualified to direct its application ; I think they have ac-
ted wisely, and in obedience to the provisions of that pow-
er, I submit my claims to its patronage, in their present
form.   Were not compliance a duty, conscious imbecility 
7
   would have dictated a silence, which, though it cannot of-
   fer distinction, affords security.
      In concluding the performance of this task, I enter-
   tain no flattering presumption, that I have proposed any
   view of the subject it embraces, calculated to confer cele-
   brity upon myself, or to contribute in any degree, to the -.
   improvement or gratification of others.  My  work  will
   live for a day, and  be forgotten with the occasion which
   gave it birth : should it prove not unworthy of even this
1  ephemeral existence, my most earnest expectations will be
   gratified;  I am far from  confident that it  merits  any
   thing more.
       The inquiry will perhaps not be made, how far I can
   justly arrogate a claim to originality in the sentiments ad-
*  duced, in the following pages : but were that inquiry pro-
   posed, candour would compel me to acknowledge,  that the
   sentiments were mine by adoption, that my limited stock
   of knowledge, like  that of mankind in general, was more
   the result of observation, than invention ; I cheerfully ac-
   knowledge my obligations to the researches of respecta-
   ble writers, and the opinions of intelligent lecturers. Strict
   originality is seldom attainable, and is not essential to uti-
   lity ; I believe in common  understanding, it has no dis-
   tinct signification,  and if it were indispensable in the dis-
   cussions of science, I fear but few could be engaged in the
   pursuit.   In reviewing the  history of  man's social im-
   provement,  we cannot avoid an observance of the  intimivte
   connexion each succeeding  age has preserved with the
   circumstances which characterised  the condition of  its
   predecessor. It is true, that the knowledge which the for-
   mer had but just entered upon,  the latter has frequently
   extended, though rarely perfected.  New generations have
   profited by  the partial attainments of those who  had pas-
   sed away, sometimes even by their errours ; and intellee- 
8
  tual and moral refinement, appears to be  one connected
  chain, the links of which, with few exceptions, have for-
  tunately become more polished, as they were added.  The
  history of particular sciences, also, will afford us a proof
 how generally their cultivation and enlargement,  has de-
 pended upon  the  advantages derived from the attention
 previously bestowed upon' the  same subjects.   A few  of
 the most candid among  the  distinguished  cultivators  of
 knowledge, have  left us  a  voluntary record,  that they
 were indebted for their important discoveries to the sug-  *
 gestions of others, some  even to accident and casualty.  It
 is also true that individuals have lived at different periods,
 and under various circumstances, to whom the  foregoing
 remarks, would not intirely  apply  ; those men have  di-
 rected their view upon particular subjects,  beyond the ob-
 scurity of the present, and embraced  so  much in their
 comprehension, as to leave scarcely any thing, for suc-
 ceeding inference.  But, such men  as Bacon, Euclid, and
 Newton, exhibit phenomena  rather than  establish pre-
 cedent.
    It will not be necessary to prefer an apology, for  the
 freedom with  which I have noticed the sentiments of men
 occupying a more than ordinary elevation in publick regard.
 Names may become venerable,  but cannot consecrate opi-
 nions, and those  opinions when communicated, become
 publick property;  for every important truth which such
 men have planted in the fair  field of  science, they have
 conferred an obligation, which merits our gratitude ;  but
 that truth requires culture, and if they have unfortunately
 scattered  useless,  or noxious weeds  around it, general
 good demands, that the latter should be cleared away. But
 I contend for freedom of examination, I do not promise
correction. It is much easier to detect the errours of others,
 than to avoid them ourselves. 
SKETCHES,  &c.
    FROM the earliest period in which man's attention
to his own condition, and to the circumstances by which
he was surrounded, became aroused, the life he posses-
sed, and the properties of the  matter presented  to him,
were no doubt objects of curiosity and interest.  He was
conscious of an existence of whose mode and essence he
was ignorant; he was a witness to appearances, qualities
and changes, with whose principles he was unacquainted.
That surprise should be excited, and a wish for informa-
tion awakened, was a consequence unavoidable : and, in
pursuance of  this wish, we find that in all ages, and in eve-
ry state  of man, some portion of the human family, have
been seriously engaged in investigating the phenomena ap-
propriate to themselves, and applying to the objects among
which they were situated.   Those efforts it is true were
unskilful, and those attempts in a great measure, fruit-
less and unavailing; though the curiosity of all was ea-
ger to be gratified, few engaged earnestly in the pursuit;
that all  did not engage thus earnestly, is not more a mat-
 ter of surprise for that remote period, than at the present
 time : every  age has  had  its  philosophers; and a large
 proportion of society, engaged  in the various  pursuits  of
 pleasure or advantage, always have, and ever will, repose
 without exertion, upon the efforts of a few, in every thing
 not directly affecting their particular occupations.  That
 those efforts were unsuccessful, was perhaps a necessary
                           B 
10
consequence of time  and situation ; except where provi-
dence for its  wise purposes has  condescended to  become
the immediate instructor of man, his knowledge would ap-
pear to be in  a great measure the  result of education.—
The capacities which have been given him, must be exer-
cised,  he must become familiar with  his  own powers,
and learn to direct their operations.   In proportion as his
wants are multiplied, those capacities become enlarged,
and when necessity no longer presses  him, pleasure  and
curiosity, afford him motives  for action.   But time,  mu-
tual efforts, and extended observation, are indispensable to
the attainment of all those objects.
