Bi

THE LIBRARY

OF
THE UNIVERSITY

OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID

ELEMENTS

OF

PHYSIOLOGY.

BY A. RICHERAND,

PBOFESSOR OF THE FACULTY OF MEDICINE OF PA1US, SURGEON IN CHIEF OF THK

HOSPITAL OF ST. I.OUIS, MEMBER OF THE ACADEMIES OF YIKXNA,

PETERSBURG, MADRID, TURIN, &C.

TRANSLATED FROM THE FRENCH,
BY G. J. M. DE LYS, M. D.

MEMBER OF THE ROYAL COLLE&E OF SURGEONS IN LONDON.

WITH ANNOTATIONS,

BY N. CHAPMAN, M. D.

Profesior of the Institutes and Practice of Medicine in the University of Pennsylvania;
COPIOUS NOTES AND AN APPENDIX,

BY JAMES COPLAND, M. D. OF LONDON;

AND ADDITIONAL NOTES,

BY JOHN D. GODMAN, M. D.

LECTURER ON ANATOMY AND PHYSIOLOGY.
FIFTH AMERICAN FROM THE LAST LONDON EDITION.

PHILADELPHIA :
PUBLISHED BY H. C. CAREY & I. T.K',.

IS25.

Eastern District of Pennsylvania, TO WIT:

BE IT REMEMBERED, That on the twenty-seventh day of Septem-
ber, in the fiftieth year of the Independence of the United States
of America, A. D. 1825,

H. C. CAREY & I. LEA,

of the said district, have deposited in this office, the title of a book, the right whereof thy
claim as proprietors, in the words following to wit.

«• Elements of Physiology. By A. Richerand, Professor of the Faculty of Medicine
' of Paris, Surgeon in Chief of the Hospital of St. Louis, Member of the Aca-
1 demies of Vienna, Petersburg, Madrid, Turin, &c. Translated from the French,
' by G. J. M. De Lys, M. D. Member of the Royal College of Surgeons in Lon-
' don. With Annotations, by N. Chapman, M. D. Professor of the Institutes and
' Practice of Medicine in the University of Pennsylvania; copious Notes and an
' Appendix, by James Copland, M. D. of London; and additional notes, by John
' D. Godman, M. D. Lecturer on Anatomy and Physiology. Fifth American,
' from the last London Edition."

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other prints."

D. CALDWELL,
Clerk of the Eastern District of Pennsylvania*

,

\v

TO

PHILIP SYNG PHYSICK, M. D.

PROFESSOR OF ANATOMY IX THE UNIVERSITY OF PENNSYLVANIA ;

WHO, BY HIS NATIVE GENIUS,

HAS GAINED A REPUTATION BEYOND THE POWER OF ACCIDENT J

WHOSE PROFESSIONAL SKILL,

HAS LONG BEEN A NATIONAL BENEFIT ; AND WHOSE ARDENT
DESIRE OF KNOWLEDGE IS ONLY EQUALLED

BY HIS SOLICITUDE TO DIFFUSE ITS BLESSINGS,

THE FIFTH AMERICAN EDITION OF
THIS WORK IS MOST EESPECFULLY

DEDICATED,

THE

AUTHOR'S ADVERTISEMENT

TO THE

FIFTH EDITION,*

IN preparing for the press this Fifth Edition of his work, the Author
has carefully revised and corrected it, in all its parts, so as to render it
more worthy of the success it has already obtained. The additions
which have been made, will be found not to consist of idle discourses, or
frivolous hypotheses. The ground-work and the order are the same, the
Author has merely added to the mass of facts, — supported, by additional
proofs, the opinions which he had advanced, — and developed those parts
of his subject, which, from being explained in too concise a manner,
might be involved in some degree of obscurity.

Among the variety of opinions which Criticism, oftener unjust than en-
lightened, has pronounced, in judging this work, there is one which re-
quires to be refuted, because it proceeds from an erroneous idea of what
an elementary work should be. The Author, it has been said ought to
have contented himself with giving a view of the present state of the sci-
ence, without any additions of his own, and he should have abstained
from inserting new opinions, which, until they had received the sanction
of the learned world, ought not to have been introduced into an elemen-
tary work. This objection may be answered, by considering that modern
Physiology being, in some measure, a new and regenerated science, there
will be found, in treating of it to its full extent, many deficiencies to be
filled up, and many doctrines evidently erroneous, for which truths are
to be substituted, which it is of importance to discover. Lavoisier, in
his Elements of Chemistry, set forth, in a methodical order, truths which
he himself had discovered : he introduced original ideas, not such as owe
an appearance of originality, to minute explanation of what is already
known, or to a general want of erudition, too prevalent in the present
day. One of his most illustrious colleagues, in describing the state of
the science, has likewise given a history of his discoveries and labours,
and men of the soundest judgment ascribe the astonishing progress of
chemistry, in a great measure, to the favourable circumstance of our
possessing elementary works written by the most distinguished chemists.

* Published 1811,

VI ADV ERTI S EM EX T .

The present work has been translated in England, in Spain, in Italy?
in Germany, and men of merit have not disdained the task : amongst
others, I may mention Mr. Robert Kerrison, Member of the Royal Col-
lege of Surgeons in London, author of a translation of these Elements
of Physiology, published in the year 1803.

Since the "publication of the Fourth Edition of this work, Professor
Sprengell has published his Institutes of Physiology.5* The date of that
new work, and the well deserved reputation^of its author, entitle it to be
considered as a faithful account of the state of physiological sciences in
Germany. In that work, the reader will be astonished to find it stated
that every thing in the human body is governed by polar influence, and
by the laws of antagonism ; that man is in a state of positive electricity ;
that his body is formed chiefly of oxygen : while the female body is in a
state of negative electricity, with a superabundant quantity of hydrogen
in the composition of its solids and fluids. Thus, by the premature ap-
plication of a few facts, borrowed from the physico-chemical sciences,
the learned of Germany have thrown back Physiology into the uncertain-
ty of conjectures and hypotheses.

* On the other hand, Gall, by his anatomical discoveries on the organi-
zation of the brain and nerves, and a few other Physiologists, by their
experiments on living animals, have been usefully employed in advanc-
ing the progress of Physiology. The author has been anxious to increase
the value of this new edition, by adding to it the result of their obser-
vations.

* Institutiones Physiologic ce. Amstelocl. 1809, 2 vols. 8 vo.

THE AUTHOR'S PREFACE.

THESE Elements of Physiology, which contain an abstract of the doc-
trines I have taught for several years past in my public lesctures, are
written on the model of the small work on Physiology of the great and
immortal Haller. I am far, however, from presuming to say that I have
equalled the merit of a work, which, as is remarked by a man of the
highest ability,* gave, when it appeared, a new aspect to the science,
and commanded universal approbation. If these Elements of Physiology
deserve any preference over that work, the honour is not due to the Au-
thor, but to the times in which he writes, enriched by the progress of
the physical sciences, with a multitude of data and results which may be
said to have rendered Physiology altogether a new science.

It will be easily perceived, that the plan I have adopted differs essen-
tially from that followed by several repectable physicians ; and that the
treatises on Physiology most recently published, resemble the present,
only in their title. In combining a great number of facts, in adding to
those already known, the result of my own observation and experience,
and in connecting them by a method that should unite accuracy and
simplicity, I have had it in view to keep a due measure between those
elementary works, whose conciseness approaches to obscurity and dry-
ness, and those in which the authors, omitting no detail, and exhausting
in a manner their subject, seem to have written only for those who have
leisure or inclination for the profoundest study.

Should any conceive that the present undertaking is above the capacity
of my age, I will say, even at the risk of a paradox, that young men are,
perhaps, fittest to compose elementary works ; because the difficulties
they have encountered in the study, are yet fresh in their memory, as well
as the steps which they have taken to overcome them ; and further, be-
cause their recent experience points out to them the defects and advan-
tages of the different methods of other instructors ;t so that he, who in
the shortest lapse of time, has carried to the greatest extent his own ac-
quisition of sound knowledge, will, in some respects, be the best guide to
his successors, in the difficult and perplexing parts of elementary study.

In the composition of the work, I have borne constantly in mind the
necessity tf sacrificing elegance to clearness, which I know to be the
most important merit of an elementary treatise. Further, I have through-
out followed, I believe, the same arrangement in the succession of the
subjects, and applied to the science of living man, the principle of the
Association of ideas, so well developed by Condillac, (in his Treatise on
the Art of Writing,) and to which that philosopher has shown, that all
the rules of the art are to be referred. Notwithstanding the rigorous law
to which I have subjected myself, I have, after the example of the an-
cients, and, among the moderns, of Bordeu, and of several other physi-
cians and physiologists of equal celebrity, thought myself justified in em-
ploying, when I felt it necessary, metaphorical expressions ; because, as
has been correctly observed by "a justly celebrated writer, if conciseness
do not consist in the art of reducing the number of words, still less does
it consist in depriving language of imagery. The conciseness which is
to be envied is that of Tacitus, at once eloquent and energetic ; and, far
from any fear that imagery should injure that deservedly admired com-

* " When Haller published his Printce Unfa; Pbysioloxite, which he valued most of all his works, a consider-
able sensation was excited in the schools. In works on the same subject, it was customary to find long disser-
tations, almost always void of proof, extraordinary opinions, or brilfiant fictions. It was matter of wonder, that
in Haller swr.rk, there should be found only numerous iaets, precise details, and direct inferences, &c."—

t" 1 'he best order in which truth can be set forth, is that in which it might naturally have been discovered ;
tor, the surest method of instructing others, is to lead them along the path which we ourselves have followed,
in our own instruction, in this way, we shall seem not so much to lay before them our own knowledge, as
to set themselves on the suavch and discovery of unknown truthB."--£0/n£/ftif.

Vlii PREFACE.

pression of style, figurative expressions are, indeed, those which comprise
in fewest words the greatest sum of ideas.*

Those who insist on meeting in a work on Physiology, with a romance
instead of the history of the animal economy, will, no doubt, reproach me
with having entirely neglected a great number of hypotheses, on the uses
of organs, ingenious or absurd ; with having omitted, for example, while
speaking of the spleen, to mention the opinion which considers that viscus
as the seat of mirth and laughter ; with having said nothing of the opinion
of those authors, who conceive it to maintain the equilibrium of the two
hypochondria, by counterpoising the liver ; nor even of the doctrine of
tne ancients who ascribed to it the secretion of the atra bilis, &c. To
recall such errors for the sake of elaborate refutation, would be wasting
much precious time in idle discussions, and possessing, as Bacon calls it,
the art of making one question bring forth a thousand, by answers more
and more unsatisfactory. I have chosen to forego all such vain parade,
from a clear conviction, that works of merit are as often distinguished by
some things, that are not to be found in them, as by those they do contain.

Several authors, in treating of the science of man, have indulged them-
selves in frequent excursion into the vast field of accessory sciences, and
have, without necessity, incorporated in their works whole chapters on
air, on sound, on light, and other subjects, which belong to the depart-
ment of natural philosophy and chemistry. Haller himself is not entire-
ly free of blame, for having discredited physiology by this borrowed dis-
play. I have introduced only such general ideas of the subject, as were
absolutely necessary to render my own intelligible, and were, indeed,
too closely connected with it, to admit of separation.

One of the principal faults of writers on physiology is, that they are apt
to fall into frequent repetitions 5 and that fault is often owing to the diffi-
culty of settling, satisfactorily, the limits of action, which are mutually
connected and dependent among themselves, and running into each other,
like those that are cawied on in the animal economy.

" In composition, one should avoid prolixity, because it is fatiguing to
" the mind ; digressions, because they divert the attention ; frequent divi-
" sions and sub-divisions, because they are perplexing ; and repetitions,
"because they are oppressive. What has been once said, an<J in its pro-
" per place, is clearer than if several times repeated elsewhere, "t In
following these precepts, (and they cannot be too much attended to,) one
raav» it is true, incur the risk of being thought superficial, by superficial
reaclers, who form their opinion of a work from the perusal of a single
chapter ; but a most ample compensation will be found in the opinion of
those, who choose to be thoroughly acquainted with a work, before they
pass on it their final judgment.

After having stated in what spirit this work has been written, I may
say something^ of the motives which have led to its publication. I would
mention in the first place, the advantage which, it might be expected,
would accrue to the science, and to those who are engaged in its pursuit ;
and, in the next place, the satisfaction which study has in store for him,
who bestows on it the time he can snatch from the laborious practice of
our art. In his short intervals of leisure from public instruction and
from professional duty, left to himself and his own thoughts, in the silence
of study, and in the calm of meditation, he looks down, with an eye of
pity, on those, who drag on, through the lowest intrigues, a despicable ex-
istence, and there finds his consolation against the endless vexations that
are prepared for him by supercilious ignorance, and jealous mediocrity.

*" Df la-Literature consideie danssts rapports avec les Institutions Sociaies per Madame de Stael-Holstein,
•f Condillac Essai sin- rOrigine des Cormoissanees humaines, seronde partie, sect. ii. chap. iv.

PRELIMINARY DISCOURSE.

PHYSIOLOGY* is the science of life. The term life is applied to an ag-
gregate of phenomena, which manifest themselves in succession, for a
limited time, in organized bodies. Combustion is likewise only a combina-
tion of phenomena; oxygen unites with the substance which is burning,
caloric is disengaged from it; affinity is the cause of these chemical phe-
nomena, as attraction is the cause of the phenomena of Astronomy, and
in the same manner as the sensibility and contractility of living and or-
ganized bodies are the primary causes of all the phenomena which such
bodies exhibit — phenomena, which in their union and aggregate succes-
sion constitute life.

The false notions which have been entertained on the subject of life, and
the vague definitions which have been given of it, are to be accounted for,
by considering that physiologists, instead of regarding life as a simplere-
sult have mistaken it for the properties of life. These last are causes;
the first is merely an effect, more or less complex : and, as the spring of
a watch, or rather the elasticity of that spring, determines by the mere
action of the wheels, the motion of the hands, and all the phenomena of
which the machine is capable; so the vital properties acting by the or-
gans produce alithose effects, which in their combination constitute life.t
These effects are more or less numerous, according to the number of the
organs; they become more rapid too in their succession, and life more ac-
tive, with the increase of energy in the vital properties ; precisely as the
motions of a watch become more complicated, stronger or quicker, ac-
cording to the greater tension of the spring, or the increased number of
the wheels. Sensibility and contractility, are to be ranked amorg primary
causes, of whose existence and laws we acquire a knowledp^froni obser-
vation, but whose essence eludesour investigation^, and^'dl probably re-
main for ever beyond its reach.

§ I. OF NATURAL BEINGS.

The vast domain of nature is divided between two classes of beings.
Inorganic beings, possessing merely the common properties of matter;
organic and living beings, obeyingparticular laws, though subjected to the
general laws which regulate the universe. Each of these two grand di-
visions is naturally divided into t\no classes; we meet with inorganic bo-
dies under the form of elementary substances', simple and not capable of

* Anatomy is the science of organization,
-f See Appendix, Note A.

* It would be wrong to infer, from our ignorance of the nature of the vital proper-
ties, that physiology is'an uncertain Science. Its certainty in that point of view, 5^ equal
to that of other parts of natural philosophy. The chemist, who explains all his com-
binations by referring them to the principle of affinity, and the astronomer, who finds in
attraction the cauee that rules the universe, are absolutely ignorant of the uature of
those properties. — Authors Note.

B

10

analysis; or else under the form of 'mixed substances, compound, and ad-
mitting of decomposition. Thus, too, organized beings exist under
two very different forms of life, which distinguish them into vegetables
and animals.

The first general conception with which we ought to enter upon this
comprehensive study of nature, is the mutual dependence of those beings,
which, in their co-ordinate whole, compose the system of nature; a de-
pendence which requires for each the simultaneous existence of all. Thus
a vegetable derives its nourishment from inorganic bodies*, and alters
their inert substance, which is unfit for the food of animals, unless it has
previously undergone the influence of vegetable life.

§ II. OF THE ELEMENTS OF BODIES.

Another consideration, of equal importance with the former, is the con-
vertibility of all those substances so different from one another, and their
capacity of being reduced to a small number of simple substances, called
elements. The ancient doctrine of Aristotle, relative to the four elements,
still prevailed in the schools, with a few modifications, which it had re-
ceived from the chemists, when the " Pneumatistsf" demonstrated by
their beautiful experiments, that three, at least, of these pretended prin-
ciples of bodies, air, water, and earth, far from being simple substances,
were evidently formed by the union and combination of several others ;
that atmospherical air, for example, far from being an homogeneous fluid,
was composed of many different gazes, and that in its purest state, it con-
tains at least two very distinct principles, oxygen and azote; that water
Is a compound of oxygen and hydrogen, and that earth contains clay,
lime, silex. See.

We have seen added in the present day, to the number of the elements
or simple substances, several which were not considered as such, at the
tim^when natural philosophers, misled by erroneous metaphysical doc-
trines, Uad created out of their imagination?, beings of the existence of
which they could find no proof. There is every reason to believe, that the
number of substances not admitting of decomposition, limited at present
to forty-four, ms,y hereafter be increased or diminished, by the discovery
of new principles \\\ simple substances, or of new elements in compound
bodies, which have hitherto eluded the investigation of chemists. What-
ever may be the success ^f their inquiries, of which it is impossible to
foresee the results, or to fix the limits, there is reason to believe, that it

* MJBBEL, in his treatise on Vegetable Anftomy and Physiology, observes, " that
plants have the power of deriving1 nourishment/from, inorganic matter, which is not the
case with animals, who feed on animals and vegetables, or on both; but are never nou-
rished on earths, salts and airs." Richerand las adopted the plausible opinion of Mir-
bel. Farther inquiry might, however, have shown them that « earths and salts" furnish
as little direct nourishment to plants as to animals. Indeed it may be observed, that the
vegetable kingdom derives the chief part of its iood from dead animal and vegetable
matters — which, although they contain both " earths and salts" cannot be either rank-
ed under these substances, or even classed with them. — Copland.

j This is the name given to the school of modern chemistry, because it originated
from the discoveries made relative to the nature of air and elastic fluids. It must be
acknowledged, to the credit of metaphysics, that the old errors were forsaken, only at
the period when chemists were thoroughly convinced of this truth, that every ide'a is
obtained through the medium of the senses, and that nothing is to be admitted* beyond
what they demonstrate in actual experiment. — Authors Mtc,

II

will ever be denied us, to arrive at a knowledge of the true elements oi
bodies, and that many of those substances, which the imperfection of our
means of decomposition or analysis obliges us to consider as such, are
frequently compound substances, and subject to their laws.

After what has been stated on the elements or constituent principles of
substances, let us now see in what manner the combination of these ele-
ments gives existence to all beings, and what are the general differences
existing among the great classes into which they are divided.

§ III. DIFFERENCES BETWEEN ORGANIZED AND INOR-
GANIZED BODIES.

Much attention has been bestowed of late on the difference which exists
between organized and inorganized bodies. The latter have been observ-
ed to be very different from those which are endowed with life, in the ho-
mogeneous nature of their substance, in the complete independence of
their molecules, each of which, according to the observation of Kant, has
in itself causes to account for its peculiar mode of existence, in that pow-
er of resisting decomposition which they owe to the simplicity of their
structure, and in the absence of those peculiar powers which free organic
bodies from the absolute dominion of physical laws. The characters
which distinguish organized beings from inorganized substances, are, the
multiplicity, and volatility of their elements, the necessary union of flu-
ids and,solids, the nutrition and developement from the diffusive combina-
tion, while the growth of inanimate bodies takes place from the mere
juxtaposition of particles, theorigin of living bodies in generation, their
destruction in deathf. We are about to enter into a detail of those cha-
racters, to appreciate all their differences, for knowledge is to be acquir-
ed only by comparison; and the greater our accuracy in comparing, the
more precise and extensive-will be the knowledge we obtain. Several mo-
dern authors have proved, that it is impossible to obtain an accurate idea
of life, except by comparing those bodies which are endowed with it,
with those in which life has never existed, or has ceased to exist. This
comparison, I hope, will be fruitful in interesting results, and will furnish

* The subjoined table by Magendie, displays very satisfactorily the most perceptible
differences existing between the two great classes of beings. — Godman.

INORGANIC BODIES.

Form. — Angular. Volume indeterminate.

Composition. — Sometimes simple. Rarely formed of more than three elements. Con-
stant. Each part can exist independent of the rest. Capable of decomposition and
recomposition.

Laias governing them. — Entirely submissive to the laws of attraction and chemical
affinity.

LIVING ORGANIZED BODIES.

Form. — Rounded. Volume determinate.

Composition.— Never simple. Having at least four elements, frequently eight or ten.
Variable. Each part, more or less, dependent on the rest. Capable of decomposition,
but not of recomposition.

Laws governing them. — Partially submissive to the law* of attraction and chemical
affinity. Partly controuled by an unknown power.

Of living bodies there are two classes.

Vegetables — Which are fixed to the soil. Have carbon as the chief base of their com-
position. Composed of four or five elements. Receive their aliment ready prepared
from around ttiem.

12

several useful considerations, immediately applicable to the knowledge
of man.

The first remarkable difference between organized and inorganized
bodies, is to be found in the homogeneousness of the latter, and the com-
pound nature of the former. Let a block of marble be broken, each
piece will be perfectly similar to the rest, there will be no differences
among- them, but such as relate to size or shape. Break down the frag-
ments, each grain will contain particles of carbonate of lime, which will
be throughout the same. On the other hand, the division of a vegetable
or an animal, shows parts heterogeneous or dissimilar. In different
parts there will be found muscles, bones, arteries, blossoms, leaves,
bark, pith, Sec.

Organized beings cannot live or exist in their natural condition, unless
solids and liquids enter at once into their composition. The co-existence
of these two elements is necessary; and living bodies always contain a
liquid mass more or less considerable, and incessantly agitated by the
motion of the solid and living parts. It is in fact impossible to conceive
life existing, without a complicated combination of solids and fluids ; and
xvithout admitting in the former, the faculty of being affected by impressions
from the latter, and the power of acting in consequence of those impres-
sions. The water which penetrates into mineral substances, does not
form a necessary part of them, and one cannot adduce in proof of the
existence of liquids in that class of substances, the water of crystalliza-
tion, though intimately combined, and rendered solid in the crystallized
substances.

These inorganic and homogeneous substances, formed of particles simi-
lar to one another, when resolved by decomposition into their last ele-
ments, possess a great simplicity of inward nature. Among them are
ranked all the substances which do not admit of analysis; the mineral
compounds are often binary, as the greater part of saline substances;
sometimes they are ternary, but seldom quaternary; while the most sim-
ple vegetable contains at least three constituent principles, oxygen, hy-
drogen, and carbon, and no being possessed of life, consists of less than
four, oxygen, hydrogen, carbon and azote. In the degree of composition,
nature appears therefore to rise in gradations, from the mineral to the
vegetable, and from the latter to the animal kingdom. The complicated
nature of die latter, and the multiplicity of their elements account for their
tendency to alteration. Minerals are not subject to change, unless they
are acted upon by external causes. Endowed with a vis inertiae, they
continue in one. condition without change. The state of organized bodies
is incessantly varying. Their internal parts contain an active laboratory,
in which a number of instruments are constantly transforming into their
own substance, nutritious particles. Besides that tendency to alteration
in living animals and vegetables, when deprived of life, they become de-
composed, by a process of fermentation, which begins in their internal
parts, and by which their nature is changed in proportion to the com-
plication of iheir structure, and the greater number and volatility of their
constituent principles.

All the parts of a living body, whether of an animal or a vegetable,

Jlnimals — Have the power of locomotion. Have azote for the base of their composi-
tion. Often composed of eight or ten elements. Are forced to act on their aliment to
fit it for nourishing1 them. -

13

have a natural tendency to a common object, the preservation of the in-
dividual and of the species: each of the organs, though provided for a
peculiar action, concurs in this object;- and life in general, or life proper-
ly so called, is the result of that series of concurring and harmonic actions.
On the contrary, each part of an inorganic mass is independent of the
other parts, to which it is united, only by the force or affinity of aggrega-
tion. When such a part is separated from the rest, it maintains all its
characteristic properties, and differs only by its size from the mass to
which it belongs.

Among animals and vegetables, all the individuals of the same class
appear to have been formed after the same model; their parts are equas
in number, and resemble each other in colour; their differences are slight
and evanescent. The forms peculiar to organized beings are therefore
invariably determined, and when nature departs from them, she never
does so, to such a degree, as in the shapes of minerals. The veins of
mines are never precisely alike, as the leaves of vegetables or the limbs
of animals. Crystals formed from similar substances, assume very dif-
ferent shapes, equally distinct and precise. Carbonate of lime, for ex-
ample, assumes according to circximstances the shape of a rhomboid, that
of a six-sided regular prism, that of a solid, terminated by twelve scalene
triangles, that of a different dodecahedron with pentagonal faces, S&c. as
may be seen at large in the writings of Hiiuy.

A powerful inward cause seems to arrange the constituent parts of ani-
mal and vegetable bodies, by a determinate rule, in such a manner that
they present a surface, more or less completely rounded. Minerals often
take their form from external bodies, and when an especial force assigns
it to them, as in crystals, their surfaces are flat and angular. When the
crystallization is disturbed, and the molecules of the crystals are driven
tumultuously together, the geometrical form is impaired, the parts are
rounded which would have been terminated by angles, if a slow and tran-
quil crystallization had allowed of regular aggregation; and as Hauy
has remarked, these waving outlines, these roundings, so frequent in ve-
getables and plants, where they belong to beauty of form, are, in mine-
rals, indication of defects. True beauty, in these beings, is characterized
by the straight line, and it is on good grounds that Rome de Lisle* has
said of this sort of line, that it seems to have an especial determination
to the mineral kingdom.

Amongst all the characteristics which distinguish the two great divi-
sions of natural bodies, the most absolute, and the most palpable, is that:
which is drawn from the manner of growth and of nourishment. Inor-
ganic bodies grow only by accretion, that is, by the accession of new lay-
ers to their surface, whilst the organic, in virtue of its vital powers, re-
ceives into intimate combination, and is penetrated and pervaded, by the
substance it assimilates to itself. In animals and plants, nutrition is the
effect of an internal mechanism : their growth is a developement from
within. In minerals, on the contrary, growth cannot claim the name of
developement: it goes on externally, by successive addition of new lay-
ers; it is the same being, assuming other dimensions, whilst the organic
body is renewed in its growthf.

* Christallographie. Tom. I. p. 94.

f The organic body, is " renewed" by the absorption of the old and the deposition of
new matter, while the inorganic always retains the same matter internally, and only
grows externally, by superposition. — Godman.

14

Living bodies spring from a germ, which at first, was part of another
being, from which it detaches itself, for the sake of its own developement
and growth. From the first, they are already aggregates. Inorganic
bodies have no germ : they are made up of distinct parts brought toge-
ther; they have no birth, but a multitude of molecules, collecting into
one, compose masses of various bulk and figure.

Organized bodies alone can die; all have a duration, determined by
their own nature ; and this duration is not like that of minerals, propor-
tioned' to the bulk and density : for if man has not the life of the oak,
whose substance much exceeds his in density, neither does he equal the
life of many animals, such as fishes, whose flesh is of inferior consist-
ence to his own: and he lives longer than the large quadrupeds, though
his bulk is less.

Finally, inorganic are essentially distinguished from organic bodies, by

the want of these peculiar powers or properties of living nature: powers,

'Which uphold the. equilibrium of the whole system of nature, as I shall

explain more at large, when I have considered the differences that mark

i the two divisions of the organic kingdom, vegetables and animals.

§ IV. DIFFERENCES BETWEEN VEGETABLES AND ANI-
MALS.

These are much fewer, less absolute, and therefore more difficult to es-
tablish. There is. in fact, very little difference between a zoophyte, and
a plant, and there is a much wider difference in their internal oaconomy,
between man, who stands at the height of the animal scale, and the poly-
pus on its lowest line, than between the polypus and a plant. There lies
between organized and inorganic bodies, a space, which isnot to be filled
up by figured stones, nor by lithophytes, nor by crystals, in which some
naturalists have thought they saw a beginning of organization. Whilst,
at the extremity of the animal chain, are found beings, fixed, like plants,
on the spot of their birth, sensitive and contractile, like the sensitive and
some other plants, and reproduced like them from slips. Yet we are
able to state some differences, sufficiently marked, to assign to the ve-
getable kind a character of their own, which will not suit the individuals
of either of the other kingdoms.

Their nature, more complex than that of minerals, is Jess so than that
of animals: the proportion of the solids to the liquids, is greater than in
these last : accordingly they retain, long after death, their form and bulk,
only that they grow lighter. The solids are, in man, nearly a sixth of
the whole body : his carcase, remains decomposed by putrefaction, a lit-
tle earth, arid a light skeleton, when the ground and the air have drawn
from it all its juices. A tree, on the contrary, is more than three parts
of its substance, solid wood. It has been dead for ages, and yet in our
buildings, it preserves its form and size, though by drying it has lost a
little of its weight.

Their constituent principles, as they are less in number, are also less
diffusable. In fact, azote, which is predominant in animal substances, is a
gaseous and volatile principle, whilst carbon, the base of vegetable
substance, is fixed and solid. This circumstance, added to the smaller
quantity of their liquids, explains the long duration after death, of ve-
getable substances.

15

But of all the characteristics which have been employed in estabteih-
ing the limits of animal and vegetable nature, there is one quite sufficient
to distinguish these two great classes of beings, but which has not been
allowed the weight it deserves.

The zoophyte, which, fixed to a rocky habitation, cfcnnot change its
place, is confined to partial movements, that certain plJnts possess, and
besides, has not that sensitive unity, so remarked in man, and in the ani-
mals who nearest resemble him in their organization: the zoophyte,
whose name indicates an animal-plant, is totally separated from all be-
ings of the vegetable kingdom, by the existence of a cavity, in which ali-
mentary digestion is carried on, a cavity by the surface of which is effected
an absorption, an imbibition, far more active than that which takes place by
the external surface of the body. From this shapeless animal, up to raan?
nutrition is effected by two surfaces, and especially the internal, whilst
in the plant, nutrition, or rather the absorption of nutritive principles, is
only by the external surface*.

Every animal may be considered, in extreme abstraction, as a nutritive
tube, open at the extremities!; the whole existence of the polypus seems
reduced to the act of nutrition, as its whole substance is employed in the
formation of an alimentary tube, of which the soft parietes, extremely
sensible and contractile, are busied in appropriating to themselves, by a
sort of absorption, the substances which are brought into it. From the
worm up to man, the alimentary canal is a long tube, open at the extre-
mities; at first, only of the length of the body of the animal, not bent at
all in passing from the head to the tail, and carried on towards the mouth,
and towards the anus, with the external covering of the body, but soon
returning upon itself, and stretching out into length, far beyond that of
the body which contains it.

It is in the thickness of the pari0tes of this animated tube, betwixt the
mucous membrane that lines it inwardly, and the skin with which this
membrane is continuous, that all the organs are placed, which serve for
the transmission and elaboration of fluids, together with the nerves, the
muscles, in short, all that serves for the carrying on of life. As we rise,
from the white-blooded animals, to the red and cold-blooded, from these
to the warm-blooded, and irom these to man, we see a progressive multi-
plication of the organs that are contained within the thickness of the pa-
rietes of the canal: — If we follow, on the other hand, the descending scale,
v/e see this structure gradually simplified, till we arrive at last at the
polypus, and find in it only the essential part of animal existence. The
simplicity of its organization is such, that it may be turned inside out,
and the external be made the internal surface; the phenomena of nutri-
tion, which are the whole life of the animal, go on, from the close ana-
logy between the two surfaces; unlike to man and the greater part of
animals, in whom the skin and the mucous membranes, though growing
into e4k.h other, though linked by close sympathies, are far from possess-

* This most prominent characteristic of animal organization was lirst pointed out by
Boerhaave, anu afterwards insisted on by Dr. Alston of Edinburgh, and recently by Mr.
A. T. Thomson, in his excellent work on the Elements of Botanv. — Copland.

f Lacepzde, Histoire Naturelle des Poissons, torn 1. There may be brought against
ibis principle, the instance of some zoophytes, such as sponges, &c.; but do these bo-
dies really belong to the animal kingdom ? and should not we be warranted in rejecting1
them, by the want of the alimentary cavity, the essential characteristic of animal exist-
in ce ? — Author's Jiote-

16

ing a complete analogy of structure, or a capacity for the interchange
of functions,

Man, then, and the whole animal kind, carry about within themselves,
the supply of their subsistence; and absorption, by an inward surface, is
their distinguishing characteristic. It is inaccurate to ascribe to Boer-
haave the comparison of the digestive system of animals, to the soil in
\vhich plants suck up the juices that feed them, and the chylous vessels,
to real internal roots. I find the same thought well expressed* in the
work on humours, which, justly or falsely, bears the name of Hippo-
crates. Q?iemadmodum terrx arboribus, ita animalibus ventriculus.

The digestive tube, that essential part of every animal, is the part of
which the existence and action are the most independent of the concur-
rence of the other organs, and to which the properties of life seem to ad-
her;, if one may say so, with most force. Hallerf who has made so many
and such interesting inquiries into the contractile power of the muscular
orgins, examining them under the two-fold relation of their irritability,
as it is more or less lively, or more or less lasting, looks on the heart, as
the one in which these two conditions are found in the highest combina-
tion. He gives the second place to the intestines, the stomach, the blad-
der, the uterus, and the diaphragm, and, after these, all the muscles un-
der the command of the will. I had at first admitted, with every other
writer, this classification of the contractile parts; but more than a hun-
dred experiments on living animals have satisfied me, that the intestines
are always the last part in which the traces of life may be discovered.
Whatever may be the sort of death by which they are destroyed, peri-
staltic motions, undulations, are still continued in this canal, while the
heart has already ceased to beat, and the rest of the body is all an inani-
mate mass. Mr. Jurine had already observed on the pulex monoculus,
that, of all the parts of the body of this little white-blooded animal, the
intestines were the last to die.

If the intestinal tube be the ultimum moriens, if it be the last organ in
which life lingers and goes out, it is to it we ought to direct, in prefer-
ence, the stimulants that are capable of recalling life incase of asphyxia. I
think that, after the blowing of pure air into the lungs, the means that
ought next to be attended to is the injection of acrid and irritating clys-
ters, thrown in with force. The large intestines are connected with the
diaphragm by a close sympathy, as is proved by the phenomena of fecal
evacuation ; the irritation of them is the surest means of accelerating; it;
and this irritation is the easier, as the alimentary canal is the last part

that is forsaken bv life.

•

§ V. OF LIFE4

After having thus laid down, between organic bodies and organized
living beings, and again between animal and vegetable nature, aHine of

* An error. The words are, * UO-TT^ TOM ftvfyta-iv H y*, xru> TVO-IV faourtv H F A2THP, XM
Tettu xti d-t£t/.Aivu x*i 4u;ty>' Which is thus rendered by the accurateFcissius, « ut se habet
terra in arboribus ita in animantibus venter al'.t calet'acit et refrigerat.' As the earth does
to trees, so the belly supports, heats, and cools animals. Though the book on the 'hu-
mours,' is received as genuine by Galen and Erotian, it must be remembered that com-
mentators have always been able to make HIPPOCRATES support their notions. In the
sentence quoted, all the viscera of* the abdomen are referred to, in general terms;
x«,\« is the word used, when the particular organ, the stomach, is meant. — Godma-n.

f Opera jnhiorat 3 vol. 4to. ± Sec Appendix, Note A.

17

demarcation that cannot be mistaken, let us endeavour to exalt ourselves
to the conception of Life ; and for accuracy of thought, let us, in some sort,
analyse it, by studying it in all the beings of nature that are endowed with
it. In this study, of which I may be allowed to state, in advance, the re-
sults, we shall see life composed at first of a small number of phenomena,
simple as the apparatus to which it i» given in charge; but soon extend-
ing itself as its organs or instruments are multiplied, and as the whole or-
ganic machine becomes more complex; the properties which character-
ize it and bear witness of its presence, at first obscure, becoming more
and more manifest, increasing in number as in developement and energy ;
the field of existence enlarging, as from the lower beings we re-ascend to
man, who, of all, is the most perfect; and observe, that by this term of
perfection, it is simply meant that the living beings to which we apply
it, possessed of more means, present also more numerous results and
multiply the acts of their existence; for in this wonderful order of the
universe, every being is perfect in itself, each being is constructed most
favourably for the purpose it is to fulfil; and all is equally admirable, in
living and animated nature, from the lowest vegetation to the sublimity
of thought.

What does this plant present to us' that springs up, and grows, and
dies every year ? A being whose existence is limited to the phenomena of
nutrition and reproduction ; a machine constructed of a multitude of ves-
sels, straight or winding, capillary tubes, through which the sap is filtra-
ted and other juices necessary to vegetation ; these vegetable liquors as-
cend, generally, from the roots, where their materials are taken in, to the
summit, where what remains from nutrition is evaporated by the leaves,
and what the plant could not assimilate to itself is thrown off in transuda-
tion. Two properties direct the action of this small number of functions:
a latent and faint sensibility, in virtue of which, each vessel, every part
of the plant, is affected in its own way by the fluids with which it is in
contact; a contractility as little apparent, though the results prove irre-
fragably its existence; a contractility, in virtue of which, the vessels,
sensible to the impression of liquids, close or dilate themselves, to effect
their transmission and elaboration. The organs allotted to reproduction,
animate, for a moment, this exhibition : more sensible, more irritable,
they are visibly in action; the stamina, or male organs, bow themselves,
over the female organ, the pistils, shake on the stigma their fertilizing
dust, then straighten, retire from it, and die with the flower, which is
succeeded by the seed or fruit.

This plant, divided into many parts, which are set in the earth with
suitable precautions, is reproduced and multiplied by slips, which proves
that these parts are little enough dependent on each other; that each of
them contains the set of organs necessary to life, and can exist alone.
The different parts of a plant can live separately, because life, its simpler
organs and properties are diffused more equably, more uniformly, than in
animals like man, and its phenomena are connected in a less strict and
absolute dependence. I myself have witnessed a very curious fact, which
confirms what I have said*. A vine, trained against the eastern wall of

* Vegetable life, compared in its means and in its results, to the life of animals, would
throw the greatest light on many phenomena which it is still difficult for us to conceive
and to exp'ain. The treatment of disease in plants', for which as much would be grained

18

a forge, shot into the building a few branches. These branches, which
entered by straight enough passages, were covered with leaves in the
middle of the hardest winters ; and this premature but partial vegetation
went through all its periods, and was already in flower when the part re-
mained without was beginning to bud with the spring.

If we pass from the plant to th« polypus, which forms the last link of
the animal chain, we find a tube of soft substance, sensible and contractile
in all its parts, a life and organization at least as simple as that of the
plant. The vessels which carry the liquids, the contractile fibres, the
trachese, which give access to the atmospheric air, are no longer distinct-
ly to be traced in this almost homogeneous substance. There is no or-
gan especially allotted to the reproduction of the kind. Moisture oozes
from the internal surface of the tube, softens and digests the aliments
which it finds there ; the whole mass draws in nourishment from it ; the
tube then spontaneously contracts, and casts out the residue of digestion.
The mutual independence of parts is absolute and perfect: cut the crea-
ture into many pieces, it is reproduced in every piece; for each becomes
a new polypus, organized and living, like that to which it originally be-
longed. These gemmiparous animals enjoy, in a higher degree than plants,
the faculties of feeling and of self-motion; their substance dilates and
lengthens, and contracts, according to the impressions they receive.—-
Nevertheless, these spontaneous movements do not suppose, any more
than those of the mimosa, the existence of reflection and will ; like those
of a muscle detached from the thigh of a frog and exposed to galvanic
excitation, they spring from an impression which does not extend beyond
the part that feels it, and in which sensibility and contractility are blend-
ed and lost in each other.

From this first degree of the animal scale, let us now ascend to worms.
We have no longer a mere animated pulp shaped into an alimentary tube;
parcels of contractile or muscular fibres, a vessel divided by several con-
strictions into a series of vesicles, which empty themselves one into ano-
ther, by a movement of contraction that begins from the head, or the en-
trance of the alimentary canal, and proceeds towards the tail, which an-
swers to the anus, a vessel from which, in all probability, are sent out
lateral ramifications,t a spinal mai row equally knotted, or composed of a

by these inquiries, is almost entirely surgical. When, to make vegetation more fruitful,
the gardener prunes a luxuriant branch ; when the peasants of the Cervennes, as M.
Chaptal has observe*!, burn the inside of their chesnut trees to stop the progress of a
destructive caries ; when the actual cautery is applied to the really ichorous and foul ul-
cers of many trees, &c. it is to the organs of inward life, (or that which carries on the
process of assimilation) the only life of vegetables, that surgery is applied; while on
the contrary, in man and animals, it is to the derangement of the external organs that
the remedy is directed. I shall conclude this note with an observation on the wounds
of plants. Like those of the human body, they are much less dangerous when their
surface is smooth, than when their edges are hacked, torn, or bruised. Tre'es felled
with the saw will hardly shoot up from the stool, which always furnishes a better growth
when an axe has been* employed. The saw lacerates the 'vegetable texture, and its
violent and distressing action on the fibres extending towards the roots, affects, more
or less, the organization. The uneven surface of a tree felled in this manner, holds
wet, as injurious to the trunk, which it rots, as a too great quantity of pus, which bathes
constantly the surface of a wound, checks the process of granulation, and resists cica-
trization.— Author's J\'ote.

-j- This class of animals cannot be considered to possess a spinal marrow. The series
of ganglions which they exhibit, is merely the vertebral ganglia of the sympathetic
nerve. — Copland.

19

chain of ganglions*, stigmas, and tracheae, analogous to the respiratory
organs of plants, and in some, even gills : all shows clearly an organiza-
tion further advanced, and more perfect : sensibility and contractility are
more distinct; the motions are no longer absolutely automatic : there are
some which seem to suppose a choice. The worm, too, may be divided
into many pieces ; each will become a separate and perfect worm; a head
and tail growing to eachf; but this division has its term, beyond which
there is no longer complete regeneration. It cannot, therefore, be push-
ed so far as in the polypi. The substance of the* worm being formed of
elements more dissimilar, it may be that too smal] a portion does not con-
tain all that is necessary to constitute the animal.

The crustaceous tribes, and among them the lobster, discovers a more
complex apparatus of organization. Here you will find distinct muscles,
an external articulated skeleton, of which the separate parts are move-
able upon each other, distinct nerves, a spinal marrow with bulgings, but,
above all, a brain and a heart. These two organs, though imperfect, as-
sign the animal to an order much above that of worms. The first be-
comes the seat of a sort of intelligence ; and the lobster acts evidently
under impulses of will, when attracted by a smell, it pursues a distant
prey, or when it flies a danger discovered to it by its eyes. There are
viscera accompanying the intestinal tube, which give out to it liquids
that concur in alimentary digestion. Sensibility and contractility pre-
sent each two shades : in fact, the parts of the animal are obedient to the
internal stimuli, feel the impression of fluids, and contract to impel them ;
on the other hand, by its nerves and locomotive muscles, the lobster
places itself in connection with the objects that surround it. The phe-
nomena of life are linked together by a strict necessity: it is no longer
possible to separate the creature into two parts, of which each may con-
tinue to live; there are but few parts you may cut off without injury,
while you spare the central foci of life. So, if you take off a claw, you
observe soon a little granulation, which swells and is developed, and
which, soft at first, is soon clothed in a calcareous covering like that
"which encloses the rest of its body. This partial regeneration is fre-
quently to be seen.

If from white-blooded animals we go on to the red and cold-blooded,
such as fishes and reptiles, we see this power of reproduction becoming
more and more limited, and life more involved in organization. In fact,
if you cut off a part of the body of a fish, the tail of a serpent, or the foot
of a frog, the separated parts are either not supplied at all, or very im-
perfectly reproduced. All these creatures maintain, with the medium in
•which they live, relations of more strict dependence. Gills in these, lungs
in others, are added to a heart, nor are less essential to life. However,
the action of these chief organs is not so frequent, nor of momentary ne-
cessity for the continuance of life. The serpent passes long winters, tor-
pid with cold, in holes where he has no air, without breathing, without any
motion of life, and in all appearance dead. These creatures, like all rep-
tiles, are able to breathe only at long intervals, and to suspend, for a
time, the admission of air, without risking their existence. Here the

* Appendix, Note B.

f This may be observed tn several of the intestinal worms. It ought to be kept in
recollection during our endeavours to remove them from the body— Copland,

£0

vital powers are distinct and strong, and differ from those of the more
perfect animals and of man, by very slight shades: thehean and the ves-
sels of the fish feel and act with him, without his consciousness. Further,
he has senses, nerves, and a brain, from which he has intimation of what-
ever can affect him; muscles and hard parts, by the action of which he
moves, and changes his place, adapting himself to the relations that
subsist between the substances around him and his own peculiar mode of
existence.

We are come, ai last, to the red and warm-blooded animals, at the head
of which are the manuiiiferse and man. They are entirely alike, save
some slight differences in the less essential organs. There is none that
has not the vertebral column, four limbs, a brain which fills, exactly, the
cavity of the skull, a spinal marrow, nerves of two sorts, five senses, mus-
cles, partly obedient to the will, partly independent in their action; add
to these a long digestive tube coiled upon itself, furnished at its mouth
with agents of saliva and mastication : vessels and lymphatic glands, ar-
teries and veins, a heart with two auricles, and two ventricles, tabular
lungs, which must act incessantly in impregnating the blood, that passes
through them, with the vital part of the atmosphere*, which if it fail, life
is suspended or gone. None of their organs live, but while they partake
in the general action of system, and while they are under the influ-
ence of the heart. All die, irrecoverably, when they are parted from the
body of the animal, and are in no way replaced ; whatever some physio-
logists may have said on pretended regeneration of the nerves and some
other pans.

Every thing that is important to life, is to be found in these animals;
and as the most essential organs are within, and concealed in deep cavi-
ties, a celebrated naturalist was correct in saying, that all animals are es-
sentially the same, and that their differences are in their external parts,
and chiefly to be observed in their coverings and in their extremities.

The human body, consisting of a collection of liquids and solids, con-
tains of the former, about five-sixths of its weight. This proportion of
the liquids to the solids, may, at first sight, appear to you beyond the
the truth; but consider the excessive decrease of size of a dried limb;
the glutseus maxinnfs, for example, becomes, by drying, no thicker than
a sheet of paper. The liquids which constitute the greatest weight of
the body, exist before the solids; for the embryo, which is at first in a
gelatinous state, may be considered as fluid ; besides, it is from a liquid
that all the organs receive their nourishment and repair their wastes.
The solids, formed from the liquids, return to their former state, when,
having for a sufficient length of time, formed a part of the animal, they
become decomposed by the nutritive process. Even from this slight
view of the subject, fluidity is seen to be essential to living matter, since
the solids are uniformly formed from the fluids, and eventually return to
their former state. Solidity is then only a transient condition and an ac-
cidental state of organized and living matter, and this circumstance
affords to the humoral pa,thologists ample opportunities of embarrassing
their opponents with many objections not easily answered. Water forms
the principal part and the principal vehicle of all the animal fluids, it con-

* Late experiments have shown that a different process takes place in the lungs. See
CHAPTER or RESPIRATION.

tains saline substances in a state of solution, and even animal matter it-
self is found in it fluid, and that in three different conditions, under the
form of gelatine, of albumine, or fibrine. The first of these substances,
solidified, forms the basis of ail the organs of a white colour, to which
the ancients gave the name of spermatic organs, such as the tendons, the
aponeurosis, the cellular tissue, and the membranes. Albumine exists in
abundance in almost all the humours; the fibrine of the blood is the ce-
ment which is employed in repairing the waste of a system of organs,
which, in point of bulk, hold the first rank among the constituent parts
of the human body — I mean the muscular system. The chemists sus-
pect, and not without reason, that the animal matter passes successively
through the different states of gelatine, albumine, and fibrine $ that these
different changes depend upoji the progressive animalization of the ani-
mal matter, which is at first gelatinous, a hydro-carbonous oxycle, con-
taining no azote, and acidifiable by fermentation, becomes more closely
combined with oxygen, takes up azote, so as to become albumen, sub-
ject to putrefaction, and finally fibrine, by a super-addition of the same
principles.

The solid parts are formed into different systems, to each of which is
intrusted the exercise of a function of a certain degree of importance.
Limiting the term organic apparatus, or system, to a combination of
parts which concur in the same uses, we reckon ten, viz.1 — the digestive ap-
paratus, consisting essentially of the canal which extends from the mouth
to the anus; the absorbent, or lymphatic system, which is formed of the
vessels or glands of that name: the circulatory system, which consists of
an union of the heart, the veins, the arteries, and the capillary vessels ; the
respiratory, or pulmonary system ; the glandular^ or secretory system; the
sensitive system, including the organs of sense, the brain, and spinal mar-
row; the muscular system, or that of motion, including not only the mus-
cles, but their tendons and aponeuroses; the osseous system, including
the appendages of the bones, the cartilages, the ligaments, and the syno-
vial capsules, the vocal system, and the sexual, or generative system, dif-
ferent in the two sexes. Each of these organic systems contains in its
structure several simple tissues, or u similar parts," as the ancients called
them : — these tissues in man may be enumerated "es follows, cellular tis-
sue, nervous tissue, muscular tissue, besides that horny substance which con-
stitutes the basis of the epidermis, the nails and the hair*.

* One of the oldest divisions of the primary textures of the body, and one winch near-
ly coincides with that given by the author, acknowledges three tissues only, viz • the
cellular, nervous, and muscular. This arrangement has been adopted by the majority of
physiologists since the time of Ilaller. It may be shown tht all the textures and organs
of the body result either from the various distribution of these primary tissues ; or from
the cellular only, in consequence of a greater condensation of its substance, or approxi-
mation of the molecules of matter entering into its constitution, and owing to a deposi-
tion of earthy substance between its interstices, sis in the bones. It may/ however, be
a matter of doubt whether the muscular texture does not arise from the union of the
cellular tissue with the nervous substance ; the former combining1 with the h'brillae of the
organic or ganglial nerves to form the muscular fibre generally, whether involuntary or
voluntary, while the latter class of muscles derives its peculiar characters and functions
from the accession of the fibrillae of voluntary nerves to the ganglial and cellular tex-
tures. If this position be allowed, the involuntary fibres will appear to result from the
combination of the cellular substance with the ganglial nerves only, the voluntary from
the union of the cellular with both the ganglial and cerebral matters composing the ex-
tremities of their ramifications ; the muscular fibre varying1 its character and phenome-

These four substances may be considered as real organic elements,
since with our means of analysis, we never can succeed in converting any
of these substances into another. The cerebral pulp is not convertible
into a horny substance, into cellular substance, or into muscular fibre,
neither can any one of these tissues ever be converted into cerebral pulp.
The bones, the cartilages, the ligaments, the tendons, the aponeuroses,
may, by long maceration, be converted into cellular substance. Muscu-
lar fibres are not subject to that alteration, nor is the nervous or cerebral
pulp : the horny substance also resists that change. Every thing, there-
fore, leads us to acknowledge these four constituent principles in our
organs.

The primitive or simple tissues, variously modified, and combined in
different quantities and in various proportions, constitute the substance
of our organs. Their number is much more considerable, according to
Bichat, whose happiest conception was the analysis of the human or-
ganization. This physiologist reckoned in the human oeconomy, no few-
er than twenty-one general or generating tissues*. But it is evident,
that this analysis is carried too far; that the tissues of which the skin
and the hair are formed, are exactly of the same nature, are analagous
in their properties, and are nourished in a similar manner ; that the cel-
lular tissne is the common basis of the osseous, cartilaginous, mucous,
serous, synovial, dermoid, &c.

It must be confessed, that this separate consideration of each organic
tissue has furnished him with new ideas, ingenious analogies, and use-
ful results, and that his " Anatomic Generate," in which those research-
es are contained, is his chief title to glory. That glory would be com-
plete, if in that book, and yet more, in his other works, he had done his

USE according as more or less of either kind of nervous substance enter into its compo-
sition. An intimate view of the mode of distribution which characterizes both class of
nerves, as well as various other considerations, support this opinion, which is calculated
to form the basis of some plausible explanations of many of the most important appear-
ances and functions of the different muscular textures.

* The following classification of the primary and compound textures nearly coincides
with that recommended by Dupuytren and Magendie :

fl. Cellular.

3. Muscular

r Arterial.

4. Vascular. . . . . . <Veinous.

£ Lymphatic.

5. Osseous.

f" Fibrous.

6. Fibrous , . . < Fibro-Cartiluginous.

£ Dei-moid.

7. Erectile.

8. Mucous.

9. Serous.
10- Synovial.
11. Glandular.

^.12. Epklermous. or Corneous. — Copland,

23

predecessors, as well as his contemporaries, the justice they had a right
to expect from him.

The simple, or elementary fibre, about which so much has been writ-
ten, may be considered as the philosopher's stone of physiologists*. In
vain has Haller himself in his pursuit of his chimera, told us, that the
elementary fibre is to the physiologist what the line is to the geometer,
and, that as all figures are formed from the latter, so are all the tissues
formed from this fibre : Fibra enim fihysiologo id est quod linea geametrae,
ex qua nempe jigurse omnes oriuntur. The mathematical line is imaginary,
and a mere abstraction of the mind, while the elementary fibre is allowed
a material or physical existence. Nothing, therefore, can make us ad-
mit the existence of a simple, elementary, or primitive fibre, since our
senses show us in the human organization, four very distinct materials.

Among the organs, whether single or combined in systems, which en-
ter into the human organization, there are some whose action is so essen-
tial to life, that with the cessation of that action, life at once becomes
extinct. These primary systems, whose action regulates that of all se-
secondary systems, are as numerous in man as in the other warm-blooded
animals. None of them can act unless the heart sends into the brain a
certain quantity of blood, vivified by the contact of atmospherical air in
the pulmonary tissue. Every serious wound of the brain or heart, every
lasting interruption to the access of blood into the former of these organs,
is invariably attended with death. The oxydation of the blood, and its
distribution into all the organs, is consequently the principal phenome-
non on which the life of man and of the most perfect beings depend.

§VI. OF THE VITAL PROPERTIES; SENSIBILITY AND
CONTRACTILITY!.

By sensibility is meant that faculty of living organs, which renders them
capable of receiving from the contact of other bodies, an impression
stronger, or fainter, that alters the order of their motions, increases or
diminishes their activity, suspends, or directs them. Contractility is that
other property by which parts excited, that is, in which sensibility has
been called into action, contract or dilate, in a word, act, and execute
motions. In the same manner, as we have not always a consciousness of
the impressions received by our organs, and as, for example, no sensa-
tion informs us of the stimulating impression by which the blood calls
the heart into action, so it is by reflexion only, that we are induced to
admit the existence of certain motions; of those, for instance, by which
the humours, when they have reached the smallest vessels, become in-

* Almost every physiologist who has written on Animal Organization has proposed a
new arrangement of the primary textures. We will only take notice of the two follow-
ing : — WALTIIER considered the different organs and compound textures to result from
the cellular or membranous, the vascular orjibroiis, and from the nervous. J. F. MECKEI.
founds his classification of organic substances on microscopic researches. He is of opi-
nion that the solids and fluids of the human body can be reduced to t~co elementary sub-
stances, the one formed by globules, the other by a coagulable matter, which, either
alone or united to the former, constitutes the living fluids, if it be in the liquid state, and
-ivc

to the solid tissues, when it assumes the concrete form. See APPENDIX,
Note C, for a more detailed account of the opinion of this eminent Anatomist. -Copland
f See APPENDIX, Note D.

24

corporalecl into the tissue of our organs*. These motions, to make
use of an ingenious comparison, resemble those of the hour-hand, com-
pared with the second-hand of a watch. The hour-hand appears motion-
less, and yet in twelve hours it describes the whole circumference of the
dial-plate, round which the other hand moves in one minute, with a mo-
tion that is visible.

In considering life through the great series of beings that possess it,
we have seen that those in which it is most limited, or rather in which it
consists of the least number of actions, and phenomena, vegetables, for
instance, and animals like the polypus, which have no brain, no distinct
nervous system, are at once endowed with sensibility and contractility in
all their parts. All living beings, all the organs which enter into their
composition, are impregnated, if we may be allowed the expression, with
these two faculties, necessarily co-existing, and which show themselves
by internal and nutritive motions, obscure, indeed, and to be distinguish-
ed only by their effects. These two faculties appear to exist in the de-
gree absolutely required for enabling the fluids that pervade all the parts
of a living body, to induce the action by which these parts are to assimi-
late such fluids. It is clear, that the two properties of feeling and of
motion are indispensable to all parts of the body. They are properties
universally diffused through organized and living matter, but they exist
withous possessing any peculiar organ or instrument of actionf. Were it
not for these two faculties, how would the different parts act on the
blood, or on the fluid which supplies its place, so as to obtain from it
the materials subservient to nutrition and the different secretions ? These
faculties are therefore given to every thing that has life — to animals,
to vegetables; to man in his waking hours, or in his most profound
sleep, to the foetus, to the child that is born, to the organs of the assimi-
lating functions, and to those which connect us with surrounding beings.
Both these faculties, obscure, and inseparable, preside over the circula-
tion of the blood, of the fluids, and, in short, over all the phenomena of
nutrition.

Though this kind of sensibility is always latent or concealed, it is other-
wise with regard to contractility, which may be sensible or otherwise.
The bone, which takes up the phosphate of lime, to which it owes its
solidity, exerts that action without our being aware of its taking place,
except by its effect : but the heart which feels the presence of the blood,
without any consciousness, on our part, of such sensation, exerts motions
that are easily perceptible, but over which we have no controul, either to
suspend or accelerate them.

Vital properties in so weak a degree, would not have been sufficient to

* If the suggestions offered, in the Note at p. 12, respecting the constitution of the
different kinds of muscular fibres, were adopted, the explanation of the properties, sen-
sibility and contractility, and the relations which they hold with the circle of vital func-
tions, wov-lu be more apparei.f and better understood. — Copland,

•f- Tiiis is an impossibility. If there be feeling and motion, a material capable affecting,
aud a power capable of moving are presupposed. If the feeling1 and motion belong- to
the fluid independent of organization, the results are merely plays of chemical affini-
ties, and the changes taking' place, mere superpositions. But the polypus is confess-
edly organized and digests, so that although we do cut it in pieces, the parts or whole
reproduced, are formed by the action of the remaining1 organization on the fluids, and
not by the fluids themselves. The feeling- and motion are attributable solely to impres-
sions made on a nervous and muscular system, however singular in its kind. — Godman.

25

the existence of man and of the animals which resemble him, obliged to
keep up multifarious intercourse with every thing that surrounds them ;
thus they enjoy a very superior kind of sensibility, by means of which the
irnpresssons which affect some of their organs are perceived, judged, and
compared. This mode of sensibility might be more properly called per-
ceptibility, or the faculty of accounting to one's self for the emotions which
are experienced. It requires a centre to which t e impressions may be
referred, and therefore it exists only in the animals which, like man, have
a brain or some organ in its stead ; so that the zoophytes and vegetables,
wanting that organ, are equally destitute of this faculty. The polypi,
and some plants, as the sensitive, perform nevertheless certain sponta-
neous motions, which seem to indicate the existence of volition, and con-
sequently of perceptibility. But these motions are the result of an im-
pression, which does not extend beyond the part in which it is experi-
enced, and in which sensibility and contractility are blended.

The almost latent sensibility of certain parts of the body, cannot be ab-
solutely compared to that of vegetable; since those organs whose sensi-
bility is so imperfect, manifest in disease a percipient sensibility, which
shows itself by acute pain, and it is even sufficient to change the stimulus
to which they are accustomed, to determine the occurrence of that phe-
nomena. Thus the stomach, on the parietes of which, the food does not
in health produce any perceptible impression, becomes the seat of very
distinct sensation and of dreadful pain, when a small quantity of poison-
ous matter is introduced into it. In like manner, we are not conscious of
the impressions excited in the parietes of the bladder or rectum, by the
collection of urme^or foecal substances, except when their contents have
become sufficiently irritating by their presence, to excite in a certain de-
gree, those irritable and sentient cavities, and to transform their obscure,
into a very distinct sensibility. Is there not reason to suspect, that our
unconsciousness, in health, of the impressions made on our organs by the
fluids which they contain, depends on our being accustomed to the sensa-
tions which they incessantly excite? so that there remains but a confused
perception, which in time disappears, and may we not, under that point
of view, compare all these organs to those of sight, hearing, smelling,
tasting, and touching, that are no longer irritable by stimulants, to which
they have long been habituated ?

Two systems of organs, very different in their uses and in their quali-
ties, enter into the composition of the human body; they are as two liv-
ing and united machines, the one, formed by the organs of sense, the
nerves, the brain, the muscles, and the bones, serves to maintain its con-
nexion with external objects: the other, destined to internal life, con-
sists in the digestive tube, and the organs of absorption, circulation,
respiration, and secretion. The organs of generation in the two sexes
form a separate class, which, as far as relates to the vital properties, par-
takes of the nature of the other two.

By the organs of sense, and the nerves which form a communication
between these organs and the brain, we are enabled to perceive or to feel
the impressions made onus by external objects : the brain, the true seat
of that relative sensibility, which might very justly be termed perceptibility
or the perceptive power, (Pott) when excited by these impressions, is able
to irradiate into the muscles the principle of motion, and to induce the
exertion of their contractility. This property, which is under the direc-
tion of the will, manifests itself by the sudden shortening of a muscle,

'D

«

which swells, hardens, and determines the motion of those parts of the
skeleton to which it is attached. The nerves and the brain are essenti-
ally the organs of these two properties, a division of the former is attend-
ee} with a loss of sentiment and voluntary motion in the parts to which
they are distributed. The other kind of sensibility is, on the contrary,
quite independent of the presence of nerves; it exists in all organs,
although all do not receive nervous,filaments. It might even be asserted,
that the cerebral nerves are not at all essential to the life of nutrition ; the
bones, the arteries, the cartilages, and several other tissues, in which no
nerves are seen to enter, are nourished equally well with the organs in
which they exist in considerable number ; the muscles themselves will
carry on their own internal osconomy, notwithstanding the division of
their nerves ; only, deprived of those means of communication with the
brain, they can no longer receive from it the principle of voluntary con-
traction; instead of that sudden, energetic, and lasting shortening, which
the will determines in them, they become merely capable of those quiver-
ings called palpitations.

The anatomist who studies the nerves with a view to ascertain their
termination, finds them all arising from the brain and spinal marrow, and
proceeding by a longer or shorter course, to the organs of motion or of
sensation; let him take his scalpel and dissect one of our limbs, the thigh,
for instance, he will see the cords parting into numerous threads, most of
which disappear in the thickness of the muscles, whilst others, after
creeping for a time about the cellular tissue, which joins the skin to the
apon eurosis, end on the inward surface of the skin, of which they com-
pose the texture, and expand into sentient papillae on its furface. The
bones, the cartilages, the ligaments, the arteries, and the veins, all those
parts whose action is not under the controul of the will, are without
them*. Nevertheless, all those parts, which, in their natural state, send
no perceptible impressions to the brain, which, when once insulated, may
be tied and cut, without any sign of pain from the animal, and whose ac-
tion the will does not controul. are yet endued with a sensibility and a
contractility, which enable them, after their own manner, to feel and to
' act, to recognize in the fluids that moisten them, what is suited to their
nourishment, and to separate that recrementitious part which has suita-
bly affected their particular mode of sensibility!.

In confining our attention then, to the consideration of a single limb,
we may easily satisfy ourselves of the existence of two modes of feeling,

* Comparatively speaking ; the nerves may be traced into bones, accompanying-
their arteries and veins, and we should with greater propriety declare that toe cannot
see them in the coats of arteries and veins, than that they do not exi.st We are unable
to conceive how such vessels can be organs of secretion, assimilation or absorption
without a nervous system of their own ; which we believe has its peculiarities and mo-
difications to suit the purposes for which it is designed. — Godman.

•f- All these parts may be considered to possess ganglial nerves ; for as these nerves
may be demonstrated on the more considerable trunks of arteries, even in the extremi-
ties, they may be supposed to accompany these vessels to their most minute ramifica-
tions and terminations, and to bestow on them the manifestations which these parts of
the vascular system evince. Such, then, being the constitution and connexion of the
arterial and capillary vessels, no texture which possess these vessels can be considered
to be destitute of this class of nerves. Those nerves that belong to the other class, or
the cerebral, may be inferred to exist, in an organ, more or less abundantly, or to be
entirely absent from it, according to the nature of the phenomena which that organ
presents. See CHAPTERS OK THE CIRCULATION, SENSATION AND MOTION.

*as of two sorts of motion 5 a sensibility in virtue of which, certain parts
can send up to the brain, the impressions they receive, to be there objects
of consciousness ; and another sensibility belonging to all organs without
exception, and all that some of them possess, which is sufficient for the
exercise of the functions ©f nutrition, and by means of which they are
evolved, and kept up in their natural state ; two kinds of contractility,
appropriated to the two different kinds of sensibility: — The one, in vir-
tue of which the muscles obedient to the will, exercise the contractions
which it determines; the other, independent of the will, manifests itself
by actions, of which we have no intimation, any more than of the im-
pressions by which they are determined.

The distinction being fairly laid down between sensibility and contrac-
tility, it is easy to understand the origin of the endless disputes of Haller
and his followers, about the parts of the body, in man and animals, which
are endowed with sensibility andt irritability. All the organs to which'
that learned physiologist has denied these properties, as bones, tendons,
membranes, cartilages, and cellular membrane, &c. possess only that
latent sensibility, and that obscure contractility, common to all living
beings, and without which, it is impossible to conceive life to exist. In
a state of health, they are utterly incapable of transmitting to the brain
perceptible impressions, and of receiving from it the principle of mani-
fest and sensible motion. It has likewise been a matter of much dispute,
whether sensibility and contractility are qualities, of nerves; if these
parts are their only instruments, and if their destruction is attended with
a loss of these two vital properties, in the parts to which they are trans-
mitted. We may answer in the affirmative, as far as relates to the sensi-
bility of perception, and the voluntary motion which is entirely subser-
vient to it, but that the existence of nerves is not at all necessary to the
exercise of the sensibility and contractility which are indispensable to
the assimilation of nutrition.

No part'of the living body is absolutely insensible, but that sensibility
of every organ is so modified, that it is not affected by the same stimuli.
Thus, the eye is insensible to sound, and the ear to light. A solution of
tartar emetic, causes no disagreeable impression to the conjunctiva;
taken into the stomach, it excites convulsive motions, while an acid from
which the stomach does not suffer, proves a cause of irritation to the con-
junctiva, and brings on a violent inflamation of the eye. In the same
manner, purgatives pass along the stomach, without producing any ef-
fect on the viscus, but they stimulate the alimentary canal. Cantharides
have a specific action on the bladder; and mercury on the salivary
glands. Eacn part feels, lives, moves, after its own way 5 in each the
vital properties appear under such shades and modifications, that they
may be looked upon as so many separate members of the same family,
concurring in one endeavour, working for a common end, consentientia
omnia. (Hipp.)

The faculty of assigning a cause to the sensation, and that of moving
by volition, which man possesses in common with all animals formed
with a distinct nervous centre, are essentially bound together. For sup-
pose a living being, furnished with locomotive organs, but without sen-
sation, placed in the midst of bodies, that every moment endanger its
existence, without any means of distinguishing them, it will hasten its
own destruction. If perceptibility could, on the other hand, exist inde-
pendently of motion, how dreadful would be the fate of such sentient be-

28 .

being, similar to the fabulous Hamadryads, who, immoveably fixed in the
trees of our forests, received, without any power to shun them, all the
blows inflicted on their rustic abode. Dreams place us sometimes in
situations which give us a just idea of their condition. A certain dan-
ger threatens our existence ; an enormous rock seems to detach itself, to
roll and precipitate itself on our frail machine ; a frightful monster
seems to pursue us, and opens a yawning mouth to ingulf us. We strug-
gle to escape this imaginary danger, to avoid or to repel it, but an irre-
sistible and unknown power, a mighty hand paralyses our efforts, and
keeps us rooted to the spot; it is a situation of horror and despair, and
we awaken overwhelmed with the uneasiness which we have suffered.

As there is no part that does not feel, in a manner peculiar to itself, so
there is no one that does not act, move, or contract, in a manner peculiar
to itself; and the parts which have been found without a power of mo-
tion analagous to muscular contractility, have remained in thaf state of
immobility, only for want of a stimulus fitted to their peculiar nature.
Some physiologists say they have excited a distinct quivering, in the me-
sentery of a frog and of a cat, by touching them after they had been pre-
viously moistened with alcohol, or muriatic acid,

In the operation for sarcocle*, I have often perceived that while with
my left hand I supported the tumour, and with a scalpel in the right, di-
vided the spermatic chord, the tunica vaginalis showed oscillatory con-
tractions. It visibly contracts in the operation for hydrocele. The in-
jection of an irritating fluid determines evident motions in the tunica
vaginalis. The osseous tissue, notwithstanding the phosphate of lime
with which it is incrusted, is susceptible of a contraction, whose effects,
though slow, are nevertheless undeniable. After teeth have been shed
or extracted, the edges of the alveolar process become thinned and
the alveolar cavities disappear. These facts appear to me to prove,
still better than all the experiments performed on living animals,
(experiments of which, by the way, the results ought nbt too con-
fidently to be applied to the oeconomy of man) what one should think
of the assertions of Haller and his followers, on the insensibility and
inirritability of the serous membranes, and of the organs of a structure
analagous to their's.

We will, at present, say nothing of the porosity, of the divisibility, of
the elasticity, and other properties which are common to living bodies and
inanimate substances. These properties are never possessed in their
whole extent, and in all their purity, if that expression may be allowed.
Their results are always influenced by the vital power, which constantly
modifies the effects which seem to depend most immediately upon a phy-
sical, chemical, or mechanical cause, or upon any other agent whatsoever.

* The contraction of the membrane, formed by the expansion of the cremaster mus-
cle, has doubtless assisted in rendering more dittinctthe appearance in question. This
effect must be particularly distinct at the moment of dividing- the spermatic chord.
The contraction of the same muscles corrugate the skin of the scrotum when tiiis part
is exposed to cold, and draw up the testicles towards the inguinal ringf. The contrac-
tility of the skin of the scrotum, has but little influence in procuring- this effect.— Jt.

f This assertion may lead to error ; the testicles are raised by the cremasters, and
this is, or may be made a voluntary action ; but the corrugation of the scrotum is inde-
pendent of the will, and is produced by a contraction directly the reverse of that effect-
ed by the cremasters, i. e. laterally, while that of the cremasters is perpendicular. —

Godman.

29

Not so with the truly vital extensibility •, which is so manifest in certain
organs, as the penis and the clitoris. When excited, they become tur-
gid and dilated by the afflux of blood, but that effect does not depend
on a peculiar property, distinct from sensibility and contractility. These
parts dilate, their tissue stretches under the action of these two proper-
ties, which would occasion the same phenomenon in all other parts, if
their structure were similar.

The same applies to caloricity, or that power inherent in all living be-
ings, of maintaining the same degree of heat, in varying temperatures*.
In consequence of which property, the human body preserves its tempera-
ture, of from thirty to forty degrees (Reaumur's scale) under the frozen
climate of the polar regions, as well as in the burning atmosphere of
the torrid zone. It is by the exercise of sensibility and of contrac-
tility, that is, by the exercise of the functions over which these vital
powers preside, that the body resists the equally destructive influence of
excessive heat and cold.

If we were to admit caloricity as one of the vital properties, because,
according to Professor Chaussier that power of preserving a uniform
warmth is a very remarkable phenomenon; we might be led to suppose,
a distinct cause or a peculiar property to operate iu producing other phe-
nomena of no less importance.

Barthez and Professor Dumas have fallen into the same error, the for-
mer, in wishing to establish the existence of a power of permanent siutua-
tion in the molecules of muscular fibres; the latter, in adding to sensibili-
lity and contractility a third property, which he terms the power of
vital resistance. Living muscles are torn with much more difficulty than
when dead, because the contractility which these organs possess m the
highest degree, is incessantly tending to preserve the contact of the mo-
lecules, the series of which forms the muscular fibre, and even to draw
them into closer connexion. This fact, which is brought forward as a
proof of the existence of a peculiar power, is easily explained, on the
principle of contractility.

Organized and living bodies resist putrefaction, from the very circum-
stance of their being endowed with life. The continual motion of the
fluids, the re-action of the solids on the fluids, the successive and conti-
nual renovation of the latter, by the reception of new chyle, their constant
purification by means of the secretions, through which the products ani-
malized in excess are parted with, such are the causes which prevent the
putrefactive action from taking place in bodies endowed with life, not-
withstanding the multiplicity and the volatility of their elements. Their
preservation is therefore a secondary effect, and depending on the exer-
cise of the functions regulated by sensibility and contractility. Nature
is distinguished for deriving a multitude of effects from a very small
number of causes, it therefore shows a very imperfect acquaintance with
her laws to assign a separate cause to each fact.

The separation of the chyle, which takes place in the duodenum, from
the admixture of the bile with the alimentary substance, the vivification
of the blood by respiration, the secretion of the fluids in tha conglobate
glands, nutrition in the organs, are so many acts of the living oeconomy,

* See the notes on the subject of animal heat contained in the CHAPTER ON RES-
PIRATION.

3D

to which one might feel disposed to assign distinct causes ; but these
chemico-vital processes, are so subordinate to sensibility and contractili-
ty, that they are met with only in organs endowed with these two proper-
ties, and they take place, in a degree more or less perfect, according to
the condition of these properties in the organs in which they occur.

We have stated that there exists two great modifications of sensibility
and contractility ; that sensibility is divided into percipient sensibility and
latent sensibility ^ that contractility is at times voluntary, at others involun-
tary, and that the latter may be perceivable or insensible.

" Perceiving, (cerebral, nervous, animal, sensib ility, per-
ceptibility.}
With consciousness of impressions or perceptibility ;

requires a peculiar apparatus.
SENSIBILITY. < Latent, (nutritive, organic sensibility.)

Without consciousness of impressions; or, general
sensibility, common to every thing that has life; it
has no peculiar organ, and is found universally
. diffused in living parts, animal or vegetable*.
'Voluntary and sentient, subordinate to perceptibility.

CONTRACTILITY. J Involuntary and insensible, corresponding to latent sen-
sibility. Tonicity.
^Involuntary and sentient.
The cause of this last modification of contractility, appears to depend
on the peculiar organization of the system of the great sympathetic
nerves. From these nerves, the heart, the digestive canal, Sec. seem to
receive the power of exerting sensible contraction, an effect produced by
the direct application of a stimulus, and over which volition has no con-
troul, as will be stated in speaking of those nerves.

Sensibility and contractility offer a vast number of differences, the prin-
cipal of which depend on the age, the sex, the regimen, the climate, the
state of waking or of sleep, health or of sickness, on the relative develope-
ment of the lymphatic, cellular, or adipose systems, on the proportions
which exist between the nervous and muscular systems.

In the first place, the principle of sensibility and contractility may, in
its action, be likened to a fluid flowing from any source whatsoever,
which is consumed, repaired, and drained by use, re-supplied, or exhaust-
ed, equally distributed, or, occasionally concentrated on certain organs.

Secondly. Sensibility, like contractility, is very considerable at the in-
stant of birth, and seems to diminish more or less rapidly till death.

Thirdly. The liveliness and frequency of impressions wear it out very
early. It, in a manner, repairs itself, that is, recovers its original deli-
cacy, when the sentient organs have been long at rest. Thus, an epicure,
whose taste has grown dull with high living, will recover all its accuracy,
if during several months, instead of spiced ragouts and spiritous liquors,
he lives on dry bread and plain water. In like manner, contractility be-
comes exhausted in the muscles which are too long employed, and it is
recovered during the repose of sleep.

Fourthly. The following is an instance of the manner in which sensi-
bility becomes concentrated on one organ, and appears to forsake the

See Note at p. 17.

31

others : when the venereal excitement is in its highest degree, animals
under its influence receive blows and stings without pain. Domestic
animals in that condition, are often ill treated, without appearing to feel
what is done to them. If the hind legs of the toad are cut off, at the time
that he is holding the female firmly embraced, and is pouring his prolific
seminal fluid on the ova which are issuing at her anus, he does not lose
his hold, he seems insensible to every other sensation; as a man who is
taken up with one thought, and absorbed in reflexion, is scarcely diverted
from it by any means that can be employed. When during the influence
of satyriasis, the vital power is carried to excess in the penis, patients
have been known, (as we are told by Aetius) to cut off both their testicles,
without suffering the pain usually attending so severe an operation. It
is by this law of sensibility, that we are to explain the observation of
Hippocrates, that two parts of the body cannot be in pain at the same
time. If two pains come on at once, the more violent prevents the slight-
er from being felt; Arribo partes non possunt dolore simul. Duobus dolori-
bus, simul orientibus, vehementior obseurat alterum. (Hipp.) In cases of
scrophulous swellings, the parts are observed to inflame, to become pain-
ful, and suppuration occurs but rarely in every part at once, if the case is
serious and attended with acute pain. The germ of a disease or of a
slighter affection, may sometimes remain dormant under a greater pain.
I was once overturned in a carriage, from the awkwardness of a coach-
man, the windows were broken and my wrists sprained. The right wrist
which had suffered most, swelled first ; I employed the proper treatment,
and when at the end of a wgpk, the swelling and the pain had almost com-
pletely ceased, and the right hand was beginniug to recover its suppleness
and flexibility, the left wrist swelled and in its turn became pained ; two
complaints, if they may be called such, appeared in succession, and sepa-
rately went through their regular course*.

The perfection of one sense is never obtained but at the expense of an-
other ; the blind who bestow more attention on the sensations communi-
cated by the sense of touch and of hearing, often astonish us by the deli-
cacy of these organs, so that, as has been observed, those who, to improve
the human voice, have dared to mutilate their fellow-creatures, by de-
priving them of the organs of generation, might have bethought thetn-

* John Hunter maintains from theory, the position that no two different fevers can
take place at the same time in the constitution, but that if the two causes of disease
exist together, the diseases themselves must be vicarious ; and he verifies Ms reason-
ings from experience.

On Thursday, the 16th of May, 1775, I inoculated a gentleman's child, and it was
•vedthat I made pretty large punctures. On the Sunday following, viz. the nine-
teenth, he appeared to have received the infection, a small inflammation or redness ap-
pearing round each puncture, and a small tumour. On the twentieth and twenty-first,
the child was feverish, hut I declared that it was not the variolous fever, as the inflam-
mation had not at all advanced since the nineteenth. On the twenty-second a consider-
ible eruption appeared, which was evidently the measles, and the sores on the anus
appeared to go back, becoming less inflamed.

" On the twenty-third he was very full of the measles ; but the punctures on the arms
were in the same state as on the preceding day.

" On the twenty-fifth, the measles began to disappear, on the twenty-sixth andtwen
seventh, tbe punctures began again to look a little red. On the tw*»nti7.«;«*u +K~ :_

^animation inerpas^rl. nnrl thf>rf» iiroo o i;«-*1^ , r 1 f\

in-

selves of putting; out their eyes, to render them more sensible to the
sweet impressions of harmony.

Fifthly. Duringsound sleep, the exercise of the percipient faculty, and
that of voluntary contractility, are entirely suspended. During that state,
it seems as if some covering were thrown over the sentient extremities.
We know how hard the hearing becomes, how dull the senses of smell and
of taste become, how dim the sight, a cloud spreading before the eyes,
the moment we are fallen asleep. Fir quidam. exquisitissima sensibilitate
prsedituS) semi consopitus coibat ; huic^ ut si velamento levi glans obductus
fuisse, sensus volufitatis referebatur.

Sixthly. Sensibility is more lively, and more easily excited in the in-
habitants of warm climates than in those of northern regions. What a
prodigious difference there is, in that respect, between the native of Ger-
many and of the southern provinces of France. Travellers tell us, that
there are in the neighbourhood of the poles, natives, so little endowed
with sensibility, that they feel no pain from the deepest wounds. The in-
habitants of the coast of North America, if we may believe the testimony
of Dixofi and Vancouver, thrust into the soles of their feet, sharp nails
and pieces of glass, without feeling the slightest uneasiness. On the con-
trary, the slightest prick from a thorn, for instance, in the foot, is in the
strongest African, frequently followed by convulsions and locked jaw. —
The impression of the air is alone sufficient to produce the same accident
in the negro children in the colonies, the greater number of whom die of
locked jaw, a few days after birth.

Montesquieu* very justly observed this difjpence which exists in the
sensibility of the southern and northern nations, and he says of the latter,
that " if you would tickle you must flay them."

Now, as the imagination is always proportioned to the sensibility, all
the arts that are cultivated and brought to perfection, only by the exer-
cise of that faculty, will flourish with difficulty near the icy polar regions,
unless the powerful influence 'of climate be counteracted by well directed
moral and physical causes. f

Man is of all beings, the one that most powerfully resists the influence
of external causes : and although the influence of climate is sufficient to
modify his external appearance, so as to lead to a division of the species
into several distinct varieties or kinds, this superficial impression is very

* This philosopher has borrowed from the father of physic, one of his most brilliant
and paradoxical opinions. In his conception, warm climates are the seat of despotism,
and the cold, the seat of liberty. This error is completely refuted in the profound and
philosophical work of Volney on Egypt and Syria. He shows, that what Montesquieu
has said of cold climates applies to mountainous regions, while a champaign is more
favourable to the establishment of tyranny. Hippocrates had said of the Asiatics, that
their being less warlike than the Europeans, depended on the differences of climate,
and likewise on the despotic form of their government. And he observes, that men,
who do not enjoy their natural rights, but whose affections are controuled by masters,
cannot feel the bold passion of war. See Chap. XI. on the Varieties of the Hnman
Species — Author's JVote.

fices
modo in

rante, hebes et langmdus factus, membra sua zegre trahit, ac ille, qui ut frigido aqui-
lone, cursu glaciali, se exercet, universum corpus firmus, mobilis, expeditus ! GREG-
ORY Consp.Med. Theorei — [Got/man.]

different from the great alterations to which other beings are exposed,
from the mere change of climate. Man is every where indigenous, and
exists in all climates; while the plants and animals of the equator lan-
guish and die when conveyed to the polar regions. From the flexibility
of his nature, man enjoys the power of adapting himself to the most op-
posite situations, of establishing, between them and himself, relations
compatible with the preservation of life. Nevertheless, it is not without
difficulty that man undergoes these changes, and accustoms himself to
new impressions. The periodical return of the season determines that
of certain derangements, to which the animal oeconomy is subject. The
same diseases manifest themselves under the influence of the same tem-
perature, and to use an ingenious comparison, resemble those birds of
passage which visit us ut stated seasons of the year. Thus hemorrhages
and eruptive affections come on with the return of the spring, summer
comes attended by bilious fevers, autumn brings on a return of dysen-
teric affections, and winter abounds in inflammation of the lungs and
other parts. The influence of climate on the human body, does not show
itself merely in occasioning epidemic diseases, the consideration of which
led to the establishing what physicians call medical constitutions. This in-
fluence operates on man in health, as well as in sickness; and to say
nothing of the alterations which our moral nature experiences from the
tendency of love, rendered more impetuous with the return of spring, or
of melancholy, to which nervous people are often subject towards the
end of autumn, when the trees are shedding their leaves, the increase of
growth is particularly remarkable at the time of the first growth of
plants, as was observed again and again, by a friend of mine, physician
to a large seminary.

Seventhly. Sensibility is greater in women and children ; their nerves*
are likewise larger and softer, in proportion to the other parts of the
body. In general, the principle of sensibility seems to decrease, in pro-
portion as it has contributed to the developement of the acts of life ; and
the power of being impressed by external objects, diminishes gradually
with age, so that there is a period of decrepid old age, at which death ap-
pears a necessary consequence of the complete exhaustion of that princi-
ple. In short, as I have said in describing the progress of death, at its
approach, sensibility shows increase of activity and liveliness, as if its
quantity required to be completely exhausted, before the termination of
existence, or as if the organs made a last effort to cling to life.

The developement of the cellular and adipose substance, diminishes
the energy of sensibility, the extremities of the nerves being more cover-
ed, and therefore not so immediately applied to the objects, the impres-
sions which when felt, are more obscure. The fat operates on the nerves,
as wool would do on vibrating chords, if wrapped round them, to fix
them, to prevent their quiverings, and stop their vibrations.

Very nervous women are very thin ; persons of much sensibility have
seldom much fleshiness. Swine, in which the nerves are covered by a
thick layer of fat, are the most insensible of all animals. The suscepti-
bility of the nerves may be diminished, and their sensibility blunted by
pressure. The application of a bandage firmly rolled round the body and
limbs of an hysterical woman, will diminish the violence of her fits. In

* Their voluntary nerves;

34

dressing wounds affected with what is called the hospital gangrene, i
have often relieved the pain, by desiring an assistant to apply firm pres-
sure above the sore.

Ninthly. There exists between the force of the muscles, and the sen-
sibility of the nerves; between the sensible energy and the force of contrac-
tion, a constant opposition, so that the most vigorous athletics, whose mus-
cles are capable of the most prodigious efforts, and of the most powerful
contractions, are but slightly affected by impressions, and are with
difficulty roused into action, as we have explained in giving a history of
the nervous and muscular temperaments, which are characterized by this
difference. Hence, man has more sensibility than the quadrupeds,
although his nerves are smaller than theirs, which seem destined to
set the muscles in action, and to serve as nerves of motion, rather than
of sensation.

There is no muscular fibre, however minute, in which we are not oblig-
ed to admit the existence of a small nervous filament, to which it probably
owes the power of contracting; contractility, at least voluntary contrac-
tility, does not appear to be inherent in the muscular fibre, nor independ-
ent of the nerves, through the medium of which, the will determines the
action of the muscles ; and if these last organs were insulated, contract
on the direct application of a stimulus, is there not reason to suspect, that
this stimulus acts on that portion of nerves which remains in the muscle,
after it has been insulated, and which is intimately united in its fibres ?
The animals which have no distinct nervous system, possess at once in
all their parts, sensibility and contractility ; these two properties become
blended in the organs, as well as in the phenomena of life, and can
be perceived separate, only by a pure abstraction of the mind, which
considers in succession the impression produced on these beings, and
the motion of their substance, which is an immediate consequence of
that impression.

We will not enter any further into a consideration of the laws and phe-
nomena of the vital properties, for fear of being led into useless repeti-
tions, when we come to the history of the functions over which they pre-
side. We will conclude what relates to them, by presenting the two
most important features of their history, I mean, sympathy and habit.

§VII. OF SYMPATHY.

There exist among all the parts of the living body, intimate relations;
all correspond to each other, and carry on a reciprocal intercourse of
sensations and affections. These links which unite together all the or-
gans, by establishing a wonderful concurrence, and a perfect harmony
among all the actions that take place in the animal oeconomy, are known
under the name of Sympathies. The nature of this phenomenon is yet
unknown; we know not why, when a part is irritated, another very dis-
tant part partakes in that irritation, or even contracts: we do not even
understand what are the instruments of sympathy, that is, what are the
organs which connect two parts, in such a manner, that when one feels
or acts, the other is affected. But though beyond explanation, sympathy
is not the less important in the oeconomy of living beings ; and these
connexions between remote parts, constitute one of the most remark-
able differences between those beings and inorganic bodies. No-
thing similar is observable in dead or inanimate nature, in which all

35

things are connected together, only by palpable and material links; here
the chain is invisible, the connexion evident, the cause occult, and the
effect apparent.

Whytt has clearly shown, that the nerves cannot be considered as the
exclusive instruments of sympathy*, since several muscles of a limb
which receive filaments from the same nerve, do not sympathize together,
while there may be a close and manifest relation between two
parts, of which the nerves have no immediate connexion, since each ner-
vous filament having one of its extremities terminating in the brain, the
other, in the part to which it is sent, remains distinct from those of the
same trunk, and does not communicate with them.

Sympathies may be distinguished into different kinds. In the first
place, two organs, which execute similar functions; — the kidnies may
supply each other's office. When the uterus is in a state of pregnancy,
the breasts participate inits condition, and there is determined into them
a flow of blood necessary to the secretion which is to take place.
Secondly. The continuity of membranes is a powerful source of sympa-
thy. The presence of worms in the bowels, determines an uneasy itch-
ing around the nostrils. When there is a stone in the bladder, a certain
degree of itching is felt at the extremity of the glans. The secretion
of several fluids is determined in the same manner: thus, the presence of
food in the mouth, causes at the extremity of the parotid duct, an irri-
tation which extends to the parotid glands, calls them into action, and
increases their secretion. Thirdly. If the pituitary membrane is irrita-
ted, the diaphragm with which it has no immediate organic connexion,
nervous, vascular, or membranous, contracts and occasions sneezing. Is
not this sympathy one of those which Haller ascribed to a re-action of
the sensorium commune ? If the impression produced on the olfactory
nerves by snuff, is too powerful, the uneasy sensation is transmitted to
the brain, which determines towards the diaphragm, a quantity of the
principle of motion sufficient to enable that muscle suddenly to contract
the dimensions of the chest, so as to expel a column of air, that may de-
tach from the pituitary membrane, the substances that are a cause of un-
easiness to it. Fourthly. Does not the principle of life seem to controul
at pleasure the phenomena of sympathy ? The rectum, when irritated by
the presence of the excrements, contracts ; what cause determines the ac-
cessory and simultaneous action of the diaphragm and abdominal mus-
cles ? Does this connexion depend on organic communications ? Why,
then, is not the sympathy reciprocal, and why does not the rectum con-
tract, when the diaphragm is irritated ? Fifthly. Can the repeated habit
of the same motions explain the harmony which is observed in the sym-
metrical organs ? Why, when our sight is directed to an object, placed

* Whytt's opinion must be cautiously received, for the following reason. We know
of no mode by which impressions can be communicated, except through the medium of
the nerves. It would then, be a much safer conclusion, to state that we are ignorant
of the exact manner in which sympathies are affected by the nerves, than to resort to a
supposed cause. We do not see any particular necessity that nerves going to several
muscles of a limb should cause them uniformly to sympathise. In the bi-ain we find
nerves endowed with the most dissimilar powers arising almost from the same point
and from the same cerebral substance. For a sketch of some nervous communications
and an explanation of certain sympathies, see a paper by John D. Godman^ M. D. in
the Philad. Journal of Med. and Phys. Sciences, Vol. VH, p. 237-

laterally, does the rectus externus of the eye on that side, act at the same
time as the rectus interims of the other eye? The indispensable utility
of this phenomenon, in keeping a parallelism of the axis of vision is very
obvious, but who can assign the cause? Why are rotatory motions,
in different directions, performed with so much difficulty by the arm
and leg of the same side of the body. Can it be called a just idea of
the innumerable varieties of this phenomenon, and of its frequent ano-
malies, to say, with Rega, that there are sympathies of action or of con-
tractility (consensus actionum) sympathies of sensibility (consensus passio-
num. )

All these difficulties render it pardonable in Whytt, to have consider-
ed the soul as the sole cause of sympathy? which was, in fact, a modest
avowal of the difficulty of explaining the subject. We are not justifi-
ed in considering sympathy as an anamolous action, as an aberration
of the vital power*. Can it be said, that the natural order of sensibility
and irritability is inverted, in the sympathetic erection of the clitoris and
of the nipple, or in the turgesence of the breasts, determined by the gra-
vid state of the uterus?

It is by means of sympathy that all the organs concur in the same end,
and yield each other mutual assistance. It affords us the means of ex-
plaining, how an affection, at first local or limited in its extent, spreads
and extends to all the systems ; it is thus that every morbid process is
carried on. The diseases termed general, always originate^ through the
medium of association, in the insulated affection of an organ or a system
of organs.

In fact,, the affections which appear to us most complex, in the number,
the variety, and the dissimilarity of their symptoms, consist of only one,
or of a small number of primitive or essential elements, all the rest are
accessory, and depend on numerous sympathies ot the affected organ,
with the other organs of the animal (Economy. Thus, if the stomach is
the seat of irritation, from foulness of its contents, pains of all kinds
come on, but especially in the head and limbs, with a burning heat, nau-
sea, loss of appetite, anxiety, and these symptoms constitute a disease,
which appears to affect the whole system.

To go on with the same illustration, the stomach, when oppressed by
irritating substances, contracts spontaneously to get rid of them. The
universal disturbance which their presence occasions, seems directed to-
wards the same end, as if the suffering organ called upon all the others to
assist in relieving it.

These synergies, or aggregate motions, tending to one end, and arising
out of the laws of sympathy, constitute the diseases termed general, as

* Sympathy may be considered that state v/hich an organ or texture presents, which
hokls a certain relation to the condition which characterises another orgun or texture*
in health or in disease : or it may be viewed as a certain relative state of the vital power
as it exists in separate organs or textures ; as when one part is excited another par-
ticipates in the change and evinces a similar feeling-, motion, or function.

Sympathies may be classed into the reflex and direct. The former may be chiefly
referred to the cerebral nerves and to the reaction of the sensorium, as when the
Schneiderian membrane is irritated the diaphragm is affected in consequence of the
excitement conveyed to the brain, and thence to this muscle by means of its voluntary
nerves/ The latter class takes place independently of the sensorium, and arises from
the ramification and distribution of the ganglial nerves, especially those which are sent
to the Muscular system. For the elucidation of this subject, sec APPENDIX, Note E.

us well as the greater part of those which are called local. It is by means
of them, and through these kinds of organic insurrections, if we may be
permitted to use that expression, which perfectly expresses our meaning,
that nature struggles with advantage, and rids herself of the morbific
principle, or of the cause of the disease; and the art of exciting and di-
recting these actions, furnishes the materials of the most important doc-
trines of the practice of medicine. I have used the terms excite and di-
rect; for it is necessary at times to increase, at others to diminish their
intensity and force, and on some occasions to excite them, when nature,
overwhelmed under disease, is almost incapable of re-action. This last
circumstance belongs to the diseases of the most dangerous kind, if we
include those in which the efforts of nature, though marked by a certain
degree of energy, are without connection, or consent, and frustrated by
their want of coherence. The character of these affections was first
well expressed by Selle, who substituted, for the term malignant, which
used to be applied to them without any precise meaning, that of ataxic,*
which points out very correctly, the want of order, and the irregular suc-
cession of their symptomsf.

A knowledge of symptoms is of the highest importance in the practice
of medicine!. When we wish to avert an irritation fixed in a diseased
organ, experience and observation prove, that it is on the organ which
bears to it the closest sympathetic connexions, that it is useful to apply
medicines intended to excite counter-irritation.

This might perhaps be the fittest place to inquire into the nature of
those concealed relations which draw men together, and of those aver-
sions which prevent their union ; to discover the causes of those secret
impulses which lead two beings towards each other; and force them to
yield to an irresistible propensity. We might inquire into the reason of
antipathy, and in a word, establish the complete theory of moral sen-
timents and affections. Such an undertaking is greatly above our
strength, and besides, does not absolutely belong to our. subject. It would
require a considerable time, and whoever should undertake it, would be
in considerable danger of losing his way at every step, in the extensive
field of conjectures§.

* a.r<t&t, confusion ; from a, priv. anil TAC.IS, order. — Godman.

j Symptomala ncn'osa, nee inter se, neqne causis manifestis rcspondentia. Ordo tert.
actatse, C. G. Selle. Rudimenta pyretologix methodic*.

t This information may be obtained by consulting1 the works of the ancients, and
especially of Hippocrates, who appears to have felt all the importance of this subject.
Among the moderns, Vanhelmont, Baglivi, Rega, Whytt, Hunter, Barthez, and Bichat,
have collected on this subject, a great number of facts obtained from experiments on
animals, and especially from observations on diseases. — Authors Note.

§ That law of the animal oeconomy, termed " sympathy or consent of parts," is a very
important one, and has hitherto been too much overlooked in our speculations respect-
ing- the phenomena of health and disease. There are indeed, not wanting some, who
have aflected scepticism as to the very existence of such a law — True it is, that, at pre-
sent, we have no very distinct intelligence relative to the nature of the principle ; but
are we on this account to question its existence ? With equal reason might we doubt
of the sensibility or irritability of the body. By whom has the precise nature of either
of these qualities of vital matter been demonstrated ? Yet we are persuaded of their
existence from the phenomena which they exhibit, and it is by the same description of
evidence that we ar*, or ought to be, assured of the existence of sympathy.

" Causa latct, vis est noiissima."
Of the manner in which sympathetic impressions are extended as well as of the cause

§ VII. OF HABIT.

It is easier to teel the meaning of this term than to define it. Habit,
however, may be said to consist in the frequent repetition of certain acts,
or certain motions, in which the whole body participates, or only some
of its'parts. The most remarkable effect of habit, is to weaken after a
time the sensibility of organs. Thus, a catheter introduced along the
urethra, and allowed to remain there, causes during the first day, rather
sharp pain, on the second day, it feels less uneasy ; on the third day it is
only troublesome; and on the fourth, the patient scarcely feels it. The
use of snuff at first increases the secretion of mucus in the nose, but
if continued a certain time, it ceases to affect the pituitary membrane,
and the secretion would diminish considerably but for the practice of in-
creasing daily the quantity of that acrid powder; the presence of a ca-
nula in thenasalduct, after the operation for fistula lachrymalis, increases
at first the mucous secretion of that canal ; but in proportion as it
becomes accustomed to the extraneous body, the secretion returns to its
natural condition.

It is only by our sensations that we are aware of our existence. Life,
to make use of the figurative language of system, of a modern writer,
consists in the action of stimuli on the vital powers. (Tola vita, quanta
est, consistit in stimulo, et vi vitali. Brown.) Sentient beings feel a conti-

ofthe more intimate consent which exists between parts, we are not accurately in-
formed. Those sympathies which prevail among the various viscera of the abdomen,
and between them and the head, neck and contents of the thorax, may, perhaps,
be explained by the extensive anastomoses of the intercostals with almost all the
nerves which proceed from the spinal marrow. But there are many other sympa-
thies, equally conspicuous, between parts, the nerves of which (apparently)* have
not the slightest connexion. Here it appears that, either by the co-operation of
different organs in the performance of a function, as in the complex apparatus sub-
servient to respiration, or from similarity of structure, parts, though detached, be-
ing prone to be affected by the same cause, as the parotid glands and testes in the
7nale, and the same gland with the mammae in the female, the habit of acting in unison
is acquired, and sometimes confirmed. This habit of concerted action is called associ-
ation, and has been adopted as a principle by Locke, by Hartley, and by Darwin, to ac-
count for the connexion which is discernable in many of the motions of the body, as well
as in the operations of the mind. Both the sound and morbid states of the system pre-
sent numerous instances of these associated actions, some of which are constant and
uniform, while others are occasional, and anamolous, produced as it were accident-
ally.

The principle of sympathy extends throughout the body, every portion of it being
susceptible of associative actions, by which means the different parts are linked toge-
ther so as to form one whole. — Certain organs however, are more eminently endowed
with the property, as the uterus, the brain, and especially the stomach. This last vis-
cus constitutes the chief medium of sympathetic connexion. With it, the brain, thtf
organs of sense, and deglutition, the whole of the thoracic and abdominal viscera;
the parts of generation in each sex, the blood vessels, the joints, the exterior surface,
and in short all the parts of the system however minute, maintain a close and intimate
sympathy. Placed in the middle, the stomach is the centre of the greatest sphere of
sympathy. But, besides this great sphere, there are many subordinate ones, which our

narrow limits will not permit us particularly to designate : as for example, the uterus,
with the different portions of its own system, the ovaries, the mammae, &c. &c. It was

on account of its vast dominio "x **-*'—<* — — -*^~- *»•-«• v—

Helmont selected the stomac
Stahl and Mcholte — Chapmai

on account of its vast dominion over the system, by its multiplied sympathies, that Van
Helmont selected the stomach as the residence of his archxuz, the anima medica} of

39

nual necessity of renewed emotions : all their actions tend to the obtain-
ing agreeable or disagreeable sensations; for in the absence of other sen-
sations, pain is sometimes attended \vith enjoyment. Those who have
exhausted every kind of enjoyment, and who have had no pleasures un-
gratified, are led to suicide from a weariness of life; who can live, when
all power of feeling is gone?

The following is the most extraordinary and remarkable instance
known, of the manner in which habit and a frequent repetition of the
same impressions, wear out by degrees the sensibility of organs. A shep-
herd, about the age of fifteen, became addicted to onanism, and to such a
degree, as to practise it seven or eight times in a day. Emission became
at last so difficult, that he would strive for an hour, and then discharge
only a few drops of blood. At the age of six and twenty his hand became
insufficient, all he could do, was to keep the penis in a continual state of
priapism. He then bethought himself of tickling the internal part of
his urethra, by means of a bit of wood six inches long, and he would
spend in that occupation several hours, while tending his flock in the
solitude of the mountains. By a continuation of this titillation for six-
teen years, the canal of the urethra became hard, callous, and insensible.
The piece of wood then became as ineffectual as his hand; at last, after
much fruitless effort, he one day, in despair, drew from his pocket a
blunt knife, and made an incision into his glans, along the course of the
urethra; this operation, which would have been painful to any ojK^else;
was in him attended with a sensation of pleasure, followed by a copious
emission. He had recourse to his new discovery, every time his desires
returned. When after an incision into the cavernous bodies the
blood flowed profusely, he stopped the hemorrhage, by applying around
the penis a pretty tight ligature. At last, after repeating the same pro-
cess, perhaps a thousand times, he ended in splitting his penis into two
equal parts, from the meatus urinarius to the scrotum, very near to the
symphysis pubis. When he had got so far, unable to carry his incision
any farther, and again reduced to new privations, he had recourse to a
piece of wood, shorter than the former : he introduced it into what re-
mained of the urethra, and exciting at pleasure the extremities of the
ejaculatory ducts, he provoked easily the discharge o^Semen. He con-
tinued this about ten years, after that long space of time, he one day in-
troduced his bit of wood so carelessly, that it slipped from his fingers and
dropped into the bladder. Excruciating pain and serious symptoms
came on. The patient was conveyed to the Hospital at Narbonne. The
surgeon, surprised at the sight of two penes of ordinary size, both capa-
ble of erection, and in that stage diverging on both sides, and seeing be-
sides from the scars and from the callous edges of the division, that this
conformation was not congenital, obliged the patient to give him an ac-
count of his life, which he did, with the details which have been related.
This wretch was cut as for the stone, recovered of the operation, but
died three months after, of an abcess in the right side of the chest, his
phthisical state having been evidently brought on by the practice of
onanism carried on nearly forty years*.

The habit of suffering, renders us in the end insensible to pain; but
every thing in this world is balanced, and if habit lightens our evils, by

* Chopart, maladies des voies urinaires. Tome II.

40

blunting sensibility, it on the other baud drains th source of our sweetest
enjoyments. Pleasure and pain, these two extremes of sensation, in a
manner, approximate to each other, and become indifferent to him who
is accustomed to them*. Hence arises inconstancy, or rather that insa-
tiable desire of varying the objects of our inclinations, that imperious
want of new emotions; hence we possess with indifference what was pur-
sued with the utmost ardour and perseverance, and even cease to be im-
pressed by those charms which once held us captivated.

A striking instance of the powerful influence of habit on the action of
organs, is afforded by that criminal, who, we are told by Sanctorius, was
taken ill on being removed from a noisome dungeon, and did not (recover
till he was placed in the impure air to which he had been long accus-
tomed. Mithridates, that formidable rival of the Roman power, dread-
ing to be taken alive by his enemies, tried in vain to put an end to his
life, by taking large doses of the most subtle poisons, because he had
long inured himself to their actionf. It has, therefore, been justly said
of habit, that it is a second nature, whose laws ought to be respected.

The organs of generation in women, in consequence of their lively
sensibility, are in an especial manner submitted to the powerful influence
of habit. The womb, after a miscarriage, has a tendency to a renewal of
the same occurrence, when the same period of pregnancy recurs, so that
the greatest precautions ure necessary to prevent abortion in women,
who are subject to it, when they have reached the month in which they
before miscarried.

May not death be considered as a natural consequence of the laws of
sensibility ? Life, depending on the continual excitement of the living
solids by the fluids which moisten them, ceases, because the parts endow-
ed with sensibility and contractility, after long habitude of the impres-
sions of those fluids, lose their capacity of feeling them. Their action
gradually extinguished, would perhaps revive, if the energy of the sti-
mulating power were increased.

A knowledge of the power of habit, is a useful guide in the application
of remedies, the greatest part of which operate in the cure of diseases,,
only by modifying sensibility. A wound in which lint has kept up the
degree of inflammation necessary to cicatrization, becomes insensible to
that application, the parts become spungy and soft, and the cure is pro-
tracted. The lint should then be covered with an irritating powder, and
the pledgits soaked in an active fluid : one may safely increase the doses
of a medicine which has been long employed. Thus, in the treatment
of the venereal disease by mercurials, the dose is to be gradually in-
creased ; xvith the same view, Frederic Hoffman recommended in the
treatment of chronic diseases, that the remedies should be suspended for

* This is so beautifully expressed by Dr. Gregory, that we cannot resist the tempta-
tion to introduce his words: — [Godman.]

tf Voluptas et dolor (ut pulchra Socratis fabula docet) sorores fuerunt, utcunque dis-
similes, diversamque sortem experts ; altera ninrirum optata et grata omnibus, altera
pariter invisa ; quas tamen J upiter ita sociavit et tarn indissolubili vinculo conjunxit,
tit quamvis natura contrarias et diverse spectantes, quicunque alterutram complectitur,
alteram trahat simul."

•j- In some very rare cases, habit produces a quit contrary effect. Cullen states, that
he knew persons so accustomed to excite vomiting1 in themselves, that the twentieth
part of a grain of tartar emetic was sufficient to exhe a convulsive action of the sto--
roach.-— Aiithor's Note.

41

-a time and then resumed, lest the system should get accustomed to
them, and their influence be lost. The same motive should lead one to
vary the treatment, and to employ, in succession, those medicines to
which nearly the same qualities are assigned, for, each of them call forth
the sensibility in a peculiar manner. The nervous system may be com-
pared to an earth abounding in various juices, and for a full display of
whose fecundity, it is necessary that the husbandman commit to it the
germs of various plants.

It is very remarkable that habit, or the frequent repetition of the same
act, which uniformly, under all circumstances, and in all organs, blunts
physical sensibility, should improve the intellect, and increase the faci-
lity, and activity of execution of all the operations of the understanding,
or of the actions which depend on them. " Habit impairs the sensitive
power, and improves the judgment" Bichat was therefore incorrect, when
in his distinction of the organs which are subservient to the functions
of assimilation, from those which serve to keep up our relation with
the surrounding objects: he maintained, that the sensibility of the latter
becomes more exquisite, while the sensibility of the former becomes im-
paired from habit.

But can a painter, because he judges more correctly than the ignorant,
of the beauties of a picture, be said to see it better? Surely not, for, he
may with a sight far less penetrating, and more infirm, form a more ac-
curate analysis, from the habit which he has acquired, and judge with a
great deal more promptitude and certainty, of the several parts of the
whole ; just as the practised ear of the musician seizes, in a piece of mu-
sic, and during the most rapid execution, the expression and the value of
all the notes and tones. The error has arisen, from its being forgotten,
that, correctly speaking, it is not the eyes that see, or the ears that hear:
that the impressions produced by the sounds on these organs, are but the
occasional cause of the sensation, or of the perception of which the brain
is the exclusive seat. Which has the more delicate sense of hearing,
the North American savage, who hears the noise of the step of his ene-
mies, at distances that astonish us, or the artist who does not hear a
person speaking at the distance of fifty paces from him, but who directs
with judgment, all the operations of a great orchestra, and who distin-
guishes skilfully, the effect of each part ?

Bring down to a frugal Pythagorean regimen, one of our modem epi-
cures : his palate, exhausted of its sensibility by the most savoury dishes,
by ardent liquors, and the most exquisite ragouts, will discover no taste
in dry bread. Let him, however, live on bread, if he can, for some time,
it will soon appear to him to have a grateful taste, as it does to those who
make it their principal article of food, or who take it only with substan-
ces which have not a very distinct taste. Although with the sense of
smell, that of taste furnishes us only with ideas the most directly con-
nected with our preservation, those which most turn upon the wants of
our animal nature : although we retain, with difficulty, the impressions of
these senses, and that, to enable us to retain them, they must be often re-
peated ; the epicure has so carefully analyzed them, that he has attained
to the discernment of the faintest differences of taste, all those delicacies
of sensation, which, as Montesquieu says, are lost to us vulgar eaters.

The motions, under the direction of the will, acquire by the precision
of the determinations, the same aptness, facility, and readiness, and
the dancer, who surprises us with his agility, hag reflected, more than

F

42

might be imagined, on the very complicated steps of which a ballet r*
composed.

Morbid sensibility, is equally under the influence of habit. I have al-
ways observed, that discharges from the urethra become less painful from
their frequency. There is nothing down to disease itself, that is uotmade
lighter by habit, as has been well observed by Hippocrates.

It remains then demonstrated, even as a general thesis, that habit, or
the frequent repetition of the same acts, while it regularly reduces physi-
cal sensibility, improves intelligence, and gives facility and promptness to
all the motions that are under the direction of the will.

§IX. OF THE VITAL PRINCIPLE*.

The words -vital principle, vital force, See. do not express a being exist-
ing by itself, and independent of the actions by which it is manifested:
it must be used only as an abridged formula, which serves to mark the
total of the powers that animate living bodies, and distinguish them
from inert matter. So that, whenever, in the course of this section, I
shall use these terms, or any equivalent, it is to be taken as if I had said,
the aggregate of the properties and laws that regulate the animal cecono-
my. This explanation is become indispensable, now that several wri-
ters, realizing a mere abstraction, have spoken of the vital principle,
as of something very distinct from the body, as of a being altpgether se-
parable, which they have invested with feeling, and thought, and even
deliberate intentions.

From the remotest antiquity, the many and striking differences of liv-
ing, and inorganic bodies, have led some philosophers to conceive in the
former, a principle of particular actions, a force which maintains the har-
mony of their functions, and directs them all to a common end, the pre-
servation of individuals and of the species. This simple and luminous
doctrine, has remained, even to our own days, only modified in its pas-
sage through many years : and, no one now disputes the existence of a
principle of life, which subjects the beings, that enjoy it, to a system of
laws different from those which inanimate beings obey ; a force which
might be characterized, as withdrawing the bodies it animates, from the
absolute dominion of chemical affinities, which would else, from the
multiplicity of their elements, oct on them with great power ; and as
maintaining them in a nearly equal temperature, whatever may be that
of the atmosphere. Its essence is not in preserving the aggregation of
constituent molecules, but in drawing to it other molecules, which, by
assimilation to the organs it pervades, replace those that are carried off
in daily waste, and serve for their nourishment and growth.

All the phenomena that are to be observed in the living human body,
might be brought as proofs of the principle which animates it. — The
actions of the digestive organs on its food ; the absorption, by the chy-
lous vessels, of its nutritious parts; the circulation of these nutritious
juices through the sanguineous system ; the changes they undergo in
their passage throughnhe lungs, and the secretary glands; the impressi-
bility by outward objects ; the power of approaching or avoiding them;
in a word, all the functions that are carried on throughout the animal

See APPENDIX, Note A.

43

oeconomy, proclaim its existence. But it is customary to take a proof of
it yet more direct, from the properties with which the organs of these
functions are endowed. We have examined these properties, and we
have seen that each of them presents us with, at least, two great modifi-
cations; that the last discovers three, which are, voluntary contractility,
contractility involuntary and insensible, Stahl's tonic motion ; and
lastly, contractility involuntary and sensible, as that of the heart and
the intestines.

If it is useful to analyse, in order to know, it is of equal importance not
to multiply causes, from misconceiving the nature of effects; and, if,
on the one hand, the multitude of the phenomena of life, inclines us to
the belief of many causes to produce them; the unfailing harmony that
pervades all the actions, their mutual connexions, and reciprocal depen-
dencies, point much more decisively to a sole agent, as causing, direct-
ing, and controuling these phenomena.

The hypothesis of the vital principle, is to the philosophy of living
beings, what attraction is to astronomy. To calculate the revolutions of
the planets, this science is compelled to recognize a force, which draws
them constantly towards the sun, and constrains their tendency to fly
from it, within the measured distance of those ellipses, which they de-
scribe around that common centre of light and heat, which dispenses to
them, as they roll, the precious germs of life and of fertility. We are
about to speak of this force, to which all the powers that animate each
separate organ, join themselves, and in which all the vital powers are
blended, but under the declaration, for the second time, of using the term
only in a metaphorical sense. Without this precaution, I might lead you
into all the false reasonings, which those have fallen into, who have as-
signed to it a real and separate existence.

The vital power is in perpetual strife with the powers that govern in-
animate bodies. The laws of individual nature are, according to the say-
ing of antiquity, for ever struggling against those of universal nature ;
and life, which is only this contest prolonged, in favour, altogether, of
the vital powers, during health, but with uncertain issue in disease, is at
an end, the moment in which the bodies endowed with it, fall again into
the system of lifeless being. This constant opposition of vital to physi-
cal laws, both mechanical and chemical, does not withdraw, altogether,
living bodies from the controul of these laws. There are effects always
going on in the living being, chemical, physical, and mechanical: only
these effects are constantly influenced, modified, and altered by the pow-
ers of life*.

Why, when we stand up, are not all the humours carried down to the
lower parts, by the force of gravitation ? The vital power resists the com-
pletion of this hydrostatic phenomenon, and neutralizes this tendency of
the fluids, the more successfully as the individual is more robust and
vigorous. If it is one enfeebled by previous disease, the propensity will
be but imperfectly repressed: the feet, after a certain rime, swell; and
this oedematous swelling can be ascribed only to the insufficient energy
of the vital powers, which determine the distribution of the fluids, &c.

* In proof of this may be adduced the observation long- since made by Dr. AIEXAJT-
DER, that the range of temperature most favourable to the putrefaction of dead animal
matter, being between 86Q and 100P of Fahrenheit, includes the usual standard of hu-
man heat

44

When a tumbler throws himself backwards, the blood does not flow
altogether to his head, though this is become the lowest part; yet the
natural tendency of fluids downwards is not altogether overcome; it is
only diminished; for if he preserve long the same attitude, the struggle
of the hydraulic and vital powers becomes unequal: the former prevail;
they accumulate the blood upon the brain ; and the man dies.