    It would be foreign to the present purpose, to attempt
a regular detail of the  objects and modes, of human re-
search and knowledge  ; since the creation of man, those
motives have always existed,  and to a degree, have been
at all times indulged.  The  laws of nature as before ob-
served, have been in constant operation, in and  around
him; and  he  has ever  been  solicitous  for their evolu-
tion.   The intelligence derived immediately from  the
senses, would naturally become the first subjects of exa-
mination :  and we accordingly discover the earliest re-
searches  directed  to  familiar objects.   I have no concern
in this place with the progress of natural philosophy, ex-
cept to shew  that early attention  had  been paid to the
forms and  conditions of life ; the result of which  has
been the establishment of a scale of existence, at the head
of which man assumed his station.   Experience  has con-
firmed his claim ; and improving knowledge has increas-
ed his desire to become more  intimately acquainted with
the principles on which that  existence  depends.   Those
reflections, will perhaps be  called  the  speculations of
youth; I acknowledge  it, and beg for indulgence: but I 
11
thought it not amiss to go back for a moment, to simple
truth : for it really appears to me, that in the progress of
improvement, man has acquired a confidence in his pow-
ers, from which he hopes to subject much more to their
control,  than his  situation requires,  or providence  in-
tended :  system has been  growing upon system, until we
have almost made a world for ourselves ; the rage for ge-
neralization has overthrown distinction  and not  unfre-
quently I fear, buried truth  amidst its ruins.  But the li-
mits of duty shall not be transgressed, nor the restraints
of confined  understanding forgotten :  I mean to  apply
the remark to the subject before us: animal life has been
examined, opinions formed, and maxims established, which
in my humble apprehension, though ingenious are arbi-
trary, though beautiful and interesting, are unnatural and
unfounded.   I will investigate the subject with what abi-
lity I can, I disclaim all self-sufficiency  and confidence.
    The result of all the enquiries directed to natural ob-
jects has been an agreement in establishing their rela-
tion to three prominent classes,  the most distinguished of
which has been made  to embrace the subjects of the ani-
mal kingdom.  Nor  have the   phenomena  of vegetable
life, and  mineral  organization  been overlooked ; we are
now satisfied that  nothing exists either in vain, or by ac-
cident.   An active principle pervades all nature, and pre-
sents to us every  where proofs  of its existence. Though
unable to ascertain what those laws  are, governing the
properties of substances, wanting the more familiar signs
of life,  we have reason to believe,  that those substances
are not dead. We see  effects which are uniform, and qua-
lities which in the natural  condition are permanent.  I
speak of what has been called  inert matter :  that condi-
tion which nature has wisely impressed for  the fulfilment
of  her purposes, upon a part of her works.   In tracing 
12
 the properties and modifications of the substances presen-
 ted to us under this character,  we have been engaged in
 investigating one of the most  important departments of.