The following experiment proves incontestibly, what has just been said
of the power of resistance, which, in the human body, more or less, effec-
tually counterbalances the force of physical laws. I applied bags filled
with very hot sand, along the leg and foot of a man whose artery had
been tied by two ligatures, in the hollow of the ham, for popliteal aneu-
rism. Not only the limb was not chilled, which is what happens when
the course of the blood is intercepted, but the extremity thus covered,
acquired a heat much above the ordinary temperature of the body. The
same apparatus applied to the sound leg, did not produce this excess of
heat, certainly, because the fulness of life, in that limb, resisted the
physical action.

The vital principle seems to act with the greater energy, as the sphere
of its activity is narrowed; which has led Pliny to say, that it was
chiefly in the smallest things that Nature has shown the fulness of
her power*.

The circulation is quicker, the pulse more frequent, the determina-
tions more prompt, in men of short stature. Such was the great Alex-
ander!; never did man of colossal make display great activity of imagi-
nation : none of them have glowed with the fire of genius. Slow in their
actions, moderate in their desires, they obey without murmuring the will
that governs them, and seem made for slavery. Agrippa (says Omilius
Probus, in his History of Augustns) advised that they should disband
the Spanish guard, and that in its room, Caesar should choose one of
German, " wotting well, that in these large bodies, there was little of
" coverte malice, and yet lesse of subtiltie, and that it was a people more
" minded to be ruled than to rule."

To judge soundly of the remarkable difference which inequality of sta-
ture brings into the character, compare extremes; set against a Colos-
sus, a little man of diminutive stature; granting, nevertheless, to this
last, full and vigorous health. You may guess that he is talkative, stir-
ring, always in action, always changing his place ; one would say that he
is labouring to recover in time, what he has lost in space. The probable
reason of this difference in the vital activity, following the difference of
stature, arises from the relative bulk of the primary organs of life. The
heart, the viscera of digestion, &c. are of nearly the same bulk in all
men : in all, the great cavities are nearly of the same extent, and it is
principally in the length of the lower limbs that the difference of stature
will be found to lie. It is easily conceivable, that the viscera supplying
the same quantity of nutritious juices to a smaller bulk, that the heart
giving the same impulse to blood which is to traverse a shorter course,
all the functions will be executed with greater rapidity and energy.

By an obvious consequence, the diseases of little men have a more
acute character; they are more vehement, and tend more rapidly to their

* Nusquam magis qiiam in minimis est Ma JVatwa. Hist. Nat. lib. II. cap. 2.

f Such was the Greater NAPOLEON ; still the subsequent assertions are too gene-
ral. We have not forgotten the size of Dr. JOHKSOJT, and mankind will never forget,
how he " glowed with the lire of genius." — '

' genius. " — Gocbnan .

45

crisis*. They have in them something of the velocity, I wtfuld even say
the instability of morbid re-action during infancy. There is nothing
even to the duration of life, on which the differences of stature have not
some influence. With this suspicion, and some curiosity to ascertain
its justness, I hare made inquiries in the hospitals, when people in ad-
vanced life are taken in, and I found them, for the most part, occupied by
old men above the middle size; so that reasoning and observation concur
in showing that all things else being equal, those of superior stature have
a grounded hope of prolonging their life beyond the ordinary term.

I have observed with many others, that the whole body unfailingly re-
ceives an increase of vigour, from the amputation of a limb. Frequently,
after the loss of a part of the body, you will see a manifest change take
place in the temperament ; those that were weak, even before the disease
which brings on the necessity of the operation, becoming robust: affec-
tions, chronic from debility, such as scrophula, tabes mesenterica, dissi-
pated $ glandular swellings resolved; which indicates a very remarkable
increase in the actions of all the organsf.

The parts most remote from the centre of circulation are, in general,
less alive than those which are nearer. Wounds of the legs and feet, are
more liable to ulcerate, because, besides the circulation of the fluids,
which the slightest weakness greatly retards in them, their life is too fee-
ble for their wounds to go quickly through their periods, and readily
cicatrize. The toes freeze first, when we remain too long exposed to
severe cold ; it is in them too that the mortification begins, which some-
times attacks a limb after the ligature of its vessels.

Thus, although we may say, that the principle of life is not seated in
any part of our being, that it animates every system of organs, every se-
parate organ, every living molecule, that it endows them with different
properties, and assigns to them, in some sort specific characters, it must
be confessed, thai there are in the living body some parts more alive,
from which all the other? seem to derive motion and life. We have al-
ready seen that these central organs, these foci of vitality, in whose life
that of the whole body is involved, diminish gradually in number in the
animal kinds, as they are more removed from man, whilst the fewer they
are, the more they are spread out over the body; so that life is more ge-
nerally diffused, and its phenomena less rigorously and strictly connect-
ed, as we descend in the scale of being, from the red and warm-blooded,
to the red and cold-blooded animals, from these to the mollusca, the
Crustacea, worms and insects, to the polypus, who forms the extreme
link of the animal chain, and lastly, to plants, of which not a few, like

* The acute diseases of tropical countries, especially fever, prove more fatal to short
men, or those of middle size, than to the tall,

•j- The extraordinary development of an organ never takes place but at the expense
of those about it, of which it draws off the juices. Aristotle observes, that the lower
extremities are most always diy, and wasted in those who are of ardent temperament,
or in habits of frequent venery. Hippocrates relates in his work (De sere, locis, et aguis,
Foe's : fol. 293.) that the Scythian women seared their right breast, that the arm on
that side might grow in size and strength. Galen speaks of Athletes, who, in his time,
kept the sexual organs in the most entire inaction, that withered, shrunk, and perished,
in some sort, by this absolute repose, they might not draw off the nutritious juices
from the sole nourishment of the muscular organs. A young man, who several times
carried off the prize by runinng at the public fetes, abstained from venery for some
months, before entering1 the lists, in perfect certainty of victorv. after this privation. —
Author'? Mte.

46

the zoophytes, so similar to them in many respects, are endowed with
the remarkable property of reproduction by slips; which implies, that
each part contains the aggregate of organs necessary to life, and can
exist alone.

The vital principle has by some been confounded with the rational soul;
but others have distinguished it from that emanation of divinity, to which,
as much as to the perfection of his organization, man owes his superiori-
ty to all the animal kinds. What bond unites the material principle,
which receives impressions and transmits them, to the intelligence which
feels, perceives, examines, compares, judges, and reasons on them?
Were man one, says Hippocrates, did his material principle make up his
whole nature, pleasure and pain would be as nothing to him : he would
be without sensation : for, how could he account to himself for impres-
sions ? Si unus- esset homo, non doleret, quiet non sciret unde doleret. Here
we stand on the confines of physiology and metaphysics; let us beware
of setting foot in the dim paths that are before us : the torch of ob-
servation would yield but ineffectual light, too faint to dispel the thick
darkness that lies over them.

The vital power is merely the vis medicatrix naturse, more powerful
than the physician, in the cure of many diseases ; the art of the physician
consisting, in most cases, in awakening or directing the action of that
power. When a thorn is thrust into a part endowed with sensibility, a
sharp pain is felt, the fluids rush in abundance to the part, it becomes
red and swollen; all the vital powers are excited, the sensibility becomes
more acute, the contractility greater, and the temperature rises. Does
not this increase of vital energy in the injured part, this process which
takes place, around the substance that is the cause of the disorder ; those
means which are provided to expel it, indicate the existence of a preserv-
ing principle, incessantly watching over the harmony of the functions,
and struggling against all the powers that may tend to interrupt its ex-
ercise, or to annihilate the vital motion?

Ttieory of inflammation*. Inflammation may, I believe, be defined; the
increase of vital properties in the part which it affects^. Sensibility becomes
more acute in the part so affected, its contractility greater; and from
that increase of sensibility and action, arise all the symptoms character-
istic of inflammation. Thus the pain, the swelling, the redness, the heat,
and the difference in the state of the secretions, denote in the part a more
energetic and active vitality.

Those who have objected to the definition which I have given of in-
flammation, have evidently mistaken the functions of the organs for their
properties. It is very true, that inflammation of the eye is attended with
loss of sight, but that circumstance depends on the opacity of the trans-
parent parts which should transmit the luminous rays to the retina. The
sight is prevented by a mechanical obstacle, but the sensibility of the

* See APPENDIX, Note G.

t IUFLAMMATIOX is a state of disease. A wound or other injury is inflicted, the nerves
ana vessels are injured, and sensibility becomes greater, because the ability to resist, or
the tone of the part is lessened. Hence slighter impressions in this condition produce
pain. The swelling is owing to the quantity of blood received into the vessels being
greater than in health, because the vessels being -weakened are distended : the redness is
produced by the quantity of blood. The heat is accumulated, because the natural pro-
cess, removing its excess by perspiration is suspended, as the previous injury and
consequences check this secretion. — Gotlman.

47

organ is augmented to such a degree, that the faintest light reaching the
bottom of the eye, through the transparent cornea dimmed by the con-
gestion of the vessels, causes in it intolerable pain. On this principle,
darkness is universally recommended to patients affected with ophthal-
mia. In like manner, when a muscle is inflamed, the action of the fibre,
its shortening, is prevented by the congestion in the cellular membrane,
which covers it and fills its interstices. The cause preventing contrac-
tion, or the exercise of contractility, is mechanical, and maybe compared
to that, which, in an inflamed lung, opposes the admission of air, and
the passage of the blood, from the right to the. left side of the heart.
Can any one call in question the increase of vital action in peripneumony ?
I am therefore of opinion, that the above definition is better than that
proposed by Bichat, in his u Anatomic Generale," a work of later date
than the first edition of these elements of physiology, and in which he
makes inflammation to consist in the increase of those vital properties
which he terms insensible.

All the parts of the human body, with the exception of ths epidermis
and its different productions, as the nails and the hair, appear capable of
inflammation. One might include among these " epidermoid" parts,
certain dry and slender tendons, as those of the flexors of the fingers,
which, when pricked, lacerated and irritated in a thousand ways, are in-
sensible to pain, and remain uninjured in the midst of a whitlow, though
attended with suppuration of all the neighbouring soft parts; and when
exposed to the air, they exfoliate instead of granulating. Organization is
so indistinct in all these parts, life so feeble and languid, that they remain
insensible to the impression of all those causes which might tend to in-
crease its activity.

The degree of sensibility in a part, the number and size of the nerves
and vessels which are sent into it, determine the degree of its aptitude to
inflammation : thus the bones and cartilages inflame with considerable
difficulty. When one of these parts is laid bare, the first effect of the
irritation to which it is exjA*t,tci, is a softening of its substance. When
a bone is laid bare, it bpcor*i?«s ^"'Jlag'rGus uid softens, in con:-;, uacnce
of the abt>oi^ticr, of the phosphate of lime which fills up the interstices of
its tissue; and it is only after this kind of incarnation, that fleshy granu-
lations begin to sprout, as may be observed on the extremities ot bones
after amputation. The difficulty w.ith which inflammation is set up in
the harder parts of the body, explains why, before the twelfth or fifteenth
day after a fracture, it is of little consequence to wards union of the bone,
that the fractured ends should be placed in opposition : not that it is right
to wait so long, before applying the proper bandages, which are indis-
pensable from the first, to prevent the pain and laceration occasioned by
the displaced bone. The blood is determined, from all quarters, towards
the irritated and painful part, which swells and assumes a red colour,
from the presence of that fluid.

The swelling would be unlimited, if, at the same time that the arteries
increase in power and calibre, to occasion that determination, the veins
and lymphatics did not acquire a corresponding energy, to enable them
to relieve the part, of the fluids which have accumulated in it, and
which irritation is constantly determining to it. The power of irrita-
bility and contractility increases with sensibility; the circulation is more
rapid in the inflamed part ; the pulsations of the capillary vessels are ma-

48

nifest. The part is likewise hotter, because, in a given time, there passes
through its tissue more arterial blood, from which a larger quantity of
caloric is disengaged, and the continued effects of the pulmonary respira-
tion are better marked in it than in any other organ.

It forms no part of our intention to treat of the varieties of inflamma-
tion : they depend principally on the structure of the organ which is
affected, on the violence and rapidity of the symptoms, and on its
effects.

Is not the turgescence of an inflamed part occasioned in the same man-
ner, as in parts subject to erection, as the corpora cavernosa of the penis
and of the clitoris, the nipples, the iris, 8cc. ? In erection of the penis, as
in inflammation, there is an irritation, a determination of fluids to the
part, an increase of sensibility and contractility; yet its condition is not
that of inflammation. Nature has so disposed the organization of these
parts, that they can sustain, without injury, those instantaneous augmen-
tations of vital energy, necessasy to the exercise of the functions per-
formed by the organs to which they belong. As in inflammation, these
congestions disappear, when the cause of irritation has ceased to act;
thus, the pupil dilates, because the iris recedes, when the eye is no longer
exposed to the rays of a vivid light. The penis returns to its naturally
flaccid and soft state, when no irritation operates to determine to it the
fluids, whose presence, as loug as the erection lasts, is easily explained
by the continuance of the irritation, without its being necessary to have
recourse to mechanical explanations, to account for that phenomenon.
When the irritation, which produces the vital turgescence of the penis
or iris, is tarried too far, or continues too long, the natural congestion
becomes morbid. It is well known, that priapism is frequently attended
•with mortification of the penis, and that the too long continued action of
light on the eye, brings on inflammation of that organ.

The preceding observations on inflammation show, that an acquaint-
ance with its phenomena is useful, even in a physiological point of view.
The vital processes, which in some organs take place in so obscure a
manner that they are imperceptible, acquire in inflammation a character
of rapidity and intensity, which renders it much easier to observe and
recognize them. Considered in a general and abstract point of view,
and merely with a reference to its object, inflammation may be consider-
ed as a means employed by nature, to repel the influence of noxious
agents, which, when introduced within the body, or on its surface, she
has no power of resisting, but by a more active developement of the pow-
ers which animate it.

During the severe winter of 1793, the chemist Pelletier repeated the
cekferated experiment of freezing mercury, and obtained a solid ball in
the%alb of a barometer, which he had for along while kept immersed in
the midst of a quantity of ice, continually moistened with nitric acid.
When the metal had attained a completely solid state, he drew the ball
from the bulb, and placed it on his hand. The heat of the parr, joined to
that of the atmosphere, soon restored the quicksilver to its fluid state : at
the same instant, he experienced in his hand so intolerable a degree of
cold, that he was obliged to drop the quicksilver instantly. There soon
came on, in the painful and chilled part, a phlegmonous inflammation,
which was cured by resolution. Quicksilver, in a solid state, is one of
the coldest bodies in nature: how very rapidly the caloric must have

49

been carried off in this case, and how deep the impression must have been
in the palm of the hand, doubly affected by the cold, and by the vital re-
action, which terminated in inflammation ! I have produced a similar ef-
fect, by endeavouring to melt a piece of ice in my hand, during the heat
of summer. In this experiment, the impression of cold is soon succeed-
ed by a sensation of acute pain and extraordinary thr.obbings, in the hand
and fore arm. When the two hands are afterwards compared, that
which held the piece of ice is extremely red, from the congestion of
blood in the cutaneous capillary tissue, and is very different in its appear-
ance, from that which was not the subject of experiment.

Analogous facts, if seriously considered, should induce the followers of
Brown to apply to the effects of cold, the distinction which he applied to
debility, of direct and indirect They would have no difficulty in ascer-
taining, that in its medical application, that negative state of caloric,
which is directly debilitating, may, nevertheless, by the re-action which
it excites, be considered as an indirect tonic.

§ X. OF THE SYSTEM OF THE GREAT SYMPATHETIC

NERVES*.

The great sympathetic nerves are to be considered as the bond destin-
ed to unite the organs of the nutritive functions, by whose action man
grows, is evolved, and incessantly repairs the continual waste attending
the vital motions. They form a nervous system, very distinct from the
system of the cerebral nerves; and, as the latter are the instruments of
the functions by which we hold intercourse with external objects, the
great sympathetic nerves supply motion and life to the organs of the in-
ward, assimilating, or nutritive functions.

In animals, without vertebrae, may not the nervous system, which floats
in the great cavities with the viscera which they contain, be considered
as consisting entirely of the great sympathetics ? t These nsrves are
principally distributed to the organs of inward life, whose activity, in
those animals, seems to grow, in proportion as their external senses, and
their faculty of locomotion, are imperfect. If the great sympathies exist
in all the animals which have a distinct nervous system, do they not, in

* See APPENDIX, Note H.

•j- TREVIRANUS, in his Biologie, considers the knotted cord found in the abdomen of
insects and worms to be the vertebral ganglia of the sympathetic nerve. That it can-
not be considered a spinal cord is evident : its situation sufficiently shows the difference.
The mollusca, and many animals removed a little above this class in the scale of crea-
tion, possess merely single ganglia, from which proceed fibrillae to the different organs.
The great sympathetic nerve is " the most general and the most original of all the
nerves." Its characters, are, however, modified in different classes. " In worms and
insects there are merely vertebral ganglia, without the coeliac ganglia of mammalia and
birds : in the acephalous mollusca there are the latter, without the former ; in the cut-
tle-fish and snails there are single ganglia of both kinds. " All these animals have no
spinal marrow ; fishes and reptiles have one, and also vertebral ganglia, but the cceliac
is not fully developed in them. (See the Observations of SERRES and WEBEE) as in birds
and mammalia.

These remarks convey the sum of the observations made by those who have inquired
into the subject. How, therefore, can the ganglial class of nerves be considered to a*
rise from the cerebral and vertebral masses ?— Copland.

G

50

an especial manner, contain the principle of vegetable life, essential to
the existence of every organized body possessing the power of diges-
tion, absorption, circulation, secretion, and nutrition ? Finally, is it
not probable, that in man, the system of the great sympathetic nerves,
has a great share in occasioning a number of diseases, and that the im-
pressions with which patients are affected, arc referred to their nu-
merous ganglions, while the brain is exclusively the seat of intellect and
thought* ?

These suggestions will, doubtless, be answered in the affirmative, if
one considers the origin, the distribution, and the peculiar structure of
these nerves, the acute sensibility of their branches, as well as the disor-
ders attending their injury.

Extended along the vertebral column, from the base of the skull to the
lower part of the sacrum, these great nerves, in some measure parasitic,
do not arise from the branches supplied them by the fifth and sixth pairs
arising from each side of the brain; they live and are nourished, as it
were, at the expense of all the nerves of the spinal marrow, from which
they receive branches, so that there is not one of them, from which one
can say, that the~*great sympathetics arise exclusively. The numerous
ganglions which are distributed along their course, divide them into so
many small systems, from which arise the nerves of the organs nearest to
them. Amidst these bulgings, considered by several physiologists, as so
many little brains, in which is performed the elaboration of the fluid
which they transmit to the nerves, no one is of more importance than the
semi-lunar ganglion, situate behind the organs which occupy the epigas-
tric region, and from which those nerves originate, which are distribu-
ted to the greater part of the viscera of the abdomen It is to the
region occupied by that ganglion, in which the great, sympathetic nerves
unite, and which may be considered as the centre of the system formed
by their union, that we refer all our agreeable sensations; there it is
that we feel in sadness, a constriction which is commonly referred to
the heart. Thence, in the sad emotions of the soul, seem to originate
those painful irradiations which trouble and disorder the exercise of all
the functions f.

The numerous filaments of the great sympathetic nerves are finer, they
are not of the same whitish colour, nor of the same consistence as the
filaments of the cerebral nerves. On that account, they are less easily
dissected^, the nervous fibrillae are less distinct, their reddish chords are

* These opinions on the uses of the great sympathetic nerves, are explained in my
Essay on the connexion of life with the circulation. This essay was published before
any thing1 that has appeared on the same subject. — Consult the .*' Memoires de la So-
cie"te Medicale pour 1'an VII." — Jl-uthor's Note.

f Consult on the subject of the epigastric centre, Van Helmont, who calls it the
archeus ; Buftbn, Bordeu, Barthez, and Lacaze, who give it the name of the phrenic
centre, because they ascribe to the diaphragm what belongs to the nervous ganglions
placed in front of its crura. — Author's Note.

t One of the best modes of dissecting them is to macerate the part, in which we wish
to trace their ramifications, during two or three days in water ; then place it for a short
time in a very dilute acid, or warm spirits, or in oil of turpentine. The filaments of
these nerves may be then traced more distinctly. Other processes, which are more
complex, are requisite to the dissection of the minuter ramifications, especially those
which supply the blood-vessels. — Copland.

Anatomists are perfectly well aware, that none of these processes are to be relied

51

moister, and they appear formed of a more homogeneous substance ;
their membranous coverings are less considerable. They are likewise
endowed with a more acute and more delicate sensibility. Every one
knows the danger attending wounds of the mesentery, a membranous du-
plicature, in itself insensible, but containing such numerous nerves des-
tined to the intestinal tube, that the most pointed instrument can scarcely
wound the mesentery, without injuring some of their branches. The
pain attending affections of the great sympathetic nerves, is of a peculiar
kind; it leads directly to the extinction of the vital power. It is a well
known fact, that a bruise of the testicles overpowers, in a moment, the
strongest man. Every one knows that patients who die of a strangulated
hernia, of volvulus, or of every other affection of the same kind, die in the
most distressing anguish, their heart feels oppressed, and they are tor-
mented with constant vomiting. Intestinal and nephritic colics are at-
tended with the same sort of pain; that attending injection of the tunica
vaginalis in hydrocele, is of the same kind. We expect a favoura-
ble event of the operation, only in those cases in which the patient has
felt pain along the spermatic chord, in the course of the spermatic nerves,
which arise, as it is well known, from the renal plexus. In the case of
wounds of the abdomen, I was led, by the nature of the pain which the
patients suffered, to prognosticate that the wounds had penetrated; the
event justified my prognostic. In all these affections of the great sympa-
thetic nerves, the pulse is frequent and hard, the face is covered with a
cold sweat, the features are sunk ; all the symptoms are alarming, and
soon terminate fatally.

The use of the system of the great sympathetic nerves is, not merely
to establish a closer connexion and a greater union between all the or-
gans which perform the functions of assimilation, but likewise to free
those parts from the influence of the will. A power of the mind so fickle
and so varying, that life would be in constant danger, if we had it in our
power to stop or suspend the exercise of functions with which life is es-,
sentially connected.

If we consider what are the organs to which the functions of assimila-
tion are entrusted, and which receive their nervous influence from the
great sympathetic nerves, we shall find that the action of the greater
number is wholly independent of the controul of the will*. The heart,
the stomach, the intestinal canal, Sec. do not obey the will, and seem to
possess a more insulated and more independent existence, and act and
rest, without any influence on our part. Some of these organs, as the
bladder, the rectum, and the muscles of respiration, which do not receive

upon ; and they also know, that a vast number of nervous filaments exhibited in en-
gravings, were never seen elsewhere. When nervous filaments are traced until they
become as small as a hair, they cannot be distinguished from cellular substance — when
coagulating agents are used, the material produces corresponding effects on all the ad-
joining textures, hence the difficulty is increased rather than diminished.— Godman.

* All these parts which receive their nerves from ganglions, are equally independent.
Professor Chaussier thinks that the upper filaments of the great sympathetic nerves
ascend along the internal carotid, and join the sphenopalatine and lenticular ganglions.
M, Ribes thinks he has ascertained by dissection, that several very long and slender
filaments follow the course of the branches of the internal carotid, and like them are
sent to the base of the brain, beyond which they cannot be traced. I have myself ob-
served, in dissection, these filaments around the branches of the internal carotid artery,
but I had always considered them to be formed of cellular substance.— Author's Note.

their nerves exclusively from the great sympathetics, are obedient to the
will, and receive from the brain the principle of motion, the former, from
the branches which the sacral nerves send to the hypogastric plexuses :
the diaphragm, from the nerves which it receives from the fifth and sixth
cervical pairs.

The great sympathetic nerves supply the diaphragm, the rectum, and
bladder, only with nerves of sensation. This provision was a very ne-
cessary one, for, if, as is the case with the heart, and the intestines, these
parts had received their nerves of motion from the great sympathetics,
their action would have been independent of the will, as is the case with
all the parts which these nerves supply with motion. The bladder and
rectum, placed at the extremities of the digestive apparatus, and destin-
ed to serve as reservoirs to the excrementitious residue of our solid and
liquid aliments, would have been constantly evacuating their contents, as
fast as the substances which are destined to be retained within them for
some time, reached their cavity.

On the other hand, if the diaphragm had received its nerves of motion
from the great sympathetics, respiration would have ceased to be a vo-
luntary function, of which we might at pleasure accelerate, slacken, or
even completely suspend the action. To prove that the act of respira-
tion is under the controul of the will, we may have recourse to analogy,
and adduce the instance of reptiles, as lizards, frogs, serpents, salaman-
ders, and toads, which are cold-blooded animals, and in which this func-
tion is manifestly voluntary. We may further mention those slaves, who,
we are told by Galen, put themselves to death, when summoned before
their executioners or judges. According to thtet physiologist, and others,
they choked themselves by swallowing their tongue. But it is sufficient
to know how the muscles that bind down the tongue are situated, and the
degree of motion which they allow, to see how little ground there is for
that opinion. The action of the brain would, in that case, have been no
lotiger necessary to the maintenance of life ; in an animal without a brain,
respiration would have continued, and the circulation would not have
been interrupted. The death of that viscus would not have been attend-
ed with the sudden death of all the rest.

The nerves which arise from the spinal marrow, and which give to the
diaphragm the power of contraction, a power which that muscle loses
suddenly, if these nerves be tied, appear to me the chief links which
unite the internal assimilating or nutritive functions, to those which
keep up the relation of the animal with external objects. Without this
bond of union, the series of vital phenomena would have been less close,
and their dependence less necessary. Had it not been for the necessity
that the diaphragm should receive from the brain, by means of the phre-
nic nerves, the principle which determines its contractions, acephalous
animals, which are born without that organ, might continue to live as
they did before birth, when the organs of nutritive life received blood,
which had undergone, in the lungs of the mother, the changes necessary
to life. But where the bond which united them to the mother is destroy-
ed, obliged themselves to produce in their fluids, the necessary changes,
by the inhalation of the vivifying principle contained in the atmosphere,
they no longer can obey that necessity; the organs of respiration are de-
ficient in the principle which should excite them.

53

When an internal inflammation is of small extent*, and is seated in a
part in which there are not many nerves, and whose tissue yields easily to
the humours which irritation determines into it, the whole morbid action
takes place in the affected part, and the general order of the functions is
not sensibly deranged. But when inflammation takes place in a part en-
dowed with much sensibility, or of a close texture, as the fingers and toes,
then fever comes on, because a sympathy in the morbid action takes place,
between the diseased part and the rest of the system. The diffusion of
the local action almost infalliby takes place, when inflammation occurs in
one of the organs of the assimilating functions. This effect may be con-
sidered as uniform, though Morgagni mentions several instances of in-
flammation of the liver, marked by no peculiar symptoms.

A knowledge of the great sympathetic nerves accounts for this differ-
ence. When an external part is affected with inflammation, the irritation
which it suffers, is by means of its nerves propagated to the brain, which
by a re-actionf; called by Vicq-d'Azyr (who on this subject has only de-
veloped the opinions of Vanhelmont) internal nervous action, transmits
that irritation to the heart, to the organs of respiration, of digestion, and
of secretion, in which the phenomena, denoting a febrile state, are prin-
cipally evolved. When, on tiie contrary, the heart, the lungs, or any
other internal organ is affected with acute inflammation, all the viscera
partake in the derangement with which any one of them is affected, and
without the intervention of the brain. They are all intimately connected
by the filaments which they receive from the great sympathetic nerves?
and, by means of that. nervous system, which is in an especial manner ap-
propriated to them, they carry on a more intimate intercourse of sensa-
tions and affections. Besides, the derangement of the important functions
entrusted to the diseased organs, is necessarily attended with appropriate
changes in all the acts of the animal csconomy, in the same manner, no
doubt, as the defect of one wheel interrupts or disturbs the mechanism of
the whole machine:}:.

* A thousand pustules in the small-pox occasion only a moderate degree of fever, if
they are at a distance from each other ; but if the disease is confluent, that is, if the
pustules are close together, and run into each other, the fever becomes considerable, and
the patient's life endangered. The fleshy granulations which sprout in abundance from
an ulcerated surface, are so many small phlegmons unaccompanied by a febrile state,
but if brought close to each other by irritation, that condition will not fail to ensue.
Vaccination is not, in the greater number of cases, attended by the slightest febrile ac-
tion, if, as I always have done, the punctures are made at a certain distance from each
other, so that the inflammatory areolse may not run into each other. — luthor's Note.

| The cerebral re-action appears to be in no measure necessary to the induction of
symptomatic fever : it may, however, contribute to its continuance. The irritation ap-
pears to be propagated to the heart in consequence of the numerous connexions which
this organ holds, by means of the ganglial nerves,, with the other viscera ; and owing to
the continuous reticulation of these nerves upon the blood-vessels from the heart to the
capillary terminations. — Copland.

$ The late experiments, performed on the nervous system by that excellent anatomist
and physiologist, Charles Bell, have kd to some very interesting conclusions, and have
thrown much light on a very obscure subject. He arranges the nerves in the following
manner. There are a number of nerves arising from the spinal marrow by double roots,
which pass out laterally to the regular divisions of the body, never taking a course longi-
tudinally. These nerves are common to all animals from the worm up to man, and are
for the common purposes of sensation and volition. These are termed regular nei*vea;
each having two roots, one from the anterior and the other from the posterior division
of the medulla spinalis. The 5th pair ; suboccipital ; seven cervical ; twelve dorsal ;
five lumbar and six sacral constitute thirty-two (kuble, perfect, orregular nerves. The

54

There exists in the stomach an union of the cerebral and sympathetic
nerves, which explains the manifest dependency, in which that one of the
three supports of life is found with the brain; a dependency so marked,
that every strong affection of the soul, every violent agitation of the mind,
weakens or even totally suspends the action of digestion in the stomach.
This combination of cerebral and sympathetic nerves likewise accounts
for a phenomenon, which was mentioned in speaking of the influence of
habit on the action of the organs. The stomach differs essentially from
the intestinal canal j for, far from getting accustomed to the impression
of emetics, so as to become by degrees less sensible to their action, as the
intestines to the action of purgatives, though three grains of tartar emetic
could, at first, scarcely excite it, half a grain only of that salt is able to
bring on vomiting, when by frequent use, it has acquired the habit of the
motions excited by its action. It is riot in that case with the stomach, as
with a limb, whose muscles perform motions with the greater ease and
facility, when they have been often practised.

§ XI. OF THE RELATIONS OF PHYSIOLOGY TO SEVERAL
OTHER SCIENCES.

It would be entertaining a very incorrect notion of the science of liv-
ing man, to imagine with some authors, that it solely consists in the ap-
plication of the laws of Natural Philosophy, to the explanation of the
phenomena of the animal ceconomy. Physiology is an independent sci-
ence; resting upon truths of its own, which it draws from the observa-
tion of those actions, which, in their aggregate succession and connexion,
constitute life. It is enriched, it is true, with facts furnished to it by
Natural Philosophy, Chemistry, and Mathematics ; but what it has bor-
rowed from these, is accessory merely, and does not form an essential part
of the edifice of the science. Thus, the better to understand the mechan-
ism of hearing and vision, physiology borrows from acoustics and optics,
elementary notions on sound and light; and, in order to obtain a more
correct knowledge of the nature of our solids and fluids, and of the
manner in which animal substances are constantly passing from the one
to the other of these two conditions, physiology calls in the aid of che-
mistry. Thus, geometry and mechanism furnish it with the means of
better understanding the advantageous form of the organs, and the per-
fection of their structure*.

remaining nerves are called irregular. They have a single fasciculus or root, from
one column of the spinal marrow. They derive their name from the irregularity
of their ramifications, and their want of symmetry ; are superadded to the original class
and correspond to the number and complication of the superadded organs. The 3d,
4th and 6th, going to the eye ; the 7th (portio duru) to the face ; the 9th to the tongue ;
the glossopharyngeal to the pharynx ; the vagus to the larynx, lungs, heart and sto-
mach ; the phrenic to the diaphragm ; the spinal accessory to the muscles of the shoul-
der ; and the external respiratory to the outside of the chest, are the irregular or super-
added nerves. (See Transactions of the Royal Society for 1821 ; British Journal of Sci-
ence, Jan. 1822 ; the first number of Magendie's Journal of Physiology ; and the Phila-
delphia Journal of Med. and Pliysl. Science for August, 1893, p. 240.)— Godroan.

* A knowledge of mathematics, and of the whole circle of natural philosophy, in-
cluding more especially chemistry and natural history, and, in a more particular manner,
human and comparative anatomy, is requisite to the successful study of physiology.
This branch of knowledge, although independent of some of these, is yet more easily
acquired, and its difficulties are better explained, by a previous acquaintance with all of

35

No study carries along v?ith it a more lively interest, than that of the
admirable relations existing between the conformation of our parts and
the external objects, to which they are applied. These relations are cal-
culated with such precision, and laid down with such accuracy, that the
organs of sense and of motion, considered in this point of view, may be
regarded as the model of the most ingenious productions of art. So true
it is in the words of the great physician of Pergamus, that nature did
every thing before art, and better*.

At the beginning of the last century, geometrical physicians, deceived
by an appearance of rigid precision, attempted to explain every thing by
the calibre of vessels, their length, their curvatures, the compound ratio
of the action of solids and the impulse of fluids. Hence were formed theo-
ries so very imperfect, that, as we shall see, in treating of several points
of physiology, and especially of the force with which the heart acts, not
one of those who proposed them, coincides with those who have since
followed their track. However, it does not admit of a doubt, that there
occur in the animal machine, effects which are referable to the laws of
hydraulics. The brain, for example, required a large and constant sup-
ply of arterial blood, vivified by recent circulation through the lungs; but
the too rapid and abrupt access of that fluid in the brain, might have dis-
ordered its structure. Nature, therefore, has, as we shall mention in the
article of the cerebral circulation, employed all the hydraulic resources
in her power, to break the force Avith which the blood enters the brain,
and to slacken its course.

Has man ever applied the laws of hydraulics in a more felicitous man-
ner than nature, in the rete mirable formed at the base of the brain by the
carotids of quadrupeds? An arrangement truly remarkable, without which,
the blood conveyed to the brain by those arteries, impelled by a force su-
perior to that of th*^ human heart, and not having to overome the resist-
ance of its own gravity, would infallibly have occasioned a disorganiza-
tion of that organ, whose consistence is so soft.

As to the application which is allowable of mathematical sciences, it
maybe said, that, as in physiology, but little is absolutely certainf, and
much merely probable, we can reckon only on probabilities, and seek our
elements in facts deduced from observation or experience ; facts which
when collected and multiplied to a certain degree, lead to results of equal
value with truths absolutely demonstrated.

The phenomena presented by living bodies vary incessantly, in their
activity, their intensity, and their velocity. How can mathematical for-
mulae apply to such variable elements? As well might you inclose in a
frail vessel, hermetically sealed, a fluid subject to expansion, and of vari-
able bulk. The motions of progression in man and in the animals, afford,

them. Pathology and the treatment of diseases, also, reflect a light upon physiology
uhich they first derived from this productive source.

* Quandoquidem natura, nt arbitror, et prior tempore sit, et in operibus magis sapiens
qumnars. GALENUS, de usu partiwn, lib. VII. cap. 13.

It was from observing the manner in which nature prevents the diffusion of light in
the globe of the eye, that Euler was led to the improvement of his astronomical teles-
cope luthor's Note.

j This is to be understood, as applying only to the causes of the phenomena, and not
to the phenomena themselves; for physiology is perhaps richer than any other science,
in facts unquestionable, and easily ascertained by observation. — Auih'ir\ -Vote.

56

nevertheless, sufficient correct applications of calculation. Calculation
may likewise be applied with advantage, to the measurement of the re-
sults of our different secretions to ascertain the quantity of air, or of ali-
ment, introduced into our organs, Sec.

Among; the principal causes which have retarded, in a considerable de<
gree, the progress of physiology, may be enumerated the mistake of those
who have endeavoured to explain all the phenomena of living bodies, by
a single science, as chemistry, hydraulics, Sec. while the union of all these
sciences, will not account for the sum of these phenomena. The abuse,
however, of these sciences, should not be a reason for setting them aside
altogether. The facts obtained from natural philosophy, chemistry, me-
chanics, and geometry, are so many means applicable to the solution of
the great problem of the vital ceconomy; a solution which, though as yet
undiscovered, should not be considered as unattainable, and to which we
shall approach the nearer, as we attempt it with a greater number of da-
ta. But it cannot be too often repeated, that he alone can hope for that
honour, who, in the application of the laws of natural philosophy to liv-
ing bodies, will take into account the powers inherent in organized na-
ture, wnich controul, with supreme influence, all the acts of life, and mo-
dify the results that appear most to depend on the laws by which inor-
ganic bodies are governed.

Anatomy and physiology are united by such close relations, that it has
been an opinion with some, that they are absolutely inseparable. If phy-
siology, say they, has for its object, a knowledge of the functions carried
on by our organs, how is one to understand their mechanism, without
knowing the instruments by which they are performed? One might as
well attempt to explain the manner in which the hand of a watch performs
the circle of its diurnal revolution, without understanding the springs
and numerous wheels which set it in motion. Haller is the first who es-
tablished the connexion between anatomy and physiology, and who illus-
trated it in his great work. Since Haller, a great number of anatomists,
and among them Soemmering*, in a work recently published, have com-
bined, as much as possible, these two sciences ; the latter, in treating se-
parately of each system of organs, explains what is best known of their
uses and properties.

However close the connexion between anatomy and physiology, they
have, nevertheless, appeared perfectly distinct to the greater number of
authors, and we have several valuable works on anatomy, of which phy-
siology occupies but a small part. — This manner of embracing the two
sciences appears to me attended with the greatest advantage; in fact, if
the insulated description of organs suffices to the physiologist who wishes
to study their functions, that method is attended with the disadvantage of
furnishing few truly useful views, in the practice of operative surgery.
To render the knowledge of the human body more especially applicable
to the practice of surgery, it is necessary, not only to consider separately
the different parts, but likewise to view them in their connexion, and to
determine precisely their relations. The anatomist, who knows that the
principal artery of the thigh is the crural, — that, continued under the

* J. Ch. Soemmering, de carports humani fabrica, 6 vols. 8vo. 1S04.

This work possesses a great deal of merit ; independent of its anatomical correctness,,
the author has throughout adhered to the best rules of logic, and analyses the human
structure with great clearness and force. — Godman.

57

name of popliteal, it passes behind the knee in its way to the leg*—
that, in its course, it supplies with branches different parts of the limb —
even though he knew perfectly the name, the number of these branches,
the varieties to which they are subject, the parts to which they are dis-
tributed, would nevertheless possess a knowledge of that branch of the
system, almost useless in the treatment of the diseases with which it may
be affected. The situation of the artery, its direction, the parts which
surround it, its precise relations to each of them, its superficial or deep
seated course, &c. are the only circumstances from which he can derive
auy advantage.

He who, in this point of view, cultivates anatomy, may be compared to
the chemist; in the same manner as the latter is never better acquainted
with a substance, than when he is able to decompose it, and to reproduce
it from a combination of its parts, so the anatomist is well acquainted
with the body of man, only, when having studied separately, and with the
greatest care, each of his organs and each of the systems, formed by the
collection of a certain number of similar organs, he is able to assign to
each of them its place, to determine its relations, and the proportions
which it bears in the structure of anyone of our limbs. The study of the lat-
ter is much more difficult and extensive than that of the former; for, the
chemist who decomposes and recompounds a well-known substance,
phosphate of lime, for instance, attains only to the knowledge of its con-
stituent principles, and respective proportions? the phenomena of situa-
tion altogether escape him. The anatomist, on the other hand, who knows
rtiat such apart is composed of bones, of muscles, of nerves, of vessels,
must know, not only every one of these parts, their relative bulk, but the
exact place in which they are to be found.

Anatomy, pursued in this spirit, offers a field of wide extent : it is the
art which Leibnitz called the analysis of situation, analysis situs ; and the
knowledge of it is too important not to require a separate place among
the departments of medical knowledge. I will not pass over the motives
that are alleged for combining anatomy and physiology in one course of
instruction. Anatomy, confined to the mere description of the organs, is
too dry and fatiguing ; physiology throws over it interest and variety;
it helps to ensure the attention of the hearers, who will retain more per-
manently, what they have listened to with pleasure. Would not one think
that physiological details were, for an audience, what is contrived for a
sick and froward child, in the honey that is rubbed on the edge of the cup,
to disguise the bitterness of the draught that is to recall him to life ? In
combining two objects, of which one has no interest but that of useful-
ness, whilst the other is engaging as well, the attention will be not merely
divided, but altogether distracted, and the mind of those who read or lis-
ten, will skim over dry details, to seize with avidity what furnishes more
to its activity of intelligence. Anatomy is to physiology what geography
is to history. General considerations on the situation, the size, the form,
the relations, the structure of the organ, are an indispensable preparation
to the perfect understanding of its functions : accordingly, you shall find
much anatomy in physiological treatises, as you find much geographical
detail in faithful historians.

I have said enough, I trust, to escape the reproach of not having filled
my book with anatomical descriptions, from the multitude of excellent
works we possess on the anatomy of the human body. Let us now inquire
what relation physiology bears to Comparative Anatomy.

H

58

If a machine can be perfectly known, only alter taking it to pieces?
down to its simplest elements ; if the mechanism of the whole action is
conceived, only by separately studying the action of each different part,
Comparative Anatomy, by aid of which we can study, in the great chain
which the animal kinds compose, the separate action of each organ, ap-
preciate its absolute or relative importance, consider it, at first, insulated
and reduced, so to speak, to its own powers, in order to determine what
part it bears in the carrying on of a function ; Comparative Anatomy
is of absolute necessity to him who would make great progress in the
knowledge of man ; it may be looked upon as a sort of analytic me-
thod, by means of which we more completely attain to the knowledge of
ourselves.

In order to conceive rightly the operations of the human intellect, and
explain the generation of the faculties of the soul, metaphysicians have
imagined a statue, into which they have infused a gradual animation, by
investing it, one by one, with our organs of sensation. Now, Nature has
realized in some sort this dream of philosophy. There are animals to
which she has entirely denied the organs of sight and hearing; in some,
taste and smell seem to have no separate existence from touch 5 in others,
she has exercised a sort of analysis on a system of parts which all concur
in one function. It is thus, that in some animals, divesting the organ of
hearing of the accessories allotted to collect, transmit, and modify the
rays of sound, she has reduced it to a simple cavity, filled with a gelati-
nous fluid, in which float the extremities of the acoustic nerve, alone fit-
ted to reeeive the impression of sound ; a fact which overthrows all the
hypotheses that had ascribed this sensation to other parts of the auditory
apparatus.

Of all the physical sciences, Comparative Anatomy is that which fur-
nishes the most useful facts to physiology. Like physiology, it is concerned
with organized living beings : there is, therefore, no need of watching
against the false applications, so often made from the sciences, whose ob-
jects are matter inorganic and dead, or which study, in living beings only
the general properties of matter. Haller was so well aware of the utility
of introducing this science into physiology, that he has brought together
the greater part of the facts known in his time, on the anatomy of ani-
mals, at the head of each chapter of his immortal work.

This general consideration of living and animated beings, so well adapt-
ed to unveiling the secret of our organization, has this further advantage,
that it enlarges the sphere of ideas of him who applies to it. Let him who
aspires to that largeness of conception, so requisite in medicine, where
facts are so multiplied and various, explanations so contradictory, and
rules of conduct so unfixed, cast a general glance on this great division
of organized beings, of which many, in their physical structure, so nearly
resemble man : — he will see the sovereign Architect of the world distri-
buting to all, the element of life and activity, giving to some a less pow-
er of motion, to others more j so that, formed all on one model, they
seem only the infinitely varied, but gradual shades of the same form, if
forms have shades like colours; never passing abruptly from one to ano-
ther, but rising or falling by gentle and due degrees; covering the inter-
val that separates two different beings, with many species that serve as
a transition* from one to the other, and which present a continuous series

* The conception is noble and interesting of a scale of being1, which, as was said by
C, Bonnet, connecting all the worlds, embracing all the spheres, should extend from

59

of advancement or degradation ; organization being constantly simplified,
In descending from man to the inferior creatures ; but rising In complex-
ity, in re ascending from those animals to man, who is the most complex
being in nature, and was justly considered, by ancient philosophy, as the
master-piece of the Creator.

If the intimate structure of our organs totally eludes our investigation,
it is, that the finest and most delicate of their constituent parts are of such
minute dimensions, that our senses have no hold on them. It is then
well to have recourse to analogy, and to study the organization of ani-
mals that exhibit the same organs on a larger scale. Thus, the cellular
texture of the lungs, which cannot be distinctly shown in man, on account
of the extreme minuteness of the smallest bronchise, may be satisfactorily
seen in the vesicular lungs of salamanders and frogs. In like manner, the
scales which cover the bodies of fishes and reptiles, or the legs of
birds, give us a just idea of the structure of the epidermis, and of the
arrangement of its small scales, which lie over each other, in a part of
their surface.

The human structure being more complicated, must produce effects
more numerous, and results more varied, and more difficult to under-
stand. In commencing the study of the animal organization by that of
man, we do not therefore, follow the analytic method, we do not proceed
from what is simple, to what is more complex. It would perhaps be an
easier and a more natural way of arriving at a solution of the grand and
difficult problem of the animal oeconomy, to begin by explaining its most
simple terms; to rise by degrees from plants to vegetating animals, as
polypi; from these to white-blooded animals, then to fishes and reptiles;
from the latter to warm-blooded animals, and lastly, to man himself,
placed at the head of that long series of beings whose existence becomes
complicated, in proportion as they approach him.

The study of every part of natural history, and especially of Compara-
tive Anatomy, cannot fail, therefore, to prove of infinite advantage to the
physiologist; a truth well expressed by the eloquent M. de Buffon*, who
says, that if there existed no animals, the nature of man would be still
more incomprehensible.

I shall say nothing of the well-known relations of physiology to medical
science, of which it is justly considered as the base or support. Medi-
cine, called by some the art of healing, by others more properly, the art
of treating diseases, may be defined the art of preserving health of curing

the atom to the most exalted of cherubim. Without carrying it so high or so low, if
\ve confine it to the natural beings with which we are well acquainted, and which can
be brought under observation, it will be seen, that the idea is not so chimerical as some
writers of most respectable authority have supposed it. The plan traced by C. Bonet is
evidently defective ; we find in it beings set beside each otlrer, that have but faint lines
of resemblance, or altogether illusive. The present state of the natural sciences would
allow of its being better done : one might try at least for all bodies what Jussieu has
executed with regard to vegetable productions ; and if this undertaking, in the hands of
men the most able to bring it to a successful termination, left any thing defective, would
not that imperfection be an indication of the existence of other worlds, or of lands yet
unknown on the globe ws inha*bit ; undiscovered regions where those animals, and
plants and minerals would be fo%nd which were wanting to fill up the gaps in the im-
mense series of co- ordinate existence. Demonstratum fuit et hoc, nullam rent contraries,
vel omnino multum differentes, quaUtates recipere posse, nisi per media prius iter fecerit.—
GALENUS de usu partium, lib iv. cap. 12. — Author's Note.

* Histoire Nat torn. V. 12mo. p. 241. Discours sur la nature des anitnaux.

60

diseases, or of rendering them more supportable; medicine, in ail its
parts, is enlightened by physiology, and cannot have a surer guide. Ow-
ing to a neglect of this auspicious guide, therapeutics and materia medica
long remained involved in a mist of conjectures and hypotheses. Physi-
cians should never for a moment forget, that as'a great number* of dis-
eases consist in a derangement oi the vital function, all their efforts
should tend to bring back sensibility and contractility to their natural con-
dition : that the best classification of diseases and of medicines, is that
which is founded on a judicious distinction of the vital powers. With
this view it is that M. Alibert, in his elements of materia medica, classes
medicines according to their effects on sensibility or contractility, and
according to the organs on which their action is particularly exerted.

§ XII. CLASSIFICATION OF THE VITAL FUNCTIONS.

After having treated separately of the vital powers or faculties, nothing
is easier than to arrange, in a clear and methodical order, the functions
carried on by the organs which these powers call into action. The term
function^ might be defined, means of existence. This definition would be the
more just as life is only the exercise of these functions, and as in cases,
when any one of the more important can no longer be carried on. From
not distinguishing the faculties from the functions which are merely the
acts of faculties or powers, several modern divisions, though far prefera-
ble to the old classification of the functions into vital, animal, and natural,
are, nevertheless, deficient in accuracy and simplicity. Thus Vicq-d'Azyr,
in the classification of the phenomena of physiology inserted in the dis-
course which he has prefixed to his work on anatomy, mistakes the
cause for the effect, and places sensibility and irritability among the
functions, and commits another mistake, by ranking among the latter, os-
sification, which is but apeculiar mode of nutrition, belonging to parts of
a hard structure.

The best method of classing the actions which are performed in
the living human body is doubtless, that by which they are distributed
and arranged according to the object which they fulfil. Aristotle, Buf-
fon, and especially Grimaud, have laid on that base the foundation of a
method which we shall adopt, with the modifications which we are about
to mention.

Aristotle and Buffon had observed, that among the acts of the living
oeconomy, some were common to all beings that have life, to plants and
animals during sleep and in waking, while others seemed to belong ex-
clusively to man, and to the animals which more or less resemble him.
Of these two modes of existence, the one vegetative, the other animal,
the former appeared to them the more essential, as being more diffused,

* All diseases consist in physical derangements, as solutions of continuity, displace-
ments, organic alterations, as polypi, aneurisms, and other affections resulting from or-
ganic affection and alteration of structure ; vital lesions, as fevers, ataxite, adynamise,
vesanise, &c. see Nosographie Chirnrgicale. — Jluthor's^'ote.

f The function of any part, is the office or duty it fulfills, or the end for which it is
designed. The function of the lachrymal gland is to secrete tears: — of the ducts, to
convey them to the nose, &c. Life must exist anterior to the performance of function,
although the correct discharge of the latter is necessary to the continuance of the former.
The definition, as applied to the term function, is incorrect—when it refers to the re-
sults produced by function, it is unexceptionable. — Godman.

61

and consisting merely in assimilation of nutritive molecules, in the nutri-
tion absolutely necessary to the preservation of the living being*, who, as
his substance is incessantly wasting-, would soon cease to exist, if these
continual losses were not always repaired by the act of nutrition.

Grimaud, Professor of Physiology at Montpellier, too soon lost to the
science which he cultivated as a philosopher, truly deserving that name,
adopted this simple and luminous division, developed it better than had
been done before him, and uniformly followed in his lectures and in his
worksf. This division of the functions into internal, which he likewise
calls digestive, and into external or loco-motive, lately brought forward
under the name of organic and animal, the former of which terms is quite
inaccurate and defective, since it leads to a belief, that the animal life, or
of relation is not confined to organs, and that their vital instruments are
solely employed on internal life or of nutrition (Motus assimilationis, Bacon ;
Bias alterativum, VanhelmoLt.) This distinction does not comprehend
the whole of the phenomena, and does not embrace the sum of the func-
tions which are performed in the animal ceconomy. In fact, there are
not found in the two great classes which it establishes, the acts by which
animals and vegetables reproduce and perpetuate themselves, and immor-
talize the duration of their species. All the functions destined to the pre-
servation of the species are not included 5 they merely relate to the func-
tions subservient to the preservation of individuals.

I have, therefore, thought it right to include under two general classes,
in the first place, the functions which belong to the preservation of the
species, functions without which man might exist, as we see in eunuchs,
but without which the human species would soon perish, from a loss
of the power of reproduction. In laying down these two great divi-
sions, I have merely considered the object and end which each function
has to fulfil.

Among the functions which are employed in the preservation of the
individual, some fulfil this office by assimilating to his own Substance
the food with which he is nourished ; the others, by establishing, in
a manner suited to his existence, his relations with the beings which sur-
round him.

The functions destined to the preservation of the species, may likewise
be divided into two classes. Those of the first class require the concourse
of two sexes; they constitute generation, properly so called; those of the
second order, exclusively belong to the female, who, after conception, is

* Namanima nutritiva etiam aliis inest, etprima et maxima, commums facuUas animse,
secundum quam omnibus vivere inest AIUSTOT. de anim, lib. ii. cap. 4.

| Ir> his MS. lectures on physiology, he seems to feel a complacency in that division
which he had in a manner appropriated to himself, by his happy illustrations of it, and
by the changes which he had introduced into it. In every lecture, I might almost say
in every page, he returns to this division, explains it, dilates, and comments upon it.
« The functions," says he, " may be divided into two great classes ; some are formed in
the interior of the body, and exclusively belong1 to it ; others take place outwardly, and
belong to external objects," &c. The digestive power presides, in his opinion, over
the internal fw-ctions,\\hose object is nutrition: the loco-motive power directs the ex-
ternal functions. " ft is by means of the organs of sense that the animal enlarges
his existence, that he applies and distributes it on the surrounding objects, that he takes
cognizance of the qualities in those objects which concern him ; it is by means of the
muscles essentially obedient to the organs of sense, that lie adapts himself to those ob-
jects, that he places himself in a manner suited to the mode of tbeir activity," &c. —
Jluthor's Note.

alone destined to bear, to nourish, to bring into the world, and suckle the
new being, the result of conception*.

The internal, assimilating, or nutritive functions concur in the same
end, and all serve to the elaboration of the nutritive matter. The aliment
once admitted into the body, is subjected to the action of the digestive or-
gans, which separate its nutritive parts ; the absorbents take it up, and
convey it into the mass of fluids; the circulatory system conveys it to all
the parts of the body, makes it flow towards the organs; the lungs and
the secretory glands supply it with certain elements, and deprive it of
others, alter, modify, and animalize it; in fine, nutrition, which may be
considered as the complement of assimilating functions, whose object it
is to provide for the maintenance and growth of the organs, applies to
them this animalized substance, assimilated by successive acts, when it has
become quite similar to them.

Several, however, of these functions, serve at once to preserve and to
destroy. Absorption, which takes up extraneous molecules to be em-
ployed in the growth of the organs, takes up equally the organic mole-
cules which are detached by motion, friction, heat, and all the other phy-
sical, chemical, and vital causes. The action of the heart and of the
blood-vessels sends these fragments, together with the parts truly recre-
mentitious, towards the lungs, which, at the same time that they bring
about a combination of the nutritive parts with the oxygen of the atmos-
phere, separate from the blood the materials which can no longer be em-
ployed in nourishing the organs; the same power sends them towards the
secretory glands, which not only purify what is liquid, by separating from
it that which cannot without danger remain in the animal ceconomy, but
which likewise elaborate or prepare peculiar fluids, some of which are
results of the act of nutrition, are employed in that act, and impart to the
substances on which it is performed a certain degree of animalization,
(as to the bile and saliva) while the others seem to be intermediate states,
which the nutritive, particles of the food are obliged to undergo, before
the complete animalization 5 such are the serous fluids and the fat.

It might perhaps seem more in conformity to the order of nature, to
have combined the account of respiration with that of the circulation by
treating of the course of the venous blood, after the action of the absorb-
ent vessels, with which the veins have so much analogy. — Then to have
treated of the phenomena of respiration, or of the conversion of the ve-
nous blood into arterial, and of the course of the latter into all the parts
of the body, by the action of the heart and arteries; but, the advantage
which would be obtained from a method so contrary to the common prac-
tice, which is to consider separately the functions of circulation and res-
piration, appeared to me too unimportant to justify its adoption.

The external or relative functions equally connected by their common
destination, connect the individual to every thing that surrounds him;
the sensations, by warning him of the presence of objects which may be

* The classification of the functions which RICHF.RAND adopted, with a slight modifi-
cation from GRJMAUD, nearly agrees with the one more generally followed by the best
modern physiologists. SPREXOKL arranges them into the vegetative, the sensiferous, and
the generative. MAGESIUE divides them into functions of relation, functions of nutrition,
and functions of generation. LENHOSSEK, professor of anatomy and physiology in the

classes the functions into those of

university of Vienna, the latest writer on physiology, classe
organic life, of aenvfermis or animal life, and those belonging

g {.Q generation- — Copland.

useful or injurious to him ; motion, by enabling him to approach, or
avoid such objects, according; as he perceives relations of advantage or
disadvantage, according as the opposite sensations of pain or pleasure re-
sult from his action on them, or from theirs on him. In fine, voice and
speech give him communication with beings enjoying the same means of
communication, and that without a necessity of motion. The brain is the
principal organ of these functions, as thesystem of circulation is the cen-
tre of the assimilating functions. All the impressions received by the
organs of sense are transmitted to the brain, and from the brain, determi-
nations arise, as well as the voluntary motions and the voice. The san-
guineous system receives the molecules destined to nutrition, and those
which are to be thrown out of the body. The sensitive and circulatory
systems are the only systems provided with a centre, (the brain and the
heart) which extend to all parts of the body, by emanations originating
from that organ, or terminating in it (the nerves, the arteries, and veins,):
and, as the motions and the voice depend on sensation, and are immedi-
ately connected with it as necessary consequences, so, respiration, secre-
tion, and nutrition, are, in a manner, but consequences of the circulation
which distributes the blood to all the organs, in order that these may
produce on it various changes which constitute respiration., secretion and
nutrition. They are, to anticipate what is to come hereafter, only differ-
ent kinds of secretion that take place at the expense of the different prin-
ciples contained in the blood.

The circulation which holds the functions of nutrition in a kind of de-
pendence, subjects the brain, which is the principal organ of the external
functions, to an influence still more immediate and indispensable. The
muscular motions are not less under its influence. It is the first function
that is apparent in the embryo, whose evolution it brings about; in natu-
ral death, of all the functions, it is the last to cease. There are many
reasons which justify Haller, for having placed it in the first order, and
for having begun by its history, his great work on physiology. I enter
into this digression, only to expose the absurdity of the claims of some
authors, who, because they have varied the methodical order of the func-
tions, broken the series, or made the slightest changes for example, by
placing the history of the function of smell and taste before the account
of the internal or nutritive functions, think they have totally changed the
aspect of the science: pitiful sophists, who accumulate subleties instead
of facts and ideas.

In warm and red-blooded animals, the nutritive functions, digestion,
absorption, circulation, respiration, the secretions and digestion are per-
formed as in man, and in that respect there exist between them very
slight differences; nay, in some animals, these functions are performed
with much more energy. — Thus several animals digest substances, on
which our own organs produce no effect, and others (birds) have a more
rapid circulation, a more active nutrition, and evolve more heat. But not
one of them is as well provided with organs to keep up intercourse, as a
living being, with the surrounding objects. In no one animal, are the
senses possessed of the same degree of perfection ; the eagle, whose sight
is so piercing, has a very dull sense of touch, taste, and smell. The dog,
whose smell is exquisite, has a very ordinary extent of sight: in him, the
the taste and touch are equally imperfect. — His touch, in the perfection
of which no animal comes up to man, has not been improved in delicacy
at the expense of the other senses. The sight, the hearing, the taste,

64

aud smell, preserve a great delicacy, when their sensibility has not been
impaired by injudicious qr too frequent impressions. The sensitive cen-
tre is in no one better developed, and fitter to direct safely the use of the
organs of motion. No other animal can articulate vocal sounds, so as to
acquire speech.

This greaier extension of life in man, from the number and perfection
of his organs, makes him liable to many more diseases than the other
animals. It is with the human body, as with those machines which be-
come more liable to be deranged, by increasing the number of their wheels,
with a view of obtaining more extensive or more varied effects.

All organized bodies are possessed of assimilating functions ; but as
assimilation requires means varying in number and power, according to
the nature of the being which performs it, the series of assimilating phe-
nomena commences in the plant by absorption, since it draws immediate-
ly from the earth, the juices which it is to appropriate to itself. Its ab-
sorbing system, at the same time, performs the functions of a circulatory
organ, or rather, the circulation does not exist in plants, and the direct
and progressive motion of the sap which ascends from the root towards
the branches, and sometimes in a retrograde course, from the branches,
towards the 'roots, cannot be compared to the circulation of the fluids
which takes place in. man, and in the animals which most resemble him,
by means of a system of vessels which every moment bring back the flu-
ids to the same spot, and convey them over the whole body, by making
them describe a complete circle, frequently, even, a double rotation (ani-
mals with a single or double circulation, that is, whose heart has one or
tv/o ventricles.) Plants breathe after their own manner, and produce a
change in the atmospherical air. by depriving it of its carbonic acid gas,
the result of combustion and of animal respiration, so that by a truly ad-
mirable reciprocity, plants, which decompose carbonic acid, and allow
oxygen to exhale, continually purify the air, which combustion and animal
respiration are incessantly contaminating*.

The functions preservative of the species are common to animals and
plants. The organs by which these functions are performed, when com-
pared in these two kingdoms of nature, offer a resemblance which has
struck all naturalists, and has led them to observe, that of ail these acts
of vegetable life, no one is more analogous to the animal oeconomy, than
that by which fecundatio'n is effected.

* This opinion originated with PHIESTLEY, and was generally adopted, in opposition
to the experience of his cotemporary, the celebrated SCHEELE. Subsequent physiolo-
gists, especially ELLIS, GILBT, and T. DE SAUSSURE, have shown, by well conducted ex-
periments, that all plants, whether growing- in absolute darkness, in the shade, or when
not exposed to the direct rays of the sun, " are constantly removing a quantity of oxygen
from the atmosphere, and substituting- an equal volume of carbonic acid." Thus far
these philosophers nearly agree. They differ, however, very widely respecting the
manner in which this change is effected. ELLIS supposes that the 'leaves, flowers,
fruits, stems, and roots of plants, emit carbonaceous matter, which combines with the
oxygen of the surrounding air. GILBT and SAUSSUHE are of opinion, that the oxygen is
absorbed by the respiratory organs, and that the carbonic acid is formed within the
plant.

Although vegetables, under the ordinary circumstances of their growth, consume oxy-
gen during respiration, and disengage carbonic acid, yet, according as their situation and
particular condition may require, they partially absorb the carbonic acid from the air,
convert it to their use, decompose it, and emit the oxygen which results from the de-
composition, especially when they are exposed to the sun's rays. The illustration of
this subject belongs to vegetable physiology. — Copland,

65

We shall not here explain the general characters of the two orders of
functions which are subservient to the preservation of the species : the
differences which belong to them are pointed out in several parts of this
work*. I shall merely observe with the authors who have considered
them generally, that they are in an inverse ratio to each other, so that, in
proportion as the activity of the assimilating functions increases, that of
the external functions is abated. Grimaud has, in the most complete
manner, illustrated this idea of the constant opposition which exists be-
tween those two series of actions, over which, in the opinion of that phy-
sician, there preside two powers which he calls loco-motive and diges-
tive. It is in no kind of animals more distinct than in the carnivorous,
which possess organs of sense of the greatest delicacy, together with
muscles capable of prodigious efforts, and yet powers of assimilation so
feeble that their food cannot be digested, unless it be composed of mate-
rials analogous in composition to their own organsf.

Too much importance should not be attached to this classification like
all other divisions, it is purely hypothetical. All is connected together,
all is co-ordinate in the animal oeconomy ; the functions are linked toge-
ther, and depend on one another, and are performed simultaneously; all
represent a circle of which it is not possible to mark the beginning or the
end. In circulum abeunt (Hippocrates.) In man, while awake, digestion,
absorption, circulation, respiration, secretion, nutrition, sensation, mo-
tion, voice, and even generation may be performed at the same time ; but,
whoever in the study of the animal oeconomy should bestow his attention
on this simultaneous exertion of the functions, would acquire but a very
confused knowledge of themj.

By becoming familiar with these abstractions, one might soon mistake
them for realities; one might even go the length of seeing two distinct
lives in the same individual ; one would be apt to assign as the character
of internal life, that it is carried on by organs independent of the will.—
Althongh this faculty of the soul presides over the phenomena of respi-
ration, of mastication, of the expulsion of the urine and faeces, one might
consider life as intrusted to unsymmetrical organs, although the heart, the
lungs, and the kidneys, are evidently symmetrical; one might fancy it to

* Especially in the account of living beings, § V. of the Preliminary Discourse ; arti-
cles sleep said fetus. It is impossible at present to go over all these distinctions, without
entering into useless and disagreeable repetitions. — Authors Note.

f In carnivorous animals, the power of digestion is exceedingly weak ; but their mus-
cles are very powerful. This relative force of the muscles was necessary in carnivorous
animals; as they live by depredations and slaughter, as their instinct, 'in unison with
their organization, sets them constantly at war with every thing that has life, and as their
subsistence depends on their being victorious in the battles to which Nature incessantly
calls them. GmMAun/r^ jlfemoir on Nutrition — Author's Note.

t The division which I lay down, is not to be strictly adopted, and as being absolutely
true. It is a mere hypothesis to be attended to, only in so far as it assists in arranging
one's ideas in a more orderly manner. For, every arrangement, even when arbitrary,
is useful in laying before us a great number of ideas, and in thereby facilitating the com-
parison that is to be instituted among them. All the acts of Nature are so connected,
and are linked together in so close an union, and she passes from the one to the other,
by such uniform motions, and by gradations so insensible and so adjusted, as to leave
no space rbr us to lay down the lines of separation, or demarcation, which we may
choose to draw. All our methods of classing and arranging the productions of Nature,
are mere abstractions of the mind, which does not consider things as they really are,
but which attends to certain qualities, and neglects or rejects all the rest.
Lectures on Plntsiol*:?". — Jluthr>ryfs Note.

66

exist in the foetus, which neither breathes, nor digests', £c. Nothing in
the animal oeconomy, said Galen, is ruled by invariable laws, or can be
subject to the same accurate results and calculations, as an inanimate ma-
chine, (Nilestin corpore viventi filane sincerum. GALEN.) Thus, respiration,
which connects the external and assimilating function, furnishes the blood
with the principle which is to keep up the action of the brain, and to ex-
cite musculai contractions. On the other hand, the motion of the mus-
cles is of use in the distribution of the humours, and concurs in the phe-
nomena of assimilation. The brain, by means of the eighth part of nerves,
holds influence over the stomach. The sensations of taste and smell seem
to preside, in an especial manner, over the choice of food and of air, and
to belong rather to the digestive and respiratory functions, than to those
of the intellect, or of thought.

We have seen in this kind of general introduction of the study of phy-
siology, what idea is to be formed of that science as well as of life, the
study of which is its object ; into how many classes the beings in nature
may be divided, and into how many elements they are resolvable; what
differences exist, between inorganized, organized and living bodies,
between plants and animals; how life is complicated, modified, and ex-
tended, in the immense series of beings which are endowed with it, from
the plant to man ; anc4 in further particularizing the object under our
consideration, we have examined, what are the organs which, by their
union, form the human machine ; what powers govern the exercise of
their functions : then, we have laid down the fundamental laws of sensi-
bility and contractility, we have spoken of sympathies and habits, of the
internal nervous apparatus, which unites, collects, and systematizes the
organs of the assimilating function ; we have endeavoured to determine
from facts, the existence of the cause which subjects living beings to a
set of laws very different from those which inorganic matter obeys. The
knowledge of these laws is the light which is to guide us in the applica-
tion to physiology of the accessory sciences. Finally, in the arrangement
of the objects which this science considers, I have adopted a more sim-
ple and natural division than any hitherto employed.

I shall close this preliminary discourse, by saying a few words on the
order adopted in the distribution of the chapters. I might have begun by
a view of the external functions, as well as those of assimilation or nutri-
tion, of sensation, or of digestion. I have given preference to the func-
tions of assimilation, because of all others, they are the most essential to
existence, and their exercise is never interrupted, from the instant in
which the embryo begins to live, till death. In beginning, with an ac-
count of them we imitate nature therefore, who imparts to man this mode
of existence, before she has connected him with outward objects, and who
does not deprive him of it, until the organs of sense, of motion, and of
the voice, have completely censed to act.

As to the course which has been followed in the arrangement of the
functions that belong to the same order, or which concur in the same end,
it was too well laid down by nature, to .allow us to depart from it. I have*
thought it right that the consideration of the voice should immediately
precede that of generation, in order that the arrangement might, at a
glance, show the connexion which exists between their phenomena. —
Several animals us.e their voice only during the season of love ; the birds
which sing at all times have, during that period, a more powerful and so-
norous voice. When man becomes capable of reproduction, his vocal

67

organs suddenly become evolved, as though nature had wished to inform
him, that it is through them he is to express his desires to the gentle be-
ing who may sympathize in them. The voice, therefore, serves as a na-
tural connexion between the external functions, and those which are em-
ployed in the preservation of the human species.

The voice, which leads so naturally from the functions which establish
our external relations, to those whose end is the preservation of the spe-
cies, is still more intimately connected with motion. It is, in a manner,
the. complement of the phenomena of locomotion ; by means of it, our com-
munication with external objects is rendered easier, more prompt, and
more extensive : it depends on muscular action, and is the result of vo-
luntary motion. Finally, these motions sometimes supply the place of
speech, in pantomime, for example, and in the greater number of cases,
the language of action concurs in adding to its effect. Every thing-, there-
fore, justifies me in placing this function after motion, in separating it
from respiration, with which every other author has joined it, without
considering that the relation between the voice and respiration is purely
anatomical, and can, therefore, in nowise apply to physiology.

I have placed after generation, an abridged account of life and death,
in which will be found, whatever did not belong to any of the preceding
divisions. The necessity of this appendix, containing the history of the
different periods of life, that of the temperaments and varieties of the hu-
man species, that of death and putrefaction, arises from the impossibility
of introducing into the particular history of the functions, these general
phenomena in which they all participate.

.FIRST CLASS.

LIFE OF THE INDIVIDUAL,

FIRST ORDER.

FUNCTIONS OF ASSIMILATION,

OB, JTTKCTIOSrS WHICH ABE SUBSBBVIENT TO THE PBESEBVATIOW Ofc TH£
INDIVIDUAL, Bt ASSIMILATING TO HIS SUBSTAJTCEfHi: JOOI>
BY WHICH HE IS HQUBISHEID

NEW ELEMENTS

OF

PHYSIOLOGY

CHAPTER I.

OF DIGESTION.

I. Digestion is a function common to all animals, by which substances
extraneous to them, are introduced into their body, and subjected to the
action of a peculiar system of organs, their qualities altered, and a new
compound formed, fitted to their nourishment and growth.

II. General considerations on the Digestive organs. Animals alone are
provided with organs of digestion ; all of them, from man down to the
polypus, contain an alimentary cavity, variously shaped. The existence
of a digestive apparatus may, therefore, be taken as the essential charac-
teristic of the animal kind. In man, this apparatus consists of a long tube
extending from the mouth to the anus ; within this canal, there empty
themselves the excretory ducts of several neighbouring glands, that secrete
fluids fit for changing, for liquefying, and animalizing the alimentary sub-
stance. The different parts of this digestive tube are not of equal capaci-
ty; at first, enlarged in the part whjch forms the mouth and pharynx, it
becomes narrower in the oesophagus; this last, dilating considerably,
forms the stomach, which again contracting, is continued down under the
name of intestine. The tube itself varies in size in different parts of its
extent: and it is by the consideration of these differences of size, that
anatomists have principally been guided in their divisions.

The length of the digestive tube is from five to six times the length of
the whole body, in an adult: it is greater in proportion in a child. At
this age, likewise, digestion is more active, and proportioned to the ne-
cessities of growth in the individual. The digestive cavity is in man open
<it both extremities ; in some animals, in the zoophyte for example, one
opening serves the purpose of mouth and of anus, receives the food, and
ejects the excrementitious remains.

The extent of the digestive canal is according to the nature of the ali-
ments on which the animals feed : the less those aliments are analogous
in their nature to the substance of the animal they are to nourish,
the longer must they remain in his body to undergo the necessary changes.
Therefore, it is observed, that the intestine of graminivorous animals is
very long, their stomach very capacious, and often complex, while carni-
vorous animals have their intestinal canal short and strait, and so arranged,

72

that the animal substances which are most nourishing, in least bulk, of
easy and rapid digestion, which, by too long a stay in the intestines,
might become putrid, pass readily through it. In this respect, man holds
a middle station between those animals which feed on vegetables, and
those which feed on animal substances. He is, therefore, equally fitted
for these two kinds of food; he is neither exclusively herbivorous, nor
nor carnivorous, but omnivorous or polyphageus. This question, of such
easy solution, has long employed physicians, naturalists, and philoso-
phers; each bringing, in favour of his opinion, very plausible arguments,
drawn from the form and number of the teeth, from the length of the in-
testinal canal, from the force of its parietes, 8tc.

The parietes of the digestive tube are essentially muscular; a mucous
membrane lines its inside, forming within it various folds ; lastly, a
a third coat is accidentally placed over the other two ; and is furnished
by the pleura to the oesophagus, by the peritoneum to the stomach, as
well as to the intestinal canal.

The characteristic of this third coat is, that it does not cover the whole
surface of the parts of the tube to which it is applied. The muscular coat
may be considered as a long hollow muscle, extending from the mouth to
the anus, and formed throughout almost all the whole of its length, by two
layers of fibres, the one set longitudinal, the other circular. The will di-
rects the motions of the two extremities, while the rest of its course is
not under its controul. In the cells of the tissue which unites its surfaces
to the other coats, fat never accumulates, which might have impeded its-
contractions, and straitened and even obliterated the tube along which the
food was to pass*.

III. Of food, solid and liquid. The aliments which nourish man are ob-
tained from vegetables, or from animals. The mineral kingdom furnishes
only condiments, medical substances, or poisonsj.

By aliment is meant whatever substance affords nutrition, or whatever
is capable of being acted upon by the organs of digestion. Substances
which resist the digestive action, those which the gastric juice cannot
sheathe, whose asperities it cannot soften down, whose nature it catvnot
change, possess to a certain degree the power of disturbing the action of
the digestive tube, which revolts from whatever it cannot overcome: there
is no essential difference between a medical substance and a poison. Our
most active remedies are obtained from among the poisonous substances;
tartar emetic, corrosive sublimate, opium, all of them remedies of so
much efficacy in skilful hands, when administered unseasonably, or in too

* The digestive tube comprehends, 1. the mouth ; 2. the pharynx ; 3. the oesopha-
gus; 4. the stomach; 5. the small intestines; 6. the large intestines; 7. the anus. The
commencement and termination of this apparatus are subjected, but not completely,
to the influence of the will. Volition and sensation are distinctly evinced in the mouth
and pharynx ; in the oesophagus and stomach the influence of the will gradually disap-
pears, and sensation becomes imperfect and peculiar. It is in consequence of the dis-
tribution of voluntary nerves, in greater or less number, to certain parts of the digestive
canal, and of the accession thus brought to the ganglial system of nerves with which it
is chiefly supplied, that many of the sensations and operations which belong to its upper
portion,'as the pharynx, oesophagus and the stomach, are so peculiar, and so difficult of
explanation. — Copland.

\ MACKNJUE arranges the aliments which nourish man according to the immediate
principle which predominates in their composition. After this manner he distinguishes
nine classes; namely, farinaceous, mucilaginous, saccharine, acidulated, oleaginous,
milky or cheesy, gelatinous, album: nous. f>Tv! lihrinous pTim.i'nts — Copland,

73

g-trong doses, act as most violent poisons; they forcibly resist the diges-
tive powers, and furnish them nothing to be acted upon, while mild and
inert substances yield to these powers, and come under the class of ali-
ments. What then is to be thought of our ptisans, of chicken and veal
broth, and other such remedies? That they are employed to deceive the
hunger and thirst of the patient, to prevent his receiving into his stomach,
substances whose laborious digestion would take up the strength requir-
ed for the cure of the disease; that they are mere precautions'of regimen,
that he who most varies this kind of resource, can only be said to adopt
a treatment of expectation, leaving to nature alone, the care of exciting
those salutary motions which are to bring about a cure. Why do cer-
tain vegetable purgatives, as manna and tamarinds, produce so little ef-
fect, even though given in large doses? Because these substances contain
many nutritious particles capable of being assimilated, so that strong
constitutions digest them, and completely neutralize their irritating or
purgative qualities. An animal or vegetable substance, though essential-
ly nutritious, may act as a medicine, or even as a poison, when, in con-
sequence of the extreme debility of the digestive tube, or because it has
not been sufficiently divided by the organs of mastication* it resists the
digestive action. Thus surfeits are brought on because the stomach is
debilitated, because it is oppressed by too great a mass of substances, or
because, having been imperfectly triturated, they are insoluble. It is in
considerations of this kind, that the true foundations of materia medica
are laid.

Mineral substances are of a nature too heterogeneous to our own, to ad-
mit of being converted into our substance. It appears that their elements
require the elaboration of vegetable life; hence, it has been justly ob-
served, that plants are laboratories in which nature prepares the food of
animals.

Aliments obtained from plants are less nutritious than those furnished
by the animal kingdom, because in a given bulk, they contain fewer parts
that can be assimilated to our own substance. Of all the parts of vegeta-
bles, the most nourishing is their amylaceous fecula, but it yields the
more readily to the action of the digestive organs, from having already
experienced an incipient fermentation ; on that account, leavened bread
is the best of vegetable aliments. The flesh of young animals is less
nourishing than that of the full grown, although, at an early age, the flesh
of the former abounds more in gelatinous juice's; for, this abundant gela-
tine wants the necessary degree of consistence.

However various our aliments may be, the action of our organs always
separates from them the same nutritious principles ; in fact, whether we
live exclusively on animal or vegetable substances, the internal composi-
tion of our organs does not alter; an evident proof, that the substance
which we obtain from aliments, to incorporate with our o\\n, is always
the same, and this affords an explanation of the saying of the father of
physic, " There is but one food, but there exist several forms of food,"

Attempts have been made to ascertain the nature of this alimentary
principle, common to all nutritive substances, and it is conjectured, with
some probability, that it must be analogous to gummy, mucilaginous, or
saccharine substances ; they are all formed from hydrogen and carbon, are
well known to differ chemically only in the different proportions of oxy-
gen which they contain. Thus, sugar is a kind of gum, containing a con-
siderable quantity of oxygen; and which is reduced, in a certain degree,

K

74

to the state of starch, when brought lo fine powder by means of a rasp,
for, the friction disengaging a portion of its oxygen, deprives it in part of
its flavour, and leaves it an insipid taste, similar to that of farinaceous
substances. Nothing, in fact, nourishes better, more quickly, and from
a similar bulk, than substances of this kind. The Arab crosses the vast
plains of the desert, and supports himself by swallowing a small quantity
of gum arabic. The nourishing quality of animal and vegetable jellies is
well known'; saccharine substances soon cloy the appetite of those who arc
fondest of them: In decrepid old age, some persons live exclusively on
sugar; I know several in that condition, who spend the day in chewing
this substance, which is a laborious employment for their feeble and
toothless jaws*. Lastly, milk, the sole nourishment of the early periods
of life, contains a great proportion of gelatinous and saccharine matter.

Though man, destined to live in all latitudes, is formed to subsist on
all kinds of food, it has been observed, that the inhabitants of warm cli-
mates generally prefer a vegetable dietf. The Bramins in India, the in-
habitants of the Canary Islands, and of the Brazils, Sec. who live almost

* MAGEXIUE concluded from his experiments, that no animal seems capable of deriv-
ing nutriment from any substance that does not contain some portion of azote. There
are, however, many circumstances which prove the contrary — ADAXSOX asserts, that
the Nomadie Moors have scarcely any other food than gum Senegal. HASSEL<VUIST re-
lates, that a caravan of Abyssinians, consisting of 1000 persons, subsisted for two months
on a stock of gum arabic alone, which they found among1 their merchandize ; and it is
well known, that negroes, and individuals otherwise imperfectly fed, soon become fat
from the mastication of the sugar-cane. A case lately came under our observation,
which fully exemplifies the nutritious quality of sugar, in a lady, about the middle age,
who consulted us respecting great and increasing corpulency. Her countenance was
full, clear, and florid; her pulse strong; her health excellent; and her strength very
considerable. She partook of animal food only once in a day, and then in a small quan-
tity. She never took suppers, and WHS very moderate in the use of fluids. She had al-
ways taken considerable exercise on foot, and even up to the period at which we saw
her, she resorted to it as much as the great bulk of her body could permit. The secret,
however, of her increasing obesity was disclosed, when she mentioned her insatiable de-
sire for refined sugar, which she almost hourly made use of, frequently to the extent of
one pound we'.ght daily. She considered it her chief article of diet. She reckoned the
average quantity which she used at about three-fourths of a pound in the day. Tea or
coii'ce was taken by her sweetened in the usual way. She ate the sugar in the solid state,
and unaccompanied with any other article of diet : the finest sort only was relished.
Her digestive functions were in a perfect condition ; neither cardialgia, acidity, nor fla*
tidence, were complained of. Her teeth were sound. She found her corpulence super-
vene to a spare habit some time after the habit of eating sugar was acquired. She
thought that the obesity increased with the increase in the quantity of sugar she consum-
ed. The habit had become so confirmed, at the time which We saw her, that she con-
ceived it to be quite impossible to relinquish it. — Copland.

-j- These inhabitants of warm climates, who are subjected, in consequence of the na-
ture of the situation in which they live, to a moist and miasmatous atmosphere, generally
adapt their vegetable diet, as much as may be in their power, to the circumstances in
which they are placed. They endeavour, by adding a large proportion of the stimulant
and tonic seeds of plants to their aliments, to counteract the debilitating and septic in-
fluence of the air which they breathe, and to other causes to which they are more or less
opposed. To them the hot spices are the chief condiment, and even prophylactic ;
without the use of these, their very aliments would become a source of disease ; the
various kinds of parasitical animals, which prey on man, would abound to the most
loathsome degree, and they would be continually the subject of dysentery, and the
other diseases which imperfect or improper nourishment and an unwholesome climate
induce. The hot spices are, to individuals so circumstanced, more requisite than salt
is to the inhabitants of temperate or cold ctimates, who live chiefly on animal food,-^
Copland,

75

exclusively on herbs, grain, and roots, inhabit a climate, against the ex
cessive heat of which they have to seek means of protection ; now, the
digestion of vegetables is attended with less heat and irritation. The
philosophical or religious sects, by which the abstinence from the animal
food was <3^^Hered a meritorious act, were all instituted in warm cli-
mates. The school of Pythagoras flourished in Greece, and the ancho-
rets, who, in the beginning of the Christian religion, peopled the solitudes
of Thebais, could not have endured such long fastings, or supported them-
selves on dates and water, in a more severe climate. So that the monks
that removed into different parts of Europe, were obliged to relax
from the excessive severity of such a regimen, and yielded to 'the irre-
sistible influence of the climate; the most austere came to add to vege-
tables, which formed the base of their food, eggs, butter, fish, and even
water-fowl. In books of casuistry, it may be seen, on what ridiculous
grounds there was granted a dispensation in favour of plovers, of water-
hens, wild ducks, snipes, scoters, birds whose brown flesh, more animal-
ized, and more heating, ought to have been proscribed from the kitchen
of monasteries, much more strictly than that of common poultry.

Consider what is the alimentary regimen of the different nations on the
face of the earth, and you will see, that a vegetable diet is preferred by the
inhabitants of warm countries: to them, sobriety is an easy virtue; it is
a happy consequence of the climate. Northern nations, on the contrary,
are voracious from instinct and necessity. They swallow enormousquan-
tities of food, and prefer those substances which in digestion produce the
most heat. — Obliged to struggle incessantly against the action of cold,
which tends to benumb the vital powers, to suspend every organic mo-
tion, their life is but a continual act of resistance to external influences.
Let us not reproach them with their voracity, and their avidity for ardent
spirits and fermented liquors. Those nations that inhabit the confines of
the habitable world, in which man is scarcely able to withstand the seve-
rity of the climate, the inhabitants of Kamtschatka, the Samoiedes, live
on fish, that in the heaps in which they are piled up, have already under-
gone a certain degree of putrefactive fermentation. Does not the use of a
food so acrid and heating, that in our elimate it would inevitably be at-
tended with a febrile action, prove plainly the necessity 'of balancing, by a
vigorous inward excitement, the debilitating influence of powers that are
operating from without? The abuse of spirituous liquors is fatal to the
European transported to the burning climate of the West Indies. The
Russian drinks spirituous liquors with a sort of impunity, and lives on to an
advanced age, amidst excesses under which an inhabitant of the south of
Europe would sink.

This influence of climate affects alike the regimen of man in health, and
that of man in sickness, and, it has been justly observed of medicine, that
it ought to vary according to the places in which it is practised. Barley,
ptisan, honey, and a few other substances, the greater part obtained from
the vegetable kingdom, sufficed to Hippocrates in the treatment of dis-
eases, his therapeutic treatment was, in almost every case, soothing and
refreshing. Physicians, who practise in a climate such as that of Greece,
may imitate this simplicity of the father of physic. Opium, bark, wine,
spirits, aromatics, and the most active cordials, are, on the other hand,
the medicines suited to the inhabitants of the North. The English phy-
sicians use, freely and without risk, these medicines, which elsewhere
would be attended with the utmost danger.

To

Simple aqueous drinks promote digestion, by facilitating the solution
of the solids; by serving as a vehicle to their divided parts; and when
rendered active by saline or other substances, as spirituous liquors are by
alcohol, they are further useful in stimulating the organs, and exciting
their action.

The least compound drinks are possessed, in different degrees, of this
double property of dissolving solid aliments, and of stimulating the diges-
tive organs. The purest water is rendered stimulating by the air, and by
the salts which it contains, in different proportions; and, to the want of
that stimulating quality is to be attributed the difficult digestion of dis-
tilled water.

The drinks best suited to the wants of the animal economy, are those
in which the stimulating principles are blended, in due proportions, with
the water which holds them in solution. But almost all the fluids which
we drink, contain a certain proportion of nutritious particles. Wine, for
example, contains these nutritive particles in greater quantity, as it is the
produce of a warmer climate, and as saccharine matter predominates in
its composition. Thus, Spanish wines are in themselves nourishing, and
are perhaps fitter to satisfy hunger than to allay thirst, while the acidu-
lous Rhenish wines, which are merely thirst allaying, scarcely contain
any cordial quality. Between the two extremes are the French wines,
which possess, in a nearly^equal degree, the treble advantage of diluting
the fluids, of stimulating the organs, and of furnishing to the animal eco-
nomy materials of nutrition.

IV. Of hunger and thirst. By the words hunger and thirst are meant two
sensations, which warn us of the necessity of repairing the loss which our
body is continually undergoing from the action of the vital principle.—
Their nature, as is well observed by M. Gall, is not better known than
that of thought. Let us endeavour to explain the phenomena by which
they are attended.

The effects of a protracted abstinence are, a diminution of the weight
of the body, a dimunition which becomes sensible in the course of twenty-
four hours 5 a wasting of the body from the loss of fat, discoloration of
the fluids, especially the blood, loss of strength, excessive sensibility,
sleeplessness, with painful sensations in the epigastric region*.

Death from inanition is most easily brought on, in those who are young
and robust. Thus, the unfortunate father, whose horrible story has been
related by Dante, condemned to die of hunger, and shut up with his chil-
dren in a dark dungeon, died the last, on the eighth day, after having wit-
nessed, in the convulsions of rage and despair, the death of his four sons,
unhappy victims of the most execrable vengeance every recorded in the
history of man. Haller has related, in his great work on physiology,
several instances of prolonged abstinence : if we are to give credit to
these accounts, some of which are deficient in the degree of authenticity
required to warrant belief, persons have been known to pass eighteen
months, two, three, four, five, six, seven, and even ten years, without ta-
king any nourishment. In the Memoirs of the Edinburgh Society is
found the history of a woman who lived on whey only for fifty years. The
subjects of these cases are mostly weak, infirm women, living in obscuri-
ty and inaction, and in whom life, nearly extinct, just showed itself in an

* See APPENDIX. Note 1.

almost insensible pulse, an unfrequent and indistinct respiration. It is a
iact well worthy of observation, that the muscles and viscera of some of
them, when examined after death, shone with a light evidently phospho-
ric*. Can it he that phosphorus is the result of the lowest degree of ani-
rndization? It may be easily conceived, that living in a manner, on their
own substance, the fluids in such persons have been frequently subjected
to the causes which produce assimilation and animaiization, and have un-
dergone the greatest alteration of which they are capable.

The proximate cause of hunger has by some been conceived to depend
on the friction of the nervous papillae of the empty stomach on each other;
by others, it has been imputed to the irritation produced on its parietes,
by the accumulation of the gastric juice. It has been thought to depend
on the lassitude attending the permanent contraction of the muscular
fibres of the stomach ; and on the compression and creasing of the nerves,
during that permanent constriction; on the dragging down of the dia-
phragm by the liver and spleen, when the stomach and intestines being
empty, cease to support those viscera: a dragging which is the greater,
as a new mode of circulation takes place in the viscera, which are sup-
plied with blood by the caeliac artery, and while the stomach receives less
blood, the spleen and liver increase in weight and size, because their sup-
ply is increasedf.

Those who maintain that hunger depends on the friction of the pari-
etes of the stomach against each other, when brought together in an
empty state, adduce the example of serpents, whose stomach is purely
membranous, and who endure hunger a long time, while fowls, whose
powerful and muscular stomach is able to contract strongly on itself, en-
dure it with difficulty. But to say nothing of the great difference of
vitality, in the organs of a bird and of a reptile, the stomach which con-
tinues closing on itself as it is emptied, may contract to such a degree as
scarcely to equal in size a small intestine, without its following, as a ne-
cessary consequence, that the parietes which are in contact should exert
on each other any friction, on which the sensation of hunger may depend.

* Nitidissima viscera sunt animalium fame enectorum, ei argcntei Jibrarum fasiculi.-—
JUiiEB, Elem. Phys. torn. VI. page 183.

\ The most prevalent opinions respecting the proximate causes of hunger are, that it
is owing to the action of the gastric juice on the stomach, or that it is a sensation con-
nected with the contracted state of this organ and the corrugation of its internal mem-
brane. It is not unlikely that both causes may contribute to the production of this sen-
sation, in consequence of the impression which they make on the sentient extremities
of these cerebral nerves which reinforce the vital operations of the stomach. The state
of the absorbent vessels, and the irritation which the gastric fluid induces on the ex-
tremities of these vessels, during an empty state of this viscus, ought also to be taken
into consideration in our speculations respecting the origin of this sensation.

The following experiment of Dr. \V. PHILIP, detailed in his excellent work on indi-
gestion, appears to confirm the opinion that the influence of the gastric juice on the
stomach is, in some way or other, productive of the sense of hunger.

" A person in good health was prevailed upon to abstain from eating for more than
twenty hours, and further to increase the appetite by more exercise than usual. At the
end of this time he was very hungry ; but, instead of eatine:, excited vomiting by drink-
ing; warm water, and irritating the tauces. The water returned mixed only with a ropy
fluid, such as the gastric fluid is described to be by Spallanzani, or as I have myself ob-
tained it from the stomach of a crow. After this operation, not only all desire to eat was
removed, but a degree of disgust was excited by seeing- others eat. He, however,, was
prevailed upon to take a little milk and bread, which in a very short time ran into the
acetous fermentati oh, indicated by flatulence and acid eructations." — Copland.

TS

In fact, the presence cf food is necessary to determine an action fcf the
parietes of the stomach, and as long as it is empty, there is nothing to
call forth such action.

Those who think that hunger is mechanically produced by the weight
of the spleen and liver that keeps pulling down the diaphragm, which the
empty stomach no longer bears up, observe, that it may be appeased, for
a time, by supporting the abdominal viscera by means of a tight girdle ;
that hunger ceases as soon as the stomach is full, before the food can
have yielded to it any materials of nutrition. On this hypothesis, which
is purely mechanical, as that which explains hunger by the irritation of
the gastric juice, by the lassitude of the contracted muscles, by the com-
pression of the nerves, how shall we explain the fact, that when the hour
of a meal is over, hunger ceases for a time ? Ought not hunger, on the
contrary, to be considered as a nervous sensation which exists in the sto-
mach, is communicated by sympathy to all the other parts, and keeping
up an active and continuous excitement in the organ in which it is prin-
cipally seated, determines into it the fluids from all parts ? This pheno-
menon, like all those which depend on nervous influence, is governed by
the laws of habit, by the influence of sleep, and of the passions of the
mind, whose power is so great, that literary men, absorbed in meditation
and thought, have been known entirely to forget that they required food.
Every thing which awakens the sensibility of the stomach, in a direct or
sympathetic manner, increases the appetite, and occasions hunger. Thus,
bulimia depends, sometimes, on the irritation of a tape-worm in the or-
gans of digestion. The application of cold to the skin, by increasing,
from sympathy, the action of the stomach, has been known to "occasion
fames canina^ of which several instances are related by Plutarch (Life of
Brutus.) Ardent spirits and highly seasoned food, excite the appetite,
even when the stomach is overfilled. Whatever, on the contrary,
blunts or renders less acute the sensibility of the stomach, renders more
endurable or suspends the sensation of hunger. Thus, we are told by
travellers, that the Turkish dervises and the Indian faquirs, endure long
fasts, because they are in the habit of using opium, and lull, in a manner,
by this narcotic, the sensibility of the stomach. Tepid and relaxing
drinks impair the appetite; the use of opiates suspends suddenly the ac-
tion of the stomach.

V. OfThirtt. The blood deprived of its serosity, by insensible per-
spiration and by internal exhalation, requires incessant dilution, by the
admixture of aqueous parts, to lessen its acrimony; and as the serosity
is incessantly exhausting itself, the necessity for repairing that loss is ever
urgent*. The calls of thirst are still more absolute than those of hunger,

* As hunger seems to depend upon a certain condition of, or impression made upon,
these cerebral nerves distributed to the stomach, so thirst appears to arise from an alter-
ed state of the fluids, which state modifies the functions of the vessels, diminishes or
otherwise alters the condition of the fluids secreted in the mouth and fauces, and im-
presses the nerves of sensation, in these situations, in such a manner as to give rise to
tiie phenomenon under consideration.

As the sense of thirst is induced by a state of the circulating fluids, which would be-
come hurtful to the system were it to continue for any .considerable period, so this sen-
sation is to be.regarded in the light of a watchful guardian, which both points out that
state, and the only way in which it can be removed.

The super-abundance of saline or stimulating substances in the blood, is readily indi-
cated by the sensation induced in the mouth and fauces, which are the first, parts to

79

and it is much less. patiently endured. If it be not satisfied, the blood, and
the fluids which are formed from it, become more and more stimulating,
from the concentration of the saline and other substances which they con-
tain. The genera! irritation gives rise to an acute fever, with heat and
parching of the fauces, which inflame, and may even become gangrenous,
as happens in some cases of hydrophobia. English sailors, who were
becalmed, had exhausted all their stock of fresh water, and were at a dis-
tance from land; not a drop of rain had for a long time cooled the at-
mosphere: after having borne, for some time, the agonies of thirst, fur-
ther increased by the use of salt provisions, they resolved to drink their
own urine. This fluid, though very disgusting, allayed their thirst; but
at the end of a few days, it became so thick and acrid, that they were in-
capable of swallowing a mouthful of it. Reduced to despair, they expect-
ed a speedy death, when they fell in with a ship which restored them to
hope and life. Thirst is increased every time that the aqueous secretions
are increased; thus, it becomes distressing to a dropsical patient, in
whom the fluids are determined towards the seat of effusion. It is ex-
cessive in diabetes, and in proportion to the increased quantity of urine.
In fever, it is increased, from the effect of perspiration, or because in
some of these affections, for example in bilious fevers, the blood seems
to become more acrid. Hence the advantage of cooling, diluting, and
refreshing drinks, administered copiously, with a view to correct the
temporary acrimony occasioned by the absence of a great quantity of the
serous parts of the blood, and to lessen the over excitement of a fluid be-
come too stimulating.

The use of aqueous drink is not the most effectual method of allaying
thirst. A traveller exposed to the scorching heat of summer, finds it ad-
vantageous to mix spirits to plain water, which alone does not stimulate
sufficiently the mucous and salivary glands, whose secretion moistens
the inside of the mouth and pharynx, and covers these surfaces with the
substance best calculated to suspend, at least for a time, the erethism on
which thirst appears to depend.

VI. On Mastication*. The organs employed in the mastication of the
food, are the lips, the jaws, and the teeth; with these are furnished, the
muscles by which they are moved, and those which form the parietes of
the mouth. The motions of the lips are extremely varied, and depend on

evince the deleterious effects of these substances upon the animal economy : hence the
state of these organs is an important index to the condition of the circulating fluids, and
of the whole system, in a number of diseases.

Those physiologists who refer the operations of the livingbody to a galvanic process,
carried on by the nervous system on the fluids contained in the vascular, especially in
the capillaries, assign, as the proximate causes of thirst, a deficiency of oxygen and an
abundance of the inflammable materials amongst these elements which constitute the
fluids circulating at the time in which the sensation is induced, (" Oxygenii autem de-
fectum et phlogisticorum abundantium sitim adducere.") This, or a similar opinion, is
entertained by SPHENGEI,, PROCHASKA, BCIIBACH, and LENHOSSECK. The arguments
which these systematic writers on physiology adduce, as well as the experiments of
Dr. PHILIP, in support of the theory which ascribes the vital phenomena to galvanic
processes taking place in the system, deserve to be calmly considered before they are
designated to be either visionary or untenable. Copland.

* The following operations are comprehended under the process of digestion, name-
ly, 1. mastication ; 2. insalivation ; 3. deglutition ; 4. the action of the stomach ; 5. the
action of the small intestines; 6. the action of the large intestines; 7. the expulsion of
the faeces — Copland,

80

the single or combined action of their muscles, by which the greater part
of the face is covered, and which may be enumerated as follows : — Eleva-
tors of the upper lip (caninus, incisvus, leva-tores communes labiorum el my-
rtiformes.} Depressors of the under lip (triangularis labiomm, quadratus
genx.) Abductors (buccinator, zygomaticus major et minor ^ platysma
myoides.} Constrictors (orbicularis or is.}

VII. The motions of the upper jaw are so confined, that some have de-
nied that it has any motion: it nevertheless rises a little*, when the low-
er jaw descends; but it is principally by the depression of the latter that
the mouth is opened. The muscles at the back of the neck, and that part
of the digastric muscle nearest the mastoid process, produce a slight ele-
vation of the upper jaw, which moves with the whole head, to the bones
of which it is firmly united. This connexion of the upper jaw with the
bones of the head, renders this jaw less move able in man than in the
greater number of animals, in which, freed from the enormous weight of
the skull, it stretches out in front of that cavity, over the lower jaw. As
we follow downwards the scale of animal existence, the motions of the
upper jaw is seen to increase, the further we descend from the human
species; it is equal to that of the lower jaw, in the reptiles, and in several
fishes : hence the enormous dimensions of the mouth of the crocodile and
shark; hence serpents frequently swallow a prey of a bulk greater than
their own, and would be stiffocated, but for the power they possess, of
suspending respiration for a long time, and of waiting patiently, till the
gastric juice dissolves the food, as it is swallowed.

In the act of mastication, the upper jaw may be considered as an anvil,
on which the lower jaw strikes as a moveable hammer, and the motions
of the under jaw, the pressure it exerts, and its efforts, would soon have
disturbed the connexion of the different bones of which the face is formed,
if this unsteady edifice, merely formed of bones, in juxta position, or
united by sutures, were not supported, and did not transmit to the skull,
the double effort which presses on it from below upwards, and pushes it
out literally. Six vertical columns, the ascending apophyses of the supe-
rior maxillary bones, the orbital* processes of the malar bones, and the
vertical processes of the palate bones, support and transmit the effort
which takes place in the first direction, while the zygomatic processes
forcibly press the bones of the face against each other, and powerfully re-
sist separation outwardly or laterally. The lower jaw falls by its own
weight, when its elevators are relaxed; the external pterygoid muscles,
and those attached to the os hyoides, complete this motion, the centre of
which is not in the articulation of the jaw to the temporal bones, but cor-
responds to a line that should cross the coronoid processes, a little above
the angles of the jaw. It is around this axis, that, in falling, the lower
jaw performs a motion of rotation, by which its condyles are turned for-
wards, while its angles are carried backwards. In children, the coro-
noid processes standing off at a smaller distance from the body of the
bone, of which they have nearly the same direction, the centre of motion
is always in the glenoid cavities, which the condyles never quit, however
much the jaw may be depressed. By this arrangement, nature has guard-
ed against dislocation, which would have been frequent at an early period

* This can only be from a motion of the whole head on the atlas ; the action of the
posterior belly of the digastricus is a mere assumption.— Godman>

81

of life from crying, during which, the jaw is depressed beyond measure,
or when not knowing the just proportion between the capacity of the
mouth, and the size of the bodies they would put into it, children endea-
vour to introduce those which it cannot receive. The lower jaw forms
a double bended lever of the third kind, in which the power, represented
by the temporal, masseter and internal pterygoid muscles, lies between
the fulcrum and the resistance, at a smaller or greater distance from
the chin.

The mode of articulation of the jaw to the temporal bones, allows it
only a motion upwards and downwards, in which the teeth of both jaws
meet like the blades of scissars, and a lateral motion* in which the teeth
glide on each other, producing a friction well calculated to grind the food,
which in the first part of the act of mastication was torn or divided.

VIII. In carnivorous animals, the levator muscles of the under jaw,
especially the temporals and massetcrs, are prodigiously large and pow-
erful. In them, the coronoid processes, to which the temporal muscles
are attached, are very prominent; the condyles are received into a very
deep cavity ; while in herbivorous animals, on the contrary, they are less
strong and bulky, and the pterygoid muscles, by whose action the lateral
or grinding motion is performed, are stronger and more marked. The
glenoid cavities are also in them wide but shallow, so that they allow the
condyles to move freely on their surface. The comparative power of the
levator and abductor muscles of the lower jaw, may be easily appreciated,
by viewing the temporal and zygomatic fossse. Their depth is always in
an inverse ratio, and proportioned in the bulk of the muscles which they
contain. In carnivorous animals, the zygomatic arch, to which the mas-
seter is attached, is depressed, and seems to have yielded to the effort of
the muscle. In the point of view which we have just taken, man holds a
middle station between carnivorous animals and those which feed on ve-
getable substances ; nothing, however, determines his nature better than
the composition of his dental arches.

IX. The small white and hard bones which form the dental arches, are
not alike in the animals whose jaws are furnished with them. All have
not, as man, three kinds of teeth. The laniary* teeth are not to be met
with, in the numerous class of rodentia, Some are without incisors; the
former appear more fitted to tear fibrous tissues which offer much resist-
ance. In carnivorous animals, they are likewise very long, and bent like

* After the example of several naturalists, I have thought it right to give that name to
the canine teeth ; in the first place, because their principal use being to lacerate or
tear fibrous tissues, it is fit that they should have a name from their manner of acting on
the food, as is the case with the incisors and molares ; in the second place, because thq
word canine may lead to an erroneous conception, by leading to a belief that this kind
of tooth belongs only to one kind of carnivorous animals, while they are stronger and
more distinct in the lion, the tyger, Sec.

The teeth differ essentially from the other bones, by the acute sensibility with which
they are endowed ; 2dly, by the nerves which may be traced into them, while they seem
to be wanting in every other part of the osseous system ; 3dly, by the mode of distribu-
tion of the blood-vessels : these penetrate into them at an aperture which is seen at the
extremity of their root, and they expand in the mucous membrane contained in the
tooth, and which forms the most essential part of the bone ; 4thly, by their not under-
going any change from exposure to the air, a property which they owe to the elmmel

82

Curved pincers. The grinders are principally employed in grinding sub-
stances previously divided by the laniary teeth, which tear them, or by in-
cisors, which, in meeting as the blades of scissars, fairly cut them through:
the latter, of which each jaw contains four, acting only on bodies which
present but a slight resistance, are placed at the extremity of the maxilary
lever. The grinders are brought nearer to the fulcrum, and it is on them
that the great stress of mastication rests. If we wish to crush a very hard
substance v, e instinctively place it between the last large grinders, and by
thus shortening considerably the lever, between the resistance and the ful-
crum, we improve on the lever of the third kind, which though most em-
ployed in the animal economy, acts the most unfavourably. Xhe laniary
teeth have very long fangs; which lying deeply buried in the alveolar pro-
cesses, give them a degree of firmness to enable them to act powerfully,
without danger of being loosened from their situation,

The enamel which covers the teeth, preserves the substance of the
bone exposed to the contact of the air, from the injurious effects, which
would not fail to result from direct exposure, and as enamel is much hard-
er than hone, it enables the teeth to break the hardest bodies without in-
jury. The concentrated acids soften this substance, and occasion a pain-
ful affection of the teeth. The sensibility possessed by these bones, is
seated in the mucous membrane which lines their inward cavity, through
which are distributed the vessels and nerves, which enter by openings at
their roots. This membrane is the seat of a great number of diseases,
to which the teeth are subject. The enamel, incessantly worn by repeat-
ed friction, grows and repairs its waste. The alveolar processes which
receive the fangs of the teeth, firmly embrace them, and all of them be-
ing exactly conical in form, every point of these small cavities, and not
merely their lower part at which the nerves and vessels enter, supports
the pressure which is applied to these bones. When from accidental
causes, or in the progress of age, the teeth are gone, their alveoli con-
tract*, then disappear; the gums, a reddish and dense membranous sub-
stance, which connects the teeth to the sockets, harden and become cal-
lous over their thinned edges. Old men who have lost all their teeth,
masticate but imperfectly, and' this circumstance is one of the causes of
their slow digestion, as the gastric juice acts with difficulty on food,
whose particles are not sufficiently divided.

X. Salivary Solution. The above mechanical trituration is not the only
change which the food undergoes in the mouth. Subjected to the action
of the organs of mastication, which overcome the force of cohesion of
its molecules, it is at the same time imbued with the saliva. This fluid
secreted by the glands placed in the vicinity of the mouth, is poured, in
considerable quantity, into that cavity during mastication.

The saliva is a transparent and viscous fluid, formed of about four parts
of water and one of albumen, in which are dissolved, phosphates of soda,
of lime, and of ammonia, as well as a small quantity of muriate of soda;

which covers them externally. It has been said, with justicef, that Nature, in sheath-
ing- the tooth with this covering, hatf imitated the process of tempering1, by means of
which, we harden the edge of steel or iron tools. — Author's Note.

* When the teeth of old persons are removed, or fall out, the alveoli are gradually,
and entirely absorbed ; this is what is meaiit by their contraction. — Godman.

f We should say very ricTiculouslv, as no analogy exists between the « processes." —

83

like all other albuminous fluids, it froths when agitated, by absorbing
oxygen, for which it appears to have a strong affinity. Its affinity for
oxygen is such, that one may oxydize gold and silver, by triturating
in saliva, thin leaves of those metals which are of such difficult oxy-
dizement.

The irritation occasioned by the presence or the desire of food, excites
the salivary glands; they swell and become so many centres of fluxion,
towards which the humours flow abundantly*. Bordeu first called the
attention of physiologists, to the great quantity of nerves and vessels re-
ceived by the parotid, maxillary and sublingual glands, from the carotid,
maxillary and lingual arteries, from the portio dura of the seventh pair of
nerves, from the lingual nerve of the fifth pair, which penetrate their sub-
stance, or pass over a portion of their surface. This great number of
vessels and nerves is proportioned to the quantity of saliva which is se-
creted, and this is estimated at about six ounces during the average time
of a meal. It flows in greater quantity, when the food that is used is
acrid and stimulating: it mixes with the mucus, copiously secreted with
the mucous, buccal, labial, palatine, and lingual glands, and with the se-
rous fluid, exhaled by the exhalent arteries of the mouth. The saliva
moistens, imbues, and dissolves the ball formed by the aliment, brings to-
gether its divided molecules, and produces on them the first change.
There can be no doubt, that the saliva mixing with the food by the mo-
tion of the jaws, absorbs oxygen, and unites to the alimentary substances,
a quantity of that gas fit to bring about the changes which they are ult>
mately destined to. undergof.

* The intimate sympathy or consent of action that exists between the functions of
the stomach and the salivary apparatus, by means of the nerves which chiefly preside
over the process of digestion and all the operations of secretion and nutrition, is strong-.
ly evinced by the following1 fact. An individual, in an attempt to commit suicide, divi-
ded the oesophagus to a considerable extent. During the attempts to preserve his exist-
cnce, food was conveyed into the stomach by means of a tube. As soon as the aliments
were received into this viscus, the salivary secretion became abundant, although the
process of mastication was not, of course, attempted. — Copland.

f The specific gravity of saliva is 1,038. It mixes with water only by trituration, has
a. strong affinity for ox\gen, absorbs it readily from the air, and gives it out again to
ether bodies. Whether it possesses any affinity for nitrogen, has not been shown ; nor
has the absorption of oxygen by this fluid, during t'.ie process of mastication, been suf-
ficiently attended to in our speculations respecting the pi-ocess of digestion. We can
hardly suppose that it takes up oxygen without a portion of nitrogen, or of common air.
If any quantity of the latter be mixed with it during the insalivation of the food, an evi-
dent source is disclosed from which nitrogen may be conveyed into the circulating1
fluids, in addition to that which is derived from the ordinary aliments.

The affinity which the saliva has for oxygen, and the readiness with which it gives
out this substance to other bodies, explains the reason why gold or silver triturated with
it is oxydized ; and why mercury soon disappears when triturated with saliva. Hence,
also, the reason why the application of saliva to sores is an useful remedy, and one to.
which the lower animals have constant recourse.

The constituents of saliva, according to BE RZ EMUS, are as follows :

Water, 992.9

Peculiar animal matter (precipitated by acet. plumbi) mucus of BOSTOCK, 2.9

Mucus* — albumen of BOSTOCK and TUOMPSOX, 1.4

Alkaline muriates, 1.7

Lactate of soda and animal matter, 0.9

Pure soda, : 0.2

1000.0

* The mucous or albuminous portion lias all the characters of albumen. On incine-

84

XI. The muscular parietes of the mouth are, during mastications, in
perpetual action. The tongue presses on the food, in every direction,
and brings it under the teeth ; the muscles of the cheek, especially the
buccinator, against which the food is pressed, force it back again under
the teeth, that it may be duly triturated. When the food has been suf-
ficiently divided, and imbued with saliva, the tip of the tongue is carried
to every part of the mouth, and the food is collected on its upper surface.
The food having been thus completely gathered together, the tongue
presses it against the roof of the mouth, and turning its tip upwards and
backwards, at the same time that its base is depressed, there is offered
to the food an inclined plane, over which the tongue presses it from be-
fore backwards, to make it clear the isthmus of the fauces, and to thrust
it into the oesophagus. In this course of the food along the pharynx,
and into the oesophagus, cosists deglutition, a function which is as-
sisted by the co-operation of several organs whose mechanism is rather
complicated.

XII. Deglutition. In the process of deglutition, the mouth closesby the
approximation of both jaws ; at the same time, the submaxillary muscles,
the digastrici, the genio-hyoidei^ the mylo-hyoidci^ Sec. elevate the larynx
and pharynx, by drawing down the os hyoides together with the lower
jaw, which is fixed by its levator muscles. The hyoglossus muscle, at
the same time that it elevates the os hyodies, depresses and carries, back-
wards the base of the tongue*. Then the epiglottis, situated between
these two parts, which are brought together, is pushed downwards and
backwards by the base of the tongue, which lays it over the opening of
the larynx. The alimentary mass, pressed between the palate and the
upper surface of the tongue, slides on the inclined plane formed by the
latter, and pressed by its tip, which bends back, clears the isthmus of
the fauces. The mucous substance which excludes from the surface of
amygdalae further facilitates the passage of the food. When the food
has thus drooped into the pharynx, the larynx, which had risen, and had
come forward, and which in that motion had drawn the pharynx along
with it, descends and falls backwards. This last organ stimulated by the

* In a memoir read before the French Institute, in 1813, M. Magendie related two
cases in which deglutition was performed without difficulty, although the epiglottis was
destroyed. He attributes the closure of the larynx to the action of the arytenoid mus-
cles, which are generally thought to be exclusively appropriated to the Voice. — God-

ration its ashes contain a considerable portion of phosphate of lime, although none of
that salt can be detected in it before incineration. It is this pecular substance which
adheres to the teeth, and gives origin to the tartar which surrounds them. This deposi-
tion, according to BERZELITJS, is composed of

Earthy phosphates, 79.0

Undecomposed mucus, 12.5

Peculiar salivary matter, 1,0

Animal matter soluble in mur. acid, 7.5

100

It cannot be doubted, that, like the other animal fluids, the constitution of this is lia-
ble to changes from disease. It is, however, a subject which has excited little atten-
tion among chemists and physiologists. BHrGsrAT.Ei.Lr found the saliva of a patient
labouring under an obstinate venereal disease, impregnated with oxalic acid.

The concretions which sometimes form in the salivary ducts, chiefly consist of phos-
phate of lime ia coagulated albumen. — Copland

85

pi-esence of the food, contracts, and would in part send it back in a re-
trograde direction, by the nasal fossae, if the velum palati, elevated by
the action of the levatorcs palati, stretched transversely by the tensores
palati, was not applied to their posterior apertures, and towards the
openings of the Eustachian tubes. Sometimes this obstacle is overcome,
and the food returns, in part by the nostrils. This happens, when during
the act of deglutition, we attempt either to laugh or speak. At such
times, the air, expelled from the lungs with a certain degree of force,
elevates the epiglottis, and meeting the alimentary mass, pushes it back
towards the nostrils through which it is to pass. The isthmus faucium
is closed against the return of the food into the mouth, by the swelling
of the base of the tongue, raised by the action of the constrictor fauciura,
and of the constrictor pharyngis superior, which are small muscles con-
tained in the thickness of the pillars of the velum.

The alimentary mass is directed towards the oesophagus, and is thrust
into that canal, by the peristaltic contractions of the pharynx, which may
be considered as the narrow7 part of a funnel-like tube. The. solid food
passes behind the uperture of the larynx, which is accurately covered
over by the epiglottis. The liquids flow along the sides of that opening,
along two channels easily distinguished. They are always of a more
difficult deglutition than the solids ; the molecules of a fluid have an in-
cessant tendency to separate from one another, and to prevent this sepa-
ration, the organs are obliged to use greater exertion, and to embrace
with more precision the substance that is swallowed. Thus, it is to be
observed, in those cases in which deglutition is prevented by some or-
ganic affection of the oesophagus, that the patients, though they have the
power of swallowing solid food, find it difficult to swallow a few drops of
a liquid, and are tortured with thirst, though they have still the power
of satisfying their hunger*.

The deglutition of air and of gaseous substances, is still more difficult,
than that of liquids, because these elastic fluids are much less coercible,
and it requires considerable practice, to transmit a mouthful of air- into
the stomach. M. Gosse, of Geneva, had acquired that power from re-
peated experience, and he made use of it to induce vomiting at pleasure,
and by the application of that faculty to the interests of science, he as-
certained the digestibility of the articles of food in most common use.