 our natural or physical relation:  and in nothing perhaps
 has our industry been more amply rewarded.  Those mo-
 difications apply to us in ways innumerable, and  those
 properties reach and affect us, in a manner which we per-
 ceive^ but find a difficulty in comprehending.   We have
 succeeded in converting many of them to the  improve-
 ment of our condition.  In the  vegetable classes we dis-
 cover a nearer approach to us, even in x>byious circum-
 stances : their structure more nearly resembles ours, and
 they are affected in a limitted degree, by the same causes ;
 they live sensibly;  for  they grow and propagate  their
 species ; they require  nourishment, are affected toy nox-
 ious causes, and may even lose altogether their peculiar
 life.   What that peculiar life  is,  is the difficulty which
 presents itself on every hand ; we see some evidence of it
 in the arrangement and organization of common matter :
 we see it more plainly in the structure, growth, self-pre-
 serving and self-propagating  power of living vegetables ;
 and more distinctly  still in its animal condition.  Between
 the vegetable and animal, we find one striking analogy ;
 lop the vegetable, and it grows again,  mutilate the ani-
 mal, and  you  witness reproduction.  But there  is a dif-
ference, great by the  design of providence;  and for its
 object, perfect in its accomplishment;  there are animal
 actions  and operations.   If the vegetable possess  those
 actions and operations, it is in  too  confined a degree to
 give  them acharacteristick ; the peculiar influence of cer-
tain agents upon particular vegetables,  as the  Mimosa,
Dionea, &c. or possibly in some measure upon them all,
 is involved in total  obscurity,  and  at most  can  only en- 
IS
large in a degree their living capacities.   And does  ani-
mal life really possess in a degree, and a very considera-
ble degree,  powers  of recovery  and  self-preservation 2 '
What supports animal life for a length of time during the
abstraction  of nearly all foreign  stimuli ?  What resists
the influence of noxious causes ? What reunites a broken
bone ? What reproduces destroyed muscle and membrane I
What restores an emaciated body to original  size and vi-
gour ? Animal life then is not simply  a principle of me-
chanicks, nor a living animal body a mere machine; sub-
ject only  to the operation of a solitary law,  and affected
by a  single cause, differing alone  in its force of applica-
tion,  and  sum of effect.  It is advanced upon authority to
which in  the general, I feel pleasure  in  doing homage;
that matter in all its forms is in itself quiescent, from the
waves moved by the wind, and  the sand impelled by the
waves, up to the human body, controled  by its appropri-
ate stimuli.   The only difference consisting in  the inter-
ruption or uniformity of  the impulse.  And that life  in
its sensible state, is the effect of stimuli,  acting upon the
sensibility and excitability which  are extended over every
external and internal part of the  body.  This conclusion
appears just, but I confess does not to me obviate perplexi-
ty.   What is this sensibility and excitability diffused over
the whole body ?  What I would ask, created the princi-
ple of life ?  Can we form to ourselves any rational idea
of an effect produced by  what  we call stimuli, in which
effect life shall consist, absolutely ?  Is not this effect re-
lative only ?  Take for instance  the only presumable case,
for illustration, the very one insisted upon in support  of
the advanced position; suppose a body suddenly deprived
of allits sensible signs of life; in this state apply the arti-
ficial modes of restoration successfully; what is the infer- 
14
ence ?  Do you give it life positively ?  Was its life ex-
tinct ?  No : Its life, or living capacity though greatly re-
duced, remained, and you applied the agents fitted to call
it into more free action;  an hour longer, and though the
materials of the  body  would have remained unchanged,
you could not have forced it into  the living condition :
your stimulus then would have  been the voice of Canute
to the  waters of the Hellespont.
    I shall endeavour to shew  by and  by that this prin-
ciple is subject to something more than mere rise and fall,
and that it responds to agents differing in kind as well as
degree.  I have in vain endeavoured to persuade myself,
that there was required but a particular sum of action in
health, or that there was but  one cause of disease.   I
cannot believe that stimulus and excitement in their ordi-
nary acceptation, are all that is necessary for the produc-
tion of either.  I have  said that an active principle per-
vades all nature, and presents to us every where proofs
of its existence.  What this active principle is, is a ques-
tion which has been ever occurring,  and never has, nor
ever can be answered.  That such a principle does  exist,
the evidence of our senses forbids us to doubt.  From the
most complex and perfect condition of created substance,
down to  the simplest form of erganick matter, we witness
its existence; it is life in all its forms adapted to the cir-
cumstances in which it is  placed.  Perhaps  all we can
know respecting  it, distinct from its actions and opera-
tions, is  comprised in the beautiful  saying, that it was the
gift of the Almighty when  he  called a world into being;
that it shall continue in its appropriate forms so long as
he wills, and be recalled at his pleasure.   Life can never
be known in the abstract,  it is scrutablc only by  its phe-
nomena, its operations and its effects.   Its particular na- 
                          15

ture can never be defined, for it can never be subjected
to the cognizance of the senses.   As well might  we at-
tempt  to ascertain the  peculiar essence of the infinitely
diversified qualities of  substances, and account  for the
varied  effects of  their endless combinations.   It is this
power in animals by which their actions are performed
when living ;  by the performance of those actions we dis-
tinguish certainly living from dead animal matter, and it
is to its  condition in animal bodies, and more particularly
to its phenomena in man, that  we are now to confine our
attention.
    Between that principle of vitality in animals which we
are here considering, and the intelligent faculty called
mind, there does not appear to me any specifick connex-
ion ; I hold them as radically distinct, and find it impos-
sible to  believe with a distinguished medical philosopher
of our  country, that  "mind  and body were cast in the
same mould."  This governing faculty  of man, equally
inscrutable  with the principle in question and known only
by its operations, frequently exercises those powers pecu-
liar to itself, in full energy, when the animal actions are
sunk to  a point of feebleness, indicative of extreme decay.
We will adduce in evidence the condition of the mind in
protracted indisposition, and even in the progress  of ordi-
nary disease to a fatal termination, the mind's operations in
reviewing the past, examining the present, and anticipa-
ting the future,  are  upon  many  occasions equally lucid,
energetick and correct, as they had been during health.