-The food descends into the oesophagus, propelled by the contractions
of that musculo-membranous duct, situated along the vertebral column,
from the pharynx to the stomach. Mucus is secreted, in considerable
quantity, by the membrane which lines the inner part of the oesophagus,
it sheathes the substances which pass along it, and renders their passage
more free. The longitudinal folds of their inner membrane, allow the
oesophagus to dilate ; nevertheless, when it is stretched beyond measure,
severe pain is experienced, occasioned, no doubt, by thedistention of the
nervous plexuses, formed by the nerves of the eighth pair, which embrace
the oesophagus, as they course along its sides — I purposely avoid speak-

* Hydrophobia, presents us with the most distressing examples of this kind The
very sight or sound of fluids produce dreadful spasms of the muscles of deglutition ;
sometimes, even speaking of fluids has the same effect. Dr. Fothergill's case, pub-
lished in the London Medical Observations and Inquiries, may be particularly referred
to, as the patient throughout had not the slightest suspicion of the nature cf his disease,
and the dread could not have beeai imaginary. — Godman.

86

ing of the weight of the food, as one of the causes which enable it to pass
along the oesophagus*. Although, in man as in quadrupeds, that weight
is no object to deglutition, it favours that function in so slight a degree,
that the diminution of muscular contractility at the approach of death,
is sufficient altogether to prevent it. The act of drinking is then attend-
ed with a noise of 'unfavourable omen. This noise consists in a gurgling
of the fluid which has a tendency to get into the larynx, whose opening
is not covered ever by the epiglottis; and if it be insisted upon, that the
patient shall swallow some pitsan, tfce deglutition of which is impractic-
able, it flows into the trachea, and the patient dies of suffocation.

XIII. Of the Jlbdoimn\. Before inquiring any farther into the pheno-
mena of digestion, let us shortly attend to the cavity which contains its
principal organs. The abdomen is almost entirely filled by the digestive
apparatus, of which the urinary passages form a part: its size, the struc-
ture of its parietes, are evidently adapted to the functions of that appara-
tus. The capacity of the abdomen, exceeds that of the other two great
cavities; its dimensions are not invariably fixed, as those of the skull,
whose size is determined by the extent of its osseous and inelastic pari-
etes. They are likewise more varying than those of the chest, because
the degree of dilatation, of which the latter is susceptible, is limited by
the extent of motion, of which the ribs and sternum are capable. The
abdomen, on the contrary, enlarges in a sort of indefinite mariner, by the
yielding of its soft and extensible parietes. In some cases of ascites, the
abdomen has been known to contain as much as eighty pints of liquid,
and yet death has not followed as a consequence of so enormous an accu-
mulation; while in consequence of the delicate texture of the brain, of
the exact fulness of the skull, and especially of the inflexibility of its pa-
rietes, the slightest effusions within that cavity are attended with so much
danger; while the collection of a few pints of fluid, within the chest, oc-
casions suffocation. This vast capacity of the abdomen, capable of being
easily increased, was required in a cavity whose viscera, for the most part
hollow, and admitting of dilatation, contain substances varying in quanti-
ty, and from which are disengaged gases occupying a considerable
space. What a difference is there not, in the capacity of the abdomen
of animals, according to the quality of the food on which they feed]

* A very curious instance of deglutition may be seen in the Java bat ; vespertilio vam-
pi/rns, ofLinnsus. The specimen of this animal, lately living- in the Philadelphia Mu-
seum, was continually pendent, by the hooks of one or both leg's. In this situation it
took food, which, when masticated, was forced, by a peculiar muscular movement, to
ascend perpendicularly to the stomach. — Godman.

•}- It is requisite, in physiology, as well as in medical practice, to have an artificial di-
vision of the abdominal cavity, in order to point out the exact and relative situations of
the viscera which it contains. With this view, it has been usually divided into three
regions, called the upper, middle, and under region : each of these is subdivided into three
others. The UPPKH region begins at the ensiform cartilage, and extends downwards to
about four inches from the umbilicus ; the middle of it is termed the epigastrium^ and
the t\vo lateral portions hypochondria, from their situation under the cartilages, of the.
false ribs.

The MIDDLE region occupies about four inches above and below the umbilicus. Its
middle portion is called the umbilieul, uncl its lateral parts the loins or lumbar regions.
The TI.VDER division of the abdominal cavity commences where the former one termi-
nates, or at a line drawn between the superior and anterior spinous process of the ossa
ilii, and forms, in the middle, the hupogaatrium, or bottom of the belly ; and at the sides,
the iliac regions. — Copland.

Compare the slender body of the tyger, of the leopard, and of all carni-
vorous animals, with the heavy mass of the elephant, of the ox, and of
all animals, that wholly or principally live on animal food. In the child,
who, for his growth and clevelopement, digests a considerable quantity of
food, the abdomen is much more capacious than in the adult, or the old
man. In the child, the ensiform cartilage is situated opposite to the
body of the eigth or ninth dorsal vertebra. In old men, it descends to
the tenth or even the eleventh, so that the capacity of the abdomen de-
creases with the want of food, and with the activity of digestion.

The internal organs of the body are incessantly called into action by
different causes, and excited to different motions*. The action of the ar-
terial system tends to raise the cerebral mass, and to impart to it mo-
tions of elevation and depression. The motion of the ribs brings about
the expansion and the compression of the pulmonary tissue; the heart,
which adheres to the diaphragm, drawn down by that muscle, when it
descends, strikes against, the parietes of the chest, every time its ventri-
cles contract. The abdominal viscera are not less agitated by the mo-
tions of respiration, they experience from the diaphragm and from the
abdominal muscles a perpetual action and re-action, by means of which,
the circulation of the fluids in their vessels is promoted, the course of
the food in the alimentary canal is accelerated, the activity of digestion
increased, and several excretions, as of the urine and fseces, performed.

XIV. Of Digestion in the Stomach^. The food which is taken into the
stomajch accumulates gradually within its cavity, and separates its pari-
etes, which are always in contact with each other when it is empty. The
stomach, in that mechanical distention by the food, yields without re-
acting. It is not, however, absolutely passive; its parietes apply them-
selves, by a general contraction, by a kind of tonic motion to the food
which lies within it, and to this action of the whole stomach, the ancients
gave the name of peristok\. As the stomach dilates, its great curvature
is thurst forward, the two folds of the omentum recede from each other,
receive it between them, and embrace its outer and dilated part. In
man, the principal use of this fold of the peritoneum, appears to be to
facilitate the dilatation of the stomach, which expands chiefly at its fore-
part, as may be observed by inflating it in a dead body. As this viscus
becomes distended with air, the two folds of the omentum apply them-
selves to its surface, and if this membrane is pierced with a pin, at the
distance of an inch from its great curvature, the pin is observed to get
nearer to this curvature; but the .upper portion of the omentum can
alone be employed in this use, and the whole of this membranous fold is
never entirely occupied by the stomach. Shall we say with Galen, that

* Before the skull is ossified, or after parts of the scullcap have been removed. When
the bone is entire, we have no reason to believe, that there is the slightest elevation or
depression of the brain. — Godman.

f See APPENDIX, Note K.

* In order to explain correctly the functions of the stomach either in their healthy
or disordered state, the conformation of the muscular coat requires to be pointed out.
This tunic is composed of three strata ; the^rrf, or the exterior, consists of longitudi-
nal fibres, proceeding from the oesophagus along the axis of the stomach and continued
to the duodenum ; the second, or middle stratum, which is the thickest, is composed of
fibres that have an oblique direction, and which, surrounding the stomach, decussate
one another ; the third, or interior stratum, consists entirely of circular fibres, which ex-
tend from one curvature of this viscus to the other Copland.

88

the omentum guards the intestines against cold, and preserves in them a
gentle warmth, necessary to digestion ; or shall we admit the opinion ot"
those who maintain, that it answers the purpose of a fluid, filling up
spaces, and lessening the effect of friction and pressure from the anterior
parietes of the abdomen ; or shall we assert with others, that the use of
the omentum is to allow the blood to flow into it, when the stomach, in
a state of contraction, is incapable of receiving it. May not the^blood
which flows so slowly in its long and slender vessels, acquire some olea-
ginous quality which renders it filter to supply the materials of bile*?

The stomach likewise stretches, though in a less distinct manner,
towards its lesser curvature, and the laminse of the gastro-hepatic
omentum are separated from each other, as those of the omentum
majus. ^ Such is the utility of the gastro-hepatic omentum, which may
be considered as a necessary result of the manner in which the peritoneum
is disposed in relation to the viscera of the abdomen. This membrane,
which extends from the stomach to the liver, so as to cover it, could not
fill the space which separates those organs, were it not for a kind of
membranous communication which connects them, ami in which are con-
tained the vessels and nerves, which, fro pi the lesser curvature, or the
posterior edge of the stomach, course towards the concave surface of the
liver. This gastro-hepatic epiploon, may besides, by the separation of
the t\Vo laminae of which it is formed, favour the dilation of the hepatic
vein, which is situated, as well as the vessels, the nerves, and the excre-
tory ducts of the liver, in the thickness of its right border.

The stomach has ever been considered as the principal organ of diges-
tion, yet its function in that process is but secondary and preparatory; it
is not in the stomach that the principal and most essential phenomenon
of digestion takes place, I mean the separation of the nutritive from the
excrementitious part of the food. The food, when received into the
stomach, is prepared for this separation which is soon to be performed,
it becomes fluid, and undergoes a material alteration ; it is converted into
a soft and homogeneous paste, known under the name of chyme. What
is the agent that brings about this change? or in other words, in what
does digestion in the stomach consist?

As it is frequently necessary to clear a spot on which one means to
build, we will bring forward and refute the hypotheses that have been
successively broached, to explain the mechanism of digestion. They
may be enumerated as follows : — concoction, fermentation, putrefaction,
trituration, and maceration of the food taken into the cavity of the
stomach.

XV. The first of these opinions was that of the ancients and of the fa-
ther of physic ; but, by the term concoction, Hippocrates did not mean
a phenomenon similar to that which takes place, when food is put into a
vessel, and exposed to the influence of heat. The temperature of the

* The omentum seems to lubricate the intestines by means of its adipose halitus,
and to aid in facilitating the continual movements of the intestines. It also appears to
assist in the reciprocal motion which takes place between the digestive tube and the
anterior abdominal parietes, especially in preventing the natural and increased action
of the latter, during respiration and muscular exertion, from impeding or injuring the
function of the former. It likewise obviates the adhesion of the intestines to the peri-
toneum during disease, and the consequent impediment to the operations of the
primse vise.— Copland.

89

stomach, which does not exceed that of the rest of the body, (32 degrees
of Reaumur's scale) would be insufficient. Cold-blooded animals digest
equally with the warm-blooded, and, as Vanhelmont observes, febrile
heat impairs, instead of increasing the powers of digestion. In the lan-
guage of the ancients, concoction means the alteration, the maturation,
the animalizationof alimentary substances, assimilated to our nature, by
the changes which they undergo in the cavity of the stomach. It is, how-
ever, a verified fact, that the natural heat of the stomach promotes and
facilitates those changes. The experiments of Spallanzani on artificial
digestion, show, that the gastric juice is not of more efficacy than plain
water, in softening and dissolving alimentary substances, when the heat
is below seven degrees (of Reaumur's scale;) that its activity, on the con-
trary, is greatly increased when the heat is ten, twenty, thirty, or forty
degrees above the freezing point. The digestion in the cold-blooded ani-
mals is, besides, slower than in the hot-blooded.

XVI. The abettors of the theory of fermentation admit that the food
taken into the stomach undergoes an inward and spontaneous motion, in
virtue of which it forms new combinations; and as the process of fer-
mentation is promoted, by adding, to the substance th-at is undergoing
that change, a certain quantity of the same that has already undergone
the process ; some have supposed that there continually exists in the
stomach a leaven, formed, according to Vanhelmont, by a subtle acid,
and consisting, in the opinion of others, of a small quantity of the food
that remains from the former digestion. But, independently of the cir-
cumstance that the stomach empties itself completely, and presents no
appearance of leaven, when examined a few hours after digestion, sub-
stances undergoing fermentation require to be kept perfectly at rest,
whereas the food is exposed to the oscillatory circulations and to the pe-
ristaltic contractions of the stomach, and this viscus is shaken by the
pulsations of the neighbouring arteries; it is besides kept in continual
motion by the act of respiration. In fermentation gases are either ab-
sorbed or extricated, neither of which circumstances takes place when
the stomach is not out of order.

It should, however, be stated, in support of the opinion that accounts
for digestion on the principle of fermentation, that we can derive nourish-
ment, only from substances capable of undergoing fermentation, and that
the substances which have undergone the panaryand saccharine fermen-
tation are more easily digested, and in less time. This imperceptible
fermentation, if it really take place, must bear a greater analogy to these
two last processes, to those which are called vinous and acetous fer-
mentation: but no one can differ from it more than the putrid fermen-
tation.

XVII. There have been physiologists, however, from the time ofPlis-
tonicus, the disciple of Pruxagoras, who maintain, that digestion is, in
fact, the consequence of putrefaction. But, not only is ammonia not dis-
engaged during that process, but our digestive organs have the power,
as will be seen presently, of retarding, or of suspending, the putrefaction
of the substances which are submitted to their action. In serpents,
which in consequence of the great power of dilatation of the oesophagus,
and from the power of holding asunder their jaws, both of which are
moveable nearly in an equal degree, frequently swallow larger animals
than themselves, and take several days to digest them; that part of the
animal which is exposed to the action of the stomach, is observed to be

M

90

perfectly fresh, and dissolved to a certain extent, while the part which
remains out, exhibits signs of incipient putrefaction, In fine, notwith-
standing the heat and moisture of the stomach, the food does not remain
in it long- enough, to allow putrefaction to come on, even though every
thing else should favour that process. Animals which have by chance
swallowed putrescent animal substances, either reject them by vomiting,
or, as Spallanzani has observed in some birds, deprive them of their
putridity.

XVIII. Tine system of fermentation was invented by the chemists;
that of trituration, by the mechanical philosophers, who compare the
changes which substances undergo in a mortar from the action of the
pestle, to the changes which the food undergoes in the stomach. But how
different is the triturating action of a pestle, which crushes a substance
softer than itself against a resisting surface, to the gentle and peristaltic
action of the fibres of the stomach, on the substances which it contains.
Trituration, which is a mechanical effect, does not alter the nature of the
substance exposed to its action; but the food is decomposed, and no
longer the same substance, after it has remained some time in the sto-
mach. As this evidently absurd hypothesis has long been heid in high
estimation, it will not be improper to spend a little time in the refutation
of the proofs which are adduced in its support.

The manner in which digestion is brought about in birds, whose sto-
mach is muscular, and especially in the gallinaceous fowls, is the most
specious argument adduced by the abettors of mechanical digestion.
Those granivorous birds all have a double stomach, the first is culled the
crop, its sides are thin and almost entirely membranous; a fluid is abun-
dantly effused on its inner surface, the seeds on which they feed get
softened, and undergo a kind of preliminary maceration in the crop, after
which they are more easily ground by the gizzard, which is a truly mus-
cular stomach, that fulfils the office of organs of mastication, almost en-
tirely deficient in that class of animals. The gizzard acts so powerfully,
that it crushes the solid substances exposed to its action, reduces into
dust balls of glass and crystal, flattens tubes of tin, breaks pieces of me-
tal, and what is much more extraordinary, breaks with impunity the
points of the sharpest needles and lancets. Its internal partis lined with
a thick semicartilaginous membrane, incrusted with a number of small
stones and gravel, taken in with the food of those birds. The turkey cock
is, of all other fowls, that in which this structure is most apparent ; be-
sides the small pebbles which line its inner membrane, its cavity contains,
almost in all cases, a number of them. The rubbing together of these
hard substances, exposed along with the seeds among which they are
mixed, to the action of the stomach, may assist in breaking them down.
The pieces of iron and the pebbles which the ostrich swallows, some of
which Valisnieri met with' in the stomach of that bird, are destined to
the same use. But this mechanical division which the gizzard performs
in the absence of organs of mastication, does not constitute digestion; the
food softened and divided by the action of the crop and of the gizzard,
passes into the duodenum, and exposed in that intestine to the action of
the biliary juices, undergoes within it the changes most essential to the
act of digestion.

The singular structure of the lobster's stomach is not more favourable
to the hypothesis of trituration. In that crustaceous animal, the stomach
is furnished with a real mandibular apparatus, destined to break down

91

the food. There are found in it, besides, at certain times of the year,
two roundish concretions, on each side, under its internal membrane.
These concretions, improperly termed crabs' eyes, consist of carbonate
of lime joined to a small quantity of gelatinous animal matter; they dis-
appear, when, after the annual shedding of the shell, the external cover-
ing, at first membranous, becomes solid from the deposition of the calca-
reous matter of which they are formed.

The very great difference between the stomach of these animals and
that of man, ought to have precluded every idea of comparing them toge-
ther. Spallanzani has justly observed, that in regard to the muscular
power of the parietes of the stomach, animals might be divided into three
classes, the most numerous of which consists of those creatures, whose
stomach is almost entirely membranous, and furnished with a muscular
coat of very little thickness. In thi§ class are contained, man, quadru-
peds, birds of prey, reptiles, and fishes. Notwithstanding the weakness
of that muscular coat, Pitcairn, by a misapplied calculation, has estimated
its power at 12,951 pounds; he reckons at 248,335 pounds, that of the
diaphragm and of the abdominal muscles which act on the stomach, and
compress it in the alternate motions of respiration. What does so exag-
gerated a calculation prove, except, as Garat observes, that this vain
show of axioms, definitions, scholia, and corollaries, with which works
not belonging to mathematics have been disfigured, have served only to
protect vague, confused, and false notions, under the cover of imposing
and respected forms. One need only introduce one's hand into the abdo-
men of a living animal, or a finger into a wound of the stomach, to as-
certain that the force of that viscus on its contents, does not exceed a
few ounces.

XIX. The learned and indefatigable Haller thought, that the food was
merely softened and diluted by the gastric juice. This maceration was,
in his opinion, promoted and accelerated by the warmth of the part, by
the incipient putrefaction, by the gentle bui continual motions which the
alimentary substance undergoes. Maceration, in time, overcomes the
force of cohesion of the most solid substances ; but by dilution it never
changes their nature. — Haller rested on the experiments of Albinus,
on the conversion of membranous tissues into mucilage, by protracted
maceration.

In ruminating animals, the cavity of the stomach is divided into four
parts, which open into one another, and of which the three first commu-
nicate with the oesophagus. When the grass, after imperfect trituratiou
by the organs of mastication, whose power is inconsiderable, has reached
the paunch, which is the first and largest of the four stomachs, it under-
goes a real maceration, together with an incipient acid fermentation. —
The contractions of the stomach propel the food, in small quantities at a
time, into the bonnet, which is smaller and more muscular than the
paunch; it coils on itself, covers with mucus the already softened food,
then forms it into a ball, which rises into the mouth, by a truly antiperi-
staltic motion of the oesophagus. The alimentary bolus, after having
been chewed over again by the animal, which seems to enjoy that pro-
cess, descends along the oesophagus into the third stomach, called the
manyplus, on account of the large and numerous folds of its inner mem-
brane. From this cavity the food enters into the abomasum, in which
the stomachic digestion is completed. Such is the mechanism of rumi-
nation, a function peculiar to animals that have four stomachs: they do

not, however, ruminate at all periods of their life. The sucking lamb
does not ruminate : the half digested milk does not pass along the paunch
or the bonnet, which are useless, but at once descends into the third
stomach*. Some men have been capable of a kind of rumination; the
alimentary ball, after descending into the stomach, shortly alter rose in-
to the mouth, to be there chewed a second time, and to be anew imbued
with saliva. Conrad Peyer has made this morbid phenomenon the sub-
ject of a dissertation, entitled Mericologia, sine fa t&r-inantibm\.

This fourfold division of the stomach, so favourable to Mailer's theory,
is observed only in ruminating' animals. But though animal* are in ge-
neral monogastric, as map? that is, provided with only one stomach, this
viscus offers a number of varieties, the most remarkable of which refer
to the relative facility which the food meets, in remaining within its ca-
vity. The insertion of the oesophagus is nearer to its left extremity, and
the great fundus of that viscus is smaller, as animals feed more exclusive-
ly on flesh, which is a substance of remarkably easy decomposition, and
not requiring for its digestion a long stay in the stomach. In herbivo-
rous quadrupeds, which do not ruminate, this great fundus forms nearly
one half, sometimes even the greater part of the stomach, as the oesopha-
gus enters into it very near the pylorus. In some, as in the hog, the sto-
mach is divided into two parts by a circular contraction. The food
which is received into the great fundus of the stomach, may remain
longer in that viscus, as this part of its cavity lies out of the course of
the aliment.

XX. Of the Gastric Juice. Of all the organs, the stomach probably re-
ceives, in proportion to its bulk, the greatest number of blood-vessels j
in its membrane-muscular parietes, which are little more than the twelfth
part of an inch in thickness, there is distributed the coronary artery of
the stomach, entirely destined to that organ , the pyloric, the right
gastro-epiploic, given off by the hepatic artery. The greater part of the
blood, therefore, which passes from the aorta to the. cseliac artery goes to
the stomach, for thougr11 ot tne arteries into which that trunk is divided,
the coronary of tne stomach is the least, the arteries of the liver and
spleen send to the stomach several pretty considerable blanches, before
entering the viscera to which they are more particularly allotted. One
need only observe the great disproportion between the stomach and the
quantity of blood which it receives, to conclude, that this fluid is not
merely subservient to its nutrition, but is destined to furnish the materi-
als of some secretion.

The secretion in question, is that of the gastric juice, which is most
abundantly supplied by arterial exhalation, from the internal surface of
the stomach ; it is most active at the instant when the food received \
within its cavity, excites irritation, transforms it into a centre of fluxion^
towards which the fluids flow from all directions. The state of fulness
of the stomach, favours the afflux of the fluids into the vessels, as, in con-
sequence of the extension of its parietes previously collapsed, the vessels
are no longer bent and creased. The arteries of the stomach, of the
spleen and liver, arising from a common trunk, it may be easily under-

* Seethe Journal of Foreign Medicine published in Philadelphia* No. 4, p. 472".. —
Godman.
| See APPENDIX, Note K.

stood how, \frhen the stomach is empty, little biood enters into it, in that
state of contraction ; how at the same time, the spleen which is less com-
pressed, and the liver, must receive a larger supply of blood, and again a
smaller quantity, when the stomach is full.

The gastric juice, the result of arterial exhalation, mixes with the mu-
cus poured out by the mucous follicles of the internal membrane of the
stomach. This mixture renders it viscous and ropy, like the saliva, to
which, in man, the gastric juice bears a-great analogy. It is very difficult
to obtain it pure, so as to analyze it, and even if by long fasting, the sto-
mach should be deprived of the alimentary residue, which might affect its
purity, (5ne could not prevent its being mixed with a certain quantity of
liquid bile, which always flows back through the pyloric orifice, turns
yellow the inner surface of the stomach, in the neighbourhood of that
orifice, and even imparts a certain degree of bitterness to the gastric
juice. The passage of the bile from the duodenum into the stomach, can-
not be looked upon as morbid; it occurs in the most perfect health,
which has led to a well founded opinion, that a small quantity of the bili-
ary fluid is a useful stimulus to the stomach. This opinion is confirmed
by an observation of Vesalius, who relates, that he found the ductus
communis choledochus, opening into the stomach, in the body of a con-
vict noted for his voracious appetite. It is further confirmed by what is.
observed in birds of prey, in the pike, Sec. who digest easily and with
great rapidity, because the termination into the duodenum of the ductus
communis choledochus, being very near to the pylorus, the biie easily
ascends into the stomach, and is always found there in considerable
quantity.

To obtain some of this gastric juice, it is necessary, either to open a
living animal under the influence of hunger, or to oblige a night bird of
prey, as an owl, to swallow small spunges fastened to a long thrend.
When the spunge has remained for a s >ort time in the stomach, it is
withdrawn soaked with gastric juice, of which the secretion has been pro-
moted by its presence in the stomach.

The gastric juice, in its natural state, is neither acid nor alkaline : it
does not turn red or green, vegetable blue colours*. Its most remarka-
ble quality is, its singularly powerful solvent faculty, the hardest bones
cannot withstand its action; it acts on those on which the dog feeds; it
combines with all their organized and gelatinous parts, reduced them to
a calcareous residue, forming those excrementitious substances so ab-
surdly called album graseujn, by the older chemists. The solvent energy
of the gastric juice, is in inverse ratio of the muscular strength of the

* There is some difference of opinion on this point. Carminati declares that in car-
nivorous animals the gastric fluid is add, that in phytivorous it is alkaline, and that in
those which live indiscriminately on animal and vegetable food, it is neither acid nor
alkaline. By BrugnatelU it is said that, in all animals, it is uniformly acid. That the
gastric hquor is occasionally acid in the human species, cannot be denied. It has in-
deed been found so both by Reaumur and Hunter, and in subjects where there was no
reason to presume it had become vitiated by a disordered condition of the stomach.

We are inclined to believe that the gastric fluid has pretty nearly the same proper-
ties in all animals. In support of this conclusion we may appeal to" the fact which has
been verified by repeated experiments, that both carnivorous and phytivorous animals
digest and thrive well on an exchange of food, the one being- made to feed exclusively
on vegetable, and the other on animal matter. Vide Experiments of J. Hunter and
Spallanzam. — Chapman.

94

parietes of the stomach, and in those animals in which the parietes of
that viscus arc very thin, and almost entirely membranous, it has most
power and activity. In the numerous class of zoophytes, it alone suffices
to effect decomposition of the food, always more prompt, when accom-
panied by warmth of the atmosphere, as \vas observed by du Trembly, in
the polypi, which in summer, dissolve in twelve hours, what in colder
weather it would take three days to digest. In the actinia, in the holo-
thuda, the gastric juice destroys even the shells of the muscles which
they swallow. Are we not all acquainted with the peculiar flavour of
oysters, how much they tend to whet the appetite ? this sensation de-
pends less on the salt water contained in the shell, than on the' gastric
juice which acts on the tongue, which softens its tissue, and quickens its
sensibility*. This mucous substance, when received into the stomach,
promotes the digestion of the food which is afterwards taken into it, for
the oyster itself is very little nutritious, and is used rather as a condi-
ment, than as affording nourishment.

The gastric juice not only pervades and dissolves the food received in-
to the stomach, but it unites and intimately combines with it, completely
alters its nature, and changes its composition. The gastric juice acts, in
a manner peculiar to itself, on the food exposed to its action, and far from
inducing a beginning of putrefaction, suspends on the contrary, and cor-
rects putrescency. This antiseptic quality of the gastric juice, suggest-
ed the practice of moistening ulcers with it to accelerate their cure, and
the experiments made at Geneva and in Italy, have, it is said, been fully
successful. I have made similar experiments with saliva, which, there
is every reason to consider, is very similar to the gastric juice, and I have
seen old and foul ulcers assume a better appearance, the granulations be-
come healthy, and the affection rapidly advance towards a cure, from the
use of that irritating fluid. I had under my care an obstinate sore on the
inner ankle of the left leg of an adult; notwithstanding the external ap-
plication of powdered bark, and of compresses soaked in the most deter-
gent fluids, this sore was improving very slowly, when I bethought my-
self of moistening it every morning with my saliva, the secretion of which
was increased by the hideous aspect of the sore. From that time, the
patient evidently mended, and his wound contracting daily, at last became
completely cicatrized.

However powerful the efficacy of the gastric juice, to dissolve the ali-
mentary substances, it does not direct against the coats of the stomach
its active solvent faculty. These parietes endowed with life, powerfully
resist solution. The lumbrici so tender and delicate, for the same rea-
son, can exist within it, without being in the least affected by it, and such
is this power of vital resistance, that the polypus rejects unhurt its arms,
when it happens to swallow them among its foodf. But when the stomach
and the other organs have lost their vitality, its parietes yield to the sol-
vent power of the juices which it may contain, they become softened, and

* The whole of this sentence, and the subsequent one, is inapplicable. When we
swallow raw oysters, we do not wait for them to soften tlie tongue ,• and in this country,
at least, daily experience teaches that they are extremely nutritious. — Godman.

•j- It had been thought, that no animal could live on the flesh of his own kind, and
this circumstance was explained on the same principle ; but to refute it, we need only
quote the instance of cannibals, and of several tribes of carniverous animals, who, in the
absence of other prey, devour one another. — Author's Note.

95

even in part destroyed, if we may believe Hunter, who found its inner
membrane destroyed in several points in the body of a criminal, \vhofor
some time before his execution, had been prevailed upon, in considera-
tion of a sum of money, to abstain from food*.

The gastric juice is capable, even after death, of dissolving food intro-
duced into the stomach, by a wound made into it, provided the animal
still preserves some degree of animal heat. It acts on vegetable and ani-
mal substances triturated and put into a small vessel, such as those under
which Spallanzani, in his experiments on artificial digestion, kept up a
moderate heat. Let us not, however, consider as the same, this solution

.at The following case of solution of the stomach after death came under the observa-
tion of Professor Haviland. The subject was a young- man whose body was opened
twelve hours after death, and the stomach, on being examined after its removal from
the body, presented the following appearances: — The mucous membrane seemed more
red and vascular than usual throughout its whole extent, and here and 'there were
small spots of what seemed to be extravasated blood, lying beneath the mucous coat,
as they could not be washed oft, nor removed by the edge of the scalpel. There were
two holes in the stomach ; the larger very near to the cardiac end of the small curva-
ture, and on the posterior surface ; this was more than an inch in length, and about
half an inch in breadth The other, not far from the former, and likewise upon the
posterior surface, was about the size of a sixpence. The edges of these holes were
smooth, well defined, and slightly elevated. The coats of the stomach were thin in
many other spots, and in one part nothing was left but the peritoneum, the mucous
and muscular coats being entirely destroyed There was a hole in the diaphragm
through the muscular portion, where it is of considerable thickness, large enough to
admit the end of the finger. There was no appearance of ulceration or of pus adher-
ing to the edges of this perforation of the diaphragm. Dr. Haviland concludes, that,
owing to the activity of the solvent power of the gastric juice, it sometimes not only
corrodes the parietesof the stomach, but even the thick muscle of the diaphragm, and

that within the space of twelve hours after death, as was exemplified in this case.

Transactions of the Cambridge Philosophical Society , Vol. I. Pan II. 1S22.

Hunter's view of this subject has been disputed, to the present day, by several emi-
nent pathologists ; but Dr. Philip's observations are qualified to prove it in a very satis-
factory manner to those who yet required uriore convincing arguments. On opening
the abdomen of rabbits which had been killed immediately after having eaten, and
which were allowed to lie undisturbed for some time before the examination, he has
found "the great end of the stomach soft, eaten through, sometimes altogether con-
sumed, the food being only covered by the peritoneum, or lying quite bare for the
space of an inch and a half in diameter; and part of the contiguous intestines, In the
last case, also consumed, while the cabbage, \\ hich the animal had just taken, lay in
the centre of the stomach unchanged, if we except the alteration which had taken
place in the external parts of the muss it had formed, in consequence of imbibing gas-
tric fluid from the half-digested food in contact with it."

The following are Dr. Philip's observations :— « We sometimes found the great end
of the stomach dissolved within an hour and a half after death. It was more frequently
found so when the animal bad lam dead .for many hours. This effect does not always
ensue, however long it has kin dead. It seems only to take place when there happens
to be a greater than usual supply of gastric fluid ; for we always observed it most apt
to happen when the animal had eaten voraciously.

« Why it should take place without the food being digested, is evident from what
has been said. Soon after death, the motions of the stomach, which are constantly
carrying on towards the pylorus the most digested food, cease. Thus, the food which
lies next to the surface of the stomach, becoming fullv saturated with gastric fluic
neutralizes no more, and no new food being presented to it, it necessarilf acts on the
tomach itself, now deprived of life, and, on this account, as Mr. Hunter justly observes
equally subject to its action with other dead an-mal matter. It is remarkable that ti'e
gastric fluid of the rabbit, which in its natural state refuses animal food, should so com
pletely digest its own stomach as not to leave a trace of the parts acted on T never

endi in ou'erparts> "* intemal

96

of the food in the gastric juice, out of the stomach, and that which oc-
curs in digestion within the organ. Every thing tends to show, that the
stomach ought not to be considered as a chemical vessel, in which there
takes place a mixture giving rise to new combinations. The tying the
nerves of the eighth pair, the use of narcotic and of opium, intense
thought, every powerful affection of the mind, trouble or even gaiety,
entirely suspend digestion in the stomach, which cannot take place inde-
pendently of nervous influence. Yet this nervous influence may possi-
bly not concur directly, and of itself, to stomachic digestion; it is perhaps
merely relative to the secretion of the gastric juice, which the ligature of
the nerves, the action of narcotics or of other substances may impede,
alter, or even completely suspend.

It is now very generally admitted, that digestion in the stomach c£n-
sists in the solution of the Ibod in the gastric juice. This powerful sol-
vent penetrates, in every direction, the alimentary mass, removes from
one another, or divides its molecules, combines with it, alters its inward
composition, and imparts to it qualities very different from those which
it possessed before the mixture. If, in fact a mouthful of wine or of
food is. rejected, a few minutes after being swallowed, the smell, the fla-
vour, all the sensible and chemical qualities of such substances, are so
completely altered, that they can scarcely be recognized; the vinous
substances turned, to a certain degree, sour, are no longer capable of the
acetous fermentation. The energy of the solvent power of the gastric
juice, perhaps over-rated by some physiologists, is sufficient to dissolve
and reduce into a pulp, the hardest bones on which some animals feed.
It is highly probable, that its chemical composition varies at different
times; that it is acid, alkaline or saponaceous, according to the nature of
the food. Although the gastric juice be the most powerful agent of di-
gestion, its solvent power requires to be aided by several secondary
causes, as warmth, which seems to increase, and, in a manner, to concen-
trate itself in the epigastric region as long as the stoti'.ach is engaged
in digestion ; a sort of inward fermentation which cannot be, strictly
speaking, compared to the decomposition which substances, subject to-
putrefaction and acescency undergo. The gentle and peristaltic action
of the muscular fibres of the stomach, which press in every direction, on
the alimentary substance, performs on it a slight trituration, while the
moisture of the stomach softens and macerates the food, before it is dis-
solved ; one might therefore say, that the process of digestion is at once
chemical, mechanical, and vital ; in that case, the authors of the theories
that have been broached, have been wrong, only in ascribing to one cause,
such as heat, fermentation, putrefaction, trituration, maceration, and the
action of the gastric juice, a process which is the result of a concurrence
of these causes united*.

The food remains in the stomach, during a longer or shorter space of

* Dr. A. Wilson Philip has lately made some experiments to prove, that when the
nerves going- to the stomach are divided, the digestion of the food may, notwithstand-
ing, be produced, by passing* a current of the galvanic fluid, so as to form a communi-
cation between the ends of the cut nerves. We are not, however, so willing to draw
the inference, that the nervous power, or influence, is identical with the galvanic agent.
The nerves, in his experiments, were not all divided ; and we can readily conceive how
so powerful a stimulus as galvanism, might excite the remaining nerves sufficiently to
produce the effect reported by Dr. Wilson. —Godman.

97

time, according as by its nature, it yields more or less readily to the
changes which it has to undergo. Gosse of Geneva, ascertained, by ex-
periments performed on himself, that the animal and vegetable fibre, con-
crete albumen, white and tendinous parts, paste containing fat or butter,
substances which have either not undergone fermentation, or which do
not readily undergo that process, remain longer in the stomach, offer
more resistance to the gastric juice, than the gelatinous parts of animals
or vegetables, fermented bread, Sec.; that the latter required but an hour
for their complete solution, while the former were scarcely dissolved, at
the end of several hours.

XXI. The following case throws, I think, some light on the mechan-
ism and importance of the action of the stomach in digestion. The pa-
tient was a woman whom I had frequent opportunities of examining at
the " hopital de la charite," at Paris, in the clinical wards of Professor
Corvisart, in which she died on the 9tn Nov. of the year 1807, after six
months' stay in the hospital*

A fistulous opening, of an oval form, an inch and a half in length, and
upwards of an inch in breadth, situated at the lower part of the chest, at
the upper and left side of the epigastric region, afforded an opportunity
of viewing the inner part of the stomach, which, when empty of food,
appeared of a vermilion colour, was covered with mucus, its surface
wrinkled over with folds about half an inch deep, and enabled one to dis-
tinguish the vermicular undulations of these folds, and of all the parts
which were in sight. The patient, who was then forty-seven years of
age, had this fistula since she was in her thirty-eighth year. Eigh-
teen years before, she had fallen on the threshold of a door, the blow
had struck against her epigastric region. The place remained affected
with pain, and she became incapable of walking or of sitting, otherwise
than bent forward and to the left side. At the end of this long interval
a phlegmonous and oblong tumour appeared on the injured spot : during
the nausea and vomiting which came afterwards, the tumour broke, and
there escaped at the wound, which was left by this rupture, two pints of
a fluid which the patient had just swallowed to obtain relief. From that
time, the fistula, which at first, would scarcely have admitted the tip of
the little finger, increased daily j at first it allowed only the fluids to pass,
but, on the eighth day, the solid food came away freely, and continued to
do so till she died. When admitted into the hospital, she ate as much as
three women of her age, she voided about a pint of urine, and went to
stool only once in three days. Her faeces were yellowish, dry, rounded,
and weighed more than a pound. Her pulse was very feeble and ex-
tremely slow, its pulsation scarcely exceeding forty-five or forty-six beats
in a minute. Three or four hours after a meal, an irresistible desire
obliged her to take off the lint and compresses with which she covered
the fistulous opening, and to give vent to the food which her stomach
might happen to contain; it came out rapidly, and there escaped at the
same time, and with a noise, a certain quantity of gases. The food thus
evacuated, exhaled an insipid smell, was neither acid nor alkaline, for, the
chymous and greyish coloured pulp into which they were reduced, when
suspended in a certain quantity of distilled water, did not affect vegetable
blues. The digestion of the food was far from being always complete ;
sometimes, however, the smell of wine could not be recognized, and
the bread formed a viscid, thick, and soft substance, similar to fibrine

N

98

newly precipitated by the acetous acid, and it floated in a tenacious liquid
of the colour of common broth*.

It follows, from the experiments performed at the Ecole de Medicine,
on these half digested substances, and on the same before their admission
into the stomach, that the changes which they undergo, consist in the in-
crease of gelatine, in the formation of a substance which has the appear-
ance of fibrine, without having all its qualities, in a greater proportion of
muriate and phosphate of soda, as well as of phosphate of lime.

This patient was unable to sleep, till she had emptied her stomach,
which she cleared by swallowing a pint of infusion of chamomile. In the
morning, there was seen in the empty stomach a small quantity of a ropy-
frothy fluid, like saliva. It did not turn vegetable blues to a green or
red colour, was not homogeneous, but exhibited particles, of some de-
gree of consistence, among the more fluid parts, and even albuminous
flakes completely opaque. The experiments performed on this fluid,
showed that it bore a considerable analogy*4o saliva, which, however, is
rather more liable to putrefaction.

The vermicular motion by which the stomach cleared itself of its con-
tents, took place in two different, but not in opposite directions, the one
pressing the food towards the fistulous opening, the other towards the
pylorus, through which the smaller quantity was allowed to pass.

On opening the body, it was found, that the fistula extended from the
cartilage of the seventh left rib, as high as the osseous termination of the
sixth ; its edges were rounded, and from three to four lines in thickness;
they were covered with a thin moist skin, of a red colour, and similar to
that of the lips. The peritoneal coat of the stomach adhered so firmly
to the peritoneum lining the fore part of the abdomen, around the open-
ing, that the line of adhesion would notbe observed. The opening was

* Dr. Prout has made several experiments in order to ascertain the chemical com-
position of the chyme, from which he obtained the following results : — •

No. 1. Chyme of a dog fed on vegetable food. Composed of a semi-fluid, opake, yel-
lowish white part, containing another portion of similar colour, but of firmer consist-
ence mixed with it. Spec. grav. 1.056. It showed no traces of a free acid, or alkali,
but coagulated milk completely, when assisted by a gentle heat.

No. 3. Chyme of a dog1 fed on animal food. This was more thick and viscid than
No. 1. and its colour was more inclining; to red. Spec. Grav. 1.022. It showed no
traces of a free acid, or alkali, nor did it coagulate milk, even when assisted by the
most favourable circumstances.

On being subjected to analysis, these two specimen's of chyme were found to con-
sist of —

A. Water, .....

1. Chyme from
vegetable food.
86-5

2. Chyme from
animal food.
80«

B. Gastric principle, or mucus united with aiimen-
tary matters, and apparently constituting the
chyme, properly so called, mixed with excre-
mentitious matter, ...... . .'

I

6 •

15-8

C. Albuminous matter, chiefly fibrine,

1-3

1-6

1*7

E. Vegetable gluten,

5-

.7

.7

G. Insoluble residuum, ,

.2

•5

100-

100-

F. The saline matters were obtained by incineration, and consisted chiefly of the mu-
riates, sulphates, and phosphates.— Copland.

99

in the anterior part of the stomach, at the unienoi' the two-thirds on the
left side, with the third on the right of that viscus ; that is, about eight
fingers' breadth from its greater extremity, and only four from the py-
lorus. It extended from the greater to the lesser curvature, In other
respects, it was the only organic affection of that vkcus.

It should be stated, that for several years, the patient had been thin
and emaciated, and had led a languid life, which was terminated by a col-
liquative diarrhoea. She seemed to be supported only by the small quan-
tity of food which passed through the pylorus, into the duodenum, where
it received the influence of the bile, whose action on the chyme, is, as
we shall presently state, absolutely essential to the separation of the nu-
tritious parts*. Not that there was any thing to prevent the absorbents of
the stomach from taking up a certain quantity of nutritious particles, but
that small quantity of food in an imperfect condition, was of very little
service in imparting nourishment, and, in that respect, she was in similar
circumstances to patients who are affected with obstruction of the pylo-
rus, and reject the greater part of their food, when, digestion being over,
this contracted opening can no longer allow any food to passf.

XXII. While the alimentary solution is going on, the two openings of
the stomach remain perfectly closed ; no gas disengaged from the food,
escapes along the oesophagus, except when digestion is imperfect. A
slight shivering is felt, the pulse becomes quicker, and more contracted,
the vital power seems to forsake the other organs, to concentrate itself
on that which is the seat of the digestive process. The parietes of the
stomach are soon called into action ; its circular fibres contract in differ-
ent points ; these peristaltic oscillations, at first irregular and uncertain,
acquire more regularity, and act from above downwards, and from the
left to the right, that is to say, from the cardiac to the pyloric orifice. Be-
sides, its longitudinal fibres shorten it, in the fcv***imr6f its greatest dia-
meter, and bring nearer to each other it3 two orifices. In these different
motions, the stomach rises over che pylorus, so that the angle which it
forms with the duoden«ru> almost entirely ceases, and this facilitates the
escape of the food. It has been observed, that during sleep, digestion
takes place much more readily, when we lie on the right, than on the
left side, and this circumstance has been ascribed to the compression of
the liver on the stomach. It is much more likely to depend on the cir-
cumstance, that when we He on the right side, the passage of the food is
facilitated by its own weight, the natural obliquity of the stomach, from

* This is very satisfactorily demonstrated by the experiments of B. C. Brodie, F. R.
S. He applied ligature's on the common gall duct (choledochus communis) and found
that the change of the materials taken into the stomach was affected as usual. Chyme
was formed. But when the chyme passed into the intestines, there was no chyle pro-
duced, nor could any trace of it be found in the intestines or lacteal*. As the mass ap-
proached the larger intestines, is became thicker, by the absorption of the watery parts,
but without any other change.

As the results obtained in Mr. Brodie's experiments were uniformly the same, we be-
lieve him justified in concluding, " that the office of the bile is to change the nutritious
part of the chyme into chyle ; and to separate from it the excrementitious matter." See
Phil, and Med. Jour. No. 12, p. 400.— Godman.

f Cases, in many respects similar to the above, are recorded by different writers. —
Haller, in his" Chirurgical Dissertations," has the history of a woman with an aperture
in her stomach, through which she was nourished for twenty-seven years. For other in-
stances of tistulous openings in this viscus, consult the " Irish Transactions," and "Me-
dical Facts and Observations. " — Chapman.

100

left to right, being increased by the changes attending the prts§Hce of the
food.

XXIII. On the Uses of the Pylorus. The pyloric orifice is furnished
with a muscular ring, covered over by a fold of the mucous membrane
of the stomach. This kind of sphincter keeps it perfectly closed, while
digestion is going on in the stomach, and will not allow a free passage to
the food which has not yet undergone a sufficient change. The pylorus,
which is endowed with a peculiar and delicate sensibility, may be con-
sidered as a vigilant guard, which prevents any thing from passing into
the intestinal canal, till it has undergone the necessary changes. Seve-
ral authors quoted by Haller, have, very justly, observed, that the ali-
mentary substances do not leave the stomach in the same order that they
were received into it, but that they are evacuated according to their de-
grees of digestibility.

One may say, that there really takes place in the stomach, a sorting of
the different substances which it contains. Those that are most readily
dissolved, get near to the pylorus, which admits them, rejecting those
which, not yet sufficiently digested, cannot produce on it the necessary
affection. To this delicacy of tact, which I ascribe to the pylorus, will
be objected, perhaps, the passage it allows to pieces of money and other
foreign indigestible substances. But these bodies, which have always
lain some time in the stomach, before they make their way into the in-
testines, repeatedly attempt the orifice of the pylorus, and pass through,
only when they have at last accustomed it to their contact. The gastric
system is under the laws of a secretory gland; and as the roots of the
excretory ducts, being endued with a sort of elective sensibility, will not
receive the secreted fluid, until it has undergone the necessary prepara-
tion in the glandular parenchyma, in the same manner, the pylorus ad-
mits aliments, and givc» them passage into the intestines, which may be
regarded as the excretory ducia of the stomach, only when they have
been sufficiently elaborated by the action uf this organ.

XXIV. As the stomach empties itself, the spaatn of the skin goes off;
the shivering is followed by a gentle warmth; the pulse increases in ful-
ness and frequency; the insensible perspiration is augmented. Diges-
tion brings on, therefore, a general action analogous to a febrile paroxysm;
and this fever of digestion, noticed already by the ancients, is particu-
larly observable in women of great sensibility. Nothing positive can
be said on the duration of stomachic digestion; food passes sooner or
slower from the stomach, according as its nature is such as to resist, more
or less, the actions which tend to dissolve it ; according too to the
strength and vigour of the stomach at the time, and to the activity of the
gastric juices. Yet we may state from three to four hours as the mean
time of their remaining there. It is of consequence to know the time re-
quired for digestion in the stomach, that we may not disturb it by baths,
bleedings, &c. which would call off towards other organs, those powers
which ought, at that time, to be concentrated upon the stomach.

If, as is indisputable, the stomach carries with it, into its action, all the
other organs of the economy; if it summons to its aid, so to say, the
whole system of the vital powers; if this sort of derivation is the more
conspicuous, as the organization is more delicate, the sensibility more
lively, the susceptibility greater, the importance is apparent of enforcing
a strict diet in acute diseases, and in all cases where Nature is engaged
in an organic operation, which a little increase of irritation could not fail

101

to disorder, or to break oft'. Those who have practised in great hospi-
tals, know to how many patients indigestions are fatal. I have seen some
•with large ulcers; suppuration was copious and healthy; the granula-
tions florid, and all promising a happy issue, when ignorant friends bring
them by stealth indigestible food, with which they cram themselves, in
spite of the utmost watchfulness. The stomach, used to mild and mode-
rate regimen, at once overloaded with food, is changed into a centre of
fluxion, towards which the blood all tends. An irritation is produced
beyond that on the ulcerated surface ; which, in a little time, ceases
to secrete pus, the fleshy granulation become flabby, extreme op-
pression is felt ; with a difficulty of breathing comeson a pungent pain in
the side, the pain sympathetically felt in the lungs, makes this organ the
seat of an inflammatory and purulent congestion, a rattle ensues, and the
patients die of suffocation, at the end of two or three days, sometimes
in twenty-four hours; and this fatal termination is especially accelerated,
when, as I have often witnessed, a blister is applied to the seat of the
pain, instead of the ulcerated surface.

It will seem surprising, perhaps, that in the case of which I have just
been speaking, it should be in the lungs, and not the stomach itself, that
the congestion and the pain take place; but besides that the most per-
meable organ of the body, is the lungs, as well as the weakest, and the
most easily yielding to fluctionary motion* ', a host of instances prove, what
a close sympathy unites it to the stomach. Let us but call to mind pleuri-
sies and bilious peripneumonies, those acute pains of the side, which,
since Stahl, physicians have so successfully treated with vomits. The
rapidity with which their symptoms go off, on the evacuation of the
sordes which oppress the stomach, shows clearly that the sympathetic
diseases are not owing to the metastasis of bile upon the lungs, and that
they do not consist in the simultaneous existence of a gastric affection,
and of an inflammatory state of the pleura or of the lungs, but that they
are simple gastric affections, in which the lungs are, at the same time,
the seat of a sympathetic pain.

The action of the parietes of the stomach ceases, only when this viscus
is completely cleared of the food it contained. The gastric juice, no
longer secreted, ceases to be poured so freely by its arteries, and the
parietes, which close upon each other, are chiefly lubricated by the
mucus so plentifully secreted by the inner coat.

At times, the action of the muscuiarfibresof the stomach is altogether
inverted, they contract from the pyloris, towards the cardia, and this
anti-peristaltic motion, in which the contractions are effected with more
force, more rapidly, and in a manner really convulsive, produces vomit-
ing. Then, the action of the abdominal muscles is added to that of the
stomach ; the viscera are driven upwards and backwards, by the contrac-
tion of the larger muscles of the abdomen ; the diaphragm rises up to-
wards the chest. If it sunk as it contracted, the oesophagus, which
passes in the interval of its two crura, would be compressed, and the pas-
sage of the alimentary substances by the cardiac orifice, could not take
place. Accordingly it is observecJ, that it is only during expiration, that
any thing passes from the stomach into the oesophagus. Vomiting may

* Of all the erg-ads it is that in which we most meet with organic injury; and those
who have opened many bodies, may have observed, how rare it is to find the lungs
completely sound in adults and in old men. — Author's J\ *ote.

102 . |||

depend upon the obstruction of the pylorus*, on the too irritating impres-
sion of any substance on the coats of the stomach ; it may be produced
by the irritation of some other organ with which the stomach is in sym-
pathy, &c.

Digestion in the stomach is essentially assistefl by nervous influence.
Many physiologists, since Brunner, have found that the tying of the eighth
pair of nerves (the pneumo-gastric) provoked vomiting and retarded
the work of digestionf. As it is impossible to make this experiment
without effecting respiration, a function of very different importance, it
becomes difficult to know, whether the derangement of digestion did not
proceed from the general disturbance brought upon all the functions:
however, the brain does appear to be in more immediate sympathy with
the stomach, than with any other part of the digestive tube. Disgust
from the recollection of loathed food excites vomiting. A more than
ordinary exertion of the brain relaxes, disorders, and will even suspend,
altogether, the functions of the stomach: an unexpected piece of news,
a violent emotion, are attended with a cessation of the strongest sensation
of hunger. It would be useless to bring together, in this place, proofs of
the intimate connexion subsisting between the brain and the stomach,
through the intervention of the pneumogastric nerves, for the connexion
is questioned by no onej.

XXV. Of Digestion in the Duodenum. The food, on quitting the sto-
mach, enters the duodenum, and there experiences new changes, as es-
sential as those which were produced upon it, by digestion in the sto-
mach. It might even be said, that as the essence of digestion and its
principal object is the separation of the food into two parts, the one re-
crementitious and the other chylous or nutritious, the duodenum, in
which that separation is performed, is its principal organ. In fact, how-
ever carefully one may examine the greyish chyme which is sent out of
the stomach, it will be discovered to be a mere slimy homogeneous pulp ;
and in more than a hundred animals which I have opened during the pro-
cess of digestion, I never observed the absorbents of the stomach filled
with real chyle, like those of the intestines.

The duodenum may be considered as a second stomach, very distinct
from the other small intestines, by its situation exterior to the perito-
neum, by its size, and by its readiness of dictation, the size and regula-
rity of its curvatures, the great number of valvulse conniventes with
which its inner part is furnished, the prodigious quantity of chylous ves-
sels which arise from it, and especially by its receiving, within its cavity,
the biliary and pancreatic fluids. If the situation of the duodenum and
the peculiarities of its structure are attended to, it will be readily observ-
ed, that every thing in that intestine, tends to slacken the course of the

* The best description of the pyloris is given by BLUMEJTBACH from LEVELLING,
who designates in an annular fold, " consisting1 not, like the other i-ugac of the stomach,
of merely the mucous, but also of fibres derived from the nervous and musular coats.
All these, united, form a conoidal opening' at the termination of the stomach, project-
ing- into the duodenum, as the uterus docs into the vaginia, and, in a manner, embraced
by it."— Copland.

•\ Dr. Haig-hton lias proved, in the most satisfactory manner, that a lig-ature on the
eighth pair of nerves, far from inducing- vomiting-, renders the stomach incapable of
rejecting its contents, even though excited by the most powerful emetics. — See Me-
znoirs of the London Medical Societv Trans. Vol. II. P- 512. — DeLvs.

* See APPENDIX, Note L.

103

alimentary substance, and to prolong its stay within it, that it may re-
main the longer exposed to the action of these fluids.

The duodenum is, in fact, almost entirely uncovered by the peritoneum,
a serous membrane, which like all those that line the inside of the great
cavities, and reflect themselves over the viscera which they contain, by
furnishing them external coverings, admits but of little extension, and
seems to stretch, when these viscera become dilated, only by the unfold-
ing of its numerous duplicaiures. Fixed by a rather loos* cellular tissue
to the posterior side of the abdomen, the duodenum is susceptible of such
dilatation, as to equal the stomach in size, as is sometimes seen in open-
ing dead bodies. Its curvatures depend on the neighbouring organs, and
seem almost invariably fixed; lastly, numerous valyulse line its inner sur-
face, so as to add to the friction, and to increase the extent of surface, and
thereby the number of absorbents destined to take up the chyle separated
in the duodenum, from the excrementitious part of the food, by the action
of the fluids poured into it, from the united ducts of the liver 'and pan-
creas*.

XXVI. Of the Bile and of the Organs which serve for its secretion. The
bile is a viscous, bitter, and yellowish fluid, containing a great quantity
of water, of albumen to which it owes its viscid condition, and oil to
which the colouring and bitter principle is united. Soda, to which the
bile owes the property of turning vegetable blues to a green colour, phos-
phates, carbonates, and muriates of soda, phosphates of lime, and of am-
monia j and, lastly, as some say, oxide of iron, and a saccharine substance
resembling the sugar of milk. This fluid, which the ancients Looked upon
as animal soap, fitted for effecting a more intimate mixture of the alimen-

* The muscular coat of the duodenum is thicker than that of the small intestines,
the base of the villi of the mucous tunic is more thickly set with glandular follicles,
and the wjiole duodenum presents a more vascular appearance than any other portion
of the intestines.

The experiments of Dr. PROUT on chyme, taken from the duodenum, exhibit the
following1 results : —

1. VEGETABLE FOOD.

Composed of a semi-fluid, opake, yellowish white part, having- mixed with it an-
other portion of similar colour, but of firmer consistence. It coagulated milk com-
pletely.

AVater, 86-5

Chyme, &c g.

"Biliary principle, . . . , 1-5

Vegetable gluten, .... 5.

Saline matter, «... .7

Insoluble residuum, ... -2

100
2. ANIMAL FOOD.

More thick and viscid than chyme from vegetable food, and its colour more inclining:
to red. Did not coagulate milk.

Water, 80-

Chyme, &c. .
Albuminous matter
Biliary principle,
Saline matters,
Isoluble residuum,

15-8

1-3

1-7

•7

•5

100

104

tary matter, by combining its watery with its fat and oily, parts, is there-
fore, extremely compound : it is at once watery, albuminous, oily, alka-
line, and saline*. The liver which secretes it, is a very bulky vis-
cus, situated in the upper part of the abdomen, and kept in its place,
chiefly by its attachment to the diaphragm, of which it follows all the
motion.

The hepatic artery, which the creliac sends off to the liver, supplies it
only with the blood requisite for its nutrition : the materials of its secre-
tion are brought by the blood of the vena portse.

This opinion on the uses of the hepatic artery, which I take up with
Haller, cannot rest upon the experiments of those who pretend to have
seen the secretion of the bile going on, after it was tied. Besides that
the position of this vessel makes the operation almost impossible, which
gives me reason to doubt if ever it was practised ; and if it were, by in-
tercepting the course of the arterial blood carried to the liver, this viscus,
even under the received hypothesis, would remain deprived of nourish-
ment and of action : and the vena portse would supply it, in vain, with a
blood on which it could exert no influence* When this vein is tied, which
it is far more easily done than the artery, the secretion of bile is seen to
stop; but the experiment which suspends the abdominal venous circula-
tion, is too speedily fatal, to justify any conclusive inference. It is on
analogical proofs, that the received hypothesis rests, touching the man-
ner of the biliary secretion. The hepatic artery, remarkably lessened by
the branches it has sent off in its way towards the liver, is to that organ
what the bronchial arteries are to the lungs; and in the same manner,
the branches of the vena portae, spread through its substance, may be
compared to the system of pulmonary vessels. It is still to be confessed,
however, that the enormous bulk of the liver, its being found in almost
all animals, and the quantity of blood carried into it by the vena portae,
compared to the small secretion there is of bile, lead to the belief that the
blood sent to it from all the other organs of digestion, undergoes changes
there, on which science possesses, as yet, no certain data, though the
chemists maintain, that the liver is, in some sort the supplementary
organ of the lungs, and assists in clearing the blood of its hydrogen and
carbon.

* " Human bile differs considerably from that of all other animals. Its colour is
sometimes green, sometimes yellowish brown, aud sometimes it is nearly colourless.
Its taste is not very bitter. It is seldom completely liquid, but usually contains some
yellow matter suspended in it. When evaporated to dryness, it leaves a brown mat-
ter amounting to about 1-1 1th of the original weight. When this matter is calcined,
it yields all the salts which are to be found in the bile. All the acids decompose hu-
man bile, and throw down a copious precipitate, consisting of albumen and resin."-—
Thomson's Chemistry, &c.
The following is the analysis of human bile according to BERZEMUS :—

Water, 908-4

Picromel, 80-

Albumen, 3'

Soda, 4-1

Phosphate of lime, ....

Common salt, .... 3-4

Phosphate of soda with some lime, 1 •

1000

Copland.

105

This nanle of venaportx is given to a peculiar venous system, enclosed
in the abdominal cavity, and formed as follows: The veins which bring
back the blood of the spleen, and the pancreas, of the stomach and intes-
tinal canal, are united in a very large trunk, which ascends towards the
concave face of the liver, and there divides into two" branches*. These
lie in a deep fissure in the substance of this viscus; they send out,
through all its thickness, a multitude of branches, which divide like ar-
terial vessels, and end, in part, by opening into the biliary ducts or pores,
and, in part, by producing the simple hepatic veins. These veins, situ-
ated chiefly towards the convex or upper surface of the liver, bring back,
into the course of the circulation, the blood which has not been employ-
ed in the formation of bile, and that which has not served to nourish the
substance of the liver: for^ they arise equally from the extremities of
the vena portae, and from the extremities of the ramifications of the he-
patic arteryf.

The liver differs from all organs of secretion, in this, that the materi-
als of the fluid it elaborates, are not supplied to it by its arteries. It
should seem that the bile, a fat and oily fluid, in which hydrogen and car-
bon predominate, could be drawn only from venous blood, in which, as is
known, these two principles are in superabundance. The blood acquires
the venous qualities, as it passes along the circuitous course of the circu-
lation, and is supplied with hydrogen and carbon the more fully, the
slower it flows. Now, it is easy to see, that all is naturally disposed for
slackening the circulation of the hepatic blood, and to give it, eminently,
the distinguishing properties of venous blood. The arteries which fur-
rush blood to the organs, in whkh the vena portae rises, are either verv
flexuous as the splenic, or frequently anastomose, like the arteries of the
intestinal tube, which of all that are in the body, abound most in visible
divisions and anastomoses. It will be seen in the chapter on circula-
tion, how well these dispositions are adapted for retarding the course
of the arterial blood. Once carried into the organs of digestion, the
blood stays there, whether it be that the coats of the hollow viscera be-
ing collapsed or closed upon themselves, hardly yield it passage, or
that the organization of some one of these viscera is favourable to its
stagnation.

The spleen seems to serve this purpose. Does this dingy and soft
viscus, lodged in the left hypocondrium, and attached to the great fundus
of the stomach, receive the blood into the minute cells of its spongy pa-
renchyma, or does this fluid merely traverse, very slowly, the delicate
and tortuous ramifications of the splenic vessels? In other respects, there
is no organ that exhibits more variety of number, of bulk, of figure, of
colour, and of consistence. Sometimes manifold, often divided into se-

* Professor Louis JACOBSOX, has made a very important discovery in comparative ana-
tomy relative to a venous system going- to the kidneys, analogous" to the portal system
ofthe liver. A translation ofhis Observations has been published in the Philadelphia
Medical Journal, vol. 6, p. 87. We have satisfied ourselves of his con-ectness, espe-
cially by an examination of these veins in the sturgeon. — Godman,

In two instances the vena ports has been found running, not to the liver but di-
rectly to the vena cava inferior. One of these is described by Mr. AHERNETHT, in Vol.
LXXXI1I. of the Philosophical Transactions, and the other by Mr. LAWRENCE, in Vol.
IV. ofthe Medico-Chirurgical Transactions.— Copland.

For some observations on the structure and actions ofthe liver, see APPENDIX
M.

veral lobes by deep clefts; its bulk varies, not only in different individu-
als, but even in the same, at different times of the day, as the stomach,
full or empty, admits or rejects the arterial blood, and compresses the
spleen between its large extremity, and the ribs under which it is situa-
ted, or leaves it free.

The blood which fills the tissue of the spleen, blacker, more fluid, rich-
er in oily principles, owes all these qualities, which led the ancients to
consider it as a peculiar substance, called by them the atra bilis, or black
bile, to its long protracted continuance within that viscus* The branches,
which by their union form the vena portse, have thinner parietes than
the other veins of the body, they are not furnished with valves, and they
do not readily free themselves of the blood which fills them. The action
of these veins is, in fact, so feeble, that it would not suffice to enable
them to carry the blood onward, if the gentle and alternate compression
of the diaphragm and abdominal muscles on the viscera of the abdomen,
did not favour its circulation. On reaching- the liver, the blood, which
is highly venous, is further slackened in its circulation, by the increased
dimensions of the space in which it is contained, the united calibre of
the branches of the hepatic vena portae, exceeding considerably that of
the principal trunk. Besides, these vessels are enveloped in the paren-
chymatous substance of the liver, and can act but feebly. It, therefore,
circulates slowly through that organ, and, with difficulty, returns into
the course of circulation. The hepatic veins, which are of rather con-
siderable calibre, and without valves, remain constantly open, their pa-
rietes cannot close and contract on tlie blood which fills them, on account
of their adhesion to the parenchymatoixs substance of the liver. They
open into the vena cava, very near the place' at which that vein termi-
nates in the right auricle. The regurgitation of the blood, during
the contraction of that cavity of the heart, is fek in the veins, and the
blood forced back towards the liver, is exposed for a longer time to
its action.

The spleen, therefore, performs only preparatory functions, and may
he considered as the auxiliary of the liver, in the secretion of the bile*.
It is observed, that the quantity of the latter increases, after the spleen
has been extirpated, and that it is less yellow, less bitter, and always im-
perfect. The blood which circulates in the omentum, is very similar to
that of the spleen; I would even say, that it contains oily particles, if
the drops which I have clearly noticed on its surface, might not have
come from the adipose tissue of the omentum, which allows the fluid con-
tained in its cells to flow, when a small puncture is made into it, in exa-
mining the blood contained in its veins.

The bile secreted in the tissue of the liver f is absorbed by the biliary
ducts, the union of which forms the hepatic duct. The latter issues from
the concave surface of the liver, and conveys the bile, either immediately
into the duodenum, by means of the ductus communis choledochus, or
into the gall bladder. This small membranous pouch, which adheres by
means of cellular tissue to the lower surface of the liver, is in some ani-
mals entirely distinct from that organ, and connected to it, only by the in-

* On the subject of cystic and hepatic bile, the student will do well to consult BICHAT
on tJie membranes, p. 61, &c. — Godman.

•j- See APPENDIX, Note N, for an account of the latest observations and opinions
respecting the structure and functions of the spleen. — Copland.

107

sertion of its duct, into that which comes from the liver. Its inner mem-
brane is soft, fungous, plicated, and always covered with the mucus, se-
creted by the glandular criptae which it contains. This mucus defends
the gall bladder against the action of the bile which it contains. The al-
most parallel course of the hepatic and cystic ducts, the acute angle at
which they meet, renders it difficult to account for the passage of the
bile into the gall bladder. It appears, that when the duodenum is empty,
the bile regurgitates, in part, from the hepatic duct in the gall bladder,
collects within it, becomes thicker and yellower, and requires a greater
degree of bitterness. Consequently, the use of the gall bladder, is to serve
as a reservoir to a portion of the bile, whiclj, by remaining within it, is
improved in quality, acquires consistence and bitterness, and is heighten-
ed in colour, by the absorption of its fluid parts*.

XXVII. The irritation produced on the parictes of the duodenum,
when distended by the chyme, is propagated to the gall bladder, by the
cystic and common ducts. Its parietes then contract, and oblige the bile
to flow, along this cystic duct into the ductus commimis choledochus.
The pressure of the distended intestines on the gall bladder, favours the
excretion of bile. The hepatic bile is also more abundantly poured into
the duodenum during digestion, from being secreted in greater quantity
by the liver, which participates in the irritation affecting the organs of
digestion, and secretes a greater quantity. The cystic and hepatic bile,
mixed in the ductus communis choledochus, undergoes a change before
entering the duodenum, by uniting with the fluid of the pancreas. The
excretory duct of the pancreas, a glandular organ, which, in structure,
bears so great an analogy to the parotid glands, thatsonje physiologists,
assuming an identity of functions, have called it the abdominal salivary
gland, joins the biliary duct, before the latter c>pens in the duodenum,
after having insinuated itself obliquely between the coats of that intes-
tine. It arises within the pancreas, from<t great number of radicles
which join it, like the feathers of a quill t» a common trunk. Its calibre
increases in size as it approaches the l^ge end of the pancreas, situated
on the right, in the concavity of the pecond curvature of the duodenum.
Nothing precise is known, with regard to the nature of the pancreatic
fluid ; the striking resemblance of the pancreas to the salivary glands
leads to a presumption, that t^s fluid bears considerable analogy to the
saliva. The quantity of fluid secreted by the pancreas is likewise
unknown, but it must be considerable, if one may judge from the great
number of nerves and vessels which pervade its glandular tissue, and its
quantity is, most probably, increased by the irritation of the food in the
duodenumf.

* See, in the cliapteron secretion, the laws which that function obeys. — Copland.

•\ Opinions are various respecting the quantity of the secreted fluid which the pan-
creas yields. AUTEXIUETII reckoned the quantity at nine ounces tiie twenty-four
hours. It has been generally supposed that this secretion is considerably augmented
At the time that the chyme flows into the duodenum ; and the intimate connexion
existing1 between the ganglial nerves, supplying- these viscera, favours the conclusion.
MAGENDIE, however, rejects this inference, and inserts, without stating the grounds
of his opinion, that the flow of the pancreatic juice is least abundant during digestion.

The disordered functions of this organ appear to be very essentially concerned in
the production of some diseases which are too often referred entirely to the stomach
and small intestines, which, no doubt, become consecutively deranged from this cause ;
or, if the actions of the pancreas be not primarily diseased, a co-existent disorder may be
present in these allied viscera, and be equally the result of one cause. — Copland.

108

This combination of the united pancreatic and biliary fluids poured on
the chyme, penetrates it, renders it fluid, anamalizes it, separates the
chylous from the excrementitious part, and precipitates whatever is no:
nutritious. In bringing about this separation, the bile itself seems to be
divided into two parts, its oily, coloured, and bitter portion passes along
Avith the excrements, sheathes them, and imparts to them the stimulating
qualities necessary to excite the action of the digestive tube. Its albu-
minous and saline particles combine with the chyle, become incorporated
lo it, are absorbed along with it, and return into the circulation. There
may, in fact, be noticed in the alimentary mass, after it has undergone
this combination, two very ^distinct parts, the one is a whitish milky sub-
stance, which swims to the surface, and is the least in quantity ? the
other is a yellowish pulp, in which, when digestion is healthy, it is not
easy to recognize the nature of the food. When the liver is obstructed,
and the bile does not flow in sufficient quantity, the faeces are dry and
discoloured; the patients are troubled with obstinate costiveness, the
excrement, uncombined with the bitte? and colouring matter of the bile,
not proving sufficiently irritating to the intestinal canal.

We have just mentioned how the separationof the chyle is performed;
but the mechanism of that separation and the process of chylification are
absolutely unknown. How does the union of the bile to the chyme ope-
rate, in extracting- from the latter the recrementitious part, and in making
it swim above the rest? Is there any connexion between that process and
the nature of the constituent principles of the bile ? The knowledge of
the composition of the bile, affords as little assistance in the explanation
as does the knoAviedge of the chemical properties of the semen, in under-
standing the admirable function of generation. All these acts of the ani-
mal economy, are as mysterious and inexplicable, as the action of the
brain in producing thought, a phenomenon which so many physiologists
have considered as exceeding the power of matter, and for which they
seem to have reserved all th-oir admiration, though nil mirari, which I
would translate by wondering at nothing, ought to be the motto of any one
-who has made some progress in ti-e study of the laws of life.

XXVIII. Of the action of the smalt Intestines. After remaining a certain
time within the duodenum, the alimentary mass decomposed by the bile,
or rather by the pancreatico-biliary fluid separated into two parts, the
one chylous, the other excrementitious, passes into the jejunum and
ileum, which are not easily distinguished from each other, and which dif-
fer in their relative length, according to the elements on which anato-
mists ground the distinction*.

* The redness of the parietes of the jejunum, the empty condition of that intestine,
its situation in the umblical region, the great number of its valvulze conniventea, do not
distinguish it from the ileum, for, the colour of the intestinal canal varies in different
parts (/fits extent, and the substances which fill it are found in different parts of the
canal, according to the progress of digestion at the time the parts are examined ; ac-
cordin0' as the convolutions are situated within the cavity of the pelvis, or rise towards*
the epigastric region ; according to the full or empty state of the bladder and stomach -r
and the number of circular folds, called valvulse conniventes, diminishes, as on-e gets-
near to the termination of the ileum. Winslow got over the difficulty, by considering;
tile upper two-fifths of the small intestines as jejunum, and the remaining three-fifths
as ileum. This last division, from measurement, is wholly arbitrary, and is besides
useless, for there is not, perhaps, above one occasion in which it would be interesting
to distinguish the jejunum from the ileum. In operating for hernia, when the intes-

The jejunum and the ileum alone occupy nearly three-fourths of the
whole length of the digestive canal ; they are straiter than the duodenum,
and do not dilate so readily, because the peritoneum, which forms their
outer covering, lies over their whole surface, with the exception of the
posterior border at which their vessels and nerves enter. It is along
that border, that they are fixed to the mesentery, a membranous band
formed by a duplicature of the peritoneum, which contains the vessels
and nerves going- to the jejunum and ileum, which prevents knots from
forming in the intestines, and is a security against the occurrence of
intus-susceptio. It is well known, however, that in some rare cases, in-
tus-susceptio does take place, with utmost danger, of the patient's life,
who generally dies in the agonies of insufferable cholic pains, which
nothing can alleviate. The progress of the food, along the small in-
testines, is retarded by its numerous curvatures, very aptly compared
by some physiologists to the windings of a meandering stream which fer-
tilizes the soil it waters. These numerous convolutions of the intestinal
canal favour the long continued presence of the food within its cavi-
ty, so that the chyle expressed from the excrementitious part by the
peristaltic contractions of the intestine, may present itself to the inha-
ling mouths of the lacteals, by which it is to be absorbed. These chy-
lous absorbents are in greater number on the surface of the valvulae
conniventes, which are circular folds of the inner membrane, and these
are at a greater distance from each other, the nearer they are to the ter-
mination of the ileum. The valvulae conniventes not only slacken the
progress of the food, but by their projections, they sink during the con-
traction of the bowels, into the alimentary mass, and the lacteals on their
surface take up, from its inmost part, the chyle which they are destined
to absorb*.

The number of the valvulae conniventes diminishes with that of the
lymphatics. The progress of the alimentary substance is gradually ac-
celerated, as it parts with its nutritive and recrementitious particles. A
quantity of mucus, secreted by the internal membrane of the small intes-
tines, envelopes the chymous mass and promotes its progress, by lubri-
cating it : this intestinal mucus thrown out by the exhalant arteries, im-
bues it, renders it liquid, and adds to its bulk. This fluid which seems to
partake of the nature of albumen and gelatine, and to hold several saline
substances in solution, is, for the greater part, recrementitious, and must
be very considerable in quantity, if we may judge from the calibre of the
mesenteric arteries, and from the extent of the internal surface of the in-
testines. It is, however, scarcely possible, that this exhalation should
amount to eight pounds in twenty-four hours, according to Haller's cal-
culation, who, as we shall observe, when we treat of the secretions, has
generally over-rated their amount.

The peristaltic contractions, by the assistance of which, the alimentary
mass is sent along the whole course of the small intestines, do not occur
in a regular and uninterrupted succession, from the stomach to the
coecum. This undulatory and vermicular motion manifests itself at once,

tine is mortified, one would decide the more readily to leave an artificial anus, if one
could be sure that the gangrenous portion belonged to the latter intestine ; but of this
it is absolutely impossible to be certain.— -.Star's Note.

* See APPENDIX, Note O, for some remarks respecting1 the mucous coat of the
digestive eaual, and the functions of" the small and large intestines Copland.

110

in several points of the length of the tube, whose curvatures straighten
themselves at intervals. In this action, the intestinal curves are decom-
posed into a great number of short straight lines which meet, so as to
form obtuse angles. The peristaltic motion which affects the muscular
fibres of the intestines, is caused by the irritation of the alimentary sub-
stance on the sentient parietes of the canal along which it descends, to-
wards the great intestines. The jejunum and the ileum, covered by the
peritoneum, except at the part which connects them to the mesentery, at
the time of dilatation, separate the two peritoneal laminae, forming the
mesentery. They occupy the space between the branches of the mesen-
teric vessels, whose last division is always at some distance from the ad-
hering edge of the intestine. If this division of the vessels had taken
place, nearer to the union of the intestine and mesentery, the intestinal
canal would not have admitted of dilatation, without stretching the ves-
sels situated at the angle of separation. It is likewise observed, that in
the portions of the digestive tube which are most susceptible of dilata-
tion, the last vascular divisions are most distant. Hence the left gastro-
epiploic artery is always at a greater distance from the great curvature of
the stomach, than the right, a circumstance of which no anatomist has
hitherto taken notice.

XXIX. Of Digestion in the Great Intestines. The alimentary mass, after
it has parted with nearly the whole of its nutritive particles, passes from
the ileum into the coecum ; it then is received into the great intestines,
which aie more spacious, though shorter, than the small, forming scarce-
ly, a fifth of the whole length of the digestive tube.

A musculo-membranous valvular ring is placed at the oblique insertion
of the ileum into the first of the great intestines. This valve, called after
Eustachius or Bauhinus, who are considered as its discoverers, though
the merit of the discovery belongs to Fallopius, is formed of two semi-
circular segements, the right edge of which is free, and floats towards the
cavity of the coecum. The more the parietes of that intestine are dis-
tended by the substances which it contains, the greater is the difficulty to
the retrograde flow of such substances, for under those circumstances,
the two extremities of the valve are at a distance from each other, and
its edges, which are free, close on each other, like those of a button-hole
whose angles are drawn in opposite directions; besides, the muscular
fibres which enter into its structure, render it capable of exerting con-
striction. It is, therefore, calculated to permit the ready flow of matter,
from the ileum into the coecum, and forcibly prevent their return in-
to the small intestines. There are facts which lead to a belief, that its
resistance is sometimes overcome, and that a clyster, thrown in with
violence, would force the valve, and be thrown up by vomiting. The
great intestines may be considered as a kind of reservoir destined to
contain, for a certain time, the excrementitious residue of our solid ali-
ments, so as to save us the disgusting inconvenience of constantly part-
ing with it.

As the peritoneum does not wholly cover the great intestines, they
are capable of considerable dUitation, and of extending into the cellular
substance which connects them to the posterior part of the abdomen.
Their muscular coat which, in a manner, is the base of the intestinal
tube, does not consist throughout, of circular and longitudinal fibres. The
latter, collected into fasciculi, form three narrow bands, in the intervals
of which, the parietes of the gut are exceedingly weakened, and conse-

Ill

quently capable of greater extension. These longitudinal fibres being*
besides, shorter than the intestine, crease it transversely, and form with-
in it a number of cavities and cells, marked outwardly by prominences,
separated by depressions. If, in addition to the peculiarities of struc-
ture, it be considered, that in the ccecum and a great part of the colon,
the contents of the bowels have to ascend against their own weight; that
the curvature forming the sigmoid flexure of the colon is very considera-
ble, and that, in short, (he rectum before its outer termination in a nar-
row aperture, is considerably dilated, it will be evident, that in the great
intestines, every thing tends to protract the stay of the excrements.

The appenclicula vermi-formis of the coecurn is, in man, too small to
perform this office; in the herbivorous quadrupeds, in which it is much
larger, and sometimes not single, it may serve as a reservoir to the faecal
matter. Its existence merely shows, in man, an analogy to those animals
in which it is truly useful, and it concurs in manifesting, that Nature, in
the formation of particular organs, in certain kinds of animals, aims at a
mere outline which she fills up in others, to show, as it were, that there
are points of resemblance between all beings whom she has gifted with
life and motion*.

While in the great intestines, the alimentary substance becomes mere-
ly faecal, by parting with the small quantity of chyle which it may yet
contain. The number of the absorbents decreases progressively from
the coecum to the rectum ; the small number of these vessels, accounts
for the difficulty of throwing in nourishment by means of clysters, when
there is an obstruction to deglutitionf. The excrements thicken, harden,
and become formed or moulded, in the cells of the colon, they are then
urged by the peristaltic action, into the rectum, in the cavity of which
they accumulate, till they excite on its parietes an action which deter-
mines their expulsion.

XXX. Of the evacuation of the faces. When a call to evacuate the faeces
is experienced, the rectum contracts, while the diaphragm descending,
.and the abdominal muscles receding towards the spinej, thrust the vis-
cera of the abdomen towards the cavity of the pelvis, and compress the
intestines which are filled with fsecal matter. During these efforts, the
perineum perceptibly descends, and the fibres of the levator ani are
somewhat elongated. The combined action of the rectum and of the
abdominal muscles, overcomes the resistance of the sphincters, and the

* The number of these appendages is very great in some of the interior animals,
especially in some of the fishes. See Cuvier, An. Comp. — Godman-

\ Some physiologists have considered as unnecessary, this concurrent action of" the
diaphragm and abdominal muscles ; they ground their opinion on the circumstance,
that animals whose abdomen has been laid open are capable of voiding their faeces.
Astruc, one of the luminaries of Montpellier, denies the action of the abdominal mus-
cles, in the efforts which one makes at stool, and in support of his opinion, he brings
forward this geometrical proposition, " that a cord disposed in the form of a circle,
can, by contracting, shorten itself in an infinitely small degree, and, therefore, not
perceptibly." On which Pitcairn humorously enough observes, that Astruc had never
practised what he reasons upon :— ." credo Jlstrucciwn nunquam cacasse. — Jluthor's
Note.

* Tliis is one, but not the only reason, why the system cannot be sustained for any
length of time by injections. For the formation of chyle, containing the elements of
blood, which it always does when genuine, it is indispensably necessary that the aliment
should be previously converted into chyme, an operation -which seems, from experi-
ments, cannot be effected in the great intestines. — Chapman.

its

alvine evacuation takes place, and is facilitated by the secretion of the
mucous follicles of the rectum: these glands, squeezed by the pressure
of the faeces, pour out their contents, and lubricate the circumference
of its lower aperture. When the faeces have been voided, the dia-
phragm rises, the large muscles of the abdomen cease to press backwards
and downwards upon the viscera of that cavity; the perineum ascends
and the sphincters close, till a renewal of the same call, again brings on
the same action.

The call to avoid the fseces, is more frequent in children than in adults,
because, at an early period of life, the sensibility of the intestinal canal
is greater, the contents of the bowels more fluid, and digestion more ac-
tive. As we advance in years, sensibility becoming impaired, and con-
tractility experiencing a proportionate loss of power ; the secretions be-
ing, likewise, less abundant, the bowels become sluggish, the stools more
scanty and indurated. They are, likewise, less frequent and copious in
women than in men, whether it be, that the digestive power extracts
from the aliment, a greater proportion of nutritious matter, or that the
menstrual evacuation being a kind of substitute for the intestinal secre-
tions, less remains to add to the bulk of the excrementitious mass. The
evacuation of the faeces may be brought on by throwing liquids into the
rectum, which dilute the faeces, detach them from the parietes of the in-
testines, and, exciting on these parietes an irritation to which they are
not accustomed, determine their contraction.

The fetor of the excrements depends on their incipient putrefaction
in the great intestines. This decomposition is, almost always, attended
with the extrication of gases, in which sulphurated hydrogen prevails.
This gas, which at times escapes, and which at others impregnates the
faeces, is the cause of the black colour which they give to silver exposed
to their action. One may recognize in the excrements the colouring-
matter of vegetables, such as the green colour of spinage, the red of beet-
root; one may, likewise, find among them, the fibrous parts of plants and
animals, the indurated bark, and the seeds covered with their husks.
The digestive juices have so little action on husks, that seeds which
have not been broken down by the organs of mastication, frequently con-
tinue capable of vegetation.

During the process of digestion, the food contained in the stomach and
intestines absorbs or extricates different gases. M. Jurine, of Geneva,
opened the body of a maniac who had been dead a few hours, and collect-
ed the gases which escaped; he observed, that the proportion of oxygen
and carbonic acid diminishes from the stomach towards the great intes-
tines, while on the contrary, there is, in these, an increased proportion of
azote ; that hydrogen is more abundant in the great than in the small in-
testines, that it is less in quantity in these than the stomach*. Do the
oxygen and azote form a part of the atmospherical air which is taken in
with the food and with the saliva, and which is disengaged by the heat
of the intestinal canal ? Or are these gases the result of the decomposi-
tion of the food and of the intestinal fluids? Besides, may not the gas
contained in the intestines of a dead body, have been formed at the
moment of death ? We know that in several instances, at the moment
contractility is forsaking our organs, the intestines become distended by

* See APPENDIX, Note C.

113

gas which hastens the approach of death, by impeding the descent of the
diaphragm.

Digestion, when healthy, is unaccompanied by the production of gases.
In indigestion, there almost always escapes carbonated or sulphureted
hydrogen gas, which produces the offensive smell of the air which es-
capes at the anus: this smell is different from that of the flatus which are
brought upwards, these contain pure hydrogen or carbonic acid gas. The
latter is, likewise, sometimes voided by the rectum, but less frequently
than hydrogen combined with carbon, sulphur, or even phosphorus. Is
not ammonia itself extricated, and does it not accompany the evacuation
of the faeces in certain putrid diarrhoeas, as indysg|tery combined with
low fever ? Though the formation of this gas implies a putrefactive mo-
tion opposed to the vital principle, may not this decomposition com-
mence in substances lying in the great intestines, when these are be-
come almost inert from the impaired condition of the vital power. This
would riot be the only instance of a chemical process taking place in the
intestinal canal, notwithstanding the counteracting influence of vitality.
Thus, on some occasions, grapes eaten in too great quantity, ferment and
produce carbonic acid gas, in such abundance, that this elastic fluid over-
comes the resistance of the intestines. This is the kind of distension
from flatulence which is cured by drinking plentifully of cold water,
which dissolves the gas naturally soluble in that fluid.

XXXI. Of f/ie secretion and excretion of the Urine. The fluids absorb-
ed with the chyle, and taken up by the lymphatics of the intestinal tube,
dilute the nutritive part extracted from the solid aliment, and serve it as
a vehicle. When they have reached the mass of the bfood, they increase
its quantity, diminish its viscidity, and render it more fluid ; going along
with it throughout the whole course of the circulation, they supply moist-
ure to all the parts of the body, and become loaded with the molecules
detached from them by the vital motion. Then, conveyed to the urinary
organs, they become disengaged from the rest of the fluids, carrying
along with them a number of products of every kind, which by a longer
stay in the animal economy, would not fail to occasion a manifest distur-
bance in the exercise of the functions.

XXXII. The rapidity with which we void, with the urine, certain diu-
retics, has induced several physiologists to think, that there exists a di-
rect communication between the stomach and bladder: no one, however,
has ever succeeded in pointing out those peculiar ducts, which might
serve to convey the urine from the stomach to the urinary organs, with-
out taking the circuitous course of absorption and of the circulation, and,
besides, the learned Haller has proved, by accurate calculations, that the
size of the renal arteries, 'whose calibre amounts to an eighth of that of
the aorta, and the quickness with which che blood flows, sufficed to ac-
count for the shortness of the time in v-nich certain fluids reach the uri-
nary organs*.

* The experiments of Dxnwnr wit* the nitrate of potash, and of BRAND B with the
prussiate of potash, have led severs'* i'1 modern times, and amongst these, Sir EVERARD
HOME, to support the opinion allied to above. MAGENDIE made experiments in order
to ascertain this matter, and deuced from them the following inferences :—

1. Whenever the prussiate of potash is injected into the veins, or absorbed from the
Intestinal canal, or from a jerous surface, it passes quickly into the bladder, where it
may be easily recognized m the urine. 2. Whenever a very considerable quantity of

P

114

A thousand ounces of blood pass through the renal tissue in the space
of an hour : supposing that this fluid contains only a tenth of the materi-
als fit for supplying urine, a hundred ounces, or seven pounds and a quar-
ter, may be given out in this short time; and never, with the most co-
pious and diuretic drinks, does more of it pass in an hour. We shall
see, however, in treating of absorption, that it is not absolutely impossi-
ble, that by means of the numerous anastomoses of the lymphatics, this
set of vessels may carry a liquid, directly from the stomach into the blad-
der. It would be superfluous to mention, in this place, the varieties ob-
servable in the kidneys, in point of number, size, and situation. These
two lobular viscera,xomposed of the union from twelve to fifteen glan-
dular bodies, divided in the foetus, and in some quadrupeds, attached to
the posterior part of the abdomen, behind the peritoneum, are surround-
ed with a cellular covering of different thickness, and particularly remark-
able by the consistence, approaching to that of tallow, of the fat which
fills its cells.

If ever the art of man shall penetrate into the mystery of the intimate
structure of our organs, it seems probable that the kidneys will furnish
the first solution of the problem*. Even coarse injections pass readily

the prussiate is injected, it can be detected in the blood by means of re-agents ; but
when the quantity is small, it is impossible to discover its presence by any of the usual
tests. 3. That the same thing takes place if the prussiate be mixed with blood in a
vessel. 4. That this salt may be detected in the urine in any proportion, and therefore
it is by no means extraordinary, that DARWIW and BRAJTIJE could not find in the blood
a substance which they easily perceived in the urine. Mag. Phys. Vol. II. p. 380.

The existence of absorbent vessels which open into veins along their smaller ramifi-
cations, and even towards their terminations, and the frequent anastomoses of the form-
er set of vessels with the latter, all which appears to be satisfactorily shown, (See AP-
PENDIX, Note Q.) sufficiently explain the rapid transit of liquids, or other substances,
from the stomach and other parts of the bo6y into the circulating fluid, and their quick,
but subsequent, appearance in the secretions,

In consequence of the activity of those secreting organs whose chief function it is to
remove substances from the blood, which would become deleterious from their accu-
mulation in it, and owing to the stimulus which such substances give these organs when
conveyed to them in the course of the circulation, they are eliminated from the blood
as last as they enter it, so that they seldom can be present in sufficient quantity to be
detected by the usual chemical agents. Copland.

* One of the latest and most minute dissections of the kidney, has been made by
EYSENHABDT, of Berlin, (De structura renum Observationes Anatomies, Ber. 1818,
4to. His observations were made on very thin slices of the kidney cut longitudinally,
and also in the short diametet : these were wetted with diluted alcohol, and examined
in the microscope. •« The experiments were originally made to discover the peculi-
arity, it any, of a diabetic kidnev; but no perceptible difference was found to exist be-
tween the diabetic and healthy sttte of this organ.

« The naked eye discovered sm*i p0mts On these slices, which the microscope re-
psesented as oval and sometimes rtnnd granulations, situated at different distances
from each other, and varying in size, i^th in the same kidney and in the kidneys of
different sexes. After maceration, thesx g^n9 couid be detached with their adher-
ing vessels, and a void was left. They wye composed of knotty vessels, surrounded
by an ash-grey substance, and united, not j*, much by frequent anastomoses, as by
numerous meetings with each other. The a^.coloured substance was not granular;
it appeared as if traced with * pencil. Injectio, by the renal artery made these cor-
puscules wholly red ; but still, some deeper and e\her clearer points could be perceiv-
ed in them. Dr. E. considered these corpuscules u be the glandules and glomerules
of MALPIGHI and of SCHUMLANSKY. He could not tnce the veins arising from these
glandules ; but he refers to an observation of PIIOCHASCR<, in which a successful injec-
tion of the renal vein showed, under the microscope, a \<?.ry loose, vascular little net,
surrounding the isolated corpuscules of the cortical substanc< " Dr. Mapes, of Frank-

115

from the renal arteries into the ureters, or excretory ducts of the kid-
neys ; a convincing proof of immediate communication among theminute
arteries, which exceedingly tortuous form, with the minute veins, the
cortical or outward substance of the kidneys, and the straight urinaey
tubes, which distributed in conical fasiculi, in the interior of these or-
gans, constitute what has been called its tubuli and papillae. The passage
of injections from the arteries into the renal veins, is as easy ; and I have
often seen the coarsest liquids flowing at once by the ureters and by the
emulgent veins. This free communication between the arteries, the
veins, and excretory ducts of the kidneys, gives an idea of the ra-
pidity with which the blood must flow through these organs, whose
firm consistence allows a very moderate dilatation io the vessels ; and
suggests the possibility of a sort of filtration of the urinary fluid, the se-
cretion of which would be only succession of chemical or mechanical se-
parations, from the blood, in its passage along very minute ducts, of a
bore progressively decreasing. This was the opinion, at least, of Ruysch,
whose system on the intimate composition of our organs, and on the im-
mediate continuation of the blood-vessels with the excretory ducts is
chiefly founded on the facts of structure, discovered to him by his beauti-
ful injections of the renal arteries.

The kidneys are of duller sensibility, and less energetic action than the
other glands. The force of life has less to do in their secretion, and their
functions may be more readily explained on the principles of chemistry
or hydraulics.

XXXIII. If we attempt, indeed, to apply to the urinary organs the
fundamental laws on the mechanism of secretions*, it is not seen, that
these organs are not under their absolute controul. Of all the animal
fluids, urine is the one most complex in its elements, and most variable in
its qualities. Not only do foreign substances- sometimes appear in it, af-
feet, and even change its composition; other fluids may, at times* J*ix
with it, and disguise it altogether. Thus credible observers tells us
appearance of urine, of bile, fat, milk, blood, pus* of which m^v
may be found collected in Mailer's great work on physiology, The kid-
neys, then, have less sensibility than the other secretory organs : they
reason less, if I may venture on the expression, on these^at^onPro^uced
by the various substances in the blood : their action^ also less power-
•j» Z. .

fort on the Maine, says, that he has seen exactly this st^ct.ure.. from injections of the
hepatic vein, and therefore he infers that the anatonv ot tne Ilver and kidney may be
similar in other respects.

From these glandules, EYSENUARBT says' " t^1 tne g^yish and transparent urini-
ferous vessels, which seem to be articulated, *'lse- Tnese vessels form a net-work,
which every where unites the glandules witb~ach other- He therefore thinks SCHUM-
I.ANSKT was deceived, in supposing that -ach glandule had a secretory duct, which,
after making numerous curves, ran strait into the medullary substance.

" Little precise information is give* b7 EITSENHABDT respecting the medullary part.
The excretory ducts, however, whir1 "become straight when they pass out of the corti-
cal substance, pass along in fascic^1 °f about twenty in each fasciculus.

" In a foetus, the cortical substance was smaller in proportion, and the glandules were
of scarcely half the size. Eac* vascular vessel of the medullary substance was com-
posed of granulations ; some°f them being voluminous, and others much smaller, and
all strongly pressed against each other, so that the vessels could no longer be distin-
guished from each other, but their passage only marked by striae. The granules were
not produced by putrefaction, although putrefaction gives a globular appearance to
these parts." — Copland.

* See the Chapter on Secretion*

116

ful ; it does not so intimately affect the fluid subjected to it. It does not
change the heterogeneous qualities of those that are mixed with it, and
allows them to pass in a pure state*.

This multitude of elements in the composition of urine, had surely
been understood by the ancients, before it was demonstrated by modern
chemistry : ibrthey considered it as a sort of extract of animal substance,
as a real lixivium, carrying off all that is impure in the economy, and
gave it the name of lotium^ which indicates that destination.

Finally, the secretion of urine is more uniformly carried on : it is con-
tinual, or at least, does not exhibit so prominently those alterations of ac-
tion and repose, so apparent in the work of the other secretory organs.
When, in a case of retention of urine, we introduce a catheter into the
urinary bladder, and leave it there, the urine keeps dropping continually,
and would wet the patient's bed, if the orifice of the catheter were not
kept closed. In the Memoirs of the Academy of Sciences for the year
1761, there is related a case of singular conformation of the urinary
bladder. This musculo-membranous viscus protruded through an open-
ing at the lower part of the linea alba, and was turned inside out, so as to
present externally, its mucuous membrane. This case afforded an oppor-
tunity of observing the continual flow of the urine through the orifices of
the ureters, and of ascertaining the different circumstances attending this
process, either with regard to the qualities of this fluid or to the quantity
which might be voided, in a certain space of time ; and in this respect,
there was a good deal of difference, according to the state of sleep and
waking, to the quantity, and to the diuretic qualities of the drink.

The urine contained in the ureters is turbid and imperfect $ its consti-
tuent parts are not thoroughly blended together, as may be observed, if
made to flow, by compressing the kidneys in a dead body. It improves
by passing along those ducts, acquires the characteristic qualities of
ui'ne, oozes at the surface of the papillae, and flows into the membranous
c allies which embrace the rounded terminations of the tubuli uriniferi.
The uiJQt) Of the calices forms the pelvis, or the expanded portion of the
ureters, o, membranous ducts, along which the urine is incessantly flow-
ing into the 1^^^. The urine flows into the bladder by its own weight,
and especially \v tne action of the parietes of the ureters, which possess

* This opinion is very r,fferent from that entertained by Dr. THOMSON. He conceives
that it is not merely the abs,.,action o{ a quantity of water and of salts accumulated in
the blood which the kidneys p ,,forn% bm that a chemical change is produced by them,
either upon the whole blood, or t least upon some important part of it. In proof of
this additional function, he adduce. the wmat;on of nephrin and uric acid, as he sup-
poses, in the kidneys. These two ^stances," he says, « are formed in the kidneys,
and as they are thrown out, after ben,t formed, without being applied to any useful
purpose, they are certainly not formed m ve kidneys for their own sake. Some part
of the blood then must be decomposed in tlKkidnev> and anew substance, or substan-
ces, must be formed ; and the urea and uric ac^ must j-,e formed at the same time, in
consequence ot the combined action of the aflim:es whicii produce the change on the
blood ; and being useless, they are thrown out togvtner with a quantity of water and
stilts, which in all probability were useful in bringjn, about the changes which take
place in the arteries and in the kidneys, but which areno longer of any service after
these changes are brought about. Thorn. Vol. IV. p. 62.

This reasoning rests entirely on the assumption that those substances are actually
formed in the kidneys ; it is quite as probable that they are produced in other parts of
the body, and are, with other substances, removed from the blood by the action of
those organs. See APPENDIX, Note P, for some experiments and further observa-
tions in support of the latter opinion. — Copland.

117

a certain degree of contractility. To the above causes, may be added the
concussions excited by the pulsations of the renal arteries, behind which
the pelvis of the kidney is situated, and by the pulsations of the iliac ar-
teries, in front of which the ureter passes, before entering the cavity of
the pelvis ; the alternate compression from the viscera of the abdomen,
during the motions of respiration ; the concussion attending bodily exer-
cise, as riding on horseback, walking, running, Sec. ; the pressure of the
column of urine from the kidneys, and the want of resistance towards the
bladder.

XXXIV. The urine is continually passing, in drops, into the bladder,
it separates its parietes, without, however, exciting in them any percepti-
ble impression, as they are accustomed to its stimulus. The urine cannot
accumulate in the musculo-membranous cavity of the bladder*, which is
situated, exterior to the peritoneum, in the cavity of the pelvis, behind the
pubis, above which, in the adult, it never rises, except when excessively
distended, unless it is prevented from flowing along the urethra, or from
returning by the ureters. This retrograde flow is prevented by the ob-
lique insertion of these ducts, which pass, for some distance, between the
muscular and mucous coats of the bladder, before opening within it, to-
wards the posterior angles of the vesicaltrianglef, by openings of smaller
dimensions than their cavity. The inner coat of the bladder, raised over
these apertures, gives them the appearance of being provided with valves,
which fit the better these orifices, according as the urine contained in the
bladder, by separating its parietes, presses against each other the coats
by which they are formed, and between which the ureters pass, along a
space of from seven to eight lines.

The urine which flows into the bladder, requires a certain degree of
force, to separate its parietes on which the weight of the intestines press-
es. This is effected by no other power, than by that which causes the
flow of the urine along the ureters, and though inconsiderable, it will ap-
pear sufficient, if it be considered that the fluids which pass from a strait
channel into a larger cavity, act on every superficial portion of its parietes
equal to the area of the channel, with a power equal to that which deter-
mines their flow into the latter; so that if the urine descends along the
ureters, with a degree of force equal to one, and if the inner surface of
the bladder is a thousand times more extensive than the area of the ure-
ters, the power will be multiplied a thousand fold.

This purely mathematical proposition is expressed by saying, that the

* In the numerous tribe of birds, the bjfedder is wanting. In them, the ureters open
into the cloaca, a musculo-membranous bag, which supplies the place of the rectum,
bladder, and uterus, and which serves as a reservoir to the solid excrements, to the
urine, and to the eggs detached from the ovaria. The urine of birds dilutes the faces,
and furnishes the carbonate of lime which forms the basis of the egg-shell. It has such
a tendency to concretion, that 1 have always observed, in dissecting various fowls of
different kinds, an earthy, saline, or crystallized substance, forming white striae easily
seen in the fluid of the ureters, through their skin and transparent coats. Hence one
may readily conceive, how frequently calculi would form in these animals, if their
urine accumulated and remained, for any length of time, stationary in a cavity destined
to contain it Jluthor's Note.

| The French anatomists give the name of trigone -vesicae, to that portion of the
bladder, included between the openings of the ureters and the neck of the bladder,
and forming a triangle, whose base is represented by a line drawn from the opening of
one ureter to the other, and whose apex is situated at the insertion of the urethra into
the neck of the bladder. — Translator.

113

force with which the urine passes along the ureters, is to that by whicis
the parietes of the bladder are distended, as the calibre of the ureters is to
the superficies of the bladder.

The pressure which the urine, accumulated within the bladder, exerts
on the lower part of the ureters, does not prevent the force which deter-
mines its descent along the ureters, from carrying it into the bladder: —
for, the column which descends along the ureters, being higher than that
contained in the bladder, these two organs represent an inverted syphon,
the longer branch of which is represented by the ureter.

The following are the causes which enable the bladder to retain the
urine: the contraction of its sphincter, a muscular ring surrounding the
termination of the urethra into the bladder: the angle formed by that
canal, after it leaves the bladder; and lastly, the action of the anterior
fibres of the levator ani, which surround the neck of that organ, surround-
ed besides and supported by the prostate gland. These fibres, which
are calculated to compress the prostate over the neck of the bladder, and
to raise the latter against the pubis, have been called by Morgagni, fisettdo
sphincteres vesicse.

The urine, deposited by drops into the bladder, gradually separates its
parietes. This musculo-membranous organ rises, and at the same time,
carries upwards the convolutions of the ileum, and the peritoneum before
which it lies, behind the pubis and the recti muscles with which it is in
immediate contact. These relations of the peritoneum to the distended
bladder, account for the possibility of puncturing it above the pubis, so
as to let out an accumulation of urine, without penetrating into the cavi-
ty of the peritoneum. The urine remains a certain time in the bladder,
according to the capacity of the latter, to the irritability and extensibility
of its parietes, and according to the acrid or stimulating qualities of the
fluid itself. Thus in old men, in whom the bladder has but a small de-
gree of irritability and contractility, the urine is voided less frequently;
it accumulates in greater quantity, and is, at times, evacuated with diffi-
culty. The use of diuretics, especially of cantharides, renders the urine
more stimulating, it excites powerfully the parietes of the bladder, and
incessantly stimulates it to contraction. Every cause of irritation seated
within the bladder itself, or in its vicinity, renders more frequent the
calls to void urine. This is observed in cases of stone in the bladder, of
piles, gonorrhsea, See. The urine, while in the bladder, becomes thicker
from the absorption of its more fluid parts, its elements become more
intimately blended, sometimes even, it appears to undergo a certain de-
gree of decomposition.

XXXV. When, either by the extension which the urine occasions in
the muscular fibres of the bladder, or by the irritation which it excites
in the nerves distributed on its inner membrane, we experience in the
pelvis a sensation of weight, together with a kind of tenesmus, which, as
it extends along the urethra, warns us to void urine; then we bring on a
contraction of the bladder, and joining to its action, that of the abdomi-
nal muscles and of the diaphragm, .we expel the urine by a process very
similar to that of the excretion of the faeces, (XXIX.) It should be ob-
served, however, that in a healthy state of the parts, this assistance is
required, only to overcome the equilibrium between the contractions of
the bladder, and the resistance which the cause of retention opposes to
the evacuation of the urine. After the simultaneous contraction of the
diaphragm and abdominal muscles, to press down the intestines on the

119

bladder, and to determine the first flow of the urine, \ve cease that effort,
and the bladder alone, still supported by the weight of the surrounding
viscera, which compress it as it empties itself, completes the evacua-
tion. We repeat the first effort, only in case we wish to accelerate the
flow of the urine. In the evacuation of the faeces, on the contrary, the
muscular coat of the rectum requires the incessant co-operation of the
respiratory powers, as these solid substances are evacuated with more
effort than the urine. To prove, beyond a doubt, that the urine is evacu-
ated, chiefly by the action of the bladder, OTIC need but observe the violent,
but useless straining of patients affected with retention of urine, from pa-
ralysis of the bladder*.

The urine is projected along the urethra with the greater force, as it
passes from a spacious cavity, into a straight canal, and it is expelled with
a force proportioned to that of the muscular coat of the bladder: we know,
that in old men, this is so weak, that the jet of urine is not projected more
than a few inches beyond the urethra. The urethra is not to be consider-
ed as inert in the evacuation of the urine, it closes upon it and acceler-
ates its flow, aided in that action, by the bulbo-cavernous muscles to
which several anatomists have given a name taken from their functions,
(acceleratores urinas.)

The action of these muscles expels the last drops of urine which remain
within the urethra, when the bladder is completely emptied. The con-
tractile and tonic action of the urethra is so distinctly marked, that its
spasmodic contraction may be enumerated, among the causes which fre-
quently occasion a difficulty in introducing the catheter. If we attempt
to inject fluids along the urethra the moment we remove the pipe of the
syringe which closes its external orifice, that instant, theparietes of the
canal contract on the fluid, and expel it with a rapid jet.

The bladder and the canal of the urethra are lined internally with a
membrane, whose mucous follicles secrete a viscid humour calculated to
protect the parietes of these organs, against the action of the urine, and to
facilitate the evacuation of that fluid. This membrane, whose surface is
more extensive than the cavities which it lines, forms a great number of
folds, which disappear when the bladder is distended with urine. This
mucus is secreted, in an unusual quantity, in catarahal affections of the
bladder, and becomes, likewise, more ropy and more albuminous. The
mucous secretion of the glands of the urethrais altered in its quality, and
becomes more abundant, from the action of the venereal poison, and gives
rise to the discharge of gonorrhaea; the orifices of these lacunae may
stop the end of a catheter, so as to add to the difficulty of introducing
that instrumentf.

* It is scarcely credible that^some physiologists should have considered this organ as
inert and absolutely passive, in the evacuation of urine, which, in their opinion, is per-
formed by the immediate pressure of the abdominal muscles and diaphragm on that
cavity. Amid this variety of opinions, if you wish to come at the truth, you must take
a medium. Iliacos intra muros peccatur, et extrfi — Author's Note.

f When this operation is performed in a case of simple paralysis of the bladder, it is
better to employ a very large catheter, which may stretch the parietes of the urethra,
and prevent their forming into wrinkles, and whose rounded beak may not get engaged
in the lacunae of that canal.

When in a case of retention of urine, the bladder rises above the pubis, its bas fond
is .earned upwards, and there is a period of excessive distension, at which, like the ute-
rus in an advanced state of pregnancy, it seems to make an effort to rise above the brim

* I ;?^ IR

The urine cannot be voided at the same time as the faeces, when these?
by their hardness, compress the prostatic and the membranous part of the
urethra, situated before the lower extremity of the rectum. It is diffi-
cult, and often impossible, to void urine during; a violent erection, as the
parietes of the canal are then closely applied to each other, by the tur-
gescence of the corpus spungiosum and of the corpora cavernosa of the
penis. The mode of sensibility of the urethra, is besides changed in
such a manner, that it is calculated to permit only the emission of the
seminal fluid.

When the bladder is completely emptied, it sinks behind the pubis ;
the tumour which it formed above these bones, while in a state of dis-
tension, collapses, the abdomen becomes less prominent, respiration more
free, and there is a general feeling of lightness. The bladder cannot be
completely evacuated, unless the pelvis is gently inclined forward ; its
has fond) which is on a lower level than its neck, would, in any other
posture, retain a certain quantity of urine.

XXXVI. Of the physical jiro/ierties of Urine. As this fluid varies in
quantity in a healthy man, according to the quantity and diuretic quali-
ties of the drink, the state of sleep or waking, the condition of the se-
cretions, arid especially of the perspiration, it is very difficult to deter-
mine, accurately, its proportions. Nothing varies more than its quantity,
as may be ascertained, by comparing the different calculations on that
subject, of a great number of physiologists. At times, the urine is less
in quantity than the drink that has been taken in, at others, more. It
may be affirmed, however, that the quantity of urine voided in twenty-
four hours, is equal to that of the insensible perspiration in the same time,
and it may, therefore, be estimated at between three and four pounds, in
a healthy adult. Its colour varies, from a light lemon yellow, to an or-
ange, approaching to red. Its smell and flavour are peculiar, and dis-
tinguish it from every other animal fluid. Its colour is, in general, dark-
er, its smell and flavour stronger and more pungent, as it is less in quan-
tity, as the circulatory system is more active and powerful, and as the
substances of our food are more animalized. We all know how fetid and
how scanty is the urine of carnivorous animals; how offensive to the
smell is that of the cat ! The specific gravity of urine is greater than
that of distilled water, and varies, according to the quantity of saline
and other substances, which it holds in solution : it is, likewise, slightly
viscid, but not ropy like the serum of the blood, the bile, the saliva, and
other albuminous fluids.

XXXVII. Of the chemical properties of Urine*. The peculiar qualities
of urine are always more marked in a powerful and adult male, than in
children, women, and weakly persons. By chemical analysis, the urine
is found to contain eleven substances, dissolved in a considerable quan-
tity of water, viz. urea, a gelatinous animal master, muriates and phos-
phates of soda and ammonia, in separate or in triple salts, phosphate of
lime, phosphate of magnesia, phosphorus, uric and benzoic acids. Be-
sides these substances which are constantly found in human urine, this
fluid may contain a great number of others; and if it be true that the

of the pelvis : under such circumstances in women, it is impossible to introduce the
catheter, except by increasing the curve of the instrument. — faithor's Note.

* For some observations on the physical and chemical properties of urine, see AP-
PENDIX, Note P.

tai

vriiary system is to be considered as the emunctory of the whole econo-
my, one would expect to find in it, in certain proportions and under dif-
ferent circumstances, the whole of the constituent principles which ana-
lysis has hitherto discovered in our solids and liquids. Hence, douhtless,
the difference in the results obtained by the chemists who have investi-
gated the nature of the urine, by allowing it to run into decomposition, or
by applying to it various re-agents.

As the urine is, of all our fluids, that which has the greatest tendency
to putrefaction, it should be examined shortly after being voided; it is
then distinctly acid, but in a very short time, and especially if the heat of
the atmosphere promotes and accelerates these changes, it becomes tur-
bid, its component parts separate and form various precipitates. Urea
and gelatine, which alone of its constituent principles are capable offer-
mentation and decomposition, give out ammonia, acetous and carbonic
acids, and from the chemical attraction between these newly formed sub-
stances, and from the primitive elements, there are produced new com-
pounds, the knowledge of which is of the department of chemistry.

Of all the constituent parts of urine, the most essential is a substance
of the consistence of syrup, deliquescent, susceptible of crystallization,
to which M. Fourcroy has given the name of urea. This substance to
which the urine owes its characteristic properties, its peculiar colour,
smell, and flavour, which was imperfectly known to several chemists who
had sketched some of its features, giving it different names, according to
the notions they entertained of its nature, was never well understood till
the late investigations of this celebrated professor*. It is a compound
in which azote prevails, as is shown by the immense quantity of carbo-
nate of ammonia, which it gives out in distillation; it may be considered
as the most animalized product, having such a tendency to the putrid
fermentation, that, even while in the animal economy, it is liable to
that decomposition, and might overcome the antiseptic influence of the
vital power, if nature did not get rid of it by the evacuation of the urine.

Sufficient attention has not hitherto been paid to the symptoms of uri-
nary fever, an affection occasioned by the protracted retention of the
urine within the bladder. I have observed, on several occasions, that
no kind of fever is attended with more marked signs of what physicians
term putridity. The urinous and ammoniacal smell exhaled from the
body of the patients, the yellowish and oily moisture of their skin, the
parching thirst with which they are tormented, the dryness and redness
of their tongue and throat, their frequent and irritable pulse, combined
with a flaccid and doughy feel of the cellular tissue, every thing indicates
that the animal frame is threatened with the most speedy and dangerous
decomposition.

I observed similar appearances in a cat and in a rabbit, in which I
tied the ureters. Nothing is easier than to find the ureters, and to per-
form this experiment. After a crucial incision of the parit tes of the
abdomen, on the left side, the intestines are pushed aside to the left, so
-as to apply a ligature on the right ureter, they are then pushed to the
right, while the left ureter is tied. Both ureters are seen through the
peritoneum, situated behind that membrane, in the lumber region. When
the ligatures have been applied to the ureters about their middle, the di-

* See his work entillcd. System* des Connoissances CJu^ques. 8vo. torn, X. page
753.

Q

122

vided edges of the abdomen are brought together and united by sutures,
and the body of the animal is wrapped round with a cloak soaked in some
emollient decoction. At the end of six and thirty hours, the animals be-
came exceedingly thirsty and restless, their eyes glistening; their saliva,
which flowed copiously, exhaled a smell evidently urinous: on the third
day, the cat was seized with vomiting of a slimy substance, remarkable
by its having the same smell. This convulsive agitation was followed by
an excessive prostration of strength; it died on the fifth day; the intes-
tines were not inflamed, the bladder quite empty, the ureters distended
with urine between the ligatures and the kidneys, and as large as the ring
finger. The kidneys themselves, gorged with urine, were turgid, soften-
ed, arid as if macerated. All the organs, all the fluids, the blood itself,
partook of this urinous diathesis ;*putrefaction came on immediately after
death, and at the end of a few days, an almost complete decomposition of
the body had taken place. In the rabbit the symptoms were less violent
and rapid ; it did not die till the seventh day ; the smell of its whole body,
though evidently urinous, was less offensive, and the putrefaction which
succeeded was less rapid.

These two experiments confirm, in the first instance, what some au-
thors have said of the absence of urine in the bladder, when the ureters
have been tied, an undeniable proof that these are the only channels
which convey the urine into the bladder ; they likewise concur in afford-
ing the most convincing proof, that the kidneys are the emunctories by
means of which the blood clears itself of that part of it which is ani-
malized in excess; finally, they prove, that the retention of this fluid is
the more dangerous to the animal economy, as the urine itself is more
animalized.

Has nature the means of supplying the evacuation of urine by other
excretions ? might this highly recrementitious fluid be, without danger,
evacuated by other emunctories? With a view to answer this interest-
ing question, the kidneys have been extirpated in dogs. The removal of
one kidney, did not prevent the secretion from being carried on; in every
case in which both kidneys were removed at once, the animal died in a
few days, and on opening the body, there was uniformly found, a con-
siderable quantity of bile in the gall-bladder, in the small intestines, and
even in the stomach, as if the urea had endeavoured to make its escape
in that direction, by combining with the bile. These experiments were
performed at the Hopital Saint Louis, in the course of the year 1803.

Urea, combined with a certain quantity of oxygen, appears to form an
acid peculiar to human urine, and which is the substance of the greater
numbers of urinary calculi. It resembles urea, in this, that its crystals,
exposed to heat, give out carbonate of ammonia 5 but it differs essentially
from it, by its ready concrescibility. It, in fact, crystallizes, every time
the urine grows cold, and forms the greatest part of the urinary sediment.
This acid, so weak that several chemists have considered it to be a mere
oxide, has been called by M. M. Fourcroy and Vanquelin, the uric acid.
Among its distinguishing characters, may be mentioned its being insolu-
ble in cold water; it is so fixed, that several thousand times its own
weight of boiling water is required to dissolve it, hence it may be easy to
account for h.s so frequently giving rise to urinary calculi : we may, in-
deed, wonder that this complaint is not of more frequent occurrence,
since a slight cooling Of the urine is sufficient to cause a precipitation
and crystallization of the urine. Thus, every time an extraneous sub-

123

stance drops into the bladder, it becomes the nucleus of a calculus, form-
ed by the uric acid becoming concrete on the surface of this body, which
is of a colder temperature. Quadrupeds are less frequently affected with
urinary calculi, from the absence of the uric acid in their urine, and be-
cause carbonate of lime, of which, in those animals, such concretions are
formed, is a salt decomposed with effervescence by the weaker acids, and
several such acids are found in the urine.