It has been asserted, and  not  without strong indications
of accuracy, that they were frequently more so.   On  the
other hand we occasionally see the natural actions of the
animal powers, carried on  with their  customary vigour,
at a time when the intelligent functions are greatly im- 
16
paired, sometimes when they are totally suspended, and
consciousness itself extinct. The forms of apoplexy,  inju-
ries inflicted upon the head, the  effects of particular arti-
cles, and certain states of mania, &c establish the latter
position.  A reference also to inferior animals, perfect in
their kind as animals, but destitute we believe of a dis-
tinct intelligent faculty, would tend to weaken the proba-
bility of essential connexion.  And we  discover  a  prin-
ciple  less perfect indeed, but bearing an analogy to this
power, in the  whole vegetable family, and exercising its
laws over the forms and arrangements of common mat-
ter.   How far we are to remove the specifick differences
between the principle governing the conditions of matter
In those different states; or whether that  difference will
apply more  to the degree than the kind  of life, is a pro-
Mem of difficult solution.  The  fair presumption would
appear to be, that life is changed to become adapted to the
organization whose  purposes it is to serve.  This  deci-
sion is however unimportant, we  have sufficient evidence to
designate the distinction.  The  doctrine of indivisibility,
in animal and intelligent action, has met with many advo-
cates : and has,  1 think  been too much insisted  upon in
order to favour  particular systems built  upon the sup-
posed principles of our science.   Even the weight of that
imposing authority previously  referred to, has failed to
convince me,  "that the faculties  of the mind act  only
by reflection from impressions upon the body ;" indepen-
dent df the subtleties of materialism* in  which  such an
admission involves us, it can never contribute to the at-
tainment of knowledge to call  in aid of  one unknown

  *Np imputation of materialism is here aimed at the author of the
sentiment quoted.   His mind though not great enough to avoid  errour,
was too good to indulge in mischief. 
17
power, another equally obscure.  Though we must always
admire, I think we ought to avoid confounding, the happy
relation between the great  ruling  faculties  whose com-
bined effect confer upon man his decided pre-eminence.
    Animal life has been emphatically called " a forced
state."  If by this is meant to be conveyed the sentiment
which the language would appear to import, and in which
sense I believe it has generally been received, viz :  that it
is an artificial condition dependent upon a particular sum
of one kind of impulse,  effected by agents for the most
part foreign to the body,  I cannot subscribe to it: it sim-
plifies the mode of life it is true, but it violates every
day's observation.  On this supposition  there is an as-
sumed principle  in the body, on which  all  the various
agents which affect us, act alike, differing only in degree:
these diversified  natural actions which constitute the phe-
nomena of life, are all the result of a solitary law;  and
according to this supposition too, so long as this principle
retained its capacity  to be acted upon, and those agents
could be applied, health  ought not to fall off, nor death
to make its approach.  Where life  would cease  under
those circumstances, it would be difficult to divine.  That
a capacity  to be impressed, and one highly  sensible, does
exist, we well know,  but  are we  prepared to  admit that
the effects  of that impression are of one kind only ?  Are
not the material agents around us, possessed of qualities
essentially and infinitely diversified ?  Are not those quali-
ties active ? And are we not in a greater or  less degree
constantly obnoxious to their  effect ?  and if those combi-
nations of matter result in properties essentially distinct,
and those properties are active when applied to the living
principle sensible to  their action, will not the cause and
consequence correspond ?  I  should hesitate to affix a ne-
                          C 
18
gative.  May I be permitted to ask, for I will not forget
that I am a stranger in  the land  of science.   May I be
permitted to ask, whether air, drink, foock exercise, wine,
opium, mercury, and arsenick, are causes identically  si-
milar in kind, various only in force ?  Is  the natural con-
sequence of natural action in the body, the same with the
effect of hurtful causes,  admiting the asserted modifica-
tion ?  Is disease and health one action,  the former con-
sisting in too much,  or too little action ? And is this the
only variety among diseases ?  Are phrenitis  and syphi-
lis, small-pox and gout,  measles and rheumatism,  hoop-
ing cough and scarlatina, all members of the same  fami-
ly; having the same continuance, the same  language, the
same manners,  and  the  same  principles ? In short to
come at the subject in question, is every effect of impres-
sion upon the living principle, simply  a reaction ?   Shall
we then be safe in concluding that animal  life bears no
just parallel  " with the oscillations of a pendulum, or the
vibrations of a musical chord."   That it does not neces-
sarily consist in any  precise  sum of  effect  produced  by
particular agents, which effect is individual  and uniform ?
The proof of this negative would rest with  the fact, that
those agents may  be in a considerable degree weakened
or withdrawn, without either  death or disease occurring
as a consequence.   We know certainly, that  the powers
of the system will, (if I may use such phraseology,) make
life for themselves,  for  a considerable  time, under cir-
cumstances the least friendly;  and it is  somewhat singu-
lar that the^advoeates of indispensable force from foreign
sources, should have cited in support of their opinion, the
story  of horses subsisting for three weeks  upon cedar
chips, and a dog living twenty days upon the indigestible
cover of an old bible; it is more extraordinary still, that 
19
this  citation should have been immediately followed by
the just remark, that the food stimulates the whole body
by means of the process of digestion which goes forward
in the stomach.  The living principle is not  passive, it
acts  when acted on, and the  sensibility to impression, and
faculty for  operation, are both the result of fixed, regu-
lar, immutable laws, laws  impressed  upon matter  for
heaven's wise purposes, and accommodated to the objects
it was intended to accomplish. Neither health nor disease
can be reduced to a single principle, or an individual ef-
fect.   Should it be urged in objection to the admission of
various agents possessing peculiar qualities and appro-
priate effects when  applied  to the living body, that it is
carrying us back to the era antecedent to  the establish-
ment  of system in  our profession.  I can  only answer,
that when we have been led astray in the prosecution of
a journey, by the indulgence of fancy and imagination,  I
know no better way of  regaining the right path, than by
retracing our steps until we arrive at a road with which
we are more familiar, even  should that movement  carry
us back to the point, at which we set out.
    In a captivating theory of animal vitality, long the fa-
vourite child of medical philosophy, and which grew and
flourished under the fostering care of general  notice, its
ingenious author has brought us almost into contact, with
the important desideratum.   He fancifully imagined that
a certain  quantity of sensitive  principle,  was  bestowed
upon us at birth,  destined to  controul the actions and
operations of the powers over which it presided.   This
principle, capable  of receiving and communicating  im-
pression, was so regulated,  that when a moderate demand
was made upon it, its actions balanced its powers,  and
equilibrium, in other words health was produced:  when 
20
the demand was increased, its capacities were exhausted
in proportion to the sum of that demand ; and when it was
reduced or withheld, those capacities  became enlarged.
But strange to relate, the body dependent upon those capa-
cities was weakened in proportion as they increased. Here
then we  have  the singular phenomena of an  increasing
quantity of the principle of life, while life itself was ver-
ging to extinction.   As  we approached the grave, the
essential principle of existence was augmented, but was
inactive,  or acted only to pervert the purposes for which
it was given.  This  condition  of  that principle, has been
called morbid or accumulated excitability; and as a fami-
liar instance of such condition, we are referred to the
state  of digestive organ, when food has been  extraordi-
narily withheld :  under those  circumstances we are told
that death takes place after a full meal, from excess of
stimulant effect upon this accumulated excitable principle.
Though we are left  to conjecture as to the peculiar mode
of death, from the causes assigned, I believe  we  under-
stand the inference  as far as  it is  intelligible : yet as I
am not satisfied of its correctness, I would beg leave  to     i
suggest a different mode of explanation.  I shall say in
another place, that when the  natural actions of any  part
of the body are healthily performed, such part is supplied
by the vital functions, with the energies necessary for the
performance of that action.   That in proportfbn to the
demand of such part (within a certain range,) will be the
supply; when the former is reduced,  the latter is dimi-
nished.  Now when  the stomach has less than usual of
this natural action to perform, by the abstraction of food,
its powers are weakened: withhold this material  almost
or altogether,  and its peculiar energies fall  very low :
present to it now a full meal,  and what is the conse- 
21
quence ? its energies  cannot  be  immediately supplied,
and it has  a work  to  accomplish, for which it possesses
no  adequate  powers ; its  actions  are  entirely  over-
whelmed, and its life ceases :  it is  a  vital organ, and
from laws  of the animal economy, which we do not com-
prehend when any vital organ  has its life taken away,
the whole  body falls into sympathy, and the animal dies.
Something analogous to this  obtains over the whole cir-
cle  of animal  actions ; confines the motions of  a limb,
the arm for instance, or restrain them all together, while
the general body is kept in ordinary health ; what is the
result established by observation ? We shall find  after a
few days inaction;  a sensible decline of its powers ; con-
tinue the disuse, and its muscles contract but feebly.  At
this time direct the will upon those muscles, and call for
a sudden exertion of all its powers ; their small stock of
energy, is exhausted in the effort, and the arm is instant-
ly after powerless.  Here, in  the state of  quiet, the  ac-
 tion  and energy,  have  been proportionate, both greatly
 diminished ; in  this  case, too,  the limb has fallen off
 somewhat in its life, its nutrition has  been less  perfect,
 and its volume is lessened.  But the arm is not necessa-
 rily a vital  member, and under favourable circumstances
 will recover both its life and its powers.
     If those reasonings  are correct, and I flatter myself
 they approach the  truth,  would not  the inference esta-
 blish the opposite  of  the  conclusion proposed ?  would it
 not under those circumstances  point out a defect rather
 than  excess of the  living principle ? and should we not
 thus fix a condition more rational and  consistent, by ma-
 king the loss of vitality,  instead of its increase, co-rela-
 tive with  the lapse towards the  tomb. 