Phosphorus, which may be considered as the result of a high degree
of animalization, enters, in considerable proportions, into human urine.
Besides the phosphoric salts which it contains, there is always found a
certain quantity of disengaged phosphoric acid, which holds in solution
the calcareous phosphate, ami {jives to the urine its manifest acidity, when
examined fresh, or shortly after it has been voided. It was from urine,
that phosphorus was first obtained by those who originally dUrovered it,
and from that fluid, it has long been procured for the purposes of com-
merce. But it is seldom obtained from urine, since the discovery of the
phosphoric acid in the earth of bones, has rendered the manufacture of
phosphorus easier and less expensive. In the urine of frugivorous mam-
raiferous animals, phosphoric salts have their place supplied by calcare-
ous carbonate.

Certain substances impregnate the urine with a peculiar odour. It is
well known that if one remain a few minutes in a room newly painted
with oil of turpentine, the urine, for some time afterwards gives out a
smell of violets; asparagus gives to the urine- a very remarkable fetor.

XXXVIII. Besides the accidental varieties observed in the urine, vari-
eties which cannot be determined, since the urine is never uniformly tfce,
same in its composition, and does not contain the same ingredients in the
same person, at different times of the day, according to the quantity and
quality of the food and drink, the exercise which has been taken, the af-
fections of the mind which have been experienced, &c.; it constantly
varies, according to the time which has elapsed since a meal, the age of
the subject, and the diseases under which he may labour.

Physiologists have for a long while, admitted two and even three dif-
ferent kinds of urine, according to the time at which it is voided; they
are distinguished by the names of urine of the drink, urine of the chyle,
and urine of the blood. The first is a limpid and nearly colourless fluid,
•which frequently retains, in a remarkable manner, the qualities of the
drink, and is voided shortly after drinking, and has scarcely one of the
characters of perfect urine. The urine of the chyle or of digestion,
voided two or three hours after a meal, is more formed, still it is not per-
fect, and does not contain all the component parts of this fluid.

Lastly, the urine of the blood which is voided seven or eight hours after
a meal, and in the morning after the night's- rest, contains, in an eminent
degree, all the qualities of urine, hence it is that which chemists prefer
using in their analysis. The imperfect state of the two former kinds of
urine, would prove better than the rapidity of their secretion, the disputed
existence of a peculiar communication from the stomach and intestines
into the bladder.

The urine of children and that of nurses contains very little phosphate
of lime and phosphoric acid ; it is only after the process of ossification is
completed, that these elements abound in the urine. That of old men,
on the other hand, contains a considerable quantity of these substances $
their osseous system already containing phosphate of lime in excess, and

124

incapable of receiving more, this saline substance would ossify all the tis-
sues, as it sometimes does that of the arteries, the ligaments, the carti-
lages and membranes, if the urine did not carry off the greater part.

In the rickets, it is by the urine that the phosphate, of lime is carried
out of the system, and the absence of that substance is the cause of molli-
ties ossium $ on the approach of fits of the gout, the phosphoric ingredi-
ents of the urine diminish, and seem to be carried to the joints, to pro-
duce in their vicinity arthritic concretions.

The great quantity of saline and crystallizable elements which enter
into human urine, accounts for the frequency of the concretions which
form in that fluid. Urinary calculi were long considered as formed of a
single substance, which the ancients thought analogous to the earth of
the bones, and which Schf^1^ *<^K for uric acid. The late investigations
of M. M- Fowi uroy and Vanquelin have shown, that the component parts
of urine are too numerous and too complex to produce uniformly calculi
of one kind : that urinary concretions, most frequently formed from uric
acid, contain urate of ammonia, phosphate of lime, phosphate of ammo-
nia and magnesia, oxalate of lime, silex, and that these substances, singly,
or in binary and ternary combinations, form the materials of nearly six
hundred calculi which they analysed. Notwithstanding the extent of
these researches, there is reason to believe, that when carried further by
the same chemists, they will be attended with results still more varied.
For, as there is no integral molecule in the body which may not be voided
with the urine, and be found in the urine, so it is conceivable, that under
certain circumstances, which it is impossible to assign or to forsee, every
tjilng in the human body that is capable of concretion, might supply the
materials of urinary concretions.

This variety of elements in the composition of urinary calculi, the ab-
sence of signs, by which to ascertain their nature, the sensibility of the
parietes of the bladder which would be irritated by agents capable of dis-
solving the concretions( so frequently formed in its cavity, must render it
very difficult, not to say impossible, to discover a lithontriptic which
should supersede the necessity of a surgical operation, whose difficulties
and danger have been much over-rated.

XXXIX. The energy of the urinary system in the inhabitants of tem-
perate climates, has been considered as the cause of the frequency of cal-
culous affections in Holland, England, and France, while they are very
rare in more southern countries, in which the cutaneous perspiration
seems to be substituted, in great measure, fyr the urinary secretion.
There is no part of the world in which cases of stone in the bladder are
more frequent than in England, and especially i» Holland, in which a cold
und damp atmosphere is unfavourable to perspiration, which is, at any
rate, but scanty in persons of a leucophlegmatic temperament like that of
the Dutch. In no other country, could a lithotnist (Raw) have operated
on more than fifteen hundred patients, it is said, successfully. Diabetes,
or an immoderate discharge of urine, a disease ivhich appears to depend
on an excessive relaxation of the renal tissue, js of frequent occurrence
only in cold and damp countries, as Holland, England, and Scotland; it is
more rare in France and Germany, and is unknown in warm climates.
This relaxation of the renal tissue in diabetes, depends on the exhaustion
of the urinary organs called into too frequent action, as is proved by the
efficacy of tonics and astringents in the treatment of that complaint.

Cutaneous affections, on the contrary, seem to belong to the inhabitants

125

of southern countries*. Lepra originated in Judea; the elephantiasis
rubra of Cayenne, the framboesia of Java, the yaws, elephantiasis, her-
petic and psoric eruptions, are more frequent among the inhabitants of
southern latitudes than among those who live under the temperate zones.
In countries near to the equator, the surface of the body, habitually ex-
posed to an ardent atmosphere, is powerfully excited : the skin is irrita-
ted, and its secretion increased; perspiration becomes so profuse, thatit
weakens, in a short time, those who, coming from distant countries, are
not accustomed to so intense a heat. The activity of the cutaneous sys-
tem exceeds that of the urinary system, whose action decreases in propor-
tion. These differences in the energy of the two systems, account readily
for the difference of their diseases: for, it is a law of Nature, that the
more an organ, or system of organs, is called into action, the more it is
liable to disease, which is but a derangement of its action.

Calculous affections are more frequent in children and old people than
in adults. In old age, the proportionate quantity of the urine exceeds
that of the perspiration. Phosphoric salts, the base of a great number
of urinany calculi, are more abundant in old men, as is proved in them by
the ossification of the arteries, of the ligaments, of the cartilages, of the
membranes, ihe solidification, ar.d the almost universal induration of the
different parts. In children the activity of the urinary system is propor-
tionate to that of the digestive organs. Destined to throw out the resi-
due of nutrition, which, at that period, is very active, the organs by
which the urine is secreted are likewise endowed with considerable ener-
gy. Lastly, it is observed, that the greatest number of calculous patients
received into the hospitals of large towns, come from low and damp
streets near to rivers; every thing-, therefoie, tends evidently to esta-
blish, that the frequency of urinary calculi, depends on an increase of
activity, in the organs destined to the secretion and excretion of urine.

CHAPTER II.

OF ABSORPTION.

XL. IN the history of the phenomena of life, a statement of the func-
tions of the absorbent system, ought immediately to follow that of the
functions of the digestive organs. The vessels, which take up the chyle
separated from the food, by the action of the organs of digestion, form a
considerable part of the absorbent system, bear a perfect resemblance to
the other lymphatics, and differ from them only in their origin. When
digestion is not going on, those vessels convey lymph absorbed in the in-
testinal canal, the inner part of which, even when in a state of emptiness,
is always bedewed by an abundant quantity of serous mucus.

* It would be more correct to say that cutaneous affections are more frequent among
the inhabitants of southern climates.

126

. There exists in all the parts of the human body, in the interior, as well
as on the surface of our organs, vessels whose office it is to absorb, and
to carry into the mass of the blood, those substances by which our ma-
chine is maintained and kept in repair, as well as what comes off in the
continual destruction of our parts; for, it must not be forgotten, that the
organized and living machine, inwardly acted upon by a double impulse,
is perpetually undergoing decay and renovation.

XLI. Absorption is effected on substances introduced from without ;
such is the absorption from the skin, and the absorption of the chyle,
&c. At other times, absorption takes place in fluids effused by arterial
transudation ; such is the serosity which moistens the serous membranes,
the fat, the marrow of the bones, and this absorption, almost always,
bears a proportion to transudation, so that the serosity, absorbed as fast
as it is effused on the surface of the membranes which lie in close con-
tact, except in cases of dropsy, never accumulates so as to separate
those membranes. Finally, there is a kind of absorption, which may be
termed nutritive or molecular, because it exerts its influence on mole-
cules, which, in the process of nutrition, are separated from the organs,
and replaced by others. It is this absorption which brings about the de-
composition of organs, and to which John Hunter gave the name of in-
terstitial absorption. By means of it, the thymus, so voluminous in the
foetus, disappears entirely in the adult. This absorption seems to be in-
cessantly going on, and to carry on decomposition, with a force that can-
not be resisted. It explains in a satisfactory manner, the spontaneous
erosions of the living solids, of which ulceration* is the consequence.
M. Dumas has endeavoured to explain in this way, the sensation of hun-
ger, which, in the opinion of that physician, is felt when the absorbents
exert on the solid coats of the stomach, their activity previously employ-
ed in taking up liquids. But to give even a degree of probability to that
supposition which is entirely gratuitous, it would be necessary to show,
that the parietes of the stomach have been found destroyed or thinned, in
persons who have died of hunger. The parietes of the stomach of such
perspns, have, on the contrary, been found thickened and in a state of
contraction. This inward absorption is promoted by inflammation, hence
the advantage of applying heat to indolent tumours, and of exciting a
slight inflammation in swollen glands, in order to bring about resolution.
It is on that account, that in swelling and induration of the testicle, unat-
tended by cancer of the part, the operation for hydrocele by injection,
may be safely employed. — Of this I had a convincing proof, a few years
ago; a gardener, born deaf and dumb, had for some years an hydro-
cele, which he was in the habit of getting tapped every six months.
When I last tapped it, I found the testicles swollen and hard, and three
times larger than in its natural state ; the patient, however, was free
from pain. A considerable quantity of a reddish serous fluid was dis-
charged; at the end of two days, inflammation of the tunica vaginalis
came on, the scrotum became enlarged, and was covered with emollient,
poultices. At the end of twenty days, the testicle was a good deal lessen-
ed in size, and adhered to the inside of the tunica vaginalis : the cure
was considered radical, and proved such; for, though it is now ten years
since the operation was performed, the water has not collected, and the
patient continues in the laborious employment of his business. I frequent-

* NosograpUe Chirurgicale tome 1. art. Ulceres ^tomques.

127

ly meet him, and he never fails, by inarticulate sounds and signs of satis-
faction, to express to me his gratitude.

The processof absorption is very active in children, in women, during
sleep, in the morning, when the body is refreshed by the night's rest. Is
a state of weakness favourable or unfavourable to that process ? it is well
known, that there are robust men who have intercourse with women in-
fected with the venereal virus, and who escape the contagion, unless they
expose themselves to it, when debilitated by excesses. A mind free of
fear and anxiety, has ever been considered in the Eastern countries, a
safe-guard against the plague. A dog, caeteris paribus, is in much less
danger from the bite of a viper, when suddenly bitten, than when he has
been sometimes gazing at the reptile, and, more or less terrified by the
sight. But in all these cases, does debility favour the introduction of the
contagious matter, by increasing theforce of absorption; or is it not more
probable, that by affecting the nervous system, it renders it more suscep-
tible of deleterious impressions* ?

XLIL Absorption is much less active, on the external surface of the
body, than on the surface of its internal cavities, and in the very substance
of our organs. Cutaneous absorption, under certain circumstances, has
even so little activity, as to have led some physiologists to doubt its exist-
ence. The absorbing orifices of vessels which arise on the surface of
the body, are covered by the epidermis. This covering, which is insen-
sible, and, as it were, inorganic, forms a sort of separation between the
external and internal part of our being, and opposes, or renders more dif-
ficult, the absorption of substances in immediate contact with our body,
and if it be considered, that we are frequently immersed in the midst of
gases and other substances, to a certain degree, deleterious, it will be un-
derstood, hov/ essential it was, that the absorbing surface of the skin,
should not be entirely exposed, and that cutaneous absorption should not
be easily carried on.

The increased weight of the body, after exercise in wet weather; the
abundant secretion of urine, after remaining long in the bath; the mani-
fest enlargement of the glands of the groin, after keeping the feet im-
mersed for a considerable time^in water, an experiment often performed
by Mascagni on himself t; the effects pf mercurial frictions, Sec. show,

* The latter is undoubtedly the explanation.

f It is now more than twenty years since the subject of cuticular absorption first en-
gaged the attention of the medical men of Philadelphia, during1 which time, it has been
prosecuted with an ardour and success hig-hly honourable to those concerned- in the in-
quiry. As early as the year 1800, it was shown, or at least rendered highly probable
by Dr. Rousseau, that the pulmonary organs, and not the skin, constitute the avenue
through which certain substances enter the system. By cutting; oft' all communication
with the lungs, which he easily effected by breathing through a tube protruded into the
external atmosphere, lie ibund that though the surface of his body were bathed with
the juice of garlic or the spirits of turpentine, none of the qualities of these fluids could
be detected, either in the urine, or serum of the blood. Conducted nearly on the same
principle, but with a greater diversity of substances, experiments exceedingly well de-
vised and ably executed, have since been made, by persons of opposite prepossessions,
to an almost incredible extent. Contradictory as many of these are, a candid examina-
tion of the whole will still lead to a pretty satisfactory conviction, that absorption from
the surface of the human body does not exist as a natural and ordinary function.

Borne down by the weight of evidence against them, most of the" advocates of the
ancient hypothesis were indeed prepared to abandon it, as no longer tenable, when
about two years n£o an experiment made by Dr. Massy, again revived their faith in cuti-
cular absorption. This experimentalist very clearly proved that if the body be immer?-

128

however, in an unquestionable manner, that absorption takes place through
the skin, with more or less rapidity, according to circumstances. It must
be taken into account, that the means which promote cutaneous absorp-
tion, operate, at least as much, by altering the structure of the epidermis,
as by increasing the action of the absorbing orifices. In this manner
the bath appears to operate, by softening the 'texture of the epidermis :
and frictions, by displacing and raising its scales.

It is by means of frictions, that we succeed in introducing into the lym-
phatic system, medicines possessing purgative, febrifuge, sedative, or
diuretic qualities, combined with the gastric juice, or diluted in any other
liquids, for, as has been shown by the experiments performed at the Sal-
petriere, by.M. M. Dumeril and Alibert, in the name of the Philomatic
Society, the mixture with saliva or gastric juice, of the medicines which
are to be administered by friction, is not necessary to insure their absorp-
tion. Extract of opium has soothed pain, bark has checked fits of inter-
mittent fever, rhubarb has procured alvine evacuations : squills have
stimulated powerfully the action of the urinary organs, nor has the pre-
vious mixture, with gastric juice, of these substances reduced into pow-
der, seemed to increase or diminish their efficacy.

Absorption takes place quickly and readily, wherever the epidermis is
thin, habitually moist, and the skin delicate, so as to leave almost bare of
covering, the subjacent parts, as on the lips, in the inside of the mouth,

ed in a decoction of madder, the colouring1 matter of this substance will be taken in, and
may be displayed in the urine, by using any one of the alkalies as a test.

Determined, if possible, to put this long1 agitated question to rest, Dr. Rousseau, as-
sisted by his friend, Dr. Samuel B. Smith, has subsequently performed a series of ex-
periments, many of which we witnessed, with every variety of substance, mild and acrid,
volatile and fixed, nutritive, medicinal, and poisonous.

The result of these extensive researches is :

1. That of all the substances employed, madder and rhubarb are those only which
affect the urine The latter, of the two, the more readily enters the system. Neither
of these substances can be traced in any other of the secretions, or excretions, or in the
serum of the blood.

2. That the power of absorption is limited to a very small portion of the surface of
the body. The only parts indeed which seem to possess it, are the spaces between
the middle of the thigh and hip, and between the middle of the arm and shoulder. To-
pical bathing1 with a decoction of rhubarb or madder, or poultices of these substances
applied to the back, or abdomen, or sides, or shoulders, producing- no change in the
urine, &c. Equally ineffectual was the immersion of the feet and hands in a bath of the
same materials. After being1 kept in it several hours, not the slightest absorption was
afforded.

Such is the state in which this interesting- subject is at present left. Though, per-
haps, n<it absolutely decided, enough surely has been done to demonstrate that cuticu-
lar absorption rarely happens, and whenever it does, it cannot be deemed the effort of
a natural function. Covered, as is the whole surface of the body by the impervious
cuticule, it is manifest to us that absorption can only take place in one of two ways,
either by forcing the substance under the scales of the epidermis, as in the instance of
the application of frictions, or by long" continued bathing1, the cuticle becomes so chang-
ed in its organization, as to admit of transudation, or the insinuation of the fluid under
its squamous structure, so as to come in contact with the mouths of the lymphatics situ-
ated within.

At all events, whatever difference of opinion may be entertained as to the degree of
conclusiveness of the experiments to which I have alluded, it can hardly be thought ne-
cessary to resort to cuticular absorption, to explain the facts enumerated by our author
as proofs of the existence of the function. These, and, perhaps, all other phenomena,
hitherto referred to the agency of absorption by the skin, may be more rationally ac-
counted for on the principle of pulmonary absorption, and the b>v of sympathy. —
Chapman.

129

on the surface of the glands, Sec. The complete removal of the epider-
mis, favours absorption from all parts of the skin which it covered.
Hence the least scratch on the fingers of an accoucheur touching women
infected with the venereal virus, exposes him to this peculiar infection,
which, in such cases, is the more to be dreaded, from the admission of
the virus by an unusual course. The innoculation of variolous and vac-
cine matter, equally furnishes proofs of the obstacle which the epidermis
presents to cutaneous absorption, and of the facility with which that func-
tion takes place, from surfaces denuded of that covering. Absorption
goes on, likewise, with great activity, from the surfaces of internal parts,
but it no where is so considerable, as in the intestinal canal, and it would
perhaps be the most favourable part for introducing medicinal substances
into the animal economy, if when swallowed, they did not undergo changes,
by mixing with the gastric juices, or with the intestinal fluids and faecal
substances, when injected by the ?ectum. From the evacuation by urine
of clysters of warm water, soon after they have been administered, it is to
be presumed, that the great intestines absorb, almost as powerfully as the
rest of the digestive canal. A pint of warm water injected into the abdo-
men of a large dog or sheep, is often absorbed in less than an hour, and
the effusions which take place in those cavities, would possibly not re-
quire an operation to let them out, if such fluids were not subject to coa-
gulation, and if the absorbing surfaces were not diseased.

Besides absorption from surfaces, there exists, as we have already stated,
another which takes place in the living solid, and in the internal substance
of the organs. It is by this kind of absorption, that the nutritive decom-
position is effected ; by means of it, the living matter is incessantly reno-
vated. Its vitiated action accounts for the spontaneous formation of
ulcers, the disappearing of the thymus, the atrophy of parts in which nu-
trition is carried on, in a sluggish manner ; the resolution of certain
tumours, and many other phenomena, are dependent on the same cause.
I do not think, however, that it is possible to admit the explanation of the
sensation of hunger, adopted by Professor Dumas, who believes that it
depends on the action of the absorbing orifices directed against the or-
ganized substance of the stomach, in the absence of aliment on which to
act*. The sensation of hunger is felt only in the stomach, although its
effects extend to all parts of the body: it begins in a circumscribed spot,
its seat is limited, yet absorption takes place every where, so that if the
hypothesis in question had any foundation, the sensation of hunger ought
to be felt at the heel, as well as at the pit of the stomachf.

* Both hunger and thirst seem to be sensations, excited by the stomach's sympathis-
ing with the general exhaustion of the system, and are the means employed by nature
to admonish us of the necessity of repairing the wastes which it sustains from abstinence.
An office so imporsant to our well being, and even existence, is not left to reason,
which might often err, but is put under the care of an instinct, far more certain in its
operation. Besides these two sensations, the stomach has others equally specific : as
satiety, longing, loathing, sickness, &c. &c.— Chapman.

f It does not fall to the lot of every one, to err like M. Dumas, whose talents and in-
genuity I have much pleasure in acknowledging. He imagines rickets to consist, in
a deficient influence of the nervous system on the bones; which would constitute a
kind of paralysis. Anatomy shows the presence of no nerves in the tissue of thebones>
and veins and arteries are alone seen to enter the foramina, and no nerves appear
to be transmitted through them. The functions of the bones made it unnecessary that

130

The radicles from which the lymphatics arise, have orifices so very
minute, that they are imperceptible to the naked eye; a tolerably accu-
rate notion may be formed of them, by comparing them to the puncta la-
chrymalia, which are larger and more easily discovered. Each orifice
endowed with sensibility, and with a peculiar power of contraction, di-
lates or contracts, absorbs or rejects, according as it is affected by the
substances which are applied to it. The variations of the absorbing pow-
er, according to the age, the sex, the constitution, and different periods
of the day, show that it cannot be compared, as several physiologists have
clone, to that principle which makes fluids ascend, contrary to the laws
of gravitation, in capillary tubes. If absorption were a process merely
mechanical, it would, in no case, be accelerated or retarded, and would
proceed with a regularity never observed in the vital functions. The
mouth of every lymphatic, when about to absorb, erects itself, draws
towards itself, and raises the surrounding membranous parts, and thus
forms a small tubercule similar to the puncta lachrymalia. These little
bulgings deceived Lieberkuhn, and led him to think, that the absorbents
of the intestines, originated from small ampullalae, or vesicular enlarge-
ments, which, as so many exhausted receivers, pumped up the fluid ex-
tracted from the food*. This physiologist may, further, have been led

they should be endowed with that peculiar sensibility which requires the existence of
nerves. The bones are active by being subject to the process of nutrition, but in
every other respect, they are absolutely passive. In the opinion of some people, such
doctrines are real discoveries. Credat judxus Jipella,^ non ego. — Author's Note.

* As to the precise manner in which absorption is effected, physiologists are not
agreed. By some it is contended, that it is entirely the result of capillary attraction.
To the exercise of this species of affinity, three circumstances seem only to be de-
manded :

1. The tube must not exceed a certain size.

2. It must be of an equal calibre throughout.

3. One of its extremities must be immersed in a fluid.

Notwithstanding what has been urged to the contrary, capillary attraction unques-
tionably is influenced neither by the flexibility of the tube, nor its position. It is now
perfectly well ascertained, that the operation goes on whether the tube be soft or hard,
or whether it be placed vertically, horizontally, or obliquely.

These facts being admitted, and also, that the lymphatic vessels are within the di-
mensions necessary to capillary attraction, which they undoubtedly are, the hypothesis
referring absorption to this principle, does not, at first view, strike us as altogether un-
reasonable. When examined, however, more clearly, it will be found liable to all the
embarrassments enumerated in the text, and to others of not less weight.

Two additional objections at once occur to us.

1. Did the absorbents act mechanically, as is alleged, they would take up indiscri-
minately all fluids presented to their mouths, instead of which, they exercise a degree
of selection amounting almost to fastidiousness.

2. The absorbents have not that mechanism which capillary attraction requires.
They frequently swell or bulge out in their course, and become of irregular capaci-
ties. Even at their orifices they assume the figure of the funnel, commencing with an
exceedingly minute opening, which suddenly expands. Aware of the unfavourable-
ness of the structure to the progression of fluids, it has been maintained by some other
of the advocates of capillary attraction, that the fluid is simply imbibed by the power of
this principle, and afterwards propelled by the united force of muscular pressure, and
the action of the contiguous arteries.

We do not think the hypothesis at all improved by this modification of it. We be-
lieve, that in absorption there is no capillary influence, or, indeed, any sort of extrinsic
agency employed. It seems to us to be owing altogether to the inherent contractile
power of the vessel, and bears no very remote analogy to the peristaltic action of the
intestines. We will, however, in a few words, explain our meaning more distinctly.

When chyle, or any appropriate fluid, is applied to the mouth of an absorbent, it is

131

into error, by the nervous papillae of the inner membrane of the canal,
swollen by the determination of blood attending irritation, the natural
consequence of the friction of the alimentary substances. The inhaling
faculty belongs, not only to the orifices at the extremity of each radicle,
but, likewise, to the lateral pores, which are infinitely numerous, in the
parietes of the vessels*.

XLIII. After arising on the surface, and in the interior of the body,
by radicles in close contact, the lympathetics creep and coil themselves,
describe numerous curves, unite, then divide, and presently unite again,
and from these numerous inosculations, there results a net-work, with
close meshes, forming, with that of the blood-vessels, the texture of the
cellular tissue and of the membranes.

Each lamina of cellular tissue is, in the opinion of Mascagni, nothing
but a mesh- work of lymphatics — the texture^of the membranous and
transparent tissues, as the pleura and the peritoneum, resembles that of
the lamina of the cellular tissue; in fine, the same vessels form the ba-
sis of the mucous membranes which line the internal parts of the alimen-
tary canal of the trachea and urethra. The Italian anatomist succeeded
in filling, with quicksilver, all the tissues which he considered as lympha-
tic 5 but Ruysch, in his admirable injections, reduced all the membranes,
and the lamina of the adipose tissue, into a net-work purely arterial, of
which the meshes were so very closely united, as to leave spaces that
could scarcely be perceived by the microscope, and from his preparations
he inferred, the arterial capillary vessels, singularly divided and convo-
luted, form the basis of cellular and membranous tissues. To satisfy
one's self, that neither the pleura nor the peritoneum are formed as Mas-
cagni or Ruysch imagined, one need only consider, that arterial exhalation
and lymphatic absorption take place, from the whole extent of internal
surfaces, and that these two functions prove the existence of both arte-
ries and absorbents, in those membranes, and in the cellular tissue. The
prejudices of those two anatomists, so celebrated, the one by his study
of the absorbents, and the other by his beautiful injections of the most
minute arteries, are to be attributed to the importance which we are
pleased to assign to the objects which particularly engage our attention,
and likewise to the distension of the minute vessels by the injection :
these being distended beyond their natural state, compress and conceal
the neighbouring parts.

The lymphatics, after emerging from among the cellular substance,
unite into trunks sufficiently large to be distinguished from the lamina of
that tissue. These trunks proceed towards certain parts of the body,
there they become united to other trunks, follow a parallel course, and
frequently communicate together. The lymphatics are not single in their
course, as the arteries and veins; they collect together, form fasciculi of
different sizes, some of which are deep seated and accompany the blood-
vessels, while others of them are more superficial, corresponding to the
subcutaneous veins of the limbs, and, like them, lying between the skin
and the aponeuroses, and in greatest number, on the inner side of the

excited by the stimulus of the fluid to an erection ofits orifice, in consequence of which
the latter is rendered pervious. The fluid being now introduced, the vessel contracts,
and propels its contents in succession along its course to the ultimate destination.—
Chapman.
* See APPENDIX, Note Q

132

limbs, in which they arc best protected against external injuries. The
lymphatics of the parietes of the great cavities, those of the viscera
which these cavities contain, are likewise in two layers, the one super-
ficial, the other deep seated*.

The absorbents differ, likewise, from the blood-vessels, in their singu-
larly tortuous course, their frequent communications, and especially in
their unequal size in different parts of their extent. An absorbent, of very
small dimensions frequently enlarges, so as to equal in size the thoracic
duct, then contracts and again bulges out, though in the length of the ves-
sel in which these differences of size may have been noticed, it may have
received no collateral branches. The lymphatics, when completely fill-
ed with quicksilver, appear to cover the whole surface of our organs;
and the whole body seems enveloped in a net-work of close and small
meshes. The metastasi§"of humours, from one part of the body to an-
other at a distance, is easily understood by any one who has seen those
numerous inosculations, rendered manifest by injection. Metastasis
ceases to be an inexplicable phenomenon; one has no difficulty in con-
ceiving, how by means of the lymphatics all the parts of the body com-
municate freely; how, fluids absorbed by those vessels in one part, may
be conveyed into another, and pervade the whole body, without follow-
ing the circuitous route of the circulation, and that it is, therefore, not
altogether impossible, however improbable, that fluids taken into the
stomach, may be conveyed directly from the stomach to the bladder, and,
that in the same manner, the milk of the intestinal canal may find its way
into the breast; and that pus may be removed from the place in which it
is collected, and be conveyed to the place to which irritation calls it
forth. All that Bordeau has said of the oscillations and currents of hu-
mours, through the cellular texture, in his " Researches on the Mucous
Tissue," may be equally explained by the anatomosis of the lympha-
tics.

A young man whom I had ordered to rub in mercury, along the inner
part of his left leg and thigh, for the cure of a pretty large bubo, was af-
fected, on the third day, with salivation, though he used only half a dram
of ointment at each friction. The salivary glands on the left side, were
alone swollen, the left side of the tongue was covered with aphthae, and
the right side of the body remained unaffected by the mercurial action;
a clear proof, that the mercury had been carried to the mouth, along the
left side of the body, without entering into the course of the circulation,
and perhaps, without passing through any of the conglobate glands; for,
that of the left groin, which alone was swollen, did not sensibly diminish
in size. Salivation may, therefore, take place, in the cure of the vene-
real disease, though none of the mercury enter the circulation, which
warrants the opinion, that the action of syphilis, as well as of the reme-
dies which are administered for its removal, operates chiefly on the lym-
phatic system.

XLIV. If the fluids absorbed by these vessels, can, in consequence of
their numerous inosculations, pervade all parts of the body, without mix-
ing with the blood, not a drop can enter the course of the circulation,
without having previously passed through the glandular bodies that lie in
the course of the lymphatics ; dispersed like those vessels in all parts of

* See APPENDIX, Note Q, for observations on the structure, and functions of the
absorbent system.

133

*he body, seldom insulated, but in clusters in the hollows of the ham,
the arm-pit, in the bends of the groin and elbow, along the iliac vessels,
the aorta and the blood-vessds of the neck, around the base of the jaw
and of the occiput, behind the sternum, along the internal mammary
vessels, lastly, within the mesentery, in which their number and size bear
a proportion to the quantity of absorbents which pass through them.
These reddish glands* varying in size, of an oval or globular form, have
two extremities, the one at which the lymphatics enter : they are then
called " ajferentia" and the other extremity turned towards the thoracic
duct, which sends out vessels, fewer in number, but of a larger size, and
called u efftrentia" from their use.

The lymphatics, on reaching the glands, divide, unite again and inos-
culate, they likewise bend back on themselves, and thus form the tissue
of the conglobate glands, which are merely clusters of coiled vessels,
united by cellular tissue, in which blood-vessels are distributed, so as to
occasion their reddish colour. The coats of the lymphatics are thinner
in the glands than elsewhere; and their dilatations, their divisions, and
their anastomoses, are likewise more frequent, while they are in the glan-
dular tissue. All the lymphatic vessels, whose course lies in the direc-
tion of a gland, do not enter its substance, several pass by the gland and
embrace it, forming around it a sort of plexus, of which the ramifications
are directed towards other glands, more in the vicinity of the thoracic
duct. The lymphatic glands form so essential a part of the absorbent
system, they produce on the lymph such indispensable changes, that no
lymphatic vessel enters the thoracic duct, without having previously
passed through these glands. It even frequently happens, that the same
vessel passes through several glands, before opening into that common
centre of the lymphatic system. Thus, the vessels which absorb the
chyle of the intestinal tube, pass several times through the glands of the
mesentery. The lymphatics of the liver, situated very near to the re-
ceptaculum of Pecquet, have been thought, by some anatomists, not to
follow that general rale ; but there are uniformly found, in the course
of these vessels, glands which they enter. As, however, the glands are
few in number, the lymph conveyed from the liver, is only once subject-
ed to the action of the glands ; and this circumstance appears to me to
explain, in a satisfactory manner, the transmission of the colouring mat-
ter of the bile, which, in jaundice, manifestly discolours the blood, in
which M. Deyeux found it by chemical analysis.

XLV. The parietes of the lymphatic vessels are formed of two coats,
both very thin and transparent, yet very strong, since they support the
weight of a column of mercury, which would rupture the coats of arteries
of the same calibre. The internal coat, which is the thinner of the
two, forms valvular folds, arranged in pairs, like the valves of the veins,
and like them preventing a retrograde circulation. Although these coats
are very strong, and likewise very elastic and contractile, as they may
be seen to contract, and to expel the lymph with great impetus, when

* It is with a view of conforming to the language in common use, that I give the
name of gland to those coils of lymphatic vessels, which are totally cliff ere nt from the
real conglomerate or secretory glands. It might be better, perhaps, to call them^an^-
lionsy as has been done by my learned and respected colleague Chaussier, though that
name is objectionable, from its association in the mind with the nervous ganglions,
whose structure is not at all similar to that of the lymphatic ganglions. — Author's .l\"ot,\

134

the abdomen of a living animal* is laid open, yet the course of the lymph
is far from being as rapid as that of the blood; it even frequently appears
affected with irregular oscillations, such as are to be met with in the cir-
culation of the blood through the capillary arteries. The numerous di-
latations, curvatures and anastomoses of the absorbents must, in a consi-
derable degree, impede the rapid progress of the lymph, but the circula-
tion must be retarded, chiefly in the glands, as there the vessels are most
convoluted, dilated, and form the greatest number of anastomoses, and
are most subdivided. Besides, the parietes of the absorbents are thin-
nest in their passage through the glands, for, these may be ruptured by
the weight of a column of mercury which the vessels themselves are
able to support. And the action of these vessels, naturally weaker in
that situation, is still farther diminished, by the close cellular adhesion
which unites together the vessels whose union forms the glandular bo-
dies.

It was necessary that the course of the lymph should be slackened in
its passage through the glands, in order that it might undergo all the
changes which those organs are to produce upon it. Although we do
not know precisely what those changes are, their object appears to con-
sist in a more perfect union and combination of its elements, and in be-
stowing on it a certain degree of animalization, as is seen, by the greater
tendency to coagulation of the fluid taken from the vasa efferentia. Ano-
ther object of the passage of the lymph through the glands, appears to
be to deprive it of its heterogeneous particles, or at least to alter their
nature, so that they may not become injurious, when they get into the
mass of the fluids. The yellow colour of the glands through which the
absorbents of the liver pass, the dark colour of the bronchial glands, the
red colour of the mesenteric glands, in animals which have been fed on
madder or beet root, the whiteness of the same glands, while the chyle
is passing through them, are circumstances which show, that the glands
separate, or tend to separate, the colouring matter of the lymph, and that
if they do not effectually prevent its transmission into the blood, it is be-
cause certain colours, as indigo and madder, have too much tenacity,
•while other substances, as the bile, do not pass through a sufficient num-
ber of glands, to lose their colour entirely. The blood-vessels, which
are very numerous in the tissue of the conglobate glands, pour into the
lymphatics a serous fluid, which dilutes the lymph, increases its quan-
tity, and at the same time animalizes it. The number of the lymphatic
glands is very great; many are so small as to escape the eye, but become
enlarged and visible, in certain cases of disease. I have daily opportu-
nities of observing in scrophulous patients, swollen glands, in situations
in which anatomists have not pointed out any. The absorbent glands
are, at no time, so large nor numerous as in infancy. They very frequently
disappear in old people, and it is difficult to say, whether they have been
totally destroyed, or whether they are merely exceedingly reduced in
bulk.

* In some cases, the activity of the absorbents appears increased, in a singular de-
gree. Tims, jaundice has been known to be the immediate consequence of a wound of
the liver; and on other occasions, a metastasis of humours has taken place, with the
utmost rapidity. I suspect, that, in such cases, the substance that has been absorbed,
circulates by means of the anastomoses, and pervades the lymphatics with which the
whole body is covered, but without passing through the glands^ which would slacken
its course, and, to a certain degree, alter its nature — Author's Note.

XL VI. The frequent congestions of the conglobate glands, depend on
the stagnation of the lymphatic fluid in their substance, and on the com-
parative weakness of the sides of the vessels in these parts. The influ-
ence of debilitating causes on the lymphatic system, acts most powerfully
on the glands, which are the weakest part of that system. In such cases,
the vessels which enter into the composition of the glands, act feebly, or
cease to act altogether; the fluids, of which there is a continual acces-
sion, accumulate; the most liquid part alone penetrates through the
glandular organ, the grosser particles remain, the humour thickens, har-
dens, and forms congestions of various kinds. If there is a tendency to
cancer, such tumours, at first indolent, become painful, the more inspis-
sated matter being, in a manner, out of the influence of the vital power,
since its vessels are in a state of complete atony, undergoes a sort of pu-
trid fermentation, the consequence of which is a destruction and erosion
of the cellular tissue, attended by inflammation of the skin and neigh-
bouring parts. The tumour becomes, an abcess, and discharges matter
rendered liquid by the process of fermentation, and so acrid and irrita-
ting, that it extends the affection towards all the parts with which it
comes in contact.

The notions entertained hitherto on cancer, are, at once, deficient in
precision and accuracy: and it is to their fallacy, that we are to attribute
the number of contradictory opinions on the subject of its proper treat-
ment. Too precise a distinction cannot be laid down betw.een the can-
cerous or phagedenic ulcer; whose seat is always in the skin, or in the
mucous membranes (which being mere prolongation of the skin, retain
much of its structure,) and those cancers which affect the other parts of
the animal economy, especially the lymphatic glands, the testicles, and
the breasts. In the cancerous ulcers, peculiarly frequent in the face, the
lips, the tongue, in the inner coat of the stomach, of the rectum, and of
the uterus, the parts, affected with inflammation of a malignant kind, are
destroyed, without any means of checking the progress of that destruc-
tive action, the cause of action is easily conceived, while in true cancer,
the glandular tumefaction always precedes the cancerous diathesis.
As long as the affection consists merely in the obstruction of the vessels,
by indurated lymph, the tumour is indolent, and is yet only a schirrus ;
but soon all trace of organization is lost in the tumefied part, the rup-
tured vessels are lost in the mass of different substances; the process of
fermentation which takes place, converts every part into a greyish pulpy
substance, in which the most expert eye can discover no organization,
and no distinction of parts. Whenever this cancerous destruction of
parts occurs, whether the whole organ is affected, or whether the disease
extends only to a few points, extirpation is the only remedy to be em-
ployed; it is absolutely necessary, that a surgical operation should rid
the constitution of a part in which organization and life no longer exist.

The lymphatic glands which swell in the vicinity of cancerous tumours,
have already received, by means of the absorbents, the destructive germ,
and must be removed, with the rest of the diseased part, that the opera-
tion may be attended with the greater prospect of success. It is very
true, that open cancers of the breast may, for a long time, discharge
putrid matter, without inducing a cancerous affection of the glands of
the axilla. But may not the discharge, in this case, act on the principle
of revulsion; and besides, what shall we oppose to experience, which
shows that these glands, if not removed along with the cancerous breast,

136

soon become affected with cancer. If the nature of the work did Hot
circumscribe me, within certain limits, I should point out several other
particulars relative to the history of cancer, and among other cases, in
my own practice, I should relate that of a woman, in whom I removed a
cancerous tumour situated on the left side of the chest: this case is re-
markable from the number of operations which her disease required, and
for which M. Pelletan removed, six years ago, the left breast, and, three
years ago, a gland under the axilla of the same side.

The difference in the termination of glandular swellings and those
arising from cancer scrophula, or syphilis, makes it probable, that there
exist ferments, or specific poisons, which dispute the accumulated mat-
ter to undergo peculiar changes.

The venereal virus, absorbed by the lymphatics of the organs of gene-
ration, remains, for some time, in the glands of the groin, before it ex-
tends beyond, as is proved by the cure of the venereal disease, by extir-
pating the diseased glands. In short, the impediment which the lymph
meets with, in passing through the glands, shows why these parts are so
frequently the seat of critical abcesses, by which we judge of the nature
of several fevers of a malignant kind. In the plague of eastern countries,
the virus that attends this dreadful malady, is disseminated throughout
the body, collects in the glands, is transmitted through them with diffi-
culty, brings on an irritation and gangrenous inflammation, terminating
in pestilential buboes.

XLVII. The thoracic duct may be considered as the centre in which
the whole lymphatic system terminates; it arises at the upper part of
the abdomen, from the union of the chylous vessels with the lymphatics
coming from the inferior extremities. At the part where all these vessels
meet, there is a dilatation, a sort of ampullula, called lumbar cistern, re-
ceptaculum chyli, or of Pecquet, which, in truth, is not always found, and
the size of which is very variable. The thoracic duct enters the chest
through the opening in the diaphragm which transmits the aorta; it then
ascends along the spine, on the right side of the aorta, within the poste-
rior mediastinum. At the upper part of the chest, opposite to the seventh
cervical vertebra, it inclines from the right to the left side, passes behind
the oesophagus and the trachea, and o,:>ens into the subclavian vein of the
left side, at the back part of the insertion of the internal jugular into that
vein. While the thoracic duct is ascending along the spine, it receives
the lymphatics of the parietes of the chest; those of the lungs enter it as
it passes behind the root of these organs. In its course from the right
towards the left side, it receives the absorbents of the right upper ex-
tremity, and those of the right side of the head and neck. Lastly, it
unites with those vessels which are coming from the left side of the head
and neck, as well as from the left upper extremity, just before opening
into the subclavian vein. The thoracic duct sometimes has its insertion
in the jugular vein of the same side, and not unfrequently the lymphatics
of the right side of the chest, neck, and head, and of the right upper ex-
tremity, unite to form a second duct, which opens separately into the
right subclavian vein.* Whatever be the vein into which the duct opens,

* In some rare cases, lymphatic vessels, in other parts of the body, are seen to open
into neighbouring veins. This enables one to account for the presence of the chyle
which is said to have been found in the meseraic veins, into which it had been poured
by some lacteal. Mascagni was aware of this anatomical fact. The lymphatic system

w

ks structure is the same as that of the lymphatics, and its inner part is
furnished with valvular folds. Its increase of size is not progressive, as
it approaches towards its termination; on the contrary, there are. seen,
here and there, dilatations of diffeient sizes, separated by proportionate
contractions. Sometimes, it divides into several vessels which ioosculate
and form lymphatic plexuses. The opening at which the thoracic duct
enters the subclavian vein, is furnished with a valve, better calculated to
prevent the flow of blood into the lymphatic system, than to moderate the
too rapid flow of the lymph into the torrent of circulation. Compres-
sion of the thoracic duct, in aneurism of the heart and aorta, gives rise to
several kinds of dropsy, a disease always depending on the loss of equi-
librium, between the processes of inhalation and exhalation, either from
increased action of the exhalants, or from the absorbents refusing to take
up the lymph, in consequence of obstruction in the glands, or 01 com-
pression of the duct.

XL VIII. The nature of the lymph is far from being as well under-
stood, as that of the vessels along which it circulates. Haller considers
it as very analogous to the serum of the blood, and says, that this sub-
stance, to which he frequently gives the name of lymph, is like the fluid
contained in the absorbents, slightly viscous and saltish; that heat, alco-
hol, and the acids coagulate it; in short, that it possesses all the qualities
of the albuminous fluids. The serum of the blood exhaled, throughout
the extent of the internal surfaces, and even, within the substance of our
organs, by the capillary arteries, is absorbed by the lymphatics, and is
one of the principal sources of the lymph, which resembles it much. It
may be conceived, however, that the nature of the lymph must be much
more compound than that of the serum of the blood, since the lymphatic
which absorb, almost indiscriminately, every kind of substance, take up
what comes off from our organs, and the recrementitious parts of our
fluids; and these are sometimes recognizable in the absorbents, when
marked by striking qualities, as fat by its not mixing with aqueous fluids,
and bile by its deep yellow colour.

The chyle, which is necessarily affected by the various kinds of food
which we use, has different appearances in the same persons, varying
according to the quality of the different substances on which we feed ;
indigo gives it a blue colour; it is reddened by madder and beet root,
and is changed to 'green, by the colouring matter of several vegetables,
Sec. In a great number of experiments performed on living animals, it
has always appeared to me, such at it is described by authors, white,
with a slight viscidity, and very like milk, containing a very small quan-
tity of flour. It is easy to collect a certain quantity of chyle, by tying the
thoracic duct of a large dog, of a sheep, or even of a horse, as was done
several times at the veterinary school at Alfort. This fluid, when ex-
posed to the air, on cooling, separates into two parts; the one, forming
a kind of gelatinous coagulum, very thin and not unlike the buffy coat of
inflammatory blood; the other, in greater quantity and liquid, rising
above the coagulum, on its being detached from the sides of the cup to
which it adheres. The coagulated mass is semi-transparent, of a light

is, however, the most subject to deviations of any in the animal economy. — Author's
Note.

The fact referred in the above note also explains the appearance of certain sub-
stances in the blood, after the thoracic duct has been tied. — Godman.

S

138

pink colour, does not resemble the curd of milk, so that all that has been
said by a few modern physiologists, the exact resemblance which they
have pretended to discover between milk and chyle, is totally void of
foundation.

The lymph, which constantly unites with the chyle, before the latter
enters the san'guiferous system, on being received into a vessel by Mas-
cagni, coagulated in the space of seven- or ten minutes, turned sour, and
soon separated into two parts, the one more abundant, serous, in the
midst of which there floated a fibrous coagulum, which by contracting,
formed into a small cake on the surface of the fluid. Hence he concludes,
contrary to the opinion of Hew son, that lymph consists, for the greatest
part, of serum, and that fibrine constitutes its last part.

XLIX. The practice of surgery in a great hospital, has afforded me
frequent opportunities of examining the lymph which is discharged, in
abundance, from ulcerated scrophulous tumours in the groin, in the ax-
illa, and in various other parts of the body. I have always met with a
liquid nearly transparent, slightly saline, coagulable by heat, alcohol, and
the acids. Small fibrous floculi form, even on the surface of the cloths
which are wetted with it, and show the existence of two parts, the one a
gelatino-albuminous fluid holding in solution several salts; the other, in
smaller quantity, is a fibrous substance which concretes spontaneously.
The lymph, in man and the warm-blooded animals, appears to me, in
every respect similar to the fluid which is contained in the vessels of
white-blooded animals.*

* The subject of absorption has of late excited a very lively interest, and lias been
elucidated considerably by the experiments of Tiedemann and Gmelin, in Germany,
Magendie and Flandrin, in France, and Lawrance and Coates, in Philadelphia.

The conclusions drawn from the experiments of Tiedemann and Gmelin are, that the
alimentary matters, the smelling, saline, colouring, and metallic substances taken into
the stomach and intestinal canal, after being mixed with several fluids, separated from
the mass of the blood to promote assimilation ; such as the saliva, the gastric juice, and
the bile, may pass into the mass of the blood by several channels : 1st. Through the ab-
sorbents and the thoracic duct. 2d. Through absorbents which are united with veins
in the mesenteric glands. 3d. Through the roots of the venaportje. Those substances
which are conveyed into the sanguiferous system, through the thoracic duct, as chyle,
are mixed, in their pussage through the mesenteric glands and the thoracic duct, with
a reddish coagulating fluid, secreted from the arterial blood in these glands, and in the
spleen, which brings the chyle to resemble blood. The substances, however, which
are carried to the vena portze, are assimilated to the mass of the blood, by being mixed
with venous blood, and by the change which they suffer in consequence of the secre-
tion of the bile. See Phil. Med. Jour. vol. iii. p. 149.

The experiments instituted by the Philadelphia Academy of Medicine, and performed
by Drs. Lawrance and Coates, led to the following conclusions, which being drawn
after the repetition of those by Magendie, render it unnecessary to make a particular
reference to those of that gentleman. The American experimenters think that they
have established the following conclusions : 1st. That colouring matters are not ab-
sorbed by the lacteals in the living body. 2d. That camphor is absorbed with much
irregularity, and in too small quantity to afford proof of the route of absorption. 3d.
That assafoetida is permeating. 4th. That prussiate of potass enters by the lacteals and
ductus thoracicus. 5th. That mix vomica and prussic acid destroy life by their opera-
tions on the nerves, and probably in no other way. 6th. That the assertion of Magen-
die, that ink will infiltrate in the living body, is incorrect. 7th. That the odour of
camphor, assafoetida, and mint, infiltrate through the intestines. 8th. That the chemi-
cal and odoriferous substances just enumerated, are transmitted into the system with
much more delay and difficulty from the stomach than from the intestinal tube, and
wjth still less from the serous cavity of the abdomen. See Phil. Med. Jour. vol. iii.
p. 273.

139

CHAPTER III.

OF THE CIRCULATION.

L. THE term circulation is applied to that motion by which the blood,
setting out from the heart, is incessantly carried to all parts of the body
by means of the arteries, and returns by the veins, to the centre whence
it began its circuit.

The uses of this circulatory motion, are to expose the blood, changed
by mixing with the lymph and the chyle, to the air in the lungs (respira-
tion^) to convey it to several viscera, in which it passes through different
steps of purification (secretions /) and to send it into the organs whose
growth is to be promoted, or whose losses are to be repaired, by the nu-
tritive and acimalized part of the blood brought into a state of perfection
by these successive processes (nutrition.']

The circulatory organs are less useful in elaborating, than in convey-
ing the fluids. To form a just conception of their uses, one may com-
pare them to those workmen in a large manufactory in which various
kinds of goods are made, who are employed in carrying the materials
to those who are to work them; and as among the latter, some finish the
work, while others prepare the materials, so the lungs to the secretory
glands are continually occupied in separating from the blood whatever is
too heterogeneous to our nature to become assimilated to our organs, or
to afford them nourishment.

To understand, thoroughly, the mechanism of this function, it is neces-
sary to study separately the action of the heart, that of the arteries which
arise from it, and, lastly, that of the veins which enter it. The union of
these three classes of organs, forms the circle of the circulation.

LI. Of the action cf the heart. In man, and in all warm-blooded ani-
mals, the heart is a hollow muscle, the inner part of which is divided into
four large cavities which communicate with one another ; from these,
vessels arise which convey the blood to all parts of the body, and the ves-
sels which bring it back from all those parts, likewise terminate in these
cavities.

The heart is placed in the chest, between the lungs, above the dia-
phragm, whose motions it follows; it is surrounded by the pericardium,
a dense and fibrous membrane admitting of very slight extension, closely
united to the substance of the diaphragm, covering the heart and great
vessels, without containing them in its cavity, furnishing an external co-
vering to the heart, and bedewing its surface with a serous fluid, which
never accumulating, except in disease, facilitates its motion, and prevents

An admirable series of experiments were subsequently performed by Dr. J. O'B.
Lawrance, and Dr. B. II. Coates, in which they very clearly establish, that articles
taken into the stomach may escape by three outlets for absorption. By the vena portae,
the cesophageal veins, and the thoracic duct ; and if all these be closed, the absorbed
matter no longer finds its way into the circulation or urine. See Phil. Med. Jour. vol.
v. p. 327 — Godman.

See APPENDIX, Note Q.

140

its adhering to the neighbouring parts. The principal use of the peri'
cardium, is to fix the heart in its place, to prevents its being displaced
into other parts of the chest, which could not happen, without occasion-
ing a fatal disorder in the circulation. If, after having laid open the
chest of a living animal, by raising the sternum, an incision is made into
the pericardium, the heart protrudes through the opening, and moves to
the right and left by bending itself on the origin of the large vessels ; the
course of the blood is then intercepted, and the animal threatened with
immediate suffocation.

In man, the heart is placed nearly towards the union of the upper
third of the body, with the lower two-thirds; it is, therefore, nearer to
the upper parts; it holds them under a more immediate controul, and as
that organ keeps up the action of all the rest, by the blood which it sends
into them, the parts above the diaphragm have much more vitality than
the parts beneath. The skin of the upper part of the body, and espe-
cially of the face, has more colour, and is warmer than that of the lower
parts; the phenomena of diseases come on more rapidly in the upper
parts; they are, however, less liable to put on a chronic character.

The bulk of the heart, compared to that of other parts, is larger in the
foetus, than in the child that has breathed; in short men, than in those of
high stature. The heart is likewise larger, the stronger, and more pow-
erful in courageous animals than in weak and timid creatures.

This is the first instance of a moral quality depending on a physical
disposition of parts ; it is one of the most striking proofs of the influence
of the moral character of man on his physical nature. Courage arises
out of the consciousness of strength, and the latter is in proportion to
the activity with which the heart propels the blood towards all the or-
gans. The inward sensation occasioned by the afflux of the blood, is the
more lively, and the better felt, when the heart is powerful. It is on that
account that some passions, for example, anger, by increasing the ac-
tion of the heart, increase a hundred fold both the strength and courage,
while fear produces an opposite effect. Every being that is feeble, is
timorous, shuns danger, because an inward feeling warns him, that he
does not possess sufficient strength to resist it. It may perhaps be ob-
jected, that some animals, as the turkey cock and the ostrich, possess
less courage than the least bird of prey, that the ox has less than the lion
and other carnivorous animals. What has been said does not apply to
the absolute, but to the relative size of the heart. Now, though the heart
of a hawk be absolutely smaller than that of a turkey cock, it is neverthe-
less larger, in proportion to the other parts of the animal. Besides, the
bird of prey, like the other carnivorous animals, in part owes his courage
to the strength of his weapons of offence.

Another objection, more specious, but not better founded, is drawn
from the courage manifested, on certain occasions, by the most timid
animals, for example, by the hen in protecting her young ; from the
courage with which other animals pressed by hunger or lust, surmount
all obstacles, but particularly from the heroic valour of men of the most
feeble bodies. All these facts, however, are only proofs of the influence
of the mind on the body. In civilized man, the prejudices of honour, in-
terested considerations, and a thousand other circumstances, degrade
the natural inclinations of man, so as to make a coward of one whose
strength is such as would induce him to brave all kinds of dangers, while
on the other hand, men whose organization should render them most

141

timid, arc inspired to perform the most daring actions. But all these
passions, all these moral affections, operate only by increasing the action
of the heart, by increasing the frequency and the force of its pulsations,
so that it excites the brain or the muscular system, by a more abundant
supply of blood.

The heart is not quite ovoid in man as it is in several animals, nor is it
parallel to the vertebral column, but it lies obliquely, and is flattened to-
wards the side next the diaphragm on which it rests.

Of the four cavities which form the heart, two are, in a measure, ac-
cessary, viz. the auricles; they are small musculo-membranous bags op-
posed to each other, receiving the blood of all the veins, and pouring that
fluid into the ventricles at the base of which the auricles are, as it were,
applied. The ventricles arc two muscular bags separated by a partition
of the same nature, and belonging equally to both ; they form the greatest
part of the heart, and give origin to the arteries.

The auricle and ventricle on the right side, are larger than those on
the left. But that difference of size depends as much on the manner in
which the blood circulates, at the approach of death, as on the original
conformation of the lungs. On the point of death, the lungs expand with
difficulty, and the blood sent into them, by the contractions of the right
ventricle, being no longer able to circulate through them, collects in that
cavity, flows back into the right auricle, in which the veins continue to
deposit blood, stretches their parietes, and increases considerably the di-
mensions of those cavities. The capacity of the right cavities is, how-
ever, originally greater than that of the left, and is proportioned to that
of the venous system which opens into it. The right cavities of the
heart, which might be called its venous cavities, have likewise thinner
parietes than the left or arterial, and, in this respect, the same difference
is observed, as in the parietes of the arteries and veins. The right ven-
tricle having to send the blood destined to the lungs, to a very short dis-
tance, and through a tissue easily penetrated, requires but a moderate im-
pelling force.

As, will be shown, in speaking of respiration, a function of which the
physiological history is not easily separated from that of the circulation,
the heart may further be considered as formed of two parts in contact,
the one right or venous, the. other left or arterial. Notwithstanding the
juxta position of these two parts of the same organ, they are perfectly
distinct,^ and the blood in each cavity is very different from that in the
other. The blood, in the adult, can never pass immediately from the
one to the other; the right side of the heart receives the blood of the
•whole body, and transmits it to the lungs; the left side of the heart re-
ceives the blood of the lungs, and distributes it over the whole body, so
that, in a physiological point of view, the lungs form a part of the circle
of the circulation, and serve as an indispensable medium between the
two divisions of the heart, and as will be seen hereafter, their part of the
circle is, by no means, the least important.

If there existed, between the ventricles, a direct communication, the
venous blood would mix with the arterial, and the union of these two
fluids would mutually impair the qualities of each. Recent observations
have furnished an opportunity of judging of the effects of such a commu-
nication between the ventricles, which had been imagined by the ancients,
but of which no case had yet been met with. A man, forty-one years of
age, came to the Hopital de la Charite, to undergo the operation of litho-

142

tomy. He was remarkable for the lividity of his complexion, the turges-
cence of the vessels of the conjunctiva, and the thickness of his lips,
which like the rest of his face, were of a dark colour, his respiration
was laborious, his pulse irregular, he could not utter two words in suc-
cession without taking breath ; was obliged to sleep in a sitting posture,
and was particularly remarkable for his indolence. This indolence, join-
ed to great simplicity of nature, was such, that he had never been able to
maintain himself without the assistance of his wife. A very small quan-
tity of blood was taken from his arm, in consequence of which his pains
were diminished, but his difficulty of breathing increased, was followed
by syncope, and he died from suffocation. On opening his body, his heart
was found filled with blood, and especially the right auricle, which was
considerably distended ; the pulmonary artery was aneurismal, and uni-
formly distended from the right ventricle, to its division ; none of its
coats had yet given way. The two ventricles of the heart were of nearly
the same capacity, and the relative thickness of their parietes did not
vary so much as in health. The partition between them, contained an
opening of communication of an oblong shape, about half an inch in ex-
tent, and directed obliquely from below upwards, from before backward,
and from left to right, so that, not only the direction of the opening, but
likewise a kind of valve formed in the right ventricle, by a fleshy column,
so placed as to prevent the return of the blood into the left ventricle :
clearly showed, that the blood flowed from the left into the right ventri-
cle, and thence into the pulmonary artery. Theductus arteriosus,an inch
in length, and large enough to admit a goose quill, allowed, as in the foe-
tus, a free passage to the blood, from the pulmonary artery into the aorta.
The foramen ovale was closed.

This singular conformation explains, in the most satisfactory manner,
the phenomena observed during the life of the patient, and the organic
affection of the pulmonary artery. There was necessarily, in this vessel,
a mixture of venous and arterial blood, and this blood was sent into it, in
part by the action of the left ventricle, with an increased impetus, which
accounts for the aneurism. The blood which reached the lungs was al-
ready vivified, and required less action from that organ, to complete its
oxyd'ation; on the other hand, the right auricle emptied itself, with dif-
ficulty, into the right ventricle, in part filled with the blood which the
left ventricle sent into it with greater force: hence the extreme difficulty
in the venous circulation, the lividity of the complexion, the colour and
the puffiness of the face, the habitual and general torpor. This state of
langour and inactivity might, likewise, depend on the flow of the venous
blood into the aorta, along the ductus arteriosus. It is worthy of obser-
vation, however, that this impure blood was not transmitted to the brain,
whose vital excitement it would not have been able to maintain.
lower extremities bore no proportion to the upper, and this inequality
analogous to what is observed in the foetus, depended on a similar cause.
This morbid preparation was deposited by M. Deschamps, in the museum
of the Ecole de Medicine of Paris, and was, by their desire, modelled in
wax. M. Beauchene, junior, presented the same museum with a similar
preparation, which he procured from a subject in the dissecting room.

Several anatomists have paid attention to the structure of the heart;
much has been said on the subject of the peculiar arrangement of the
muscular fibres which form its 'parietes, yet, the only result that can be
obtained from all these researches is, that it is absolutely impossible to

143

unravel the intricacy of these fibres*. Fibres of the ordinary structure,'
and crossing each other, in various directions, form the two auricles;
other and more numerous fibres form the parietesof the ventricles, reach
from the apex to the base, extend into the septum which divides them,

* On this point the author is by no means correct. The structure of the heart may
be demonstrated with tolerable accuracy. The latest and best description of it has been
furnished by J. F. VAUSS, teacher of anatomy in the University of Liege.

As an accurate view of the distribution of its fibres is requisite to enable us to know
the nature of the actions of this viscus, the following account by this anatomist is here
introduced : —

" The heart is a conical hollow muscle, covered by the serous membrane, the peri-
cardium— lined by a membrane, which is of a different, nature in each ventricle, and
composed of three layers of muscular fibres : the superficial one common to both ven-
tricles—the middle one at least four times as large as the preceding, and like it, com-
mon to the two great cavities of the heart — and the lower one, divided into two parts,
the right and the left, each belonging to the corresponding ventricle ; both of them
forming the septum by their junction, and giving birth to the column® carneae.

" The other layer is very fine ; its bundles of fibres which become more oblique as
they get lower, are directed, the anterior ones from the right to the left, and the pos-
terior ones from left to right, from the base to the apex of the heart, where they are
confounded with the fibres of the middle layer.

" The fibres of the middle layer are much more numerous, and follow the same di-
rection ; only they are more oblique, and are not all of them earned to the apex of the
heart. The inferior fibres only reach the apex, and are there confounded with the fibres
of the outer layers. Whilst the others, according as they become more superficial,
reach the posterior farrow, where the layer untwists itself, to form the two unequal
portions which compose the lower layer of each ventricle.

" The lower layer of the right ventricle, which is much thinner than that of the left,
separates itself from the latter on a level with the posterior furrow, and is earned back-
wards, on the outside, before, and then within the ventricle which it immediately en-
velopes. All its bundles bencl from below upwards, and, crossing the direction of those
of the middle layer, are fixed, the upper ones, which are almost transverse, to the cir-
cumference of the auriculo-ventricular opening, and to the anterior part of the mouth
of the pulmonory artery— the others, which are longer and more oblique, and which
form the right side of the septum, successively to the part of that orifice which is be-
tween the two ventricles, and to its posterior part.

" The lower layer of the left ventricle, which is much thicker than that of the right,
arises like it from the middle laver, on a level with the posterior furrow. Its bundles
r^n from behind to before, between the two cavities, thus forming- the left side of the
septum, reach the anterior furrow, then, running from right to left, and from below up-
wards, they surround the ventricles ; and, crossing the line of the bundles of the middle
layer, are fixed successively, one by the side of the other, to the origin of the aorta, and
to the opening of communication between the ventricle and auricle, all the way to the
upper extremity of the posterior furrow.

«* The lowest bundles on each side alone follow a different direction. These bundles
after separating from the others, approach the centre of the corresponding ventricle,
and form the columnx carneae of the heart.

" Thus all the fibres of the superficial layer take the form of a lengthened spiral,
which takes a direction from the base towards the apex of the heart, where the fibres
are confounded with those of the middle layer, after having made a turn or a turn and
a half. Those of the middle layer have the same form, the same general direction, and
the same origin ; but they are more oblique, and are so arranged, that one part only
of them reach the apex of the heart, whilst the greater part terminate at its posterior
furrow. Those of the last layer of each ventricle have still a spiral form, but the screw
takes the inverse direction, for the fibres stretch from the posterior furrow to the base
of the heart; and they do not reach that part until they have surrounded the corres-
ponding ventricle from right to left, crdfesing the line of the fibres of the two other lay-
ers. The septum is formed by the junction of the two lower layers with the addition
of a few bundles, which run from the apex of the heart, and appertain to the middle
and superficial layers, which are mixed together at that part.

" The structure of the auricles is less regular. In general, the fleshy fibres pass from

144

pass from the one to the other, arid are lost into each other, in several
points. They are exceedingly red, short, close, and united by a cellular
tissue, in \vhich fat scarcely ever accumulates.

These fibres forcibly pressed against each other, form a tissue similar
to the fleshy part of the tongue, endowed with but little sensibility, but
contractile in the highest degree. Vessels and nerves, in considerable
number, if compared to the bulk of the heart, pervade this muscular tissue,
whose contraction, whatever in other respects may be the direction of its
fibres, tends to draw towards the centre of the cavities, every point of
their parietes. Lastly, a very fine membrane lipes the inner part of these
cavities, facilitates the flow of blood, and prevents the infiltration of that
fluid.

LII. If we suppose, for a moment, that all the cavities of the heart are
perfectly emptied of blood, and that they fill in succession, the following
may be considered as the mechanism of the circulation through the heart.
The blood brought back from every part of the body, and deposited into
the right auricle, by the two vense cavse, and by the coronary vein, sepa-
rates its parietes and dilates it, in every direction. The irritation attend-
ing the presence of the blood, stimulates the auricle to contraction; this
fluid, which is incompressible, flows back, in part, into the veins, but it
chiefly passes into the pulmonary ventricle, through a large aperture, by
means of which it communicates with the right auricle. The auricle,
after freeing itself of the blood with which it is filled, relaxes and again
dilates by the accession of a new supply of this fluid, continually brought
by the veins which open into it.

However the right ventricle, filled with the blood which it has received
from the auricle, contracts in its turn on the fluid whose presence excites
its parietes, and tends, in part, to return it into the right auricle, and to
send it along the pulmonary artery. Regurgitation from the ventricle into
the auricle, is prevented by the tricuspid valve, a membranous ring sur-
rounding the edge of the opening of communication, and the free edge of
which is divided into three divisions, to which are attached small tendons
terminating into the columnae carnae of the heart. Three valves laid
against the parietes of the ventricle, the instant the blood passes in to its ca-
vity, recede from them when it contracts, and rise towards the auricula^
opening. They cannot be forced into the auricle, as their free and loose edge
is kept in its situation by the columnae carnse, which are like so many little
muscles whose tendons inserted into loose edges of the valves, bind them
down when the stream of blood tends to form those membranous folds
towards the auricles. The three divisions, however, of the tricuspid
valve, by rising towards the auricular aperture, return into the auricle,
all the blood contained in the inverted cone which they form, immediately
before rising. Besides, these three portions of the tricuspid valve do not
close completely the aperture, around which they are placed, they are
perforated by a number of small holes: a part of the blood, therefore, re-
turns into the auricle, but the greatest portion is sent into the pulmonary
artery. The action of this vessel begins, when the parietes of the ventri-

the circumference of the mouths of the veins, aftd from the auricolo-ventricular open-
ing, to be distributed over the parietes, and especially on the septum ; where, in the
situation of the fossa ovalis, they form two crescents, the concave parts of which are
opposed to each other." — Copland.
For remarks on the functions of the heart, see APPENDIX, Note R.

145

cal

are in a state of relaxation, and the blood would be forced back into
the ventricle, if the sigmoid valves, by rising suddenly, did not prevent
it. Supported on a kind of floor formed by three valves, which lie across
the calibre of the vessel, the blood pervades the tissue of the lungs, and
flows along the divisions of the pulmonary vessels; from the arteries it
passes into the veins, and these, four in number, convey it into the left
auricle. This auricle, stimulated by the presence of the blood, contracts
in the same manner as the right, part of the blood flows back into the
lungs, but the greatest part enters the last ventricle, which sends it along
the aorta, to every part of the body, whence it returns to the heart by the
veins. The return of the blood into the left auricle, is prevented by the
mitral valve which is similar to the t-ricuspid, except that its loose edge is
divided only into two divisions. As soon as the blood has reached the
aorta, this vessel contracts, its sigmoid valves fall, and the blood is sent
to every part of the body which isv supplied by some of the innumerable
branches of that great artery.

In a natural state, the circulation is not carried on as has been just
stated; and, we have supposed this successive action of the four cavities
of the heart, only to render more intelligibler'the mechanism of the circu-
lation in that organ. If we Jay bare the heart in a living animal, we ob-
serve, that the two auricles contract at the same time, that the contrac-
tion of the ventricle is likewise simultaneous, so that while the auricles
are contracting, to expel the blood which fills them, the ventricles are
dilating to receive it. This successive contraction of the auricles and
ventricles is readily explained, by the alternate application of the stimu-
lus which determines the action of these cavities. The blood which the
veins bring into the auricles, does not excite their contraction, till a suf-
ficient quantity has been collected. While this accumulation is taking
place, they yield, and the resistence which is felt on touching them, dur-
ing their diastole, depends, almost entirely, on the presence of the blood
which separates and supports their parietes. The same applies to the
ventricles; they cannot contract, until a sufficient quantity of blood is
collected within them; that there remains some blood in these cavities,
(for they are never completely emptied,) is no objection to the theory;
since this small quantity is not sufficient to bring on contraction of the
heart, and is not worth taking into account.

If I am asked, why the four cavities of the heart do not all contract at
once, I answer, that it is easier to assign the final than the proximate
cause. If the contraction of these cavities had been simultaneous, in-
stead of being successive, it is evident that the. auricles could not have
emptied themselves into the ventricles. The alternate action is more-
over absolutely necessary, as the heart, as well as the other organs,
is unable to keep up a perpetual action; the principle of its motion,
which is soon exhausted, being incapable of restoring itself, except dur-
ing rest. But, as was observed at the beginning of this work, in speak-
ing of the vital power and functions, the alternations of action and repose
in organs which, like the heart, perform functions essential to life, must
be extremely short in their duration, and at very close intervals.

The cavities of the heart, however, are not entirely passive during
dilatation, and the action of that organ does not wholly depend on the
excitement of the blood on its parietes, since the heart after it has been
torn from the body of a living animal, palpitates, its cavities contract
and dilate, though quite emptied of blood, and appear agitated by alter-

146

nate motions, which become fainter as the part gets cold. If you attempt
to check the diastole of the heart, the organ resists the hand which com-
presses it, and its cavities appear endowed with a power which Galen
termed pulsive; in virtue of which they dilate to receive the blood, and
not because they receive it. In that respect, the heart differs essentially
from the arteries, whose dilatation is occasioned by the presence of the
blood, whatever some physiologists may have said to the contrary. I
have repeated, but unsuccessfully, the famous experiment by which it is
attempted to be proved, that these vessels have the power of moving in-
dependently of the presence of the blood. An artery tied ar.d emptied
of blood, contracts between the two ligatures, and is no longer seen to
move in alternate contractions.

LIII. The heart manifestly shortens itself, and the base approaches
towards the apex, during the systole or contraction of the ventricles. If
it became elongated, as some anatomists have thought, the tricuspid and
miral valves would ie incapable of fulfilling the functions to which they
are destined, since the columnae earner, whose tendons are inserted in
the edges of these valves, would keep them applied to the parietes of the
ventricles. The pulsations which are felt, in the interval between the
cartilages of the fifth and sixth true ribs, are occasioned by the apex of
the heart which strikes against the parietes of the chest. In the expla-
nation of this phenomenon, it is not necessary to admit the elongation of
the heart during its systole; it is sufficient to consider, that the base of
the heart, in which the auricles are situated, rests against the vertebral
column; that these two cavities, by dilating at the same time, and by their
inability to move the vertebrae, before which they are situated, displace
the heart, and thrust it downwards and forwards. This motion depends,
likewise, on the effort which the blood sent into the aorta makes, to
bring to a straight line, the curvature of that artery, which re-acts and
carries downwards and forwards the whole mass of the heart, as it were,
suspended to it.

The quantity of blood which each contraction of the ventricles sends
into the aorta and pulmonary artery, most probably, does not exceed two
ounces in each of these vessels. The force with which the heart acts on
the blood which it sends into them, is but imperfectly known, however
numerous the calculations by which it has been endeavoured to solve
this physiological problem. In fact, from Keil, who estimates at a few
ounces only, the force of the heart, to Borelli, who makes it amount to
one hundred and eighty thousand pounds, we have the calculation of Mi-
chelot, Jurine, Robinson, Morgan, Hales, Sauvages, Cheselden, Sec.; but
as Vicq-d'Azyr observes, not one of these calculations is without some
error, either anatomical or arithmetical: hence we may conclude with
Haller, that the force of the heart is great, but that it is, perhaps, im-
possible to estimate it with mathematical precision. If we open the
chest of a living animal, and make a puncture in his heart, and introduce
a finger into the wound, a considerable pressure is felt, during the con-
traction of the ventricles*.

* The difficulty of determining the exact degree of power exerted by the heart, is
strikingly illustrated by the total disagreement in the estimates of different writers.
Before we engage in an} calculations respecting the matter, the following data should
be clearly established.

1. The quantity of blood expelled from each ventricle at every contraction*

147

Those who admit, to its full extent, Harvey's opinion on the circula-
tion of the blood, and who think with him, that the heart is the sole agent
of the circulation, overrate the power of that organ, so as to proportion
it to the extent of the course which the blood is to take, and to the num-
ber of the obstacles which it is to meet in its way. But, as I am about
to state, the blood-vessels should not be considered as inert tubes, in
which the blood flows from the mere impulse which it has received from
the heart.

LIV. Of the action of the arteries. There is no part of the body to which
the .heart does not send blood by the arteries, for, it is impossible to
make a puncture, with the finest netdle, into any of our organs, without
wounding several of these vessels, and causing an effusion of blood. The
aortic arterial system may be compared to a tree, whose trunk, repre-
sented by the aorta, having its root in the left ventricle of the heart, ex-
tends afar its branches, and throws out, on every side, its numerous ra-
mifications. The siz3 of the arteries decreases, the farther they are from
the trunk by which they are given off. Their form, however, is not that
ot a cone, they are rather cylinders arising from one another, and de-
creasing successively in size. As the branches given off by a trunk, taken
collectively, have a greater diameter than that of the trunk itself, the ca-
pacity of the arterial system increases with the distance from the heart,
hence it follows, that as the blood is continually flowing from a straighter
to a wider channel, its course must slacken. The direction of the arte-

2. The degree of velocity with which it is expelled.

3. The amount of resistence which each ventricle lias to overcome, before it can
propel the blood into its corresponding arteries.

4. The effects of the action of" the heart on the blood.

But these are points which seem likely never to be ascertained with any sort of pre-
cision, and of course Aur computations must continue as heretofore, vague and conjec-
tural. All we know with certainty on the subject is, that the heart is a muscle of great
strength, as is evinced by the phenomena of the circulation, and further, by the fact
that, if the heart of a living animal be grasped, no effort of the hand will repress its
action.

An inquiry far more interesting here presents itself. Why, as has been frequently
asked, does not the heart become exhausted, like other muscles, by exertion ?

Three answers to this intricate question have been attempted, no one of which, how-
ever, is at all satisfactory.

1. By Willis it is maintained, that the voluntary muscles derive their nerves from the
cerebrum, while the cerebellum supplies the heart and other involuntary muscles ; and
hence he infers that the one set is thereby fitted for temporary, and the other for per-
manent, and uninterrupted action.

Admitting the statement to be anatomically correct, we do not perceive that it leads
to any such conclusion. But it is not so. There are many exceptions to this alleged dis-
tribution of the nerves.

2. By Stahl, it is imputed altogether to the intelligence of his anima medica, a guar-
dian power, that foreseeing the danger to which the system would be exposed by any
remission in the action of the heart, ordains it otherwise. This is all hypothesis, and
of the most wretched kind too ; by the adoption of which we only cut the knot that
perplexed us to untie.

3. By Haller it is accounted for on the supposition of a larger share of irritability be-
ing possessed by the heart. It is to be recollected, that he judged of the degree of
this property by the duration of the contractile power in a part, after the death of the
animal. Taking this as a just criterion, it will appear from the experiments of Fowler,
that in cold-blooded animals, at least, the voluntary museles retain their irritability longer
than the heart itself. The difference, indeed, in this respect, in any class of animals,
is so slight, that other objections aside, the hypothesis could not be entertained.—
Chapman.

148

ries is often tortuous, and it is observed, that the arteries which are sent
to hollow viscera, as the stomach, the uterus, and the bladder, or other
parts capable of contracting, of stretching, and of changing their dimen-
sions every moment, as the lips, are much the most curved, no doubt,
that they may by unfolding, give way to the extension of the tissues into
which they are distributed. Lastly, the arteries arise from one another,
and form with the trunk or branch from which they are given off, an
angle varying in size, but which is always obtuse, and more or less acute
towards the branch.

As the arteries recede from their origin, they communicate together,
and these anastomoses form arches, two branches bending towards each
other, and joining at their extremities, as we see in the vessels of the
mesentery; sometimes two parallel branches meet at an acute angle,
and unite into one trunk, thus the two vertebrals join to form the basilar
artery: some communicate by transverse branches, which pass from the
one to the other, as is seen within the skull.

In the anastomoses of the first kind, the columns of blood Sowing, in
contrary directions, along the two branches, meet at the point of union?
and mutually repel each other, their particles mingle, and lose much of
their motion in that reciprocal shock. The blood then follows a middle
direction, and enters the branches which arise from the convexity of
these anastomotic arches.

When two branches unite to produce a new artery, of a greater calibre
than each taken separately, but not so large as both together, the motion
of the blood becomes accelerated, because it passes from a more capacious
into a straighter channel, and the forces which determined its progression,
are concentrated into one. Lastly, the transverse anastomoses are well
calculated to promote the passage of the blood from the one branch into
the other, and to prevent congestion in the parts.

LV. The arteries are imbedded in a certain quantity of cellular tissue,
are almost universally accompanied by corresponding veins, by lympha-
tics and nerves, and their coats are thicker in proportion as their calibre
is smaller. The experiments of Clifton Wintringham prove, that the
parietes are stronger in the small than in the large arteries, hence it is
observed, that aneurisms are much less frequent in the former. Their
parietes have sufficient firmness not to collapse, when the tube of the ar-
tery is empty. They are formed of three coats; the external or cellular
admits of considerable extension, and appears to be formed by the con-
densation of the lamina of the cellular tissue, which surrounds the arte-
ry, and unites it to the neighbouring parts. The second coat is thicker
and firmer, of a yellow colour, and fibrous, and is by some considered as
muscular* and contractile, while other physiologists merely allow it to
possess a considerable degree of elasticity. The longitudinal fibres, ad-
mitted by some authors in the texture of this second coat cannot be dis-
tinguished, and their existence is not necessary to account for the longi-
tudinal retraction of arteries. In fact, this retraction might depend on

* If in man and the greater number of animals, the yellow fibres which form this
coat, differ greatly from muscular fibres, they in the elephant resemble that texture
very completely, as I had an opportunity of observing1, when I witnessed the dissection
of the elephant that died in the year 1802, at the Museum of Natural History. Let men
of judgment decide whether the analogy is sufficient to warrant our admitting, in the
arteries of the human body, the existence of muscular fibres.— Author's Nate.

149

elasticity, it might likewise be occasioned by the contraction of fibres
not absolutely circular nor longitudinal, but spiral and imperfectly sur-
rounding the vessel, and crossing each other in various directions. This
yellow coat, thicker in proportion in the smaller arterial twigs, than in
the larger branches, and thicker in these than in the trunks, is dry, hard,
not capable of much extension, and is ruptured by an effort to which the
external coat yields by stretching. Lastly, a third, thin, and epidermoid
coat lines the inside of these vessels, and seems less adapted to give
strength to the parietes of the arteries, than to facilitate the flow of the
blood, by presenting to it a smooth, even, and slippery surface, continu-
ally moistened by a serous exudation, from the minute arteries, or vasa
vasorum, which are distributed between these coats*.

Besides these three coats, the great arteries receive a fourth from the
membranes lining the great cavities; thus, the pericardium and the
pleura in the chest, the peritoneum in the abdomen, furnish to the dif-
ferent parts of the aorta, an adventitious coat which does not completely
surround the vessel.

Of the three coats which form the parietes of the arteries, the fibrous,
though thicker than the other two, offers, however, the least resistance.
If you take the carotid artery, which for a considerable space, does not
send off any branches, and forcibly inject into it a fluid, the internal and
middle coat will be torn, before dilatation has increased, by one-half, the
calibre of the vessel. The external coat resists the cause of rupture,
by dilating, and forms a tumour, and it is only by applying a conside-
rable force, that it can be ruptured. The experiment is attended with
the same success, if performed with air or any other gas. In aneu-
rism, the internal and fibrous coats of the arteries, but more particularly
the fibrous, are ruptured at an early stage of the disease, which at that
period increases suddenly, in a very rapid manner, and on opening the
tumour, it is observed, that the sac is entirely formed by the dilated cel-
lular coat. Take an artery of a certain calibre, for example the carotid
or humeral, apply a ligature around it, and tighten it with some degree of
force. Dissect and take out the vessel, then cut the thread, and examine
the place to which it was applied, you will observe, that the parietes of
the artery are in that part thinner, and formed merely by the cellular
coat which alone has withstood the constriction. Take hold of the two
ends of an insulated arterial tubt, and stretch it, then examine its inner
coat, and you will find it torn and cracked in several places, and the pa-
rietes of the artery evidently weakened!-

LVI. This want of extensibility in the coats of arteries, is the princi-
pal cause of aneurism ; hence the popliteal artery is so liable to that af-
fection, from its situation behind the keee, whose extension is limited,
merely by the resistance of the posterior tendons and ligaments: this ar-
tery is affected by the jar which takes place through all the soft parts,
when the leg is violently extended; and being less extensible than the
other parts, its inner coat is ruptured, or at least weakened, so as to oc-
casion an aneurism, always rapid in its progress. Of ten popliteal aneu-
risms which I have seen in different hospitals, eight were ascribed to a

* See APPENDIX, Note R, for remarks on the structure and action of the arteries.
7 For a full relation of the effects of ligatures on arteries, see « Jones on Hemorr-
hage."— Godman,

150

violent extension of the ham. In looking over the cases that have been
recorded, it will be seen, that a considerable number of aneurisms of the
aorta, have been occasioned by too forcible arid too sudden an extension of
the trunk in raising a heavy burthen.

From the dryness, the frailly of the yellow or fibrous coat of arteries,
the application of ligatures to these vessels is attended with a speedy la-
ceration of their tissue; a moderate degree of compression is sufficient
to rupture that coat, the external and internal remaining, at the same
time, uninjured, provided the constriction be not excessive. Why is the
arterial tissue, almost the only one on which ligatures require to be ap-
plied, the least fitted of all the organic tissues to bear them ? This incon-
venience attending «the ligature of arteries, led Pouteau to prefer tying
arteries so as to include the surrounding soft parts within the ligature,
though this process is, in other respects, less eligible. The objections
will be obviated, by employing flat ligatures, which, by acting on a great-
er surface of the artery, are less likely to divide the coats of the vessel,
which will become obliterated at the spot to which the ligature is applied,
the more rapidly as the patient is younger and stronger.

I once saw, in a man whose thigh was amputated, on account of caries
of the knee joint combined with a scorbutic affection, hemorrhage attend
the fall of the ligatures, which did not come away till nineteen days after
the operation; as if the fibrous coat of these arteries, partaking in the
debility of the muscular organs, had not preserved a sufficient degree of
contractile power to close the cavity of the vessel.

LVJI. The contractile power of the arteries is in their middle coat,
it is greater, as this coat is thicker in proportion to the calibre of the ar-
tery. Hence, as Hunter observes, in his work on the blood and inflam-
mation, the larger arteries are endowed with elasticity, merely, while
on the other hand, contractility is very apparent in those of a smaller ca-
libre, and is found complete in the capillary vessels * ; hence, in the trunks
near the heart, the progression of the blood is effected, chiefly by the
impulse which it receives from the heart, and as Lazarus Riviere ob-
served, the circulation of the blood in the large vessels, is more an hy-
draulic than a v tal phenomenon. The action of the main arterial trunks,
near the heart, has so little influence on the motion of the blood sent in-
to them by that organ, that the aorta is frequently ossified, without af-
fecting the circulation. The aorta is n&urally bony in the sturgeon. J.
L. Petit, in the case of a bookseller, whose leg he had taken off, found all
the arteries of a certain calibre in a state of ossification; they were indu-
rated, and of course, incapable of acting, in the slightest degree, on the
column of blood which flowed along them. All these facts seem conclu-
sive arguments in favour of those physiologists, who explain, on theprin-

* This is not altogether correct. Every portion of the arterial system is unquesti-
onably possessed of the property of contractility. In the larger vessels, muscular fibres
are even demonstrated to the eye. Besides, mere elasticity will not explain many of
the phenomena of arterial action. Contrary to the doctrine of Mr. Hunter, it was mam-
tained by Baron Haller, and indeed by almost all the coteroporary physiologists, that
contractility belongs exclusively to the large and middle sized arteries. In this, how-
ever, they were deceived.

It is now well ascertained, that muscularity increases exactly as the vessel recedes
from the heart, the capillaries having it in the greatest degree. As far as I know, this
opinion was originally taught by Cullen, and afterwards fully confirmed by the experi-
ments of Hunter. —Chapman.

151

dple of elasticity, the contraction of arteries. But however correct this
explanation may be, with regard to the vessels near the heart, it does not
apply to the capillaries; the influence of that organ does not operate on
these vessels. One may easily conceive, that the column of blood which
by the impulse it has received, in the first instance, has been sent along
the whole length of tubes whose sides are ossified, inflexible, and conse-
quently inert, on reaching the extremity of these canals, is, in a manner,
again taken up by the vital power residing in the capillary vessels, and
circulates from the influence of the action belonging to these vessels*.
Besides, elasticity, however considerable, merely restores those tissues
that have been stretched, to the condition in which they were before ex-
tension. Elasticity is a kind of re-action, proportionate or relative to the
action which precedes it. Why do arteries in the living body contract,
to such a degree, that when empty, their canal becomes obliterated,
while in the dead body, however perfect the depletion of the arterial
system may have been, the cavity of the arteries remains perfectly open.
Several physiologists, however, and those among- the most modern, con-
sider elasticity as the principal cause of the progression of the blood
along the arteriesf.

As the distance from the centre increases the circulation slackens, from
several causes, and the blood could not reach all the parts of the body, if
the arteries, whose vitality increases with their distance from the heart,
and as they become smaller, did not propel it to all the organs. The
causes which retard the circulation of the arterial blood, are, the increased
dimensions of the space in which it is contained ; — the resistance from the
curves of the vessels; — the friction which it undergoes, and which in-

* I have dissected the brain of a female, (apparently1 between fifty and sixty years
old,) in which the arteries were rigidly ossified from their great trunks, down to
branches not larger than a tine knitting1 needle. In the left thalamus opticus there was
a brownish discolouration, which seemed to m-.irk the spot where blood had been ef-
fused some time before death. — Godman.

-j- It has always been a matter of controversy among physiologists, whether the blood
is propelled by the heart only, or whether the" arteries co-operate to the same end. It
is well known that the illustrious Harvey, the discoverer of the circulation, was of the
former opinion, and that he has since been supported by many followers. We admit,
at once, that the heart is the chief organ concerned, but it seems to us equally true that
the arteries also exercise a considerable agency, most commonly as auxiliary to the heart,
yet sometimes to a certain extent independently of that organ. These two positions
are demonstrable, both by experiment and fact.

1. It has been proved that the muscular power is inherent in all the arteries of the
body, in the large and small, in the main trunks as well as in the capillary extremities.

2. That the arteries contract with considerable force, the natural and unavoida-
ble effect of which must be, the propulsion of the blood, and the quickening of the
circulation.

3. That the circulation has been maintained in the foetus, though utterly destitute of
a heart. Cases of this description are recorded in sufficient number, to put the fact be-
yond a doubt. It may, however, be alleged, that in these instances, as very often hap-
pens in the history of the animal economy, the want of one organ is supp ied by the as-
sumption of new, or increased powers by some other. We do not perceive much force
in this objection, but as it might be raised, we will appeal to other facts of a less dis-
putable nature, such as are afforded by the phenomena of local inflammation, active
haemorrhages, blushing, hectic suffusion, and many more which it would be easy to
enumerate. Enough, however, have been mentioned, to show that the circulation may
be increased in a particular part without its being generally affected, and consequently
that the heart is not the only power which propels the blood, but that this force also
resides, in a limited degree, in the arteries. — Chapman.

152

creases, as, at a distance from the heart, the canals along' which it circtt*
lates, increase in number; and lastly, the deviations which the blood
meets with in its course, from the trunks into the branches which,
coming off sometimes, almost at right angles, divert it from its original
direction.

Several physiologists have called in question this progressive slacken-
ing of the flow of arterial blood, and several among them, who reject en-
tirely the application of the physical sciences to that of the animal econo-
my, have, nevertheless, supported their opinion by a fact taken from hy-
draulics. To give any certainty to these calculations, respecting the
impediments to the circulation of the blood in the arteries, it would, they
say, be necessary, that the arteries should be empty at the instant when
they receive the jet of blood sent into them by the contraction of the
ventricles. This, however, is not the case ; the arteries are always full,
the blood flows along all of them with the same degree of velocity. This
system of vessels may be compared to a syringe, from which a number of
straight and tortuous tubes should arise; each of these would throw out
the fluid with an equal degree of velocity, on applying pressure to the
piston.

In refuting this doctrine, I must take notice of the manifest contradic-
tion of pretending to exclude, absolutely, all application of the principles
of mechanics tp physiology, and the complete application of these princi-
ples to the phenomena of the animal economy. This contradiction, how-
ever, is not more surprising than that of authors who exclaim against the
abuse of modern nomenclators, and who, nevertheless, eagerly embrace
every opportunity of adding to it, by assigning new names to such parts
as may have escaped the attention of the new nomenclators. What re-
semblance is there, between a forcing pump, whose sides are unyielding,
as well as those of the tubes which might arise from it, and the aorta which
dilates every time the blood is sent into it; and again, what resemblance
is there, between tubes which decrease towards their open extremities,
\vhilethespacecontained in the arterial tube constantly enlarges, from
the innumerable divisions of the vessels. Since it is admitted, that the
coarse of the blood is slower in the capillary vessels, must not this re-
sistance, opposed to the blood which fills the series of vessels from the
capillaries to the heart, be felt more at a greater distance from that organ,
&c.? Without this progressive increase of resistance, as the arterial
blood is at a greater distance from the heart, this fluid would flow along
the arteries, as it does along the veins without any pulsations ; for, this
resistance, which causes the lateral effort of dilatation effected by the
blood on the parietes of the arteries, is the principal cause of the pulse,
which belongs only to that set of vessels. A very remarkable difference
is observable, between the blood which is sent to the toes, and that which
goes to the mammae, as I have several times noticed in removing the cu-
rious bones of the toes, or in extirpating cancerous breasts : the small ar-
teries of these parts are nearly of the same size, but the jet of blood is
much more rapid, the blood is sent to a much greater distance, when one
of the mammary arteries is divided.

The re-action of the arteries on the blood which dilates them, depends
not only on the great elasticity of their parietes, but likewise on the con-
tractility of the muscular coat. Elasticity has a considerable share in the
action of the larger trunks, while contractility is almost the sole agent,
in producing the action of the minute arteries. If a finger is introduced

153

into the artery of a living animal, its parietes compress it in every direc-
tion ; if the blood is prevented from flowing in it, the canal becomes
obliterated by the adhesion of its parietes* and the vessel is converted
into a ligamentous cord, such as that formed in the adult, by the remains
of the umbilical arteries and veins. This contractility which, during
life, is always in action, keeps the arteries, distended by the blood which
fills them, of a smaller calibre, than after death. In performing capital
operations, especially in the amputation of limbs, I have always found the
arteries, whether filled with blood or empty, much smaller than I should
have expected from their appearance in the dead body.

It happens, however, sometimes, that the quantity of blood sent to an
organ increases, in consequence of some cause of irritation; the calibre
of the arteries of the part, then becomes remarkably enlarged. Thus,
the arteries of the uterus, which are very small in its unimpregnated
state? acquire, towards the end of pregnancy, a calibre equal to that of
the radial artery*, the small arteries which are sent to the mammae, are
not in the same condition, as I have had the opportunity of ascertaining
in a woman who had been sucking a child for two months before her
death; they retained their almost capillary minuteness, which would
seem to prove, that the lymphatics are alrme cQnru?merl in bringing to
these glands the materials of their secretion. The mammary arteries
evidently enlarged in an open cancer of the breast; in cancer of the pe-
nis, the blood-vessels likewise become enlarged; hence in removing the
penis for that affection, it is absolutely necessary to secure the arteries
with ligatures, a precaution which need not be attended to in a case of
gangrene. Gangrene is attended with this peculiarity, that the arteries
of the mortified parts contract, so as to become obliterated, when their
calibre is inconsiderable.

As the arteries are the canals which convey to all our organs the ma-
terials of growth and reparation, they are larger, in proportion, in child-
ren, in whom nutrition is more active, and their calibre is always propor-
tionate to the natural or morbid developement of organs : hence the de-
scending aorta and the iliac arteries are larger in women than in men;
hence the right subclavian artery, which conveys blood to the larger and
more powerful of the two upper extremities, because being more em ployed,
it is larger than the left subclavian. But the effect should not be mistaken
for the cause, and it should not be imagined, that the right upper extre-
mity owes its superiority to the greater calibre of its artery. In the new-
born child, this vessel is not larger than the left subclavin : but the right
arm being more frequently employed, the distribution of the fluids takes
place more favourably, nutrition is carried on with more energy, it ac-
quires more bulk and strength, and therefore the right subclavian artery
conveys blood to it by a wider channel. If the left upper extremity
were employed in the same manner, and if the right were kept in a state
of inaction, the left subclavian would, no doubt, exceed the right. I am
warranted by two facts in forming this conjecture. lu dissecting the bo-
dies of two men that were left-handed, I observed in the left subclavian
arteries, the same proportionate enlargement which is usually met with in
the same vessels on the right side.

* This increase of size in the arteries of the gravid uterus, is a proper growth of parts,
not an accidental dilatation* — Gadman.

U

154

LVIII. As the arteries are always full during life, and as the blood
flows along them with less velocity, the greater their distance from the
heart, the blood which the contractions of the left ventricle send into the
aorta, meeting the column of blood already in that vessel, communicates
to it the impulse which it has received; but retarded in its direct progres-
sion, by the resistance of that column, it acts against the parietes of the
vessels, arid removes them to a greater distance from their axis. This
lateral action which dilates the arteries, depends, therefore, on the resist-
ance of the parietes of these cavities, always filled with blood, to that
which the heart sends into them. This dilatation, which is more consi-
derable in the large arteries than in the smaller ones, manifests itself by
a beat, known under the name of puke*. The experiments of Lamure
would lead one to believe, that another cause of this phenomena is a
slight displacement of the arteries, every time they dilate. These dis-
placements are most easily observed at their curvatures, and where* they
adhere to surrounding parts, by a loose and yielding cellular tissue.

The pulse is more frequent in women, in children, in persons of small
stature, during the influence of the passions, and under violent bodily ex-
ercise, than in an adult man, of high stature, and of a calm, physical, and
moral nature. At an early period of life, the pulse beats as often as a
hundred and forty times in a minute. But as the child gets older, the
motion of the circulation slackens, and at two years old, the pulse beats
only a hundred times, in the same lapse of time. At the age of puberty,
the beats of the pulse are about eighty in a minute; in manhood, seventy-
five ; and lastly, in old men of sixty, the pulse is not above sixty. It is
slower in the inhabitants of cold, than in those of warm climates.

Since the time of Galen, the pulse has furnished physicians with one
of their principal sources of diagnosis. The force, the regularity, the
equality of its pulsations, opposed to their weakness, inequality, irregu-
larity, and intermittence, afford the means of judging of the nature and
danger of a disease, of the power of nature in bringing about a cure, of
the organ that is most affected, of the time or period of the complaint,
Sec. No one has been more successful than Bordeu,in the consideration
of the pulse, under these different points of view. Its modifications in-
dicative of the periods of diseases, establish, according to that celebrated
physician, as may be seen in his Recherches sur le fiouls par rapfiort aux
crises, the pulse of crudity, of irritation, and of concoction. Certain ge-
neral characters indicate, whether the affection is situated above or be-
low the diaphragm, hence the distinction of superior and inferior fiulse.
Lastly, peculiar characters denote the lesion of peculiar organs; which
constitutes the nasal, guttural, pectoral, stomachic, hepatic, intestinal,
renal, uterine, Sec.

Besides these sensible beats, which constitute the phenomenon of the
pulse in the arteries, there is an inward and obscure pulsatory motion, by
which all the parts of the body are agitated, every time that the ventri-
cles of the heart contract. There is a kind of antagonism between the
heart and the other organs, they yield to the impulse which it gives to
the blood, dilate on receiving this fluid, and collapse when the effort of
contraction is over. Every part vibrates, trembles, and palpitates within

* See APPENDIX, Note S, for a different explanation of this phenomenon from that
given by Richerand.

155

the body, the motions of the heart shake its whole mass, and these qui-
verings, which may be observed externally, are most manifest when the
circulation is carried on with rapidity and force. In some head-jches,
the internal carotid arteries pulsate with such violence, tJutt nut only the
ear is sensible to the noise made by the column of blood striking- against
the curvature of the osseous canal, but the head is evidently moved and
raised, as it were, at each pulsation. If you look at your hand or foot,
when the upper or lower extremity is quiescent and pendulous, you will
observe in it, a slight motion corresponding to the beats of the heart.
This motion increases, and even makes the hand shake, when, from the
influence of the passions, or from violent exercise, the circulation is ac-
celerated; in every violent emotion, we feel, within ourselves, the effort
by which the blood, at each beat of the pulse, penetrates into our organs,
and fills every tissue. And it is, in a great measure, from this inward
tact, that we are conscious of existence. A consciousness the more lively
and distinct, as the effect of which we are speaking is more marked. It
is, likewise, from observing this phenomenon, that several physiologists
have been led to conceive the idea of a double motion, which dilates or
condenses, which contracts or expands, alternately, all organs endowed
with life ; they have observed, that dilatation prevails in youth, in inflam-
mation and erection, conditions of which all parts are capable, according
to their difference of structure.

LIX. At the moment when the left ventricle contracts, to send the
blood into the aorta, the sigmoid valves of that artery rise, and apply
themselves to its parietes, without, nevertheless, closing the orifices of
the coronary arteries, which lie above the loose edges of the valves; so
that the blood is received into these vessels, at the same time as into the
others. When the contraction of the ventricle is over, the aorta acts on
the blood which it contains, and would send it back into the ventricle, if
the valves, by suddenly descending, did not present an insuperable obsta-
cle to the return of blood, and did not yield a point of resistance to the
action of the whole arterial system ; only the small quantity of blood be-
low the valves, at the moment of their descending, flows back towards
the heart, and returns into the ventricle,

Though the rate at which the blood flows along the aorta, has been
estimated at only about eight inches in a second, a pulsation is felt in all
the arteries of a certain calibre, at the instant the ventricles are contract-
ing. The reason that the pulsations of the heart appear to take place, at
the same time as those of the arteries, is, that the columns of blood, in
these vessels, receive an impulse from that which is issuing from the* ven-
tricles, and this concussion is felt in an instant of time, too short to be'
measured, such as that which is felt by the hand applied to the end of a
piece of timber struck, at the other end, with a hammer. The blood
which fills the main trunk, supplies to each of the branches which arise
from it, columns proportionate to their calibre. This division of the
principal column is effected by a kind of projection at the mouth of each
artery. These internal projections detach from the main stream, the
lesser ones, and these flow the more readily into the branches, according
as these arise from the trunk, at a more acute angle, as the projection is
more prominent, and the deviation of the fluid less considerable. If the
branches are given off, at an almost right angle, the orifices of the arte-
ries scarcely project at all, and nothing but the effort of lateral pressure;
determines the flow of the blood into them.

156

The flow of the blood into the arteries which are distributed to mus-
cles, is not interrupted, when these muscles contract, for, whenever arte-
ries, of a certain calibre, penetrate into muscles, they are surrounded by
a tendinous ring1, which, during the contraction of the muscle, becomes
enlarged, from the extension in every direction, effected by the fibres
which are attached to it, around its circumference. The existence of
this truly admirable conformation, may be readily ascertained, by observ-
ing the aorta, in its passage through the crura of the diaphragm; the
perforating arteries of the thigh, where they enter at the back part of the
limb into the adductor muscles, the popliteal, as it passes through the
upper extremity of the soleus muscle.

LX. Of the capillary -vessels. The arteries, after dividing into branches,
these branches into lesser ones, and these into progressively smaller
ramifications, terminate in the tissue of our organs, by becoming conti-
nuous with the veins. The venous system arises, therefore, from the ar-
terial system, the origin of the veins being merely the more minute ex-
tremities of the arteries, which becoming capillary from the great number
of divisions* they have undergone, bend in an opposite direction, and
become altered in their structure.

These minute capillary arteries form with the minute veins, with which
they are continuous, and with the lymphatics, wonderful meshes in the
tissue of our organs.

Several physiologists consider the capillary blood-vessels as an inter-
mediate system between the arteries and veins, in which the blood, en-
tirely out of the influence of the action of the heart, flows slowly, with an
oscillatory and sometimes retrograde motion, is no longer red, because
its globules are strained, as it were, and, in a manner, lost in a colourless
serum, which serves them as a vehicle.

It is, in fact, necessary, that bodies should be of a certain bulk, to re-
flect the rays of light at an angle sufficiently obtuse, that the eye may dis-
cover their colour. We know, that grains of saiid reduced to a very fine
dust, appear colourless, when examined separately, and are seen to pos-
sess colour, only when in a state of aggregation : further, very thin lami-
na of a horny substance, appear transparent, though the part from which
they have been detached be of a red or blue colour. But if several of
these transparent lamina be laid on one another, the red colour becomes
darker, in proportion as a greater number are brought together.

Let irritation, from whatever cause, determine the blood to flow into
the serous capillary vessels, in greater quantity, and with more force,
these vessels will become apparent, the "organs in whose structure they
circulate, will acquire a red colour, more or less deep; thus the conjunc-
tiva, the pleura, the peritoneum, the cartilages, the ligaments, &c. which
naturally, are whitish or transparent, become red, when affected with
inflammation, whether from the increased impetus of the circulation,
which forces and accumulates into the capillary vessels, a greater num-
ber of red globules, or that the sensibility of these small vessels is im-

* The arterial divisions which may be discerned by the aid of anatomy, do not ex-
ceed eighteen or twenty : nevertheless, they divide still further, when they are become
so minute us not to be discernible without the help of the most powerful microscope,—'

Note.

157

paired by inflammation, so that they admit globules which they formerly
rejected.

Some capillary vessels transmit blood at all times, and uniformly ex-
hibit a red colour : this is the case with the capillary vessels of the spleen,
of the corpora cavernosa of the penis, of the bulb and corpus spongiosum
of the urethra: the same applies to the capillaries of the muscles of the
mucous membranes : there arc, however, very few of those organs, in
v/hich the whole portion of the capillary tube, between the termination of
the artery and the origin of the vein, is filled with red blood. There is,
almost always, a division in the tortuous line described by the capillary,
and within this space, the blood cannot be detected of its usual colour*.

The number of the capillary vessels, as well as that of the arteries,
to which the former are as auxiliaries, is much more considerable in the
secretory organs, than in those in \$hich life carries on only the process
of nutrition. It is on that account, that the Ijones, the tendons, the liga-
ments, the cartilages, contain so much smaller a quantity of blood, than
the mucous and serous membranes, and the skin. The capillary vessels
are, however, very numerous, in the muscles, which owe that colour to
the great quantity of blood they contain, but as we *hall point out, when
we come to speak of motion, this fluid appears to form an essential ele-
ment in muscular contraction; it is, therefore, not to be wondered, that
these organs should have a greater number of capillary vessels sent to
them: since these vessels do not supply them merely with molecules to
carry on nutrition, and to repair the waste of the part, but to impart to
them the principle of their frequent contraction ; the quantity of them is
so considerable, in all these parts, employed in the two-fold offices of nu-
trition and secretion, that Ruysch penetrated, with his injections, the
whole thickness of their substance, to such a degree, that the organs which
he had prepared, were only a wonderful and inextricable net-work of ca-
pillary vessels extremely minute. On these anatomical preparations,
made with an art hitherto unrivalled, Ruysch grounded his hypothesis
relative to the intimate structure of the body, in which, he imagined, all
was capillary tubes, an hypothesis which has obtained the most favoura-
ble reception, and has reigned, during more than a century in the schools.
It is enough to reflect a moment on their uses, to conceive that the num-
ber of them must be really prodigious. As long as the blood is enclosed
within the arteries, and flows under the contrcul of the heart, it fulfils no
purpose either of nutrition or secretion. To make it subservient to these
great functions, it must be diffused through the very tis:,u< of the organs,
by means of the capillary divisions; these little vessels exist then, in every
part, where any organized molecules are found united ; since the parti-
cle formed by their assemblage, must, at least, find, in the juices which
they bring to it, the materials of its reparation. Entering, in greater or
less proportion, into the organization of all the tissues, the capillaries re-
ceive certain modifications from the organs of which they are an integral
part; modifications which enable them to deposit the serous part of the
blood on the surface of the serous membranes, admit the transudation of

* There is every reason for concluding that capillary vessels exist, which, running-
between some of the terminations of the arteries and the commencement of veins, ad-
mit only the serous portion of the blood, when performing- their healthy functions ; but
which may, in a state of inflammation, admit also the red particles of this fluid to flow
along them. — Copland

158

the fat into the cells of the cellular tissue, furnish the urine tp the kid-
neys, and the liver with the materials of the bile : in a word, suffer to es-
cape, through the porosities with which their pa^ietes are pierced, the
principles which the blood has to furnish to every organ.

It is by these lateral porosities, and not by extremities open on all the
surfaces, and in all the points of the organs, that the capillaries transpire,
in some sort, the elements of nutrition, and of the various secretions*.
Mascagni was aware, that Nature, skilful in deducing many effects from
few causes, has not deviated, in the construction of the system of circu-
lation, from the invariable laws of her ordinary simplicity; but the lateral
pores of the capillaries, which are sufficient for the explanation of all the
phenomena ascribed to the exhaling mouths of the arteries, and to the
pretended continuity of these vessels with the excretory ducts of the or-
gans, Sec. are not openings like the |)ores common to all matter; each of
them may be considered as an orifice, sensible, and, especially contractile,
of differing size, according to the state of the strength, or of the vital pow-
ers. The size then of these capillary pores is subject to frequent varia-
tions; and this is the explanation given of the formation of scorbutic ec-
chymoses, of petechiae, of passive or relaxed hemorrhages. In all these
affections, contractility being really diminished, the pores of the capilla-
ries enlarge, and suffer the red blood to transude through their relaxed
mouths. This phenomenon takes place, not only under the skin and on
the various mucous surfaces, it is observed also in the very tissue of the
organs. It is thus, that I have often seen, on opening the bodies of those
that had died of the scurvy, in its last stage, the muscles of the leg filled
with blood. This sort of interior hemorrhage, converts the muscles into
a kind of pulp; and the extravasated blood itself undergoes a beginning
of decomposition. 'I he bones themselves are liable to these scorbutic
bloody nitrations. I had an opportunity of ascertaining this in the Hos-
pital of St. Louis, at the same time that I learnt the difficulty of procuring
a durable skeleton from such bodies. The greatest number die, in a very
advanced stage of the disease, and the bones dissolve in maceration, or
rot in a very little time.

The capillary vessels, whether the blood flow through them red, or
colourless, are not a system of vessels distinct from that of the arteries,
and from that of the veins: they belong essentially to these two orders of
vessels. Those which, ramifying in the tissue of the skin, or of the se-
rous membranes, suffer the serum of the blood to transude, are not more
entitled to the name ofexhalent system, which some authors have given
them. To consider a? distinct and insulated systems, separate parts of a
system of organs, is to incumber science with a crowd of divisions, as
false as they are useless.

LXI. The sanguineous capillaries anastomose, and form, like the lym-
phatic capillaries, a net-work that envelopes all the organs. Their fre-
quent communications do not allow obstructions to take place, and to
produce inflammation, as Boerhaave thought, and as was long taught, on
the authority of that celebrated physician- Haller, Spallanzani, all the
microscopic observers, have perceived threads of blood flowing in the ca-
pillaries, offering themselves at the various inosculations of these vessels,

* See APPENDIX, Note S, for observations on the functions of the capillary system ;
Jtnd on nutrition.

159

and have seen them flow back, when they were not admitted, to seek other
easier entrances.

I will not collect, in this place, superfluous arguments against the
theory of the Leyden professor, rejected at its birth by the physicians of
Montpellier, absolutely refuted, and now universally given up. Irritation
alone keeps the blood in the inflamed part ; for, when death, which puts
an end to all irritations, and relaxes all spasms : when I say, death comes
on, all slight inflammations are dissipated, and whenever they have not
been sufficiently intense, to induce transudation of the blood through the
parietes of the capillaries, into thecrco/a? of the organic tissues, the blood
flows back into the large vessels, and there is no trace of it left. It is thus,
that erysipelas of the skin disappears, that the pleura preserves its trans-
parency, in individuals affected, before death, with sharp pains in the
side. If to this, we add our ignorance on the real organization of the
nervous system, on the conditions absolutely required of the brain and
nerves, for the maintenance of life, we shall cease to be surprised, that the
opening of bodies has taught us no more on the real seat of disease, and
we shall confess with Morgagni, who, however employed, with great suc-
cess, this means of improving the art of healing, that there are number-
less diseases, of which, after death, no trace is left, and for the fatal ter-
mination of which, we are unable to account.

Contractility and sensibility exist, in a much higher degree, in the ca-
pillary and serous vessels, than in the veins and arteries. Life must needs
be more active in the former, for, the motion given to the blood by the
contractions of the heart, being exhausted, this fluid, no longer in the
sphere of action of that organ, can circulate, viutfrom the influence of the
action of the vessels themselves.

The termination of the arteries in veins, is the only well ascertained
termination of those vessels ; it may be seen by the help of the micro-
scope, in cold-blooded animals, in frogs and salamanders. In some fish,
\ve may, even with the naked eye, observe frequent and considerable
inosculations, between the arteries and veins. In man, however, and in
other warm-blooded animals, these communications take place, only
at the extremities of the two systems of vessels. In this case, the arte-
ries terminate, sometimes, in capillary vessels carrying serous fluid, such
as the vessels of the sclerotic coat; these vessels become small veins
whose calibre gradually increases, until they admit red globules in suf-
ficient number to reflect that colour. At other times, the artery and vein
are continuous, without the intervention of that extremely minute sub-
division: the red blood then passes readily and immediately from the ar-
tery into the vein*.

It will be shown, in speaking of secretion, that the continuation of the
arteries into the excretory ducts of the conglomerate glands, and their
termination in exhaling orifices, cannot be admitted, and that the presence
of small pores, in the sides of the minute arteries and veins, would afford
an explanation of the phenomena on which the belief of this termination
of the arteries rests. There exists no parenchyma, no spongy tissue, be-
tween the extremities of the arteries and the origin of the veins, with,
perhaps, the exception of the substance of the cavernous bodies of the

* See the Chapter on the Organs of Generation.

160

penis and of the clitoris, of the bulb and spongy part of the urethra*,, the
retiform plexus, which surrounds the orifice of the vagina, and, perhaps,
also, the tissue of the spleen, though the experiments of anatomists (Mas-
cagni and Lobstein) seem to prove, that in these organs, the arteries and
veins, are immediately continuous!.

LXIL Of the action of the veins\. These vessels, whose functions it is
to carry back to the heart, the blood which the arteries have sent to all
the organs, are much more numerous than the arteries themselves. It is
observed, in fact, that arteries of a middle size, as those of the leg a^
fore-arm, have each two corresponding veins, whose calibre, at leS^
equals theirs, and that there is besides, a set of superficial veins, lying
between the skin which covers th*> limbs and the aponeuroses which en-
velope the muscles: these have no corresponding arteries. The space
which the venous blood occupies is, therefore, much greater than that
taken up by the blood in the arteries. Hence also, it is estimated, that of
twenty-eight or thirty pounds of this fluid,, making about a fifth part of the
whole weight of the body in an adult man, nine parts are present in the
veins, and only four in the arteries. In this calculation, one should con-
sider as arterial, the blood contained in the pulmonary veins and in the
left cavities of the heart, while that which fills the cavities in the right
side of the heart and the pulmonary artery is truly venous, and has every
character of such blood.

Although the veins generally accompany the arteries, and are united
to them, by a common sheath of cellular membrane, this disposition of
parts is not without exceptions. The veins which bring back the blood
from the liver, do not, in any respect, foliovv the course of the branches
of the hepatic artery : the sinuses of the brain are very different, in their
arrangement, from the cerebral arteries ; the veins of the bones, which
are particularly numerous, and of a much greater calibre than the arte-
ries of the same parts, from the slow circulation of the blood along them,
do not generally follow the direction of the arteries, and arise singly from
the substance of the bone, with the exception of those in the middle ca-
nal, and which pass through the nutritious foramen of the bone. The
veins are not only more numerous than the arteries, but they are like-
wise more capacious, and dilate more readily; this structure was neces-
sary, on account of the slowness with which the blood circulates, and of
the readiness with which it stagnates, when the slightest obstacle impedes

* See APPENDIX, NoteN.

-f See APPENDIX. Note T.

t In the month of February, 1823, while preparing a subject for the demonstration of
the arteries, I was presented with the most satisfactory evidence of the direct communi-
cation between the arteries and veins. Into the left carotid artery of an adult and ema-
ciated subject, I introduced and secured a large sized pipe, pointing1 towards the chest.
Into this was thrown with the ordinary syringe, melted tallow, highly coloured with
King's yellow. The injection was generally minute, more particularly so in the arms,
and most in that of the left side. In the arms, not only were the arteries filled, but the
veins of the smallest size, from the extremities of the fingers to the axilla, were entire-
ly distended. What was still more interesting, the tallow in the arteries was of a very
bright yellow, increasing in colour as the arteries became smaller, while in the veins the
tallow was entirely destitute of colour, having passed through vessels too small to allow
the colouring matter to accompany it. Wherever a small artery could be seen a vein
filled with the pure tallow could<be distinctly observed.

This injection was demonstrated before a large class, and was shown to several mem-
bers of the Academy of Natural Sciences of Philadelphia. — Godman*

161

its circulation * The force which carries on the circulation of the blood,
along the arteries, is so great, that Nature seems not to have availed her-
self of the mechanical advantages which might have facilitated its flow. On
the other hand, the power which determines the progression of the venous
blood is so feeble, that she has sedulously removed every obstacle which
might have impeded its course; and as the relation of the minute to the
larger branches, of these to the trunk, is the same as in the arteries, two
branches unite to form a vein of greater calibre than each separate ves-
sel, but smaller than the two taken together, the blood flows along a space
which becomes narrower, the nearer it approaches the heart ; the rapi-
dity of its course must, therefore, be progressively increased.

The veins are almost straight in their course ; at least, they are much
less tortuous than the arteries. The force which makes the blood flow
along them, is consequently not taken up in straightening these curves ;
the anastomoses are, likewise, more frequent, and as the flow of the
blood might have been intercepted in the deep seated veins of the limbs,
when the muscles, among which these vessels lie, during contraction,
compress them by their enlargement and induration, they communicate
freely with the superficial veins, towards which the blood is carried, and
flows the more readily, as they are not liable to be compressed. It is
to be observed, and is to be accounted for on the same principle, that the
superficial veins are very large and distinct among the lower orders who
are employed in laborious occupations, requiring an almost continual ex-
ertion of their limbs. Lastly, the internal part of the veins, like that of
the lymphatics, is furnished with valvular folds, formed by the duplica-
ture of their epidermoid coat. These valves, which are seldom single,
and almost always in pairs, are not found in the minute veins, nor in the
great trunks, nor in the veins which bring back the blood from the vis-
cera in the great cavities.

These valves, in falling, close completely the canal of the vessel, de-
stroy the continuity of the column of blood returning to the heart, divide
it into smaller columns, as numerous as the intervals between the valves,
and the height of which is determined by the distance between these
folds. So that the power which carries onward the venous blood, and
which would be incapable of propelling the whole mass, acts advantage-
ously on each of the small portions into which it is divided.

LXIII. It has been thought, that the principal cause which makes the
blood flow into the veins, is the combined action of the heart and arteries;
but the impulse from those organs, is lost in the system of capillary ves-
sels, and does not extend to the veins. The specific action of their own
parietes, aided by auxiliary means, such as the motion of the neighbour-
ing arteries, is sufficient to carry the blood on to the heartf.

* The arteries contain, at all times, nearly the same quantity of blood. The veins
are always the seat of plethora, because the blood stag-nates in them more readily; and
this condition brings an inflammatory fever (consisting' merely in an increased action of
the vascular system, as is expressed by the term ungeioteniqite applied to it by Professor
PineV) only when the venous congestion becoming- excessive, the blood passes with
difficulty from the arteries into the veins. The heart and the arteries then struggle,
with considerable effort, to rid themselves of the fluid which oppresses them, &c. —
Jiuthor't Note.

•{• In the process of returning the blood to the heart, two causes are principally en-
gaged, the most efficient of which is, undoubtedly, the contractile power of the vein$
themselves, AVe are aware that this property is denied to them by many who have

162

These panetes, which are much thinner than those of the arteries, are
contained, like theirs, in a sheath common to all the vessels. Three coats,
likewise, enter into their structure ; the middle or fibrous coat is not very
distinct, and consist merely of a few longitudinal reddish fibres, which can
be distinguished only in the larger veins, near the heart. In some of the
larger quadrupeds, as in the ox, these fibres form distinct fasciculi, and
their muscularity is much more manifest.

The internal coat, which is more extensible that that of the arteries,
and equally thin, adheres more closely to the other coats. The cellular
coat, which connects it to the middle one, is less abundant, hence phos-
phate of lime is seldom deposited into it, as happens to the arteries which
frequently become ossified, as we advance in years. This internal coat is
merely a continuation of that which lines the cavities of the heart; and as
the origin of the inner coat of the arteries is the same, there exists a non-
interrupted continuity in the membrane which lines all the canals of the
circulation. The inner coat forms the only essential part of the venous
system; it alone constitutes the veins within the bones, the sinuses of the
dura mater, the hepatic veins, in a word, all the veins which are so firmly
attached externally to the neighbouring parts, that the blood flows along
them, as along inert tubes, their parietes being, almost completely inca-
pable of contracting.

The veins, in their passage through muscles, are, like the arteries,
guarded by aponeurotic rings, than which is more remarkable than that
which belongs to the aperture in the diaphragm, which transmits the as-
cending cava from the abdomen into the thorax. This vessel is, therefore,
not compressed by the contraction of that muscle in inspiration.

LXIV. As the inferior cava passes through the lower edge of the liver,
whether along a deep fissure, or in a real canal in the parenchymatous
substance of that viscus, the course of the blood must be impeded, when,
from congestion of the parenchyma, the vessel is, in some sort strangu-
lated.

Obstruction of the liver, which is of such frequent occurrence, would
have been attended with fatal consequences, by preventing the return of
the blood from the inferior parts, along the ascending cava, if this great
venous trunk did not keep up, by means of the vena azygos, an open and
free communication with the descending or superior cava. The use of
this anastomosis of the two great veins is, evidently, to facilitate the pas-
sage of the blood from the one of these vessels into the other, when either,
especially the lower, does not readily evacuate its contents into the right
auricle. On this account, the vena azygos is capable of considerable
dilatation, and is entirely without valves. In the body of a man opened,
in my presence, and whose liver was twice as large as in health, I ob-

speculated on the subject. It is, however, shown by Haller, that the vena cava, at
least, is muscular, and Verschuyr and other respectable physiologists, have detected
the same structure in the most minute veins. There is one act which xve think ought
alone to convince us of the contractility of these vessels, which is, that they always
adapt themselves to the quantity of blood they contain.

Co-operating with the above cause is the action of the muscles, as may be illustrated
by the familiar example of venaesection. When in this case the blood issues languidly
from the orifice made in the vein, it is known, that nothing promotes its flow so effec-
tually as pressing something hard in the hand. This operates simply by bringing into
action the muscles of the fore-arm and humerus, thereby producing considerable com-
pression of the veins.— Chapman.

163

served, that the vena azygos, which was distended with blood, was of
the size of the little linger ; the termination downward of this vessel, in
the right renal vein, and above in the superior cava, were most distinct,
and by compressing it from above downward, or from below upward, the
blood flowed into one or the other of these vessels.

As the causes which determine the circulation of the venous blood,
communicate to it an impulse which is far from rapid, and as this fluid
meets with only trifling obstacles, and such as are easily overcome, the
pressure against the parietes of the veins is very inconsiderable, and these
vessels do not pulsate, as the arteries. There is observed, however,
near the heart, an undulatory motion, which the blood communicates to
the parietes of the vessels. These kinds of alternate pulsations depend on
the rapidity with which the blood, whose course is progressively accele-
rated, flows towards the heart, and on the reflux of the blood, during the
contraction of the right auricle. The contraction of this cavity, forces
back the blood into the veins which open into it; this retrograde course
is manifest in the superior cava, and is the more readily occasioned, as the
orifice of this vein is not furnished with any valve that might prevent it.
It does not, however, extend very far towards the brain, the blood having
to ascend against its own weight, and the jugulars admitting of considera-
ble dilatation. This regurgitation is still more marked in the inferior cava,
the orifice of which is but imperfectly closed by the valve of Eustachius ;
it is felt in the abdominal veins, and extends even to the external iliacs, ac-
. cording to the testimony of Haller.

LXV. The orifice of the great coronary being exactly covered over by
its valve, the blood does not return into the tissue of the heart, which
being a contractile organ, would have had its irritability impaired by the
presence of venous blood. It is of consequence to observe, that this re-
flux never extends to the veins which bring back the blood from the mus-
cles, and that it is never felt in the veins of the limbs which are furnished
internally with valvular folds. The case is very different, between our or-
gans of motion and these secretory glands : towards these the blood re-
quired to be sent back, so as to be the longer exposed to their action : ve-
nous blood diminishes and even destroys muscular irritability, and is truly
oppressive, as may be ascertained by injecting some, in the arteries of a
living animal, or else by tying the veins, so as to prevent its return, or
by observing what happens, when the course of the blood is interrupted,
either by applyingfirm ligatures round the limbs, or by wearing confined
clothes.

I am satisfied, that it was from observing the oscillatory undulations of
the venous blood, in the great vessels, that the ancients were led to the
opinions they entertained on the course of the blood, which they com-
pared to the Euripus, whose waves are represented by the poets, as un-
certain in their course, and in currents running in contrary directions.

The internal veins in which this reflux is observed, show this motion of
the blood most distinctly of any; their sides which are thin and semi-
transparent, not being, as in other parts, surrounded by an adipose cellu-
lar tissue. To give a complete notion of the doctrine of the ancients, on
the subject of the circulation, it will merely be necessary to add to the
above idea, the opinion which they entertained, that the chyle taken up
by the meseraic veins, was carried to the liver, in which its sanguification
was effected ; and lastly, that the arteries were filled with vital spirit, and

164

contained only a few drops of biood which passed through small hole&>
which, Galen says, perforate the septum of the ventricles.

The blood, however, continually urged on by the columns which fol-
low each other in succession, by the action of the veins whose parietes
become gradually stronger, and by the compression which these vessels
experience from the viscera, during the motion of respiration, reaches
the heart, and enters the auricles with the greater facility, as the
orifices of the cavae not being directly opposed to each other, the co-
lumns of blood which they convey, do not meet, and do not oppose each
other.

LXVI. The blood continually carried to all parts of the body by the
arteries, returns, therefore to the heart, by a motion which can never be
interrupted, without considerable danger of life. We know that the cir-
culation is thus effected, from the direction of the valves of the heart, of
the arteries and veins; by what happens, when these vessels are opened,
compressed, or tied, or when a fluid is injected into them. When an
artery is wounded, the blood comes from the part of the vessel nearest
the heart: it comes, on the contrary, from towards the extremities, if it
is a vein that has been opened. By compressing or tying an artery, the
course of the blood is suspended below the ligature, and the vessel
swells above. The veins, on the contrary, when tied or compressed, di-
late below. Lastly, when an acid fluid is injected into a vein, the blood
is seen to coagulate in the direction of the heart. By the help of the mi-
croscope, we may see in the semi-transparent vessels of frogs and other
cold-blooded animals, the blood flowing from the heart into the arteries,
and from these into the veins, which return it to the heart. It was on
the strength of these convincing proofs, that William Harvey established,
towards the middle of the seventeenth century, the theory of the circula-
tion qf the blood. Its mechanism had rather been guessed at, than un-
derstood, by several authors. Servetus and Cesalpinus appear to have-
been acquainted with it*; but no one has more clearly explained it than
the English physiologist, who is justly considered the author of that im-
mortal discovery.

LXVII. The theory of Harvey, such as it is laid down in his work,
entitled, De sanguinis circuitu^ extrcitationes anatomicx, does not appear
to roe entirely admissible. He considers the heart as the only agent
which sets the blood in motion, and does not take into account the action
of the veins and arteries, which he considers as completely inert tubes,
while every thing tends to prove that the arteries and veins assist the mo-
tion of the blood by an action peculiar to themselvesf. He admits, that
the blood flows in every part of the circulatory system, with an uniform
degree of speed; an opinion so manifestly contradicted by reasoning and
experience, which prove that the velocity of its course diminishes, the
greater its distance from the heart, from the influence of a great number
of circumstances, which it would be useless to repeat (LV1I.) This
doctrine has yet, however, several abettors, and among the moderns,
Spallanzani has endeavoured to support it, by a number of experiments

* Their " acquaintance" with the circulation was nothing better than mere guessing.
The passages of their works referring to this subject, maybe seen in the introduction
to Harvey — Godman.

j See APPENDIX* Notes A, B, S, T.

165

so contradictory, that one is surprised that so judicious a physiologist
should have collected them to establish a theory completely refuted by
several of them. Nothing, for example, contradicts it more fully, than
the continuation of the flow of the blood, in the vessels of frogs and sa-
lamanders, after the hearts of these reptiles have been torn out: there
are, besides, animals which, not possessed of that central organ, have
nevertheless, vessels along which the blood flows, and which contract
and dilate, by alternate motions.

If the mere force of the heart propelled the blood to every part, the
course of this fluid ought, at intervals, to be suspended, its circulation,
at least, ought to be slackened, when the ventricles cease to contract;
but as the contraction of the arteries corresponds to the relaxation of the
ventricles, these two powers, whose action alternates, are continually
employed in propelling the blood along its innumerable channels.

Besides the general circulation, of which the laws and phenomena
have just been mentioned, each part may be said to have its peculiar
mode of circulation, more or less rapid, according to the arrangement
and structure of its vessels. Each of these individual circulations forms
a part of the machinery included in the great circle of the general circu-
lation, and in which the course of the blood takes place in a different
manner, may be accelerated or retarded, without affecting the general
circulation. Thus, in a whitlow of a finger, the radial artery pulsates
a hundred times in a minute, while on the sound side, its beats are only
seventy in number, and perfectly isochronous with the pulsations of the
heart*. In the same manner, the blood of the intestines, which is des-
tined to furnish the materials of bile, flows much more slowly than that
of other parts.

These modifications affecting the velocity of the circulatory motion of
the blood, account for the difference of its qualities in different organs;
all these differences form a part of the plan of nature, and it is not difficult
to understand their utility.

LXVIII. In what has been said of the circulation, no separate mention
has been made of the course of the blood through the lungs, called by
authors the lesser or pulmonary circulation. The vascular system of the
lungs, with the addition even of the cavities of the heart which belong to
it, does not represent a complete circle, it is only a segment, or rather
an arch of the great circle of general Circulation.

The blood, in going along that great circle, meets with the organs,
situated like so many points of intersection in the course of the vessel
which form that circle.

To render still more simple, the idea which is to be entertained on the
subject, one may reduce these intersections to two principal ones; the
one corresponding to the lungs, the other to the rest of the body; the
veins, the right cavities of the heart, and the pulmonary artery with its

* This assertion is altogether too roundly made, and appears rather to be one of
those things which are received as true from having been often repeated, than the ac-
curate detail of a well observed fact. That there may be a difference in the degree of
dilatation and force of pulsation in different arteries is well known, and may depend on
the peculiar condition of the nerves supplying the affected vessels, but that one radial
artery should beat one hundred strokes in "a minute, while the other beats but seventy*
presupposes the existence of a power in the arteries themselves which has never yet
been fnwed, however often it may have been supposed. — Godmafi,

166

divisions, forming one-half of the circle; the pulmonary veins, the left
cavities of the heart, the aorta with all its branches representing the
other half. The capillary vessels of the lungs form one of the points of
intersection, and the capillaries of all the other organs, represent the other
point of intersection, by uniting together the arteries and veins of the
whole body, in the same manner as those of the lungs establish a com-
munication between the veins and arteries of these organs.

This division of the system of circulation into two parts, in one of which
there circulates a dark or venous blood, while the other contains red or
arterial blood, is at once more simple and more accurate. As was alrea-
dy stated, in the history of the circulation, that its organs are, in an espe-
cial manner destined to the mechanical act of conveying the fluids: the
changes, the alterations which the blood undergoes in passing through
the organs, are affected, only at the moment when in penetrating into
their tissue, it passes into the capillary vessels which are distributed
into them. The columns of blood are then sufficiently minute, to be
operated upon by the vital action; till then, the columns of blood are too
large, and resist, by their bulk, if one may so speak, any decomposition.
It is, therefore, in the capillary vessels, that the blood receives its essen-
tial principles; and to understand how the nutritious lymph which is
deposited by the thoracic duct in the left subclavian vein, experiences,
in its course along the sanguiferous system, the changes which are to
assimilate it to our own substance, it is necessary to follow it, along the
venous blood with which it unites, into the heart, through the right half
of which it passes in its way to the lungs, there to combine with the at-
mospherical air, from which we are perpetually deriving another aliment
indispensable to life; then to examine, how, when modified and conveyed
with the red blood, from the lungs to the whole body, it serves to the
secretions, and supplies nourishment to the whole body.

In considering, in this manner, the circulation of the blood, with a re-
ference to the changes which it undergoes in the organs through which
it passes, in describing that circle, we shall find, that this fluid, already
combined with the lymph and chyle, parts, in the lungs, with some of its
principles, at the same time that it becomes impregnated with the vital
portion of the atmosphere, which suddenly changes its colour and other
qualities. The blood will then be seen to flow into a!l the parts which it
stimulates, to keep up their energy, to awaken their action, and furnish
them the materials of the fluids which they secrete, or the molecules by
which they grow or are repaired; so that in supplying thus the different
organs, the blood loses all the qualities which it had acquired by the union
of the chyle and of the vital air, parts with the principles to which it
owed its colour, and again becomes dark, to be repaired anew by com-
bining with the lymph, and by the absorption of the vital part of the at-
mospherical air*: this constitutes the principal phenomenon of the func-
tion, which will be considered in the fourth chapter.

* See the Notes on Respiration, in the APPENDIX, for a different opinion.

167

CHAPTER IV.

OF RESPIRATION.

LXIX. OF the different changes which the blood undergoes in the
different organs, none are more essential or more remarkable than those
it receives from the air, which, during respiration, is alternately received
into the lungs, and expelled from them. The blood which the veins
convey to the heart, and which the right ventricle transmits to the lungs,
is of a dark colour, and heavy: its temperature is only thirty degrees
(Reaumur's thermometer;) if laid by, it coagulates slowly, and there is
separated from it a considerable quantity of serum. The blood which is
brought by the pulmonary veins to the left side of the heart, and which
is conveyed to all parts of the body, by means of the arteries, is, on the
contrary, of a florid red colour; it is spumous, lighter, and warmer by
two degrees. It likewise coagulates more readily, and contains a smaller
quantity of serum. All these differences, which are so easily distin-
guished, depend on the changes which it has undergone, by being in
contact with the atmospherical air.

LXX. Of the Atmosphere. The mass of air which surrounds the globe,
and to which we give the name of atmosphere, bears on all bodies with
a pressure proportioned to their surface. That of man* bears a weight
of air amounting to about thirty-six thousand pounds. Moreover, one of
its constituent principles is absolutely necessary to the keeping up of
life, of which it is a principal agent.

The variations in the weight of the atmosphere have, in general, but
little influence on the exercise of the functions; nevertheless, when by
ascending the tops of very high mountains, man rises several thousand
fathoms above the level of the sea, the very remarkable diminution of
the weight of the air, produces a very sensible effect. Respiration be-
comes laborious and panting, the pulse is quickened, and there is felt an
universal uneasiness, joined to excessive weakness, and haemorrhages
come on: these symptoms are occasioned both by the diminished pres-
sure of the air, and by the smaller quantity of oxygen contained in a
rarer atmospheref.

* The surface of the body is estimated at fifteen or sixteen square feet, in a man of
middle size.

f Several travellers, whose reports on the subject I have consulted, agree in repre-
senting the corporeal, as well as some of the mental functions, to be very strangely in-
fluenced by a rarified condition of the atmosphere. But the celebrated be Saussure, a
writer, who unites to the profundity of philosophical research, the polish of literary re-
finement, has from personal experience described these affections with the most pre-
cision. To his description, I shall, therefore, principally adhere in the ensuing1 inquiry.

He states, that at a certain height above the level of the sea, there uniformly takes
place a sudden and uncommon exhaustion of the muscular power. The natives of the
Alps, who can climb for hours at the foot of the mountains without being at all wea-
ried, are forced TO stop, and take breath every few minutes, when they ascend the

168

The human body resists, without any effort, the atmospherical pres-
sure, because it is applied at all times, and in every direction. But if
a part of its surface ceases, for a moment, to be under its influence, it
swells, the fluids are determined to it, in considerable quantity, the in-
teguments become excessively distended, so as to be in danger of burst-
height of fourteen or fifteen hundred toises. Those who are less accustomed to the
air of the mountains, are obliged to rest much more frequently. So intolerable, indeed,
is the fatigue induced in this situation, that the person suffering it, is rendered some-
times wholly incapable of motion. If he attempt to move, his legs sink under him, his
heart palpitates, his arteries throb, his head becomes g'iddy, his eyes are dazzled, and,
to avoid fainting, he is forced to sit doww. Near the top of Mont Blanc, our traveller
could not advance more than a few steps without stopping to respire, and on the sum-
mit of it, though his exertions were moderate, he was constrained frequently to desist
altogether from them, and breathe laboriously to recruit his strength. With this exces-
sive degree of fatigue, accelerated pulse, and difficult respiration, there is great thirst,
sickness of stomach, a loathing of food, and an aversion to every species of spirituous
liquor. But what is very extraordinary, these affections are as short in their duration,
as they are violent.

These effects are not peculiar to the human species. The same writer relates, that
the mules which tie employed to carry his baggage, became suddenly so weak and ex-
hausted that they could hardly walk, even when the burden was removed from their
backs. They staggered as they moved ; their respiration was panting and difficult, and
seemingly attended with painful sensations of the chest, as they uttered plaintive and
distressing cries.

After resting a few minutes, the sense of fatigue is so completely dissipated, tbat the
person, in resuming his journey, feels such a renovation, that he is persuaded he will
be able to prosecute it uninterruptedly. He, however, is soon disappointed. On
moving a short distance only, his former inability returns, and his progress is again ar-
rested. An additional effect of this state of the atmosphere, is an almost irresistible
propensity to sleep. We are told, that if the attention of the person be not engaged,
and kept excited, he will, wh<>n pausing to rest, often fall to sleep almost instantane-
ously, though annoyed by the wind or cold, the light or heat of the sun, and in the
most incommodious and disagreeable posture of his body. This sleep sometimes, ap-
proaches in soundness nearly to lethargy. It may also be observed, that aeronauts have
generally mentioned drowsiness as one" of the consequences produced by the attenu-
ated atmosphere of the exalted regions which they explore in their excursive flights,
and some have even declared that they slept soundly, when at the utmost pitch of their
perilous adventures.

Nothing affords the least relief to any of the symptoms enumerated, except rest and
cold -water. Cordials and spirituous liquors aggravate all the complaints.

Now, in what manner are these singular affections to be explained ? We believe,
with our author, that they are in part owing to the diminished pressure of the atmo-
sphere, but infinitely more to a deficiency of oxygen.

It is clearly ascertained, that respiration supports animal life, and all its actions. This
process requires the presence of two principles. These are oxygen and combustible
matter. The former is supplied chiefly through the medium of the lungs, and the lat-
ter by the stomach. Of the vital actions, none seems to be more immediately depem
ent and strikingly regulated by respiration than the muscular. It is not, however, my
design to dwell on the relation between them. It is sufficient for my purpose to re-
mark, that during exercise a greater quantity of oxygen is extracted from the atmosphere
by the lungs, and that carbonic acid and water are formed, and caloric evolved in cor-
responding proportions. Hence it may be deduced, that during muscular exertion,
there is a greater demand for oxygen, and a larger consumption of combustible matter. It
also follows, that if the preceding premises be admitted, as a legitimate corollary, that
the same effect would be produced, namely, an exhaustion of the muscular vigour, by
withholding the one or the other of these agents. In either case, fatigue will be caused,
and the body rendered incapable of muscular exertion.— But the incapacity in the two
:s arises from different states of the svstem, and will be distinguished by different

cases ases

appearances, and removed by different methods of treatment.

Limited exercise in an atmosphere of sufficient density, slowly deprives the body oi
its proper quantity of combustible matter, until fatigue is finally induced. The body
is afterwards gradually recruit-rt by rest and food, or directly restored to momentary

169

ing$ such are the phenomena which attend the application of cupping
glasses.

The pressure of the air, on the surface of the globe is necessary to the
existence of bodies in the condition in which we see them. Several very
volatile fluids, as alcohol and ether, would become gaseous, under a less
pressure of ^ie atmosphere; water would boil, under eighty degrees

strength by the use of spirituous liquors, which are pure combustible matter mixed
with water.

Hut in the elevated regions of the atmosphere where there is a deficiency of oxygen,
the fatigue which comes on is of an opposite kind. It arises from an over-propwtion of
combustible matter, and a want of oxygen* ^Here, of course, it is alleviated by rest, and
deep inspirations, and exacerbated by exercise and spirituous liquors.

It is suddenly induced, because the pulmonary system is so contrived, that the body
at no instant receives more oxygen than what at the instant it requires. We are in-
structed by experiments, that animals placed in a vessel filled with oxygen, and respir-
ing the gas in a state of purity, do not consume more of it than when combined with
irrespirable gas. Thus, it takes an animal nearly four times as long-, to consume the
same quantity of oxygen as atmospheric air.

It is speedily removed, because, by the deep inspirations the necessary quantity of
oxygen is conveyed into the system.

It is accompanied by sickness of stomacJi, and loatldng of food, because, digestion, like
exercise, demands a copious supply of oxygen. There are many facts to prove, that
oxygen is a principal agent in digestion and assimilation. The quantity employed in
these processes seems, in some degree, to be regulated by the kind of food used. An
animal diet consumes more than a vegetable one. Mr. Spalding found that when he
lived upon animal food, and drank spirituous liquors, he expended the oxygenous por-
tion of the atmosphere in his diving bell, in a much shorter time than when he subsisted
on vegetable matter and water. Dr. Beddoes has also furnished some curious facts,
which go to establish the same conclusion.

It is attended by excessive tMrst, because, in a rare atmosphere, there will, of necessity,
be a profuse evaporation from the surface of the body.

The pulsations of the heart are more numerous, because they are performed less vigo-
rously.

Not altogether dissimilar in its nature, or origin, though milder in its symptoms, and
slower in its occurrence, is the fatigue occasioned bv immoderate exercise under the
ordinary constitution of the atmosphere. In this case, we observed an increased fre-
quency of the pulse, and of respiration, &c. &c. The cure, likewise, is by rest. Cold
•water is found more refreshing than spirituous liquors.

There is another phenomenon connected with the present subject, which deserves
to be noticed. 1 allude to the propensity to sleep which has already been remarked.
This, too, can only be explained by ascribing it to a deficiency of oxygen.

Sleep is a suspension of all or a majority of the operations of the mind. We have
not, it is true, in our possession any direct evidence to prove that the efiorts of the in-
tellect, like those of the body, exact a fixed and determinate quantity of oxygen. We
had, indeed, the promise of some experiments to ascertain it by Lavoisier, in an essay,
where, after indicating the expenditure of vital air by muscular exercise, he undertakes
to show by calculation, "the quantity of mechanical labour exerted by the philosopher
who refects, by the man of letters who writes, or the musician who composes.' These
operations, he adds, though intellectual, have a certain dependence on the physical
and material part of man, which renders them susceptible of comparison with the la-
bours of the mechanic.

Whether these views be just as they are brilliant, I shall not pretend to decide. But,
though we may never be competent to determine, with much accuracy, the quantity of
oxygen consumed by the operations of the mind, yet, that it is essentially necessary to
the exertion of the intellectual faculties is sufficiently probable.

With respect to the influence of a subtraction of oxygen in the production of sleep,
a few facts will be sufficient to attest it.

In the first place, we know that the primary operation of all the irrespirable gases,
and these contain no oxygen, is productive of heaviness and sleep.

Sleep is apt, moreover, to occur during the progress of digestion, when the oxygen
of the system is employed, in a considerable degree, in the assimilation of aliment, and

170

of temperature (Reaumur's scale;) solid bodies themselves might be-
come fluid. In a word, a considerable diminution in the weight of the
atmosphere would have absolutely the same effect, as raising its tempera-
ture to a very great height, which, changing the face of the universe,
would convert all liquids into elastic fluids, and would, doubtless, melt
all solid bodies.

The variations in the weight of the atmosphere, distinguishable by the
barometer, are of very little importance to the physiologist, and, I might
even add, to the physician, notwithstanding the minute attention with
which some writers note the state of the barometer, of the thermometer,
and hygrometer, and of the electrical state of the atmosphere, in giving
an account of a disease, or of an experiment, on which the above circum-
stances have no apparent or certain influence. The atmosphere, like
every other fluid, has a perpetual tendency to a state of equilibrium,
hence the rush of air into the lungs, or into other situations in which its
quantity is diminished, by the combinations which it forms, or by the ef-
fects of heat which renders it lighter, by rarefaction : the same principle
explains the formation of the trade and other winds.

The atmospherical air combines with water and dissolves it, as the lat-
ter dissolves saline substances. In this consists the process of evapora-
tion. The air becomes saturated with water, in the same manner as wa-
ter becomes saturated with salt, to such a degree, as to be incapable of
holding a greater quantity in solution. As its temperature rises, its sol-
vent power increases, and the latter diminishes, as it grows cold ; varia-
tions of temperature produce the same effect on solutions of salts in li-
quids. The formation of all the aqueous meteors, depends on the differ-
ent conditions of the solvent powers of the atmosphere; when c msicler-
able, the atmosphere is warm and dry, and the air serene; clouds form,
when it is saturated; dews, fogs, and rain, are the consequence of a di-
minution of its solvent power, as snow and hail, of a degree of cold which
precipitates the fluid. The different degrees of dryness or moisture,
marked by the hygrometer, only sensibly affect the human body, when it
has been exposed for a considerable time to its influence.

Chemically considered, the atmospherical air, which was long regard-
ed as a simple body, is composed of about 0,27 of oxygen, 0,73 of azote,
and of 0,01 or 0,02 of carbonic acid. The proportions of oxygen, ac-
cording to Humboldt, vary from 0,23 to 0,29; that of azote, is almost al-
ways the same; carbonic acid is the more abundant, as the air is less
pure*. This part of natural philosophy, which is called eudiometry, or

the elaboration of chyle ; or, if the disposition to sleep be counteracted, the senses, at
least, become more dull, and the understanding less acute and energetic.

The production of sleep, is favoured, too, as has been proved, by external warmth,
which lessens the supply of oxygen.

It is from the combination of these causes, that among the inhabitants of hot climates,
the custom of sleeping during the day, and especially after eating1, unviersally prevails.
We must acknowledge that the outline of this theory was derived from the Lectures of
Mr. Allen, of Edinburgh, on Physiology.- — Chapman.

* Th s is pretty nearly the original estimate of Lavoisier, whose experiments have
since been very frequently repeated, and with no material difference in the results. It
is, however, proper to recollect, in speaking of the relative proportion of the ingredi-
ents of the atmosphere, that this estimate must be considered as having reference to
•weight and not to measure. On this point Lavoisier is silent, as well as most other che-
mical writers. It is nevertheless a fact, as has been more particularly shxnvn by Ber-

171

the measurement of the purity of the air, is far from accomplishing what
its name indicates, and has disappointed the hopes which had been en-
tertained on the subject. Eudiometrical instruments can inform us, on-
ly of the proportion of oxygen contained in the atmosphere; now, its sa-
lubrity, its fitness for respiration, is not in proportion to the quantity of
oxygen. The volatilized remains of putrid animal or vegetable substan-
ces, various mephitic gases, combine with it, and affect its purity. In
the comparative analysis of air procured on the Alps and in the mar-
shes of Lombardy, there was found in each the same quantity of oxygen;
and yet, those who breathe the former, enjoy robust health, while the
inhabitants of the marshy plains of Lombardy are carried off by epidemic
diseases, are pale, emaciated, and habitually lead a languid existence.

Though, at least, 0,20 of oxygen are necessary to render the air fit for
respiration, the proportion may be diminished to seven or eight parts in
the hundred ; but in such cases, the breathing is laborious, panting, and
attended with a sense of suffocation, in short, asphyxia comes on, even
while the air stil! contains a certain quantity of oxygen, of which the lungs
cannot entirely deprive it. Whenever a number of persons are collected
in a confined place, in which the air cannot be easily renewed, the quan-
tity of oxygen diminishes rapidly, that of carbonic acid increases. The
latter, in consequence of hs specific gravity, sinks to the lowest part, and
strikes with death every living being which it envelopes. When two
lighted candles, of different lengths, are placed under the same bell, the
shorter candle goes out first, because the carbonic acid formed during
combustion, sinks to the most depending part. For the same reason, the
pit is the most unhealthy part of a play-house, when a great number of
people after remaining in it for several hours, have deprived the air of a
cousiderable portion of its oxygen.

Persons collected together, and enclosed in a small space, injure each
other, not only by depriving the atmosphere of its respirable element, but
particularly by altering its composition, by the combination of all the sub-
stances exhaled from their bodies. These volatilized animal emanations,
become putrid, while in the atmosphere, and conveyed to the lungs dur-
ring respiration, becomes the germ of the most fatal diseases. It is in this
manner, that the jail and hospital fevers so fatal to almost all whom it at-
tacks, arises and spreads. A dry and temperate air containing 0.27 of
oxygen and 0.73 of azote, and free of other gases, or other volatilized
substances, is the fittest for respiration. In certain cases of disease, how-
ever, this function is most freely performed in a less pure air. Thus,
patients labouring under pulmonary consumption, prefer the thick and
damp air of low situations, to the sharp and dry air of mountains; nerv-
ous women prefer that in which horn, feathers, or other animal substances
are burning. An atmosphere highly electrical, at the approach of a storm,
renders respiration very laborious, in some cases of asthma. In short,

thollet, that the atmosphere contains only twenty-two parts of oxygen, in the hundred,
by measure.

By some chemists it has been supposed, from the circumstance of the carbonic acid
being generally found in a larger quantity near the earth, that it is an accidental, and
not an essential constituent of the atmosphere. But by De Saussure it was detected in
the air, on the summit of Mont Blanc ; and from this, and a variety of other considera-
tions, it would appear to be a uniform part of atmospheric air, existing most probably
in a state of chemical combination. — Chapman.

172

the qualities of the air must be suited to the condition of the vita!
power in the lungs, as those of the food, to the sensibility of the stomach.

Being obliged, on this subject, to content myself with the ungracious
office of compiler, I hasten to bring this article to a close, and to refer the
reader for a fuller account of the air, considered in its physical and
chemical relations, to the works of M. M. Fourcroy, Hauy, Brisson, Sec.
to that of M. Guyton Morveau, on the method of purifying the air, when
from different combinations, it becomes unfit for respiration.

LXXI. In man and in all warm-blooded animals, with a heart contain-
ing two auricles and two ventricles, the blood which has been conveyed
to all the organs by the arteries, and which has been brought back, by the
veins, to the heart, cannot return to it, without having previously passed
through the lungs, which are viscera destined to the transmission of air;
of a spongy texture, and through which the blood must, of necessity cir-
culate to get from the right to the left cavities of the heart. This course of
the blood constitutes the pulmonary or lesser circulation: it does not exist
in some cold-blooded animals. In reptiles, for instance, the heart has
but one auricle and one ventricle ; the pulmonary artery in them, arises
from the aorta, and conveys but a small proportion of the blood ; hence
the habitual temperature of these animals is much lower than that of
man. For the same reason too, there exist so small a difference, be-
tween their venous and arterial blood; the quantity of fluid vivified by
exposure to the air, in the pulmonary tissue, being too small to effect, by
its union with the general mass, a material change on its qualities.

Mayow has given the most accurate notion of the respiratory organ,
by comparing it to a pair of bellows, containing an empty bladder, the
neck of which by being adapted to that of the bellows, should admit air
on drawing asunder its sides. The air, in fact, enters the lungs, only
when the chest dilates and enlarges, by the separation of its parietes,
agents of respiration are, therefore, the muscles which move the parietes
of the chest, these are formed of osseous and soft parts, in such a man-
ner, as to possess a solidity proportioned to the importance of the organs
which the chest contains, besides a capacity of motion required to carry
on the functions intrusted to them.*

To carry on respiration which may be defined the alternate ingress of
air into the lungs, and its egress from those organs, it is necessary that
the dimensions of the chest should be enlarged (this active dilatation of
the cavity of the chest is called inspiration,) and that it should contract to
expel the air which it had received during the first process. This se-
cond action is called expiration, it is always of shorter duration than the
former, its agents are more mechanical, and the muscles have much less
influence upon it.

The parietes of the chest are formed, at the back part, by the verte-
bral column, at the fore part by the sternum, and on the sides by the
ribs, which are osseo cartilaginous arches, situated oblique between
the vertebral column, which is fixed and becomes the point of support of
their motions, and the sternum which is somewhat moveable — the spaces
between the ribs are filled by muscular planes of inconsiderable thick-
ness, the internal and external intercostal muscles, the fibres of which

* See APPENDIX, Note U, for remarks on the mechanism of the respiratory
organs.

173

lie in opposite directions. — Besides, several muscles cover the outer part
of the thorax, and pass from the ribs to the neighbouring bones ; as the
subclavian muscles, the great and lesser pectorals, the serrati, the lastissi-
mi dorsi, the scaleni, the longissimi dorsi, the sacro lumbales, and the
serrati minores, posterior, superior, and inferior. But of all the mus-
cles which form the anterior, posterior, and lateral parietes of the chest,
the most important is the diaphragm, a fleshy and tendinous partition, ly-
ing horizontally between the chest and the abdomen, which it separates
from each other ; it is attached to the cartilages of the false ribs, and to
the lumbar vertebrae, and has three openings to transmit the oesophagus
and the vessels which pass from the abdomen to the chest, or from the
latter into the abdomen.

In health the chest dilates only by the descent of the diaphragm. The
curved fibres of that muscle straightened in contraction, descend towards
the abdomen, and compress the viscera. The descent of the viscera
thrusts forward the interior parietes of that cavity, and these recede,
when on expiration taking place after inspiration, the diaphragm now re-
laxed, rises, pressed upwards by the abdominal viscera, compressed them-
selves by the large muscles of the abdomen. But when it is necessary to
take into the chest a great quantity of air, it is not sufficient that it should
be enlarged merely by the descent of the diaphragm — it is required be-
sides, that its dimensions should be increased in every direction. The inter-
costal muscles then contract, and tend to bring together the ribs between
which they are situated. The intercostal spaces, however become wider,
especially at their anterior part, for, whenever lines falling pbliquelyona
vertical line, change their direction, approaching to a right angle, the in-
termediate spaces receive the greater increase, as the lines, more oblique
at first, become at last more nearly horizontal. Besides, as the ribs are
curved in the course of their length, in two directions, and both the di-
rection of their faces, and edgewise, the convexity of the first curvature is
outwards, the ribs recede to a distance from the axis of the chest, whose
cavity is enlarged transversely, while the second curvature (in the direc-
tion of their edge) being increased by a real twisting of these bones, and
which reaches to the cartilaginous parts, the sternum is heaved forward
and upward, so that the posterior extremity of the ribs is removed from
their sternal end. But as the ribs are not all equally moveable, as the
first is almost always invariably fixed, and as the others are moveable in
proportion to their length, the sternum is tilted in such a way that the
lowermost extremity is thrust forward*. The diameter of the chest from
the fore to the back part increases, therefore, as well as the transverse
diameter. This increase of dimensions has been estimated at two
inches, to each of these diameters; the dimensions of the vertical dia-
meter, which are regulated by the depression of the diaphragm, are much
greater.

LXXII. Professor Sabatier, in his memoir on the motion of the ribs,
and on the action of the intercostal muscles, maintains that during the

* The opinion originally advanced by Haller, of the immobility of the first rib, has
been very properly contested by Magendie, (Precis. Elem.) In certain states of dis-
ease where FORCED inspirations are frequently made, we can readily satisfy ourselves
that the upper part of the chest is very freely dilated by the action of the scaleni ser-
rati, &c. In asthma we have repeatedly had occasion to remark this mobility. —
Godman.

174

action of inspiration, the upper ribs alone rise, that the lower ribs descend
and slightly close on the chest, while the middle ribs project outwardly,
and that in expiration, the former set of ribs descend, that the latter start
a little outwardly, and that the middle set encroach on the cavity of the
chest. The learned Professor adds, that the cartilaginous articulating
surfaces, by which the ribs are connected to the transverse processes of
the vertebrae, appear to him to favour these different motions, as the di-
rection of the articulations of the upper ribs, is upward, and that of the low-
er downward; but on considering the subject with attention, it will be
seen, that the surfaces by which the transverse processes of the verte-
brae are articulated to the tuberosities of the ribs, are turned directly for-
ward in the greatest number, some of the lower ribs are, at the same
time, directed slightly upward. If we examine the action of the bones
of the chest, during inspiration, in a very thin person, for example, in
phthisical patients, whose bones are covered with little else than skin, we
shall find, that all the ribs rise, and are carried somewhat outwardly. It
is not easy to conceive how the intercostal muscles, which Professor Sa-
batier considers as the agents of respiration, should elevate the upper
ribs and depress the lower. The diaphragm, whose circumference is in-
serted in the latter, might, by its contraction, produce this effect; but as
the intercostals have their fixed point of action in the upper ribs, they
oppose and neutralize this effort, and all the ribs are elevated at once.
If this were not the case, the ribs ought to be depressed, whenever the
intercostals contract, since the lowermost, fixed by the diaphragm, would
become the §x«d point on which all others should move.

As the fibres of the external and internal intercostal muscles, are in di-
rect opposition to each other, those of the former set of muscles having
an oblique direction, from above downward, and from behind forward,
and crossing the fibres of the other set whose obliquity is in a different di-
rection ; several physiologists have thought, that these muscles were op-
posed to each other, that the internal intercostal muscles brought toge-
ther the ribs, after they had been separated by the external intercostals,
the one set being muscles of expiration, while the other set contracted
during inspiration.

It is well known with what pertinacity, Hamberger, in other respects,
a physiologist of considerable merit, defended this erroneous opinion, in
his dispute with Haller; it is now, however, ascertained, that all the in-
tercostal muscles concur in dilating the chest, and that they ought to be
ranked among the agents of inspiration, because the unequal capacity of
motion in the ribs, prevents the internal intercostals, the lower insertion
of which is nearer to the articulation of these bones to the vertebrae, from
depressing the upper ribs. Of the very conclusive experiments,by which
Haller undertook to refute the arguments of his adversary, I shall relate
only that which is performed by stripping the parietes of the chest, in a
living animal, of all the muscles which cover it, and by removing, in dif-
ferent pails of the thorax, some of the external intercostal muscles. The
internal intercostals are then seen to contract during inspiration, toge-
ther with the remaining external intercostals. These muscles, therefore,
have a common action, and are not in opposition to each other. The
same experiment serves to prove the increased dimensions of the space
between the ribs. On holding one's finger between two of the ribs, it
feels less confined, when during inspiration, these bones rise and thrust
forward the sternum.

175

This question being at rest, although in pursuit of science one should
inquire how things are effected, and not, wherefore they come to pass, one
feels naturally desirous to know what purpose is answered by the different
direction of the fibres of the two sets of intercostal muscles; and with
what view Nature has departed from her wonted simplicity, in giving to
their fibres opposite directions. In answer to this, one may observe, that
the action of powers applied obliquely to a lever, being decomposed in
consequence of that obliquity, a part of the action of the external inter-
costals would tend to draw the ribs towards the vertebral column, which
could not happen, without forcing back the sternum, if the internal inter-
costals did not tend to bring forward the ribs, at the same time that they
elevate them; so that these two muscular planes, united in their action
of raising the ribs, antagonise and reciprocally neutralize each other, in
the effort by which they tend to draw them in different directions.

To this advantage of mutually correcting the effects that would result
from their respective obliquity, may be added the benefit arising from a
texture capable of a greater resistance ; it is clearly obvious, that a tissue
whose threads cross each other, is firmer than one in which ail the
threads merely in juxta position, or united by means of another substance,
should all lie in the same direction. Hence, Nature has adopted this
arrangement, in the formation of the muscular planes constituting the
anterior and lateral parietes of the abdomen, without which the abdomi-
nal viscera would frequently have formed herinary tumours, by sepa-
rating the fibres and getting engaged between them. In this respect, one
may compare the tissue of the abdominal parietes, in which the fibres of
the external and internal oblique muscles, which cross each other, are
themselves crossed by the fibres of the transversales, to the tissue of those
stuffs whose threads cross each other, or rather to wicker work, to which
basket-makers give so much strength, by interweaving the osier in a va-
riety of directions.

LXXIII. When from any cause, respiration becomes difficult, and the
diaphragm is prevented from descending towards the abdomen, or the
motion of inspiration is impeded, in any way, the intercostals are not alone
employed in dilating the chest, but are assisted by several other auxiliary
muscles; the scaleni, thesubclavii, the pectorales, the serrati inagni, and
the latissimi dorsi, by contracting, elevate the ribs, and increase, in more
directions than one, the diameter of the chest. The fixed point of these
muscles, then, becomes their moveable point, the cervical column, the
clavicle, the scapula, and the humerus, being kept fixed by other powers,
which it is unnecessary to enumerate. Whoever witnesses a fit of con-
vulsive asthma, or of a suffocating cough, will readily understand the im-
portance and action of these auxiliary muscles.

Inspiration is truly a state of action, an effort of contractile organs,
which must cease when these are relaxed. The expiration which follows
is passive, and assisted by very few muscles, and depends chiefly on the
re-action of the elastic parts entering into the structure of the parietes
of the chest. We have seen, that the cartilages of the ribs are pretty
considerably twisted, so as to carry outward and downward their upper
edge : when the cause which occasions this twisting ceases to act, these
parts return to their natural condition, and bring back the sternum to-
wards the vertebral column, towards which the ribs descend, from their
weight. The diaphragm is forced towards the chest, by the abdominal
viscera, which are compressed by the broad muscles of the abdomen.

176

i

In every effort of expiration, as in cough and vomiting, these muscles
re-act, not merely by their own elasticity, but they besides contract and
tend to approach towards the vertebral column, by pressing upwards the
abdominal viscera towards the chest. The triangularis sterni, the sub-
costales, and the serratus inferior pasticus, may likewise be ranked among
the agents of expiration; but they appear to be seldom employed, and to
be too slender and weak to contribute much to the contraction of the
chest.

LXXIV. When the chest enlarges, the lungs dilate and follow its pa-
rietes, as these recede from each other. These two viscera, soft, spon-
gy, and of less specific gravity than water, covered by the pleura which
is reflected over them, are always in contact with the portion of that
membrane which lines the cavity of the thorax; no air is interposed be-
tween their surfaces (which are habitually moistened by a serous fluid
exuding from the pleura) and that membrane, as may be seen, by open-
ing, under water, the body of a living animal, when no air will be seen to
escape. As the lungs dilate, their vessels expand, and the blood circu-
lates through them more freely; the air contained in the innumerable
cells of their tissue, becomes rarefied, in proportion as the space in which
it is contained is enlarged. Besides, the warmth communicated to it by
the surrounding parts, enables it, in a very imperfect manner, to resist
the pressure of the atmosphere, rushing through the nostrils and mouth
into the lungs, by the opening in the larynx which is always pervious, ex-
cept during deglutition.

LXXV. The pulmonary tissue into which the air is thus drawn in,
every time the capacity of the chest is increased, does not consist mere-
ly of air-vessels, which are but branches, of different sizes, of the two
principal divisions of the trachea, but is formed, likewise, by the lobular
tissue into which these canals deposit the air; it contains also a great
quantity of lymphatics and blood-vessels, of glands and nerves. Cellu-
lar tissue unites together all these parts, and forms them into two masses
covered over by the pleura, and of nearly the same bulk*; suspended in
the chest from the bronchia and trachea, and every where in contact
"with the parietes of the cavities of the chest, except towards their root,
at which they receive all their nerves and vessels.

The pulmonary artery arises from the base of the right ventricle, and
divides into two arteries, one to each lung. On reaching the substance
of these viscera, these vessels divide into as many branches as there are
principal lobes. From these branches, there arise others, which again
subdivide into lesser ones, until they become capillary, and continuous
with the radicles of the pulmonary veins.

These vessels, formed from the extremities of the artery, unite into
trunks, which progressively enlarging, emerge from the lungs, and open,
four in number, inio the left auricle. Besides these large vessels, by
means of which, the cavities in both sides of the heart communicate to-
gether, the lungs receive from the aorta two or three arteries, called bron-
chial arteries, these penetrate into their tissue, and follow the direction
of the other vessels, and terminate in the bronchial veins, which open in
the superior cava, not far from its termination into the right auricle.-—
These bronchial vessels are sufficient for the nourishment of the pulmo-

* It is well known that the right lung is larger than the left, that it is divided into
three principal lobes, while the latter has only two. — Jiuthm's J\"ote.

177

mry organ, which, in reality, is not near so bulky as it appears, as may
be ascertained by examining the lungs, after all the air has been extract-
ed from them, by means of an air pump, applied to the trachea.

Physiologists, for the most part, consider the bronchial arteries as the
nutritious vessels of the lungs. They assert, that as the blood which flows
along the branches of the pulmonary artery resembles venous blood, it
is unfit for the nutrition of the lungs, and that it was necessary that these
organs should be supplied by arteries arising from the aorta, and contain-
ing- blood analogous to that which is sent to every part of the body. But
though it be admitted, that this venous blood, brought from every part of
the body, and sent into the lungs, by their principal artery, may not be
tit to maintain the organ in its natural economy, this blood is' fit for that
use, when, after being made hot, spumous, and florid, by the absorption
of the atmospherical oxygen, it returns by the pulmonary veins, into the
left cavities of the heart*.

Some have thought, that the blood which flows in the bronchial vessels,
exposed to the action of the air, ''like the portion of this fluid which tra-
verses the pulmonary system, Idst nothing of its arterial qualities, and
that, poured by the bronchial veins into the superior or descending vena
cava, it was a necessary stimulus for the right cavities of the heart, of
which blood entirely dark and venous, would not have awakened the con-
tractility. But even, if the experiments of Goodwin had not proved,
that the parietes of these cavities have a sensibility relative to dark blood,
by virtue of which, this stimulus is sufficient to determine their contrac-
tion, the action of the heart does not depend as closely as has been said,
on the impression of the blood on its substance, since it contracts, though
empty, and prolongs its contractions to relieve itself of the black blood
which fills it, when an animal dies of asphyxia.

Boerhaave, who admitted one sort of peripneumony depending on the
obstruction of the bronchial vessels, whilst another, according to the same
writer, depends on the obstruction of the pulmonary vessels, seems to
justify, in some measure, the reproach, exaggerated unquestionably,
which some authors have thrown out against anatomy, of having rather
retarded than accelerated the progress of the Hippocratic practice of
medicine. The anatomical analysis of the lungs, or the distinction of the
tissues which enter into their composition, furnishes juster ideas on the
difference of the inflammations by which they may be attacked. It has

* That the bronchial vessels exclusively nourish the lungs, is an opinion entertained
certainly by a majority of physiologists. When, however, we compare the size of these
vessels with the magnitude of the office assigned to them, it seems very doubtful whe-
ther they are adequate to it. We are inclined to believe notwithstanding what is al-
leged ag-ainst it, that the pulmonary arteries also contribute to the nourishment of the
lungs; and indeed there is a fact which almost proves it. We allude to the circum-
stance of the pulmonary adhesions, which are supposed to take place in consequence
of inflammation, having been repeatedly injected from the trunk of the pulmonary ar-
teries.— Chapman.

The circumstance mentioned at the conclusion of the preceding note, by no means
settles the dispute. We can throw coloured water or mercury into the trachea, and it
will flow into the pulmonary arteries, pulmonary veins, and bronchial arteries. Should
the material be thrown into the pulmonary artery, it will enter the pulmonary veins,
the bronchise and trachea. If it is thrown into the pulmonary vein, it penetrates the
bronchiis, and pulmonary arteries. Considering- the character of the membrane which
forms the texture of these organs, we cannot see any difficulty in believing- the bron.
chial arteries sufficiently larg-e to nourish the lungs. — Godman.

z

178 r%jT

been seen, that of these pulmonary phlegmasise, the commonest and least
serious catarrh consists in inflammation of the mucous membrane which
lines the air passages, whilst the real peripneumony has its seat in the
parenchyma of the organ, which it converts into a hard and compact
mass. It is this state that anatomists have long designed under the nam.c
of hepatization, because, in fact, the substance of the lung has acquired
the hardness, the weight, and something of the appearance of the liver.
The same anatomical researches have shown that pleurisy consists in
inflammation of the pleura, and of the surface of the lung, an inflamma-
tion which sometimes leaves no trace, but which oftener exhibits, on the
opening of bodies, the pleura thickened and opaque, covered with a layer
of coagulabie lymph, whitish, more or less thick, or even adhering to
the lung*.

There arise from the surface, and from the internal substance of the
lungs, a prodigious number of absorbents, which may be divided into
superficial and deep seated. The latter accompany the bronchial tubes,
and penetrate into the substance of th& glandular bodies situated where
those air-vessels divide, but collected, in greatest number, towards the
root of the lungs and at the angle formed by the bifurcation of the tra-
chea. These bronchial glands, belonging to the lymphatic system, do
not differ from the glands of the same kind, and are remarkably only by
their number, the size, and their habitually darkish colour. The absorb-
ents of the lungs, after ramifying in these glands, terminate in the upper
part of the thoracic duct, at the distance of a few inches from its termi-
nation into the subclavian vein. Lastly, the lungs, though endowed with
a very imperfect degree of sensibility, have a considerable number of
nerves furnished by the great sympathetic, and especially by the eighth
pair.

It was long believed, on the authority of Willis that the aerial tissue
of the lungs is vesicular, that each ramification of the bronchise termi-
nated in their substance, in the form of a small ampullula; but at pre-
sent, most anatomists adopt the opinion of Helvetius. According to
Helvetius, every air-vessel terminates in a small lobe, or kind of sponge
fitted for the reception of air, and formed of number of cells communi-
cating together.— These lobes, united by cellular tissue, form larger
lobe-s, and these together form the mass of the lungs.

The tissue that connects together the different lobes is very different

* These adhesions of the lung to the pleura costalis, are so, common, that the old
anatomists considered them as a natural disposition, and called them ligaments of the
Jungs. It has been believed till now, that these adhesions arose from the organization
of a substance transuding from the two surfaces. Numerous dissections have con-
vinced me, that in all the points where they are met with, the pleura has disappeared,
that it is decomposed, and that, whether it he at the surface of the lungs, or within
the ribs and the muscles, it is produced by the act of inflammation, that it is become
cellular, by the thinning of its tissue and the separation of its lamina. The pleura
thus reduced to cellular tissue, the adhesion is produced by the first intention, in the
same way as in simple wounds immediately united. There is no organ that abounds
more than the lungs in facts important to morbid anatomy. The variety of appearances
they exhibit, on the opening of bodies, are almost innumerable; and to give one in-
stance, the pleura appears after pleurisy in five perfectly distinct conditions. 1st. In its
natural state, when the disease being incipient and slight, the resolution is effected at
the moment of death.— 2dly. When it is red, thickened, and opake. — 3dly. When it
is covered with coagulabie "lymph.— 4th ly. When it adheres. — Sthly. When, in conse-
quence of chronic inflammation, hydrothorax has taken place, &c. &c. — Author's Note.

179

from that in which the ramifications of the bronchiae terminate; air never
penetrates in it, except when the tissue of the air cells is ruptured. On
such occasions, which are not of rare occurrence, on account of the ex-
cessive thinness of the lamina of the air cells of that tissue, the lung
loses its form, and becomes emphysematous. Haller estimates at about
the thousandth part of an inch, the thickness of the parietes of the air
cells, and as the extreme ramifications of the plilmonary vessels are dis-
tributed on these parieres, the blood is almost in immediate contact with
the air. There can be no doubt, that the oxygen of the atmosphere acts
on the blood, under such circumstances, since it alters its qualities, and
communicates to it a florid red colour, when enclosed in a pig's bladder,
and placed under a vesr.el filled with oxygen gas.

LXXVI. Every time the chest dilates, in an adult, there enter into
the lungs, between thirty and forty cubic inches of atmospherical air*,
consisting, when pure, of seventy-three parts of azote, twenty-seven of
oxygen, und one or two parts in the hundred, of carbonic acidf.

When the air has been exposed, for a few moments, in the pulmonary
tissue, it is expelled by the effort of expiration, but it is diminished in
quantity, and is reduced to thirty-eight inches. Its composition is no
longer the same: it contains, it is true, 0,79 of azote; but the vital portion
fit for respiration, the oxygen, has undergone a great diminution, its
proportion is only 0,14: carbonic acid forms the remaining seven hun-
dreths, and there are sometimes found one or two pars of hydrogen. It
is besides affected by the addition of an aqueous vapour, which is condensed
in cold weather, as it escapes at the mouth and nostrils. It is called the
humour of the pulmonary transpiration. These changes, compared to
those which the blood experiences in passing though the lungs, clearly
show a reciprocal action of this fluid and of the oxygen of the atmosphere.
The dark venous blood which coagulates slowly, and which then disen-
gages a considerable quantity of serum abounding in hydrogen and carbon
and of a temperature of only thirty degrees, yields its hydrogen and car-
bon to the oxygen of the atmosphere, to form carbonic acid and the pul-
monary vapour; and as oxygen cannot enter into these new combinations,
without parting with a portion of caloric which keeps, it in a state of
gas, the blood acquires this warmth, which is disengaged the more rea-
dily, according to the ingenious experiments of Crawford, as by parting
with its hydrogen and carbon, its capacity for caloric increases in the pro-
portion of 10 : 1 1.5.

* Some physiologists think that the quantity of air inspired is much less considera-
ble. Professor Gregory, of Edinburgh, states, in his public lectures, that scarcely
two inches of air enter into the lungs, at each inspiration. It may be proved, how-
ever, that this calculation is inaccurate ; either by drawing- a full inspiration, as was
done by Mayosv, at the expense of a cei-tain quantity of air contained in a bladder, or
by breathing1 into a vessel connected with a pneumatic apparatus the air taken in, by
drawing- a deep inspiration. Or else one may inflate the lungs of a dead body by
adapting to the trachea, a stop-cock connected with a curved tube to receive the air
under a vessel of the same apparatus. Various means have been employed to mea-
sure the capacity of the chest. Boerhaave placed a man in a tub containing water
above his shoulders, he then made him take a deep inspiration, and measured the
height at which the fluid rose from the dilatation of the chest. Keill injected water
into the chest of a dead body. Lastly, it has been proposed to inject the bronchial
tubes and the lobular tissue into which they terminate, with fusible metal consisting of
eight parts of pewter, five of lead, three 'of bismuth, to which may be added one of
mercury. — Author's Note.

t See APPENDIX, Note W, for observations on the changes induced on the air,
and on the blood, by respiration,

180

In parting with its carbon which, by uniting with oxygen, forms the
carbonic arid that is thrown out during expiration, the blood loses its
dark and nearly purple colour, and becomes of a florid red, and its con-
sistence increases, from the escape of its hydrogen and of its aqueous
parts. Besides, as it absorbs a certain quantity of oxygen, it becomes
spumous and light : its concrescibility and plasticity increase, and on
coagulating, there is separated from it, a smaller quantity of serum.

After parting with its hydrogen and carbon, ^hd combining with oxy-
gen and caloric, in its passage through the lungs, the blood, which has be-
come arterial, parts with these two principles, in proportion as in reced-
ing from the heart, it forms new combinations, and is converted into oxy-
des of hydrogen and carbon, which on receiving an additionl quantity of
oxygen, are changed into water and carbonic acid, when on being carried
along with the venous blood, into the pulmonary tissue, they are exposed
to the influence of the atmospherical air.

The arterial blood becomes venous, by yielding its oxygen, when any
cause whatever suspends or slackens its course, as is proved by the fol-
lowing experiment of John Hunter. He tied the carotid artery of a dog,
with ligatures placed at the distance of about four inches from each other:
the blood contained in the portion of artery included between the two li-
gatures, on laying open this part of the vessel, at the end of a few hours,
was found coagulated and as dark as that in the veins. The blood con-
tained in an anetorismal sac, and which is frequently found in a fluid state,
when the internal coats of the artery are but lately ruptured, becomes
venous after remaining in it some time. The changes, however, which
the blood undergoes in its course through the arterial system, are not
very remarkable, owing to the rapidity with which it flows along those
vessels; there is less difference between the blood contained in an artery
near the heart, and that contained in an artery at a distance from that or-
gan, than in the blood taken from the veins near their extremities, and
from the great trunks which deposit it into the right auricle. The blood
in the small veins resembles arterial blood, and frequently in a very co-
pious bleeding, the colour of the blood, which, at first, is very dark,
gradually becomes less dark, till towards the end of the bleeding, it shows
nearly the same qualities as if arterial ; a phenomenon which, as is well
observed by the English writer already quoted, depends on the more easy
and rapid flow of the blood'of the arteries into the veins, in consequence
of the evacuation of the venous system. This observation is a complete
icfutation of the assertion of Bellini, who maintains, that when a vein is
wounded, the blood which comes from it, forms a double current which
flows out at the wound. The above opinion is maintained by highly dis-
tinguished phosiologists, as Haller and Spallanzani, who support it by

* Sir Humphrey Davy gives the following results of experiments made on his own
respiration :

After one strong expiration, his lungs contained 330 cubic inches ; after a natural
expiration, 970 cubic inches; after a natural inspiration, 11Q6 cubic inches; after a
strong inspiration, 3206. By a strong expira^on, after a deep inspiration, 1556 cubic
inches were thrown out of the lungs. After a natural inspiration, 643 cubic inches,
and after a natural expiration, 353. Mr. Thompson supposes that the quantity of air
usually contained in the lungs is 2294 cubic inches, and that 327 cubic inches enter or
escape in inspiration or expiration. If we allow 20 inspirations a minute, we should
have entering and escaping from the lungs in this time 6500 cubic inches, and in
twenty-four hours, 75,556 cubic inches, or 48 pounds. — Godman,

experiments performed on the vessels of cold-blooded animals, or on
veins without valves. In bleeding at the bend of the arm, the blood can-
not come from that part of the vessel which is above the wounds: the
valves oppose insuperable obstacles to its retrograde flow; hence it is
very easy to distinguish the red blood which comes from the lower extre-
mity of the vein, from that which flows from the upper end, and which
is poured into the vessel by the veins which open into it, between the
puncture and the nearest valve.

In its course to the parts among which the arteries are distributed,
the blood, vivified in 'its passage through the lungs, and fitted, as Four-
croy says, for a new life, loses its oxygen and caloric. Its capacity for
the latter, diminishes, in proportion as the oxygen, by combining with
hydrogen and carbon, restores it to the venous state.

This theory of the process by which the blood parts with its oxygen?
in its progress along the blood-vessels, is rendered still more probable,
by recent discoveries on the nature of the diamond. This substance is
the only pure carbon, and that which is calle^ so by chemists, is an oxyde
of carbon which owes its dark colour to the oxygen with which it is
combined. Before these experiments, it was not easy to determine the
particular condition of the carbon which exists so plentifully in venous
blood.

No precise calculation has yet been made, of the quantity of the oxy-
gen absorbed by the venous blood, nor of the quantity employed in the
combustion of hydrogen and carbon in the lungs, so as to form water and
carbonic acid*.

Is the carbon, in venous blood, merely combined with oxygen, or is it
united with hydrogen, so as to form carburetted hydrogen ? It appears to
me more probable, that the oxygen which is absorbed by combining with
hydrogen, in every part of the body, produces the water which dilutes
the venous blood, renders it more fluid, and richer in serum than arterial
blood; while, by its union with carbon, it forms an oxide that gives to the
blood the dark colour, which is one of its most remarkable characters.
On reaching the lungs., which are real secretory organs, the water is ex-
haled, dissolved in the air, and forms the pulmonary transpiration; the
oxide of carbon, completely decomposed by an additional quantity of
oxygen, constitutes carbonic acid, which gives to the air that is expired,
power of forming a precipitate in lime water.

The absorption of oxygen by the venous blood, explains how the phe-
nomena of respiration are continued into every part of the body, and
produce the warmth uniformly diffused over all our organs. In propor-
tion as the blood parts with its caloric, for which its affinity diminishes
as it becomes venous, the parts which give out their hydrogen and car-
bon, combine with it. If the lungs were the only organs in whieh caloric
might be disengaged, the temperature of those viscera ought considera-
bly to exceed that of other parts: experience, however, shows that the
temperature of the lungs is not sensibly more elevated.

This theory of respiration, for which we are entirely indebted to mo-
dern chemistry, is contradicted by no one phenomenon. The greater the

* Instead of saying that the venous blood absorbs oxygen, it will approach nearer the
state of our knowledge to believe that the venous blood gives off its carbon, which
combines, in the lung-s, with the oxygen of the inspired air. For a full view of the
latest opinions on this subject, see APPENDIX, Note W.

182

extent and capacity of the lungs, the more frequent is respiration, and
the greater the warmth and vivacity of animals. Birds, whose lungs ex-
tend into the abdomen by various membranous sacs, and whose bones are
hollow, and communicate with the lungs, consume a great deal of oxy-
gen, either on account of the magnitude of this respiratory apparatus,
or from their frequent, and, at times, hurried respiration. On that ac-
count, the habitual temperature of their body, exceeds that of man and
mammiferous animals. In reptiles, on the contrary, whose vesicular
lungs admit but a very small quantity of blood, and present to the atmo-
sphere a surface of very limited extent, and in which respiration is per-
formed with intervals of longer duration, the body is at a temperature
which, naturally, never rises above seven or eight degrees.

LXXVII. Though the temperature or warmth of the body is generally
proportioned to the extent of respiration, to the quantity of blood exposed,
in a given time, to the action of the atmospherical air, it may be higher
or lower, according to the degree of the vital energy of the lungs.
These organs should not \yp considered as mere chemical receivers :
they act on the air, digest it, as the ancients said, anil combine it with the
blood, by a power which is peculiar to them*. If it were otherwise,
there would be nothing to prevent a dead body from being restored to
life, by inflating with oxygen its pulmonary tissue. The ancients alluded
to this action of the lungs on the air we breathe, by calling that air the
pabulum vitx. Its digestion was, they thought, effected in the lungs, in
the same manner as the digestion in the stomach, of other aliments less
essential to life, and whose privation may be borne for a certain time,
while life is endangered, when the aeriform nutriment ceases to be fur-
nished to the lungs, for the short space of a few minutes.

In proof of the vitality of the lungs, and of the share which they have
in producing the changes which the blood undergoes in passing through
them, I may mention the experiment which proves that an animal placed
under a vessel filled with oxygen, and breathing that gas in a pure state,
consumes no more of it, than if it was received into the chest, mixed with
other gases unfit for respiration. A guinea pigi placed under a vessel
full of vital air and of known capacity, will live four times longer than if
the vessel contained atmospherical air. No remarkable difference is at
first perceived in the act of respiration, but if the animal remains long
immersed in the oxygen, his respiration becomes more frequent his cir-
culation more rapid, all the vital functions are executed with more ener-
gy. The lungs separate, by a. power inherent in themselves, the two at-
mospherical gases, and this process is effected by a considerable
power, for oxygen, in its combination with the blood, is, with difficulty,
separated from azote. Inifact, the blood, though in thin layers, becomes
dark, when exposed to the atmospherical air.

It is observed, that the purity of the air contained in the receiver, is
the more readily affected, as the animal placed under it is younger, more
robust, and his lungs are more capacious. Hence, birds, whose lungs are
very large, contaminate a considerable quantity of air, and consume more
quickly its respirable part. A frog, on the contrary, will remain a con-
siderable time, in the same quantity of air, without depriving it of
its oxygen.

* See APPENDIX, Note W,

„ The vesicular lungs of that reptile, as v/ell as of all oviparous quadru-
peds, are much more irritable than those of warm-blooded animals; they
appear to contract, at the will of the animal. The frog is without a dia-
phragm, attracts the air into its lungs, by swallowing it by a real process
of deglutition, as was proved by Professor Rafn, of Copenhagen, who
killed those animals by holding their jaws asunder for a certain time,
They reject the air by a contraction of the lungs, in the same manner as
in man, the bladder empties itself of urine.

In birds, whose diaphragm is equally membranous, and contains seve-
ral openings to transmit the air into the pulmonary appendices, the pari-
etes of the thorax are likewise more moveable than in man and quadru-
peds. Their pectoral muscles are more powerful, their ribs contain a
joint situated in the middle of those arches, which are completely ossified
in that class of animals ; and those two portions move on each other,
forming, at their point of union, angles more or less acute, according to
the distance of the sternum from the vertebral column.

A numerous class of cold red-blooded animals, viz. fishes, have no
lungs; the gills, which supply their place, are small penniform lamina,
generally four in number, situated on each side, at the posterior and late-
ral part of the head, covered over by a moveable lid, to which naturalists
give the name of operculum. The water which the animal swallows;
passes, when he chooses, through the parietes of the pharynx, which
contain several considerable openings, is spread over the gills and
the pulmonary vessels which are distributed in them, then escapes at the
auricular apertures, when the animal closes his mouth, and raises the
opercula. It is not known, whether the water is decomposed and yields
its oxygen to the blood which circulates in the gills, or whether the
small quantity of air that is dissolved in the water, alone serves to vivify
the pulmonary blood. The latter opinion seems the most probable, if it
be considered that a fish may be suffocated, by closing accurately the
vessel of water in which it is enclosed. The same result might, I con-
ceive be obtained, by placing the vessel under the receiver of an air-
pump, so as to exhaust it completely.

Respiration, which is completely under the influence of the brain, as
far as relates to its mechanism, is less dependent upon it, in regard to the
action of the lungs on the blood, and the combination of that fluid with
oxygen, which is the essential object of that function. The nerves,
however, have some influence on that function, as well as on the various
secretions, in which, according to Bordeu, they are of the first rate im-
portance. Dupuytren ascertained by his experiments, that the divi-
sion of the cervical portion of the eighth pair of nerves, did not sensi-
bly affect respiration; but the animal died with all the symptoms of as-
phyxia, when this nerve was divided on both sides. Death took place,
in the course of a few minutes, when the experiment was performed on
horses. Other animals did not die so soon after ; dogs, for instance, have
been known to live several days after the experiment. By interrupting
the communication between the lungs and the brain, we paralyze the for-
mer of these organs, and it ceases to convert the venous into arterial
blood. This fluid, conveyed by the pulmonary artery, continues of a dark
colour, when brought to the left cavities of the heart; the arteries con-
vey the blood without its having received its vivifying principle, in pass-
ing through the lungs which are paralyzed, by having their nerves tied
or divided. It is easy to conceive that all organs, for want of the stimu-

184

lus which determines their action, carry on their functions imperfectly^
and at last cease to act. The animal heat is likewise lowered a few de-
grees, ab was ascertained by the above mentioned physician, who thinks
he has established as a fact, that the ligature of the nerves of the lungs
does not destroy but weakens the Vital power, which enables them to take
up the oxygen, and to give out the carbonic acid. The brain, therefore,
possesses a double influence over the function of respiration; on the one
hand, it directs its mechanism, by means of the nerves which it sends to
the diaphragm, and to the intercostal muscles, and on the other hand, it
is through the nerves which arise from the brain, that the lungs have the
power of converting dark blood into arterial blood, which is the principal
phenomenon of respiration.

Experiments performed on the same subject, by Dr. Le Gallois, subse-
quent to those I just related, tend to throw some degree of uncertainty
on their results. Dr. Le Gallois repeated these experiments publicly, in
my presence, and at the society of the Medical School of Paris. After
dividing the two nerves of the eighth pair, in a guinea-pig, and after hav-
ing, by that process, brought on a state of usphyxia, he restored life and
motion to the animal, by opening the trachea at its interior part. The
blood of the carotids, which from red had become dark the moment the
nerves were divided, respiration is restored, and the animal lives seve-
ral days after the experiment. Whence does this difference arise ? does
the division of the eigth pair bring on asphyxia, by occasioning a spas-
modic constriction of the glottis, and by impeding, or even completely
obstructing the admission of the atmospherical air*?

LXXVIII. Of animal heat. The human body, which is habitually of
a temperature of between thirty-two and thirty-four degrees of Reau-
mur's thermometerf, preserves the same degree of warmth under the
frozen climate of the polar region, as well as under the burning atmos-
phere of the torrid zone, during the most severe winters and the hottest
summers. Nay, further, the experiments of Blagden and Fordyce in
England, and of Duhamel and Tillet in France, show, that the human
body is capable of enduring a degree of heat sufficient to bake animal sub-
stances. The fellows of the Academy of Sciences, saw two girls enter
into an oven, in which fruits and animal substances, were being baked ;
Reaumur's thermometer, which they took in with them, stood at 150 de-
grees; they remained several minutes in the oven, without suffering any
inconvenience.

All living bodies have a temperature peculiar to themselves, and inde-
pendent of that of the atmosphere. The sap of plants does not freeze,
when the thermometer stands only at a few degrees above zero; on placing
the bulb of a thermometer in a hole in the trunk of a tree, during winter,
the fluid sensibly rises. Now, three circumstances remain to be inves-
tigated : in the first place, what produces in living bodies, this inherent
and independent temperature ? In the second place, how do these bodies
resist the admission of a greater degree of heat, than that which is natu-
ral to them ? What prevents caloric, which has a perpetual tendency to a
state of equilibrium, from passing into a body surrounded by a burning
atmosphere? Lastly, how does a body which resists the influence of heat,

* See APPENDIX, Note W.

f Between 96 and 98 of Fahrenheit.

185

withstand equally, the destructive influence of an excessive degree of
cold*?

LXXIX. Caloric, in a latent state, or in combination with bodies, is
disengaged from them, whenever they assume a different state 5 when,
from a gaseous form they become liquid ; or, when from being liquid,
they become solid. No\v, living bodies are a kind of laboratories in
which all these changes are perpetually going on ; the blood which cir-
culates in every part of the human frame, is constantly receiving supplies
of fresh materials; from the thoracic duct which pours into it the chyle,
abounding in nutritious particles ; from respiration which imparts it to an
aeriform principle obtained from the atmosphere ; and even, in some
cases, from cutaneous absorption, through which different elements are
received into it. All these different substances carry along with them
into the blood, a certain quantity of caloric, which is- combined with
them, and which is disengaged during the changes which they undergo,
from the influence of the action of the organs, and gives out its caloric
to the parts among which it is disengaged. Of all the principles in the
blood, which have the power of communicating heat to the organs, none
furnishes a greater quantity than oxygen, which during respiration, com-
bines with the blood in the lungs. Gaseous substances, it is well known,
contain most combined caloric; their state of elastic fluidity, is entirely
owing to the accumulation of that principle, and they part with it, when
from any cause whatever, they become liquid. It is on that account, that
the heat of the bodies is greater, the more they have the power of im-
pregnating their fluids with a considerable quantity of oxygen from the
atmosphere. For the same reason, as was already observed, in animals
that have cellular lungs, and a heart with two ventricles, the blood is of
the same temperature, as in man ; and such animals belong as well as
man, to the great class of warm red-blooded animals; a class in which
birds occupy the first place, from the vast extent of their lungs, which
reach into the abdomen and communicate with the principal bones of the
skeleton. The capacity of the pulmonary organ of birds, is not the only
cause why their temperature is eight or ten degrees higher than that of
man : this increase* of temperature depends, likewise, on the greater
frequency of their respiration, and on the velocity of their pulse ; on
the quickness and multiplicity of their motions, and on -the vital activity
which animates them. In reptiles which have vesicular lungs, and a
heart with a single ventricle, whose respiration is slow, and performed
at distant intervals, the blood, though red, is of very inferior tempera-
ture to that of man. They have, from that circumstance, been called
cold red-blooded animals ; this numerous class includes fishes, which pos-
sess an organ supplying but imperfectly the office of lungs. In fishes,
the heart which has but a single ventricle, sends, it is true, to the
gills (the organ supplying the place of lungs is so called) the whole
of the blood ; that fluid, however, is but imperfectly vivified in the
gills, on account of the small quantity of air which can be taken
in during the act of respiration. Lastly, in white-blooded animals and
in plants, the combinations with the air being more difficult, the vital
energy less, marked, the temperature differs only by a few degrees, from

* See the remarks, in Api>£*jir\', Note Y, on the production of Animal Ifeat.

2 A

that of the atmosphere, and they do not endure heat or cold, so well as
the more perfect animals.

The lungs, as was before observed, consuming only a certain quantity
of air, there is no increase of temperature, however great the quantity
of oxygen contained in the atmosphere that is breathed 5 as a man who
should take a double quantity of aliment, could not receive more nourish-
ment, than if he contented himself with the quantity of food proportion-
ed to his wants ; for, as the digestive organs can extract only a certain
quantity of chyle, the quantity of recrementitious matter would only be
greater, if more than the due quantity of food were received into the
stomach. Hence the common saying, that nourishment comes from what
we digest, and not from what we eat.

The pulmonary organ may, however act on the air, with different de-
grees of power, 'in robbing it of its oxygen: and when the body becomes
of an icy coldness, in certain nervous and convulsive affections, this cold
may depend as much on the atony of the lungs, and on the spasmodic
condition of the chest, which, dilating with difficulty, does not admit the
air readily, as on the spasm and general insensibility of the organs, which
allow the blood to pass without affecting its component parts. It would
be curious to ascertain, whether the air expired from the lungs of a cata-
leptic, contains more oxygen, is less impaired, and contains a smaller
quantity of carbonic acid than the breath of a sound active adult. Per-
haps it would be found, that in catalepsy and other similar affections, the
blood does not part with its hydrogen and carbon, that it retains its co-
louring principles, and the different materials of the urine, which is void-
ed in a colourless and limpid state, insipid and without smell, and in the
condition of a mere serosity.

The temperature of the body is produced, not only by the pulmonary
and circulatory combinations ; it is besides developed in several organs,
in which fluid or gaseous substances become solid by parting with a por-
tion of their caloric. Thus digestion, particularly of certain kinds of
food, is an abundant source of caloric; the skin which is habitually in
contact with the atmosphere, decomposes it and deprives it of its caloric.
Lastly, caloric is produced and evolved in all parfs, whose molecules
affected by a double motion, in consequence of which they are incessantly
being formed and decomposed, by changing their condition and consist-
ence, absorb or disengage more or less caloric. The great activity of the
power of assimilation in children, is, no doubt, the cause of the habitually
high temperature, at that period of life. The temperature of the body
is not only one or two degrees higher at that period of life; but young
people, after death, preserve for a longer period the remains of vital
heat; or rather, as tonicity does not so soon forsake the capillary vessels,
life departing reluctantly, the combinations from which caloric is evolved,
continue some time, even after it is extinct. For the same reason, the
bodies of persons that have died suddenly, retain their warmth long,
while an icy coldness seizes the bodies of those who have died of linger-
ing disease, from the slow, gradual, and total abolition of the powers of
life.

Calorification, or the disengagement of animal heat, like nutrition, takes
place at all times and may be considered as belonging to all organs. It
•was of the utmost consequence, that the internal temperature of the
human body should be nearly the same at all times. For, let us, for one
moment, suppose that the temperature of the blood should rise to fifty

18?

degrees of Reaumur's thermometer, its albuminous parts would suddenly
coagulate, obstruct all the vessels, interrupt the circulation, and destroy
life. When, therefore, from an increased activity of the nutritive com-
binations, a greater quantity of heat is disengaged, the animal economy
parts with it, and if is taken up, in greater quantity, by the surrounding
bodies. This accounts for the equality of the temperature of the inter-
nal parts of the body, in old people, and in children, notwithstanding the
difference of their temperature externally. The difference consists in
this, that where most caloric is produced, most is given out; and though
the blood and urine in old people, as well as in the young, are at thirty-
two degrees, what a difference is there not, between the hot and pene-
trating perspiration which is poured in abundance from the child, and
the dryness and coldness of the skin in old people; between the sweet
and warm breath of the former, and the frozen breath of the latter!
Hence the opinion so generally received and of such antiquity, that old
people are benefited by cohabiting with the young. Thus we are told,
that David had a young virgin brought to him, that he might lie with
her, and get heat in his limbs that were stiffened with years.

If it be true, that in the very act of nutrition, which converts our fluids
into solids, there is disengaged a considerable quantity of caloric; the
motion of nutritive decomposition, by which our solids are converted into
liquids, must cause an equal quantity of heat to be absorbed. The ob-
jection is a very strong one, and not easily got over; it may be answered,
by observing, that all living bodies, from the instant of their formation,
contain a certain quantity of caloric which they retain, so that this double
process of acquiring heat and parting with it, the unavoidable result of
nutritive composition and decomposition, merely keeps up an equili-
brium, and maintains the same degree of temperature.

The blood which becomes saturated with oxygen, in the capillaries of
the lungs, parts with that principle, and disengages its caloric, through-
out the capillary vessels of the whole body, of which each organ must
set free a greater quantity, in proportion to the activity of the living prin-
ciple, and to the rapidity of the circulation. The parts through which
the greatest number of vessels circulate, perhaps give out most caloric,
and communicate a portion of it the organs, which receive but a small
quantity of blood, as the bones, the cartilages, Sec. It is easy to under-
stand, why an inflamed part, through which the blood circulates with
more rapidity, and whose sensibility and contractility are much increased,
is manifestly hotter to the feel of the patient and of the physician, though,
as was observed by John Hunter, a thermometer applied to the inflamed
part, shows a scarcely perceptible increase of temperature. He injected
into the rectum of a dog, and into the vagina of an ass, a strong solution
of oxymuriate of mercury. Acute inflammation came on, the swollen
mucous membrane formed, externally, a considerable projection. Blood
flowed from the torn capillaries, yet the thermometer rose very slightly,
only one degree of Fahrenheit's. But, however slight that increase of
heat in the inflamed part, it is very sensibly felt, on account of the ex-
treme sensibility of the organ, whose vital properties are all increased*.
The liveliness of impressions being proportioned to the degree of the
power of sensation, one need not wonder that the patient should experi-

* Whose capability to resist or proper tone is very much diminished — Godmau,

188

ence a sensation of burning heat, in a part in which the thermometer
indicates no increase of temperature, in which it cannot be perceived
even by the touch. I have just^elt a young man's hand, that is swollen
from chilblains; though the pain which he feels in it, seems to him to be
occasioned by an accumulation of caloric; his hand is colder than mine,
which is of the same degree of warmth as the rest of my body, and in
which I have no peculiar sensation. It may, therefore, be laid down as
an axiom, that the real or thermometrical increase of heat is inconside-
rable in inflammation, but that it is intensely felt, in consequence of the
increase of sensibility.

What is the reason, that during the cold fit of a febrile paroxysm, a
sensation of excessive cold is felt in a part in which no diminution of
heat can be discovered by the touch ? Whence comes the burning heat
which attends inflammatory fever (Kotvtroo-ty What is the cause of the
difference of the sensations attending the heat of erysipelas, bilious fe-
vers, and phlegmon, &c. These various sensations are owing to the dif-
ferent modifications of sensibility in these different diseases. Should
this explanation appear unsatisfactory, let it be recollected, that however
accurate the calculations may be, that have been made on the subject of
caloric, or of the matter of heat, the existence of caloric itself is hypo-
thetical, and that it is not known, whether caloric is a body, or whether
heat is merely a property of matter.

LXXX. If we now inquire into the causes which enable the body to
resist the admission of a degree of heat superior to that which habitu-
ally belongs to it, we shall be compelled to admit, in all living bodies, a
power by means of which they repel an excess of heat, and retain the
same temperature. Cutaneous perspiration, it is true, acts very power-
fully in lowering the temperature, and as this evaporation increases with
the temperature, it would seem as if this function sufficed to moderate
the heat of the body, and to restore the equilibrium.

It is a fact known since the time of Cullen*, that the evaporation of
fluids, or their solution in the air, is the most powerful means of cooling
bodies, and that the mercury in the bulb of a thermometer may be frozen
merely by moistening it with ether, spirits of wine, or any other volatile
substance, and then exposing it to a dry and warm air. This method is
equally successful in its application to the human body, and the hands
may be cooled to such a degree, as to feel benumbed, by being frequently
wetted with a spirituous fluid, and by being moved in a dry and renewed
air. But though cutaneous perspiration operates in a somewhat similar
manner, and though it may be ranked among the means which nature
employs to preserve the animal temperature in a nearly uniform state, it
must however be confessed, that it is not the only way in which this ob-
ject is accomplished, and that it does not satisfactorily account for this
phenomenon, for the evaporation of the fluids contained in dead animal
substances, doesnot prevent their being roasted on the application of heatf,

* This celebrated physician made this discovery about forty years ago, which has
•thrown much light on several physico chemical phenomena, and he published it in a
dissertation entitled, " Of the cold produced by evaporating fluids, and of some other
mean sot' producing cold," by Dr. W. Cullen.— 'Author's Note.

f These fluids are not renewed as fast as evaporated, in the roasting meat, which al-
ways takes place in the healthy living body. When the body is exposed to a high
t emperature, we find profuse perspiration without change of temperature in the system.

189

and besides, fishes and frogs have been known to live and retain their
temperature in mineral waters, nearly of a boiling heat*.

I thought it right to repeat these experiments, and with this view, I
placed living frogs in a vessel containing water at fifty degrees of tempe-
rature; and on taking them out, at the end of ten minutes, I ascertained
that they were not so hot as the liquid, nor as pieces of flesh which had
been put into it at the same time.

We cannot admit the opinion of Grimaud, that living bodies have the
power of producing cold ; for, as cold is merely the absence of heat, one
cannot allow a positive existence to a negative being.

Habit has a remarkable influence on the faculty which the body pos-
sesses, of bearing a degree of heat, much exceeding that which is natural
to it. Cooks handle burning coals with impunity; workmen employed
in forges, leave the mark of their feet on the burning and liquid metal,
at the moment when it becomes solid by cooling. Many, no doubt, re-
collect the too famous instance of a Spaniard, who became so general a
subject of conversation in Paris: this young man, in making his way
through a house on fire, perceived that the heat was less inconvenient to
him than he had imagined. He applied himself to bear with impunity,
the action of fire, and was enabled to apply to his tongue a spatula heated
red hot, and to apply the soles of his feet and the palms- of his hands on
a red hot iron, or on the surface of boiling oil. Nothing can equal the
absurdity and the exaggeration of the stories that were told of this man,
except the ignorance and the want of veracity of those who invented them.
The following is a correct statement of the feats of this man, who was
represented as incombustible and insensible. He passes rapidly along
the surface of his tongue, which is covered with saliva, a red hot spatula,
the action of which seems merely to dry it by bringing on an evaporation
of the "fluids with which it is covered. After carrying the spatula from
the base to the tip of his tongue, he brings it back again into his mouth,
and applies it to his palate, to which it communicates a part of its heat,
at the same time that it becomes moistened with saliva. This man,
having, in a public exhibition, carried on too long, the application of the
spatula, the caustic effects of its heat showed themselves, the epidermis
was detached, and found coiled, like the outer covering of an onion, in
the cloth which he used to wipe his mouth. He does not dip his hands
and feet in boiling oil, he merely applies to the surface of the fluid his
palms and his soles; and he repeats this frequently with only a short in-
terval between each application. When the experiment is carried on, for
a certain length of time, there is emitted a smell of burnt horn. No one
has yet observed, that though this man's hands are not callous, the palms
of these, and the soles of his feet are cushioned with fat. A thick layer
of fat, which is a bad conductor of heat, separates the skin from the sub-
jacent aponeuroses and nerves: this circumstance, to a certain degree,
account^ for his imperfect sensibility.

His £ulse during those experiments, was about a hundred and twenty;
the perspiration evidently increased, and sometimes copious. Every part

\Vhen fever is present, we have suppression of perspiration and increase of tempera-
ture. We therefore think it superfluous to look for more causes than are sufficient to
produce the effect, to say nothing of drawing inferences from changes produced on
dead matter, explanatory of the actions which take place in living bodies. — Got&nan.
* See Sonnerat's Voyage to the East Indies.

190

of his body possesses the ordinary degree of sensibility, may be destroyed
by the protracted application of caustic substances, and would be con-
sumed by fire, if applied for a sufficient length of time, and nitric acid
would infallibly destroy his tongue, if he took any into his mouth, as it
has been said he did. This man, therefore, in no one respect departs
from the known laws of the animal economy, but, on the contrary, affords
an additional proof of the influence of habit on our organs.

LXXXI. Before bringing to a conclusion this article on animal heat,
it remains for me to explain how the body resists cold, and preserves its
temperature, in the midst of a frozen atmosphere. This cannot be ac-
complished without an increase of activity in the organs, it is only by
augmenting the sum of the combinations by which caloric is disengaged,
that we can succeed in making up for the loss of that principle, so ne-
cessary to our existence. What is the reason that in cold weather di-
gestion is more active, (Hieme vero ventres aunt calidiores, Hipp.) the pulse
stronger and more frequent, and the vital energy greater? It is because
heat comes from the same source, and is produced by the same mechanism
as the nutrition of the organs; and that its evolution may go on increasing,
it is necessary that the secretions, nutrition, in a word all the vital func-
tions, should increase in the same proportion.

Observe, for a moment, a man who is exposed to a moderate degree of
cold, he feels more activity, more strength, and is more nimble, he walks
and exerts himself, the most violent exertions do not appear to him, labo-
rious, he struggles against the disadvantages of the debilitating influence;
and provided the cold is not excessive, and the body tolerably vigorous,
there is disengaged, within himself, a sufficient quantity of caloric to
makeup for the loss of that which is carried off by the air and the surround-
ing bodies. These general effects of cold are not disproved by what hap-
pens, when only a part of the body is exposed to it. Supposing the tem-
perature a few degrees below zero, there is felt, at first, a sensation of
cold much more inconvenient, caeteris paribus, than if it acted on a more
extensive surface. The spot on which the cold air acts, becomes affect-
ed with a painful sense of pricking, reddens, then inflames ; and in this
case, inflammation is evidently the result of a salutary effort ef nature
\vhich determines into the inflamed part, an excess of the vital princi-
ple*, so that the quantity of heat that is disengaged may correspond to
that which has been abstracted. The effort of this conservatory principle, is
more marked, than if the whole surface of the body were^at once exposed
to cold, because, acting wholly on a limited point, of small extent; it
operates with more intensity.

Beyond a certain degree, however, nature in vain struggles against
cold; if severe, and if the creature exposed to it, have not the power of
sufficient re-action, the part becomes purple and benumed from the loss
of its caloric, vitality ceases, and it mortifies ; and if the whole body is
equally exposed to the influence of cold, the person is benumed, feels a
stiffening of his limbs, stammers, and overpowered by an irresistiWe pro-
pensity, yields to a sleep which inevitably ends in death. By yielding
thus to the illusive sweets of a perfidious sleep, many travellers have pe-

* This pathology is incorrect. The part reddens and inflames, because its life has
been impaired and it is no longer able to bear the impulse given to the blood by the
heart. Hence it becomes engorged with blood, or in other words diseased. — Godman.

191

fished after losing their way, in the mountains of the old and of the new
world. Thus, two thousand soldiers of Charles the Twelfth's army pe-
rished, during a siege, in the severe winter of 1709.

To resist the effects of cold, a certain degree of strength and vigour is
therefore necessary , it is consequently very injudicious to recommend
the cold bath to very young children, to delicate and nervous women, to
persons whose constitution is not capable of a sufficient re-action. The
evil attending the injudicious use of this remedy in the cases that have
just been enumerated, justifies the apparently singular terms in which
Galen expressed himself: " Let the Germans, (says this first of physio-
logists) let the Sarmatians, those northern nations as barbarous as bears
and lions, plunge their children in frozen water; what I write is not in-
tended for them."

On the other hand, if it be recollected, that there is within us a power
of re-action, which increases with use, that motion strengthens our organs,
it will be readily understood, that cold acts as a tonic, whenever it is
not applied to such a degree, as to extinguish the vital power.

The manner in which enlightened physicians have, at all times, pres-
cribed the cold bath, shows that they were acquainted with this tonic effect
depending, not on the application of cold, which in itself is debilitating,
but on the re-action which it occasions. Hence along with the cold bath,
they are in the habit of recommending exercise, a generous wine, bark,
nutritious food, and an analeptic regimen, calculated to excite a salu-
tary re-action.

LXXXII. Animal heat is, therefore, produced by the combination of
our fluids and solids in the process of nutrition; it is a function common
to all the organs, for, as they all nourish themselves, so they all disen-
gage, more or less, the caloric combined with the substances which they
apply to their nutrition.

Though we are without precise information respecting the manner in
which a living body resists the admission of a degree of heat exceeding
that which is natural to it, one may consider cutaneous exhalation, which
is increased by the use of heating substances, as the most powerful means
employed by nature to get rid of the excess of heat, and to restore the
equilibrium.

Lastly, the body resists cold, because the organs being rendered more
active by cold, there is disengaged a quantity of caloric equal to that
"which is carried off by the air, or by the other substances with which the
body happens to be in contact*.

LXXXIII. The rapidity of the circulation of the blood through the
lungs, is equal to the velocity with which it flows in the other organs.
For, if on the one hand, the parietes of the right ventricle and of the
pulmonary artery, are weaker and thinner than those of the left ventri-
cle and aorta, the lungs, from their soft, easily dilated and spongy tex-
ture, are the most easily penetrated by fluids of all our organs.

* The animal economy resists a moderate degree of cold, and is even strengthened
by it, owing to the re-action of the vital influence. If, however, the degree of cold be
either absolutely or relatively great, the energy of the system is entirely overwhelmed
by its sedative operation. The effects of cold differ not only according- to its degree,
but also according* to the duration of exposure to it — to the state of the nervous
system previous to, or dining the exposure — and to the general condition of the body
at the time. — Copland.

192

The right ventricle sends into the lungs a quantity of blood, equal to
that which each contraction of the left ventricle propels into the aorta,
and it is not necessary to adopt the opinion of M. Kruger, that each con-
traction of the heart sends into the lungs, and into the rest of the body an
equal quantity of blood, for, in that case, the circulation would have
been much slower, the length of the lungs being much shorter than the
whole body. Nor need we say, with Boerhaave, that this circulation is
much more rapid, because the same quantity of blood returns by the
extremities of the pulmonary artery, and of all the other arteries of the
body.

The extensiou of the pulmonary tissue, the straightening of its vessels
are, no doubt, favourable to the circulation of the blood, but if the ad-
mission of air did not answer a different purpose, the circulation would
not be indispensably necessary. The blood flows from the right into the
left cavities of the heart, notwithstanding the collapse of the lungs and
the creases of their vessels. The air which penetrates, at all times, into
the lungs, supports their tissue and the vessels which are distributed to
it, so that even during expiration, the vessels are much less creased, than
has been imagined by several physiologists. But the changes produced
by the contact of the atmosphere; renovate this fluid, and fit it to re-excite
and keep up the action of all the organs, which require to be stimulated*
by arterial blood. If you make a living animal breathe de-oxygenated
air, the blood undergoes no change by its pulmonary circulation; the
left cavities of the heart are no longer duly irritated by this fluid, which
preserves all its ven.ous qualities; their action becomes languid, and
with it that of all the organs; and in a little while, it ceases altogether.
It is revived by introducing pure air, through a tube fitted to the trachea;
ail the parts seem to awake out of a sort of lethongic sleep; in which
they are again immersed, by depriving the lungs anew of the vital air.

The chyle, mixed in great quantity with the venous blood, undergoes,
in its passage through the heart and the sanguineous system, a more vio-
lent agitation ; its molecules are struck together, break on each other,
and, thus attenuated, become more perfectly intermingled: in its passage
through the lungs, a great part of this recrementitious fluid is deposited
by a sort of internal perspiration, in the parenchymatous substance of
these viscera. Oxy dated by the contact of tne air, re-absorbed by a mul-
titude of inhalent vessels, it is carried into the bronchial glands, which
are found blackened by what it there deposits of carbonic and fuliginous
matter. Purified by this elaboration, it returns into the thoracic duct,
•which pours it into the subclavian vein, whence it soon returns to the
lungs, to be there anew subjected to the action of the atmosphere ; so

* Some, hypercritics very strenuously object to the use of the term stimulation as ap-
plied to the 'action of the blood on the heart, and they urge that all stimulants disturb
or irritate, and, therefore, are unnatural, which the blood certainly is not. Neverthe-
less, the blood is the natural stimulus or excitant of the heart, and does in reality irritate
or disturb that organ under peculiar circumstances. It is true that the word stimulus
has by common custom a more enlarged meaning than its bare etymology would allow.
To those who are such sticklers for etymology as fixing significations, we may address
the following pertinent observation of the illustrious HARVKY . " De verbi autem ety-
mologia, non sum hie magnopere sollicitus ; neque enim pro jure pbilosophico esse cre-
dimus, ex verborum significatione illiquid de naturss opeiibus statuere, aut disceptationes
\medicas} vocare ad tribunal grammatical. Non est nempc tarn quaerendum quid vo-
cabuls. proprie significent, quam (VCOMOKO VTJLOO rsunpENTrn.'1' Kp. 1.—

193

that there is effected, through these organs, a real lymphatic circulation,
of which the object is to bring on the chyle to a higher degree of ani-
malization*.

LXXXIV. Of pulmonary exhalation. It will be remembered, that one
of the great differences between the blood of the arteries, and that of the
veins, consists in the great quantity of serum found in this last. It is in
the lungs that the separation of this aqueous part takes place, and that
its proportion is reduced, whether it be, that oxygen gives albumen and
gelatine a greater tendency to concrete, or that the serum, formed by the
fixation of oxygen throughout the whole extent of the circulatory system,
exhales from the arteries, and thus furnishes the matter of pulmonary
exhalation. It is scarcely possible to admit the combination of oxygen
with the hydrogen of the venous blood, and that water is thus formed
from its elements, as happens when storms are gathering in the high
regions of the atmosphere. If a similar process can be carried on in the
lungs, without producing deflagration and the various phenomena attend-
ing the production of aqueous meteors, it is probable, that it furnishes
but a small part of the exhalation 5 and that this humour, analogous to
the serum of the blood, exhales, completely formed, from the arterial ca-
pillaries ramified in the bronchiae and the lobular tissue of the lungs. It
is believed, that the quantity of the pulmonary exhalation is equal to that
of the cutaneous exhalation (four pounds in twenty-four hours.) These
two secretions are supplemental to one another: when much water
passes off by the pulmonary exhalation, the cutaneous is less, and vice
versa.

The surface, from which the pulmonary exhalation is given out, is
equal, if not superior in extent, to that of the skiji : exhalation and ab-
sorption are at once carried on from that surface, many nerves are dis-
tributed to it, and are slmost exposed in the tissue of the membranes
which are extremely thin. Are the miasmata with which the atmosphere
is sometimes loaded, absorbed by the lymphatics, which, it is well known,
have the power of taking up gaseous substances; or do they merely pro-
duce on the nervous and sensible membranes of the bronchiae, and of the
lobular tissue, the impression whence the diseases of which they are the
germ arise?

A part of the caloric which is disengaged in the combinations which
oxygen undergoes in the lungs, is taken up in dissolving and reducing in-
to vapour, the pulmonary exhalation which is the more abundant, accord-
ing as respiration is more complete. Pulmonary exhalation should be
carefully distinguished from the mucous matter secreted within the bron-
chiae and trachea, and which is thrown up by a forcible expiration, and
forms the matter of what we spit.

LXXXV. Of asjihyxia^. The term asphyxia, though merely indicating
a want of pulse, is applied to any kind of apparent death occasioned by

- * The two last sentences of this paragraph are rather hypothetical. We are not suf-
ficiently well acquainted with the use of the bronchial glands to assign them any posi-
tive office in the purification of the blood, nor do we see how much could be gained by
the kind of circulation through these organs, supposed by our author. We have always
understood that the change is effected while the blood is passing through the pulmo-
nary arteries, whence it is returned by the pulmonary veins to the left auricle, pre-
pared for the support and nourishment of the body — Godman.
f See APPEIS7D1X3 Note W.

2 B

194

an external cause and suspending respiration, as submersion, strangu-
lation, the diminution of oxygen in the air inhaled, Sec. The only dif
ference between real death and asphyxia, is, that in this last state, the
principle of life may yet be re-animated, \vhilst, in the other, it is com-
pletely extinct.

Asphyxia takes place .in drowning, because the lungs, deprived of air,
no longer impart to the blood which passes through them, the qualities
essential to the support of life. The water does not find its way into these
viscera; the spasmodic closing of the glottis, prevents its getting into
the trachea and its branches. Yet there is found a small quantity in the
bronchiae, after drowning, always frothy, because air has mixed with it,
in the struggles which precede asphyxia. If the body remain long under
water, the spasmodic state of the glottis ceases, water passes into the
trachea, and fills the lungs*. The anatomical examination of a drowned
body, shows the lungs collapsed, and in the state of expiration 5 the right
cavities of the heart, the venous trunks which terminate in them, and ge-
nerally, all the veins, are gorged with bloodf, whilst the left cavities and
the arteries are almost entirely empty. Life ceases in this kind of as-
phyxia, because the heart has sent to the different organs, and especially
to the lungs, no blood that is not deficient in the qualities necessary to
their action; and perhaps also, because the venous blood that is accu-
mulated in the tissues, affects them by its oppressive and deadly influence.
On that account, the best way of restoring the drowned to life, is to blow
pure air into their lungs. This is done by means of bellows adapted to
a canula introduced into the nostril; if a proper apparatus cannot be
procured, one might blow with the mouth into that of the drowned per-
son, or into his nostrils, by means of a tube; but air so expired, having
already undergone the process of respiration, contains a much smaller
quantity of oxygen, and is much less fitted to excite the action of the
heart. There remain several other less efficacious remedies, such as
friction, bronchotomy glysters, fumigations and suppositories, stimu-
lating errhines, and especially ammonia. Stimulants taken into the
mouth and stomach, the application of fire, bleeding, the bath, electrici-
ty, and galvanism.

The redness and lividity of the face, in persons who are hanged, had
led to the opinion that death, in such cases, was from apoplexy $ but it
appears that in the asphyxia from strangulation, as in that from drowning
death is caused by the interception of the air. To prove this, Gregory
performed the following experiment : he opened the trachea of a dog,

* The lungs£ from their Articular functions, are the organs which receive the -first
impressions ifcm a multitude of deleterious agents. The nerves supplying the lungs
being very extensively and intimately connected with those going to several organs of
sense, digestion, and assimilation, whicfc speedily suffer by sympathy with the part
originally injured, are frequently the least attended to when we are forming an opnion
as to the part first'operated on by the pgisoju We see this particularly exemplified in
jtliasma.tic fevers, in measles and small-pox, which have ensued from mere exposure te
infecteJVr ; and, indeed, in all diseases communicated through the atmosphere. —
Though the inhalation of impure air is confessedly the only mode in which such affec-
tions are produced, the first signs of disorder are so generally observed in the vascular
or digestive system, as to induce an entire forgetfulness of the great respiratory appa-
ratus which was first disarranged. — Godman.

| Hence the dark and livid colour of the skin and conjunctiva. This last membrane
is frequently injected with dark blood ; the very delicate veins of the brain are consi-
derably diluted, and this viscus is distended with venous blood — Copland.

195

and passed a noose round his neck, above the wound. The animal,
though hanged, continued to live and to breathe? the air entered and
came out alternately, at the small opening. He died, when the constric-
tion was applied below the wound. A respectable surgeon, who served
in the Austrian army, assured me, that he had saved the life of a soldier,
by performing upon him the operation of laryngotomy, a few hours be-
fore his execution.

Persons who are hanged may die, however, from dislocation of the cer-
vical vertebrae, and from the injury done, at the same time, to the spinal
marrow. Loui^, it is well known, ascertained, that of the two executioners
in Lyons and Paris, the one despatched the criminals he executed, by dis-
locating the head at its articulation with the neck, while the ether execu-
tioner destroyed them, by inducing asphyxia.

Of the different mephilic gases unfit for respiration, some appear to
bring on asphyxia, merely by depriving the lungs of the vital air necessa-
ry to the support of life, while others evidently affect the organs and the
blood which fills them, by their poisonous and deleterious influence.

One may mention, among the former, carbonic acid , in the asphyxia
occasioned by this gas, and which of all others is the most frequent, the
blood preserves its fluidity, the limbs their suppleness, and the body its
natural warmth, or even a greater degree of warmth, for some hours after
death; for, this kind of asphyxia occurring always in a very hot situation,
the body deprived of life, admits of an excess of caloric, such as would
have been resisted, if the vital power had not been suspended. However,
in this asphyxia, as in the preceding, the lungs remain uninjured ,• the
rig-lit cavities of the heart and the venous system, are gorged with a dark
but fluid blood. In the asphyxia, on the other hand, that is occasioned
by sulphureted or phosphureted hydrogen, Sec. or by certain vapours
whose nature is well understood, and which escape from privies, or from
vaults in which a number of dead bodies undergo putrefaction ; these are
frequently found in the lungs, dark and gangrenous marks, and death
seems the effect of a poison which is the more active, as its particles, ex-
ceedingly divided and in a gaseous state, are more insinuating, and affect
throughout its whole extent, the nervous and sensible surface of the
lungs*.

Inebriation seldom goes the length of bringing on asphyxia, it most
commonly produces a stupor readily distinguished from the affection
treated of in this article, by the perceptible, though obscure pulse, and
by the motions of respiration, though these are rare and indistinct. On
this account, M. Pinel, in his Noaografihie Philasophique, has placed inebri
ation and the different kinds of asphyxia, in two separate genera of the
class neuroses. It is conceivable, however, that the muscular irritability

* The celebrated Mr. Goodwin, not to mention others, concurs with our author, in
the opinion that the carbonic acid destroys life, and produces its lesser mischievous ef-
fects merely by the preclusion of oxygen. These writers, however, are undoubtedly
mistaken. Nothing is more clear than that this species of gas has a positive operation
en the animal economy. We will state a few facts in proof of it.

1. It has been shown, that animals die much sooner when exposed to the carbonic
acid, than when placed in vacuo, or when a ligature is applied to the trachea.

2. It has been shown, that frogs may be kept, without injury, for upwards of an hour
under water, but perish almost instantly if put into an atmosphere of fixed air.

3. It has been shown, that when the carbonic acid is combined' with water it very
speedily destroys fish.— Chapman,

196

may be so far impaired by the use of spiritous liquors, that the heart and
diaphragm might lose the power of contraction, which would bring on
complete asphyxia.

The glottis, through which the atmospherical air passes in its way to
the lungs, is so small, that it may be readily obstructed, when the epiglot-
tis rising at the moment of deglutition, the substance that is sw.allowed
stops at the orifice of the larynx ; a grape seed may produce this effect,
and it was in this manner, we are told, that Anacreon, that lovely poet of
the graces and of voluptuousness, came by his death. Gilbert, the poet,
died after a long and painful agony, from the introduction of a small key
into his throat, during a fit of insanity. A great eater, in the midst of a
feast, went into an adjoining room, and did not return, to the great sur-
prise of all the guests. He was found stretched on the floor, without any
sign of life. Help, given by ignorant people, was of no use. On opening
the body, a. piece of mutton was found fixed in the larynx, and complete-
ly stopping the passage of the air.

Sometimes a child is born, and shows no sign of life. When it is pro-
bable from the circumstances of the delivery, that there has been no or-
ganic injury decidedly mortal, it must be considered as a case of asphyx-
ia,* from weakness 5 and all means employed that are recommended in
such cases, especially blowing in air into the lungs, by means of a tube
introduced into the mouth or nostrils. It is thus, that the Prophet Elisha
restored to life the son of the Shunamite, as we are informed, in the se-
cond book of Kings, chapter the fourth. f

LXXXVI. Of certain phenomena of respiration, as sighing, sobbing,
yawning, sneezing, coughing, hiccup, laughing, fyc. When the imagination
is strongly impressed with any object, when the vital functions are lan-
guid, the vital principle seems to forsake all the organs, to concentrate
itself on those which partake most in the affection of the mind. When a
lover, in the midst of an agreeable reverie, sighs deeply, and at intervals,
a physiologist perceives in that expression of desire, nothing but a long
and deep inspiration, which, by fully distending the lungs, enables the
blood, collected in the right cavities of the heart, to flow readily into the
left cavities of that organ. The deep inspiration, which, is frequently

* The following case of'AspHTXiA in a child of six months old, and the manner in
which it was relieved, may be interesting to some of the profession. While at the
house of my friend, Mr. James Peale, some time since, one of the family came out to
Ihe door, where 1 was standing, and informed me with great consternation that the child,
(then labouring under pertussis,) had attempted to cough, and was suffocating, in conse-
quence of inability to discharge the phlegm. Hastily entering the room, I saw the babe
in the arms of the nurse, hanging forward, to all appearance dead ; its lips of a dark
purple, the eyes of the same colour, closed, and the eyeballs projecting very much. I
immediately applied my mouth over that of the infant, and made a strong effort to ex-
lumst the air from its lungs, closing the nostrils with one hand. The first and second ef-
forts were unavailing. Almost despairing of success, 1 placed my mouth over the mouth
and nostrils of the child, and made another violent inspiration, when to my great joy the
clot of phlegm was thrown out, and the breathing was gradually restored to its ordinary
state in a very few seconds. — God-man t

f The reader need not be reminded that French philosophers account for the miracles
related in Scripture, as they please, at least, there is no reference to such a mode of re-
storing life in the following sentence.

" And he went up and lay upon the child, and put his mouth upon his mouth,and his
eyes upon his eyes, and his hands upon his hands ; and he stretched himself upon the
child ; and the flesh of the child waxed warm." — 2 Kings, c. iv. 34.— Godman.

J97

accompanied by groans, becomes necessary, as the motions of respiration
rendered progressively slower, are no longer sufficient to dilate the pul-
monary tissue.

Sobbing differs from sighing, merely in this, that though the expiration
is long, it is interrupted, that is, divided into distinct periods.

Yawning is effected in the same manner ; it is the certain sign of ennui,
a disagreeable affection, which, to use the expression of Brown, may be
considered as debilitating or asthenic. The fatigued inspiratory muscles
have some difficulty in dilating the chest, the contracted lungs are not
easily penetrated by the blood which stagnates in the right cavities of the
heart, and produces an uneasy sensation, which is put an end to by along
and deep inspiration ; the admission of a considerable quantity of air is
facilitated by opening the mouth widely, by the separation of both jaws.
One yawns at the approach of sleep, because the agents of inspiration,
being gradually debilitated, require to be roused at intervals. One is,
likewise, apt to yawn on waking, that the muscles of the chest may be
set for respiration, which is always slower and deeper, during sleep. It
is for the same reason, that all animals yawn on waking, that the muscles
may be prepared for the contractions which the motions of respiration
require. The crowing of the cock and the flapping of his wings seem to
answer, the same purpose. It is in consequence of the same necessity,
that the numerous tribes of birds in our groves, on the rising of the sun,
warble, and fill the air with harmonious sounds. A poet then fancies he
hears the joyous hymn, by which the feathered throngs greet the return
of the God of light.

While gaping lasts, the conception of sounds is less distinct, the air, as
it enters the mouth, rushes along the eustachian tubes into the tympanum,
and the membrane is acted upon in a different direction. The recollec-
tion of the relief attending the deep inspiration which constitute gaping,
the recollection of the grateful sensation which follows the oppression
that was felt before, involuntarily leads us to repeat this act •whenever
we see any one yawning.

Sneezing consists in a violent and forcible expiration, during which the
air, expelled with considerable rapidity, strikes against the tortuous nasal
passages, and occasions a remarkable noise. The irritation of the pitui-
tary membrane determines, by sympathy, this truly convulsive effort of
the pectoral muscles, and particularly of the diaphragm.

Coughing bears a considerable resemblance to sneezing, and differs
from it, only in the shorter period of duration and the greater frequency
of the expirations ; and as in sneezing, the air sweeps along the surface
of the pituitary membrane, and clears it of the mucus which may be ly-
ing upon it, so the air, when we cough, carries along with it the mucus
contained in the bronchiae, in the trachea and which we spit up. The
violent cough, at the beginning of a pulmonary catarrh, the sneezing
which attends coryza, show that the functions of the animal economy
are not directed by an intelligent principle, for such an archseus could not
mistake, in such a manner, the means of putting a stop to the disease,
and would not call forth actions which instead of removing the irritation
and inflammation already existing, can only aggravate them.

Laughing is but a succession of very short and very frequent expira-
tions. In hiccup, the air is forcibly inspired, enters the larynx with dif-
ficulty, on account of the spasmodic constriction of the glottis; it is then
expelled rapidly, and striking against the sides of that aperture, occasions
the particular noise attending it.

*>

198

I shall on another occasion, explain the mechanism of sucking, oi'
panting, and of the efforts by which the muscles of the thorax fix the pa-
rietes of that cavity, so that it may serve as -a fixed point of the other
muscles of the trunk and the limbs.

Respiration is besides employed in the formation of the voice, but the
voice and the different modifications of which it is capable, will form the
subject of a separate chapter*.

LXXXVII. Of cutaneous perspirations. An abundant vapour is continu-
ally exhaling from the whole surface of the body, and is called the insen-
sible perspiration, when in a state of gas in the air which holds it in solu-
tion, it then eludes our sight; it isValled sweat, when in greater quantity
and in a liquid form. Sweat differs, therefore, from insensible perspira-
tion, only by the condition in which it appears, and it is sufficient for its
production, that the air should be incapable of reducing it into vapour,
whether from an increased secretion by the skin, or from the dampness
and consequent diminished solvent powers of the atmosphere. The insen-
sible perspiration is constantly escaping through the innumerable pores in
the parietes of the minute arteries of the integuments; it oozes in the in-
terstices of the scales of the skin; the air which immediately surrounds
our body, becomes saturated with it, and carries it off, as soon as it is re-
newed. There is the greatest resemblance, between the cutaneous pers-
piration and the pulmonary exhalation; both are mere arterial exhalations,
and the mucous membrane, which lines the canals along which the air is
transmitted, is a mere prolongation of the skin into these organs and into
the digestive tube. The surface from which the cutaneous perspiration
it exhaled, is not quite so considerable as that from which the pulmonary
exhalation arises, since it is reckoned at only fifteen square feet, in a man
of middle size. These two secretions are supplementary to each other ;

* The a&thor has neglected to notice the state of respiration during the most active
voluntary motions. Muscular exertion? especially when considerable, is preceded by
a long and deep inspiration, the glottis is closed*, the diaphragm and respiratory mus-
cles of the chest are contracted, and the reaction of the abdominal muscles cause the
contents of the abdomen to be pressed upon in all directions. At the same time that
the respiratory muscles are exerted, those of the face are associated, in the increased
action, in consequence of the latter receiving some nerves from the same class, (see
the notes in the APPENDIX on the different orders and functions of the voluntary
system of nerves) and the jaws are forcibly pressed together. By this action of the
muscles engaged in respiration, the chest is rendered capacious, and the strength is
greatly increased, because the trunk of the body is thus rendered immoveable in re-
spect to its individual parts, the muscles arise from fixed points, and consequently, wield
the members of the body, with their full energy. HALLER appears to be correct in
concluding that, under a" state of increased action of the muscles, the flow of blood b
comes greater towards the head, and thus the nervous energy is increased, and amply
generated, by means of this augmented flo'y, so as to keep up the muscular action for
a longer period than otherwise would be the case. During violent exertions, also, the
return of blood from the brain is in some degree impeded.

The physiological s.tate of muscular actions, as they are related to the mechanical
function of respiration, is very happily described by Shakspeare, where he makes the
fifth Henry encourage his soldiers at the siege of Harfieur : —
Stiffen the sinews,' summon up the blood,

Now set the teeth, and stretch the nostrils wide ;

Hold hard the breath, and bend up every spirit,

To his full height.