22
    The eharacteristick difference of the active principle,
 in other words life, though not the result of any combi-
 nation of matter,  appears to be intimately connected  as
 it regards its perfection, with arrangement and structure.
 In common matter it has been considered simple, and has
 received  the comprehensive appellation of attraction.—
 As we  rise in the scale to  vegetable, and higher still to
 animal  structure,  it seems  to have  been improved, and
 adapted to change of form : and in the latter, the con-
 nexion between the constitution of the principle, and the
 organization of the matter, becomes  close and intimate.
 This discrimination has been long since established ; and
 even among those who were anxious to give the soul a
 presence chamber in  the  body, there  were apartments
 assigned for the subordinate ministry of the animal prin-
principle.  It would be improper to attempt  a history
of the various opinions upon this subjeet; they  have agi-
tated all ages of  medicine, and some 6*f them have esca-
ped the oblivion, thrown around  the  systems  to  which
 they gave a character.
    Though the  Anima Medica, the intelligent principle,
 an extensible  soul,  and  the serial spirit, with a long list
 of worthy associates, have gone quietly to rest, we have
 still wandering about, a materia vitcc diffusa ;  a vis me-
 dicatrix naturae, and a principle of excitability.  I do not
 presume to censure, or condemn; we must have language
 to convey our impressions, and  our only guard  against its
 abuse, is care in its selection.
    Anatomy has rendered us familiar with animal struc-
ture, and impressions derived from observation  connected
with that acquaintance, have directed our attention to the
brain  and nervous system.  It may be questionable, in-
deed, how far a knowledge  of structure acquired from 
23
anatomy, will contribute to unfold the mysteries of ani-
mal vitality ; but it is at least rational and interesting, to
examine its general laws, and their connexions with the
body, so far as they can be  established, by observation
and experiment.  Too much  has no doubt, been anticipa-
ted from this source.   A  hope has been  indulged that
even  the philosophy of the  mind,  might receive  some
light from anatomical research, but hitherto  dissection
has been unproductive in this particular;  nor has an ac-
quaintance with the minds operations, opened the way to
any thing more than a partial knowledge of the physio-
logy of the body.   Yet in the pursuit of information, the
disappointments  of extravagant expectation,  are not to
cut us  off  from the benefits of that intelligence, which
has been rendered accessible.
    The effects of injuries inflicted  upon the brain, of li-
gatures and pressure upon the nerves, have induced us to
believe that they were greatly concerned, as instruments,
 in performance of animal actions,1 and operations. In tra-
 cing the distribution of the  latter by dissection, we find
 them directing their course to every important part; and
 in greatest number and size generally, to parts  destined
 to the performance of most vigorous action.   And  al-
 though we cannot detect sensibly, the nervous substance,
 in every portion of the body, we have no doubt  the hand
 of omnipotence can have established connexions, far  be-
 yond the point, at  which the  eye and the knife  of  the
 anatomist have ceased to find  an object.   Various cir-
 cumstances occurring  in the progress of research, have
 led us  to consider the nerves the media of sensation  and
 action.   Experiments made upon particular nerves, with
 a view of discovering their relation to the  organs,  to
 whieh they were appropriate ; together  with the effect 
24
 of particular accidents upon the parts they affected, have
 given rise to that opinion, and to the present day, multi-
 plied facts have only tended to confirm its probable accu-
 racy.   When it becomes established, that the nerves were
 subject to the influence of all agents applied to them, in a
 greater or less degree, and that  the actions and opera-
 tions of the body  were effected through that medium, a
 capacity was attributed to them, designated  by the term
 energy. The reception of this principle of nervous energy
 as an auxiliary  in the prosecution of  researches into
 animal life, was perhaps the most momentous occurrence
 in the history of that science.   Though it was for a long
 time the parent of errour,  confusion and absurdity, if we
 possess at this day, any correct knowledge of animal ac-
 tions, it is in my apprehension, the  great ground work on
 which that knowledge has been raised.   Here it enqui-
 red what  was the  precise  nature  of this energy, my own
 impressions upon the subject would lead to a candid de-
 claration, that it was involved in total mystery.   We be-
 lieve there is  such a principle, from  witnessing actions
 or operations, upon  the  application of  certain  agents,
 which actions  or  operations  constitute what we under-
 stand by the term  life.  The specifick principle, in other-
 words, the energy  itself, cannot be rendered obvious, we
 know it but from its effects.  It  does not appear to  be
 the consequence of any thing peculiar to the  structure of
 the nerves ; and we have  justly,  I  think,  discarded  the
 systems built upon conjectures deduced from a regard to
that structure.   Every thing perhaps which we should be
 safe in advancing,  may be comprised in a repetition of the
asserted belief touching life in  all  its  forms,  that it is
an incomprehensible condition of matter, arranged by in-
finite intelligence.   We believe that the nervous system 
25
has been assigned an important agency  in the preserva-
tion of the phenomena of life, and that agency ,we refer
to a principle which we call energy.