In vomiting also, and in the action of expelling the faeces and the contents of the blad-
der, the thoracic and abdominal muscles of respiration are brought into action.— Cop-
land.

199

the increase of the one is generally attended with a sensible diminution of
the other1; lastly, the mucous membrane of the intestinal canal, besides
secreting mucus exhales likewise a fluid which increases much in quantity,
when the cutaneous perspiration is languid, as is proved by the serous
diarrahceas so frequently occasioned by a suppressed perspiration. It
must be owned, however, that notwithstanding those analogies of structure
and function, in the skin and mucous membranes, there exists perhaps a
still more intimate connection between its actions and that of the organs
which secrete the urine; it has always been observed, that when this last
fluid is scanty, there is a greater cutaneous perspiration, and vice versa.

If we examine, with a microscope, the naked body, exposed during
summer to the rays of a burning sun, it appears surrounded with a cloud
of steam, which becomes invisible, at a little distance from the surface.
And if the body is placed before a white wall, it is easy to distinguish the
shadow of that emanation. We may, likewise, satisfy ourselves of the
existence of the cutaneous perspiration, by the following experiment:
hold the tip of the finger, at the distance of the twelfth part of an inch
from a looking-glass, or any other highly polished surface, its surface will
soon be dimmed by a vapour condensed in very small drops, which disap-
pear on removing the finger. One may, in this manner, ascertain that the
cutaneous perspiration varies in quantity, in different parts of the surface
of the body, for, on placing the back of the hand before a looking-glass,
the latter will not be covered by vapour.

No function of the animal economy has been the subject of more in-
vestigation, nor has any excited the attention of more accurate and inde-
fatigable physicians, than the secretion now under consideration. From
the time of Sanctorius, who, in the beginning of the seventeenth century,
published in his immortal work, " Medicina station," the result of experi-
ments carried on, for thirty years, with a patience which very few will
imitate, to that of Lavoisier, who jointly with Seguin, aided by the resour-
ces of the improved stateof chemistry, instituted an examination of the in-
sensible perspiration, we find engaged in this inquiry, Dodart, who in
1668 communicated to the Academy of Sciences, which had been founded
but a short time, the result of his observations at Paris, under a climate
different from that of Venice, where Sanctorious lived : — Keill, Robinson,
and Rye, who repeated the same experiments^! England and Ireland :—
Linnings, who performed his in South Carolina; and several physiolo-
gists of no less merit, as Gorter, Hartmann, Arbuthnot, Takenius, Win-
slow, Haller, &c. who all aimed at ascertaining, with more precision
than had been done by Sanctorius, the variations in the cutaneous per-
spiration, according to the climate, the season of the year, the age, the
sex, the state of health, or disease, the hour of the day, and the quantity
of other secretions.

According toSanctorius, of eight pounds of solid and liquid aliments
taken in twenty-four hours, five were carried off by the perspiration, and
only three in excrement and urine. Haller conceives this calculation to
be exaggerated : Dodart, however, carried it still further, and maintained
that the relation of the perspiration to the solid excrements, was as seven
to one.

In France and in temperate climates, the quantity of the cutaneous per-
spiration, and of the urine, is nearly the same; it may be estimated at be-
tween two and four pounds in the twenty-four hours. We perspire most
in summer, and void most urine in winter. The perspiration, like every

200

ether secretion, is in smaller quantity during sleep, than while we are
awake; in old age than during infancy, in weak persons, and in damp
weather, than under the opposite circumstances.

The perspiration may be said to be in a compound ratio of the force
with which the heart propels the blood into the minute capillary arteries,
of the vital energy of the cutaneous organ, and of the solvent powers of
the atmosphere. The strongest and most robust men perspire most ;
some parts of the skin perspire more than others, as the palms of the
hands, the soles of the feet, the arm-pits, &c. When the air is warm,
dry, and frequently renewed, cutaneous perspiration is greater, and the
necessity of taking liquid aliment is more urgent, and more frequently ex-
perienced ; in summer, as every body knows, a profuse perspiration is
brought on by passing from the heat of the sun into the shade; and, on
no occasion is a copious sweat more easily brought on, than by taking
exercise in summer, when on the approach of a storm, the atmosphere,
containing a small quantity of vapours, and warm from the rays of the sun,
which shows itself, now and then, surrounded by the clouds, is little capa-
ble of dissolving the insensible perspiration.

The skin may be covered with sweat, without any increase of the cuta-
neows perspiration; this may happen from dampness in the air, or from
its being imperfectly renewed. It must be owned, however, that sweat-
ing is more frequently occasioned by an increase of the insensible perspi-
ration, and that the warmth of the bed which excites it, acts by increasing
the power of the organs of circulation and the energy of the cutaneous
system. The body is weakened by sweating, which is seldom the case
with the insensible perspiration. A profuse sweat is attended with a
very speedy exhaustion ; thus, in hectic fever, in the suelte (sudor angli-
cus) and other affections, equally dangerous, it is the cause of a wasting
almost universally fatal.

The matter of the insensible perspiration and of the sweat, is, in great
measure, aqueous. Like the urine, it holds in solution several salts, also
the volatilized recrementitious matter of animal substances, sometimes
even acids, as in the case in which Berthollet detected the phosphoric
acid in children affected with worms, in pregnant women, in nurses, from
whom there exhales an odour manifestly acid. It may contain ammonia,
and, on certain occasions, the smell enables us to discover that alkali, in
the sweat or perspiration.

The air which constantly surrounds our body, does not merely dissolve
the aqueous vapour which arises from it, but several physiologists very
reasonably conjecture, that the oxygen of the atmosphere may combine
with the carbon of the blood brought to the skin by the numerous vessels
which are sent to it, and likewise with the gelatine forming the substance
of the rete mucosum of Malpighi.

The experiments of Jurine, of Tin gray, and of several other naturalists,
show that carbonic acid is constantly formed on the surface of the skin, so
that the skin may be considered as a supplementary organ to that of re-
spiration 5 and in that point of view, one may compare to it, the mucous
membranes which are in contact with the atmospherical air in the nasal
fossae, and in the intestinal canal which they line.

The cutaneous perspiration is, likewise as was before mentioned, a
powerful means of cooling the body, and of keeping it while living, in an
uniform temperature. The water which is exhaled from the whole sur-
face of the body, carries offfrom it, in passing into a vapour, aconsidera-

201

ble quantity of caloric; and it is observed that every thing which increases
the production of caloric, gives rise to a proportionate increase of the cu-
taneous perspiration and of the pulmonary exhalation, so that a constant
equilibrium being kept up between its production and escape, the animal
warmth always remains nearly the same*.

To conclude, the extremities of the nerves of our organs of sensation,
are ail moistened by a fluid varying in quantity, and which maintains
them in a softened state, favourable to the exercise of their functions. It
was likewise necessary, that the membrane in which the sense of touch
resides should be habitually kept moist by a fluid that should penetrate it
throughout : this use of the insensible perspiration is not less important
than the preceding, on which physiologists have bestowed most atten-
tion.

CHAPTER V.

OF THE SECRETIONS.

LXXXVIII. Of the animal fluids. The animal fluids were formerly
divided into recrementitious^ excrementitious, and excremento-recrementi-
tious ; this division, founded on the- uses to which the fluids are subser-
vient 5 is preferable to any that has since been adopted, and in which
they are ranked according to their nature.

The first class remain in the body, and are employed in its autrition
and growth ; such as the chyle, the blood, the serosity which lubricates
the surface of the pleura, of the peritoneum, and of the other membranes
of the same kind. The second kind are ejected from our body, and can-
not remain long within it, without danger; such as the urine, the matter
of insensible perspiration and of sweat. Lastly, those of the third class
partake of the nature of the two preceding, and are, in part, rejected,
while another part is retained and employed in the support and growth
of the organ: this is the case with the saliva, the bile, the mucus of the
intestines, Sec. If one affected to be very minutely scrupulous, one
might consider all the animal fluids as recremento-excrernentitious. The
chyle and the blood, which are so very nutritious, contain an abundance
of heterogeneous and excrementitious parts ; the urine, which of all our

* If transpiration be restrained or stopped, and if the causes productive of heat act
with intensity, it would appear that the temperature of the surface of the body rises
some degrees ; hence the reason that the heat is so distressing in those diseases which
are characterized by dimi?iished transpiration, and in which the dryness of the skin is
so remarkable, as erysipelas, erythema, &c. M. M. Berger and Delaroche have sup-
posed that they have seen, when the air of a room is saturated with humidity and ren-
dered very warm, that the human body exposed to this atmosphere acquires a higher
temperature than is natural to it, the cutaneous and pulmonary transpiration either
being altogether arrested or imperfectly performed. For farther observations on this
subject, see APPENDIX, Note Z.— Copland.

202

fluids is that which may, with most propriety, be termed such, contains?
likewise, aqueous parts, which, while it remains in the bladder, the
lymphatics absorb and carry into the mass of the fluids.

Of all the modern divisions, Fourcroy's is the best; Vicq-d'Azir ac-
knowledged its superiority over that proposed by Haller, in his Physiolo-
gy. Fourcroy admits six classes of fluids : 1st those which hold salts in
solution, as the sweat and urine ; he gives the name saline to such fluids :
2nd, inflammable oily fluids, all possessing a certain degree of consistence
and concrescjbility, as fat, and the cerumen of the ears, &c.; 3d. the sa-
ponaceous fluids, as the bile and milk; 4th, the mucous fluids, as those
which lubricate the internal coat of the intestinal canal ; 5th, the albu-
minous fluids, among which one may rank the serum of the blood ; 6th,
thefibrinous fluids, containing fibrina, as the fluid lust mentioned*.

In proportion as we advance in our knowledge of animal chemistry,
the defects of these divisions become more, and more evident. In short,
the animal fluids are so compound, that there is not one which does not,
at once, belong to several of these classes, arid whose prevailing element
is not sometimes exceeded in quantity, by materials which commonly
form but a small part of them.

LXXXIX The blood is the reservoir and the common source of the
fluids; these do not exist in the blood, with the qualities which character-
ize them, unless, after having been previously formed by the secretory
organs, they have been absorbed by the lymphatics, and conveyed, with
the chyle and lymph, into the circulatory system. Let us briefly attend
to its nature, although this belongs more especially to the department of
chemistry. The blood is red in man, and in all warm-blooded animals,
and even in some whose temperature is not very different frem that of the
atmosphere, as in fishes and reptiles. This colour, of a deeper or lighter
shade, according as the blood is drawn from an artery or a vein, varies
in its degree of intensity, according to the state of health or weakness.
It is of a deep red in strong and active persons, pale and colourless in
dropsical patients, and whenever the health is weak. By its colour
one may judge of all its other qualities. Its viscidity is greater, its sa-
line taste more marked, its peculiar smell stronger, when its colour is
deep. This colour is produced by a prodigious number of globular mo-
lecules, which move and float in an aqueous and very liquid fluid. When
the blood is pale, the number of these molecules diminishes, they seem
to be dissolved in cachexiae.

The microscope, which affords the only method of perceiving them,
does not enable one to determine their bulk and their figure. Leeu-
wenhoek, who brought forward the idea of their being so minute, by his
calculation that they were one millionth part of an inch in size, thought
them spherical. Hew son says they are annular, and have an opening
in their centre. Others compare them to a flattened lentil, with a dark

* BERZELIUS distinguishes the fluids formed from the blood into secretions properly
so called, and excretions, or those which are directly discharged from tiie body The
former class of fluids is destined to perform a farther office in the animal economy-
all of these are alcaline ; they are the bile, the saliva, and the fluid which is secreted
on the mucous and serous surfaces. In the latter division, acids predominate, the ex-
cretory fluids embrace the urine, the cutaneous and pulmonary transpiration, and the
milk. MAGKXDIE divides the secretions into exhalations, folUcular secretions, and glandu^
far secretions. See APPENDIX, Note A A, for farther observations on this subject,—
Copland.

203

spot in the middle. They are solid, and formed by a nucleus or red
point, covered over by a membranous vesicle, which appears to be rea-
dily formed and destroyed.

XC. The blood, wheti no longer in the course of the circulation, and
on being received into a vessel, parts with its caloric, and exhales, at the
same time, a powerful smell, a gas to which, according to some physio-
logists (Moscati, Rosa, &c.), it owes its vital properties, and the absence
of which is attended with a loss of its vitality ; so that its analysis cannot
furnish facts applicable to the explanation of the phenomena of health
and disease. This odour, extremely strong in carnivorous animals, is
very distinguishable in man, especially in arterial blood. I remember
retaining it, a whole day in my throat, after removing the dressings, and
suppressing a hemorrhage, occasioned by a relaxation of the ligatures, a
-week after the operation for popliteal aneurism. Unless by agitation it
is prevented from coagulating, as it cools, its consistence increases, and,
on being laid by, it separates into two very different parts, the one aque-
ous, more or less red, heavier than common water, and evidently saltish ;
this is called the serum, consisting of water, in which are dissolved albu-
men, gelatine, soda, phosphates, and muriates of soda; nitrate of potash,
and muriate of lime.

Serum, though bearing some analogy to the albumen of egg, differs
from it, in forming on coagulating, a less solid and less homogeneous mass.
The albumen is evidently mixed with a portion of transparent gelatine,
not coagulable by heat. Albumen has so great an attraction for oxygen,
that it is fair to presume, that the serum absorbs oxygen and combines
with it, through the very thin parietes of the air cells of the lungs, and
that it gives to the arterial blood that spumous appearance which is one
of its distinguishing characters. This oxidizement, and the fixation of
the caloric which accompanies it, equally increase its consistence. It
does not, however, coagulate ; because it is kept in perpetual motion by
the circulatory action, and is diluted by a sufficient quantity of water;
because the animal temperature, which never exceeds thirty-two or thir-
ty-four degrees, cannot give a solid form to albumen, which coagulates
only at fifty degrees of Reaumur's thermometer; and lastly, because as
serum contains a certain quantity of uncombined soda, which enables it
to turn green vegetable blues, this alkali concurs in keeping the albumen
in a dissolved slate, which it renders fluid, when it has been coagulated
by the acids, by heat, or by alcohol.

Amid the serum, and on its surface, there floats a red cake, spongy,
and solid, (insula rubra} which, by repeated washing, may be separated
into two very distinct parts. The one is the cruror or the colouring mat-
ter which mixes with the water; it is a more highly oxygenated and more
concrescible albumen than that of the serum; it holds in solution of
soda, as well as phosphate of iron, with an excess of iron*.

* It is a more oxygenated and a more coagulable albumen than that of the serum.
The colouring part of the blood, when incinerated, after giving off a considerable quan-
tity of ammonia during the combustion, leaves ashes which, according- to BEHZELIUS,
are only a hundreth part of its weight, and which contains 56 parts of the oxide of iron,
8£ of the phosphate of lime, a little magnesia, 17£ parts of lime, and 16£ of carbonic
acid. The oxide of iron is neither found in the ashes of the coagulable part of tae se-
rum, nor of those of the fibrine. BERZELITJS, however, farther informs us, that the
serum, although able to dissolve a small portion of the oxides of iron, but not of its

£04

other is a solid and fibrous substance, which, after being repeat-
edly washed, has the appearance of felt, the filaments of which cross
each other, are extensible and very elastic. This third part of the blood
is called fibrina^ it is very similar in its nature to muscular fibre, and like
it, gives out, on distillation, a considerable quantity of carbonate of am-
monia. Fibrina does not evist in the blood in a solid form, but in a state
of solution, and combined with the other constituent parts of the fluid,
as is indicated by the appropriate expression of liquid flesh (chair con-
lante) first used by Bordeu, in speaking of the blood.

XCI. If the blood be exposed to the action of fire, if it be calcined and
reduced to powder, and if this pulverized substance be exposed to a
magnet, the presence of iron will be manifestly seen by the magnetic at-
traction. Authors do not agree in their accounts of the quantity of iron
contained in the blood. Menghini says, there is one part in the hundred ;
others, that it is in the proportion of 1 to 303$ so that it is probable, that
this constituent principle of the blood, like all the materials of our fluids,
may vary in quantity, according to different circumstances.

Blumenbach justly observes, that iron is found only in calcined blood;
that none is to be found if it be slowly dried. This peculiarity is no
longer surprising, since Fourcroy has shown that iron existed in the
blood, in combination with the phosphoric acid, and formed with that
acid a phosphate of iron, with an excess of its base. - This salt becomes
decomposed by calcination, the iron is set free, and is acted upon by the
magnet. Physiologists attribute the colour of the blood to the presence
of the oxide of iron in that fluid.

It has been the received opinion, that the red colour of the blood is
owing to the presence of phosphate of iron, which, being conveyed, of a
white colour into the blood, along with the chyle, meets with the pure
soda, by which it is dissolved, and from which it receives its colour; the
colour of the blood is, likewise, owing to the oxulizement of the metallic
portion, which is in very considerable quantity in that salt. This solu-
tion of the phosphate of iron by soda, the oxidizement of the excess of
iron, and the absorption of oxygen by albumen, constitute, in an especial
manner, hematosis or sanguification, which is principally carried on in the
lungs*.

The respective proportion of the three parts into which the blood sepa-
rates spontaneously, varies considerably. The serum constitutes about
one half or three fourths of the fluid; the colouring matter and fibrina
are in inverse ratio of the serum, and it is observed, that the more bril-

phosphates, does not acquire a red colour by this weak solution, -and that he has
neither detected iron nor lime in the entire blood, although both are so abundant in its
ashes. He therefore concludes, that the blood contains the elements only of the phos-
phate of iron, and of lime and magnesia, and of the carbonate of lime, united very dif-
ferently from their combination of these salts. Nor is it unlikely that these salts are
formed during incineration, from the presence of the elements of "their respective bases
in the blood, either in an uncombined, or in a differently combined form, the other
elements being partly furnished by this fluid also, and partly by the atmosphere, during
the incineration. — Copland.

* This opinion of FOURCROY respecting the source whence the blood acquires its red
colour, has, since his time, been adopted by some, and combated by other physiologists.
It is now entirely abandoned, because it i"s known that the colouring part of this fluid
may be obtained separately, and entirely exempt from iron. This colouring1 portion of
the blood, according to M. VAUQ.UBLIX, does not change its colour when treated with
gallic acid— a farther proof that it contains no iron. — Copland.

205

llant and red the colour of the blood, the greater the proportion of the
fibrous part. The pale, aqueous, and colourless blood of a dropsical
patient contains very little fibrina. In putrid or adynamic fever, in which
bleeding, as is universally known, is improper, I have sometimes seen the
blood containing but a small portion of fibrina, and very slow of coagu-
lating: its texture seemed to suffer from the affection under which the
muscular organs were evidently labouring. In inflammatory diseases,
on the contraryyRhe plastic power cf the blood is augmented; the fibrina
is in greater quantity, even the albumen coagulates spontaneously, and
forms a crust above the serum, which is always in smaller quantity*.

XCIL Of the changes on the blood. The fluids not only undergo changes
in their composition, in their qualities and nature, when the action of the
solids is itself altered ; but even the absorbent system may introduce into
the mass of our fluids, heterogeneous principles, evidently the cause of
several diseases. In this manner, all contagions spread; the virus of
small-pox, of syphilis, of the plague, Sec. Thus, in time, the habitual
use of the same aliment produces in our fluids a crasis or peculiar consti-
tution, which has, on organized solids, an influence acting even on the
mindf.

A purely vegetable diet conveys into the blood, according to Pythago-
ras, bland and mild principles: this fluid excites the organs in a mode-

* According1 to Mr. BRA^DB and Sir E. Hoiwt, both venous and arterial blood contain
carbonic acid in the proportion of two cubic inches of the gas for each ounce of blood.
This acid disengages itself immediately, when a portion of the warm blood is placed in
an air-pump. See APPENDIX, Note B B, for farther remarks respecting1 the blood. —
Copland.

j- These opinions of our author are evidently borrowed fronx.the humoural pathology.
Of this system, much is still retained, and especially by me French pathologists. We
believe that the changes wrought in the fluids are wholly produced through the inter-
vention of the solids. Not thellightest proof exists of their being vitiated by the intro-
duction of '• heterogeneous principles," much less, that the mixture is the "cause of
several diseases." It is manifest, that every portion of the absorbent system has the
power, in a very great degree, of digesting and animalizing the substances which are
taken up. This property of the absorbents is a provision of nature, to prevent noxious
substances from penetrating into the circulation unchanged. In most instances, they
are fully adequate to this end. Where they are not, the substance passes to the firs't
lymphatic gland, which takes on inflammation and intercepts its further progress, as in
the case of bubo. In this respect, therefore, the conglobate glands may be considered
as sentinels guarding the exterior approaches of the body.

We are not ignorant that some of the properties of certain substances, when absorbed,
display themselves in the secretions and excretions, as the odour of garlic, the colouring
matter of madder, &c. &c. But it does not hence follow, that they entered the circu-
lation unchanged.

Experiments, indeed, prove quite the contrary, as neither one nor the other can be
detected in the serum of the blood. It seems to us most probable, that the process of
assimilation, whether performed by the chylopoietic viscera, or by the absorbent appa-
ratus, completely decomposes all substances subjected to its influence, and, however
various in their principles, reduces them to one 'homogeneous fluid, bland and inope-
rative in its nature, or in other words renders it fit for the purpose of nutrition. But,
in the excretions or secretions, being removed beyond the sphere of the vital powers,
chemical action takes place, by which those substances are in part or entirely regene-
rated.

Whether the particular explanation offered by this hypothesis be received or not, the
fact at least must be acknowledged, that no substance in its active condition does enter
into the circulation, since experiments have shown, that however mild the fluid may be,
either milk or mucilage, oil or pus, it cannot even in the smallest quantity be injected
directly into the blood vessels without occasioning the most fatal consequences. As
regards the operation of substances on the Jiving system, we do not think it at all ne«

206

frate degree, and this check over the physical excitement, facilitates the
observance of the laws of temperance, the original source of all virtue.
These observations of ancient philosophy, on the influence of regimen,
have, doubtless, led their authors to exaggerated inferences, but they
should not be considered as altogether unsupported. The carnivorous
species are marked by their strength, their courage, and their ferocity;
savages who live by hunting, and who feed on raw, bloody, and palpitating
flesh, are the most ferocious of men; and, in our country, in the midst
of those scenes of horror which we have witnessed, and from which we
have suffered, it was observed, that butchers were foremost in the mas-
sacres, and in all the acts of atrocity and barbarity. I know that this
fact, which w*s uniformly noticed, has been explained by saying, that
the habit of slaying animals, had familiarized them to shed human blood.
But though I do not deny the existence of this moral cause, which cer-
tainly operates, I think I may add to it, as a physical cause, the daily
and plentiful use of animal food, the breathing an air filled with emana-
tions of the same kind, which they inhale, and which contribute to their
corpulence, which is sometimes excessive.

As the plasticity and concrescibility of the blood are diminished in as-
thenic diseases, or of debility, as putrid fevers and scurvy, two causes
may be assigned for the hemorrhages which come on in those diseases,
\iz. the relaxed state of the vessels and the dissolution of the blood. In
scurvy, the tissue of the capillaries is relaxed, its meshes enlarged, red
blood passes into them, transudes through their parietes, and forms scor-
butic spots. I have sometimes seen those ecchymoses or sanguineous
cutaneous transudations, extend under the skin of the whole of one lower
extremity. Petechiae, in putrid fever, are formed in the same manner,
and depend, likewise, on the relaxation of the minute vessels, and on the
greater fluidity of the blood, whose molecules are less coherent, and
more readily separated from each other.

eessary to resort to the circulation as a medium through which it is effected. By refer-
ring it to that law of the animal economy termed sympathy or consent of parts, we have
a rationale far more consistent with those views "derived from the present improved
state of our knowledge.

Conformably to this theory, when a substance either medicinal or poisonous is applied
to a susceptible portion of the body, externally or internally, an action is excited which
is extended, more or less according" to the diffusibility of the properties of the substance,
or the degree of the sympathetic connexion which the part may have with the body
generally. Thus a set of Actions is raised, every one of which is precisely similar, pro-
vided they are. confined to the same system, by "which is to be understood, parts of an
identity of structure. If, however, the chain runs into other systems, it loses its homo-
genous character, the actions being modified according to the peculiar organization
of the parts in which they may take place.

To illustrate the more distinctly our meaning, we will state a very familiar case. By
inserting a particle of variolous matter under the skin, local irritation is created : in a
few days tins action becomes diffused, and a fever ensues, which after a short continu-
ance throws out an eruption, each pustule of which is alike, because the surface of the
body is of a uniform structure, containing exactly the same sort of virus as the primary
or parent pustule. It is in this way, that morbid motion distributes itself. When dis-
eases arise from a point, as in fact all diseases do, but more strikingly those occasioned
by inoculation, the matter introduced is not infinitely divided and spread over the
body, but the action which that matter had originally excited. These are general
principles, which apply to the system in every condition, and explain the modus ope-
randi of medicines as well as of' the causes of disease. Whatever, in short, operates
on the living frame, is obedient to the same laws. The spot first acted upon, is th<»
focus from which is irradiated the more diffused impressions.— Chcpmnu.

207

In the summer of the year 1801, I amputated the arm of an old man oi'
sixty, on account of a corroding- and varicose ulcer, which for thirty
years had occupied a part of the fore arm, and extended lo the elbow.
All who were present at this operation, observed that the blood which
flowed from the arteries, was not nearly so red as that from, the arteries
of a young man, whose thigh had just been taken off, on account of a
scrophulous caries of the leg; that the venous blood was entirely dis-
solved, purple, and similar to a weak dye of logwood. This blood did
not coagulate, like that of the young man, it became fluid, and was con-
verted into a serum containing a few colourless clots.

Those who have endeavoured to find, in the changes undergone by
the blood and the other fluids, the cause of all diseases, have fallen into
us serious blunders as the determined solidists, who maintain that all
diseases arise from a deranged condition of the solids, and that every
change in the condition of the fluids is a consequence of that derange-
ment. The believers in the Immoral pathology, have certainly gone too
far ; they have admitted that the animal fluids might be acid^ alkalescent,
acrimonious, while we have no proof whatever that they ever do under-
go such changes. The solidists have, likewise, gone much beyond the
truth, in saying, that every primitive change in the condition of the fluids
is imaginary, and that the doctrine of humoral pathology is without foun-
dation. Stahl relates* that the blood of a young woman, who was bled
during a fit of epilepsy, was absolutely coagulated, as if that fluid had
partaken in the rigidity affecting the muscular organs. Some authors say
they have met with the same appearance;! have, however, never been
able to discover any sensible difference between the blood of an epilep-
tic patient and of any other person of the same constitution, of the same
age, and living on the same regimen ; and it should be considered, that to
make a just comparison of our fluids, it is necessary that every thing
should be alike in the persons from whom they are taken, with the ex-
ception of the difference of which we are to judge. In fact, the blood
has not the same appearance, and does not coagulate, in the same manner,
when taken from a child, a woman, or an old man; from a man who lives
abstemiously, or from one who lives on a full dietf.

After enumerating the changes which the blood undergoes, one might
speak of those which affect the fluids that are formed from it, one might
attend to the greenish, leek colour, and sometimes even darkish appear-
ance of the bile, which is not always of the same degree of bitterness ;
the liquid state of the urine, which is voided colourless, without smell or
flavour, after a fright, or during ihe convulsive fits of hysterical women ;
the foetid smell and the viscidity of the saliva, when the salivary glands
are under mercurial influence ; the milky state of the serum which lubri-
cates the parietes of the abdomen and of the viscera which it contains,
after inflammation of the peritoneum $ changes which almost universally

* Theoria medica vera, page 678.

t As to the humoral pathology, in the present state of our knowledge, we cannot
help regarding it as unnecessary and unphilosophica'. Allowing all that may be asked,
in consequence of the latest experiments, we remain persuaded that the changes pro-
duced in the blood are secondary to previous alterations in the blood-making organs.
Hence we prescribe for the digestive system, without reference to the " humours," sure
that " vitiated fluids" will not long trouble us» after we have excited the nervous sys-
tem to a proper degree. — Gedman,

208

depend on a derangement of action in the secretory organ, and sometimes*
likewise, on the general condition of the fluids; for, a gland cannot se-
crete a fluid endowed with the qualities which peculiarly belong to it,
unless the blood furnish it with the materials of secretion, and unless it be
in a state to bring about a due combination of their particles. When we
come to the article of accidental secretions, we shall speak of some, of
those disorders of the fluids, depending on a depraved condition of the
secretory organs*.

XC1II. On the transfusion of blood. In the midst of the disputes to
which the discovery of the circulation gave rise, some physicians conceiv-
ed the idea of renovating completely the whole mass of the fluids, in per-
sons in whom they might be vitiated ; by filling their vessels with the
blood of an animal, or a person in good health. Richard Lower, known
by his work on the heart, first practised it on dogs, in 1665. Two years
afterwards, transfusion was performed at Paris on men : it excited the
greatest expectations : it was thought, that by this process, called trans-
fusing surgery (chirurgie transfusoire,) all remedies would be superseded,
that henceforth, to cure the most serious and inveterate diseases, it would
be necessary merely to tranfuse the blood of a strong and healthy man
into the veins of the diseased ; nay, they went so far as actually to imagine
they might realize the fabulous fountain of Jouvence ; they expected no
less, than to restore youthful vigour to the old, by infusing into them the
blood of the young, and thus to perpetuate life. All these brilliant chime-
ras soon vanished, some underwent the experiment, without any remark-
able effects from it, others were affected with the most violent delirium ;
a lad of fifteen lost his senses, after suffering two months from the most
violent fever. The legislative authority at last interfered, and prohibited
those dangerous experiments-}-.

* See APPENDIX, Note B B.

•t M. M. Prevost and Dumas have recently made some very interesting experiments
on the blood, by which they have shown the different sizes and figures of the globule^
in various animals, as well as the effects produced by transfusion.

According to their observations the diameters of the red globules are,

In man ; the dog ; rabbit ; pig ; hedgehog ; guinea pig ; muscarden -

3750
of an (English) inch 1

Iu the ass ... .......... 4175

1

Cat ; gray mouse ; white mouse . - * - - - - - 4275

Sheep ; horse ; mule ; ox - - ........ 5000

Chamois; stag

She Goat ............. .7200

In figure, the globules are all spherical in the mammalia. In birds they are elliptical,
and vary only in the length of their greater axes. In all cold-blooded animals they are
also elliptical. They found the colourless globule existing in the centre of the particles

of blood has always the diameter of 7500^ in all animals and whatever be the form of the
globule containing it.

209

The experiments on the subject of the transfusion of blood were repeat-
ed, but without success, at the Academy of Sciences. Perault oppos d
this new method, and showed that it was very difficult for one animal to
exist on the blood of another, that this fluid, though apparently the same
in animals of the same age, was as different from it as the features of their
face, their temper, See. that an extraneous fluid was thus introduced, which
conveying to the organs an irritation to which they were not accustomed,
must disorder their action, in various ways 5 that if, as an objection to
what he had said, they should bring forward what takes place in graft-
ing, in which the sap of one tree nourishes another of a different kind, he
would answer, that vegetation does not depend on so complicated, nor on
so delicate a mechanism, as the nutrition of animals ; that a hut may be
formed of all kinds of stones taken at random ; but that to build a palace,
stones must be designedly shaped for the purpose, so that a stone destined
for an arch-, will not do for a wall, nor even for another arch*.

It would be easy, by means of a curved tube, to transfuse the arterial
blood of an animal, from a wound in its carotid artery, into the saphena
vein of a man, into the internal jugular, .or into some of the cutaneous
veins of the fore arm ; but it is to be presumed from experiments on
living animals, that it would be very difficult to transfuse blood into the.
•arteries, as these vessels, filled with blood, during life, do not yield to a
greater distention. The capillaries, in which the arteries terminate, be-
come corrugated, and refuse to transmit a fluid which does riot act upon
them, according to their wonted sensibility. Such was the result of the
experiments of Professor Buniva: he observed, in a living calf, that the
vessels did not transmit freely the fluid which was forced into them, till
the instant when the animal was killed, by dividing the upper part of the
spinal marrow. Attempts have been made to turn to useful purposes
these experiments on transfusing, by limiting the process to the injecting
of medicinal substances into the veins. It is singular, that the moment a
fluid is injected into the veins of an animal, it endeavours to perform mo-
tions of deglutition, as if the substance had been taken in at the mouth.
All these attempts have been too few in number, and are not sufficiently-
authenticated to justify their application to the human subject. But
there is every reason to believe, that, even with the utmost care, the life
of those who should submit to them, would be endangered : so that it is
at once humane and prudent to abstain from themf.

Animals bled till they fainted, died if left alone, or when water or serum of blood (at
100 Fahr.) was injected into their veins If on the contrary blood from an animal of the
same species was injected, every portion of blood thrown in re-animated the exhausted
animal. When it had received as much as it had lost, it breathed freely, took food, and
regained its health. When the injected blood was from an animal of different species,
but having1 globules of the same form, the relief was merely partial, and the animal
could seldom be kept alive for more than six days, diminishing in temperature ^yith
remarkable rapidity. Birds die in most violent nervous affections, as if acted on by viru-
lent poison, when blood having spherical globules is injected. This consequence is
seen even where the quantity of blood lost is small. In very many cases, ca» and rab-
bits were restored for some days by injecting the blood of cows or sheep/ even when
the injection was not made till twelve or twenty -four hours from the extraction of the
blood from the latter. The blood was kept in a fluid state in a cool place, either
by taking away a certain quantity of fibrine or adding 1000th part of caustic soda.
When sheep's blood was injected into the veins of ducks, they died after rapid and

strong convulsions See Bibliotheque Universelle ; Journal de Physique, Sept. 1821.

Phil. Med. Jour. p. 193. vol. v. — Godman.

* Academic Royale des Sciences, 1667, page 37.

t See APPENDIX, Note B B.

2iO

XCIV. Of the secretions.' It has been said, in too general a way, that
the organs receive from the blood conveyed to them by the arteries, the
materials of'the fluids which they separate from it. We have seen, that
the liver is a remarkable exception to this general rule; the same obser-
vation seems, likewise, applicable to the mammae ; they appear to receive
the elements of their milky secretion, from the lymphatics, which are so
very numerous in their structure *.

One is, therefore, justified in saying, .that the elements of our fluids
may be furnished by vessels of every kind, to the organs in which such
fluids may be elaborated. The term secretion, whatever its etymology
may be, denotes that function by which an organ separates from the blood,
the materials of a substance which does not exist in that fluid, with its
characteristic qualities. By the term secretion, one should not, there-
fore, understand the mere separation of a fluid existing, before the action
of the organ by which it is preparedf.

XCV. The difference between the secreted fluids, are evidently con-
nected with those of the organs employed in their formation. Thus, the
arterial exhalation which takes, place, throughout the whole extent of the
internal surfaces, maintains their contiguity, throws out an albuminous
serosity, which is merely the serum of the blood, slightly changed, by
the feeble action of a very simple organization. The analysis of the-
fluid of dropsy, which is merely the serosity constantly transuding from
the surface of the serous membranes, as the pleura and peritoneum,
shows, that it bears the strongest resemblance to the serum of the blood,
and that it differs from it only in the varying proportions of albumen and
of the different salts which it holds in solution.

This first kind of secretion, this perspiratory transudation, would seem
to be a mere filtration, through the pores of the arteries, of a fluid already
formed in the blood. There is, however, besides, an inherent action in
the membranes whose surface it continually lubricates. If it were not for
this action, the serum would remain united to the other constituent parts
of the fluid, which is in too much motion, and at too high a temperature,
to allow of a spontaneous separation. The term exhalation, which is
applied to this secretion, gives an incorrect idea of it, for, exhalation,
which is a purely physical phenomenon, and requiring the presence of
air to dissolve the fluid that is exhaling, cannot take place from surfaces
that are in absolute contact, and between which there is no interval. The
character of this mode of secretion, is the absence of any intermediate
substance, between the vasa afferentia and the excretory ducts; the mi-
nute arteries and veins which enter into the structure of the membranes
being, at once, vasa afferentia and excretory ducts. The fluid secreted
by the serous membranes, though bearing a considerable analogy to the
serum of the blood, differs from it, however, by being animalizecl in a
greater degree. The most important function of these organs is, there-
fore, tt\at they concur in the common process of assimilation ; the office
which has long been assigned to them of fascilitating the motion of the
organs which they envelope, by lubricating their surface, will appear to

* This opinion respecting1 the source of the secretion of milk, is now relinquished by
M. Tlichciand. — Copland.

f Either the material <^ the fluid or the elements necessary to its constitution MUST
exist, before it can be separtued.—- See Phil. Med. Jour. No. 5.—Godman.

211

be of very secondary importance, if it be considered, that respiration
is not impeded by adhesions between the lungs and the pleura, and that,
besides, the brain, which, when the cranium is" whole, is completely mo-
tionless, is entirely surrounded by a serous membrane.

XCVI. Next in order to the serous transudation, which requires a very
simple organization, comes the secretion which takes place in the cryptse,
in the glandular follicles, and in the mucous lacunae* Each of these
small glands, contained within the membranes lining the digestive canal,
air tubes, and the urinary passages, and the collection of which forms the
amygdalae, the arytenoicl glands, Sec. may be compared to a small bottle
with a round bottom, and a very short neck; the membranous parietes
of these vesicular cryptae receive a considerable number of vessels and
nerves. The peculiar action of the parietes of these different parts, de-
termines the secretion of the mucus furnished by those glands. These
mucous fluids, less liquid and more viscid than the serosity which is the
product of the first mode of secretion, contain more albumen and a great-
er number of salts, differ still more from the serum of the blood, are
more animalized, and are of a* more excrem'entitious nature.

The bottom of these ulricular glandulse, is turned towards the parts to
which the mucous membranes adhere ; their mouth, or neck, opens on
the surface at which those membranes are in contact. These kinds of
excretory ducts, wider, or narrower, and always very short, sometimes
unite, run into each other, and open within the cavities. These common
orifices, at which several mucous glands empty themselves, are easily-
seen on the amygdalae, towards the mucous lacunae of the rectum and of
the urethra, at the base of the tongue, 8cc. The albuminous fluid, which
is poured within those glandular cryptae, remains some time within the
cavity, becomes thicker from the absorption of its more fluid parts ; for,
there are, likewise, lymphatics within the texture of th^r parietes. When
the surfaces, on which they are situated, require to be moistened, this
small pouch contracts, and throws up the fluid with which it is filled.
The secretion and excretion are promoted by the irritation which the
presence of the air, of the aliment, or of the urine occasions, by. the
compression exerted by those substances, and lastly, by the peristaltic
contractions of the muscular planes to which the mucous membranes ad-
here, throughout the whole extent of the digestive tube.

XCVII. Those fluids which differ much from the blood, require for
their secretion, organs of a more complicated nature; such organs are
called conglomerate glands, to distinguish them from the lymphatic glands,
which have been termed conglobate. Those glands constitute the viscera,
and are formed by a number of nerves and vessels of all kinds, arranged
in fasciculi, and united by cellular membrane. A membrane peculiar to
the organs, or supplied by those which line the cavities in which they
are contained, covers their outer part, and insulates them from the neigh-
bouring organs.

The intimate arrangement of the different parts which form the secre-
tory glands, the disposition of the arteries, of the veins and nerves, and
the manner in which the lymphatic and excretory ducts arise from them,
has given rise to endless discussions, and formed the basis of former
physiological theories. What follows may be considered as a correct
abstract of what is known on the subject.

The respective arrangement of the simple elementary tissues which
enter into the structure of the glands, and. which form their proper sub-

Stance, or parenchyma*, is different in each of them ; this explains their
differences, in the double relation of their properties and their uses.—-
The arteries are not as Ruysch thought, immediately continuous with
the excretory ducts, nor are there intermediate glands between those ves-
sels, as Malpighi conceived. It seems more probable that each gland
has its own peculiar cellular or parenchymatous tissue, in the areolse of
which, the*arteries pour the materials of the fluid which the gland pre-
pares, in virtue of a power which is inherent to it, and which is its distin-
guishing character. The lymphatics and the excretory ducts arise from
the parietes of those cells; and these two kinds of vessels absorb; the
one set, the secreted fluid which they carry to the reservoirs in which
it accumulates, while the other set take up that part of the fluid, on which
the organ has not completed its action $ in other words, the residue of
secretion.

XCVIII. Of accidental secretions. If one wished to extend the idea
attached to the term secretion, one might say, that every thing, in the
living economy is performed by means of the secretions. What is di-
gestion, but the separation o'r secretion of the chylous or nutritive parts of
aliments, from their faecal or excrementitious portion? Do not the absor-
bents concur in this secretion ; may they not be considered as the excre-
tory ducts of the digestive organs which acts on the aliment, in the same
manner as a secretory gland acts on the blood that contains the materials
of the fluid to be elaborated ? Respiration, as we have already seen, is but
a double secretion which the lungs perform, on the one hand, of the oxy-
gen contained in the atmospherical air, and on the other hand, of the hy-
drogen and carbon, of the water, and of the other heterogeneous principles
contained in venous blood; and, as will be shown in the ensuing chapter,
nutrition is but a peculiar mode of secretion which is different in every or-
gan. It is, therefore, only a series of very delicate and very complicated
separations and analysis, that the organs are enabled to make extraneous
substances undergo such a change of composition, as to render them fit
for their grow Hi and reparation.

There is every reason to believe, that the phenomena of sensation and
of motion, by means of which man keeps up, with surrounding objects,
the relations necessary to his existence, are the result of the secretions
of which the blood furnishes the materials prepared by the brain, by
the nerves, by the muscles, Sec. A plant separates from the earth, in
which its roots are buried, the juices which it requires; these juices
constitute the sap, which, after being filtered through a multitude of ca-
nals, supplies the different secretions, whose products are leaves, blos-
soms, and fruits, with gums, essential oils, and acids. All organized bo-
dies, are, therefore, so many laboratories, in which numerous instruments
spontaneously perform various compositions, decompositions, syntheses^

* Do the different appearances of the substance of glandular bodies depend on the
different manner in which the similar parts cross each other, and on the different pro-
portions in every gland ; or do these differences of colour, of density, by means of which
we so readily distinguish the substance of the liver from that of the salivary glands*
depend on the existence of a peculiar tissue in each organ ,? This question cannot be
answered, in the present state of anatomy. The opinion, however, which suppose^
the different nature of the glands to depend on the the different proportions of those>
constitutent parts, in each of them appears the most probable. — Author's Note

analyses, which may be considered as so many secretions from the com-
mon fluid.

If we confine ourselves in our view of the subject, and limit our atten-
tion to man, the principal and almost the sole object of our study, we
shall see that the different secretions that may take place in him, are
extremely numerous and varied, and that a change in the condition of
one of his organs, is sufficient to enable it to secrete a new fluid. Hence
inflammation in any gland, is sufficient to alter the secretion of the organ
that is affected. A portion of adipose tissue, on being affected with in-
flammation, shall secrete, instead of fat, a whitish fluid known by the
name of pus. The pituitary membrane, when inflamed, furnishes a mu-
cas more fluid and more abundant, and which, by degrees, returns to
its natural state, in proportion as the coryza goes off; the serous mem-
branes, as the pleura and the peritoneum, will allow a greater quantity
of serum of a more albuminous quality, sometimes even coagulable
lymph, to exude 5 at other times, inflammation causes an adhesion of
their contiguous surfaces, and as the inflammatory state varies in intensity,
the accidential secretion will likewise vary as to its qualities ; thus, the
phlegmonous inflammation which should furnish, on terminating in sup-
puration, a whitish fluid, thick, consistent, and almost without smell, will
give out, if the process is not sufficiently active, a serous pu ^colourless,
and without consistence, &c. For the same reason, the blood-vessels
of the uterus pour out in some women, a dark coloured blood while in
others, they give out a mere serosity, very slightly, if at all tinged with
blood*.

The menstrual discharge, in women, is the product of a real secretion of
the arterial capilliaries of the uterus, in the same manner as those vessels
in the pituitary membrane, the membrane which lines the bronchiae, the sto-
mach, the intestines, the bladder, Sec. pour out blood abundantly, or allow
its transudation, when irritation is determined to those parts; in hemor-
rhage from the nose, in bleeding from the lungs, or from the stomach,
when the vessels are not ruptured by external violence. Apoplexy itself,
whether sanguineous or serous, may in several instances, be ranked among
those secretory evacuations, the quality of which varies, according to the
energy of the capillaries which produce it. On opening dead bodies, one
frequently meets with a collection of blood in the ventricles of the brain,
in persons who have died from apoplexy, yet the most careful examination
does not enable one to detect the slightest laceration or rupture in the
veins, or in the arteries within the skullf.

* To these examples of morbid secretions, others majs be added, even more remark-
able, as the vims in rabies canina, in syphilis, the small pox, &c. By some animals the
power is possessed of secreting naturally the most virulent poisons. Of this descrip-
tion are many of the reptiles, but especially the viper, the rattle-snake, &c. There are
others again, which are distinguished by secretions peculiar to themselves. For in-
stance, the ant pours out a fluid of a specific nature, the cuttle fish a dark liquor, and
the skunk a fluid so offensive as to become a means of protection, repelling by its stench
many an assailant. — Chapman.

f That the menstrual discharge results from a secretory action of the uterus, is a doc-
trine which we early adopted, and have taught in our lectures for the last ten years.
Every other hypothesis on the subject is totally irreconcileable with facts, and repug-
nant to the laws of the animal economy. The crude speculations of former times, re-
specting this operation, may, indeed, be considered as discarded. Does any one, for in-
tance, whose knowledge has kept pace with the improvements of physiology, now en-

The nerves, of which there is always a certain number in the structure
of the secretory organs, and which are principally branches of the great
sympathetic* nerves, terminating- in various ways, in their substance, give

tertain the notion of lunar influence, of fermentat on, of venereal appetite, of general
plethora or local congestion, &c. &c. ? The leading arguments, in defence of this doc-
trine, nui.) be thus enumerated.

1. *lha\ the uterus, in its villous and vascular structure, resembles a gland, and also
in iis diseases, being equally liable to scirrhus, cancer, &c. &c.

2. That, like otiier secretory organs, blood is very copiously diffused through it.

3. That, by the arrangement of its vessels, it is evidently designed that the circula-
tion should oe retarded for the purpose of secretion. The arteries are not only exceed-
ingly convoluted, but tney are larger, and with thinner coats than their corresponding
veins.

4. That, in common with other secretions, menstruation is often, at first, imperfectly
performed, and is subject afterwards to vitiation and derangement. In the beginning
the discharge is commonly thin, colourless, and deficient, and recurs at protracted and
irregular intervals. In some of the particulars, it is analogous to these seminal secre-
tion.

5. That, in many of the inferior animal^ during the season of venereal incalescence,
there is an uterine effusion which is undoubtedly a secretion. This answers, seemingly,
the same end as menstruation, namely, giving to the uterus an aptitude for conception. —
Though this fluid generally differs from the menses in complexion, yet in some instan-
ces, they are precisely similar. Whenever the veneral desire suffers a violent exacer-
bation from restraint or other causes, the discharges in these animals become red. This
has been more especially remarked in bitches kept from the male.

6. That, when the menses are suppressed, they cannot be restored by inducing ple-
thora, noi the flow bo checked by blood-letting, or any other means of depletion. Be-
sides, no vicarious discharge relieves the symptoms of suppression. Do not these facts
very unequivocally proclaim the existence of a secretory function ?

Lastly, That the menses are a fluid sui generis, or at least varying essentially from
blood ; having neither its colour, nor odour, nor coagulability, and, on chemical analysis,
present different results. Let us ask, if the menstrual fluid be not blood, what is it ?
To the objection, which has sometimes been urged, that the uterus is not sufficiently
glandular for the office alleged, it may be, I think, very satisfactorily replied, that there
is hardlv a viscus or surface of the body, which is not competent to this purpose. It
would really seem that no operation of the animal economy requires a less complex ap-
paratus. Of what, indeed, dors- a gland consist, except a congeries of vessels i1 Even
the most perfect of the secretions are accomplished by this simple contrivance. If a
few vessels, " creeping through the coax's of the stomach," can secrete the gastric
liquor, why may not the infinitely more glandular organization of the uterus elaborate
the menstrual fluid ? As yet we know of no glandular structure in vegetables, they con-
taining only tubes or vessels, through which the fluids circulate. Notwithstanding,
however, the want of glands, we find the sap of plants converted into oil, mucilage,
acids, &c. No stronger proof can certainly be required of the extreme simplicity of
the organs by which the secretory transformations are effected.

Who originally suggested the theory of secretion we have not been able to ascertain.
Ithasvery^enerally been'ascribedto the celebrated Mr. Hunter; but the evidence of
his claims to it is exceedingly slender. The only trace of it, which we can discover m
his writings, is a vague expression in a paragraph of his Treatise on the Blood. Atter-
wards, however, he furnished an extract from his lectures to be published in Johnson s
Midwiferv, as exhibiting more fully his notion respecting this function. Speaking of the
death of "the blood from lightening, and other sudden causes, he includes the catamenia
amonq; the illustrations of his reasonings. " The blood (says he) discharged in men-
struation is neither similar to blood taken from a vein of the same person, nor to that
extravasated by an accident in any other part of the body; but is a species of blood
clv*ne;ed separated, or thrown off from the common mass by an action of the vessels ot
the uterus, in a process similar to secretion, by which action the blood, having lost its hv-
int? principle, does not coagulate," &c.

"The blood (says Holler) is brought into the womb in greater quantity, and more
quickly, through its lax and ample arteries, and on account of the rigidity and narrow-
ness of the veins it returns with difficulty.— Chapman.

* They are likewise given off, in great numbers, from the cerebral nerves : thus, the

215

to each of them a peculiar sensibility, by means of which they discover in
the blood which the vessels bring to them, the materials of the fluid which
they are destined to secrete, and these they appropriate to themselves by a
real selection. Besides, the nerves communicate to them a peculiar mode
of activity, the exercise of which makes those separated elements undergo
a peculiar com position, and bestows on the fluid which is the product of it,
specific qualties always bearing a certain relation to the mode of action of
which it is the result. Thus, the liver seizes the materials of the bile con-
tained in the blood of the vena portae, elaborates, combines those materials,
and converts them into bile, an animal fluid, distinguishable by peculiar cha-
racteristic properties, subject to certain variations, according as the blood
contains in different proportions, the elements of which it is formed; ac-
cording as the gland is more or less disposed to retain them, and to blend
them together. The qualities of the bile depending on a concurrence of
all these circumstances, must present as many differences as the blood which
contains its elements, and the liver may present varieties, with regard to
the composition of the former, and to the activity of the latter. Hence
the many changes in the qualities of the fluid, the slightest of which, not
affecting the health, escape observation, while those changes which are
greater, and which disorder the natural order of the functions, show them-
selves in diseases of which they maybe considered as the effect and at other
times, as the cause. These changes in the condition of the bile (and what is
now said applies to almost all the secretions of the animal economy), these
changes are never carried so far as to make the bile lose all its distinguish-
ing characters, it never takes on the qualities belonging to another fluid,
it never resembles semen, urine, or saliva.

The secretory glands do not carry on an uninterrupted action ; almost all
of them are subject to alternate action and repose: all as Bordeu observed,
sleep or waken, when irritation affects them, or their neighbouring parts,
and determines their immediate and sympathetic action. Thus, the saliva
is more plentifully secreted during mastication ; the gastric juice is poured
within the stomach, only while digestion is going on ; when the stomach
is emptied of food, the secretion ceases, and is renewed^ when the pre-
sence of food again excites a sufficient degree of irritation*. The bile
flows more abundantly, and the gall bladder frees itself of that which it
contains, while the duodenum is filled by the chymous mass.

When a secretory organ is in action, it determines the motion of the
parts in its vicinity, or, as Bordeu expresses it, within its atmosphere.
A part is said to belong to the department of a certain gland, when it par-
takes in the motion affecting the latter, during the process of secretion,
or when it is employed in functions subservient lo that of the gland ;
these departments are of different extent, according to the importance of
the action of the gland. Thus, one may say that the spleen and most of
the viscera of the abdomen are of the department of the liver, since they

salivary glands receive from the seventh paii> from the maxillary nerve from the fifth
pair, and from the cervical nerves, a number of nerves that will "appear very great, if
the bulk of those glands is considered — Author's J\ote.

* This is very contrary to the observations of Wilson Philip, whose experiments show,
that the secretion of the gastric fluid precedes the reception of food, and may be es-
teemed the immediate cause of the sensation ot'bunger. According1 to him, the secre-
tion is suspended, as soon as the stomach receives a certain quantity of food. See his
Treatise on Pevers, appendix to Vol. 2. and ius Inquiries on Indigestion.— Godman,

receive from it, the biood ou which they are to act. The liver is also-
comprised in the sphere of activity of the duodenum, since the distension
of that intestine irritates it, determines a more copious flow of its fluids,
and a more abudant secretion of bile.

C. The blood which is sent to a secretory gland, before reaching it, un-
dergoes preparatory changes, which dispose it to furnish the materials of
the fluid which is to be separated from it. We have seen, in treating of
digestion, how the blood which the vena portae sends to the liver, is fit
for the secretion of bile. There can be no doubt, that the portion of
blood which it carries to the testicles, by the long, slender, and tortuous
spermatic arteries, undergoes changes*, which bring it nearer to the se-
minal fluid.

The rapidity with which the blood flows into an organ, the length, the
diameter, the direction, the angles of its vessels, the arrangement of their
extreme ramifications, which may be stellated, as in the liver, in fasciculi,
as in the spleen, convoluted, as in the testicles, Sec. are circumstances
which should be taken into account in the study of each secretion, since
all have some influence on the nature of the fluid secreted, and on the
manner in which the secretion is effected.

The fluid which lubricates the whole extent of the moveable surfaces
by which the bones of the skeleton are articulated together, is not exclu-
sively prepared by the membranous capsules which envelope the articu-
lations. A number of reddish coloured cellular substances, placed in
their vicinity, co-operate in the secretion. Though these parts, which
were long considered as synovial glands, do not completely resemble the
conglomerate glands, and although no glandular bodies, nor excretory
ducts, can be demonstrated in them, they cannot, however, but be consi-
dered as fulfilling, to a certain degree, the same functions, and one must
admit that they are of some utility, in the secretion of the synovia. They
are always met with; their extent and bulk are always proportioned to
the extent of the auricular .surfaces, and to the frequency of motion in
the joints near which they are situated. They are found in all animals ;
pale and light coloured in those which have been long at rest; red, high-
ly vascular, and bearing the marks of a kind of inflammatory diathesis,
in those which have been compelled to violent exercise, as the oxen which
are brought to Paris from distant provinces, and the wild animals which
have been hunted. In anchylosis, they are less red and of greater con-
sistence, than in a healthy state.

When, from the irritation attending friction, the fluids are determined
towards an articulation which is in motion, do they not then, by passing
through those glandulo-cellular bodies, undergo a peculiar modification
which renders them fitter for the secretion of synovia. This would not
be the only instance, in the human body, of parts whose action is but se-
condary and connected with that of other organs principally engaged in a
secretion whose materials are contained in the blood which passes through
them. It will be urged, no doubt, that this preparatory apparatus is not
met with in the neighborhood of the great cavities , but it should be re-

* By this loose expression one might be induced to suppose that the changes here al-
luded to were spontaneous, or chemical. It should have been said that the peculiar or-
ganization of the spermatic vessels seems designed to produce the changes which bring
the blood nearer in character to the Seminal fluid. — Godman,

217

collected, that the chemical composition and the uses of the synovia, are
not precisely the same as those of the fluids secreted by the pleura or the
peritoneum ; and that, besides, the analogy between two objects, does
not constitute their identity. The human mind being naturally indolent,
loves to discover analogies that support it in its weakness, and that may
save it the trouble of seeking points of difference. I am aware, that to
prove that the mechanism of the synovial secretion, which exactly resem-
bles that of the fluid which moistens the inside of the great cavities, re-
quires like it but a simple membranous apparatus, it is customary to re-
peat, in every possible way, that Nature is scanty in her means, and la-
vish in her results; that she produces from the same cause, a variety of
different effects, Sec. but without pointing out the manifest absurdity of
admitting metaphysical arguments in the natural sciences, is it not much
more reasonable to acknowledge with philosophers, that the primitive
cause may vary in many ways, and that its innumerable modifications,
whence arise the difference in the effects, exceed the limited powers of
our understanding?

CI. When a gland is irritated, it becomes a centre of fluxion, towards
which the fluids are determined from every part; it swells, hardens, con-
tracts, is in a kind of state of erection, bends on itself, and acts on the
blood conveyed by its vessels. Secretion, depending on the peculiar and
inherent power of the glandular organ, is promoted by the slight motion
which it receives from the neighbouring muscles. The gentle pressure
of those parts on the glandular organ, is sufficient to keep up their excite-
ment, atid to assist in the separation and excretion of the fluid. Bordeu,
in his excellent work on the glands and on their action, has shown that it
is not in consequence of the compression which is produced on them by
the neighbouring muscles, that they part with the fluid they have pre-
pared, that physiologists were therefore very much in the wrong, in say-
ing, that the excretion of a fluid consisted merely in its expression, and
in comparing, under that point of view, the glands to sponges soaked
with a fluid which they give out, on being squeezed.

The excretory ducts of organs absorb or reject the secreted fluid, ac-
cording as it affects their inhalent mouths : these canals partake in the
convulsive state of the gland, undergo a degree of erection, and contract
on the fluid to expel it. Thus, the saliva starts from the parotid duct,
at the sight, or in the recollection of food that has been longed for; thus,
the vesiculae seminales and the urethra (for the reservoirs in which the
fluids lie some time before being expelled, may be considered as forming
apart of the excretory ducts), contract, become straighter, and lengthen
themselves to force to a distance the spermatic fluid.

The thin and transparent ureters in fowls have been seen to contract
on the urine, which, in these animals, concretes on the slightest stagna-
tion.

After remaining a certain length of time, in that state of excitement,
the glands relax, their tissue collapses, the juices cease to be conveyed
to it as plentifully, they fall into a state of repose or sleep, which restores
their sensibility, exhausted by too much action. It is well known, that a
gland over-stimulated, becomes, like any other part, insensible to the
stimulus, the continued appplication of which parches and exhausts it.

From what has just been said relative to the mechanism of the secretions,
it will be seen that this function may be divided into three very distinct pe-
riods ; IstMhat of irritation, characterised on the growth of the vital pro-

2 E

218

perties, and by the more copious accession of the fluids, the necessary
consequence of that excitement; 2nd. the action of the glands; that is,
its secretion, properly so called; 3d. lastly, the action by which the organ
parts with the fluid which it has prepared: this is the last process, it is
called excretion, and is promoted by the action of the neighbouring parts.
The determination of fluids to the part, the secretion and excretion suc-
ceed each other; they are preceded by the excitement, which is the pri-
mary cause of all the subsequent phenomena. The circulation is, at first,
excited, more blood is sent into the part, and penetrates into the tissue of
the gland. Dr. Murat has had occasion to open a considerable number
of old men, who died at the Bicetre, and who were known to be great
smoakers of tobacco. He uniformly observed, that their parotid glands,
continually called into action by that habit, were larger than in those
who were not given to it, and that they were remarkably red, in conse-
quence of the blood with which they were constantly injected.

What is the office of the nerves in the act of secretion? what share has
the nervous influence in the elaboration of the fluids furnished by the
glandular organs? All the glands which receive their nerves from the
system of animal life, such as the lachrymal and salivary glands, appear,
in certain cases, to receive, from the brain, the secretory excitation. The
influence of the imagination is sufficient to determine it; thus, we shed
involuntary tears, when the mind is taken up with painful thoughts; and
the mouth fills with saliva, on the recollection of a grateful meal*. In
such cases, the influence of the nerves on the process of secretion, is in-
disputable: it is not so, however, with the conglomerate glands that re-
ceive their nerves from the great sympathetics. The secretion of the
kidneys, of the liver, and of the pancreas, appears less influenced by affec-
tions of the mind; the brain, besides, has no immediate connexion with
these glands; their nerves are, almost entirely, given off by the great
sympathetics; the kidneys in particular, receive no nerves from the brain,
or from the spinal marrow ; hence the secretion of urine seems, more
than any other, to be independent of the nervous influencef.

* These glands, viz. the lachrymal and salivary, receive nerves both from the nearest
ganglions, and from the nerves of voluntary motion : the former set of nerves mos.t pro-
bably enables them to perform their ordinary functions, the latter excites or reinforces
these functions whenever the mind is under certain impressions.

•f- Although these organs are not directly influenced by the cerebral and spinal nerves,
it cannot be satisfactorily denied that the ganglial nerves, which are so abundantly dis-
tributed to the blood-vessels supplying these organs, bestow on these vessels that pe-
culiar influence which determines the nature and quantity of the secretion ; for how can
we suppose the capillary tubes, through which the blood flows, to be able to secrete a
peculiar fluid of themselves, without resorting to the position that the nerves, which so
abundantly supply the ramifications of the blood-vessels, and the substance of the se-
creting organs, actually influence, and, through the medium of those vessels, even
produce the secretions in question ? Are not these nerves requisite to the vital actions
of the viscera which they supply? Do we know an animal that does not possess them
as a most essential part of its organization ? And can we suppose that they are distri-
tributed in so abundant a manner to the vessels of a secreting organ, without perform-
ing a most requisite part in the production of the fluids which that organ secretes ? A
close investigation ot the structure of the secreting viscera and surfaces shows that their
blood-vessels, which bear in their number and size a close relation to the extent of func-
tion which such viscera individually perform, are more amply supplied with this class of
nerves than the vessels of any other of the animal textures : indeed every important se-
creting gland has a distinct g'anglion, or plexus of these nerves surrounding the blood-
vessels which belong to it , but more especially the arteries, and some of these organs

This great number of secretory organs, constantly engaged in separating
various secretions from the mass of the fluids, would soon exhaust it, if
the calculations of physiologists of the amount of what a gland is capable
of secreting, were not manifestly exaggerated. In fact, if w,e admit, with
Haller, that the mucous glands of the intestinal canal secrete, in twenty-
four hours, eight pounds of mucous; that, in the same lapse of time, the
kidneys secrete four pounds of urine,- that the same quantity is lost by the
insensible perspiration; and again, as much by the pulmonary exhalation;
there will be lost, daily, twenty pounds of fluids, almost entirely excre-
mentitious; for we do not include in that calculation the bile, the tears,
nor the saliva and pancreatic fluid, which, in part, returns into the blood
after being separated from it; nor the serum which moistens tl|e internal
surface, and which is purely recrementitious.

This exaggeration, in the calculations of the fluids which ,are daily-
poured out by the different emunctories, is to be attributed to the%:ircum-
stance of having taken the maximum of each secretion, without consider-
ing that they mutually supply each other; so that, when less urine is void-
ed, the quantity of perspiration is greater, and vice versa. It is very
well known, that a violent diarrhea is frequently the consequence of sud-
den cold applied io the skin ; the fluids at once repelled towards the in-
testiual canal, having to pass through the mucous glands whose action is
greatly increased.

CII. It has been customary to enumerate, among the glands, certain
bodies which have truly a glandular appearance; but the uses of which
are yet unknown. Thus, the thyroid and thymus glands, which are pa-
renchymatous organs destitute of excretory ducts, though receiving many
vessels and some nerves, do not appear to secrete any fluid. But may not
the blood, which is conveyed so plentifully to the thyroid gland, undergo
nevertheless certain changes, though we may not be able to discover
what they are? Besides, may not the lymphatics perform the office of
excretory ducts, and convey back again immediately into the mass of the
blood, the fluid which has undergone changes in the glandular body? The
capsulse renales are in the same condition: they have, however, in addi-
tion, an internal reservoir, a kind of lacuna, whose parietes are smeared
with a viscid and brown-coloured substance secreted Ay the capsule, and
which doubtless is conveyed into the mass of the bipod by the lymphatics
arising from the parietes of its internal cavity.

CHI. Of the secretion ofadeps within the cellular tissue. This soft tissue,
which is diffused over the whole body, and a#>rds a covering to all our
organs, is of use not merely in separating ^em from one another, and
connecting together the different parts; it j/ besides, the secretory organ
of the adipose substance, a semi-concrete/oily, animal substance, which
is found, in almost every part of the bo/y, deposited in its innumerable
cells. The membranous parietes of these small cellular cavities are sup-
plied by numerous minute arteries, i/i which the adeps is separated; it is
conveyed by its specific light weight to the circumference of the column
of blood in the vessels, and transudes through the pores in their parietes.
Its quantity and consistence vary, in different parts of the body, and in

have both a large plexus of nerves and a ganglion, whence their nerves are exclusively
derived, arid which appear to be entirely devoted to the functions of the viscus, whose
blood-vessels they plentifully supply. See, on this subject, the APPENDIX, Notes H,
A, A, and those on Digestion, Sac.-*- Copland.

different persons: there is situated below the skin a thick layer of cellu-
lar substance (fatty pannick;') it is found, in considerable quantity, be-
tween the interstices of the muscles, along the blood-vessels, near the
articulations, and in the vicinity of Certain organs, as the eyes, the kid-
neys, and the breasts. That which fills the bottom of the orbit, and
which surrounds the eye-ball, is softish and almost fluid; that which en-
velopes the kidneys and the great joints is, on the contrary, of the con-
sistence of suet. Between these two extremes there are many gradations,
and it may be said, that the animal in question, is not exactly the same
in any two different parts of the body. The high temperature of the hu-
man body maintains it in a state of semi-fluidity, as may be observed in
surgical operations.

In some parts, it is even absolutely fluid, but its nature is then observed
to be greatly changed; it no longer contains any oily substances, and differs
but littte Yrom a mere aqueous gelatine. Thus, the fluid in the cellular
tissue of the eye-lids, of the scrotum, Sec. has been considered by several
physiologists, as absolutely different from fat. It may not be amiss to
observe, that the lamina of the cellular tissue, in such circumstances,
yield more readily to extension, present a greater surface, form mem-
branous expansions^, and circumscribe ceHs~of considerable size, so that
the differences in the secretion, perfectly coincide with the difference of
structure. It may further^oe observed, that the functions of the eye-lids
and of the penis required that they should not contain any fat. Conside-
rable deformity, when the person grew fat, would have been the conse-
quence of the increased bulk of these parts, and besides, the folds of the
skin would not have that free motion which their functions require. No
real adeps is ever found within the skull, and the utility of this condition
is very obvious. To how many dangers would not life have been exposed,
if a fluid so varying in quantity, and the amount of which may be trebled,
in a very short lapse of time, had been deposited into a cavity accurately
filled by an organ which is affected by the slightest compression ?

In an adult male, of moderate corpulence, the proportion of adeps is
about one-twentieth of the weight of the whole body; it is greater, in
proportion, in children and in females ; for, its quantity is always relative
to the energy of the functions of assimilation. When digestion and ab-
sorption are performed with great activity, fat accumulates within the
cellular substance: atd if it be considered that it is but imperfectly ani-
malized, that it bears ttie most striking analogy to the oils extracted from
plants; that it contains \«ry little azote, and much hydrogen and carbon,
like all other oily substances, since on distillation it is decomposed, and
yields water and carbonic a*id, with a very small quantity of ammonia;
that its proportions are very variable, and may be considerably increased
or diminished, without manifestly impairing the order of the functions;
that animals that spend a great ^art of their life without eating, seem to
exist during that torpid state, on the fat which they have previously ac-
cumulated in certain parts of their body*; one will be led to think, that

* Marmots and dormice become prodigiously fat during the autumn; they then take
to their holes and live in them during the six winter months, on the fat which is accu-
mulated in all their organs. There is most fat collected in the abdomen, in which the
epiploon forms masses of a considerable size. When, in the spring, their torpor ceases,
and they awaken from their sleep, they are for the most part, exceedingly emaciated. —
Author's Note,

221

the state of fat is, to a portion of the nutritive matter extracted from the
food, a kind of intermediate state, through which it has to pass before it
can be assimilated to the animal whose waste it is destined to repair.
Animals which live on grain and vegetables, are always fatter than those
•which live exclusively on flesh. Their fat is consistent and firm, while
that of carnivorous animals is almost completely fluid.

A corpulent man, on having his diet suddenly reduced, sensibly be-
comes thinner, in a very short time: the bulk and weight of his body
diminish, from the absorption of the fat which supplies the deficient
quantity of blood. Adeps may, therefore, be considered as a substance
in reserve, by means of which, notwithstanding the small quantity of food
and its want of nutritious qualities, Nature finds wherewith to repair the
daily waste.

CIV. The use of adeps is not, as has been stated, on the authority of
Macquer, to absorb the acids that are formed in the animal economy;
that which is obtained from it, by distillation, (the sebaceous add] is anew
product formed by the combination of the atmosphere with the hydro-
gen, the carbon, and the small quantity of azote which it contains. The
small quantity of this last substance nearly constitutes it a vegetable
acid. Fat has a considerable affinity for oxygen, and by combining with
it, turns rancid, after remaining some time exposed to the air. It de-
prives metallic oxides of a part of their oxygen, and likewise, on being
triturated with metallic substances, promotes their oxidizement. In pro-
portion as it absorbs oxygen, its density increases : thus oils become
concrete by combining with oxygei, and fat acquires a consistence almost
equal to that of wax, which is itself a fatty substance highly oxidized.

Besides the principal use which we have assigned to adeps, and ac-
cording to which the cellular system may be looked upon as a vast reser-
voir, in which there is deposited a considerable quantity of nutritive and
semi-animalized matter, this fluid answers several purposes of secondary
^utility. It preserves the body in i;s natural temperature, being, as well
as the tissue of the cells in which it is contained, a very bad conductor of
heat. Persons who are excessively corpulent, scarcely feel the most
severe cold; animals which inhabit northern climates, besides being
clothed in a thick fur, are likewise provided with a considerable quantity
of fat. The fishes of the frozen seas, the cetaceous animals which sel-
dom go far from the polar regions, all kinds of whales are covered with
fat, and have likewise a considerable quantity within their bodies. By
its unctuous qualities, fat promotes muscular contraction, the motion of
the different organs, the free motion on each other of the different sur-
faces; it stretches and supports the skin, fills vacuities, and gives to our
limbs those rounded outlines, those elegant and graceful forms peculiar
to the female body. Lastly, it envelopes and covers over the extremities
of the nerves, diminishes their susceptibility, which is always in an in-
verse ratio of the corpulency ; which induced a physician of merit to say,
that the nervous tree, planted in the. adipose and cellular substance, suf-
fers, when from the collapse and the removal of that tissue, its branches
are exposed, in an unprotected state, to the action of external causes, as
injurious to them as the rays of the sun to a plant torn from its native
soil. It is, in fact, observed that nervous people are exceedingly thin,
and have an excessive degree of sensibility. Too much fat, however, is
as injurious as too small a quantity of it. I have seen several persons
whose obesity was such, that besides being completely incapable of

£22

taking the slightest exercise, they were in great danger of suffocation,
Respiration in such persons is at times interrupted by deep sighs, and
their heart, probably overloaded with fat, expels with difficulty the blood
within its cavities.

CV. According to modern chemists, the use of fat is to take from the
system a part of its hydrogen. When the lungs or liver are diseased,
when respiration or the biliary secretion do not carry out of the system,
a sufficient quantity of that oily and inflammable principle, fat forms in
a greater proportion. They appeal to the result of the experiment of
shutting up a goose, whose liver is to be fattened, in a confined cage,
placed in a hot and dark situation, and in gorging it with paste, of which
it eats the more greedily, as being unable to stir, it gratifies its inclina-
tion to action, by exerting the organs of digestion. Notwithstanding
this quantity of food, the bird becomes emaciated, is affected with a kind
of marasmus, its liver softens, grows fatter, more oily, and attains an
enormous size.

This experiment, and many other facts, prove, that the secretions from
which analogous products are formed, may mutually supply each other ;
but can we admit the chemical theory bf the use of 1'at when we recollect
that frequently, in the most corpulent persons, respiration and the secre-
tion of bile are performed with great freedom and with no difficulty;
while the difficult respiration attending pulmonary consumption, and the
difficult flow of the bile from an obstruction of the liver, are always ac-
companied with complete marasmus.

Whatever moderates the activity
bring on adipose plethora. Thus an i
profuse bleedings, castration, sometir
•which the cellular tissue appears affe
actual adipose infiltration, which ma)
rise to tumours called steatomatous.

the circulatory system, tends to
active state of the mind and body,
es induce obesity, an affection in
ed with atony, and undergoes an
be compared to that which gives
f the energy of the heart and arte-

ries is too great, emaciation is always the consequence; when, on the con-
trary, the sanguineous system is languid, there is formed a merely gela-
tinous fat, and the corpulence is a mere state of bloatedness.

This incompletely formed fluid, wl^ch distends the parts in persons of
a leucophlegmatic habit, is but an ifnperfect kind of fat; it resembles
the marrow or the medullary juice which is merely a very liquid fat,
whose consistence diminishes when animals become lean. Inclosed with-
in the cells of the osseous tissue, in cavities whose sides cannot collapse,
and whose dimensions must always remain the same, the marrow of which
they are never free, is of different degrees of density; and what authors
say of its diminished quantity, must be understood as applying to the di-
minution of its consistence.

CVI. The secretion of the marrow is, like that of the fat, a mere arte-
rial transudation ; it is performed fyy the medullary membrane, which is
thin, transparent, and cellular, which lines the inside of the central cavity
of the long bones, and extends over all the cells of their spongy substance.
The medullary membrane, when^n a healthy state, does not give any
marks of relative sensibility. In all the amputations I have performed,
and they have not been few: in all the operations of the same kind at
which I have been present, whatever the bone was, whether it was divi-
ded near a joint or in the middle of its body. I never knew the patient
complain of pain, provided the limb was well supported by the assistants,
and provided no jerk was given by the operator himself. In that opera-

223

tion, the pain occasioned by the division of the skin and of the nerves,
overcomes every other pain, and I have always seen patients impressed
with the popular prejudice, and expecting anxiously the division of the
bone, feel quite free from pain, as soon as the saw had begun to work.
Nay, several, after expressing, by their cries, the most acute pain, taking
advantage of the kind of ease which follows the division of the flesh, raise
their head, and look on, while the bone is being sawn through ; at once
actors and spectators in this last part of a painful and bloody operation.

Yet the medullary membrane, the injury of which is attended with no
pain, while in a hea'lthy state, becomes the seat of the most exquisite sen-
sibility in the pains in the bones, which mark the last stages of the
venereal disease; in the kind of conversion into flesh, of the solid bone^
known by the name of spina ventosa. as will be mentioned, in speaking
of the uses of the marrow, in the chapter on the organs of motion and
on theii* action.

CHAPTER VI.

OF NUTRITION.

CVII. ALL the functions which we have hitherto made the object of
our study; digestion, by which the alimentary substances received with-
in the body, are deprived of their nutritive parts; absorption, which con-
veys that recrementitious extract into the mass of the fluids : the circu-
lation, by which it is carried to the parts wherein it is to undergo different
changes; digestion, circulation, absorption, respiration, and the secre-
tions, are but preliminary acts, preparatory to the more essential function
treated of in this chapter, and the consideration of which terminates the
history of the phenomena of assimilation.

Nutrition may be considered as the complement of the functions of as-
similation. The aliment, altered in its qualities, by a series of decom-
positions, animalized and rendered similar to the substance of the being
which it is to nourish, is applied to the organs whose waste it is to
repair; and this indentification of the nutritive matter to our organs
which take it up and appropriate it to themselves, constitutes nutrition.
Thus, there is accomplished a real conversion of the aliment into our
own substance.

There is incessantly going on a waste of the integrant particles of the
living body, which a multiplicity of circumstances tend to carry away
from it; several of its organs are constantly engaged in separating from
it the fluids containing the recrementitious materials of its substance
worn by the combined action of the air and of caloric, by inward friction,
and by a pulsatory motion that detaches its particles.

Alike, therefore, to the vessel of the Argonauts, so often repaired in
the course of a long and perilous navigation, that on her return, no part
of her former materials remained: an animal is incessantly undergoing

decay, and if examined at two different periods of its duration, does not
contain one of the same molecules. The experiment performed with
madder, which dyes red the bones of animals among whose food it is
mixed, proves, most unquestionably, this incessant decomposition of ani-
mated and living matter. One has only to interrupt, for a sufficient
length of time, the use of that plant, to make the uniformly red colour
assumed by. the bones completely disappear. Now, if the hardest and
most solid parts, most calculated to resist decay, are undergoing a per-
petual motion of decomposition and of regeneration ; there can be no
doubt, that this motion must be far more rapid in those whose power of
cohesion is much inferior; for example, in the fluids.

Attempts have been made to determine the period a.t which the body is
completely renovated; it has been said, that an interval of seven years
\vas required for one set of molecules to disappear and be replaced by
others; but this change mj^st go on more rapidly in childhoofl and in
youth. It must be slower at a mature age, and must require a consider-
able time, at a very advanced period of life, when all the parts of the body
become, in a remarkable degree, fixed and firm in their consistence while
the vital powers become more languid. There can be no donbt, that the
sex, the habit, the climate in which we live, the profession we follow, our
mode of life, and a variety of other circumstances, accelerate or retard
it; so that it is absolutely impossible to fix, with any degree of certainty,
its absolute duration.

CVIII The parts of our body, in proportion as they undergo decay,
are repaired only by means of homogeneous particles exactly like them-
selves : were it otherwise, their nature, which always remains the same,
would be undergoing perpetual changes.

When, in consequence of the successive changes which it has undergone
from the action of the organs of digestion, of absorption, of the circu-
lation, of respiration, and of secretion, the nutritive matter is animalized
or assimilated to the body, which it is to nourish, the parts which it
moistens, retain it and incorporate it to their own substance. This nu-
tritive identification is not performed alike in the brain, in the muscles,
in the bones, &c. Each of them appropriates to itself, by a real process
of secretion, whatever it meets with fitted for its nature, in the fluids con-
veyed to it by the different kinds of vessels, but especially by the arteries,
it leaves unaffected, the remaining heterogeneous particles. A bone is
a secretory organ, around which the phosphate of lime is deposited ; the
lymphatic vessels which, in the process of nutrition, perform the office
of excretory ducts, remove that saline substance, when it has lain suffi-
ciently long in the cells of its tissue. The same happens to the muscles,
•with regard to fibrina, and to albumen with regard to the brain ; every
part appropriates to itself, and converts into a solid form, those fluids
\vhich are of the same nature, in virtue of a power of which the term af-
finity of aggregation, used in chemistry, gives an idea, and of which it is
perhaps the emblem.

The nutrition of a part requires that it should be possessed of sensibi-
lity and motion ; by tying the arteries and nerves of a part, it cannot be
nourished, nor can it live. The blood which flows along the veins, the
fluid conveyed by the absorbents, contain, in a smaller proportion than
arterial blood, vivifying the reparatory particles. It is even commonly
thought, that the lymph and venous blood contain no directly nutritive
particles. As to the share which the nerves take in the process of mi-

225

trition, that is not yet completely determined. A limb that is para-
lized, by the division or tying of its nerves, or by any other affection, some-
times retains its original size and plumpness ; most frequently, however,
though perhaps for want of motion, it becomes parched, emaciated, and
skrinks in a remarkable degree.

CIX. We should be enabled to understand the process of nutrition, if
after having accurately determined the difference of composition between
our food, and the substance itself of our organs, we could see how each
function robs the aliments of their qualities, to assimilate them to our
own bodies; and what share each function takes in the transmutation of
the nutritive particles into our own substance. To illustrate this point,
suppose a man to live exclusively on vegetable substances, which, in fact,
form the basis of our food ; on whatever part of the plant he may live,
whether on the stem, on the leaves, on the blossoms, on the seeds, or on
the root; carbon, hydrogen, and oxygen enter into the composition of
these vegetable substances, which, by a complete analysis, may all be
resolved into water and carbonic acid. To these three constituent prin-
ciples, there is frequently united a small quantity of azote, of salts, and
of other materials, in different proportions. If then, we examine the na-
ture of the organs in this man whose food is entirely vegetable, it will be
found that they are different in their composition, and t'ar more animal-
ized than that kind of food; that azote predominates, though the vegeta-
ble substance contains none or only a very small quantity, that new pro-
ducts, undistinguishable in the aliments, exist, in considerable quantity,
in the body which is fed on them, and appear produced by the very act
of nutrition.

The essence of this function is, therefore, to make the nutritive matter
undergo a more advanced state of composition, to deprive it of a portion
of its carbon and of its hydrogen, to make azote predominate, and to
produce several substances, which did not exist in it before. All living
bodies seem to possess the faculty of composing and decomposing the
substances by means of which they are maintained, and to form new pro-
ducts: but they possess it, in various degrees of energy. The sea-weed,
from the ashes of which soda is obtained, on being sown in a box of soil,
in which there is not a single particle of that alkali, and watered with
distilled water, will for a time continue to form it, as if it had grown
on the sea-shore, in the midst of marshes constantly inundated by salt
and brackish water.

Living bodies then, are real laboratories, in which are carried on
combinations and decompositions which art cannot imitate ; bodies that
appear to us simple, as soda and silex, seem to be formed by the union
of their constituent particles: while other bodies, whose composition we do
not understand, undergo an irresistible decomposition : hence, one may
infer, that the power of Nature in the composition and decomposition of
bodies, far exceeds that of chemistry*.

Straw and cereal plants contain an enormous quantity of silex, even
when the earth in which they grow bus been carei'ully deprived of its si-
liceous particles. Oats, particularly, contain a considerable quantity of
that verifiable earth ; the ashes obtained by burning its seed, on being

* To the substances compounded by the animal body may be added lime, which is
formed in quantities far exceeding the amount taken in with the food.— Godman.

2 F

analyzed by means of the nitric acid, were found by M. Vauquelin, to
contain T6^ of pure silex indissoluble in that acid, and 0,393 of phos-
phate of lime dissolved in it.

The excrements of a hen, fed, for ten days, on oats only, on being cal-
cined and analyzed by the same chemist, produced twice as much phos-
phate and carbonate of lime as was contained in the oats, with a small
deficiency in the quantity of silex, which might have been employed in
furnishing the excess of calcareous matter; a transmutation depending
on the absorption of an unknown principle, to the amount of nearly five
times in its own weight *.

CX. A substance to be fit for our nourishment, should be capable of
decomposition and fermentation ; that is, capable of ^undergoing an in-
ward and spontaneous change, so that its elements and relations may be
altered. This spoutaneous susceptibility of decomposition, excludes from
the class of aliments, whatever is not organized and is not a part of a
living body, thus, mineral substances absolutely resist the action of our
organs, and are not convertible into their own substance. The common
principle extracted from alimentary substances, however varied they may
be, the aliment, as Hippocrates terms it, is most probably, a compound
highly subject to decomposition and fermentation ; this is likewise, the
opinion of all those who have endeavoured to determine its nature. Lorry
thinks it a mucous substance ; Cullen says it is saccharine ; Professor
Halle considers it as an hydro-carbonous oxyde, which differs from the
oxalic acid, only in containing a smaller quantity of oxygen. It is evi-
dent, that these three opinions are very much alike, since oxygen, car-
bon, and hydrogen, combined in different proportions, form the mucous
saccharine substances and the base of the oxalic acid. On analyzing the
animal substance, by means of the nitric acid, it is reduced to this last
base, by depriving it of a considerable quantity of azote which constitutes
its most remarkable character.

But whence comes this enormous quantity of azotef ? How happens it,
that the flesh of a man living exclusively on vegetables, contains as much
azote and ammonia, and is as putrescent, as that of a man Jiving on ani-
mal food ? Respiration does not introduce a single particle of azote in our
fluids; this gas comes out of the lungs as Unentered ; the oxygen alone is
diminished in quantity. Might not one suspect that this element of ani-
mal substances is a product of the vital action, and that instead of re-
ceiving it from our aliments; we form it within ourselves, by an act that
is hijjicr-chemical; that is, which chemistry cannot imitate J ?

CXI. It has been maintained, that the hydro-carbonous oxide, com-
"bines, in the stomach and intestinal canal with oxygen, whether this last
principle has entered, with the aliments, into the digestive tube, or whe-
ther it is furnished by the decomposition of the fluids within that cavity.

* See the Jlnnales tls CMnue, a^d the Systtme des Connaissances Cfdmiqnes cle Four-
croy. Tome X. page 7'2.

•j- The late experiments of Messrs. Allen and I'cpys prove, that when an animal is
made to breathe pure oxygen, the blood disengages a certain quantity of azote, and ab-
sorbs an equal quantity of oxygen. Philosophical Transactions, 1809 — Copland.

\ The question asked by the author is not philosophical. Either the elements of azote
must be furnished by the 'aliment or atmosphere, or else the azote itself must thus be
introduced. Otherwise we must admit that the vital power can create, azote without
materials, or from nothing, which is-absurd. — Godmpn.

The intestinal fluids extricate azote which combines with the alimentary
mass, and occupies the place of the carbon which the oxygen has taken
from it, to form carbonic acid. On reaching the lungs, and being again
exposed to the action of the oxygen of the atmosphere, this gas robs it
of a portion of its carbon, and as it disengages the azote of the venous
blood it brings about a new combination of that principle with the chyle.
Lastly, propelled with the blood to the surface of the skin, the atmos-
pherical oxygen disengages its carbon, and completes its azotisation. —
The cutaneous organ is perhaps to the lymphatic system, what the pul-
monary organ is to the sanguineous system.

The animalization of the animal substance is therefore effected, princi-
pally by the loss of its carbon, which is replaced by the excess of azote
in the animal fluids. These maintain themselves, in this manner, in a
due temperament ; for, continually parting with the carbonous principle
in the intestinal, pulmonary, and cutaneous combinations, they would be
over animalized, if an additional quantity of chyle did not seize the azote,
which is in excess. Still, this theory does not account for the formation
of the phosphoric salts, of the adipocire, and a variety of other products;
but without adopting it, to the full, one may presume, from the experi-
ments and facts on which it rests, that the oxygen of the atmospherical
air is one of the most powerful agents employed by Nature, in the trans-
formation of the aliments we live upon, into our substance.

How are those animals nourished which live solely on mere animalized
flesh, that is, containing a greater quantity of azote, and a greater pro-
portion of ammonia than their own substance. In such a case, the assi-
milation of the aliments, consist in their disanimalization either, by the
co-operation of all the organs, or by the sole action of the digestive or-
gans, by the combination of the gastric juice with the other fluids.

The constituent elements entering into the composition of our organs,
whether coming from the exterior, or formed by the vital power itself,
are thrown out of our body, by the different emunctories, and cease to
form a part of it, after remaining within it, for a limited time. The urine
carries along with it, an enormous quantity of azote, the lungs and the
liver rid us of the carbon and of the hydrogen; the oxygen which con-
tains eighty-five parts in the hundred, in the composition of water, is
evacuated by means of the aqueous secretions which carry off, in a state
of solution, the saline and other soluble principles.

Among those salts there is one, but little soluble, and which, neverthe-
less, is of primary consequence among the constituent principles of the
animal economy. Phosphate of lime, in fact, forms the base of several
organs, it almost entirely, forms the osseous system, at an advanced pe-
riod of life; all the white organs, all our fluids contain a remarkable
quantity of that substance, of which the economy rids itself by a kind of
dry secretion. The outer covering is, in all animals, the emunctory des-
tined for that purpose; the annual moulting of birds, the fall of the hair
of quadrupeds, the renovation of the scales of fishes and reptiles, carry
off, every year, a considerable quantity of calcareous phosphate. Man is
subject to the same laws, with this difference, that the annual desquama-
tion of the epidermis, is not under the absolute influence of the seasons,
as in the brute creation. The human epidermis is renewed annually, as
well as the hair on the head and on the body; but this change is brought
about gradually, and is not completed in a season ; it does not take place
in the spring, as in most animals, nor in autumn with the fall of the leaf,

328

though at these two periods, the hair falls off in greatest quantity, and
ihe desquamation of the cuticle is more active. These two phenomena
last throughout the whole year, as in southern climates, the fall of the
leaves and the renovation of vegetation are continually going on. As will
be mentioned, in speaking of the functions of generation, man living in
a state of society, and enjoying all the advantages of civilization, is not
as much under the influence of the, seasons as the inferior animals. One
cannot, however, but observe, that the successive shedding and renewing
of the epidermoid parts, as the cuticle, the nails, and the hair, are among
the most effective means which nature possesses of parting with the phos-
phate of lime, so abundant in all animals, and which, nevertheless, is so
insoluble, and consequently so unfit to be carried out of the system, along
with the excrementitious fluids. This effect is very remarkable, on the
termination of several diseases, in the salutary renovation of the solids
and fluids which takes place during convalescence. The hair ceases to
grow on the bald head of an old man; his perspiration diminishes; may
not this be the cause of the great quantity of calcareous salts, of the os-
sification of the vessels, of the induration of the membranes ?

CXII. What is the ultimate results presented to us, by this series of
functions, linked together, growing outof*one another, and all acting on
the matter of nutrition, from the moment it is received within the body,
till it is applied to the growth and reparation of its organs*? It shows
us man living within himself, nnremittingly employed in converting, into
his own substance, heterogeneous substances, and reduced to an existence
purely vegetative, inferior even to the greater part of organized beings,
in his powers of assimilation. But how high is he not placed above them
all, in the exercise of those functions we are now about to contemplate,
functions, which raise him above his own nature, which enlarge the
sphere of his existence, which serve him to provide for all his wants, and
to keep up, with all Nature, those manifold relations which subject her
to his empire f!

* Intimately connected with the consideration of nutrition is that of reproduction.
This phenomena takes place to a very -limited extent, indeed, in the more perfect ani-
mals ; but as we descend in the scale of creation, we find that the destruction of a
member or part of the body of an animal is, after a time, followed by a partial, or entire
reproduction of the part destroyed : and amongst the lowest class of animals, even a
portion only of the body becomes a perfect animal, and presents the specific characters
of the parent. In this respect, the phenomena of .animal life, as we descend through its
gradations, approach those of vegetable existence. — Copland.

f For further observations on Nutrition, see APPENDIX, Notes S and C C.

FIRST CLASS.

SECOND ORDER.

I

FrxcTioKs WHICH TESB TO THE PRESERVATION

BY ESTABLISHING HIS RELATIONS WITH THE BBISGS
THAT STTBHOITSB HIM.

231

CHAPTER VII.

OF SENSATIONS.

CXIII. WE have already seen, how the human body, essentially change-
able and perishable, maintains itself in its natural economy, carries on
its growth, and supplies its decay, by assimilating to its own substance,
principles that are yielded to it by the food it digests, and by the air it
breathes. We shall now proceed to examine, by what organs man is
enabled to keep up, with all nature, the relations on which his existence
depends; by what means he is made aware of the presence of objects
which concern him, what means he possesses to fit his connexion with
them to his welfare, to draw them towards him or to repel them, to ap-
proach or to avoid and escape them, as he perceives in them danger, or
the promise of enjoyment.

Man possesses, in all its plenitude, this new mode of existence, which
is denied to vegetable Nature. Of all the animals it is he that receives
impressions the most crowded and various, that is most filled with sen-
sations and that employs :hem, with the most powerful combination, as
the materials of thought, and the sources of intelligence : he is the best
organized for feeling the action of all beings around him, and re-acting
on them in his turn. In the study which we are about to undertake, we
shall see many instruments placed on the limits of existence, on the sur-
face of the living being ready to receive every impression; conductors,
stretching from these in s~.ru ments to one common centre, to which all is
carried; conductors through which this central organ regulates the ac-
tions, which now transport the whole body from one place to another
(locomotion} ; now merely change the relative situation of its parrs (fiar-
tial motion); and, at othe* times, produce, in the organs, certain disposi-
tions, of which speech and language, in their various forms, are the
result.

CXIV. If we are thoroughly to understand the mechanism of this ac-
tion of outward objects on our body, we must follow the natural succes-
sion of the phenomena of sensation; studying first, the bodies which pro-
duce the sensitive impression, examining next, the organs that receive
it, and next the conductors which transmit it to a particular centre, whose
office is perception. To take the sense of sight, for instance, we can
never understand how it is that light procures us the knowledge of cer-
tain qualities of bodies, if we have not learnt the laws to which that fluid
is subjected, if we know nothing of the conformation of the eyes, of the
nerves by which those organs communicate with the brain, and of the
brain itself, whither all sensations, or rather the motions in which they
consist, are ultimately carried.

CXV. Of light. At this day, the greater part of Natural Philosophers
consider it as a fluid impalpable from its exceeding tenuity. Many be-
lieve it to be only a modification of caloric, or of the matter of heat ; and
this last opiniou has received much plausibility from the late observa-

232

tions of Herschel*. I shall not examine whether, as Descartes and his
followers imagine, light, consisting of globular molecules, exist of itself,
uniformly diffused through space, or as Newton has taught us to believe,
it be but an emanation of the sun and fixed stars, which throw off, from
their whole surface, a part of their subsistence, without ever exhausting
themselves by this continual efflux : It is enough for us to know, 1st, that
the rays of this fluid move with such velocity, that light passes, in a
second, through a distance of seventy-two thousand leagues, since, ac-
cording to the calculation of Roemer and the tables of Cassini, it traver-
ses in something less than eight minutes, the thirty-three millions of
leagues that separate us from the sun; 2dly, that light is called, direct,
when it passes from the luminous body to the eye, without meeting any
obstacle ; reflected, when it is thrown back to that organ, by an opake
body; refracted, when its direction has been changed, by passing from
one transparent medium to another of different density; 3dly, that the
rays of light are reflected at an angle equal to that of incidence ; that a
ray, passing through a transparent body, is more strongly refracted, as
the body is more convex on the surface, denser, or of more combustible
elements. It was from this lest observation, mat Newton conjectured
the combustibility of the diamond, and the existence of a combustible
principle in water, since placed beyond doubt, by the beautiful experi-
ments of modern chemistry ; 4thiy, that a ray of light refracted by a
glass prism is decomposed into seven rays, red, orange, yellow, green,
blue, indigo, and violet. Each of these rays is less refrangible, as it is
nearer to the red. This ray is of all, that which strikes the eye with the
greatest force, and produces on the retina the liveliest impressions. The
eagerness of savages for stuffs of this colour is well known. Among al-
most all nations it has dyed the mantle of King? : it is the most brilliant
and splendid of all : there are animals whose e^es seem scarcely to sus-
tain it: I have seen maniacs whose madness, [after a long suspension,
never failed to break out, at the sight of a red cloth, or of one cloathed in
that colour. Green is, on the contrary, the softest of colours; the most
permanently grateful ; that which least fatigued the eyes; and on which

they will longest and most willingly repose
been profuse of green, in the colouring of all
some sort, of this colour, the greater part of th

When the eyes bear uneasily the glare of too i

.ccordingly, Nature has
lants; she has dyed, in
; surface of the globe. —

this colour are used to soften the impression, which slightly tinge, with

their own hue, all the objects seen through then
last in the scale, of which the middle place isfi

trong a light, glasses of

Lastly, the violet ray,
ed by the green, is of all

the weakest, the most refrangible. Of all colouts, violet has the least lus-
tre; forms show to less advantage under it; their prominences are lost;
painters accordingly make but little use of it. "V^hen an enlightened body

* This celebrated Astronomer has published, in the Philosophical Transactions of the
Royal Society for 1800, a series of experiments, which show, that the different coloured
rays, heat, in different degrees, the bodies on which they tall, and tJuit the red my,
which is the least refrangible, gives also the greatest heat.

The thermometer placed out of the spectrum and towards the red ray, so that it
would receive any rays yet less refrangible, rises higher than when it is placed in that
colour, From waich Herschel concludes that rays are given out by the sun, too little
refrangible to produce the sensation of light, and of colours, but which produce the
Sensation of heat — Author's J\f"otr.

233

reflects all the rays, the sensations they might separately produce, blend
into the sensation of white; if it reflects a few, it appears differently co-
loured, according to the rays it repels ; finally, if all be absorbed, the sen-
sation of black is produced, which is merely the negation of all colour.
A black body is wrapped in utter darkness, and is visible only by the
lustre of those that surround it; 5thly, that from every point in the sur-
face of a luminous or enlightened body, there issue a multitude of rays,
diverging according to their distance, with a proportionate diminution of
their effect; so that the rays from each visible point of the body, form a
cone, of which the summit is at that point, and the base, the surface of
the eye on which they fall.

CXVI. Sense of Sight. The eyes, the seat of this sense, are so placed, as
to command a great extent of objects at once, and are enclosed in two os-
seous cavities, known by the name of orbits. The base of these cavities,
is forwards, and shaped obliquely outwards; so that their outward side
not being so ong as the others, the ball of the eye supported, on that
side, only by soft parts, may be directed outwards and take cognizance
of objects placed to a side, without it being necessary, at the same time,
to turn the head. In proportion as we descend from man in the scale of
animated beings, the shape of the base of the orbits becomes more and
more oblique ; the eyes cease to be directed forward, in short, the exter-
nal side of the socket disappears, and the sight is entirely directed out-
ward, and as the physiognomy derives its principal character from the
eyes, its expression is absolutely changed. In certain animals very fleet
in running, such as the hare, the lateral situation of the organs of vision,
prevents the animals from seeing small objects, placed directly before
them, hence those animals, when closely pursued, are so easily caught
in the snares which are laid for them.

The organ of sight consists of three essentially distinct parts. The one
set intended to protect the eye-ball, to screen it, at times, from the influ-
ence of light, and to maintain it in the conditions necessary to the exer-
cise of its functions : these parts are the eye-brows, the eye-lids, and the
lachrymal apparatus, and they serve as appendages of the organ. The
eye-ball itself contains two parts, answering very different purposes ; the
one, formed by nearly the whole globe, is a real optical instrument, pla-
ced immediately in front of the retina, and destined to produce on the
luminous rays those changes which are indispensable, in the mechanism
of vision ; the other, formed by the medullary expansion of the optic
nerve, is the immediate organ of that function. It is the retina, which
alone is affected by the impression of light, .and set in motion by the con-
tact of that very subtle fluid. This impression, this motion, this sensa-
tion is transmitted to the cerebral organ, by the optic nerve, the expan-
sion of which forms the retina.

CXVII. Of the eye-brows, the eye-lids, and the lachrymal apparatus (Tu-
tamina oculi, Haller.) The more or less dark colour of the hairs of the
eye-brows, renders that projection very well adapted to diminish the ef-
fect of too vivid a light, by absorbing a part of its rays. The eye-brows
answer this purpose, the more completely, from being more projecting,
and from the darker colours of the hairs which cover them : hence we de-
press the eye-brows, by knitting them transversely, in passing from the
dark, into a place strongly illuminated*, which causes an uneasy sensation
to the organ of sight, Hence, likewise, the custom that prevails with
some southern nations, whose eye-brows are shaded by thicker and dark-

2 G

234

er hairs, to blacken them, that they may still better answer the purpose
for which they are intended.

The eye-lids are two moveable curtains, placed before the eyes which
they alternately cover and uncover. It was requisite that they should be
on the stretch, and yet capable of free motion ; now, both these ends are
obtained by the tarsal cartilages, which are situated along the whole of
their free edges, and of the muscles which enter into their structure*.
The cellular tissue, which unites the thin and delicate skin of the eye-lids
to the muscular fibres, contains, instead of a consistent fat, which would
have impeded its motion, a gelatinous lymph, which, when in excess,
constitutes oedema of the eye-lids. The tissue of the eye-lids is not abso-
lutely opaque, since, even when strongly drawn together, and completely
covering the globe of the eye, one may still discern through their texture,
light from darkness. On that account, light may be considered as one of
the causes of awakening, and it is of consequence to keep in the dark,
patients fatigued by want of sleep.

The principal use of the eye-lids is to shade the eyes from the continu-
al impression of light. Like all the organs, the eyes require to recruit
themselves by repose; and they had not been able, to enjoy it, if the in-
cessant impression of the luminous rays had continually excited their
sensibility. The removal of the eye-lids t is attended with loss of sleep.
The fluids are determined to the affected organ which suffers from in-
cessant irritation. The eyes inflame, the inflamation spreads towards the
brain, and the patient expires in the most dreadful agony. Thanks to an
advanced state of civilization, these barbarous tortures have long been
abolished ; but what happens, when from ectropium of one or other of
the eye-lids, a small portion of the sclerotic coat or cornea remains un-
covered, proves the indispensable necessity of those parts. The spot ex-
posed to the continued action of the air and of the light, becomes irritat-
ed and inflamed, and there comes on an ophthalmia, which can be cured
only, by bringing together, by means of a surgical operation, the divided
edges of the opening which is the cause of the affection. From the move-
able edges of both eye-lids, there arise short curved hairs, of the same
colour as those of the eye-brows; they are called eye-lashes, and are in-
tended to prevent insects, or other very light substances, floating in the
atmosphere, from getting between the eye-ball and the eye-lidst.

The anterior part of the eye, thus defended against external injuries,
is continually moistened by the tears. The organ which secretes this
fluid, is a small gland situate in a depression at the anterior and external
part of the arch of the orbit, imbedded in fat, and supplied with pretty
considerable vessels and nerves in proportion to its bulk, and pouring the
fluid it secretes, by means of seven or eight ducts which open on the
internal surface of the upper eye-lid, by capillary orifices directed down-
ward and inward. The tears are a muco-serous fluid, rather heavier than

* Dr. Horner of Philadelphia, has lately discovered a beautiful muscle arising from the
os unguis, and inserted into the cartilage of the upper and lower lids, as far as the punc-
ture and commencement of the lachrymal duct. The office of this muscle seems to be
that of tightening the edge of the cartilages so as to apply them closely to the ball of the
eye. He has named it Tensor Tarsi. See his Practical Anatomy, p. 116.— Godman.

f A mode of punishment adopted by the ancients, especially the Carthaginians.

* They also absorb and intercept some of the luminous rays, and thus diminish the
hurtful effects of too strong a light.

235

distilled water, saltish, changing to a green colour, vegetable blues, and
containing soda, muriate, and carbonate of soda, and a very small quan
tity of phosphate ot soda and of lime*.

In ophthalmia, the irritation of the conjunctiva, transmitted by sympa-
thy, to the lachrymal gland, not only augments the quantity of its secre-
tion, but appears, likewise, to alter the qualities of the fluid that is se-
creted. The tears which, in those cases, flow in such profusion, bring
on a sense of burning heat in the inflamed part; do they not, perhaps,
contain a greater quantity of the fixed alkali then in the ordinary state of
the parts, and may not the painful sensation depend as much on the in-
creased proportion of soda in the tears, as on the greater sensibility of
the conj unctiva ?

This last membrane is merely a fold of the skin, which is exceedingly
thin, covers the posterior surface of the eye-lids, and is then reflected over
the anterior surface of the eye, which it thus unites to the eye-lids. From
the whole extent of this surface, there oozes an albuminous serosity, which
mingles with tears, and adds to their quantity!.

The tears are equably difused over the globe of the eye, by the alter-
nate motions of the palpebrae ; they prevent the effects of friction, and
save the organs of sight from being dried, at that part which is exposed
to the air. The air dissolves and carries off, by evaporation, a part of
the lachrymal fluid. This evaporation of the tears is proved by the weep-
ing to which those in whom that secretion is very profuse, are subject,
whenever the atmospherical air, from being damp, does not carry off a
sufficient quantity of the fluid. The unctuous and oily fluid, secreted by
the meibonian glands, smears the loose edge of the palpebrae, prevents
the tears from falling on the cheek, and answers the same purpose as the
greasy substances with which one anoints the edges of a vessel, filled
above its level, to prevent the overflowing of the contained fluid.

The greatest part of the tears, however, flow from without inward and
towards the inner canthus of the eye ; they take that direction in conse-
quence of the natural slope of the moveable edge of the palpebrae of the
triangular groove, which is formed behind the line of union of the edges
whose round and convex surfaces touch each other only in a point, and
this course of the tears is likewise promoted by the action of the palpebral
portions of the orbicularis palpebrarum, whose fibres, having their fixed
point at the inner angle of the orbit, where the tendons is inserted, al-
ways draw inward their external commissure.

* " The saline parts amount only to about 0 01 of the whole. The mucus contained
in the tears has the property of absorbing oxygen from the atmosphere, and of becom-
ing thick and viscid, and of a yellow colour. This property of acquiring new properties
from the absorption of oxygen explains the changes which take place in tears in some
diseases of the eye." See the Chapter, at the end of the APPENDIX, on the Chemical
Constitution of the Textures and Secretions. — Copland.

f There is no opening in the skin at the part which corresponds to the globe of the
eye; it is exceedingly thin, and is continued, under the name of the conjunctiva, over
the transparent cornea, to which it adheres so firmly, that it is not easily separated from
it. In some animals that have no palpebrx, the skin is continued, of the same thickness,
over the tore part of the eye. The conjunctiva (if, however, this portion of skin de-
serves that name) when opaque, renders the globe of the eye, in other respects imper-
fect, absolutely useless. This is observed in the kind of eel called in books of natural
history, mnrena cceciUa: the gastrobranchus ccecus is blind from the same circumstance.
M. BIBKS is of opinion that it terminates at the circumference of the cornea 1

236

Oft reaching the internal angle of the palpebrae, the tears accumulate its
the lacus lachrymalis, a small space formed between the edges of the pal-
pebrae, kept separated from each other by the caruncula lachrymalis.
This last substance, long considered by the ancients as the secretory organ
of the tears, is merely a collection of mucous cryptae covered over by a
loose fold of the conjunctiva. These follicles, alike in nature to the mei-
bomian glands, secret like them, an unctuous substance which smears the
rnoveable edges of the pa'lpebrse, near the internal commissure. The
edges of the eye-lids, in this situation, require a thicker coating, as the
tears accumulated in that spot have no where a greater tendency to flow
on the cheek.

Near the union of the inner sixth of the free edge of the palpebras
with the remaining five-sixths, at the outer part, where their internal,
straight, or horizontal portion unites with the curved part, there are situ-
ated two small tubercles, at the top of each of which there is a minute
orifice. These are the puncta lachrymalia, and they are called superior
and inferior, according to the palpebrse to which they belong. In the
dead body, the puncta do not appear to be tubercular, the small bulgings
produced, doubtless, by a state of orgasm and of vital erection, collapse at
the approach of death. These small apertures, directed inward and back-
wards, are incessantly immersed in the accumulated tears, absorb them and
convey them into the lachrymal sac, by means of the lachrymal ducts of
which they are the external orifices. The absorption of the tears, and
their flow into a membranous reservoir lodged in the groove formed by the
os unguis, do not depend on the capillary attraction of the lachrymal
ducts 5 each of them, endowed with a peculiar vital action, takes up, by a
real process of suction, the tears accumulated in the lacus lachrymalis,
and determines their flow into the sac. The weight of the fluid, the
effort of the columns which succeed each other, co-operate with the action
of the parietes of the duct. The flow of the tears is further facilitated by
the compression and slight concussions attending the contractions of the
palpebral fibres of the orbicularis, behind which the lachrymal ducts are
situated. This vitality of the puncta lachrymalia and of the ducts is rea-
dily discovered, when we attempt to introduce into them Anel's syringe or
Mejean's stylet, to remove slight obstructions of the lachrymal passages,
In a child now under my care, fora mucous obstruction of the nasal duct,
I can see the puncta lachrymalia contract, when the extremity of the
syphon does not, at once, enter the canal. One is then obliged to wait,
before it can be introduced, for a cessation of the spasmodic contraction,
sac, which lasts but a few moments. The tears which which flow into
the lachrymal by the common orifice of the united puncta lachrymalia,
never accumulate within it, except in case of morbid obstruction; they,
in that case, at once enter into the nasal duct, which is a continuation of
it, and fall into the nasal fossae, below the anterior part of the inferior
turbinated bones of these cavities. There, they unite with the mucous
of the nose, increase its quantity, render it more fluid, and change its
composition. The use of the tears is to protect the eye-ball against the
irritating impression of the immediate contact of the atmosphere. They,
at the same time, favour the sliding of the palpebrae, lessen the friction
in those parts and in the eye-ball, and thus promote their motion.

CXVIII. Of the globe of the eye. The eye-ball, as was already ob-
served, may be considered as a dioptrical instrument placed before the
retina ; whose office it is to refract the luminous rays, and to collect them

237

into one fasciculus, that may strike a single point of the nervous membrane
exclusively calculated to ieel its impression. An outer, membranous,
hard, and consistent covering supports all its parts. Within the first mem-
brane called the sclerotic, lies the choroid, adarkish coat, which lines the
inside of the sclerotic, and forms the eye into a real camera obscura*.
At the anterior part of the globe, there is a circular opening in the sclerotic
in which the transparent cornea is inserted. At about the distance of the
twelfth part of an inch from this convex segment, received in the anterior
aperture of the sclerotica, lies the iris, a membranous partition placed
perpendicularly, and containing a round opening, (the pupil) which di-
lates or contracts, according to the state of dilatation or contraction of
the iris.

At the distance of about half a line from the back part of the iris, to-
wards the union of the anterior fourth of the globe of the eye with the
posterior three fourths, opposite to the opening of the pupil, there is
situated a lenticular body, enclosed in a membranous capsule, immo-
veably fixed in a situation by adhering to the capsule of the vitreous hu-
mour.

Behind the crystalline lens, the posterior three fourths of the cavity of
the eye contain a viscid transparent humour, enclosed in the cells of a
remarkably fine capsule, called hyaloid. This vitreous humour forms
about two-thirds of a sphere from which the anterior segment had been
taken out; the pulpous expansion of the optic nerve, the retina, is spread
out on its surface, so as to be concentrical to the choroid and sclerotic
coats.

The eye-ball being nearly spherical, the length of its different diameters
differs but little. The diameter of the eye, from the fore to the back
part, is between ten and eleven lines : the transverse and vertical diame-
ters are somewhat shorter. Within the space measured by the diameter
from the fore to the back part, there are situated, taking them in their
order from the fore part, the cornea, the aqueous humour contained in
the anterior chamber, the iris and its central opening or pupil ; the aque-
ous humour of the posterior chamber ; the crystalline lens, surrounded
by the ciliary processes ; then, the vitreous humour in its capsule, and
behind those transparent parts of the eye, through which the luminous
rays pass, in approaching to a perpendicular, are the retina which re-
ceive the impression, the choroid whose black point absorbs the rays
that pass through the thin and transparent retina, and the sclerotic
in which there is an opening for the passage of the optic nerve to the
globe of the eye.

The cornea, contained in the anterior aperture of the sclerotica, like
the glass of a watch case within its frame, is about the third of a line in

* GMKLIN (Schweigger's Journ. x. 507.) made an interesting1 set of experiments, in
order to determine the composition of the black pigment which lines the choroid coat
of the eye.

"Its colour, "he informs us, " is blackish brown, is tasteless, and adheres to the
tongue like clay ; is insoluble in water, alcohol, ether, oils, lime-water, and distilled
vinegar. It dissolves in potash and ammonia when assisted by heat, and is again preci-
pitated by acids. Sulphuric acid dissolves it, and changes its colour to redish-brown.
When distilled, it yields water, a brown oil, and carbonate of ammonia. It gives out,
at the same time, carburetted hydrogen, carbonic oxyde, azotic and oxygen gasses.
The coal remaining in the retort, consists almost entirely of charcoal." — Copland,

238

thickness $ it forms, at the fore-part of the eye, the segment of a smaller
sphere : behind it lies the aqueous humour which fills what are called the
chambers of the eye; these form spaces divided into anterior and poste-
rior, the former, which is the larger of the two, bounded by the cornea
at the forepart, and by the iris at the back part; the latter, which is
smaller, and separates the crystalline humour from the iris, the posterior
part of which, covered by a black pigment, is called the uvea*. The spe-
cific gravity of the aqueous humour does not much exceed that of dis-
tilled water; some have even thought it less ; it is albuminous, and holds
in solution several saline substances!. The chrystalline, enclosed in its
membranous and transparent capsule, is a lenticular body rather solid
than fluid ; its consistence is particularly great to ward s4its -centre; it there
forms a kind of nucleus, on which are laid several concentric layers,
whose density diminishes as they approach the surface, where the ex-
ternal layers, truly fluid, form what Morgagni considered, as a particu-
lar liquid on which the lens might be nourished by a kind of imbibition.
This body, composed of two segments of unequal convexity, about two
lines in thickness, as its centre, consists, of an albuminous substance coa-
gulable by heat and alcohol $. Extremely minute arteries given off by
the central artery of Zinn, pass through the vitreous humour, and bring
to it the materials of its growth and reparation§.

* Some anatomists have doubted the existence of the posterior chamber of the eye ;
but to be convinced of its existence, one need but freeze an eye, when there will be
found a piece of ice between the chrystalline lens and the uvea. The formation of this
icicle is not owing to the admission, through the opening of the pupil, of the aqueous
humour which, like all other fluids, expands considerably on freezing1, for, the expan-
sion of fluids on their freezing1, being proportioned to their bulk, the vitreous humour
which freezes at the same time as the aqueous, must prevent its retrogade flow through
the pupil. Lastly, the uvea or posterior part of the iris is covered with a black point
which is easily detached from it ; now, if the anterior part of the chrystalline lens had
been in immediate contact with it, it would have been soiled by some of this colouring
matter which would have tarnished its natural transparency, indispensable to perfect
vision. It is, therefore, undeniable that there does exist a posterior chamber, which is
to the anterior in the proportion of two to five, and containing- about two fifths of the
aqueous humour, the whole of which is estimated at five grains, and that the iris forms
a loose partition between the two portions of the aqueous humour in which the dai'k
pigment of the uvea is insoluble. The aqueous humour appears to be the product of
arterial exhalation ; it is soon reproduced, as we see after the operation for cataract. —
.Author's Note.

•j- The Jlqueous Humour. Specific gravity 1.090 at a temperature of 60. From various
recent experiments, it appears to be water slightly impregnated with — 1st. Albumen ;
2d. Gelatin ; 3d. Muriate of soda. Its constituents, according- to the analyses of Ber-
zelius, are : —

Water 98.10

Albumen • a trace

Muriates and lactates .... . . 1.15

Soda, with animal matter soluble only in water . 75

100.00

Copland.

% In the human eye there are, strictly speaking-, three lenses. Two menisci and one
double convex, The anterior meniscus is formed by the cornea and aqueous humour,
occupying- all the space anterior to the double convex lens ; the posterior meniscus is
formed by the scleorotica, &c. and the vitreous humour, filling the globe of the eye
posterior to the double convex lens, or "the lens" proper.— Godman.

§ The ChrystalUne Lens. Its specific gravity is 1.100. When fresh it has little taste.
It putrifics very rapidly. It is almost completely soluble 5n water. The solution is

239

THte vitreous humour, so called from its resemblance to melted glass,
is less dense than the crystalline, and more so than the vitreous, and is in
considerable quantity in the human eye ; it appears to he secreted by the
minute arteries which are distributed to the parietes of the membrane of
the vitreous humour ; it is heavier than common water, somewhat albu-
minous and saltish*.

The sclerotica is a fibrous membrane to which the tendons which move
the globe of the eye are attached; it supports all the parts of that organ, and
these collapse and decay, whenever the continuity of its external covering
is destroyed. The use of the choroid, is not so much to avoid a covering
to the other parts, as to present a dark surface, destined to absorb the
luminous rays, when they have produced on the retina a sufficient im-
pression. If it were not for the choroid, the light would be reflected,
after having impinged on the nervous membrane, its rays would cross,
and produce only indistinct sensations. Mariotte thought that the cho-
roid was the immediate seat of vision, and that the retina was only its
epidermisf. This hypothesis would never have obtained so much cele-
brity, if, besides the objections that analogy might have furnished against
it, there had been adduced, in opposition to it, the fact observed in fishes,
in which the choroid is separated from the retina, by a glandular body,
opaque and incapable of transmitting the luminous rays. The retina
loses its form, as soon as it is separated from the vitreous humour, or
from the choroid coat, between which it is spread out as a very thin cap-
sule, so soft as to be almost fluid. A number of blood-vessels, from the
central artery of Zinn, are distributed on the nervous substance of the
retina, and give it a slight pink colour. Ought we, with Boerhaave, to

partly coagulated by heat, and gives a copious precipitate with tannin both before and
after the coagulation. Its composition, according to the analyses of Berzelius, is as
follows : —

Water 58.0

Peculiar matter - 35.9

Muriates, lactates, and animal matter soluble in ajcohdl . 2.4

Animal matter soluble only in water with some phosphates . 1.3

Portions of the remaining insoluble cellular membrane . 2.4

100.0

The peculiar matter of the lens possesses all the chemical characters of the colouring
matter of the blood, except colour. When burnt it leaves a little ash, containing a very
small portion of iron. When its solution in water is coagulated by boiling, the liquid in.
which the coagulum was formed reddens litmus, containing free lactic acid. [Ann.
Phil. 11.385.)— Copland

* The Vitreous Humour possesses the same properties as the aqttews, even its spec,
grav. is the same, or only a very little greater. Its constituents, according to the analy-
sis of Berzelius, are : —

Water 98.40

Albumen 0.16

Muriates and lactates .... • 1.42

Soda, with animal matter soluble only in water . 0.02

100.00

Copland.

f Mr. Jacobs, of Dublin, has discovered a membrane in the eye, situated between
the choroids and retina. As no name has yet been given to it, we might without im-
propriety call it the tunica tenuissima, as it is the most delicate in the human body. —
Godman.

240

attribute to the aneurismal or varicose enlargements of those smal
sels, the spots which are seen in objects, in the disease to which Maitre
Jean gave the name of imaginations P In order to form the retina, the
optic nerve which penetrates into the globe of the eye, by piercing the
sclerotica, to which the covering given to that nerve by the dura mater
is connected; the optic nerve penetrates through a very thin membrane
perforated by a number of small holes, and closing the opening left by
the nerve, and which belongs as much to the choroid as to the sclerotic
coats; it then spreads out to furnish the expansion which lines the con-
cavity of the choroid, and covers over the convex surface of the vitreous
humour*. The whole extent of the retina, which is equally nervous and
sentient, may receive the impressions of the luminous rays, though this
faculty has, by several philosophers, been exclusively assigned to its cen-
tral part, called the optical axis or porus opticus. This central part is
easily recognized, in man, by a yellow spot discovered by Soemmering:
in the middle of this spot, situated at the. outer side of the entrance of
the optic nerve into the globe of the eye, there is seen a dark spot and a
slight depression, the use of which is not understood. This peculiar
structure, recently discovered, is met with only in the eye of man and
of monkeys.

CXIX. Mechanism and phenomena of vision. The rays of light passing
from any point of an enlightened object, form a cone of which the apex
answers to the point of the object, and of which the base covers the an-
terior part of the cornea. All the rays, more diverging, which fall
without the area of the cornea on thet eye-brows, the eye-lids, and the
sclerotica are lost to vision. Those which strike the mirror of the eye
pass through it, under a refraction proportioned to the density of the
cornea, which much exceeds that of the atmosphere, and to the convexity
of that membrane, approaching the perpendicular, they now pass through
the aqueous humour, less dense, and fall upon the membrane called the
iris. All those that fall upon this membrane are reflected, and show its
colour, different in different persons, and apparently depending on the
organic texture, and on the particular and very diversified arrangement
of the nerves, of the vessels, and cellular tissue, which enter into its
structure. None but the most central traverse the pupil and serve to
sight. These will pass that opening, in greater or less number, as it is

* The optic nerves differ very remarkably from the other cerebral pairs, both in their
thickness, and in the delicacy of their substance, which appears to be an immediate
continuation of medullary fibres of the brain, to which the meninges furnish one com-
mon envelope, and not a distant membranous canal for each fibre.

The nerves of vision cross each other before the cella tunica, in a manner similar to
the primitive crossing, which their roots, as well as those of the other nerves, undergo
in the substance of the brain. These double decussations may be said to neutralize each
other, and consequently, each optic nerve may be considered to arise primarily from
the hemisphere corresponding to the eye which it supplies. In hemiplegia, the affected
eye is not on that side of the body struck with the paralysis — it is on the opposite side
that the pupil is dilated, and this pathological phenomenon, which is easily proved in
persons who have experienced a paralytic seizure, seems to be one of the best proofs
which can be opposed to those who suppose that the optic nerves, where they approach
each other, experience an approximation of their fibres only. It may be farther argued,
in support of the actual decussation of these nerves, that the wasted optic nerve of an
eye that has been for some time in a state of atrophy can be traced towards the opposite
lobe of the brain ; and that an evident crossing of the optic nerve may be observed m
many of the classes of fishes. — Copland.

more or less dilated. Now, the pupil is enlarged or diminished, by the
contraction or expansion of the iris. The motions of this membrane
depend entirely on the manner in which light affects the retina. The iris
itself is insensible to the impressions of the rays of light, as Fontana has
proved, who always found it immovable, when he directed on it alone the
tlje luminous rays. When the retina is disagreeably affected by the lus-
tre of too strong a light, the pupil contracts, to give passage only to a
smaller number of rays: it dilates, on the contrary, in gloom, to admit
enough to make the requisite impression on the retina.

To explain the motions of the iris, it is not necessary to admit that
muscular fibres enter into its structure*; it is enough to know its vascu-
lar, spongy, and nervous texture; the irritation of the retina sympatheti-
cally transmitted to the iris, determines a more copious afflux of humours;
its tissue dilates and stretches, the circumference of the pupil is pushed
towards the axis of this opening, which becomes contracted by this vital
expansion of the membranous tissue. When the irritating cause ceases
to act, by our parsing from light into darkness, the humours flow back
into the neighbouring vessels, the membrane of the iris returns upon itself,
and the pupil enlarges the more, as the darkness is greater. '

The rays, admitted by the pupil, pass through the aqueous humour of
the posterior chamber, and soon meets the crystalline, which powerfully
refracts them, both from its density and its lenticular form. Brought
towards the perpendicular by this body, they pass on towards the retina

* Some anatomists contend, and we think justly, that two sets of muscular fibres enter
into the structure of the iris, the one radiating1, and the other orbicular. Amongst those
who have lately argued in support of this position, we may mention M MAU^OIB, of
Geneva. It appears to us, that those who deny muscularity to this part, do so in conse-
quence of a mistaken idea, which seems to be too generally adopted, viz. that no part
is really muscular, but that which possesses fibres of a similar appearance to those which
perform the function of voluntary motion. It shouldjrshowever, be kept in recollection
that involuntary muscles — those fibrous textures who'll receive only nerves proceeding,
from the ganglia, which are not supplied with voluntary nerves, and which are, conse-
quently, not directly influenced by the will — differ very essentially from voluntary
muscles in their structure. Indeed, muscular textures vary not only in their functions,
but even in their external characters, according as they are more or less plentifully sup-
plied with either class of nerves — the cerebral or ganglial. The structure also of mus-
cular parts, especially those which are removed from the influence of volition, has some
relation to the kinds of irritants by which they are designed by nature to be influenced.
Thus, th-e eye being formed with an intimate relation to the functions which it has to
perform, and to the external influences which act on it, possesses, in the structure of
its iris, a muscular texture of peculiar delicacy, and hence it is more sensible to the
irritations which accompany, and are subservient to, the right performance of this im-
portant animal function.

If the structure of the iris, the number of the soft and delicate nervous fibrils wliich
proceed to it from the lenticular ganglion, and the connexion which they form with the
retina in their course, be kept in view, we shall readily be able to comprehend the
procession of phenomena which lead to the motions of the iris. It is not improbable
that the nervous fibi-ils proceeding from the ganglia to the iris, form, with the capillary
arteries wliich supply its cellular texture, that particular organization which may be
considered as muscular; or, in other words, that these ganglia! nerves terminating
conjunctly with capillary ramifications in the delicate cellular substance of the iris
constitute, by such a disposition, its particular structure, and enable it to perform its
peculiar functions. Hence it will be seen that impressions made upon the retina, (in the
sensible state of that nervous expansion, and in proportion to the extent of its sensibility)
and transmitted to the iris, by means of the connexion which exists between the retina
and the nerves supplying the iris, cause a contraction of its circular fibres: as soon as
such impressions cease, these fibres relax, and the comparative action, in the circular and

2 H

through the vitreous humour, less dense, and which preserves, without
increasing it, the refraction produced by the crystalline lens. The rays,
gathered into one, strike on a single point of the retina, and produce the
impression which gives us the idea of certain properties of the body
which reflect them. As the retina embraces the vitreous humour, it pre-
sents a very extensive surface to the contact of the rays, which enables us
to behold, at once, a great diversity of objects, variously situated towards
us, even when we or these objects change our relative situation*. The
luminous rays, refracted by the transparent parts of the eye, form there-
fore, in the interior of the organ, a cone, of which the base covers the
cornea, and applies to that of the external luminous cone, whilst its apex
is on some point of the retina. It is conceived, generally, that the lumi-
nous cones issuing from all points of the object beheld, cross in their
passage through the eye, so that the object is imaged on the retina re-
versed Admitting this opinion, established on a physical experiment,
we have to inquire, why we see objects upright, whilst their image is re-
versed on the retina. The best explanation we possess of this phenome-
na, we owe to the philosopher Berkeley, who proposed it in his English
work, entitled Theory of Vision, Sec. In his opinion, there is no need of
the touch to correct this error into which sight ought to betray us. As
we refer all our sensations to ourselves, the uprightness of the object is
only relative, and its inversion really exists at the bottom of the eye.

radiated fibres, giving rise to certain states of pupil, is relative to the extent, to which
the irritation proceeds along1 the axis of the nerves and vessels, and affects either set of
fibres.

According to this view of the Subject, compression of the brain, or an insensible state
of the optic nerve, is followed by expansion of the pupil, because the first impression
requisite to contraction of the orbicular fibres, cannot be made, unless occasionally to a

pupil. The pup)

with worms, conformably to what is gciun-iilly observed in the animal economy, namely,
that all orbicular muscles, when no adjoining1 irritation exists, exhibit a greater or less
degree of relaxation as the vital energies are more or less diminished. It would appear,
in a debilitated state of the system, that the nervous influence proceeding from the len-
ticular ganglion, is insufficient to the 'purpose of exciting fully the orbicular fibres of
the iris, and, at the same time, the retina perhaps, possesses that low degree of sensi-
bility to the irritation of light which is followed by an adequate effect upon the nerves
supplying the iris. Indeed, it seems, under the circumstances just referred to, where
irritation is generally present in the abdominal viscera, that nervous influence is secreted
in the brain and parts adjoining in an insufficient manner, and consequently the dimi-
nished activity of the cerebral and ganglial nerves supplying the various structures of
the eye is the result. When, however, irritation exists in the brain, or when an increase
of the circulation occurs in that organ, without overwhelming- its powers, accompanied
with, or preceded by, debility, the pupil contracts, or even remains contracted, because,
in consequence of such irritation or increase of circulation in the brain and connected
parts, the sensibility and nervous activity are heightened.

* The rays of light may be said to penetrate or traverse the demi-transparent tissue
of the retina, and, as it were, to search through the nervous pulp, when they arrive at
the choroid coat, which is designed, in a great measure, to absorb these rays. Does any
intimate combination take place between the nervous pulp and the light, which may
give rise to that sensation which follows" a violent compression of the globe of the eye
in an obscure situation? The spots which are observable after having had the eye
fixed for a considerable time, on certain coloured objects, do they arise from this sort
of impregnation of the retina, or rather of a portion of it, with the rays of lighter, as is
more generally believed, has the sensibility of the retina become partially increased Or
diminished by the circumstance of inaction, or of exercise — Copland-

243

By the point of distinct vision, is understood the distance at which we
can read a book of which the characters are of middling size, or distin-
guish any other object equally small. This distance is not confined within
very narrow limits, since we can read the same book at six inches from
the eye, or at five or six times the distance. This faculty of the eyes, to
adapt themselves to the distance and the smallness of objects, cannot
depend, as has been often repeated, on the lengthening or shortening
of the globe of the eye by the muscles that move it. Its four recti
muscles are not, in any case, capable of compressing it on its sides,
nor of lengthening it by altering its spherical form; their simultaneous
action can only sink the ball in its socket, flatten it from the fore to the
back part, diminish its depth, and make the refraction, consequently,
less powerful, when objects are very distant or very small: this last effect,
even, might be disputed. The eye which moves and rests on the adipose
cushion which fills the bottom of the socket, is never strongly enough
pressed to lose its spherical figure, which of all the forms in which bo-
dies can be invested, is that which, by its especial nature, best resists
alteration. The extremities of the ciliary processes, which surround the
circumference of the crystalline lens, cannot act on this transparent lens,
compress nor move it: for, these little membranous folds, of which the
aggregate composes the irradiated disk, known under the name of corpus
ciliare, possessing no sort of contractile power, are incapable of moving
the crystalline lens with which their extremities lying in simple conti-
guity have no adherence, and which, besides, is immovably fixed in the
depression which it occupies, by the adhesions of its capsule with the
membrane of the vitreous humour. The various degrees of contraction
or dilation of which the eye-ball is susceptible, afford a much more satis-
factory explanation of this physiological problem.

The rays of light which come from a very near object, are very diver-
gent: the eye would want the refracting power necessary to collect them
into one, if the pupil, contracting by the enlargement of the iris, did
not throw off the more divergent rays, or those which form the circum-
ference of the luminous cone. Then, those, which form the centre of
the cone, and which need but a much smaller refraction for their re-union
on a single point of the retina, are alone admitted by the straightened
opening. When, on the contrary, we look at a distant object from
which the rays are given out, already very convergent, and which need
but a small refraction to bring them towards the perpendicular, we di-
late the pupil, in order to admit the more diverging rays, which, when
collected, will give the image of the object. In this respect, very small
bodies are on the same footing as those at a great distance.

Though the image of every object is traced at the same time in both our
eyes, we have but one sensation, because the two sensations are in harmony
and are blended, and serve only, one aiding the other, to make the impres-
sion stronger and more durable. It has long been observed, that sight is
more precise and correct when we use only one eye, and Jurine thinks
that the power of the two eyes united exceeds only by one thirteenth,
that of a single eye. The correspondence of affectton requires the di-
rection of the optical axes on the same objects, and be that direction
ever so little disturbed, we see really double, which is what happens in
squinting.

If the eyes are too powerfully refractive, either by the too great con-

244 ^p

vexity of the cornea and the crystalline, the greater density of the hu-
mours, or the excessive depth of the ball, the rays of light, too soon re-
united, diverge anew, fall scattering on the retina, and yield only a con-
fused sensation. In this defect of sight, called .myojiia, the eye distin-
guishes only very near objects, giving out rays of such extreme diver-
gence as to require a very powerful refractor. In firesbytia^ on the 'other
hand the cornea too much flattened, the crystalline little convex, or set
too deeply, the humonrs too scanty, are the cause that the rays are not
yet collected when they fall upon the retina, so that none but very distant
objects are distinctly seen, because the scarcely divergent rays they^give
out, have no need of much refraction.

Myopia is sometimes the effect of the. habit which some children get
of looking very close at objects which catch their attention. The pupil
then becomes accustomed to great constriction, and dilates afterwards
with difficulty. It is obvious, that to correct this vicious disposition,
you must show the child distant objects which will strongly engage his
curiosity, and keep him at some distance from every thing he looks at.

The sensibility of the retina, on some occasions, rises to such excess,
that the eye can scarcely bear the impression of the faintest light. Nyc-
taclofies, such is the name given to those affected with this disorder, dis-
tinguish objects amidst the deepest darkness 5 a few rays are sufficient
to impress their organ.

It is related that an English gentleman, shut up in a dark dungeon,
came gradually to distinguish all it contained: when he returned to the
light of day, of which he had in some sort lost the habit, he could not
endure its splendour, the edges of the pupil, before extremely diluted, be-
came contracted to such a degree as entirely to efface the opening.

When on the other hand, the retina has little sensibility, strong day-
light is requisite to sight. This injury of vision, known by the name of
hemeralofiia't, may be considered as the first step of total paralysis of the 4
oplic nerve, or gutta serena. It may arise from any thing that can impair
the sensibility of the retina. Saint-Yves relates, in his work on diseases
of the eyes, many cases of hemeralopia. The subjects were chiefly work-
men, employed at the Hotel des Monnoies, in melting the metals. The
inhabitants of the northern regions, where the earth is covered with snow
great part of the year, become at an early age hemeralopes. Both con-
tract this weakness, from their eyes being habitually fatigued by the
splendour of too strong a light.

Finally, in order to the completion of the mechanism of vision, it is re-
quisite that all parts of the eye be under certain conditions, the want of
which is more or less troublesome. It is especially necessary, that the
membranes and the humours which the rays of light are to pass through,
should be perfectly transparent. Thus specks of the cornea, the closing
of the pupil by the preservation of the membrane which stops that open-

* I give to the words nyctalopia and hemeralopia the same meaning- as all other writers
down to Scarpa, who has published the latest Treatise on diseases of the eyes. This
acceptation is, however, a grammatical error, since the two terms, nyctalopia, in its Greek
roots, signifies an affection* which takes away sight during- the night, and hemeralopia
one in which it is lost during the day. It is "accordingly in this sense that they are used
by the father of physic. I owe this remark to Dr. Houssille Chamseru, who has care-
fully verified the text of Hippocrates in the MS S of the Imperial Librarv — Author's
Note.

245

ing during the first months of the life of the foetus; cataract, ait affec-
tion which consists in the opacity of the crystalline lens or its capsule ;
the glaucoma, or defect of transparency in the vitreous humour, weak-
en or altogether destroy sight, by impeding the passage of the rays to
the retina. This membrane itself must be of tempered sensibility to be
suitably affected by their contact. The choroid, the concavity of which
it fills, must present a coating black enough to absorb the rays that pass
through it. It is to the sensible decay of the dye of the choroid in ad-
vancing years, as much as to the collapsing induration, and discolouring
of different parts of the eye, and the impaired sensibility of the retina
from long use, that we ascribe the confusion and weakness of sight in
old people. The extreme delicacy of the eyes of the Minos pro vesequally
the necessity of the absorption of light, by the black coating which cover
the choroid.

The eyes are, of all the organs of sense, those which are the most deve-
loped in a new-born child.— They have then nearly the bulk which they
j*re Ur retain during life. Hence it happens, that the countenance of chil-
dren^whose eyes are proportionably larger, is seldom disagreeable, be-
cause it is chiefly in these organs that physiognomy seeks expression.
Might we not say, that if Nature sooner completes the organ of sight, it
is because the changes which it produces on the rays of light, arising
purely from a physical necessity, the perfection of the instrument was
required for the exercise of the sense ?

The eyes are not immoveable in the place they occupy. Drawn into
very various motions, by four recti muscles, and two oblique, they direct
themselves towards all objects of which we wish to take cognizance; and
it is observed, that there is, between the muscles which move the two eyes,
such, a correspondence of action, that these organs turn^at once the same
way, and are directed, at once, towards the same object, in such a manner,
that the visual axes are exactly parallel. It sometimes happens, that this
harmony of motion is disturbed ; and hence squinting; an affection
which depending almost always, on the unequal force of the muscles of the
eye, may be distinguished into as many species as there are muscles which
can draw the globe of the eye into their direction, when from any cause,
they become possessed of a predominating power. Buffon has further as-
signed as a cause of squinting, the different aptitude of the eyes to be affect-
ed by light. According to this celebrated naturalist, it may happen, that
one of the eyes being originally of greater sensibility, the child will close
the weaker to use the stronger, which is yet strengthened by exercise,
whilst repose still weakens the one which remains in inaction. The exami-
nation of a great many young people, who had fullen under military con-
scription, and claimed exemption, on the score of infirmities, has shown me
that squinting is constantly connected with the unequal power of the eyes.
Constantly, the inactive eye is the weakest, almost useless, and it was quite
a matter of necessity that the diverging globe should be thus neutralized,
else the image it would have sent to the brain, different from that which the
sound eye gives, would have introduced confusion into the vital functions.
The squinting eye, being inactive, falls by degrees into that state of debi-
lity, from default of exercise, which Brown has so well called indirect de-
bility.

The sense of sight appears to me, much rather to deserve the name which
J. J. Rousseau has given to that of smell, of sense of the imagination.
Like that brilliant faculty of the soul, the sight, which furnishes us with

-246

ideas so rich and varied, is liable to betray us into many errors. Jt may
be doubted, whether it gives the notion of distance, since the boy couch-
ed by Cheselden, conceived every thing he saw to touch his eye. It ex-
poses us to false judgments on the form and size of objects 5 since, agree-
ably to the laws of optics, a square tower seen at a distance, appears
to us round ; and very lofty trees seen also very far off, seem no taller
than the shrubs near us. A body, moving with great rapidity, appears
to us motionless, Sec. It is from the touch, that we gain the correction
of these errors, which Condillac, in his Treatise on Sensation, has per-
haps exaggerated.

CXX. The organ of sight, in different animals, varies according to the
medium in which they live; thus, in birds which fly in the higher regions
of the air, there is an additional and very remarkable eye-lid: this is par-
ticularly the case with the eagle, which is thus enabled to look at the sun,
and with night birds, whose very delicate eye it seems to protect fromHhe
effects of too strong a light. In birds, likewise, there is a copious secre-
tion of tears, the medium in which they live causing a considerable eva-
poration. The greater part of fishes, on the contrary, have no jmq^eable
eye-lid, and their eyes are not moistened by tears, as the water in which
they are immersed, answers the same purpose, In some fishes, however,
the eyes are smeared with an unctuous substance calculated to prevent
the action of the water on the organ.

The globe of the eye in birds, is remarkable by the convexity of the
cornea, which is, sometimes, a complete hemisphere, hence it possesses
a considerable power of refraction. This power of refraction, appears to
be very weak in fishes, the fore part of their eyes being very much flat-
tened; but the water in which they live made it unnecessary, that they
should have an aqueous humour, for, the density of this fluid being near-
ly the same as that of water, it would not have produced any refraction :
besides, being, in sea-fish, of inferior density to that of salt-water, it would
have broken the rays of light, by making them diverge from the perpen-
dicular. In fact, the refractive power of a medium is never but a relative
quantity ; the degree of refraction is not determined by the density of the
medium, but by the difference of density between it and the medium that
is next to it. To make up for the flatness of the cornea occasioned by the
small quantity, or even by the absence, of aqueous humour, fishes have a
very dense and spherical crystalline humour, the spherical part of which
forms a part of a small sphere.

The eyes of birds, whose cornea is thrust out by a very copious aque-
ous humour, possess, in consequence of the presence of this fluid, a very
considerable power of refraction ; the air, in the higher regions of the air,
owing to its extreme rarefaction, being but little calculated to approxi-
mate the rays of light.

The pupil admits of greater dilatation in the cat, in the owl, in night
birds, and in general in all animals that see in the dark. The sensibility
of the retina appears, likewise, greater in those animals ; several of them
appear incommoded by the light of day, aad never pursue their prey, but
in the most obscure darkness.

The crystalline humour of several aquatic fowls, as the cormorant's, is
spherical like that of fishes, and this is not, as will be mentioned here-
after, the only peculiarity of structure in these kind of amphibious ani-
mals. Lastly, the choroid of some animals, ifrore easily separated into
two distinct lamina, than that of man, presents, at the bottom of the eye,

'247

instead of a darkish, uniformly diffused coating, a pretty extensive spot
of various colours, and in some, most beautiful and brilliant. It is not
easy to say what is the use of this coloured spot, known by the name of
tafietum.

The rays of light, reflected by this opaque substance, must, in passing
through the eye, cross those which are entering at the same time ; they
must, consequently, prevent distinct vision, or at least impair the impres-
sion, in a manner which it is impossible to determine. It has been said,
that the lower animals, provided with less perfect and often less numerous
senses than those of man, must have different ideas of the universe ; is it
not, likewise, probable, that in consequence of the indistinct vision oc-
casioned by the reflection from the tapetum, they may entertain erroneous
and exaggerated notions of the power of man ? And. notwithstanding the
power granted to man by the Creator over the lower animals, as we are
told in the book of Genesis, is it probable that those which Nature has
gifted with prodigious strength, or with offensive weapons, would obey
the lord of the creation, if they saw him in his feeble and destitute con-
dition, in a word, such as he is ?

The heads of insects with numerous eyes, are joined to their body, and
move along with it : their existence is, besides, so frail, that it was re-
quisite that Nature should furnish them abundantly with the means of
seeing those objects which may be injurious to them. We shall not en-
ter, any farther, into these remarks relative to the differences in the organ
of sight, in the various kinds of animals. More ample details on this
subject belong, in an especial manner, to Comparative Anatomy.

CXXI. Of the Organ of Hearing. Of Sound. Sound is not, like light,
a body having a distinct existence: we give the name of sound to a sen-
sation which we experience, whenever the vibrations of an elastic body
strike our ears. All bodies are capable of producing it, provided their
molecules are susceptible of a certain degree of re-action and resistance.
When a sonorous body is struck, its integrant particles experience a sud-
den concussion, are displaced and oscillate with more or less rapidity.
This tremulous motion is communicated to the bodies applied to its
surface ; if we lay our hand on a bell that has been struck by its clapper,
we feel a certain degree of this trembling. The air, which envelopes the
sonorous body, receives and transmits its vibrations with the more effect
from being more elastic. Hence, it is observed that, caeteris paribus, the
voice is heard at a greater distance in winter, when the air is dry and
condensed by the cold.

The sonorous rays are merely series of particles of air along which the
vibration is transmitted, from the sonorous body, to the ear which per-
ceives the noise occasioned by its percussion. These molecules partici-
pate in the vibrations which are communicated to them ; they change
their form and situation, in proportion as they are nearer to the body that
is struck, and vice versa; for, sound becomes weaker, in proportion to
the increase of distance. But this oscillatory motion of the aerial mole-
cules, should be well distinguished from that by which the atmosphere,
agitated by the winds, is transported and changes its situation.-—
And in the same manner as the balance of a pendulum moves inces-
santly within the same limits, so, this oscillatory motion affects the
molecules of the air within the space which they occupy, so that they
move to and fro during the presence or the absence of the vibration.
The atmospherical air, when set in motion, in a considerable mass at a

248

time, produces no sound, unless in its course, it meets with a body which
vibrates from the percussion which it experiences.

The force of sound depends, entirely on the extent of the vibrations ex-
perienced by the molecules of the sonorous body. In a large bell struck
violently, the agitation of the molecules is such, that they are transmit-
ted to considerable distances, and that the form of the body is evidently
changed by it. Acute or grave sounds are produced by the greater or small-
er number of vibrations, in a given time, and the vibrations will be more
numerous, the smaller the length and diameter of the body. Two catgut
strings, of the same length and thickness, and with an equaldegree of ten-
sion, will vibrate an equal number of times, in a given time, and produce
the same sound. This, in music, is called unison. If one of the strings is
shortened by one half, it vibrates as often again as the other, and gives out
a sound more acute, or higher by one octave. The same result may be ob-
tained by reducing the string one half of its original thickness, without
taking from its length. The vibrations will, in the same manner, be
accelerated, by giving a greater degree of tension to the sonorous
cord. The difference of the sounds produced by a bass, a harp, or any
other stringed instrument, depends on the unequal tension, length, and
size of the strings.

This division of the elementary sound is an act of the understanding,
which distinguishes, in a noise apparently monotonous, innumerable va-
rieties, and shades expressed by signs of convention. But in the same
manner as light, refracted by a prism, presents innumerable intermediate
shades, between the seven primitive colours, and as the transition is gra-
dual, from the one to the other of these colours : so the division of the
primitive sound into seven tones expressed by notes, is not absolute, and
there are a number of intermediate sounds which augment or diminish
their value, Sec.

Sound has, therefore, been analysed as well as light ; the use of the ear,
with regard to sound, corresponds to that of the prism with regard to
light, and the modifications of which sound is capable, are as numerous
and as various, as the shades between the primitive colours.

Sound is propagated with less velocity than light. The report of a can-
non fired at a distance, is heard only a moment after the eye has per-
ceived the flash of the explosion. Its rays diverge and are reflected, like
those of light, when they meet with an obstacle at an angle equal'to that
of incidence. The force of sound, like that of light, may be increased
by collecting and concentrating its rays. The sonorous rays which
strike a hard and elastic body, when reflected by it, impart to it a vibra-
tory motion, giving rise to a secondary sound, which increases the force
of the primitive sound.

When these secondary sounds, produced by the percussion of a body
at a certain distance, reach the ear, they give rise to what is called an
echo. Who is unacquainted with the ingenious allegory, by which its
nature is expressed in ancient mythology, in which echo was called,
daughter of the air and of the earth ?

CXXII. Of the Organ and Mechanism of Hearing. The organ of hear-
ing in man, consists of three very distinct parts ; the one placed exter-
nally, is intonded to collect and to transmit the sonorous rays which are
modified in passing along an intermediate cavity, between the external
and internal ear. It is within the^cavities of this third part of the organ,
excavated in the substance of the petrous portion of the bone, that the

249

nerve destined to the perception of sound, exclusively resides. The ex-
ternal ear and the meatus auditorily externus may be compared to an
acoustic trumpet, the broad part of which, represented by the concha,
collects the sonorous rays which are afterwards transmitted along the
contracted part, represented by the meatus externus. The^concha con-
tains several prominences separated by corresponding depressions ; its
concave part is not wholly turned outward, in those who have not laid
their ears flat against the side of the head, by tight bandages, it is turned
slightly forward, and this arrangement, favourable to the collecting of
sound, is particularly remarkable in savages, whose hearing, it is well
known, is remarkably delicate. The base of the concha consists of a fibro-
cartilaginous substance, thin, elastic, calculated to reflect sounds and to
increase their strength and intensity, by the vibrations to which it is lia-
ble. This cartilage is covered by a very thin skin, under which no fat is
collected that could impair its elasticity ; these prominences are connect-
ed together by small muscles : these may relax it, by drawing the projec-
tions together, and thus place it in unison with the acute or grave sounds.
These small muscles within the external ear, are the musculi helicis major
and minor; the tngicus and anti-tragicus and the transversus auris, are
like the muscles on the outer part of the ear, stronger and more marked
in timid animals with long ears. In the hare, the fibres of these muscles
are most distinctly marked, their action is most apparent in this feeble
and fearful animal which has no resource but in flight, against the dan-
gers which incessantly threaten his existence, and which require that he
should receive early intimation of the approach of danger; hence hares
have the power of making their ears assume various forms, of shaping
them into more advantageous trumpets, of moving them in every direc-
tion, of directing them towards the quarter from which the noise proceeds,
so as to meet the sounds and collect the slightest,

The form of the external ear, is not sufficiently advantageous in man,
whatever Boerhaave may have said to the contrary, to enable all the so-
rous rays, which in striking against it, are reflected at an angle equal to
that of their incidence, to be directed towards the meatus auditorius ex-
ternus. United, for the most part into a single fasiculus, and directed
towards the concha, they penetrate into the meatus auditorius externus,
and the tremulous motions which they excite in its osseo-cartilaginous pa-
rietes contribute to increase their force. On reaching the bottom of the
meatus, they strike against the membrana tympani, a thin and transparent
septum stretched between the bottom of the meatus and the cavity in
which the small bones of the ear are lodged. These small bones form a
chain of bone which crosses the tympanum from without inward, and
which extends from the membrana tympani to that which connects the
base of the stapes to the edge of the fenestra ovalis.

An elastic air, continually renewed by the Eustachian tube, fills the
cavity of the tympanum: small muscles attached to the malleus and
stapes move these bones or relax the membranes to which they are at-
tached, and thus institute a due relation between the organ of hearing and
the sounds which strike it. It will be easily conceived, that the relaxa-
tion of the membrana tympani, effected by the action of the anterior mus-
cle of the malleus, must weaken acute sounds, while the tension of the
same membrane, by the internal muscles of the same bone, must increase
the force of the grave sounds. In the same manner, as the eye by the
contraction or dilatation of the pupil, accommodates itself to the light,

2 I

250

so as to admit a greater or smaller number of its rays, according to the
impression which they produce, 59 by the relaxation or tension of the
membrane of the tympanum, or of tlje fenestra ovalis, the ear reduces or
increases the strength of sounds whose violence would affect its sensibili-
ty, in a painful manner, or whose impression would be insufficient. The
iris and the muscles of the stapes and of the malleus are, therefore,
the regulators of the auditory and visual impression ; there is as close a
sympathetic connexion between these muscles and the auditory nerve,
as between the iris and the retina*. The air which fills the tympanum
is the true vehicle of sound ; this air diffuses itself over themastoid cells,
the use of which is to augment the dimensions of the tympanum, and the
force and extent of the vibrations which the air experiences within it.

These vibrations transmitted by the membrana tympani, are commu-
nicated to those membranes which cover the fenestra ovalis, and the fe-
nestra rotunda, then, by means of these, to the fluid which fills the dif-
ferent cavities of the internal ear, and in which lie the soft and delicate
filaments of the auditory nerve or of the portio mollis of the seventh
pair.

The agitation of the fluid affects these nerves and determines the sen-
sation of grave or acute sounds, according as they are slower or more
rapid. It appears that the diversity of sounds should rather be attribu-
ted to the more or less rapid oscillations, and to the undulations of the
lymph of Cotunni, than to the impressions on filaments of different
lengths, of the auditory nerve. These nervous filaments are too soft and
too slender to be traced to their extreme terminations. It is, however,
probable, that the various forms of the internal e ar (the semi-circular canals,
the "vestibule^ and the cochlea^) have something to do with the diversity of
sounds. It must also be observed, th&t the cavities of the ear are con-
tained in a bony part, harder than any other substance of the same kind,
and well fitted to maintain, or even to augment by the reaction of which
it is capable, the force of the sonorous rays.

The essential part of the organ of hearing, that which appears exclu-
sively employed in receiving the sensations of sound is, doubtless, that
which exists in all animals endowed with the faculty of hearing. This
part is the soft pulp of the auditory nerve, floating in the midst of a ge-
latinous fluid, contained in a thin and elastic membranous cavity. It is
found in all animals, from man to the sepice. In no animal lower in the
scale of animation, has an organ of hearing been met with, although some
of these inferior animals do not seem to be absolutely destitute of that
organ. This gelatinous pulp is, in the lobster, contained in a hard and horny
covering. In animals of a higher order, its internal part is divided into
various bony cavities, in birds there is interposed a cavity between that
which contains -the nerve of hearing and the outer part of the headf, in
man and in quadrupeds, the organ of hearing is very complicated ; it is
enclosed in an osseous cavity, extremely hard, situated at a considerable

* It may be added, that this connexion is formed very nearly in the same way by
means of the retrograde branch of the fi i'th pair passing through the internal ear, as the
supra orbitar ID ranch through the orbit, to assist in supplying the iris. — Guelman.

•\ In some birds, especially the crow, magpie, and raven, the semicircular canals are
remarkably large, and cross each other in a very singular manner, as I have frequently
observed. In birds of the goose or duck tribe they are small and less peculiar, whence
it may be inferred that in birds the acuteness of hearing is very much dependent on the
size of these canals. — Gasman.

.depth, and separated from the outer part of the head, by a cavity and a
canal along which the sonorous rays are transmitted, after having been
collected into fasciculi by trumpets situated on the outside.

This kind of natural analysis of the organ of hearing, is well calcula-
ted to give accurate notions on the -nature and importance of the func-
tions fulfilled by each of its parts. ^But in the investigation of the uses
and of the relative importance of the auditory apparatus, morbid anatomy
furnishes data of an equal value with those obtained from comparative
anatomy.

CXXIII. The external ear may be removed, with impunity, in man,
and even in animals in which its form is more advantageous ; the hearing
is, at first impaired, but at the end of a few days, recovers its wonted de-
licacy. The complete obliteration of the meatus auditorius externus, is
attended with complete deafness. It is not essentially necessary for the
mechanism of hearing1, that the membrana tympani should be whole ;
persons in whom it has been accidentally ruptured, can force out smoke
at their ears, without losing the power of hearing; it may be conceived,
however, that if instead of having merely a small opening that would not
prevent its receiving the impression of the sonorous rays, nor its being
acted upon by the handle of the malleus, the membrana tympani were al-
most entirely destroyed, deafness would be the almost unavoidable conse-
quence*. If, in consequence of the obstruction of the Eustachian tube,
the air in the tympanum is not renewed, it loses its elasticity and com-
bines with the mucus within the tympanum. The cavity of the tympa-
num is then, in the same condition as an exhausted receiver, in which
the sonorous rays are transmitted with difficulty. It has been thought,
that the use of the Eustachian tube was, not only to renew the air con-
tained in the tympanum, but also transmit the sonorous rays into that ca-
vity. In listening attentively, we slightly open our mouth 5 in order, it is
said, that the sound may pass from this cavity into the pharynx and
thence reach the organ of hearing. This explanation is far from satis-
factory, for the obliteration of the meatus auditorius externus is attended
with complete deafness, which would not happen, if the Eustachian tubes
transmitted the sonorous rays. When a man listens attentively, and
with his mouth open, the condyles of the lower jaw, situated in front of
the external auditory meatus, being depressed and brought forward, the
openings are evidently enlarged, as may be ascertained by puttiug the
the little finger into one's ears, at the moment of depressing the lower
jawf. The luxation of the small bones of the ear, or even their complete
destruction, does not occasion deafness, the only consequence is a con-
fusion in the perception of sounds When, however, the stapes, the base
of which rests on the greatest part of the fenestra ovalis, or when the

* We find that a temporary obstruction of the Eustachian tube in guttural angina is
sufficient to occasion a considerable degree of deafness. In such a case, the inflamma-
tion of the mucous membrane of the pharvnx extends itself to that which lines the tube,
of which it is a continuation ; and the effect that the inflammation produces on tne
function of the organ are proportionate to the extent to which it advances in the differ-
ent compartments of the internal ear. — Copland.

f The open state of the mouth in an attentive listener by no means proves that the
sonorous rays are introduced along the Eustachian tube. Indeed, if such were the case,
the aerial pulsations arriving by this direction would strike the tympanum in an opposite
direction to those that are admitted by the external passage, and thus render the hear-
ing confused. The purpose, therefore, which the Eustachian tube performs is nothing
more than to allow the renewal of the air within the tympanum. — Copland,

252

thin membrane which closes the fenestra ovalis, or when that which
closes the fenestra rotunda is destroyed, deafness takes place in conse-
quence of the escape of the fluid which fills the cavities in which the au-
ditory nerve is distributed.

The existence of this fluid appdltafc essential to the mechanism of hear-
ing, either from its keeping thenervfte in the soft and moist state required
for the purpose of sensation, or from its transmitting to them, the undu-
latory motion with which it is agitated.

The deafness of old people, which, according to authors, depends on
the impaired sensibility of the nerves, whose excitability has been ex-
hausted by impressions too frequently repeated, appears sometimes to be
occasioned by a deficiency of this humour, and by the want of moisture
in the internal cavities of the ear. During the severe winter of 1798,
Professor Pinel opened, at the Hospital of Saltpetriere, the skulls of se-
veral women who died at a very advanced age, and who had been deaf
for several years. The cavities of the internal ear were found quite empty;
they contained an icicle in younger subjects who had possessed the power
of hearing.

Deafness may, likewise, be produced by a palsy of the portio mollis of
the seventh pair, or by a morbid condition of the part of the brain from
which this nerve arises. The mechanical explanation applied by Willis
to the anomalous affections of the organ of hearing, is inadmissible, those
in which that organ is sensible only to the impression of weak or strong-
sounds acting together or separately.

This author relates the case of a woman who could not hear, unless a
great noise was made near her, either by beating a drum or by ringing
a bell; because, says he, under such circumstances, these loud noises de-
termine in the membrana tympani, which he supposes in a state of re-
laxation, the degree of tension required to enable it to vibrate under the
impression of weaker sounds. This membrane, to prevent greater re-
sistance, must be put on the stretch by the internal muscle of the malleus,
or by its own contraction. The total absence of muscular fibres in the
membrana tympani, in man, renders very doubtful this spontaneous con-
traction. Mr. Home, however, has just ascertained that the membrana
tympani of the elephant is muscular and contractile. Admitting all these
suppositions, we only substitute one difficulty for another, and it remains
to be shown, why the more powerful sounds merely increase the tone of
membrana tympani; why they do not become objects of perception of
the organ of hearing, though they might be expected to render us insen-
sible to the perception of weaker sounds.

CXXIV. Of odours. Chemists have long thought that the odoriferous
part of bodies formed a peculiar principle, distinct from all the other
substances entering into their composition; they gave it the name of
aroma; Fourcroy, however, has clearly shown, that this pretended ele-
ment consisted merely of minute particles of bodies, detached by heat
and dissolved in the atmosphere, which becomes loaded with them and
conveys them to the olfactory organs. According to this theory, all bo-
dies are odoriferous, since caloric may sublimate some of the particles of
those which are least volatile. Linnaeus and Lorry had endeavoured to
class odours, according to the sensations which they produce*; Four-

* L-innzeus admits seven classes of odours; 1st class, ambrosiac odours, those of the rose
and cf musk belong- to this class, they are characterised by their tenacity ; 2d, fragrant ,•

253

croy has been guided by the chemical nature of substances; but howevef
advantageous this last classification may be, it is difficult to include in it,
the infinite odours which exhale from substances of all kinds, and it is
perhaps as difficult to arrange them in classes, as the bodies from which
they are produced.

This being laid down on the nature of odours, it is next explained,
why the atmosphere becomes loaded with the greater quantity, the warm-
er and the more moist it is. We know, that in a flower-garden, the air
is at no time more loaded with fragrant odours, and the smell is never
the source of greater enjoyment, than in the morning, when the dew
is evaporating by the rays of the sun. It is likewise, easily understood,
why the most pungent smells generally evaporate very readily, as ether,
alcohol, the spirituous tinctures, and essential volatile oils.

CXXV. Oftheorgan of smell. The nasal fossae, within which this organ
is situated, are two cavities in the depth of the face, and extending back-
ward into other cavities, called frontal, ethmoideal, sphenoidal, palatine,
and maxillary sinuses.

A pretty thick mucous membrane, always moist, and in the tissue of
which, the olfactory nerves and a considerable number of other nerves
and vessels are distributed, lines the nostrils and extends into the sinuses
which communicate with them, and covers their parietes throughout
their windings and prominences. This membrane, called pituitary, is
soft and fungous, and is the organ which secretes the mucus of the nose;
it is thicker over the turbinated bones which lie within the olfactory ca-
vities; it grows thinner and firmer, in the different sinuses.

The smtll appears more delicate in proportion to the nasal fossae being
more capacious, the pituitary membrane covers a greater space. The
soft and moist condition of this membrane is, likewise, essentially neces-
sary to the perfection of this sense. In the dog, and in all animals
which have a very exquisite sense of smell, the frontal, ethmoideal, sphe-
noidal, palatine, and maxillary sinuses, are prodigiously capacious, and
the parietes of the skull are in great measure hollowed by these different
parts of the olfactory apparatus; the turbinated bones are, likewise, very
prominent in them, and the grooves between them very deep; lastly, the
nerves of the first pair are large in proportion. Among the animals
possessed of great delicacy of smell, few are more remarkable than the
hog. This impure animal, accustomed to live in the most offensive
smells, and in the most disgusting filth, has, however, so very nice a
smell, that it can detect certain roots, though buried in the earth at a
considerable depth. In some countries, this quality is turned to advan-
tage, and swine are employed in looking for trufles. The animal is taken
to those places where they are suspected to be, turns up the earth in
which they are buried, and would feed on them greedily, if the herdsmen,
satisfied with this indication, did not drive them away from this substance
intended for more delicate palates.

for example, the lily, the saffron, and jasmine; they fly off readily ; 3d, aromatic, as the
smell of the laurel ; 4th, aliaceous, approaching to that of garlic ; 5th, fetid, as that of
valerian and fungi ; 6th, virous, as of poppies and opium ; 7th, nauseous, as that of
g-ourds, me'ons, cucumbers, and, in general, all cucurbitaceous plants.

Lorry admits orty- five kinds of odours, camphorated, narcotic, ethereal, volatile acid,
and alkaline.

M. Fourcroy admits the mucous aroma, belonging to plants, improperly termed inodo-
rous. Oihj and fugacious, oily and volatile, acid and hydro-sulpfiureous.—jlvthor's Note,

264

CXXVI. Of the sensation of odours. Do the nerves of the first pair
alone give to the pituitary membrane, the power of receiving the im-
pression of smell, and do the numerous filaments of the fifth pair, merely
impart to it the general sensibility belonging to other parts? This ques-
tion appears to require an answer in the affirmative. This pituitary
membrane, in fact, possesses two modes of sensibility, perfectly distinct,
since the one of the two may be almost completely destroyed, and the
other considerably increased. Thus, in violent catarrh, the sensibility of
the part, as far as relates to the touch, is very acute, since the pituitary
membrane is affected with pain, while the patient is insensible to the
strongest smells.

It seems probable, that the olfactory nerves do not extend into the
sinuses, and that these improve the sense of smell, merely by retaining,
for a longer lapse of time, a considerable mass of air loaded with odori-
ferous particles. I have known detergent injections, strongly scented,
thrown into the antrum highmorianum by a fistula in the alveolar pro-
cesses, produce no sensation of smell. A phial filled with spirituous
liquor having been applied to a fistula in the frontal sir. uses, gave no im-
pression to the patient. The true seat of the sense of smell is at the most
elevated part of the nostrils, which the nose covers over in the form of a
capital. There the pituitary membrane is moister, receives into its tissue
the numerous filaments of the first pair of nerves, which arising by two
roots from the anterior lobe of the brain, and from the fissure which se-
parates it from the posterior lobe, passes from the cranium through the
openings of the cribriform plate of the ethmoid bone, and terminates
forming, by the expansion of its filaments, a kind of parenchymatous tis-
sue not easily distinguished from that of the membrane. The olfactory
papillae would soon be destroyed by the contact of the atmospherical air,
if they were not covered over by the mucus of the nose. The use of this
mucus is, not merely to preserve the extremities of the nerves in a sen-
tient state, by preventing them from becoming dry, but, likewise, to
lessen the too strong impression that would arise from the immediate
contact of the odoriferous particles. It perhaps even combines with the
odours, and these affect the olfactory organs, only when dissolved in mu-
cus, as the food in saliva.

As the air is the vehicle of odours, these affect the pituitary membrane,
only when we inhale it into the nostrils. Hence, when any odour is
grateful to us, we take in short and frequent inspirations, that the whole
of the air, which is received into the lungs, may pass through the nasal
fossse. We, on the contrary, breathe through the mouth, or we suspend
respiration altogether, when smells are disagreeable to us.

The sense of smell, like all the other senses, is readily impressed in
children; though the nasal fossae are, in them, much contracted, and
though the sinuses are not yet formed. The general increase of sensi-
bility, at this period of life, makes up for the imperfect state of the or-
ganization; and it is, in this respect, with the nasal fossae, as with the
auditory apparatus, of which an important part, the meatus exturnus, is
then not completely evolved. The sense of smell is perfected by the loss
of some of the other senses; every body, for example, knows the history
of the blind man whom that organ enabled to judge of the continence of
his daughter: it becomes blunted by the application of strong and pun-
gent odours. Thus, snuff changes the quality of the mucus secreted by

255

the membrane of the nose, alters its tissue, dries its nerves, and, in the
course of time, impairs their sensibility.

The shortness of the distance between the origin of the olfactory
nerves, in the brain, and their termination in the nasal fossae, render
very prompt and easy the transmission of the impressions which they
experience. This vicinity to the brain, induces us to apply to those
nerves, stimulants calculated to rouse the sensibility, when life is sus-
pended, as in fainting and asphyxia. The sympathetic connexions, be-
tween the pituitary membrane and the diaphragm, account for the good
effects of sternutatories, in cases of apparent death.

CXXVII. Of flavours. Flavours are no less varied and no less nume-
rous than odours; and it is as difficult to reduce them to general classes
connected by analogies and including the whole*. Besides, there exists
no element of flavour, any more than an odoriferous principle. The
flavour of fruits alters as they ripen, and appears to depend on the
inward composition of bodies, on their peculiar nature, rather than on
the form of their molecules, since crystals of the same figure, but belong-
ing to different salts, do not produce similar sensations.

To affect the organ of taste, a body should be soluble at the ordinary
temperature of the saliva; all insoluble substances are insipid, and one
might apply to the organ of taste, this celebrated axiom in chemistry,
corpora non agunt nisi soluta. If there is a complete absence of saliva,
and if the body that is chewed is altogether without moisture, it will
affect the parched tongue, only by its tactile, and not at all by its gusta-
tory qualities. The substances which have most flavour, are those which
yield most readily to chemical combinations and decompositions, as acids,
alkalies, and neutral salts. When, in affections of the digestive organs,
the tongue is covered with a mucous or whitish fur, or of yellowish or
bilious colour, we have only incorrect ideas of flavours; the thinner or
thicker coating prevents the immediate contact of the sapid particles;
when they act, besides, on the nervous papillae, the impression which
they produce is lost in that occasioned by the morbid contents of the
stomach: hence every aliment appears bitter, while the bilious disposi-
tion exists, and insipid, in those diseases in which the mucous elements
prevail.

CXXVIII. Of tlie sense of taste. No sense is so much akin to lhat of
the touch, or resembles it more. The surface of the organ of taste differs
from the common integuments, only in this respect, that the chorion, the
mucous body, and the epidermis which envelope the fleshy part of the
tongue are softer, thinner, and receive a greater quantity of nerves and
vessels, and are habitually moistened by the saliva and by the mucus, se-
creted by the mucous glands contaitied'in their substances. These mu-
cous cryptas, and the nerves of the cutaneous covering of the tongue, raise
the very thin epidermis which covers its upper surface, and form a num-

* This has been attempted, though with indifferent success, by Boerhaave, Haller,
and Linnaus. Acid, s-weet, bitter, acrid, saltish, alkaline, vinous, spirituous, aromatic, and
acerb, were the terms employed by those physicians, to express the general characters
of flavours.

The flavour of any substance appears chiefly to arise from the odoriferous particles
which escape from it, during the process of mastication and deglutition, through the
posterior nares, and aftect the olfactory nerves in that situation.— Authors Note,

her of papillae distinguished, by their form, into fungous, conical^ and vtt*
lous. With the exception of the first kind, these small prominences are
formed by the extremities of nerves, surrounded by blood-vessels, which
give to these papillae the power of becoming turgid and prominent, and
of being affected with a kind of erection when we eat highly seasoned
food, or when we long for a savoury dish. The fungous papillae are
mostly situated at the remotest part of the upper surface of the tongue,
towards its root, and where it forms a part of the isthmus faucium.
The pressure with which they are affected by the alimentary bolus, in its
passage from the mouth into the pharynx, squeezes out the mucus which
lubricates the edges of the aperture, and serves to promote its passage:
these mucous follicles, fulfil, in this respect, the same office as the
amygdalae.

The upper surface of the tongue is the seat of taste: it is undeniable,
however, that the lips, the gums, the membrane lining the arch of the
palate, and the velum palati*, may be affected by the impression of cer-
tain flavours.

It is observed, in the different animals, that the organ of taste is more
perfect, according as the nerves of the tongue are larger, its skin thinner
and moister, its tissue more flexible,, its surface more extensive, its mo-
tions easier and more varied. Hence, the bone in the tongue of birds,
by diminishing its flexibility, the osseous scales of the swan's tongue, by
reducing the extent of the sentient surface; the adhesion of the tongue to
the jaws, in frogs, in the salamander, and in the crocodile, by preventing
freedom of motion, render in these animals the sense of taste duller and
less calculated to feel the impressions of sapid bodies, than in man, and
the other mammiferous animals. Man would, probably, excel all the
other animals, in delicacy of taste, if he did not, at an early period, im-
pair its sensibility, by strong drinks, and by the use of spices, and of all
the luxuries that are daily brought to our tables. The quadruped whose
tongue is covered by a rougher skin, discover better than we can, by the
sense of taste, poisonous, or noxious substances. We know, that in the
variety of plants which cover the face of the earth, herbivorous animals
select a certain number of plants suited to their nature, and uniformly
reject those which would be injurious to them.

CXXIX. Is the lingual branch of the fifth pair of nerves, alone sub-
servient to the sense of taste ? Are not the ninth pair (almost wholly dis-
tributed in the tissue of the tongue,) and the glosso pharyngeal branch of
the eighth, likewise subservient to this function ? Most anatomists, since
Galen, have thought that the eighth and ninth pair supplied the tongue
"with its nerves of motion, and that it received from the fifth, its nerves of
sensation. Several filaments, however, of the great hypoglossal nerve, may
be traced into the nervous papillae of the tongue. This nerve is larger than
the lingual, and is more exclusively distributed to this organ than the
fifth pair, to which the other nerve belongs. Havermann states that he
knew a case, in which the sense of taste was lost from the division of the
nerve of the ninth pair, in removing a schirrous gland. This case, how-

* Especially the anterior part of the palatine membrane. The naso-palatine nerve,
discovered by Scarpa, after arising from the ganglion of Meckel, and going for a
considerable distance into the nasal fossx, terminates in that thick and rugous portion
of the palatine membrane, situated behind the upper incisors, and with winch the tip
of the tongue is in such frequent contact.— .-farter'* J\foif.

ever, appears to me a very suspicious one. The patient might still have
tasted, by means of the lingual nerve, and the sense would only have been
weakened. The division of one of the nerves of the ninth pair could
render insensible, only that half of the tongue to which it is distributed,
the other half would continue fully to possess the faculty of taste.

The application of metals to the different nervous filaments distributed
to the tongue, ought, to inform us of their different uses, if, as Humboldt
suspects, the galvanic excitement of the nerves of motion, alone produces
contractions. To ascertain the truth of this conjecture, I placed a plate
of zinc within the skull, under the trunk of the nerve of the fifth pair, in
a dog that had been killed a few minutes before, and that still retained its
warmth 5 the muscles of the tongue, under which a piece of silver was
placed, quivered very slightly; those of the forehead and temples in con-
tact with the same metal experienced very sensible contractions, when-
ever a communication was made by means of an iron rod. This experi-
ment showed, that the lingual branch of this nerve was, almost solely,
subservent to the sensation of taste, which agrees with the opinion of
most physiologists, and the same inference may be drawn from the ana-
tomical knowledge of the situation of this nerve, which, almost entire-
ly, terminates in the papilla of the membrane of the tongue, and sends
very few filaments to the muscles of that organ. But though the galvanic
irritation applied to the hypoglossal nerve affected the whole tongue, in
a convulsive manner, I did not think myself justified to infer, that this
nerve was solely destined to perform its motions; as this nervous trunk
might in this part of the body, as it does in others, contain filaments both
of sensation and motion.

The tongue though an azygous organ is formed of parts completely
symmetrical; there are, on each side, four muscles (stylo, hyo, genio-
giossi, and lingual;} three nerves (lingual, glosso-pharyngeal, and hyfioglossal;)
a ranine artery and vein; and a set of lymphatic vessels precisely alike.
All these parts, by their union, form a fleshy body of a close texture, and
not easily unravelled, similar to that of the ventricles of the heart, endowed
with a considerable degree of mobility, in consequence of the numerous
vessels and nerves entering into its substance*. If we compare their num-
ber and size with the small bulk of the organ, it will be readily under-
stood, that, as no part of the bode can execute more frequent, more ex-
tensive, and more varied motions, so no one receives more vessels and
nerves. A middle line separates and marks the limits of the two halves
of the tongue, which anatomically and physiologically considered, ap-
pear formed of two distinct organs in juxta-position.

This independence of the two parts of the tongue is confirmed by the
phenomena of disease; in hemiplegia, the side of the tongue correspond-

* HAILER concluded that the tongue possesses irritability. BLUMEXBACH has lately
determined the point by direct experiment. He caused the tongue of a four-year-old
ox, which had been killed in the usual way, to be cutout while the animal was jet warm,
and at the same time, the heart, in order that he might compare the oscillatory motions
of both viscera; and when both were excited at the same time by mechanical stimuli,
the tongue appeared to survive the heart by more than seven minutes, and so vivid were
its movements, when cut across after its separation, that its motions might be compared
to those of the tail of a mutilated snake. The same phenomena were remarkable in the
divided tongue of other animals, on the application of mechanical or chemical stimuli ;
and also in that of a boy which had been bit oft' during1 a fit of violent epilepsy — Cop-
land.

2 K

ing to the half of the body that is paralyzed, loses, likewise, the power
of motion; the other retains its mobility, and draws the tongue towards
that side. In carcinoma of the tongue, one side remains unaffected by
the affection which destroys the other half; lastly, the arteries and nerves
of the left side rarely anastomose with those on the right ; injections
forced along one of the ranine arteries, fill only the corresponding half
of the organ, Sec.

CXXX. Of tfo touch. No part of the surface of our body is exposed
to receive the touch of a foreign body, without our being speedily in-
formed of it. If the organs of sight, of hearing, of smell, and of taste,
occupied only limited spaces, touch resides in all the other parts, and ef-
fectually watches over our preservation. The touch distributed over the
whole surface, appears to be the elementary sense, and all the others are
only modifications of it, accommodated to certain properties of bodies.
All that is not light, sound, smell, or flavour, is appreciated by the touch,
which thus instructs us in the greater part of the qualities of bodies
which it concerns us to know, as their temperature, their consistence,
their state of dryness or humidity, their figure, their size, their distance,
Sec. It corrects the errors of the sight and of all the other senses, of
which it may justly be called the regulator, and it furnishes us with the
most exact and distinct ideas.

The touch of which some authors have sought to consecrate the excel-
lence, by giving it the name of the geometrical sense, is not, however,
safe from all mistake. Whilst it is employed on the geometrical pro-
perties, derived from space, and that it appreciates the length, the breadth,
the thickness the form of bodies, it transmits to the intellect, rigorous
and mathematical results ; but the ideas we acquire, by its means, on. the
temperature of bodies, are far from being equally precise. For, if you
have just touched ice, another body colder than yours, will appear warm.
It is for this reason, that subterraneous places appear warm to us during
winter. They have kept their temperature whilst all things else have
changed theirs ; and as we judge of the heat of an object by its relation
not only to our own, but also to that of other bodies and of the air about
us, we find the same places warm which has appeared cold to us, in the
middle of summer.

The densest bodies being the best conductors of heat*, marble, metals,
8cc. appear colder to us than they really are, because they carry it off so
rapidly. Marble and metals, when polished, appear still colder, because,
as they touch the skin in many more points at once, they affect this ab-
straction more effectually. Every one knows the experiment of placing
a little ball between the two fingers crossed, and producing the sensation
of two different balls.

CXXXI. Of the integuments. The general covering of the whole body

* Woolly substances, &c. all felts, of which the crossing hairs confine, in some sort,
a great quantity of air, a fluid which from its gaseous state, is a very bad conductor of
heat, retain heat well -.—and, of equal thickness, a stuff of tine wool, of which the hairs
are more separated, the tissue softer, will be warmer than a stuff of coarse wool, of
which the threads, too close, form a dense body, through which cold as well as heat,
will pass with ease. It is by thus confining a certain mass of air, that snow keeps the
soil it covers, in a mild temperature, and preserves plants from the injury of excessive
cold; a physical truth which is found figuratively expressed, in the words of the Psalm-
ist, « Et dcdit ilti nivemjkanquam vestimentiim.— Gutter's JVbte.

259

is the organ of touch, which resides in the skin properly so called. The
cellular tissue which connects together all our parts, forms over the whole
body, a layer varying in thickness, which covers it, in every part; it is
called fianniculus adijwsus. As it approaches the surface, its lamina are
more condensed, are in more immediate contact with each other, and
are no longer separated by adeps. It is by the closer juxta-posidon of
the lamina of the cellular tissue, that the skin or dermis is formed, a
dense and elastic membrane, into which numerous vessels, of all kinds,
are distributed, and into which so great a quantity of nerves terminate,
that the ancients did not hesitate to consider the skin as purely nervous.

In certain parts of the body, a very thin muscular plane separates the
skin from the panniculus adiposus. This kind of panniculus carnosus
envelopes, almost entirely, the body of some animals ; its contractions
wrinkle their skin covered with hairs, these rise, vibrate, and thus are
cleared of the dust and dirt which may have gathered on them. It is by
means of a cutaneous muscle? of very complex structure, that the hedge-
hog is enabled to coil himself up, and to present to his enemy a surface
studded with sharp points : only a few scattered rudiments of an analo-
gous structure, are to be met with in the human body ; the occipito fron-
talis, the corrugator supercilii, several muscles of the face, the platysma
moides, the palmaris cutaneous may be considered as forming part of
this muscle*. We may even include the cremaster, whose expanded fi-
bres, surrounded by the dartos, have misled some anatomists to such a
degree, that they have admitted the existence of a muscular texture in
the latter. These fibres of the cremaster, produce distinct motions, in
the skin of the scrotum, wrinkle it, in a transverse direction, and, at the
same time, bring up the testicles. The platysma myoides acts, likewise,
on the skin of the neck ; lastly, the occipito-frontalis, in some men, per-
forms so distinct a motion of the hairy scalp, as to throw off a hat, a cap,
or any other covering that may be on the head. One may compare to the
panniculus carnosus, the muscular coat of the digestive tube situated,
throughout its whole length, below the mucous membrane, which is
merely a prolongation of the skin modified and softened.

But if, in man, the subcutaneous muscle, from its imperfect state, an-
swers purposes only of secondary importance, the layer of cellular adi-
pose substance, extended under the skin, gives to the latter its tension, its
whiteness, its polish, it? suppleness, favours its applying itself to tangi-
ble objects, and thus renders the touch ^nore delicate. Too hard or too
wrinkled a skin, would have applied itself in a very incomplete manner,
to bodies of a small size, and would not readily have accommodated itself
to the small irregularities of those of inconsiderable bulk. Hence the
pulp of the fingers, which is the seat of a more delicate touch, is furnish-
ed with a kind of adipose cushion supported by the nails, ready to be ap-

* In the human body, the only muscle which bears any resemblance to the pannicu-
lus carnosus of animals is the platysma myoides, a muscle of the face, arising1 below the
clavicles terminating at the angle of the mouth and sometimes reaching to the zy-
goma. As to the occipto-frontalis, also a muscle of the face, and the comigutor super-
cilii lying under it, (not to speak of the palmaris longus, having a strong fleshy belly,
with a distinct tendon, inserted into the palmar aponeurosis,) we must say, that our au,
thor has made an unnecessary and fruitless effort to find a resemblance, which really does
not exist The cvemaster is separated from the integuments of the scrotum, by a dense
process of the superficial fascia, and therefore CAKTKOT produce the transverse corruga-
tion of the scrotum.— Godman.

260

plied to polished surfaces, and to discover the slightest asperites* I have
observed the sense of touch to be very imperfect, in men wasted by ma-
rasmus, and whose hard, dry, and wrinkled skin adheres, in certain si-
tuations, to the subjacent parts.

The chemical analysis of the cutaneous tissue shows, that it does not
exactly resemble that of the cellular and membranous tissue ; it is gela-
tino-fibrous, and, with regard to its structure and to its share of contrac-
tility, it occupies a medium, between the cellular tissues and the muscular
flesh*. There arise, from the surface of ihe skin, innumerable small
papillae, fungous, conical, pointed, obtuse and variously shaped, in the
different parts of the body. These papillae are merely the pulpous extre-
mities of the nerves which terminate into them, and around which there
are distributed vascular tissues of the utmost minuteness. The papillae
of the skin, which are more distinct in the fingers and lips than else-
where, swell, v/hen irritated, elevate, in a manner, the epidermis, and
this kind of erection, which is useful when we wish to touch a substance
with great precision, may be excited by friction or by moderate heat.

The nervous or sentient surface of the skin is covered with a mucous
coating, colourless in Europeans, of dark colour, from the effects of light,
among the natives of southern climates 5 of a gelatinous nature, destined
to maintain the papillse in that state of moisture and softness favourable
to the toucfc. This mucilaginous layer, known under the name of ret-e
mucosu?n of Malpighi, seem to contain the principle which causes the va-
riety of colour in the skin of different nations, as will be observed, in
speaking of the varieties of the human species.

The reticular state of the rete mucosum may be explained in two ways;
a thin and gelatinous layer, extending on the papillar surface of the skin,
is perforated, at each nervous papilla; and if it were possible to coagulate
or to detach this coating, we should have a real sieve, or reticulated mesh
work, _with a perforation at every point, corresponding to a cutaneous pa-
pillse. The sanguineous and lymphatic capillaries, which surround the
nervous papillse, form, besides, by their connexions, a net-work, the
meshes of which are very minute and adhere to the epidermis, by a mul-
titude of small vascular filaments that insinuate themselves between the
scales of this last envelopef.

The skin would be unable to perform its functions, if an outer, thin,
and transparent membrane, the ejiidcrmis^ did not prevent it from being
over dried. This superficial co^ring is quite insensible, no nerves and
no vessels, of any kind, are found in it, and even in the present state of
science, we do not understand how it is formed, how it repairs and repro-
duces itself when destroyed. The most minute researches on its struc-
ture, merely show the existence of an infinite number of lamellae, lying
over each other, and overlapping each other, like the tiles of a roof. This
imbrication of the epidermoid lamellae, is very obvious in fishes and rep-

* See the Chapter in the APPENDIX, on the chemical constitution of the animal tex-
tures and secretions. — Copland.

| And terminate in exhaling or absorbing- pores, according as they belong-
to the arterial capillaries, or Jto the lymphatic absorbents. It is sufficient, indeed, to
remove gently the scales of the epidermis, in order to bear their orifices and procure
the absorption of any virus. It is the net-work of MALPIGHI, or rather this assemblage
of interlaced capillary vessels below the epidermis, which appears to be the seat of the
primary phenomena iji the majority of cutaneous inflammations and eruptive diseases.— r_
Copland.

tiles, the scaly skin of which is merely an epidermis whose parts are
much more coarsely shaped.

It was observed (XLII.) in the account of absorption, how much fric-
tion facilitates the absorption of substances applied to the surface of the
skin, by raising the scales of the epidermis, so as to expose the orifices of
the absorbents, whose activity, it in other respects, increases.

Haller conceives, that the epidermis is formed by the drying up of the
outer layers of the rete mucosum. Morgagni thinks it is formed by the
induration of the skin in consequence of the pressure of the atmosphere.
In objection to these hypotheses, one may inquire, how it happens, that
by the time the foetus, immersed in the liquor amnii, has attained its
third month, it is covered with such an envelope. Pressure renders the
skin hard and callous, increases considerably its thickness, as we see in
the soles of the feet and in the palms of the hands of persons engaged in
laborious employments. The epidermis reproduces itself with an incre-
dible rapidity, after falling off in scales, after erysipelas or herpetic erup-
tions, or, when removed, in large flakes, by blistering, it is renewed in
the course of a very few days. The cuticle, together with the hairs and
the nails, which may be considered as productions of the same substance,
are the only parts, in man, that are capable of reproducing themselves.
The hairs and the horns of quadrupeds, the feathers of birds, the calca-
reous matter of the lobster and of several mollusca, the shell of the turtle,
the solid sheaths of a number of insects, possess, as well as the epidermis,
this singular property. In other respects, the chemical structure of all
these parts is the same ; they all contain a considerable portion of phos-
phate of lime, withstand decomposition, and give out a considerable quan-
tity of ammonia, on being exposed to heat. The use of the epidermis is
to cover the nervous papilla?, in which the faculty of the touch essentially
resides, to moderate the too vivid impression that would have been pro-
duced by an immediate contact, and to prevent the air from drying the
skin, or from impairing its sensibility.

The dessication of the cutaneous tissue is further prevented, and its
suppleness maintained, by an oily substance, which exudes through its
pores, and is apparently secreted by the cutaneous exhalants. This unc-
tuous liniment should not be mistaken for that which is furnished by the
sebaceous glands, in certain situations, as around the nostrils, in the hol-
low of the arm-pits, and in the groins. This adipose substance, with
which the skin is anointed, is abundant and fetid in some persons, especi-
ally in those of a bilious temperament, with red hair. It is, likewise, more
copious in the African negroes, as if Nature had been anxious to guard
against the too rapid dessication, by the burning atmosphere of tropical
climates. This use of the oil of the skin, is, likewise, answered by the
tallow, the fat, and the disgusting substances with which the Canresancl
the Hottentots anoint their body, in the manner described under the name
of tattooing, by the travellers* who have penetrated into the interior of
the burning regions of Africa.

The ancients had a somewhat similar practice, and the anointing with
oil, so frequently used in ancient Rome, answered the same purpose, of

* Among1 others Kolben, Description dn Cap de Bon?ie-Es/)erance. Sparmann, Voyage
au Cap de Bonne F^perance et Chez fes Hottentots. Vaillant, Voyage dens PInterieur de

262

softening the skin, of preventing its becoming dry, or chapped*. The
pomatums employed at the present day at the toilet, possess the same ad-
vantages. The continual transudation of this animal oil renders it ne-
cessary, occasionally, to clean the skin by bathing; the water removes
the dust and the other impurities which may be attached to its surface
by the fluid which lucubrates it. It is this humour which soils our linen,
and obliges us so frequently to renew that in immediate contact with the
skin, and which makes the water collect in drops when we come out of
the bath, See.

Though the parts in which there is found the greatest quantity of sub-
cutaneous fat, are not always the most oily, and though one cannot con-
sider this secretion as a mere filtration of this adeps through the tissue of
the skin, corpulence has, however, a manifest influence on its quantity. I
know several very corpulent persons in whom it appears to be evacuated
by perspiration, on their being heated by. the slightest exertion. They all
grease their linen in less than twenty-four hours. An excess of the oily
matter of perspiration is injurious, by preventing the evacuation of the
perspiration and its solution in the atmosphere.

We all know, how, after the epidermis has been removed, the slightest
contact is painful: that of the air is sufficient to bring on a painful in-
flammation of the skin exposed by the application of a blister. The epi-
dermis, as was likewise mentioned in speaking of the absorption, placed
on the limits of the animal economy, and in a manner inorganic, serves
to prevent heterogeneous substances from being too readily admitted into
the body, and, at the same time, it lessens the too vivid action of external
objects on our organs. All organized and living bodies are furnished
with this covering, and, in all, in the seed of a plant, in its stem and on
the surface of the body, in man and animals, it bears to the skin the great-
est analogy of function and nature. Incorruptibility is, in a manner, its
essence, and is its peculiar character; and in tombs which contain mere-
ly the dust of the skeleton, it is not uncommon to find the whole, and in
a state to be readily distinguished, the thickened epidermis that forms the
soal of the foot,. and especially the heel. However, this incorruptibility
is possessed, as well as others of the qualities of the skin, by the hairs and
the nails, which may be considered as its appendages.

CXXXII. Of the Nails. The nails are, in fact, only a part of the epi-
dermis : they are continuous with it, and, after death, fall off along with
it. They are thicker and harder ; like it they are inorganic and lamel-
lated; they grow rapidly from the root towards their free extremity;
they reproduce themselves rapidly, and acquire several inches in length,
when the part beyond the ends of the fingers and toes has not been re-
moved; as is the case with the Indian fakirs. In-this state of develope-
ment, they bend over the tips of the fingers and toes, and impair the sense
of touch, whose free enjoyment is preferable to any advantages which
savages can derive from their long and crooked nails, in defending them-
selves, or in attacking animals, or tearing to pieces those which they have
killed in hunting. The nails are quite insensible, and the reason that so
much pain is felt when ths nails run into the flesh, and that the operation
of tearing them out, which is sometimes necessary, is so painful, is, that

* The reply of the old soldier is well known, who, on being asked by Augustus, how
he came to live so long, said he owed his long life to the use of \vine inwardly, and to
that of oil outwardly ; intus rino, extusoleo. — .Author's Note.

the nerves, over which the nail grows, are more or less injured when it
grows in a wrong direction. The pain from the growing of the nails into
the quick, is no proof of their being sentient, any more than the growth of
corns proves the. sensibility of the epidermis, of which they are but thick-
ened parts, become hard and callous by pressure, and which, confined in
tight shoes, press painfully on the nerves below. The nail itself may ac-
quire a considerable degree of thickness; I have seen that of a great toe
nearly half an inch thick. The use of the nails is to support the tips of
the fingers, when they are applied to unyielding substances 5 they like-
wise concur in improving the mechanism of the touch*.

CXXXIII. Of the hair on the head and on other fiarts of the body.
These parts are treated of, in the present instance, only in consequence
of their connexion with the epidermis ; as, far from improving the touch,
they interfere with it, or at least render it less delicate.

The skin, in man, is more bare than that of other animals; it is, like-
wise, least covered with insensible parts that might blunt the sense of
touch. In almost all mammiferous animals, the whole body is covered
with hair, only a small part of the human body has any hair on it, and
that in too snr«ll a quantity, and of too delicate a texture, to interfere
with the touch. Some men, however, have a very hairy skin, and I have
seen several who, when naked, looked as if covered over with the skin of
an animal, so great was the quantity of hair over the whole body, of
which no part was bare, but a small portion of the face, the palms of the
hands, and the soles of the feet. This extraordinary growth of hair, is,
in general, a sure sign of vigour and strength. In childhood there is no
hair except on the head, the rest of the body is covered with down. Wo-
men have no beard, and there is in them, a smaller quantity of hair in
the arm-pits and on the parts of generation, and scarcely any on the limbs
and trunk. But as though the matter which should provide for the growth
of the hair, were wholly applied to the hairy scalp, it is observed, that
their hair is longer and in greater quantity.

The colour of the hair varies from white to jet black; and, as will be
mentioned, in speaking of the temperaments and the varieties of the hu-
man species, this difference of colour is a test by which we judge of those
varieties. The colour of the hairs enables us to judge of their thickness :
Williof, who, with a truly German patience, was at the pains to count
how many hairs were contained in the space of a square inch, states, in
Ms dissertation on the human hair, that there are five hundred and seventy-
two black hairs, six hundred and eight chesnnt, and seven hundred and
ninety light coloured, so that the diameter of a hair, which is between
the three and seven hundredth part of an inch, is least in light hair, and

* The toe nails are favourable lo the laying1 the foot to the surface on which the body
is supported ; they, likewise, improve the sense of touch in this part. The use of the
feet is not merely to support the \veight of the body, they are also intended to guide us
in feeling1 for the plane on which we are to rest them, to enable us to judge of the solid-
ity, of the temperature, and of the inequalities of the ground on which we tread. They,
therefore, required rather a delicate sense of touch. The division of the fore part of the
foot, into several distinct and separate parts, serves to enable us to stand more firmly,
and facilitates the action of walking. 1 have seen several soldiers who lost, from severe
cold, the extremities of their feet, in crossing the Alps which separates France from
Italy. Those who had lost only their toes, did not walk so steadily, and frequently fell
in treading on uneven ground. Those who had lost one half of their feet, were obliged
to use crutches. — Author's

264

these are finer the lighter their shade. It is, likewise, observed^ that
men of a bilious constitution, with dark hair, and inhabiting warm cli-
mates, have more hair, in other parts of the body, and that it is coarser
and more greasy.

In whatever part of the body hairs may grow, they are, every where,
of the same structure, they all arise from a vesicular bulb in the adipose
cellular tissue; from this bulb containing a gelatinous lymph, on which
the hair seems to be nourished, the latter, at first divided into two or
three filaments which constitute a kind of root, comes out in a single
trunk, passes through the skin and epidermis, receiving from the latter
a sheath that covers it to its extremity, which terminates in a point.

A hair, may, therefore, be considered as an epidermoid tube filled with
a peculiar kind of marrow. This spongy stem, which forms the centre
of a hair, is a more essential part of it, than the sheaths supplied by the
epidermis. Along this spongy and cellular filament, the animal oil of
the hair and the juices on which it is repaired flow. Though we see, in
some animals, vascular branches and very small nervous filaments direct-
ed towards the root of certain kinds of hair, and lost in it, as is the case
•with the long and stiff whiskers of some of the quadrupeds, it is impos-
sible to say, whether in man, the hair or its bulbs receives vessels and
nerves. Is the human hair nourished by the imbibtion of the gelatinous
fluid contained in its bulb, or is it nourished on the fat in which the lat-
ter is imbedded? Are vessels distributed along their axis, from the root
to the extremity ? In favour of this opinion, it was usual to mention the
bleeding from the hair when cut, in the disease called plica fiohnica. But
this disease, lately observed in Poland, by tlie French physicians, appear-
ed to them a mere entangling of hair, in consequence of the filth of the
Poles, and of their habit of keeping their head constantly covered with
a woollen cap. The hairy scalp remains perfectly sound beneath the en-
tangled hair, and the only way to cure the complaint is to cut of the hair.
Fourcroy* thinks that each hair has several short branches that stand off
from it, which, according to the explanation given by Monge, favour
the matting of the hairs that are to be converted into tissues, by the pro-
cess called felting.

CXXXIV. Among the most remarkable qualities of the hair one may
take notice of the manner in which it is affected by damp air, which, by
relaxing its substance, increases its length. It is on that account, that
hairs are used for the construction of the best hygrometers. NOT must
we omit either the readiness with which they grow and are reproduced,
even after being plucked out by the roots, as I have often seen after the
cure of tinea by a painful method : nor their insulating property, with
respect to the electric fluid, of which they are vjery bad conductors , a
remarkable property, vie.wed with reference to the conjectured nature of
the nervous fluid.

The hairs possess no power of spontaneous motion by which they can
rise on the head, when the soul shudders with horror or fear; but they
do bristle at those times, by the contraction of the occipito-frontales,
which, intimately adhering to the hairy scalp, carries it along in all its
motions.

They appear totally without sensibility : nevertheless, the passions

Systems des connoissance chimgues, tome IX. p. 263.

265

have over them such influence, that the heads of "young people have turn-
ed white ^Jfcjae night before execution. The Revolution, which pro-
duced. inKiiBlance, the extremes of human suffering, furnished many
authentit^ftsXices of persons that grow hoary, in the space of a few days.
In this pBp]J»re hoariness, is the hair dried up, as in old people, when
it seems twf^B01' want of moisture and its natural juices ?

The folwHg fact seems to show, that they are the excretory organ
of some PflHRtej the retention of which might be of very injurious con-
sequence. H Bjhionk, who, every month, had his head shaved, accord-
ing to the^jMrof his order, quiting it at its destruction, went into the
army, and let his hair grow. After a few months, he was attacked with
excruciating head aches, which nothing relieved. At last some one ad-
vised him to resume his old habit, and to have his head frequently shav-
ed ; the head aches went off, and never returned.

We know, says Grimaud*, that there are' nervous head aches, which
give way to frequent cropping the hair: — when it is kept close cut, the
more active growth that takes place sets in motion stagnating juices. A
friend of Valsalva, as MorgagjJM' relates, dispelled a maniacal affection,
by having the head of the patient shaved; Casimir Medicus cured obsti-
nate gonorrhea, by the frequent shavings of the parts of generation.

The hairs partake of the inalterability, the almost indestructibility of
the epidermis. Like it, they burn with a fizzing, and give out, in abun-.
dance, a fetid ammoniacal oil. These ashes, that remain from burning
them, contain much phosphate of limef. The horns of mammiferae, the
feathers of birds, give out the same smell in burning and yield the same
products as the hair on the head and other parts; which has led to the
saying that these last were a .sort of a horny substance drawn out like
wire. Acids, but especially alkalies, dissolve them : accordingly, all na-
tions that cut the beard, first soften it, by rubbing it with alkaline and
soapy solutions.

Is the use of the hair to evacuate the superabundant nutritious matter?
The epoch of puberty and of the termination of growth, is that in which
it first springs, in many parts of the body, which were before without it.
They are, at the same time, the emunctory by which nature gets rid of the
phosphate of lime, which is the residue of the work o? nutrition. The
hairs of quadrupeds, whose urine abounds less in phosphoric salts than
that of man, seem especially to fulfil this destination. The hairs have
some analogy with the fat, which has not yet been ascertained. They are
often found accidentally developed in the fatty tumours known under the
name of steatomas. Finally, they have uses relative to the parts on which
they grow.

CXXXV. The faculty of taking cognizance of tangible qualities, be-
longs to all parts of the cutaneous organ. We have only to apply a sub-
stance to any part of the surface of our body, to acquire the idea of its
temperature, of its dryness or moisture, of its weight, its consistence, and
even its particular figure. But no part is better fitted to acquire exact
notions, on all these properties, than the handy which has ever been con-
sidered as the especial organ of touch. The great number of bones

* Second Memoir on Nutrition, p. 49.

f -De Sedibiis et Cansis, Ernst. 8. No. 7.

t See the Chapter in the APPEXDIX, on the chemical constitution of the textures, Sec.

2 L

266

that form its structure, make it susceptible of very various motion, by
\vhich it changes its form, adapts itself to the ineciualities^Lthp surfaces
of bodies, and exactly embraces them : this apt confornJ^H|s particu-
larly manifest at the extremities of the fingers Their ante^^Brt, which
is endued with the most delicate feeling, receives, from -dian and

cubital nerves, branches of some size, which end in romidedrfcxtrernitics.
close, and surrounded with a cellular tissue. The part of the fingers,
which is called their pulp, is supported by the nails; vIBps in great
number are spread through this nervo-cellular tissue, and moisten it with
abundant juices, that keep up its suppleness. When perspiration is in-
creased, it breaks out, in small drops, over this extremity of the fingers,
along the hollow of the concentric lines with which the epidermis is fur-
rowed*.

It has been attempted to explain the pleasure we feel in touching round-
ed and smooth surfaces, by showing that the reciprocal configuration of
the hand and of the body to which it is applied, is such, that they touch
in the greatest number of points possible. The delicacy of the touch is
kept up by the fineness of the epidern^s : it increases by education,
which has more power over this sense Wn over any of the others. It
is known with what eagerness a child, allowed the free use of his limbs,
stretches his little hands to all the objects within his reach, whatjpleasurc
he seems to take in touching them, in all their parts, and running over all
their surfaces. Blind men have been known to distinguish, by touch,
the different colours, and even their different shades. As the difference
of colour depends on the disposition, the arrangement, and the number
of the little inequalities, which roughen the surface of bodies that ap-
pear the most polished, and fit them to reflect such a ray of light, absorb-
ing all the others, one does not refuse to believe facts of this kind, related
by Boyle, and other Natural Philosophers.

Some parts appear endowed with a peculiar touch; such ure the lips,
whose tissue swells, and spreads out under a voluptuous contact; a vital
turgescence, explicable without the supposition of a spongy tissue in their
structure: — such are those organs which Buffon considers as the seat of
a sixth sense. In most animals, the lips, and especially the lower one,
without feathers, scales, or hair, are the organs of a sort of touch, imper-
fect at best. When the domestic quadrupeds, such as the horse, the dog,
the ox, Sec. want to judge of the tangible qualities of bodies, you will
see them apply to it the end of their nose, the only part where the exter-
nal coffering is without hsiir; the fleshy appendages of certain birds, and
many fish with the antennae of butterflies, always set near the opening of
the mouth, answer the same purpose. The tail of the beaver, the trunk of
the elephant, are in like manner, ihe parts of their body where the touch
is most delicate. Observe that the perfection of the organ of touch, en-
sures to these two animals a degree of intelligence allotted to no other

* The use of the peculiar lines of the epidermis, especially over the inside of the
lingers and palms of the hand, is rendered very evident by the effect of blisters which
sometimes cause an entire exfoliation of ihis texture. The new formed epidermis in
many instances is smooth and shining1, and the finger cannot for a considerable time be
flexed with case, until permanent folds are formed in the integuments by frequent at-
tempts to bend the finger. After some weeks a new epidermis is formed, having the
the proper lines ; and the parts are bent in every direction, without irregular doublings
of the skin — Godmav-

267

quadruped, and becomes perhaps the principle of their sociability. The
books of travellers and naturalists swarm with facts, attesting the won-
derful sagacity of the elephant. Some Indian philosophers have gone the
length of allowing him an immortal soul. If birds, notwithstanding the
prodigious activity of their life of nutrition, are yet of such confined in-
telligence, so little susceptible of durable attachment, so restive to educa-
tion, is not the cause to be assigned to their imperfection of touch ? In vain
the heart sends towards all their organs, with more force and velocity
than any other animal, a warmer blood, and endued, more remarkably,
with all the qualities which characterize arterial blood. In vain is their
digestion rapid, their muscular power lively, and capable of long continu-
ed motion; certain of their senses, as those of sight and hearing, happi-
ly disposed; touch being almost nothing with them, as also the greater
number of impressions belonging to this sense, which informs us of the
greater part of the properties of bodies; the circle of their ideas must
be extremely narrow, and their habits, and manners, much more remote
than those of quadrupeds, from the habits and manners of man.

CXXXVI. Of all the senses, the touch is the most generally diffused
among animals. All possess it. from man, who, in the perfection of this
sense, excels all the vertebral animals, to the polypus, who, confined to
the sense of touch only, has it, in such delicacy, that he appears, to use
a happy expression of M. Dumeril, to feel even light. The skin of man
is more delicate, fuller of nerves than that of the other mammiferas: its
surface is covered only by the epidermis, insensible indeed, but so thin
that it does not intercept sensation, whilst the hairs which cover so thick-
ly the bodies of quadrupeds, the feathers which* clothe that of birds, quite
deaden it. The hand of man, that admirable instrument of his intelli-
gence, of which the structure has appeared to some philosophers* to ex-
plain sufficiently his superiority over all living species: the hand of man,
naked, and divided into many moveable parts, capable of changing,
every moment, its form, of exactly embracing the surface of bodies, is
much fitter for ascertaining their tangible qualities, than the foot of the
quadruped enclosed in a horny substance, or than that of the bird, covered
with scales too thick not to blunt all sensation.

CXXXVII. Of the nerves. These whitish cords, which arise from the
base of the brain, and from the medulla oblongata, are distributed to all
parts of the body; and give them, at once, the power of moving and feel-
ing. In this analysis of the functions of the i>ervous system, the most
natural order is to consider them merely as conductors of the power of
sensation. We shall then see, in what manner tfiey transmit the princi-
ple of motion to the organs by which it is performed. The nerves arisef
from the sentient parts, by the extremities that are, in general, soft and

* See the work of Galen, de usu partium, cap. 4, 5, 6, and BuflTon, Histoii". C\'ulureUe
torn. IV. etV. 12mo.

y In considering the nerves as conductors of sensation, it is correct to say, that they
arise from sentient parts, since it is the extremity rnost distant from the brain, \vhich
experiences the sensitive imjnvssion, that it is propagated to the organ itself, along- the
course of the nerve. In attending, on the contrary, to tue phenomena of motion, the
nerves are considered to arise from the brain ; for] it is> from the centre of the circum-
ference, thst the principle of motion is transmitted to the muscles called, by Cullen,
moving extremities of the nerves. Some anatomists have considered it as a doubtful point',
whether the nerves arise from the brain and spinal marrow, or whether these parts are
formed by the union of the nerves.— Authors Note.

268

pulpy, but not alike in all, in consistence and form ; and it is to these va-
rieties of arrangement and structure, that the varieties of sensation in
the different organs are to be referred.

One may say that there exists, in the organs of sense, a certain relation,
between the softness of the nervous extremity, and the nature of the bo-
dies which produce an impression upon it. Thus, the almost fluid state
of the retina, bears an evident relation to the subtilty of light. The con-
tact of this fluid could not produce a sufficient impression, unless the
sentient part were capable of being set in motion by the slightest im-
pression. The portio mollis of the seventh pair, wholly deprived of its
solid covering, and reduced to its medullary pulp, readily partakes in the
sonorous motions transmitted to it by the fluid, in the midst of which its
filaments are immersed. The nerves of smell arid of taste are more ex-
posed, than the nervous papillae of the skin employed in receiving the
impressions produced by the coarser properties of bodies, See.

From their origin, the nerves ascend towards the medulla oblongata
and the spinal marrow, in a line nearly straight, and seldom tortuous, as
most of the vessels. When they have reached these parts, they termi-
nate in them and are lost, in their substance, as will be mentioned, in
speaking of the structure of these nervous cords.

CXXXVIII. Every nerve is formed of a greater number of filaments,
extremely delicate, and which have two extremities, the one in the brain
and the other from the part in which they terminate, or from which they
originate. Each of these nervous fibres, however minute, is composed
of a membranous tube, which is a production of the pia mater. Within
the parietes of this tube, there are distributed innumerable vessels of
extreme minuteness: it is filled with a whitish marrow, a kind of pulp,
which Reil states he insulated from the small canal containing it, by con-
creting it, by means of the nitric acid, which dissolves the membranous
sheath, and leaves uncovered the medullary pulp forming the essential
part or basis of the nervous filament. The same physiologist discovered,
by a different process, the internal structure of each nervous fibrilla; he
dissolved the whitish or pulpy part, by a long continued solution in an
alkaline ley, and he succeeded thus in separating it from the membranous
tube which enclosed it and which was emptied. The membranous sheath
is of cellular structure, and is remarkable only by its consistence and by
the very considerable number of vessels of all kinds that are distributed
to its parietes; it ceases to cover the nerves near their two extremities,
and protects them only along their course.

Each nervous fibre, thuss formed of two very distinct parts, joins other
fibres of a perfectly similar structure, to form a nervous filament enve-
loped in a common sheath of cellular tissue. These filaments by their
union, form small ramifications, and those progressively larger branches,
and lastly, trunks w? apped in a. common covering of cellular tissue; then
other envelopes to each fasiculus of filaments, and lastly, a sheath to each
individual filament. When nervous cords are of a certain size, veins and
arteries of a pretty considerable calibre, may be seen to insinuate them-
selves between the bundles of fibres of which they are composed; these
vessels then divide, after penetrating among them, and furnish the capil-
lary ramifications which are distributed to the parietes of the sheath
common to each filament. These small vessels, according to Reil, allow
the nervous substance, to exhale into each membranous tube; this, like-
wise, becomes the secretory organ of the medulla with which it is filled.

269

• CXXXIX. The nervous filaments unite, or are separated from one
another, but do not run into each other. The divisions of the nerves are
different from those of the arteries, and their mode of junction does not
admit of being compared to that of the veins. It is, in the first instance,
a mere separation; in the second, an approximation of filaments which had
been separated, and which, though united in common sheaths, have, ne-
nertheless, each a proper covering, are merely in juxta-position and per-
fectly distinct. If that were not the case, one could not say, that each
fibre has one extremity in the brain, and the other in some one point of
the body; nor could one conceive how the impressions which several
sentient extremities receive at once, reach the brain without running
into each other: nor, in what manner the principle of motion could be
directed towards a single muscle receiving its nerves from the same trunk
as the other muscles of the limb.

In general, the nerves divide from each other and unite at an angle
more or less acute, and equally favourable to the circulation of a fluid,
from the circumference to the centre, and from the centre to the circum-
ference.

The structure of the nerves is different according to their situation.
Thus, the medullary fibres of the optic nerve are not furnished with mem-
branous coverings, the pia mater alone furnishing a sheath to the cord
formed by the union of these filaments; the dura mater adds a second
coat to it, on its leaving the skull. This coat, belonging, likewise, to the
whole nerve, is not continued over it, after it has entered the eye-ball,
and is lost in the sclerotica. A minute artery passes through the centre
of the optic nerve, and then dividing, forms a rete mirabile which sup-
ports, the medullary pulp of the retina. The nerves which pass along
osseous canals, as the Vidian nerve of the fifth pair, are not provided
with a cellular covering, and their consistence is always greater than that
of the nerves which are surrounded by soft parts.

CXL. On reaching the brain, the medulla oblongata, or the spinal
marrow, every nervous filament, as was already mentioned, parts with its
membranous covering, which is lost in the pia mater, or immediate co-
vering of these central parts of the brain. The medullary or white part
of the brain is continued into their substance, which may be considered
as principally formed by the assemblage of these nervous extremities
which it is difficult to distinguish in its tissue, from its want of consist-
ence. It has long been known, that the origin of the nerves is not the
spot at which they are detached from the brain, that they sink into the
substance of this viscus, in which their fibres cross each other so that
those on the right pass to the left, and vice versa. Scemmering thought,
that the roots of the nerves, especially of the nerves of the organs of
sense, reached to the prominences in the parietes of the ventricles of the
brain, and that their furthest extremity was moistened by the serosity
which keeps these inward surfaces in contact. It has likewise long been
thought, that the cerebral extremities of the nerves all joined in a fixed
point of the brain, and that to this central point all sensations were car-
ried, and that from it all the determinations producing voluntary motion
arose. But the inquiries of Gall on the structure of the brain and ner-
vous system, have completely overset these various hypotheses.

The spinal marrow and the nerves, in the different animals furnished
with them, are larger in proportion to the brain, according as the animal
is more distant from man in the scale of animation. In carnivorous

270

animals, the prodigious'developement of the muscles required nerves of
motion of a proportionate size; hence, in them, the cerebral mass, com-
pared to the nerves and spinal marrow, is very inconsiderable. It is ob-
served, that there exists the same relation, in men of an athletic dispo-
sition ; the whole nervous power seems employed in moving their large
muscles, and the nerves, though very small in proportion to the rest of
the body, are, however, very large, if compared to the cerebral organ.
In children, in women, and individuals possessed of much sensibility, the
nerves are very large in proportion to the other parts of the body, they
decrease in size and shrink in persons advanced in years; the cellular
tissue which surrounds them, becomes more consistent, adheres to them
more closely; and there exists a certain analogy between the nerves of
old men, enveloped by that yellowish tissue, which makes their dissection
laborious, and the branches of an old tree covered over by a destructive
moss.

As the uses of the nerves cannot be explained independently of those
of the brain, I shall now go on to consider this important viscus.

CXLI. Of the spinal cord, and its functions*. This part of the nervous
system ought no more to be called the spinal prolongation of the ence-
phalon, as it has been by some writers, than it ought to be named the
spinal marrow: both designations are equally erroneous. It is indepen-
dent of the encephalic organ. As the central portion of the nervous
system, it is to be found in many animals which possess no brain, and
its volume is not proportionate to that of this organ. The ox, horse, and
sheep, for example, which have smaller brains than man, have a much
larger spinal cord. It is found in acephalous foetuses, where the brain
never existed. This latter organ appears to be superadded to it, and that
only in the perfect animals, its proportionate size being always in an in-
verse ratio to the spinal cord. This part of the nervous system cannot,
therefore, be considered as a production from the brain, and as formed
by a collection of nerves which successively detach themselves from it.
Its volume does not gradually diminish, owing to the nerves which it
sends off'; and instead of presenting the characters of a cord which gra-
dually decreases in thickness as it advances from the brain, it consists of
a set of knots, bulbs, or separate prominences, equal in number to the
pairs of nerves which arise from it. — Finally, the spinal marrow is formed
in the foetus before- either cerebellum or cerebrum; these organs proceed-
ing from it, and not it from them. About the second month of the foetal
existence, the first epoch at which the brain can be rendered apparent
by the action of alcohol, this organ is uncommonly small in proportion
to the size of the spinal marrow, and arises evidently from a prolonga-
tion of the pyramidal eminences and the corpora oblivaria. The different
parts of the encephalic mass are gradually formed by the. successive de-
velopement of the corpora pyramidalia, and it is only towards the end of
gestation, that the hemispheres are fully formed!-

The special functions that may be assigned to the spinal cord, are dif-
ferent from those performed by the brain. In the spinal marrow resides
the source of all the movements, both voluntary and involuntary, that are
performed by the animal economy: it presides over those of the heart, of

* The whole of this section has been translated from the last French edition of this
work. — Copland.
+ See APPENDIX, Note D D.

271

of all the muscles of the interior life, as well as over those of the loco-
motive apparatus; and while the brain, reserved for the most noble and
most important functions, seems exclusively charged \vilh the operations
of intelligence and thought, the spinal marrow holds under its controul
all the contractile organs, and it is by its influence that all their contrac-
tions are executed*.

Thomas Bartholin had already acknowledged that the brain was more
particularly the organ of sensation, and the spinal marrow that of mo-
tionf. He v/as equally sensible, that the best way of proceeding in the
dissection of the brain, was to advance from the base to the vertex, and
not from the summit to the base, as was the custom until our times.

If we take a view of the graduated scale of the animal creation, says Dr.
Gall, in his Researches of the Nervous System, Sec. the sensible substance,
which is merely gelatinous pulp in the polypus, gradually becomes dis-
posed into nervous filaments and cords hi the more perfect animals. In
order to establish a more extended intercourse with the external world,
Nature has added more complex organs, according as the relation of the
species with the surrounding creation become more numerous : it is thus
that, by the successive addition of new organs, and the perfection of
others, the animal creation is elevated to man himself.

The brain, a simple tubercle added to the anterior extremity of the
spinal marrow, of which it seems to be nothing else than an accessary
part, an appendix, in the insects, because amongst them it is but little
larger than one of their numerous ganglions, becomes more complex and
more perfect in the higher animals : in the fishes it but little exceeds the
spinal cord ; whilst in the mammalia it possesses the same parts as in
man, and is disposed nearly in the same form ; but, in no animal is the
double appearance of diverging and converging fibres better developed
than in him ; in no other animal w the brain properly so called, that is to
say, the superior part of the encephalon, or the hemispheres, possessed
of a greater volume in proportion to the size of the animalj. The brain
proper seems to be the seat of the nobler functions of intelligence, whilst
in the cerebellum the medulla oblongata, and the spinal cord, those fa-
culties and manifestations that are common to us and the lower animals,
appear to reside.

The nervuos system ought not, therefore, to be compared to a tree, the
trunk of whichf represented by the spinal marrow, has its roots in the
brain, and expands its branches through all parts of the body; but ought
rather to be considered as a net-work whose threads communicate with
each other, separate, re-unite, and join several masses or dilatations of
greater or less size: these masses or ganglions ought to be viewed as
being the centres of communication.

The brain should not be considered as a ganglion, or even as a collec-
tion of ganglions, as the common ganglion of the nerves of the cranium,
as some physiologists have done; the nerves which detach themselves
from its base, or from the medulla oblongata, have their origins distinct

* See the above Note i
f " Et id quidem manifestius fit inspicientibus anatomen piscium; ibi enim medulla?
caput et caucla insij.niis est magnitudinis; processus vero medullas ad cerebrum admo-

nocl pisces motu magis quam sen
cortex, ad motum plus medulla i

dum exigunm, cujus rei causa est, quod p'isces motu magis quam sensu utantur, ac sic
ad sensum plus conferat cerebrum vel

See APPENDIX, Note D I).

from its substance. Their volume has no relations to its bulk,,%ut are
proportionate to the perfection of the different senses, in the various spe-
cies of animals; thus, the olfactory nerve, which is very large in the mole,
is small in the eagle, while the optic nerve is on the contrary largely de-
veloped in the latter.

The spinal marrow may be considered as a series of ganglions., com-
municating with each other and with the brain*. These ganglions are
of a size proportionate to that of the nerves which originate from them.
It is owing to this that the spinal marrow is thicker towards the inferior
part of the cervical and dorsal regions, than in other portions of its
length. Can, therefore, the vertebral column be compared to a Galva-
nic pile, of which the spinal cord is the conductor, of which the brain
and the parts of generation form the two extremities^ and constitute, in
a manner, the two poles of this kind of electro-motive apparatus ? Ob-
servation establishes, it may be said, a sort of antagonism between these
two organs. Is there any analogous opposition existing between the ce-
rebral nervous system and that which forms the grand sympathetic
nerves? We have formerly remarked more than once, how ill founded
this attempt at identifying the vital phenomena with those of electricity,
appears to us.

The commnuication of the spinal marrow with the brain is established
by the medium of a double bundle of fibres which, crossing each other,
form the copora pyramidalia, and direct themselves towards the brain,
where we shall find them again when the structure of this viscus comes
under consideration.

CXLII. Of the coverings of the brain. If it be true, that one may judge
of the importance of an organ, by the care which nature has taken to
protect it from external injury, no organ wi^l appear of greater impor-
tance than the brain, for, no one app:e1?P9Ho have been protected with
greater care. The substance of this viscus has so little consistence, that
the slightest injury would have altered its structure, and deranged its
action ; hence it is powerfully guarded by several envelopes, the most
solid of which, is the bony case, in which it is contained.

No part of anatomy is better understood, than that of the many bones
which, by their union, form the different parts of the human head.
Every thing that relates to the place they occupy, to their respective
size, to their projections and depressions to the cavities*whose parietes
they form, every thing that relates to their internal structure, to the dif-
ferent proportions of their component parts, to the aggregation of some
of these substances, in certain points of their extent, has been described
by several modern anatomists, with an accuracy which it would not be
easy to surpass. Several, however, have not sufficiently appreciated the
direct influence of their mode of union on the purposes which they are
destined to fulfil ; no one has insisted sufficiently on the manner in which
they all concur to a principle object ; the preservation of the organs en-
closed within the skull.

Hunauld, in a memoir inserted among those of the Academy of Sciences,
for the year 1730, was the first that endeavoured to account for the ar-
rangement of the articulating surfaces of the bones of the skull. After
laying down a few principles on the theory of arches, and after showing,

See APPENDIX, Note D D.

273

y

that the difference of extent of their concave and convex surfaces, renders
it necessary that the parts of which they are formed, should be shaped
obliquely, he explains the advantages of the sqaamous articulation be-
tween the temporal and parietal bones.

When the arch of the cranium is loaded with a very heavy burthen,
the temporal bones prevent the parietals on which the effort is immedi-
ately applied, from being forced inwardly, or from being separated out-
wardly. Hunauld very aptly compares them to buttresses which are to
the parietal bones of the same use as walls to the arches which they sup-
port.

Bordeu* endeavoured to apply to the bones of the face, the principles
by which Hunauld has been guided in his investigation with regard to
those of the skull. According to Bordeu, the greater part of the bones
of the upper jaw, but particularly the superior maxillary bones, resist the
effort of the lower jaw, which, by acting on the upper dental arch, has a
perpetual tendency to force upward, or to separate outwardly, the bones
in which the teeth of that ja\v arc inserted. As the greatest stress of the
effort determines them upward, it is, likewise, in that direction, that the
bones of the upper jaw rest more powerfully on those of the skull. The
author concludes this very ingenious memoir, by proposing to physiolo-
gists, the solution of the following problem, " When a man supports a
great weight on his head, and holds at the same time any thing very
firmly between his teeth, which is the bone of the head that is most
acted upon ; which supports the weight cf the whole machine ?"

The body of the sphenoid, and especially the posterior half, appears
to me to be the central point on which the united efforts of the bones of
the skull and of the face act, in the case supposed by Bordeu.

The sphenoid is connected with all the other bones of the skull ; it is
immediately connected with several of the bones of the face, as with the
malar bones, with the palatine bones, with the vomer, and sometimes,
with the superior maxillary bones. These bones of the face, in the case
in question, alone support the lower jaw against the upper. The ethmoid
bone, the ossa unguis, and the inferior turbinated bones, are thin and frail,
and serve merely to form the nasal fossae, of which they increase the
windings, and do not deserve to be' attendee^* to in this investigation.
The vomer may, it is true, communicate to the ethmoid, in an inferior
degree, a part of the effort; for, the anterior part of its upper edge is
articulated with the perpendicular lanffclla of that bone ; but this quan-
tity is very small, as the vomer is thin and transmits it almost wholly,
to the body of the sphenoid, with the lower face of which it is articu-
lated.

The effort exerted on the bones of the upper jaw, is transmitted, by
means of the nasal processes of the upper maxillary bones, by the orbital*-
and zygomatic processes of the malar bones, and by the upper edge of the
palate bones and of the vomer, to the frontal, to the temporal, and sphenoi-
dal bones.

If we wish to determine what becomes of the greater part of the effort
transmitted to the frontal bones by the maxillary and malar bones, we may
observe in the first place, that it is articulated with the sphenoid bone, by

* Academe des Sciences, Memoircs presentes par les savans strangers. Tome EL

2M

274

tlie whole of its lower edge which is bevelled at its inner part, so that it
is covered by the alse minores of the os sphenoides, which is shaped ob-
liquely at the outer part of the bone. The frontal bone is articulated, be-
sides, with the lateral and inferior parts of its upper edge. The remain-
der of this upper part is united to the anterior edge of the parietal bones,
which by means of a slope, in a different direction, rest on the middle
part of this edge, while the frontal bone is applied to them laterally.

This bone which the effort tends to force upward and backward, can-
not yield to this double impulse, for, on the one hand, its mode of articu-
lation with the anterior edge of the alae minores of the sphenoidal bone,
and the internal -part of the anterior edge of the parietal bones, resist
this tendency upward, while the resistance from the latter, prevents them
from being forced backward. That share of the effort which affects the
parietal bones, follows the curved lines described by these bones, and ex-
tends along that formed by the occipital, and thus reaches the posterior
face of the body of the sphenoid bone.

The portion directly transmitted by the anterior and inferior face of
this bone, by the ossa palati and by the vomer, is considerable and pro-
portioned to their thinness. The anterior half of the body of the sphe-
noid bone, hollowed by the sphenoidal sinus, would have been incapable
of supporting greater pressure. Lastly, the situation of the body, placed
between the dental arches, in front of the place occupied by the ossa pa-
lati, explains why this transmission is chiefly effected by the upper maxil-
lary bones.

The above is the manner in which the effort exerted from below up-
ward, by the lower on the upper jaw, is carried to the anterior, posterior,
and inferior faces of the body of the sphenoid bone.

The temporal bones which are affected by it, in a very slight degree,
by means of the zygomatic processes of the malar bones, support the
greater weight of the effort acting from above downward, or from the
arch of the skull towards its base. The weight laid on the head, tends
to depress or to separate the parietal bones, which resist the pressure, in
consequence of the support afforded them by the temporals. These trans-
mit the effort to the lateral and posterior parts of the body of the sphe-
noid, by means of the alae majores of that bone, which are articulated, along
the whole extent of their external edge, and along the posterior fourth of
their internal edge, with the temporals. Besides, the upper extremity of
the alae majores is sloped, on the inner part of the bone, that it may be ar-
ticulated with the anterior and inferior angles of the parietal bones, and
answer the same purpose to them as the squamous portion of the tem-
porals.

The lateral and posterior parts of the body of the sphenoid support,
therefore, almost the whole effort of the pressure applied to the parietal
bones. It is communicated to them by the ate majores, which receive
it themselves, either directly at the anterior and inferior angles of this
bone, or through the medium of the temporals. The small portion of
the effort transmitted by the latter to the occipital, follows the curved
line of this bone, and is felt on the posterior face of the body of the sphe-
noid.

To the effort resulting from the pressure exerted by the body on the
summit of the head, one should add that occasioned by the contraction of
the muscles which elevate the lower jaw. These tend to depress the tem-
poral, the malar and the sphenoid bones, and in this action, they employ-

•SL power equal to that by which they raise the lower jaw, and press it firm-
ly against the upper.

The effort exerted from the arch to the base of the skull depends there-
fore, on two very different causes: the portion resulting from the action
of the elevators of the lower jaw, is equal to the effort exerted from be-
low upward, by this bone. After what has been stated, it would be use-
less to say any thing further of the manner in which the effort is trans-
mitted : we may merely observe, that the least powerful of these muscles,
the internal pterygoid, tends to draw the sphenoid downward, and pre-
vents this bone, fixed like a wedge with its base turned upward, from
being disengaged by the effort applied to it, by the bones between which
it is situated.

The posterior, anterior, inferior and lateral faces of the sphenoid bone,
support, therefore, the whole effort of the bones of the skull and face, on
one another, when the top of the head being loaded with a heavy burden,
one presses, at the same time, something very firmly between the dental
arches.

The anterior part of the body of the bone, containing the sphenoidal
sinus, is thin and very frail ; the posterior part, corresponding to the celia
turcica, is alone capable of resisting the effort which, I believe, it is des-
tined to sustain*: hence, it is at this point, that ossification begins, and
this confirms the observation of Kerkringius that the spot at which bones
begin to ossify, is that on which they have to bear the greatest effbrt;
hence the alae majores, by means of which the greatest part of the efforts
which the body of the sphenoid has to support, arise from the lateral part
of its posterior half, by an origin of considerable size, and which is fur-
ther increased by the base of the pterygoid processes which arise from
its lower part.

I have, in this inquiry, purposely avoided mentioning the support which
the head receives from the vertebral column, and which, in the case un-
der consideration, is of use merely in preventing it from yielding to the
law of gravitation. If the bones of the skull and of the face had passed,
during the effort which they sustain, on the circumference of the fora-
men magnum; this aperture would have been incapable of increasing its
dimensions, and this would have been attended with the most serious in-
conveniences.

The name given by the ancients to the braje whose principal use has
just been explained, is composed of spheno^which means a wedge, and
eidos, which signifies resemblance, and would lead one to think, that they
were not ignorant of its uses. From its situation, at the middle and in-
ferior part of the skull, and from its various connexions with the bones
which form this osseous case, it is to them of the same use as the key-
stone of arches, with regard to the different parts of which they are
formed. The numerous connexions required for this purpose, account

* The sphenoidal sinus is prolonged, it is true, into this posterior part of the body of
the bone, in persons considerably advanced in years; but the parietes of this portion of
its cavity are of considerable thickness. The anterior part of the basilary process of
the occipital bone, is ihen firmly united to the sphenoid, and maybe considered as form-
ing a part of that bone, from which it cannot be detached. The cranium of an old man,
in this respect, resembles that of several quadrupeds, in which the union of the sphe-
noid to the occipital bone takes place so early, thatthese two bones might well be con-
sidered as forming but one.

276

for its strange and irregular form and for the different shapes of its arti-
cular surfaces and the great number of its projections, which render the
demonstration of this bone so complicated, and a knowledge of it so
difficult.

It is more advantageous, withregard to the brain, that the skull should
be formed of several bones, than if it had consisted of a single bone. It
resists, more effectually, the blows it receives, their effect being lessened,
in passing from one bone to the other, and being interrupted, in the ob-
scure motions which they may experience at their sutures; its rounded
form increases, likewise, its power of resistance. This force would be
equal, in every point of the parietes of the cranium, if the form of that
cavity were completely spherical, and if the thickness of its parietes were,
in every part of it, the same. In that case, no fractures by contre coup
could occur, a kind of lesson occasioned by the unequal resistance of the
bones of the head, to the force applied to their surface. The pericrani-
um, the hairy scalp, the muscles which cover it, and the great quantity of
hair on its surface, serve, besides, to defend the brain, and are well cal-
culated to break the force of blows applied to the cranium.

In addition to this hard and unyielding case, there lies over the brain,
a treble membranous covering, formed by the dura mater, which owes
its names to the erroneous opinion according to which it was supposed to
form all the other membranes of the body; it is further covered by the
tunica arachnoidea, so called from the extreme minuteness of its tissue,
and by the pia mater which adheres firmly to the substance of the brain.

The dura mater lines, not only the inside of the skull and of the verte-
bral canal, which may be considered as a prolongation of it, but, like-
wise, penetrates between the different parts of the cerebral mass, sup-
ports them in the different positions of the head, and prevents mutual
compression. Thus, the greatest of its folds, the falx, stretched between
the crista galli of the ethmoid bone, and the inner protuberance of the
occipital bone, prevents the two hemispheres of the brain, between which
it lies, from compressing each other, when the body is on the side, and
maintains, on the other hand, the tentoriutn cerebelli in the state of ten-
sion necessary to enable it to support the weight of the posterior lobes of
the brain. This fold of dura mater is of a semi-circular form, separates the
portion of the skull which contains the brain, from that in which the cere-
bellum is situated. It is keot in a state of tension by the falx cerebri, on
which it also exerts the sjfce action : it does not present a horizontal
plane to the portion of brain which lies upon it, but one that slopes, in
every direction, towards the parietes of the skull, to which it transmits
most of the weight which it has to support. The tentorium cerebelli,
which thus divides the internal cavity of the skull into two parts of unequal
dimensions, is bony in some animals that move by bounding and with
rapid action; this is the case with the cat, which can, without being
stunned, take leaps from a considerable height. By means of this com-
plete partition, the two portions of the brain are prevented from passing
on each other, in the violent concussions which they experience.

The tunica arachnoides, according to Bonn*, who was thoroughly ac-
.quainted with its structure, and who has given a very beautiful plate of
it, is the secretory organ of the serum which moistens the internal sur-

Dissertatia de continuation} bits msmbranartim. Lug-dun. 4° Bat. 1763.

277

face of the dura mater, a fibrous membrane which serves as a periosteum
to the bones it lines*.

CXLII1. Of the size of the brain. Of all animals, man has the most
capacious skull, in proportion to his face, and, as the bulk of the brain
is always of a size t proportioned to that of the osseous case which con-
tains it, the brain is also most bulky in man. This difference of size be-
tween the cranium and face, may be taken as the measure of the human
understanding and of the instinct of the lower animals ; the stupidity and
ferocity of the latter are greater, according as the proportions of these
two parts of their skull, vary from those of the human head.