    The correct performance of the operations of the ani-
mal body in the aggregate, constitutes the healthy or natu-
ral condition of that body :   this is the only definition we
can have  of  health.  This performance of  the  natural
actions we attribute to the agency of nervous energy, and
this latter again depends for its support upon the actions
produced.  A mutual relation is thus established, and an
equipoise preserved.  This  equipoise is the essential prin-
 ciple of health.
    The  natural action is not one and the same over the
 whole body : there are  various, distinct,  and  separate
 functions, or rather effects of this action in parts, essen-
 tial to health ; any change in those functions, is the proof
 of disease, or a diviation from the natural state.
    The  inference  then, attempted to  be established, is,
 that  the nervous  energy being the principle  of action, ac-
 tion  and  energy would bear a just relation.   That as ac-
 tion  was the result of energy : the operation of that ac-
 tion  was in turn, the production of  that energy :  action
 can only be  performed through the  medium of energy ;
 and the sum of the former must always correspond to that
 of the latter; the limb in a state of disuse, will illustrate
 this  position.
     I think it not improper to notice an  errour or (at least
 an ambiguity) which has crept into our phraseology, upon
 a part of the subject  we  are  now considering.  It is in
 familiar use, not among the uninformed  only,  but with
 members, and distinguished one's too, of our profession, to
 say, that when one natural action of the body ceases, or
 is subtracted by accident  or disease, such  defect is sup-
                             D 
w
pji#d by the increased action of .others, or of all the rest:
tjiat the capacity of the whole, or of parts to be acted on,
arc augmented in a ratio proportionate to the preservation
of the original sum of action.   It is not necessary to ad-
duce t&e instances cited in support of this assertion,  such
as the Joss of an active part, the suspension of a particu-
lar  function, #c.   This  appears- to me another mistake
on the score of accumulated,  genera),  pr partial .excita-
bility.   ^4 in accpunting for the  effects ascertained by
phservatjpnp y/kh^ has led tp tjhe errour, I would say, that
in consequence of tjip loss pf one part another part which
had shared naturally the same actions, is called upon by
the  necessities  of  the body, for more  than its ordinary
proamnion, of thaj; action, and. that energy for  the perfor-
mance of that action is gradually supplied, as the couse*-
^uence of the gradually jnejseasing action. Tfce distinction
thus set up, is as to the cause of increased action or power
in a part:  that it is not directly the result of the subtrac-
tion pr suspension pf one part pr action, but the eonser
qnence of a gradually acquired habit of aotipUa producing
by  the action itself; the energy necessary for its support*
Were the opposite  of this position true, in  proportion to
the  progressive uiutilatipn of tl»« body, would be its in*
creased vital ppwers: a consequence I presume too absurd
to receive support  0* require  refutation,  Jt is bj no
means clear to  me, that we are not distant from the facjt#
iu  the  opinions we have  adapted,  respecting a familiar
pecurreupe connected witJ* tkti  suhjeet, to  wit, in suppo-
sing that  when one eye or one ear has heen  deprived Qf
its  functions, the capacity of tfte remaining one, has wen
increased hj sui?h Jos?,  When such a \pst haj ©eeiH?re4*
we acquire £rom necessity a Jiabit of dependanee upon the
remaining one fop sigjjt,  pr souihJ, and. from this circumr 
                         27

stance are conscious of distinctness irt vision or hearing1.
We pterceive something of this kind, in the accuracy With
which we distinguish objects, in the voluntary closure of
one eye, when neither has  been injured; that the same
effect  does  not  take place  so sensibly, irt the artificial
stoppage of one  ear,  is  perhaps to be attributed to the
mechanical violence offered the auditory nerve, in produ-
cing the obstruction, suck violence' being propagated by
sympathy  to  the opposite ear.  Ory to admit that the
natural  Capacity does  become  increased, under the cir-
cumstances noticed, would only be to  prove, that the
nervous energy was more freely supplied in consequence
of the increased  demand made  upon it.  Were one arm
removed from the  body, and the  other confined  strictly
Within its ordinary limits  of action antecedent  to such
loss,  it would acquire increased force, extent or variety
of action.
    Particular causes may act in such a way, as to destroy
the natural relation between the principle and the action;
the  natural actions, are not only  subjeet to increase, or
diminution, but may be changed in kind.  On this  pre-
sumption, we hold the variety of  diseased actions in the
body. Every considerable effect upon the naturs* action,
produces some alteration in the kind of action. When the
natural action of a part is lessened, weakness is the con-
sequence ; its actions having been interrupted, or changed,
 its natural energies are not supplied : as the interruption
 continues,  the consequences are rendered sensible by the
loss  of power,  and  the establishment  of  disease, or an
altered condition, such  as  in inflammation.  When any
 agents,  nroternaturally increase the actions of the whole
 or a part, the energy is applied until the balance is lost:
The actions  being altered, tlie natural energies become 
28
wasted, and the actions not being of a proper kind to re-
produce them, the body or the part falls off, and in pro-
portion to the force and continuance of the cause, debility
or death is the consequence.  On  this principle, action
destroys vigour, and the system is sinking while the ac-
tions continue.   We can only save it, by reducing action
while the powers remain, and when the latter have fallen
low, by affording  it proper materials for the production
of energy.  When exciting causes are applied to the body,
or a part, they have been supposed to  effect an increase
of material action; but all the agents foreign to the natu-
ral economy of the body,  possess peculiar properties;
they can act only by  their properties, and if they do not
produce a modification of action, how, I would ask, does
Syphilitic and variolus virus, cause  each its appropriate
effect, and produce as a consequence, diseases uniform in
their character, and going on to the formation of matter
endued  with qualities identically  similar to that of the
exciting cause.  It is  true,  that  in the agency of every
cause,  we do not discover changes equally sensible; as we
approach the natural exciters this peculiar  effect is less
obvious.   Certain  materials appear to be almost limited
to a simple increase of  the natural  powers.   Were not
this the ease, we should  be exposed to danger, from
sources innumerable.
    Various  causes  affecting the  body in a sudden and
violent manner, consistent with their nature  or qualities,
produce effects without sensible  changes except as to de-
gree ;  such  for instance as in Syncope; the mind holds
control over the body,  and may  be sometimes affected in
such a manner as to produce the same  effect.  Here the
cause has interrupted the natural actions of the body, and
thrown it for a time, and to a degree, beyond the control 
29
of the laws of its own energy :  in this  case the actions
are suspended without a waste of  the energy;  when the
suspending cause ceases, action  and energy, soon regain
their relation, and the natural condition  is reestablished.
Were not this the act, were the energy exhausted, death
I  presume would occur from every case of general syn-
cope, as action could not be restored without energy, nor
energy reproduced without action.  If the  actions were
long suspended,  the energy would be lost, and  death a
necessary consequence.
    Poisons act  in  a manner  peculiar, and  unknown.
They possess specifick properties, and in accordance with
the relative force of those properties when applied to the
body, they interrupt or subdue the natural powers and
actions, and  subject it in a proportionate  degree, to the
laws of their own qualities.
    The  brain has  been  considered the great source of
nervous  energy;  and whatever importance observation
and experiment may have assigned to the apparently dis-
tinct properties of  nerves,  it seems reasonable to  con-
clude,  that an intimate connexion and dependance, exist
between  all the parts of the nervous system : the propor-
tion of that system  constituted by  the brain, is essential
to its perfection  and indispensable to  the  continued per-
formance of those actions in which complete life consists.
 On this  subject  our knowledge has made a pause, baf-
fled research, and almost forbids the hope, that it can  ever
become progressive.
    I here withdraw from a task to which  I feel unequal,
but whose performance it was a duty to attempt.   To
those  whose notice of this work is of most importance to
the writer, it is unnecessary to  suggest,  the confined and
partial view,  permitted by custom to works of this  cha- 
so
raeter, they  will not forget, nor shall I complain of that
restraint;  were the utmost licence indulged, I am aware
that limited indulgence  would still present insuperable
difficulty.  For whatever of truth this essay may contain,
I am indebted to others, its errours are the consequence of
my own misconception.
    To all the  the professors of  the institution, under
whose  auspices 1 prosecuted the  search for professional
acquirements, I  feel  sensibly,  and  acknowledge  with
pleasure, my serious obligations.   How far I have bene-
fited by their labours, is not here a question;  the effort
to confer advantage,  is entitled  to my  gratitude.  No
exertion has  been wanting, no aid withheld, which eouM
facilitate enquiry, or contribute to improvement.   Nor,
if I may indulge  a confidence in my own judgment upon
the occasion, has that exertion been deficient in skill, or
that aid inadequate  to  its object.  From the institution
as an individual,  I have  nothing  farther to expect:  but
I shall ever preserve a deeply rooted regard for its pros-
perity, and I indulge the hope that society  will be early
aroused to  a  full  sense  of  its important  connexion with
their welfare, and will do justice to the motives and the
merit which have raised it out of nothing, and supported
with honour,  what had been created with difficulty. 
                                ERRATA.


Page 16, line 10, for vegetable family read vegetable -world.
Page 21, line 9, for confines read confine; line 31 for co-relative read correlative.
Page 22, line 24, for materia vitce read materia vitas.
Page 24, line 16, for Here it enquired read Were it enquired.
Page 25, line 17, for or a deviation read or a deviation. 
 
 
 
  W7.
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