To express this difference of size, Camper imagined a vertical line
drawn from the forehead to the chin, and perpendicular to another drawn
in the direction of the base of the skull. He has called the first of these
lines facia!, the second, palatine or mental. It is easy to understand, that,
as the projection of the forehead is determined by the size of the skull,
the larger it is, the more the angle at which the facial line meets that
from the base of the skull must be obtuse. In a well-formed European
head, the facial line meets the palatine at an angle nearly straight, (of
between eighty and ninety degrees.) When the angle is quite straight,
and the line which measures the height of the face is completely vertical,
the head is of the most beautiful form possible, it approaches most to
that conventional degree of perfection which is termed ideal beauty. If
the facial line slopes backward, it forms with the palatine line, an an-
gle more or less acute, and projecting forward, the inclination increases,
and the sinus of the angle is shorter; if, from man, we pass to monkeys,
then to quadrupeds, to birds, reptiles, and fishes, we find this line slope
more and more, and, at last, become almost parallel to the mental, as in
reptiles and in fishes, with flat heads. If, on the contrary, we ascend
from man to the gods, whose images have been transmitted to us by the
ancients, we find the facial line to incline in a different direction, the an-
gle then enlarges and becomes more or less obtuse. From this inclina-
tion forward of the facial line, there results an air of grandeur and ma-
jesty, a projecting forehead, indicating a voluminous brain and a divine
intellect}.

To obtain with precision, by this means, the respective dimensions of
the skull and face, one must measure, not only the outside, but, likewise,
draw the tangents on the internal surfaces, after dividing the head verti-
cally. There are, in fact, animals, in which the sinuses of the frontal
bone are so large, that a considerable portion of the parietes of the

* Analagous to the serous membranes which line the cavities of the body, the arach-
noid is a shut sac, whose internal surface is every where in contact with itself, while its
external surface adheres to the two other meninges. The serosity which exudes from
the internal surface of the arachnoid differs from that which escapes from the other
serous membranes, owing to the almost entire absence of albumen from the former.
The exhalation that takes place from this membrane appears to be the source of a more
limpid and dilute effusion, even in disease, than that which is observed in the other
serous cavities. — Copland.

•J- This should be ruialin'ed. In many animals the cavity of the skull is small, while
the osseous case appears large ; this great extent of bone is for the origin of the power-
ful muscles necessary to the seizing and comminution of their food. — Godman.

$ It should not be forgotten, that this is true only when the tbcial angle does not much
exceed 90P. Foreheads projecting more than this, are most frequently those of idiots
or hydrocephalic persons. — Godman.

278

skull is protruded by their cells. Thus, in the dog, in the elephant,
in the owl, Sec. the apparent size of the skull exceeds much its real
capacity*.

The relative size of the head, and consequently the proportionate bulk
of the brain, is inconsiderable in very tall and muscular subjects : this fact
will be confirmed by observing1 the proportions of antique statues. In all
those which represent heroes or athlets gifted with a prodigious bodily-
power, the head is very small, in proportion to the rest of the body. In
the statues of Hercules, the head scarcely equals in size the top of the
shoulder. The statues alone of the King of the Gods, present the singu-
lar combination of an enormous head, resting on limbs of a proportionate
size, but the Greek artists have transgressed the laws of Nature, only in
favour of the God that rules over her, as if a vast brain had been neces-
sary to one whose intellect carries him, at a glance, over the universe.
The relative small dimensions of the head, in athlets, depend on this cir-
cumstance, that in such men, the excessive developement of the organs
of motion, gives to the body, and especially to the limbs, an enormous
size, while the head covered by few muscles, remains very small. Scem-
mering has stated, that the head in women is larger than in men, and
that their brain is heavier; but it must be recollected, that this great
anatomist obtained this result, by examining two bodies, male and fe-
male, of the same length. Now, the absolute size being the same, the
proportionate magnitude was not so, and he was wrong in comparing the
head, the skull, and brain of a very tall woman, to that of a very short
man.

It has long been thought, that there exists a connexion between the
bulk of the cerebral mass and the energy of the intellectual faculties. It
has been thought, that, in general, men whose minds are most capacious,
whose genius is most capable of bold conceptions, have a large head sup-
ported on a short neck. The exceptions to this general rule have been
so numerous, that many have doubted its truth; should it then be abso-
lutely rejected, and will it be allowed to be wholly without foundation,
when we consider that man, the only rational being out of so great a
number, and some of which bear to him a considerable resemblance both
of organization and structure, is, likewise the only animal in which the
brain, properly so called, is largest in proportion to the cerebellum, to the
spinal marrow, to the nerves, and to the other parts of the body ? Why-
may it not be with the brain, as with the other organs, which fulfil their
functions the better, from being more completely developed ? It should
be recollected, in this comparison of the brain and of the intellectual pow-
ers, that several causes may give to this viscus an unnatural degree of
enlargement. Thus, in subjects of aleucophlegmatic temperament, the
tardy ossification of the bones of the skull, causes the brain, gorged with
aqueous fluids, to acquire a considerable size, without its containing a
greater quantity of real medullary substance. Hence it is observed, that
men of this temperament are, most frequently, unfit for mental exertion,
and rarely succeed in undertakings that require activity and perse-
verancef.

* Se APPENDIX, Note D D.

f See, in the article on Temperaments, an account of the influence of the physical
organization on the moral disposition and on the intellectual faculties.

CXLIV. Structure of the cerebral mass. What we know of the brain,
serves only to show us that we are ignorant of much more. All that we
know of it consists of notions tolerably exact of its external conformation,
its colour, its density, and of the different substances that enter into its
composition; but the knowledge of its intimate structure is yet a rays--
tery, which will not be so soon unveiled to us. The brain, properly so call-
ed, is divided by a longitudinal furrow, into two lobes of equal bulk —
Gunzius, however, imagined that he found the right lobe, or hemisphere,
a little larger than the left; but even were this fact as certain as it is
doubtful, we could not thereby explain the predominant force of the right
side of the body, since the nerves which are distributed to this side, rise
from the left lobe of the brain, in the substance of which all the roots of
these cords cross. This fact of the crossing of the nerves, at their origin,
is proved by a number of pathalogical observations, in which the injury
of a lobe is always found to bring on paralysis, convulsion, or any other
symptomatic affection, on the opposite side of the body. Unless you
choose to explain this phenomena by admitting a necessary equilibrium
in the action of the two lobes; an equilibrium, the disturbance of which
is the the occasion that the sound lobe, acting with more force, com-
presses the origin of the nerves on its side, and determines paralysis. —
Might the%want of judgment, the unevenness of humour and character,
depend on the want of harmony between the two corresponding halves of
the cerebral mass ?

In order to disclose, better than had been before done, the structure of
the brain, M. Gall begins his dissection at the lower part, examining, in
the first place, the anterior part of the prolongation, known under the
name of the cauda of the medulla oblongata, he finds the two pyramidical
eminences. If you part the two edges of the median line, below the fur-
row which separates the two pyramids, you see distinctly the crossing of
three or four cords or fasciculi of nerves, which, consisting of many fila-
ments, tend obliquely from right to left, and vice versa*'. This crossing
of nervous fibres, which is not found in any other part of the brain, had
been observed by several anatomists. It is not known how it came to be
forgotten, so that the mobt exact and latest among them, Boyer, for in-
stance, says that the crossing of the nerves cannot lie proved by anatomy.
These nervous cords, traced upward, enlarge, strengthen, and forming
pyramidical eminences, ascend towards the tuber annulare. Having
reached the ganglion, the fibres strike into it, and are lost in a mass of
pulpy or greyish substance, of the same nature as that, which, under the
the name of cortical substance, covers the two lobes of the brain. This
greyish pulp, distributed in various parts, may be considered, agreeably
to the views of M. Gall, who calls it the matrix of the nerves, as the
source from which the medullary fibres take their origin. These ascend-
ing fibres cross other transverse fibres, which, on either side, proceed
from the crura of the cerebellum ; enlarged and multiplied by means of
their passage through the grey substance which is found in the tuber an-
nulare; they rise from it, at its upper part, in two fasciculi which cdfib

* While dissecting the brain, in 1823, after the manner described by J)r. Gall, lob-
served a beautiful and well marked semicircle of fibres, descending1 from the upper part
of the corpora olivaria, on their outside, and after nearly reaching- their inferior points,
rising and being continued over the surface of the corpora pyramidalia, until it reached
the edge of the tuber annulare. — Godman,

pose nearly the whole of the crura cerebri. The interior of these crura,
contains a certain quantity of grey substance, which is what nourishes
the nervous fibre*. On reaching the ventricles, these peduncles, or rather
the two fasciculi which form them, meet with large ganglions, full of
grey substance ; these have long been called thalami optici, though they
do not give origin to the optic nerves. There the fibres are sensibly en-
larged : and they pass from the thalami optici into new ganglions.
These are the corpora striata, and the striae which are apparent on cut-
ting these pyriform masses of grey substance, are only the same fibres,
which, enlarged, multiplied, and radiated, spread out in the manner of
a fan, towards the lobes of the brain, where, after forming by their ex-
pansion, a whitish and fibrous substance, they terminate at the outer
part of that viscus, forming its convolutions, all covered with the sub-
stance in which are terminated, in like manner, the extremities of the
diverging fibres. From this grey substance, proceed converging fibres
tending from all parts of the periphery to the centre of the brain, where
they unite to form the different commissures, the corpus callosum, and
other productions, destined to facilitate the communication of the two
hemispheres!.

The exterior of the brain may, therefore, be considered as a vast ner-
vous membrane, formed by the grey substance. To form a clue concep-
tion of its extent, it must be understood, that the convolutions of the
brain, are a sort of duplicatures, susceptible of extension by the unfold-
ing of two contiguous medullary lamina, which form its base. The exte-
rior surface of the brain, by means of this unfolding, offers them some
relation to the skin, a vast nervous expanse every where covered by a
sort of pulpy substance, known by the name of the rete mucosum of
Malphigi. M. Gall compares this cutaneous pulp, to the cineritious sub-
stance which forms the outer part of the brain, and, I must confess, it is
not every one that will admit the analogy. However, true it is, that the
brain consists, principally, of a mass of ganglions, that it produces nei-
ther the elongated medulla, nor the spinal marrow, that this last may be
considered as a series of ganglions, united together that the vertebral nerves
arise from the greyish pulp of which the spinal marrow is full, as is best
seen in animals without a brain, but not the less provided with a spinal
marrow, or series of ganglions, from which the nerves arise. The gan-
glions, or rather the grey substance which they always show, produce
the nervous fibres, and thicken the nervous cords that pass through
them.

That is the only use that can be assigned to these parts of the nervous
system ; for, if they were meant to withdraw from the dominion of the
will, the parts in which they are found, why do not the ganglions of the
vertebral nerves fulfil the same function ? All these nerves communicate
by the reciprocal anastamoses. These communications, in man, are
equivalent to a real continuity. In truth, the brain acts upon the nerves
that proceed from the spinal marrow, is if this were one of its produc-
4|ns, and all the nervous fibres, spread through the different organs, had
an extremity terminating in this viscus.

* This means simply that the cineritious substance is found where the fibrous matter
is increased, or ganglia are formed. As to its nourishing the fibrous structure, it is a
mere assumption, or begging the question.-*- Godman.

f See APPENDIX, Note D D. ^

.

281

One thing well worthy of attention, and on which no anatomist has
dwelt, is that the brain of the foetus, and of the child just born, appears
to consist almost entirely, of a cineritious pulp, to such a degree that the
medullary substance is difficult to perceive in it. Would it be absurd to
believe, that the medullary part of the brain does not take its perfect or-
ganization till after birth, by the developement of the fasciculi of medul-
lary fibres, in the midst of these masses of cineritious substance, which
must be considered as the common source from which the nerves have
their origin, or, to use the language of Gall, as the uterus which gives
them birth. The almost total inactivity, the passive state of the brain,
in the foetus, makes unnecessary there the existence of the medullary ap-
paratus, to which the most important operations of intelligence seem en-
trusted. Its first rudiments are found in the foetus at its full time. That
fibro medullary apparatus will be strengthened by the exercise of thought,
as the muscles are seen to enlarge and perfect their growth, by the effect
of muscular action.

CXLV. Circulation of the brain. I have said that the blood, in its
circular course, does not traverse the different parts of the body with uni-
form velocity; that there are partial circulations in the midst of the ge-
neral circulation. In no organ are the laws, to which this function is
subjected, more remarkably modified than in the brain. There is none
which receives, in proportion to its bulk, larger arteries and more in num-
ber. The internal carotid and vertebral arteries, as we may satisfy our-
selves from the calculations ot tialler, carry thither a great portion of the
whole quantity of blood that flows along the aorta ; (from a third to the
half.)

The blood which goes to the brain, said Boerhaave, is more aerated
than that which is distributed to the other parts : the observation is not
without foundation. Though the blood which the contractions of the left
ventricle send Into the vessels, arising from the arch of the aorta, does
not undergo, at the place of this curvature, a mechanical separation car-
rying its lighter parts towards the head; it is not less true, that this
blood, just passing from the contact of the air in the lungs, possesses,
in the highest degree, all the peculiar qualities of arterial blood. So
great a quantity of light, red, frothy blood, impregnated with caloric
and oxygen, coming upon the brain, with all the force it has received
from the action of the heart, would unavoidably have deranged its soft
and delicate structure, if nature had not multiplied precautions to weak-
en its impulse.

The fluid compelled to ascend against its own weight, loses, from that
alone, a part of its motion. The vertical column must strike against the
angular curvature which the internal carotid takes in its passage along
the osseous canal of the petrous portion of the temporal bone, and as this
curvature, supported by hard parts, cannot straighten itself, the column
of blood is violently broken and turned out of its first direction, with con-
siderable loss of velocity.

The artery immersed in the blood of the cavernous sinus, as it comes
out from the carotid canal, is very easily dilated. Finally, the branches
into which it parts, on reaching the base of the brain, have coats exceed-
ingly thin, and so weak that they collapse, when they are empty, like
those of the veins. This weakness of the cerebral arteries, explains their
frequent ruptures, when the heart sends the blood into them too violent-
ly ; and it is thus, that the most part of sanguineous apoplexies are oc-

282

casioned, many of which, however, take effect without rupture, and by
the mere transudation of blood through the coats of the arteries. These
vessels, like the branches arising from their divisions, are lodged in the
depressions with which the base of the brain is furrowed, and do not en-
ter its substance, till they are reduced to a state of extreme tenuity, by
the further divisions they undergo, in the tissue of the pia mater.

Notwithstanding the proximity of the brain to the heart, the blood
reaches it, then, with an exceedingly slackened motion : it returns, on
the contrary, with a motion progressively accelerated. The position of
the veins at the upper part of the brain, between its convex surface and
the hollow of the skull, causes these vessels, gently compressed by the
alternate motions of rising and falling of the cerebral mass, to disgorge
their contents readily into the membranous reservoirs of the dura mater,
known by the name of sinuses These, all communicating together, of-
fer to this fluid a sufficiently large receptacle, from which it passes into
the great jugular vein, which is to carry it again into the general course
of the circulation. Not only is the calibre of this vein considerable, but
its coats too, of little thickness, are extensible : so much so, that it ac-
quires by injection, a calibre superior to that of the venae cava. The
flowing of the blood is favoured by its own weight, which makes a retro-
grade course very difficult*. — Thus, to sum up all that is peculiar in the
cerebral circulation, the brain receives, in great quantity, a blood abound-
ing in oxygen ; the fluid finds, in its course thither, many obstacles which
impede and slacken its impulse, whilst all uu the cuntrary, favours its re-
turn, and prevents venous congestion!. Let me observe, to conclude
what I have to say on the circulation of the brain, that of the eye is near-
ly allied to it, since the ophthalmic artery is given out by the internal ca-
rotid, and the ophthalmic vein empties itself into the cavernous sinus of
the dura mater. Accordingly, the redness of the conjunctiva, the promi-
nence, the brightness, the moistness of the eyes, indicate a stronger de-
termination of the blood towards the brain. Thus the eyes are animat-
ed at the approach of apoplexy, in the transport of a burning fever, du-
ring delirium, a dangerous symptom of malignant or ataxic fevers. On
this connexion of the vessels of the eye and brain, depends the lividity of
the conjunctiva, whose veins, injected with a dark coloured blood, indi-
cate the fullness of the brain in the generality of cases of suffocation.

CXLVI. Of the connexion betiueen the action of the brain and that of tlie
heart. It is possible, as was done by Galen, to tie both carotids, in a liv-
ing animal, without his appearing sensibly affected by it ; but if, as has
never yet been done, both the vertebral arteries are tied, the animal drops
instantly and dies, at the end of a few seconds. To perform this experi-
ment, it is necessary, after tying the carotid arteries of a dog, to remove
the soft parts which cover the side of the neck, then with needles, bent in
a semi-circular form, passed into the flesh along the sides of the articu-
lation of the cervical vertebrae, to apply ligatures to the arteries which

* In preventing this reflux, there is no use of valves, which the jugular vein is entire-
ly without. It is sufficiently prevented, hy the direction in which the blood Hows, and
the extensibility of its coats. This great size which the vein can acquire, would have
made useless the valvular folds, insufficient to stop the canal, in that great augmenta-
tion of its dimensions. — Author's Note.

t The transverse anastomoses of the arteries, at the base of the brain, are very prop-
er for distributing the blood, in equal quantity, to all parts of this viscus, — Copland

283

ascend along their transverse processes. The same effect, viz. the speedy
death of the animal is produced by tying the ascending aorta in an herbi-
vorous quadruped.

These experiments, which have been repeated a number of times, de-
cidedly prove the necessity of the action of the heart on the brain, in pre-
serving life. But how does this action operate ? Is it merely mechanical?
Does it consist solely in the gentle pressure which the arteries of the
brain exert on the substance oif this viscus, or is it merely, to the inter-
cepted arterial blood which the contractions of the heart determine to-
wards the brain, that death is to be attributed ? The latter opinion seems
to me the most probable, for, if, the moment the vertebrals have been
tied, the carotids are laid open, and the pipe of a syringe adapted to them,
and any fluid whatever is then injected with a moderate degree of force,
and at nearlv the s*ame intervals as those of the circulation, the animal
will not be restored to life.

The heart and brain are, therefore, united to each other by the strict-
est connexion, the continual access of the blood flowing along the ar-
teries of the head, is, therefore, absolutely necessary to the preserva-
tion of life ; if intercepted, for one moment, the animal is infallibly de-
stroyed.

The energy of the brain appears, in general, to bear a relation to the
quantity of arterial blood which it receives. I know a literary man, who,
in the ardour of composition, exhibits all the symptoms of a kind of brain
fever. His face becomes red and animated, his eyes sparkling ; the ca-
rotids pulsate violently ; the jugular veins are swollen, every thing indi-
cates that the blood is carried to the brain with an impetus, and in a
quantity proportioned to its degree of excitement. It is, indeed, only du-
ring this kind of erection of the cerebral organ, that his ideas flow with-
out effort, and that his fruitful imagination traces, at pleasure, the most
beautiful descriptions. Nothing is so favourable to this condition as re-
maining long in a recumbent posture : in this horizontal posture, the de-
termination of the fluids towards the head is the more easy, as the limbs,
which are perfectly quiescent, do not divert its course. He can bring on
this state by fixing his attention steadfastly on one object. May not the
brain, which is the seat of the intellectual action, be considered as a cen-
tre of fluxion ; and may not the stimulus of the mind be compared, as to
its effects, to any other stimulus, chemical or mechanical* ?

A young man of a sanguineous temperament, subject to inflammatory fe-
vers which always terminate by a profuse bleeding at the nose, experien-
ces, during the febrile paroxysms, a remarkable increase of his intellec-
tual powers and of the activity of his imagination. Authors had already
observed, that in certain febrile affections, patients of very ordinary pow-
ers of mind, would sometimes rise to ideas, which in a state of health,
would have exceeded the limits of their conception. May we not ad-
duce these facts in opposition to the theory of a celebrated physician,

•

* The inequality of the distribution of the blood, attributable to the peculiar action
of food &c. on the stomach and nerves, immediately connected with the great vessels
going to the brain, is peculiarly worthy of the attention of physiologists and pathologists.
In a paper, published in the 3d volume of the Philadelphia Journal, an attempt is mad6
"to show the relation of nerves producing1 some of the most remarkable sympathetic
connexions. — Godmav .

,

who considers a diminution of the energy of the brain to be the essential
character of fever ?

It is well known that the difference of the length of the neck, and, con-
sequently, the greater or lesser degree of vicinity of the heart and brain,
give a tolerable just measure of the intellect of man, and of the instinct of
the lower animals ; the disproportionate length of the neck has ever been
considered as the emblem of stupidity.

In the actual state of our knowledge, is it possible to determine in what
manner arterial blood acts on the brain ? Are oxygen or caloric, of which
it is the vehicle, separated from it by|this viscus, so as to become the prin-
ciple of sensation and emotion, or do they merely preserve it in the de-
gree of consistence necessary to the exercise of its functions ? What is to
be thought of the opinion of those chemists who consider the brain, as a
mere albuminous mass, concreted by oxygen, and of a consistence vary-
ing in different persons, according to the age, the sex, or the state of
health or disease ? Any answer that one might give to these premature
questions, would be but a simple conjecture to which it would be diffi-
cult to give any degree of probability*.

CXLVII. Of the theory of syncope. If we consider the action of the
heart on the brain, we are naturally led to admit its necessity to the main-
tenance of life, and to deduce from its momentary suspension, the theo-
ry of syncope. Several authors have attempted to explain the manner in
which their proximate cause operates, but as not one of them has gone
upon facts ascertained by experience, their explanations do not at all
agree with what is learnt from observing the phenomena of these dis-
eases.

To satisfy one's self, that the momentary cessation of the action of the
heart and the brain, is the immediate cause of syncope, one need but
read, with attention, the chapter which Cullen, in his work on the prac-

* The connexion which exists between the functions of the heart and those of the
brain, are not only manifest in their healthy relations, but also in their disordered ac-
tions. PORTAL, BRICHETEAU and TESTA had pointed out this connexion in the diseases
of these organs, and more recently Dr. CRAISIE has contended for its importance, al-
though some contemporary puthologists have denied its existence. This pathologist,
after stating his experience on the subject, draws the following inferences from it : —

" 1st. It is quite obvious, that several maladies of the heart, such as ossification of the
left side, or of the artery connected with it ; ossification of the mitral valve ; of the semi-
lunar valves ; ossification of the apertures either auriculo-ventricular, or aortic, have a
tendency to terminate in extravasation within the cranium, producing apoplexy, paraly-
sis, or a comatose state terminating in death.

"2d. It is by no means difficult to see how these effects in the cerebral organ result
from an irregular and disordered action of the heart. The difficulty which the blood
experiences in passing either, 1st. through the auriculo-ventricular opening ; 2d. the
aortic orifice ; 3d. along the aorta, necessarily produces a stagnation and congestion ;
1st. in the pulmonary veins ; 2d. in the pulmonary artery ; 3d. in the right side of the
heart. The effect of this is to retardpr impede very remarkably the return of the blood
from the cerebral veins, and consecutively either to distend them, to rupture them, or
to occasion an effusion of the serous part of the blood, as we find in other examples of
obsti-ucted venous circulation." — (Edin. Med. Journ. JYo. 74.) — Dr. Craigie has, how-
ever, omitted to mention the influence of active enlargement of the left side of the
heart in causing apoplexy, owing to the increased impulse or determination of blood
which is thus produced, and to which the brain is most obnoxious. This and every oth-
er form of connexion of disease of the heart with apoplexy can only be viewed as occa-
sional occurrences, the former states being by no means necessarily followed by the lat-
ter. — Copland.

285

tice of physic, has devoted to the consideration of this kind of affection.
It will be readily understood, that their occasional causes, the varieties
of which determine their different-kinds, exist in the heart or great blood-,
vessels, or act on the epigastric centre, and affect the brain only in a se-
condary manner. Thus, the kinds of syncope occasioned by aneurismal
dilatations of the hear* and great vessels, by polypous concretions formed
in these passages, by ossification of their parietes or of their valves, evi-
dently depend on the extreme debility, or on the entire cessation of the
action of the heart and arteries. Their parietes, ossified, dilated, ad-
hering to the neighbouring parts, or compressed by any fluid whatever,
no longer act on the blood with sufficient force, or else this fluid is in-
terrupted in its progress by some obstacle within its canal, as a polypous
concretion, an ossified and immoveable valve. Cullen, very justly, termed
these, idopathic or cardiac syncopes.

To the above may be added plethoric syncope, depending on a con-
gestion of blood in the cavities of the heart: the contractions of this or-
gan become more frequent, it struggles to part with this excess of blood,
which is injurious to the performance of its functions: but to this un-
usual excitement, by which the contractility of its fibres is exhausted,
there succeeds a kind of paralysis necessarily accompanied by syncope.

One may, likewise, include the fainting attending copious blood-let-
ting ; the rapid detraction of a certain quantity of the vivifying principle,
deprives the heart of the stimulus necessary to keep up its action. The
same effect is produced by drawing off the water contained in the abdo-
men, in ascites: a considerable number of vessels cea§e to be compressed;
the blood, which they before refused to transmit, is sent to them in pro-
fusion; the quantity sent to the brain by the heart is lessened, in the same
proportion, and becomes insufficient for its excitement. Among the syn-
copes, called idiophatic, one may enumerate those occurring in the last
stage of the scurvy, the principal character of which is, an excessive de-
bility of the muscles employed in the vital functions, and in voluntary
motion; lastly, we may add asphyxia from strangulation, from drowning,
and from the gases unfit for respiration ; affections in which the blood
being deprived of the principle which enables it to determine the con-
tractions of the heart, the circulation becomes interrupted. If the blood
loses, by slow degrees, its stimulating qualities, the action of the heart
gradually weakened, impels towards the brain a blood which, by its
qualities, partakes of the nature of venous blood, and which, like it,
cannot preserve the natural economy of the brain. It was thought, that
by injecting a few bubbles of air into the jugular vein of a do.-, one might
occasion in the animal immediate syncope, and that it was even su.ncient
to deprive it of life; but the late experiments of Nysten have proved,
that the atmospherical air produces these bad effects, only when injected
in a quantity sufficient to distend, in excess, the cavities of the heart, or
when by being injected into the arteries it compresses the brain. When
injected only in a small quantity, the gas dissolved in the venous blood,
is conveyed along with it to the lungs, and is thence exhaled in respira-
tion.

A second class of occasional causes consists of those which, by acting
on the epigastric centre, determine, by sympathy, a cessation of the pulsa-
tions of the heart and the syncope necessarily attending this sensation.
Such are the violent emotions of the soul, terror, an excess of joy, an ir-
resistible aversion to certain kinds of food, the dread which is felt on the

286

unexpected sight of an object, the disagreeable impression occasioned
by certain odours, 8cc. In all these cases, there is felt, in the region of
the diaphragm, an inward sensation of a certain degree of emotion. From
the solar plexus of the great sympathetic nerve, which, according to the
general opinion, is considered as the seat of this sensation, its effects ex-
tend to the other abdominal and thoracic plexuses. The heart, the great-
er part of whose nerves arise from the great sympathetic, is particularly
affected by this sensation. Its action is, at times, merely disturbed by it,
and at other wholly suspended. The pulse becomes insensible, the coun-
tenance pale, the extremities cold, and syncope ensues. This is the course
of things, when a narcotic or poisonous substance has been taken into
the stomach; when this viscus is much debilitated, in consequence of
long fasting, or when it contains indigestible substances; in colic, and in
hysterical affections.

The last class of occasional causes do not act directly, and produce
syncope only at a distant period; but the result is always the same. It
happens, in all the cases, that as the arteries of the head no longer receive
as much blood as in health, the brain falls into a kind of collapse, which
occasions a momentary cessation of the intellectual faculties, of the vital
functions, and of voluntary motion.

Morgagni, in treating of diseases, according to their anatomical order,
ranks lypothymia among the affections of the chest, because the viscera
contained in that cavity, show marks of organic affection, in persons who,
during life,, were subject to frequent fainting.

The compression of the brain, by a fluid effused on the dura mater, in
\vounds of the head, does not produce real syncope, but rather a state of
stupor. All causes, acting in this manner on the brain, produce coma-
tose and even apoplectic affections. When a man, on being exasperated,
falls into a violent and ^sudden fit of passion, his face becomes flushed,
and he is affected with vertigo and fainting. There is no loss of colour,
no loss of pulse; the latter, on the contrary, generally boats with more
force. This is not syncope, but the first stage of apoplexy, occasioned
by the mechanical pressure on the brain, towards which the blood is car-
ried suddenly and in too great a quantity.

I might support this theory of syncope, by additional proofs drawn
from the circumstances which favour the action of the causes giving rise
to affections of this kind. For instance, syncope comes on, almost al-
ways, when we are in an erect posture; and in such a case, it is right to
lay the patient in a horizontal posture. Patients debilitated by long dis-
eases, taint the moment they attempt to rise, and recover on returning
to the recumbent posture. Now, how are we to explain this effect of
standing, in persons in whom the mass of humours is much impoverished,
and whose organic action is extremely languid, unless by the greater dif-
ficulty to the return of the blood, from the more depending parts, and on
the difficulty in ascending, of that which the contractions of the heart
send towards the head ? The phenomena of the circulation, are, under
such circumstances, more subject to the laws of hydraulics, than when
the body is in a state of health ; the living solid yields more easily to the
laws of physics and mechanics, and, according to the sublime idea of the
father of physic, our individual nature approaches the more to universal
nature.

CXLVIII. Of the motions of the brain. Are the alternate motions of
elevation and depression seen, when the brain is exposed, exclusively

387

isochronous to the pulsations of the heart and arteries, or do they cor-
respond, at the same time, to those of respiration ? Such is the physio-
logical problem, of which I am about to attempt the solution.

Those authors who admit the existence of motions in the dura mater,
do not agree as to the cause which produces them. Some, and among
others, Willis and Bagiivi, thought they had discovered muscular fibres,
and ascribed these motions to their action: others, as Fallopius and Bau-
hinus, attributed these motions to the pulsations of the arteries of that
membrane. The dura mater possesses no contractile power; its firm
adhesion to the inside of the skull, would, besides, prevent any such mo-
tion. The motion observed in this membrane is not occasioned by the
action of its vessels; for, as Lorry observes, the arteries of the stomach,
of the intestines, and of the bladder, do not communicate any motion to
the parietes of these hollow viscera; and yet, in number and size, they
at least equal the meningeal arteries.

The motion observed in the dura mater is communicated to it by the
cerebral mass which this membrane covers; and this opinion of Galen,
adopted by the greater number of anatomists, has been placed beyond a
doubt, by the experiments of Schlitting, of Lamure, Haller, and Vicq-
d'Azyr. They have all observed, that on removing the dura mater, the
brain continued to rise and fall; and, with the exception of Schlitting,
they agreed that the brain, absolutely passive, received from its vessels
the motions in which the dura mater partook: but are these motions
communicated by the arteries or by the cerebral veins, and by the sinuses
in which these terminate; or, in other words, are they isochronous to
the beats of the pulse, or to the contraction and successive dilatation of
the chest, during respiration.

Galen, in his treatise on this function, says, that the air admitted into
the pulmonary organ distends the diaphragm, and is conveyed along the
vertebral canal into the skull. According to this writer, the brain rises
during the enlargement of the chest; and it sinks, on the contrary, when
the parietes of this cavity are brought nearer to its axis. Schlitting, in
a memoir presented to the Academy of Sciences, towards the middle of
the last century, maintains that these motions take place, in a different
order; the elevation of the brain corresponding to expiration, and its de-
pression to inspiration. Conceiving that he has determined this fact by
a sufficient number of experiments, he does not enter into any explana-
tion; and concludes his inquiry, by asking whether the motions of the
brain are occasioned by the afflux of air, or of blood, towards that organ.

Haller and Lamure attempted to answer this difficulty. They both
performed a number of experiments on living animals, acknowledged
the fact observed by Schlitting, and explained it in the following man-
ner: as well as this last anatomist, Lamure believed that there is a va-
cuum between the dura and pia mater; by means of which, the motions
of the brain might always be performed. The existence of such vacuum
is disproved, by the close contact of the membranes between which it is
supposed to exist.

During expiration, continues Lamure, the parietes of the chest close
on themselves, and lessen the extent of this cavity. The lungs, pressed
in every direction, collapse; the curvature of their vessels increases, and
the blood flows along them with difficulty. The heart and great vessels
thus compressed, the blood carried off by the upper vena cava to the
right auricle, cannot be freely poured into this cavity which empties

288

itself, with difficulty, into the right ventricle, whose blood is unable to
penetrate through the pulmonary tissue. On the other hand, as the lungs
compress the vena cava, a regurgitation takes place of the blood which
it was conveying to the heart; forced back along the jugulars and verte-
brals, it distends these vessels, the sinus of the dura mater which empty
themselves into them, and the veins of the brain which terminate in
these sinuses. Their distension accounts for the elevation of the cerebral
mass soon followed by depression, when, on inspiration succeeding expi-
ration, and on the lungs dilating, the blood which fills the right cavities
of the heart can freely penetrate into the pulmonary substance, and make
way for that which the vena cava is bringing from the superior parts of
the body.

Haller considered this reflux as very difficult, the blood having to rise
against its own gravity; and he admitted Lamure's explanation only in
the forcible acts of respiration, as in coughing, laughing, and sneezing.
He maintained that, in a state of health, there is to be observed, during
expiration, a mere stagnation of the blood, in the vessels which bring it
from the internal parts of the skull. He further admits, on the testimony
of a great number of authors, another order of motions depending on
the pulsations of its arteries; so that, according to Haller, the cerebral
mass is incessantly affected by motions, some of which depend on respi-
ration, while others are quite independent of it.

Lastly, according to Vicq-d'Azyr, the brain, on being exposed, pre-
sents a double motion, or rather, two kinds of motion, from without; the
one from the arteries, and, which is least remarkable, the other from the
alternate motions of respiration.

CXLIX. This opposition between authors of reputation, and whose
theories have, in general, been adopted, induced me to repeat the experi-
ments which each of them brings in support of his own opinion, and to
perform further experiments on this subject. My investigation soon con-
vinced me, that these authors had given a statement of their opinions, and
not of the fact itself. In fact, the alternate motions of elevation and
depression observed in the brain, are isochronous to the systole and dia-
stole of the arteries at its base. The elevation of the brain corresponds
to the dilatation of these vessels, its depression to their contractions.
The process of respiration has nothing to do with this phenomenon, and
even admitting the stagnation of the regurgitation of the blood in the
jugular veins, the arrangement of the veins, within the skull, is such, that
this stagnation or reflux could not produce alternate motions of the cere-
bral mass.

The brain receives its arteries from the carotids and vertebrals, after
they have entered the skull, the former along the carotid canals, the lat-
ter through the foramen magnum of the occipital bone. It would be use-
less to describe their numerous divisions, their frequent anastomoses, the
arterial circle, or rather polygon formed by these anastomoses, and by
means of Avhich the carotid and vertebral arteries communicate together,
by the side of the sella turcica. Haller has given a very correct view and
an excellent description of this part*. The account of the internal caro-
tid artery published by that great anatomist is, according to Vicq-d'Azyr,
a chief-d'oeuvre of learning and precision ; the same encomium might be

Fasciculi Anatomici, F. 7, tab. 2,

289

bestowed on the latter who gave a superb dra\ving of the same part. I
shall content myself with observing, that the principal arterial trunks
going to the brain, are situated at the base of this viscus ; that the
branches into which these trunks divide, and the subdivisions of these
branches, are, likewise, lodged at its base in a number of depressions,
and that, in the last place, the arteries of the brain do not penetrate into
its substance, after they have undergone in the tissue of the pia mater,
which appear, completely vascular, very minute subdivisi -ns.

The vessels which return the portion of blood which has not been
employed in the nutrition and growth of the brain, are on the contrary,
situated towards its upper part, between its convex surface, and the arch
of the cranium, each convolution contains a great vein which opens into
the superior longitudinal sinus. The vena Galeni which deposits into the
sinus, the blood brought from the choroid plexus; small veins which
open into the cavernous sinuses; others, likewise very minute, which
passing through the foramina in the alse majores of the sphenoid bone,
contribute to form the venous plexus of the zygomatic fossa, are the only
exceptions to this general rule.

This being laid down in the arrangement of the arteries and veins, let
us examine what will be the effect of their action, with regard to this
viacus.

The contractions of the heart propel the blood into the arterial tubes,
which experience especially at the place of their curvatures, a manifest
displacement, at the time of their dilatation. All the arteries situated
at the base of the brain, experience both these effects at once. Their
united efforts, communicate to it a motion of elevation succeeded by de-
pression, when by their contraction, they re-act on the blood which fills
them.

These motions take place, only as long as the skull remains entire; this
cavity is too accurately filled, and there is no void space between the
membranes of the brain. Lorry who, with good reason, denied the ex-
istence of s«ch a space, committed an equally serious anatomical mis-
take in asserting, that as no motion could take place, on account of the
state of fulness of the skull, it was effected in the ventricles, which he
considers as real cavities, but which, as Haller has shown, are, when in a
natural state, merely surfaces in contact. No motion actually takes place,
except in those cases in which there is a loss of substance in the parietes
of the skull.

It is easy to conceive, however, that the brain which is soft and of weak
consistence, yields to the gentle pressure of ics arterial vessels. Does
not this continued action of the heart on the brain, explain in a satisfactory
manner, the remarkable sympathy between those two organs, linked by
such close connections ? It is, besides, of very manliest utility, and con-
nected with the return of the blood distributed to the cerebral mass and
to its envelopes. The veins which bring it back, alternately compressed
against the arch of the skull, empty themselves more easily into the
sinuses of the dura mater, towards which their course is retrograde, and
unfavourable to the circulation of the blood which they pour into them.

When any thing impedes the free passage of the blood through the
lungs, it stagnates in the right cavities of the heart; the superior vena
cava, the internal jugulars, and consequently the sinuses of the dura
mater, and the veins of the brain which terminate in them, are gradual-
ly distended ; and if this dilatation were carried to a certain degree, the

2O

veins of the brain, placed between it and the arch of the skull, would tend
to depress it towards the base of that cavity. If this dilatation, at first
sight, were carried beyond the extensibility of these vessels, their rup-
ture would occasion fatal effusions. It is in this manner, that some
authors have explained sanguineous apoplexy.

It will be objected, perhaps, that many of the sinuses of the dura mater
are at the base of the skull, and that, consequently, their dilatation must
tend to raise the cerebral mass.

But the greater part of these sinuses are connected only with the cere-
bellum and the medulla oblongata, of which it has not yet been possible
to ascertain the motions. These sinuses are almost all lodged in the edges
of the falx and of the teutorium cerebelli. The cavernous sinus in which
the ophthalmic vein disgorges itself, the communicating sinuses, which
allow the blood of one of these sinuses to pass into the other, are two in-
significant to produce a raising of the cerebral mass. Lastly, the resist-
ance of their parietes, formed chiefly by the dura mater, must set strait
bounds to their dilatation ; the spongy tissue which fills the interior of
the cavernous sinuses, still makes this dilatation and the reflux of the
blood more difficult,

CL. It is enough to prove, by reasons drawn frorn^ the disposition of
parts, that the motions of the brain are communidfcted to it, by the col-
lection of arteries at its base; the fact must yet be established upon ob-
servation, and placed beyond doubt, by positive experiments. The fol-
lowing are what I have attempted for this purpose :

A. I have first repeated the observation of some authors, and ascer-
tained, as they did, that the pulsations felt on placing the finger on the
fontanels of the skulls of new-born infants, correspond perfectly to the
beatings of the heart and arteries.

B. A patient, trepanned for fracture, with effusion on the dura mater,
enabled me to see the brain, alternately rising and falling. The rising
corresponded with the diastole, the falling with the systole of the arte-
ries.

C. Two dogs, trepanned, exhibited the same phenomenon, in the
same relation, to the dilatation and contraction of the arteries.

D. I removed, carefully, the arch of the skull, on the body of an adult.
The dura mater, disengaged from its adhesions to the bones which it
lines was preserved, perfectly untouched. I afterwards laid bare the main
carotids, and injected them with water. At every stroke of the piston,
the brain showed a very sensible motion of rising, especially when the
injection was forced at once along the two carotids.

E. I have injected the internal jugular veins. The cerebral mass re-
mained motionless. Only the veins of the brain, the sinuses of the dura
mater dilated. The injection having been kept up for some time, there
resulted from it a slight swelling of the brain : when driven with more
force, some of the veins burst, and the liquor flowed out. The same in-
jection being made with water strongly reddened, the surface of the
brain became coloured with an intense red. To see clearly this effect,
you ought, after removing the arch of the skull, to divide, on each side,
the dura mater, on a level with the circular incision of the skull, then
turn back the flaps towards the upper longitudinal sinus.

F. The internal jugular veins having been laid open, while the injec-
tion was forced along the main carotids, each time the piston was pushed
forward, the venous blood flowed with the greatest impetus j a clear proof

£91

.of the manifest influence of the motions of the brain, on the course of
the blood in its veins, and in thesinuses of the dura mater. This experi-
ment had been already performed by other anatomists, and amongst
others, byRuysch, with a view of proving the immediate communication
between the arteries and veins. This communication, which is, at pre-
sent, universally acknowledged, may be proved by other facts. This one
is evidently any thing but conclusive.

G. In a trepanned dog, I tied successively the two carotids. The
motions of the brain abated, but did not cease. The anastomoses of the
vertebrals, with the branches of the. carotids, account for this pheno-
menon.

H. I took a rabbit, a gentle creature, easy to confine, and very well
adapted for difficult experiments : after laying bare the brain, and ob-
serving that its motions were simultaneous to the beats of the heart, I
tied the trunk of the ascending aorta : the moment the blood ceased ris-
ing to the head, the brain ceased moving, and the animal died.

I. The tying of the internal jugular veins, did not stop the motions of
the brain ; but its veins dilated, and its surface, bared by the removal of
the flap of the dura mater, was sensibly redder than in the natural state.—
The dog became affected with stupor, and expired in convulsions.

The opening of these veins did not hinder the continuance of the mo-
tions 5 they grew fainter only when the animal was weakened by loss of
blood.

K. The opening of the superior longitudinal sinus, the only one that
could easily be opened, did not weaken the motions of the brain. It is
observed that the blood flows out more freely from it, during the eleva-
tion.

D. The compression of the thorax, on human bodies, produces but
a slight reflux in the jugular veins, especially, if, during this compres-
sion, the trunk is kept raised. The reflux is greater, when the trunk is
laid flat.

These experiments might be varied and multiplied ; if, for instance,
the injection were thrown, at once, along the vertebral arteries, and the
internal carotids ; but those I have stated are sufficient for my purpose.

Since the first publication of this inquiry, in the Memoirs of the Me-
dical Society,* I have had many opportunities of repeating the observa-
tions and experiments, which serve as a foundation to the theory there
detailed. Among the facts which confirm this theory, there is one that
appears to me worth stating: it would be sufficient by itself, if it were
possible to establish a theory on the observation of a single fact. A
woman, about fifty years of age, had an extensive carious affection of the
skull; the left parietal bone was destroyed, in the greatest part of its ex-
tent, and left uncovered a very considerable portion of the dura mater.
Nothing was easier than to ascertain the existence of a complete corres-
pondence, between the motions of the brain and the beats of the pulse.
I desired the patient to cough, to suspend her respiration suddenly, the
motions continued in the same relation to ea^n other; when she coughed,
the head was shaken, and the general concussion, in which the brain par-

* Memoirs de la Societe Medicale dc Paris, an VII. (1799.) troisieme anne, page 197J
ct suiv.

292

took, might have been mistaken by a prejudiced observer, for the proper
motions of that organ, and depending on the reflux of blood in the veins*

In experiments on dogs, the same motion takes place, when the animal
barks, but it is easy to perceive, that the concussion affecting the brain is
experienced by the whole body, and that the effort of expiration, in bark-
ing, causes a concussion more or less violent.

The patient, mentioned in the preceding observation, died about a
month after I came to the Hospital of St. Louis, in which she had been
for a considerable length of time. On opening the body, the left lobe of
the brain was found softened and in a kind of putrid state; the ichor which
ivas formed, in considerable quantity, flowed outwardly, by a fistulous
opening in the dura ir.ater whose tissue was rather thickened.

CLI. The slight consistence of the brain, which Lorry considers as
favourable to the communication of the motion which its arteries impart
to it, appears to me to be against this transmission. In fact, the dilated
vessels not being able to depress the base of the skull on which they rest,
make their effort against the cerebral mass, and raise it the more easily
(the arch of the skull being removed) from its presenting a certain re-
sistance. If the brain were too soft, the artery would merely swell into
it, and would not lift it. To satisfy one's self of this truth, one need only
observe what happens when the posterior part of the knee rests on a pil-
low, or on any thing of the same sort; then, the motions which the pop-
liteal artery impresses on the limb, are but little apparent ; but they be-
come very visible, if the ham rests on any thing that resists the action on
the other knee, for in stance :— - then the artery which cannot depress it,
exerts its whole action in raising the lower extremity: which it does, the
more easily, from acting against a bony, resisting, and hard part. This
experiment completely invalidates the opinion of Lorry. The want of
analogy will not be objected ; it will not be said that the brain is heavier
than the lower extremity, nor that the sum of the calibres of the internal
carotid and the vertebral arteries, is not greater than that of the popliteal
artery.

This continual tendency of the brain to rise, produces in the end, on
the bones of the skull which resist this motion, very marked effects.
Thus, the interior surface of these bones, smooth, in early life, becomes
furrowed with depressions, the deeper as we advance in aqe. The digi-
tal depressions and the mammillary processss, corresponding to the con-
volutions and windings of the brain, are very evidently the result of its
action on the enclosing parietes. Sometimes it happens, that, at a very
advanced age, the bones of the skull are so thinned by this internal ac-
tion, that the pulsations of the brain become perceptible through the
hairy scalp.

No doubt, the same cause hastens the destruction of the skull by the
fungous tumours of the dura mater. The effort from expansion of the
tumour, which develops itself, is further added, and makes the waste of
the bones more rapid. At the end of a few months, the tumour projects
outwardly, with pulsations plainly simultaneous to the beadnga of the
pulse, as Louis observes in a Memoir inserted among those of the Aca-
demy of Surgery.

1 have shown (CXLIX.) that the opposition of the veins of the brain
and of the sinuses of the dura mater w<xs adverse to the action ascribed
to them, on this viscus. Experiment (E. L.) shows that the stagnation

293

of the blood, or even its regurgitation, could produce only a slow and
gradual distension of the sinuses of the dura mater, and veins terminating
in it, with a slight turgescence of the cerebral mass, if the cause, pro-
ducing the stagnation of the blood or its reflux, prolonged its action to a
partial destruction of the skull.

Lastly, the alternate motions of the brain, said to correspond to those
of respiration, ought to be the beats of the pulse, in the ordinary ratio of
1 to 5. On the contrary, it is easy to satisfy one's self that these mo-
tions are in an inverse ratio, and perfectly simultaneous to the pulsations
of the heart and arteries.

Theresults of the experiments I have stated in that Memoir, compared
to those obtained by justly celebrated inquirers, are too remarkably dif-
ferent not to have induced me to make some attempt at investigating the
cause of our disagreement. For that purpose, I thought it necessary to
examine scrupulously all the circumstances.

The work of Lamure contains anatomical errors, which throw suspi-
cions upon his accuracy. Haller did not himself make the experiments
of which he speaks, in treating of the influence of respiration on the cir-
culation of venous blood. This article is drawn from a thesis defended
at Gottingen by one of his disciples. Lastly, Vicq-d'Azyr attempted no
confirming experiment, and seems to have had in view only the reconcil-
ing all opinions.

No one of those anatomists has distinguished the motions of elevation
impressed on the cerebral mass by the influence of its arteries, from the
swelling of the sinuses of the dura mater, of the veins distributed to it,
and from the tumefaction of the brain which may be caused by difficult
respiration. This mistake would be the more easy, as animals tortured
by the knife of the anatomist, breathe painfully, convulsively, and at
shorter intervals than in their natural state. Schlitting, the first author
of these experiments, appears especially to have confounded the motion
of rising, the real displacement of the brain, with the turgescence of this
viscus. At every expiration, he says, I have seen ths brain rise, that is
to say, swell, and at every inspiration I have seen it fall, that is to say,
collapse.

"Toties animadverti persfiicue — in omni exfiiralione, cerebrum univer sum
ascendere, id est intumescere ; atque in quavis inspiratione iliud descendere, id
est detumescere."

We may, therefore, consider as a truth strictly demonstrated by obser-
vation, experiment, and reasoning, the following proposition : —

The motions observable in the brain, when laid bare, are imparted to it solely
by the pulsations of the arteries at its base, and are perfectly simultaneous to
the fiulsations of these vessels : further, the reflux and stagnation of the venous
blood* are able to swell its substance.

CLII. fiction of the nerves and brain. It is undoubtedly, as Vicq-d'Azyr
has said, by a motion of some sort that the nerves act. ' Setting out from
this simple, idea, one may admit several kinds of nervous motions, the
one operating from the circumference to the centre, it is the motion of
sensation which we are about more particularly to study in this para-
graph ; the other, acting from the centre to the circumference, and this
motion, produced by the will, determines the actitfn of the muscular or-
gans, &c.

In what manner arc the impressions produced on the senses by the bo-
dies which surround us, transmitted, along the nerves to the brain ? Is it

294

through the intervention of a very subtle fluid, or can the nerves, as has
been stated by some physiologists, be considered as vibrating cords ? This
last idea is so absurd, that one cannot help wondering it shduld so long
have been in vogue. A cord that it must vibrate, must be in a state of
tension, along the whole of its length, and fixed at both extremities* The
nerves are not in a state of tension, their extremities, in no degree fixed,
approach towards each other, or recede according to the difference of po-
sition, the tension, the turgescence, the fullness or collapse of the parts,
and vary constantly in their distance from each other. Besides, the ner-
vous cords, situated between pulps, at their origin, and at their termina-
tion, cannot be extended between these two points. The nervous fibre is
the softest, the least elastic of all the animal fibres ; when a nerve is divi-
vided, its two extremities, far from receding by contracting, project, on
the contrary, beyond each other ; the point of sections shows a number
of small granulations of medullary and nervous substance, which flows
through its minute membranous canals. Surrounded by parts to which
they are, to a certain degree, united, the nerves could not vibrate ; lastly,
admittingthe possibility of their being capable of vibrating-, the vibration
of a single filament ought to bring on that of all the rest, and carry con-
fusion and disorder in every motion and sensation.

It is much more probable that the nerves act by means of subtle, invi-
sible, and impalpable fluid, to which the ancients gave the name of ani-
mal spirits: this fluid, unknown in its nature, and to be judged of only by
its effects, must be wonderfully minute, since it eludes all our means of
investigation. Does it entirely proceed from the brain, or is it equally
secreted, by the membranous envelopes of each nervous filament? (Neu-
rilemes, Reil.) To say the truth, one can bring no other proof of the ex-
istence of a nervous fluid, but the facility with which, by means of it, we
are enabled to explain the various phenomena of sensation, and its utility in
explaining these phenomena. These proofs, however, may not appeal-
completely satisfactory to those who are very strict, and who do not con-
sider as proved what is merely probable.

Among the constituent principles of the atmosphere, there are gene-
rally diffused several fluids, such as the magnetic and electric fluids.
Might not these fluids, on entering with the air into the lungs, combine
with the arterial blood, and be conveyed, by means of it, to the brain, or
to the other organs ? Does not the vital action impart to them new qua-
lities, by making them undergo unknown combinations ? Do caloric and
oxygen enter into these combinations which endow fluids with a certain
vitality, and produce on them important changes, and which are not un-
derstood* ? Have not these conjectures acquired a certain degree of
probability, since the analogy of galvanism to electricity, at first suppos-
ed by the author of this discovery, has been confirmed, by the very curi-
ous experiments of Volta, repeated, commented, and explained, by all
the natural philosophers of the present day, in Europet !

The action of the nervous fluid takes place, from the extremity of the

* Were it not for these changes, electricity, magnetism, and galvanism, would suffice
to restore life to an animal recently dead. — Copland.

•J- Galvanism, as yet, has not realized the expectations of physiologists. Chemistry
has derived the greatest advantage from it. It is, at present, with M. M. Davy, The-
nard, and Gay-Lussac, the most powerful agent in the analysis of certain bodies. — Cop-
land,

295

nerves towards the brain, so as to produce the phenomena of sensation,
for, when the nerves are tied, the parts below the ligature lose the power
of sensation, while, as will be seen in the proper place, this action is pro-
pagated <rom the brain towards the nervous extremities, and from the cen-
tre to the circumference, in producing motions of every kind. This dou-
ble current, in contrary directions, may take place in the same nerves,
and it is not necessary to arrange the nerves into two classes of sensation
and of motion.

All the impressions received by the organs of sense, and by the senti-
ent extremities of nerves, are transmitted to the cerebral mass. The
brain is, therefore, the centre of animal life ; all sensations are carried to
it ; it is the spring of all voluntary motion ; this centre is to the functions
of relation, as the heart to the functions of nutrition. One may say of
the brain, as of the heart, omnibus dat et ab omnibus accijiit. It receives
from all, and gives to all*.

The existence of a centre, to which all the sensations are carried, and
from which all motions spring, is necessary to the unity of a thinking
being, and to the harmony of the intellectual functions. But is this seat
of the principle of motion and of sensation, circumscribed within the nar-
row limits oi' a mathematical point, or rather should it not be considered
as diffused over nearly the whole brain ? The latter appears to me the
more probable opinion; were it otherwise, what could be the use of those
divisions of the organ into several internal cavities; what could be the
use of those prominences all varying in their form; and of the arrange-
ment of the two substances which enter into their structure ? We may
conjecture, and with considerable probability, that each .perception, each
class of ideas, each faculty, is assigned to some peculiar part of the brain.
It is, indeed, impossible to determine the peculiar functions of each part
of the organ ; to say what purpose is served by the ventricles, what is the
use of the commissures, what takes place in the peduncles ; but it is im-
possible to study an arrangement of such combination, and to believe
that it is without design, and that this division of the cerebral mass, into
so many parts, so distinct, and of such various forms, is not relative to
the different function, which each has to fill in the process of thought.
That ingenious comparison, mentioned in the panegyric of Mery, by
Fontenelle, is very applicable to the brain. " We anatomists," he once
said to me, 4i are like the porters in Paris, who are acquainted with the
narrowest and most distant streets, but who know nothing of what takes
place in the houses." What then are we to think of the system of Gall,
and of his division of the outside of the skull into several compartments,
•which, according to the depression or projection of the osseous case, in-
dicate the absence or the presence of certain faculties, moral or intellec-
tual? I cannot help thinking, that this physiological doctrine of the func-
tions of the brain, resting on too few well observed facts, is frivolous; while
his anatomical discoveries on the anatomy of this organ, and on the ner-
vous system, are of the highest importance, and well founded.

CLIII. Analysis of the Understanding. In vain were the organs of
sense laid open to all impressions of surrounding objects ; in vain were
their nerves fitted for their transmission : these impressions were to us as
if they had never been, were there not provided a seat of consciousness
in the brain. For it is there, that every sensation is felt ; light and sound,

* See APPENDIX, Note E E,

296

and odour, and taste, are not felt in the organs they impress ; it is the
sensitive centre that sees, and hears, and smells, and tastes. You have
only to interrupt, by compression of the nerves,, the communication be-
tween the organs and the brain, and all consciousness of the impressions
of objects, all sensation is suspended.

The torturing pains of a whitlow cease, if you bind the arm so strongly
as to compress the nerve which carries the sensation to the brain. A
living animal, under experiments, suffers nothing from the most cruel
laceration, if you have first cut the nerves of the parts on which you are
operating. To conclude, the organs of sense, and the nerves which com-
municate between them and the brain, shall have suffered no injury,
shall be in perfect state for receiving and transmitting the sensitive im-
pression, yet no phenomena of sensation can take place, if the brain be
deceased; when it is compressed, for instance, by a collection of fluid, or
by a splinter from the skull in a wound of the head. This organ is,
therefore, the immediate instrument of sensations, of which impressions
made on the others are only the occasional causes. This modification of
sensibility, which serves to establish the relations of the living being, with
objects without, would be correctly denominated cerebral sensibility; but
that even in animals without brain, or distinct nervous system, it is very
manifest. The sensibility, in virtue of which the polypus dilates his ca-
vity, for the admission of his prey, and contracts itself to retain it, is in
fact, quite distinct from that sensibility of nutrition, by which its substance
is enabled to take to itself nutritious juices.

The brain, as Cabanis has well expressed it, acts upon the impression
transmitted by the nerves, as the stomach upon the aliments it receives
by the oesophagus : it does, in its own way, digest them : set in motion by
the impulse it receives, it begins to re-act; and that re-action isthe/zer-
cefitive sensation, or perception. From that moment, the impression be-
comes an idea, it enters as an element into thought 5 and becomes sub-
ject-to the various combinations that are necessary to the phenomena
of understanding*.

CLIV. Our sensations are nothing but modifications of our being; they
are not qualities of the objects : no body has colour to the blind from
birth: the rose has lost its most precious quality to him who has lost his
smell : he knows it from the anemone, only by its colour, its figure, 8cc.
We perceive nothing but within ourselves. It is only by habit, only by
applying different senses to the examination of the same object, that we
are at least able to separate it from our own existence ; to conceive of it
as distinct from ourselves, and from the other bodies with which we are
acquainted ; in a word, to refer to outward objects the sensations that
take place within ourselves. Our ideas come to us, only by the senses;
there are none innate as was imagined till the time of Locke, who has al-
lotted to the refutation of this error a large part of his valuable work on
the Human Understanding. The child that opens its eyes to the light,
is prepared for the acquisition of ideas, by this merely, that it has
senses; that it is susceptible of impressions from the objects that sur-
round it.

It is inaccurate, however, to compare, as some philosophers have done,

* I ought to observe, that the terms thought and understanding are, in my opinion,
synonymous ; both are alike, an abridged expression of the whole of the operations of
the sensitive centre. — Author's Note,

297

the brain of a child new born to a blank tablet, on which are to be figured
all the future acts of his intelligence. If sensation came only from with-
out, if the external senses were the only organs that could send impres-
sions to the cerebral centre, the understanding, at the moment of birth,
had indeed been nothing, and the comparison of its organ to a sheet of
white paper, or to a slab of Parian marble, on which not a character were
drawn, had been perfectly correct. But we are compelled to acknow-
ledge with Cabanis, two sources of ideas quite distinct from each other,
the external senses, and the internal organs. These inward sensations,
springing from functions that are carrying on with us, ar<* the cause of
those instinctive determinations by which the new-born child seizes
the nipple of its mother, and sucks the milk by a very complicatedpro-
cess, which directs the young of animals the moment after birth, and
sometimes in the very act of birth, while the limbs are yet engaged
in the Vagina, to seize upon the dug of their dam. Instinct, as the au-
thor just quoted, has very justly observed, sfv*ngs from impressions
received by the interior organs, whilst reaso™ng is the produce of exter-
nal sensations; and the etymology of the w->rd instinct, composed of two
Greek words, signifying « to prick," *c- "within,'* agrees with the
meaning we assign to it.

These two parts of the understanding, reason and instinct, unite and
blend together, to produce the intellectual system, and the various deter-
minations of mental action. But the part that each bears in the genera-
tion of ideas, is very different in animals, whose grosser external senses
allow instinct to predominate; and in man, in whom the perfection of
these senses, and tbt art of signs, which perpetrate the transient thought,
augment the power of reason, while .they enfeeble instinct. It is easy to
conceive, that the brain, assailed by a crowd of impressions from with-
out, will regard less attentively, and therefore suffer to escape the greater
part of those that result from internal excitation. Instinct is more vigo»
rous in savage man, and its relative perfection is his compensation for the
advantages which superior reason brings to man in civilization. The
moral and intellectual system of the individual, considered at different
periods of life, owes more to internal sensation, the less it is advanced;
for, instinct declines as reason is strengthened and enlarged.

Thus, though all the phenomeixi of understanding have their source in
physical sensibility, this sensibi/ity being set in action by two sorts of
impressions, the brain of an in/ant just born, has already the conscious-
ness of those which spring frojzi the internal motion, and it is from these
impressions that it executes certain spontaneous movements, of whieh
Locke and his followers coyfd find no explanation : accordingly, thepar-
tizans of innate ideas, looked i,-pon them as the strongest confirmation of
their system; but these kleas, anterior to all action of outward objects on
the senses, are simple, few, and extending to a very small number of
wants: the child is but a fevr hours old, and already it expresses a multi-
tude of sensations, that throng upon it from the instant of its birth, sen-
sations, which have passed to the brain, combined themselves there, and
entered into the action of the will, with a velocity which equals, if it does
not surpass, that of light.

It U only, after laying down between the sources of our knowledge, a
very exact line of demarcation, after scrupulously distinguishing the ra-
tional from the instinctive determinations, acknowledging that age, sex,
temperament, health, disease, climate, and habit, which modify our phy-

2 P

298

sical organization, must, by a secondary effect, modify these last, that we
can possibly understand the diversity of humours, of opinions, of charac-
ters, and of genius. He who has well appreciated the effect, on the jWlg-
ment and reason, of the sensations that spring from the habitual state of
the internal organs, sees easily the origin of those everlasting disputes on
the distinction between the sensitive and the rational soul; why some
philosophers have believed man solicited for ever by a good or an evil ge-
nius ; spirits which they have personified under the names of Oromazes,
and Arim'anes, betwixt whom they imagined eternal war; the contest of
the soul with the senses, of the spirit with the flesh, of the concupiscent
and irascible with the intellectual principle, .that contradiction which St.
Paul laboured under, when he said in his Epistle to the Romans, that his
members were in open war with his reason. These phenomena which
suggest the conception of a two-fold being (Homo duplex, Buffon,) are
nothing but a necK^ary strife betwixt the determinations of instinct and
the determinations of^^on 5 between the often times imperious wants
of the organic nature, antN<he judgment which keeps them under, or de-
liberates on the means of SHisfying them, without offending received
ideas of fitness, of duty, of relr^on, &c.

CLV. A being, absolutely desr*ute Of sensitive organs, would possess
only the existence of vegetation: iiVesense were added, he would not
yet possess understanding, because, as^qndillac has shown, the impres-
sions produced on this only sense, wouldN^t admit of comparison ; it
would end in an inward feeling, a perception ^pxistence, and he would
believe the things which affected him to be a p^t of his being. The
fundamental truth, so completely made out by mode^ metaphysicians, is
found distinctly stated in the writings of Aristotle 5* a^d there is room
for surprise, that that father of philosophy should have merely recognised
it, without conforming to its doctrines ; but, still more that it should
,have been for so many ages disregarded by his successors. So absolute-
ly is sensation the source of all our knowledge, that even the measure of
understanding is according to the number and perfection of the organs
of sense ; and that by successively depriving them of the intelligent be-
ing, we should lower, at each step, his intellectual nature 5 whilst the ad-
dition of a new sense to those we now possess, might lead us to a multi-
tude of unknown sensations and ideas> would disclose to us in the beings
we are concerned with, a vast variety of new relations, and would greatly
enlarge the sphere of our intelligence,

The impression, produced on any organ, by the action of an outward
body, does not constitute sensation ; h is farther requisite, that the im-
pression be transmitted to the brain, that it be there perceived, that is, felt
by that organ ; the sensation then becomes fitvception, and this first modi-
fication supposes, as is apparent, a centrak orgwi, to which the impres-
sions on the organs may be carried. The cerebral fibres are, more or less
disturbed, by the sensations sent to them, at once> from all the organs of
sense 5 and we should acquire but confused notions of the bodies from
which they proceed, if one stronger perception did not silence, as it were,
the rest, and fix the attention. In this concentration of the soul upon a
single object, the brain is feebly stirred by many sensations that leave no

* JVil est in intelleclu, quod non prius fuerit in scnsu .-—Nisi intellectus ipset as Leibnitz
has Very justly added. See APPENDIX, Note E E.

299

trace ; it is thus, that after the attentive perusal of a book, we have lost
the sensations that were produced by the different colour of the paper and
the letters.

When a sensation is of short duration, our knowledge of it is so light,
that soon there remains no remembrance of it. It is thus, that we do not
perceive, every time we wink, that we pass from light to darkness, and
from darkness to light. If we fix our attention on this sensation, it af-
fects us more permanently. After occupying one's self, for a given time,
with a number of things, with but moderate attention to each; after read-
ing, for instance, a novel, full of events, each of which in its turn has in-
terested us, we finish it without being tired of it, and are surprised at
the time it has taken up.- It is because successive and light impressions
have effaced one another, till we have forgotten all but some of the prin-
cipal actions. Time ought then to appear to us to have passed rapidly,
for, as Locke has well said, in his Essay on the Human Understanding,
" We conceive the succession of times only by that of our thoughts."

This faculty, of occupying one's self long and exclusively with the
same idea, of concentrating all the intellectual faculties on one object, of
bestowing on the contemplation of it alone, a lively and well supported
attention, is found in greater oi»less strength in different minds; an^some
philosophers appear to me to have explained, very plausibly, the differ-
ent capacity of different minds, the various degrees of instruction of
which we are capable, by tbe degree of attention we are a,He to give to
the objects of our studies.

W^ho, more than the man of genius, pauses on the ^iamination of a
single idea, considers it with more profound reflection, under more as-
pects and relations, bestows on it, in short, more entire attention ?

Attention is to be considered as an act of the/will? which keeps the
organ to one sensation, or prepares it for that/ensation, so as to receive
it more deeply. To look, is to see with alien/on; to listen, is to hear at-
tentively: the smell, the taste, in the same /ay, are fixed upon an odour,
or a flavour, so as to receive from them tXe fullest impression. In all
these cases, the sensation may be involun/ary, but the attention by which
it is heightened, is an act of the will. 7"*s distinction has already been
well laid down with regard to the feyiing? which is only the touch ex-
erted under the direction of the vrlW

According to the strength or fastness of the impression that a sensa-
tion, or an idea (which is but a ^nsation operated upon by the cerebral
organ,) has produced on the fih/es of that organ, will be the liveliness
and permanence of the recolle/uon. Thus, we may have reminiscence of
it, or recall faintly that we hAve been so affected; or memory, which is a
representation of the object* with some of its characteristic attributes, as
colour, bulk, &c.

The pains that appear to be felt in limbs which we have lost, have not
their place in the part which is left; the brain is not deceived, when it
refers to the foot, the sufferings of which the cause is in -the stump, after
the amputation of the leg or thigh. I have at this moment before me, the
case of a woman and of a young man, whose leg and thigh I took off for
scrophulous caries, of many years standing, and incurable by any other
means. The wound, from the operation, is completely cicatrised. The
stump has not more sensibility than any other part covered by integu-
ments, .since it may be handled without pain. And yet, both at intervals,
and especially when the atmosphere is highly electrified, complain of

300

pains in the limbs which they have lost some months ago. They recog-
nise them, by certain characters, for those of their disease. They, like
all perceptions, are manifestly given in charge to the memory, which
reproduces them, when the cerebral organ repeats the action, once occa-
sioned by the impression of the disease.

Finally, if the brain is easy of excitation, and at the same time, faith-
ful in preserving the impressions it has received, it will possess the
power of bringing up ideas with all their connected and collateral ideas;
of reproducing them, in some sort, by recalling the entire object, whilst
memory presents us with a few of its qualities only. This creative fa-
culty is called the imagination. If it sometimes produces monsters, it is
that the brain, by its power of associating, connecting, combining ideas,
reproduces them in an order not according to nature, gathers them un-
der capricious associations, and gives occasion to many erroneous judg-
ments.

When the mind brings together two ideas, when it compares them,
and determines on their analogy, it judges. A certain number of judg-
ments in series, form a reasoning. To reason, then, is only to judge of
the relations that exist among the ideas with which the senses supply us,
or which are produced by Imagination.

It is, with the faculties of the soul, as with those of the body. When
called into full exertion, the intellectual organ gains vigour; it languishes
in too long impose. If we exercise certain faculties only, they are greatly
developed, to :,he prejudice of the rest. It is thus, that by the study of
mathematics, soundness of judgment is acquired and precision of reason-
ing: to the extinction of imagination, which never rises to great strength
without injury to the judging and reasoning powers. The descriptive
sciences employ especially the memory, and it is seldom that they much
enlarge the minds of tho^e who study them exclusively.

CLVI. Condillac has immortalized his name, by discovering, the first,
and by demonstrating irrefrtgibly that signs are as necessary to the for-
mation as to the expression of ideas; that language is not lessvuseful for
thinking than for speaking; th-ut if we could not attach the notions once
acquired to received signs, they would remain always unconnected and
incomplete; since we should hav* no power to associate and compare
them, and to determine their relations. It is the imperfection or the to-
tal want of signs, for fixing their idt^s, ttvat makes the infancy of the
lower animals perpetual. It is this tint makes it impossible for them
to transmit to another generation, or evtn to Communicate one with ano-
ther, the acquisitions of individual expeiience: which experience is in-
deed, by the same cause, restrained within /ery narrow limits, and con-
fined to a few simple notions, a few ideas resting merely on its wants and
on its powers. If tfcere were not signs to preserve ideas, and to connect
them, memory would be nothing, all impressions would be effaced, soon
after they were felt, all collections of ideas would be dissolved as soon
as formed, (if they could be formed at all) our ignorance would be in-
definitely prolonged, and we should reach old age, with a mind still in
its infancy.

When we reflect on a subject, it is not directly on the ideas, but on the
words expressing them, that the mind operates: we should never have
the idea of numbers, if we had not assigned distinct names to numbers,
whether single or collected. Locke speaks of some Americans, who had
no idea of the number thousand, because the words of their language

301

expressed nothing beyond the number twenty. La Coadamine informs
us, in his narrative* that there are some who count only to three, and the
word they employ to express the number is so complicated, of a pronun-
ciation so long and difficult, that, as Condillac observed, it is not sur-
prising, that having begun with a method so inconvenient, they have not
been able to advance any farther. " Deny, (says this writer) to a superior
mind, the use of letters, how much of knowledge you put out of his
reach, which an ordinary capacity will attain to without difficulty. Go
on, and take from him the use of speech, the lot of the dumb will show
you, how narrow are the limits within which you confine him. Finally,
take from him the use of all sorts of signs, let him be unable to find the
least sign for the most ordinary thought, and you have an ideot*."

We are made acquainted by travellers with certain tribes, so backward
in the art of expressing their ideas by signs, that they seem to serve as a
link between civilized nations and certain species of animals, whose in-
stinct has been perfected by education. One might even assert, that
there is less distance, in respect to intelligence, from a man in that ex-
treme abasement, to the higher animals, than there is to a man of supe-
rior genius, such as Bacon, Newton, or Voltaire.

In another part of the same work, afier having demonstrated, that lan-
guages are real analytic methods, that the sciences may be reduced to
well constructed languages, he shows how powerful is their influence in
the cultivation of the mind. But he shall speak himself with that clear-
ness of expression, which is the characteristic and the charm of his
writings. " Languages are like the ciphers of the geometricians; they
present new views to the mind, and expand it as they are brought nearer
to perfection, The discoveries- of Newton had been prepared for him,
by the signs that had been already contrived, and the methods of calcu-
lation that had been invented. If he had arisen sooner, he might have
been a great man to his own age; but he would not have been the admi-
ration of ours. It is the same in other departments."

The most scanty languages have been formed in the most barren coun-
tries. The savage who strays along- the desert shores of New Zealand,
needs but few signs to distinguish the small number of objects that ha-
bitually impress his senses: the sky, the earth, the sea, fire, shells, the
fish that form his chief food, the quadrupeds, and the vegetable, which
are but few in number, under this severe climate, are all that he has to
name and to know: accordingly, his vocabulary is very small; it has
been given to us by travellers in the compass of a few pages. A copious
language, one capable of expressing a great variety of objects, of sensa-
tions, and of ideas, supposes high civilization in the people among whom
it is spoken. You hear complaints of the perpetual recurrence of the
same expressions, the same thoughts, the same images, in the poetry of
Ossian: but living amidst the barren rocks of Scotland, the bards could
not speak of things, of which nothing, on the soil they inhabited, could
supply them with the idea. The monotony of their languages was in-
volved in that of their impressions, always produced by rocks, mists,
winds, the billows of the ireful ocean, the gloomy heath, and the silent
pine, Sec. The repetition of the same expressions, in the Scriptures,
shows that civilization had not made the same progress among the He-

Kssai sur POrigine des Conuoissances Humaines, sec. 4.

302

brews, as among the Greeks and Romans. The connexion there is be-
tween the genius of a language and the character of the people that
speak it, the influence of climate, of government, and of manners on lan-
guage, the reasons, why the great writers, in every department, appear
together, at the very time in which a language reaches its perfection and
maturity, Sec. these are problems that suggest themselves, and would
well merit our endeavours to obtain solution, did not the investigation
manifestly lead beyond the limits of our inquiry.

Though Cond iliac has said, repeatedly, in his works, that all the ope-,
rations of the soul are merely sensation variously transformed, that all
its faculties are included in the single one of sense; his analysis of thought
leaves still much doubt and uncertainty on the real character and relative
importance of each of her faculties.

The merit of dispersing the mist which covered this part of metaphy-
sics remained for De Tracy. His Elements of Ideology*, leave, nothing
to be wished for on this subject: I shall extract some of its main results,
referring the reader for the rest to the work.

To think is only to feel; and to (eel, is, for us, the same as to exist;
for it is by sensation we know of our existence. Ideas, or perceptions,
are either sensations, properly so called, or recollections, or relations
which we perceive, or, lastly, the desire that is occasioned in us by these
relations. The faculty of thought, therefore, falls in the natural subdi-
vision of sensibility, properly termed memory, judgment, and will. To
feel, properly speaking, is to be conscious of an impression; to remem-
ber, is to be sensible of the remembrance of a past impression; to judge
is to feel relations among our perceptions: lastly, to will is to desire
something. Of these four elements, sensations, recollections, judgments, and
desires, are formed all compound ideas. Attention is but an act of the
will : comparison cannot be separated from judgment, since we cannot
compare two objects without judging them: reasoning is only a repetition
of the act of judging: to reflect, to imagine, is to compose ideas, analy-
zable into sensations, recollections, judgments and desires. This sort of
imagination, which is only certain and faithful memory, ought not to be
distinguished from it.

Finally, want, uneasiness, inquietude, desire, passions, &c. are either
sensations or desires. There is room, therefore, to reproach Condillac
with having divided the human mind into understanding and will only:
because the first term includes actions too unlike, such as sensation, me-
mory, judgment; and with having run into the opposite extreme, in the
too great multiplication of secondary divisions.

CLVII. Disorders of thought. Philosophers would undoubtedly attain
to a much profounder knowledge of the intellectual faculties of man, if
they joined to the study of their regular and tranquil action, that of the
many disordered actions to which they are liable. It is not enough, if
we would understand them aright, to watch their operation when the soul
is undisturbed and at ease: we must follow it in its perturbations and
wanderings : we must see its powers, now separating themselves from
those with which they ought to act; now combining with them under
false perceptions : sometimes, altogether drooping, and sometimes start-
ing into an extreme violence of action, of which we can neither mistake

Elemens dldeologie, par M. Destutt^Tracy, senateur, Membre de 1'Institut.

303

the importance nor the nature ; and, as the greater part of our ideas are
derived from the analogies we are able to discern among the objects that
supply them, amidst these troubles of human passion and human reason,
we learn to conceive more profoundly of their nature, than if we had
been satisfied with observing them in the calm of their natural condition.
The observation of mania is yet too imperfect in the number, variety,
and precision of its facts, to fix the classification of the species of mental
alienation, according to the intellectual faculty that is disordered in each.
Professor Pinel has,' nevertheless, ventured to ground his distinctions of
the species of mania on the labours of modern psychologists, and shown
that all might be referred to five kinds, which he marks by the names of
melancholy, of mania without delirium, mania with delirium, dementia,
and idiotcy*. In the first four kinds, there is perversion of the mental fa-
culties, which are in languid or excessive action. We are not to look
for the cause of these derangements in vice of original conformation ;
for, melancholy, mania with or without delirium, and madness, scarcely
ever appear before puberty. It is agreed, among observers, that almost
all maniacs have become so, between twenty and forty years old : that
very few have lost their reason either before or after this stormy period
of life, wherein men, yielding, by turns, to the torments of love and of am-
bition, of fear and of hope, to the sweet illusions of happiness, and the
realities of suffering, consumed with passions for ever revivings often re-
pressed, and rarely satisfied, feel their intellectual powers impaired, an-
nihilated, or abused by that tempest of the moral nature, which has well
been compared to the storms which, in their violence, lay desolate the
flourishing earth.

We are compellsd to grant, that our acquaintance with the structure
of the brain and of the nerves is too imperfect, thai dissections of the
bodies of maniacs have been too few, and those often by physiciansf too
little familiar with the minute structure of the sensitive organ, to war-
rant us in asserting or denying, that derangement of intellect depends
constantly on organic injury; though it is highly probable, many facts, at
least, collected by observers, who, like Morgagni, deserve the utmost
confidence, authorise the belief, that the consistence of the brain is in-
creased in some maniacs who are distinguished by the most obstinate and
unvarying adherence to their ruling ideas ; that it is, on the other hand,
soft, watery, and in a kind of incipient dissolution, in some others, whose
incoherent ideas after their aptitude for association, and for transforma-
tion into judgments is gone, succeed one another rapidly, and seem to
pass away without a trace, Etc.

If, in the multitude of maniacs, the organ of the understanding suffer
only imperceptible injury, it is very remarkably changed in idiots. The
almost entire obliteration of the intellectual faculties, which constitutes
idiocty, when it is not brought on by some strong and sudden shock, some
unexpected and overwhelming emotion breaking down at once all the
springs of thought, when it is an original defect, always connected with
mal-conformatiori of the skull, with the constraint of the organs it en-
closes. These defects of organization lie, as M. Pinel observes, in the

* For move ample explanation I must refer to the work. Traite medico-philosophique
tnir r Alienation mentals on la Manic, par. P. Pinel. Paris, 1800.— Copland.
f This censure is especially applicable to the researches of Dr. Greding. — Copland,

304

excessive smalhiess of the head, to the whole stature, or to the want of
proportion among the different parts of the skull. Thus in the idiot,
whose head is given in the work on mania (pi. 2. fig. 6.) it is only
the tenth of the whole height, whilst it should be something more than a
seventh, if we take the Apollo of Belvidere as the type of the ideal per-
fection of the human figure. An idiot, whom I occasionly see, has the
occipital extremity of the head so much contracted, that the large extre-
mity of the oval formed by the upper face, instead of being placed at the
back, as in other men, is, on the contrary, turned forwards and answers
to the forehead, which itself slopes towards the sinciput. The vertical
diameter of the skull is inconsiderable. The head, thus shortened from
above downwards, is much flattened on the sides. The hands and feet
are very small, and often cold $ the genitals, on the contrary are ex-
tremely large*.

In two other children, equally idiots, and now in the Hospital of St.
Louis, the skull, very large behind, ends in a very contracted extremity,
and the forehead is very short, and not more than two inches and a half
wide, measuring from the semi-circular process, which terminates, at the
upper part of the temporal fossa, to the commencement of the same pro-
cess on the other side. The excessive growth of the genitals is not less
conspicuous ; they are, in these two children, one ten, the other twelve
years old, as well as in the first of whom I spoke, who is fourteen, of
larger size than is commonly seen after the appearance of puberty.
There is nothing to indicate that this season is attained by these three
idiots.

The same excess of growth is found, more conspicuously among the
cretins of the Valais, idiots who (in conseqnence of a weak and degraded
organization) are prone to lascivousness and the most frequent onanism.

This sort of opposition in the relative energy of the intellectual organ,
and of the system of reproduction, in the developement of the brain, and
that of the parts of generation is a phenomenon which must strongly in-
terest the curiosity and engage the attention of physiologists. Who is
there unacquainted with that enervation of the understanding, that in-
tellectual and physical debility, which indulgence in the pleasures of love
brings on, if we exceed ever so little the bounds of scrupulous modera-
tion? Castration modifies the moral character of men and animals, at
least as powerfully as their physical organization, as M. Cabanis has
shown, in treating of the influence of the sexes on the origin and growth
of the moral and intellectual powers.

CLVIII. Our physical, therefore, holds our moral nature under a
strict and necessary dependence : our vices and our virtues, sometimes
produced and often modified by social education, are frequently, too, re-
sults of organization. To the conclusive proofs which the philosopher I
have just named, who is an honour to his profession, brings forward of the
influence of the physical on the moral human being, I will only add a single
observation. It is not certainly, the first that has been made of the kind;
but none such, I believe, has yet been published. The reader recollects,
I have no doubt, the old woman of whom I have spoken in treating of the

* As a general rule, the intellectual faculties are in an inverse ratio to the magnitude
of the genital organs. This is particularly exemplified in the ancient statuary, and »
supported by comparative anatomy. — Gadman.

305

motions of the brain, which an enormous caries of the bones of the.
skull gave an opportunity of observing in her. I wiped off the sanious
matter which covered the dura mater, and I, at the same time, questioned
the patient on her situation : as she felt no pain from (.he compression of
the cerebral mass, I pressed down lightly the pledget of lint, and on a
sudden the patient, who was answering my questions rationaily, stopped
in the midst of a sentence, but she went on breathing, and her pulse con-
tinued to beat : I withdrew the pledget ; she said nothing : I asked her if
she remembered my last question : she said not. Seeing that the expe-
riment was without pain or danger, I repeated it three times, and thrice
I suspended all feeling and all intellect.

A man trepanned for a fracture of the skull, with effusion of blood and
pus on the dura mater, perceived his intellectual faculties going, the
consciousness of existence growing benumbed and threatening to ceasey
at the interval of each dressing, in proportion as the fluid collected.

There are surgical observations on wounds of the head, containing se-
veral facts that may be connected with the preceding observations. There
is no one who has had syncope of more or less continuance, but knows
that the state is without pain or uneasiness, and leaves no consciousness
of what passed while it lasted. It is the same after an apoplexy, a fit
of epilepsy, &c.

The history of temperament supplies us with too many examples of
the strict connexion which there is between the physical organization and
the intellectual and moral faculties, to leave any necessity for dwelling
longer on this truth, which no one questions; but which no philosopher
has yet followed into all its consequences.

CLIX. An English writer, in a work on the history of mental aliena-
tion*, has traced, better than had before been done, the physiological
history of the passions, which he looks upon as mere results of organiza-
tion, ranking them among the phenomena of animal economy, and with
abstraction of any moral notion that might attach to them.

All passion is directed to the preservation of the individual or the re-
production of the species. They may be distinguished, therefore, like
the functions, into two classes!' In the second, we should find parental
love, and all the affections that protect our kind through the helplessness
of its long infancy.

But Crichton, with the greater part of metaphysicians and physiolo-
gists, appears to me to have settled incorrectly the meaning that should be-
long to the word passion. When he gives this name to hunger, an in-
ward painful sensation, the source of many determinations of many kinds,
a powerful mover of savage «nd civilized man, — to the anxiety which at-
tends the breathing an air deficient in oxygen,-— to the impressions of ex-'
cessive heat and cold,— to the troublesome sensations produced by the ac-
cumulation of urine and fecal matter,— to the feeling of weariness and
fatigue that is left by violent exertions, — he confounds sensation with the
passions or desires which may spring from it.

It is to avoid extreme wants, of which a vigilant foresight perceives afar
off the possibility — it is to satisfy all the factitous wants which society
and civilization have created, that men condemn themselves to those agi-

* An Inquiry into the Nature and Origin of Mental Derangement— London, If 98,
2vols. 8vo.<
t See APPENDIX, Note B £.

20

306

f atlotts, of which honour, reputation, wealth and power, are the uncertain
aim. Our passions have not yet been analyzed with the same care as our
ideas: no one has yet duly stated the differences there are, in respect to
their number and energy, betwixt savage man, and man in the midst of
civilized and enlightened society.

As the habitual state of the stomach, of the lungs, of the liver and
internal organs, is conncted with certain sets of ideas ; — as every vivid sen-
sation of joy or distress, of pleasure or pain, brings on a feeling of anxie-
ty in the prsecordia, — the ancients placed in the viscera the seat of the
passions of the soul: they placed courage in the heart, anger in the liver,
joy in the spleen, Sec. Bacon and Van Helmont seated them in the sto-
mach; Lecat in the nervous plexuses; other physiologists in the gang-
lions of the great sympathetic, Sec. But have they not confounded the
effect with the cause? the appetite with the passion to which it disposes?
The appetites, out of which the passions spring, reside in the organs
they suppose only instinctive determinations, whilst passion carries with
it the idea of intellectual exertion. Thus, the accumulation of semen in
the vesiculae which serve for its reservoirs, excites the venereal appetite,
quite distinct from the passion of love, though often its determining
cause. Animals have scarcely more than appetite, which differs as much
from passion as instinct from intelligence. However, the brain is not to
be considered as the primitive seat of the passions*, as is done by the
greater number of philosophers. Of all the feelings of man, the most
lasting, the most sacred, the most passionate, the least susceptible of in-
jury from all the prejudices of the social state, maternal love, is surely
not the result of any intellectual combination, of any cerebral action: it
is in the bowels (entrailles) its source lies : thence it springs, and all the
efforts of imagination cannot attain it for those who have not been blevss-
ed with a mother's name.

All passion springs from desire, and supposes a certain degree of exalta-
tion of the intellectual faculties. The shades of the passions are infi-
nite: they might be all arranged by a systematic scale; of which indif-
ference would be the lowest gradation, and maniacal rage the highest. A
man without passion, is as impossible to imagine, as a man without de-
sires ; yet we distinguish, as passionate, those whose will rises power-
fully towards one object earnestly longed for. In tne delirium of the
passions, we are for ever making unconsciously, false judgments, of which
the error is exaggeration. A man recovering from a seizure of fear, laughs
at the object of his terror. Look at the lover whose passion is extinct!
freed, at last, from the spell that enthralled him, all the perfections with
which his love had invested its object are vanished : the illusion has pass-
ed away; and he can almost believe that it is she who is no longer the
same, while himself alone is changed : like those maniacs who, on their
return to reason, wonder at the excesses of their delirium, and listen, in-
credulously, to the relation of their own actions. The ambitious man
feeds on imaginations of wealth and power. He who hates, exaggerates

* If we analyzed the passions carefully, it would be right to distinguish those which
are common to all men, which appertain to our physical wants and to our nature, from
certain caprices of the mind which have been honoured with the name of passion, as
Avarice, ambition, &c. which should be referred to kinds of mental derangement, and
classed as species, of monomania.

307

the defects of theobject of his hatred, and sees crimes in his slightest
faults.

The affections of the soul, or the passions, whether they come by the
sense, or some disposition of the vital organs favour their birth and
growth, may be ranged in two classes, according to their effects on their
economy. Some heighten organic activity ; such are joy, courage, hope,
and love; whilst others slacken the motions of life, as fear, grief, and
hatred. And others there are, that produce the two effects alternately,
or together. So ambition, anger, despair, pity, assuming, like the other
passions, an infinite variety of shades, according to the intensity of their
causes, individual constitution, age, sex, &c. at times increase, at times
abate, depress or exalt the vital action, and exalt or depress the power of
the organs.

The instances which establish the powerful influence of the passions on
the animal economy are too frequent to need reciting. Writers, in every
department furnish such as show that excess of pleasure, like excess of
pain, joy too lively or too sudden, as grief too deep and too unexpected,
may bring on the most fatul accidents and even death. Without collect-
ing in' this place* all the observations of the sort with which books swarm,
I shall content myself with referring to those who have brought together
the greatest number of facts under one point of view; as Haller, in his
Physiology; Tissot, in his Treatise on Diseases of the Nerves; Lecamus,
in his work on Diseases of the Mind; Bonnefoy, in a paper on the Pas-
sions of the Soul; inserted in the fifth volume of the Collection of Prizes,
adjudged by the Academy of Surgery.

The effects of the passions are not, for their uniformity, the less inex-
plicable. How, and why does anger give rise to madness, to suppres-
sion of urine, to sudden death ? How does fear determine paralysis, con-
vulsions, epilepsy, 8cc. ? Why does excessive joy, a sense of pleasure
carried to extremity, produce effects as fatal as sad and afflicting impres-
sions? In what way can violence of laughter lead to death ? Excess of
laughter killed the painter Zeuxis and the philosopher Chrysippus, ac-
cording to the relation of Pliny. The conversion of the reformed of the
Cevennes, under Louis XIV. was effected by binding them on a bench,
and tickling the soles of their feet, till overpowered by this torture, they
abjured their creed : many died in the convulsions and immoderate
laughterj which the tickling excited*. A hundred volumes would be in-
sufficient to detail all the effects of the passions on physical man ; how
many would it take to tell their history, in moral man, from their dark
origin, through all their stages of growth, in the infinite variety of their
characters* and in all their evanescent shades !

The inquiries of Physiology are directed to the functions that are car-
ried on in physical man, to the functions of life : the study of the nobler
parts of ourselves, of those wonderful faculties which place our kind
above all that have motion or life ; in a word the knowledge of moral and
intellectual man belongs to the science known by the name of metaphy-

* This instance, however, does not illustrate the influence of the passions on the vital
functions. It showsmerely the effects of irritation of the extremities of nerves upon the
functions of other nerves either of the same, or of a different order, which effects are
either produced by a direct medium of communication with the nerves first affected, or
then by means 01' the nervous centres. — Copland.

308

sics, or psychology, of analysis of the understanding, but better described
by that applied to it by the writers of our days, ideology. On this sci-
ence, you may consult with advantage, the philosophical works of Plato
and Aristotle, among the ancients ; of Bacon, Hobbes, Locke, Condillac,
Bonnet, Smith, Reid, Dugald, Stewart, Brown, Cabanis, and. Tracy,
among the moderns.

CLX. Of sleep and waking. The causes of excitation to which our
organs are exposed during waking, tend to increase progressively their
action ; the pulsations of the heart, for instance, are much more frequent
in the evening than in the morning, and this motion, gradually accelera-
ted, would soon be carried to a degree of activity incompatible with the
continuance of life, did not sleep daily temper this energy, and bring it
down to its due measure. Fever is occasioned by long continued want of
sleep, and in all acute diseases, the exacerbation comes on towards even-
ing, the night's sleep abates again the high excitation of power: but this
state of the animal economy, so salutary and so desirable in all sthenic
affections, is more injurious than useful in diseases, consisting chiefly in
extreme debility. Adynamy shows itself, almost always, in the morning,in
putrid fevers ; and petechiae, a symptom of extreme weakness, break out
during sleep. This state is, likewise favourable to the coining on and to
the progress of gangrene, and this is a pathological fact well ascertained.
In all the cases I have mentioned, sleep does not improve the condition
of the patients ; a thing easy to conceive, since it only adds to accidental
debility, the essential characteristic of the disease, weakness which is al-
so its principal characteristic.

Sleep, that momentary interruption in the communication of the senses
with outward objects, may be defined the repose of the organs of sense,
and of voluntary motion. During sleep, the inward or assimilating func-
tions are going on : digestion, absorption, circulation, respiration, secre-
tion, nutrition, are carried on; some as absorption and nutrition* with
more energy than during waking, whilst others are evidently slackened.
During sleep, the pulse is slower and weaker, inspiration is less frequent,
insensible perspiration, urine, and all other humours derived from the
blood, are separated in smaller quantity. Absorption is, on the contra-
ry, very active : hence the danger of falling asleep inithe midst of a noxi-
ous air. It is known that the marshy effluvia, which make the Com-
pagna di Roma so unhealthy, bring on, almost inevitably, intermittent
tevers, when the night is passed there, whilst travellers, who go through
•without stopping, are not affected by itf.

* Nutrition is evidently more active during1 sleep, in early life, especially in childhood;
and, in many constitutions and habits of body, it appears equally active, during this
state, through the middle stages of life ; but as soon as the period of decay approaches,
absorption appears to predominate, while on the contrary, nutrition gradually languishes
more and more, during sleep, as age advances. In the middle periods of existence it is
difficult to determine whether absorption or nutrition is augmented during this state :
the difference cannot always be correctly appreciated ; but we generally find that when
the one is increased the other is generally diminished, both functions being seldom aug-
mented or impaired at the same time. — Copland.

f Tins is quite as much the result of the low state of the nervous and vital energies
of the system during sleep. The vital powers at that time are not under the impression
of the excitements communicated through the medium of the nerves of sensation and
motion ; the operations, indeed, of this part of the nervous system are for a time suspend-
ed, and consequently the vital functions lose part of their energy, and are open to the

809

- The human body is a tolerable representation of the centripetal and
centrifugal powers of ancient physics. The motion of many of the sys-
tems which enter into its structure is directed from the centre to the cir-
cumference : it is a real exhalation that carries out the result of the per-
petual destruction of the organs ; such is the action of the heart, of the
arteries, and of all the secretory glands. Other actions, on the contrary,
take their direction from the circumference to the centre ; and it is by
their means that we are incessantly deriving from the food we take into
the digestive passages, from the air which penetrates the interior of the
lungs, and covers the surface of the body, the elements of its growth, and
repair. These two motions, in opposite directions, continually balance
each other, prevailing by turns, according to the age, the sex, the state of
sleep or waking. During sleep, the motions ten'd from the periphery to
the centre, (Hipp.) and if the organs that connect us with outward objects
are in repose, the inward parts are in stronger exertion. Somnus labor vi-
sceribus (Hipp.) A man, aged forty years, taken with a kind of imbecili-
ty, remained about a year and a half at the Hospital of St. Louis, for the
cure of some scrophulous glands : all that long time he remained con-
stantly in bed, sleeping five sixths of the day, tortured with devouring
hunger, and passing his short moments of waking in eating 5 his diges-
tion was always quick and easy; he kept up his plumpness, though the
muscular action was extremely languid, the pulse very weak and very
slow. In this man, who, to use the expression of Bordeu, lived under
the dominion of the stomach, the moral affections were limited to the de-
sire of food and of repose. Oppressed with irresistible sloth, it was ne-
ver without great difficulty that he could be brought to take the slight-
est exercise.

Waking may be looked upon as a state of effort and of considerable
expenditure of the sensitive and moving principle, by the organs of sen-
sation and of motion. This principle would have been soon exhausted
by this uninterrupted effusion, if long intervals of repose had not favoured
its restoration. This interruption in the exercise of the senses and of
voluntary motion, is of duration corresponding to that of their exertion.
I have already said, that there are functions of such essential importance
to life, that their organs could be allowed but short moments of repose^
but that these intervals are brought so close to each other, that their time
is equally divided between activity and repose. The functions which
keep up our connexion with outward objects, could not be without the

influence of such causes of disease as generally invade them during1 states of debility
and exhaustion, or when they are not otherwise acted on eitheir by external or internal
stimuli.

It may be justly asserted that the operations of the system languish in a degree pro.
pprtionate to that in which they are deprived of their natural excitements, whether these
excitements are food, air, exercise, amusement, 8cc. — whether they are coporeal or
mental — or whether they are external or internal with respect to their modes of exist-
ence, and to their manner of operation on the body. When, therefore, the system is
deprived of apart of these excitements, — of the influence of the mental operations, and
of the excitements of sensation and voluntary motion, as it is during1 sleep, its operations
are necessarily more languid and weak, and consequently it is more ready impressed by
many during- the waking state. The condition of the night air, in respect to tempera-
ture, and the concentration of the moisture and of the terrestrial exhalations in the low-
er regions of the atmosphere, especially in particular situations, also contribute to the
effect mentioned in the text. — Copland.

310

capacity of continuing, for a certain time, in a state of equal activity; for
it is easy to see how imperfect, relations interrupted at every moment,
would have been: their reposej which constitutes sleep, is of equal dura-
tion.

The duration of sleep is from a fourth to a third of the day: few sleep
less than six hours, or more than eight. Children, however, require
longer sleep; the more, the nearer they are to the period of their birth.
Old men, on the contrary, have short sleep, light, and broken; as if, says
Grimaud, according to Stahl's notions, children foresaw that in the long
career before them, there were time enough for performing, at leisure,
all the acts of life, while old men near to their end, felt the necessity of
hurrying the enjoyment of a good already about to escape.

If the sleep of a child is long, and deep, and still, it is the wonderful
activity of the assimilating functions that makes it so, and perhaps the
habit itself of sleep, in which he has passed the first nine months of his
life, or all the time before his birth. In advanced age, the internal func-
tions grow languid; their organs no longer engage the action of the prin-
ciple of life; and the brain is moreover so crowded with ideas, that it is
almost always kept awake by them. Carnivorous animals sleep longer
than graminivorous, because during waking they are more in motion,
and perhaps, too, because the animal substances on which they subsist,
yielding them more nutritious particles, from the same bulk, they have
need of less time for devouring their food and providing for their sub-
sistence*.

Sleep is a state essentially different from death, to which some authors
have erroneously likened itf. It merely suspends that portion of life>
which serves to keep up with outward objects an intercourse necessary
to our existence. One may say, that sleep and waking call each other,
and are of mutual necessity. The organs of sense and motion, weary of
acting, rest ; but there are many circumstances favouring this cessation
of their activity. A continual excitation of the organs of sense would
keep them continually awake; the removal of the material causes of our
sensations tends, therefore, to plunge us into the arms of sleep: where-
fore we indulge in it more voluptuously in the gloom and the stillness of
nightj:. Our organs fall asleep one after the other; the smell, the taste,
and the sight are already at rest, when tke hearing and the touch still
send up faint impressions. The perceptions, awhile confused, in the end
disappear; the internal senses cease acting; as well as the muscles al-
lotted to voluntary motion, whose action is entirely subject to that of the
brain.

* Probably, their more powerful digestion of a more nutritious food, bringing into
the system a more sudden accession of blood, oppresses them with sleep : — a sleep and
a fullness of blood required to recruit the powers that have been exhausted by the la-
borious quest of food, and by the long continued endurance of hunger.

Animal food, according to the extent to which it is indulged in, or the length of the
intervals between its use, produces either absolute or relative vascular plethora, both
which states dispose to sleep.

•}- To say that sleep is the image of death, that vegetables sleep always, is to use an
inaccurate and unmeaning expression. How can plants, without brain or nerves, with-
but organs of sense, motion, or voice, sleep ; when sleep is nothing but the repose of
these organs ?

t The tissue of the eye-lids is not so opake but we may distinguish through them light
from darkness : accordingly, a lighted torch in the room, hinders us from sleeping. For
the same reason, day succeeding to night awakens us.

311

Sleep, is a state, if not altogether passive, in which, at least, the activity
of most of the organs, is remarkably diminished, and that of some of
them are completely suspended. It is erroneously then, that some au-
thors have viewed it as an active phenomenon, and a function of the
living economy: it is only a mode or manner of being. It is to no pur-
pose they have maintained, that to sleep required some measure of
strength. Excessive fatigue hinders sleep, merely by a sense of pain in.
all the muscles, a pain that excites anew the action of the brain, which
it keeps awake, till it is itself overpowered by sleep.

It has been attempted to show the proximate cause of sleep. Some
have said that it depends on the collapse of the lamina of the cerebellum,
which, as they conceive, are in a state of erection during waking; and
they argue from the experiment in which, by compressing the cerebel-
lum of a living animal, sleep is immediately brought on. This sleep,
like that produced by compression of any other part of the cerebral
mass, is really a state of disease; and no more natural than apoplexy.
Others, conceiving sleep, no doubt, analogous to this affection, ascribe
it to the collection of humours upon the brain during waking. This or-
gan, say they, compressed by the blood which obstructs its vessels, falls
into a state of real stupor. An opinion as unsupported as the other. As
long as the humours flow in abundance towards the brain, they keep up
in it an excitement winch is altogether unfavourable to sleep. Do we
not know, that it is enough that the brain be strongly occupied by its
thoughts, or vividly affected in anyway, to repel sleep? Coffee, spiritu-
ous liquors, in small quantities, will produce sleeplessness, by exciting
the force of circulation, and determining towards the brain a more con-
siderable afflux of blood. All, on the other hand, that may divert this
fluid towards another organ, as copious bleedings, pediluvium, purges,
digestion, copulation, severe cold, or whatever diminishes the force with
which it is driven towards it, as inebriation, general debility, tends power-
fully to promote sleep. In like manner, it is observed, that while it lasts,
the cerebral mass collapses: a sign that the flow of blood into it is re-
markably lessened.

The organs of the senses, laid asleep, in succession, awake in the same
manner. Sounds and light produce impressions, confused at first, on the
eyes and ears; in a little time these sensations grow distinct; we smell,
we taste, we judge of bodies by the touch. The organs of motion prepare
for entering into action, and begin to act, at the direction of the will*.
The causes of waking operate by determining a greater flow of blood
into the brain : they include all that can affect the senses, as the return
of light and of noise with the rising of the sun; at times, they act within
us. Thus, urine, fecal matter, other fluids accumulated in their reser-
voirs, irritate them, and send up, towards the brain, an agitation which
assists in dispelling slumber. Habit, too, acts upon this phenomenon,
as on all those of the nervous and sensitive system, with most remarka-
ble influence. There are many that sleep soundly amidst noises which,
at first, kept them painfully awake. Whatever need he may have of
longer repose, a man that has fixed the daily hour of his awaking, will
awake every morning to his hour. It is as much under the controul of
the will. It is enough to will it strongly, and we can awake at any hour
we choose.

* See tbp CHAPTER on Motion, Art. CLXXII.

312

CLXI. Of dreams and somnambulism. Although sleep implies the per-
fect repose of the organs of sensation and of motion, some of these or-
gans persist in their activity*; which obliges us to acknowledge inter-
mediate states between sleep and waking, real mixed situations, which
belong, more or less, to one or to the other. Let us suppose, for instance,
that the imagination reproduces, in the brain, sensations it has formerly
known, the intellect works, associates, and combines ideas, often dis-
cordant, and sometimes natural, brings forth monsters, horrible, fantastic,
or ridiculous ;. raises joy, hope, grief, surprise, or terror ; and all these
fancies, all these emotions, are recollected more or less distinctly, when
we are again awake, so as to allow no doubt but that the brain has been
really in action, during the repose of the organs of sense and motion.
Dreams is the name given to these phenomena. Sometimes we speak
in sleep, and this brings us a little nearer to the state of waking, since
to the action of the brain is added that of the organs of speech. Finally,
all the relative functions are capable of action, excepting the outward
senses. The brain acts, and determines the action of the organs of mo-
tion or speech, only in consequence of former impressions ; and this state,
which differs from waking, only by the inaction of the senses, is called
somnambulism.

On this head we meet with surprising relations. Somnambulists have
been seen to get up, dress, go out of the house, opening and shutting
carefully all the doors, dig, draw water, hold rational and connected dis-
course, go to bed again, and awake without any recollection of what
they had said and done in their sleep. This state is always very perilous.
For as they proceed entirely upon former impressions, somnambulists
have no warning from their senses, of the dangers they are near. Ac-
cordingly, they are often seen throwing themselves out at a window, or
falling from roofs, on which they have got up, without being on that ac-
count more dexterous in balancing themselves there, as the vulgar believe
in their fondness for the marvellous.

Sometimes, one organ of sense remains open to impression, and then
you can direct, at pleasure, the intellectual action. Thus, you will make
him that talks in his sleep, speak on what subject you choose, and steal
from him the confession of his most secret thoughts. This fact may be
cited in proof of the errors of the senses, "and of the need there is to cor-
rect them by one another.

The conditions of the organs influences the subject of the dreams. The
superabundance of the seminal fluid provokes libidinous dreams; those
labouring under pituitary cachexies will dream of objects of a hue like
that of their fluids. The hydropic dreams of waters and fountains,
whilst he who is suffering with an inflammatory affection, sees all things
tinged red, that is, of the colour of blood, the predominant fluid.

Difficult digestion disturbs sleep. If the stomach, over-filled with food,
hinders the falling of the diaphragm, the chest dilates with difficulty, the
blood, which flows through the. lungs, stagnates in the right cavities of
the heart, and a painful sensation comes on, as if an enormous weight lay

* The individual who even enjoys the most profound sleep, seldom wakens in the
same position as that^in which he was at the moment of falling asleep : it is changed
frequently during the time, owing, perhaps, to certain obscure sensations giving rise
to movements analogous to those of the foetus in utero, although more perfect, and
seemingly influenced by habit, &c.

313

upon the chest, and were on the point of producing suffocation: we awake
with a start, to escape from such urgent danger: this is what we call
night-mare, an affection that may arise from other causes, hydrothorax,
for instance, but which always depends on the difficult passage of blood
through the lungs.

The intellectual faculties which act in dreams, may lead us to certain
orders of ideas, which we have not been able to compass while awake.

Thus, mathematicians have accomplished in sleep, the most complex
calculations, and resolved the most difficult problems. It is easily under-
stood, how, in the sleep of the outward senses, the sensitive centre must
be given up altogether to the combination of ideas in which it must work
with more energy. It is seldom that the action of imagination on the
genital organs, during waking, goes the length of producing emission:
nothing is more common in sleep.

The human species is not the only one, that in sleep is subject to agita-
tions, which are generally comprehended under the name of dreams:
they occur in animals, and most in those whose nature is most irritable
and sensible. Thus, the clog and horse dream more than the ruminating
kinds; the one barks, and the other neighs in sleep. Cows that are
suckling their calves, utter faint lowings ; bulls and rams seem goaded
by desires, which they express especially, by peculiar motions of their
lips.

After what has l^een said of sleep and dreams, it will not be difficult to
explain, why there is so little refreshment of the powers, from sleep that
is harassed by uneasy dreams. We often awake, exceedingly fatigued
by the distress of imaginary dangers, and the efforts we have made to
escape them.

We have seen the relations of man, with the external world, esta-
blished by means of peculiar organs, which, through the intervention of
the nerves, all centre in one, the chief and essential seat of the functions
of which this chapter treats. As the phenomena of the sensations are
brought about by the intervention of an unknown agent, and as like
those of electricity and magnetism, they appear not to be subject to the
ordinary laws of matter and motion, they have thrown open the widest
field to the conjectures of ignorance, and the inventions of quackery. It
is for their explanation, that the greatest abundance of theories, and the
wildest, have been devised.

Ott the 23d of December, it is not said in what year, a physician of
Lyons, M. Petetin, was called in to a young lady of nineteen, sanguine
and robust. She was cataleptic. The doctor employed various reme-
dies; and among others, one day bethought himself of pushing over the
patient on her pillow: he himself fell with her, half stooping upon the
bed, and this led him to the " discovery of the transport of the senses in
the epigastrium, to the extremities of the fingers and of the toes." I use
his own pompous and barbarous expressions, in announcing his discovery.
Our doctor goes on to tell with all gravity, how putting » bun on the
epigastrium of the patient, she perceived the taste, which was followed
by motions of deglutition : if his word is to be taken, hearing, smell,
taste, sight, and touch, were all there : the outward senses, being, for
the time, completely laid asleep. To give an air of credibility to the mat-
ter, he adds, that she saw the inside of her body, guessed what was in
the pockets of bystanders, made no mistake in the money in their purses;
but the miracle was over, the moment they lapped the objects in a silk

2R

314

stuff, a coat of wax, or interposed any other non-conductor. Finally,
to put to proof the wfcole power of faith in his readers, M. Petetin ex-
claims, « Oh prodigy beyond conception ! was a thought formed in the
brain without any sign of it in words, the patient was instantly acquaint-
ed with it"*. Further details of so incredible a story would be altoge-
ther superfluous.

I should not have disturbed the book of M. Petetin, from its peaceful
slumber, among the innumerable pamphlets which Mesmerism has
brought into the world, if a writer on physiology had not been the dupe
of this mystification, and had not proceeded from it, to write a long chap-
ter on the metastases of sensibility.

If we should be so unfortunate as to be reproached by the lovers of the
marvellous, with pushing scepticism too far, we must make answer, that
M. Petetin is the sole witness of his miracle ; that it is impossible, from
his relation, to know when or on whom the prodigy took place 5 and that
this zealot of magnetism might have invented this story to confound the
unbelievers who ventured to turn into ridicule, his system of electricity
and of the human bodv.

CHAPTER VIII.

OF MOTION.

CLXII. THIS Chapter will treat only of the motions performed by the
muscles under the influence of the will ; they are called muscles of loco-
motion, as it is by means of them, that the body changes its situation,
moves from one spot to another, a\oicls or seeks surrounding objects,
draws them towards itself, grasps them, or repels them. The internal,
involuntary, and organic motions, by means of which each function is per-
formed, have already been investigated separately.

The organs of motion may be distinguished into active and fiassajj& the
former are the muscles, the latter the bones, and all the parts by which
they are articulated. In fact, when in consequence of an impression re-
ceived by the organs of sense, we wish to approach towards the object
that produced it, or to withdraw from it, the muscular organs, called in-
to action by the brain, contract $ while the bones, which obey this action,
perform only a secondary part, are passive, and may be looked upon as
levers absolutely inert.

The muscles consist of bundles of fibres, always, to a certain degree,
red in man : ihis colour, however, is not essential to them, since it may
be removed, and the muscular tissue blanched by maceration, or by re-
peated washing.

Whatever may be the situation, the length, the breadth, the thickness,
the form, or the direction of a muscle, it is formed of a collection of se-

* Electricite animate, 1 vol. 8vo. Lyon, 81

315

veral fasciculi of fibres, enveloped in a cellular sheath similar to that
which covers the muscle itself, and separates it from the surrounding
parts. Each fasciculus is formed of the union of a multitude of fibres,
so delicate, that anatomy cannot reduce them to their ultimate division,
and that the smallest distinguishable fibre is still formed by the juxta po-
sition of numerous fibrilhe of incalculable minuteness. As the last divi-
sions of the muscular fibre completely elude our means of investigation,
it would be very absurd to attempt to explain their minute structure, and,
after the example of Muys, to write a voluminous work on this obscure
part of physiology. Shall we say, with the above author, that each dis-
tinguishable fibre is composed of three fibrillse progressively decreasing
in size; with Leeuwenhoek, that the diameter of this elementary fibre is
only the hundred thousandth part of a grain of sand ; with Swamrfter-
dam, de Heyde, Cowper, Ruysch, and Borelli, that this primitive fibre
consists of a series of globular, rhomboidal molecules; with Lecat, that
it is nervous; with Vieussens and Willis, that it is formed by the extreme
ramifications of arteries; with others, that it is cellular, tomeritous, 8cc.
How is it possible to speak, with any degree of certainty, of the nature
of the parts of a whole, which, from its extreme minuteness, eludes our
most accurate investigations. To explain the phenomena of muscular
action, it is inefficient to conceive each fibre as formed of a series of mo-
lecules of a peculiar nature, united together by some unknown medium,
whether that be oil, gluten, or any other substance, but whose cohesion
is manifestly kept up by the vital power, since the muscles yield, after
death, to efforts by which, during life, they would not have been torn 5
and such is their tenacity, that they are very seldom ruptured*.

These fibres, which, when irritated, possess, in the highest degree, the
power of shortening themselves — of contracting, however minute one may
suppose them, are supplied with vessels and nerves. In fact, though they
are neither vascular nor nervous, as may be readily ascertained by com-
paring the vessels and nerves which enter into the structure of the mus-
cles, with that of these organs, and by attending to the difference of their
properties; each fibre receives^ the power of contracting, from the blood
brought to it by the arteries, and from the fluid transmitted from the
brain, along the nerves. A cellular sheath surrounds these fibrillae (and
the nerves and vessels perhaps terminate within it)f, others unite them

* " M. BATTEH, by the assistance of his powerful microscope, discovered muscular
fibres to be chains of globules, and he conceived that they may be constructed from the
globules of fibrine arranged in lines. — Copland.

\ The majority of anatomists suppose that the muscular fibre itself is beyond the
circuit of the circulation, and this appears in some points of view the correct opinion, if
we attend to the form and size of the fibres, and to their connexions with the cellular
tissue ; but although we may grant that the red globules of the blood do not circulate
through the muscular fibres themselves, and that these globules pervade only the capil-
laries of the connecting cellular substance, still we must allow that they are formed and
afterwards supported, either by the vessels conveying red blood, assimilation taking
place, in the manner of a deposit from them, without any continuity of texture, or by
the medium of a direct communication and admixture of a particular series of capillary
terminations of vessels with the muscular fibres, into which the red globules cannot
enter owing to the great tenuity of these capillaries. If we choose the former alter-
native, which appears, however, the least probable, we may conceive that the nervous
terminations, in muscular parts, soften into an invisible pulp, and unite intimately with
the capillary vessels, and with the cellular texture, which connects the individual fibres;
and that the chain of globules, of which the fibres are composed, being acted on by the
influence resulting from the action of the nervous on the vascular terminations in the

316

together ; the fasciculi of fibres are inclosed in common sheaths, and
these unite, in the same manner, into masses varying in size, and the
union of which forms the muscles; fat seldom accumulates in the cellu-
lar tissue which connects together the smallest fasciculi; it collects, in
small quantity, in the interstices of the more considerable fasciculi; last-
ly, it is in rather greater quantity, around the muscle itself. A lympha-
tic and aqueous vapour fills these cells, maintains the suppleness of the
tissue, and promotes the action of the organ, which a fluid 01 more con-
sistence would have impeded.

The greater number of muscles terminate in bodies, in general round,
of a brilliant white colour, that forms a striking contrast with the red co-
lour of the muscular flesh, in which one of their extremities is imbedded,
while the other extremity is attached to the bone and is lost in the peri-
osteum, though the tendons are quite distinct from it. The tendons are
formed by a collection of longitudinal and parallel fibres ; their structure
is more compact than that of the muscles, they are harder and apparently
receive neither nerves nor vessels; they consequently possess but a very
inferior degree of vitality; hence they are frequently ruptured by the ac-
tion of the muscles. The muscular fibres are implanted on the surface of
the tendinous cords, without being continuous with the filaments forming
the latter; they join them in a different manner, and at angles more or
less obtuse.

The tendons, in penetrating into the fleshy part of the muscles, expand,
become thinner, and form thus the internal aponeuroses. The external
aponeuroses, independent of the tendons, though the same in structure,
differ from them only in the thinness and greater surface of the planes
formed by their fibres. At one time, they cover a portion of the muscle
to which they belong; at another, they surround the whole limb, furnish-
ing points of insertion to the muscles; they prevent the muscles and their
tendinous cords from being displaced; in a manner, direct their action,
and increase their power, in the same way as a moderately tight girdle
adds to the power of an athletic.

enveloping cellular snbstance, experience in consequence a contraction in proportion
to the nervous excitement. In this case we must suppose a certain influence to emanate
from the connecting medium to the muscular fibre, without any other communication
than that of contact or contiguity. If, on the other hand, we adopt the latter alternative,
and believe that an order of capillary vessels of great tenuity enter into the structure
of the muscular fibre, and that the voluntary and organic nerves which blend with the
capillary vessels also proceed to, and terminate in this structure, we may further con-
clude— and, indeed, the conclusion will necessarily follow, — that the muscular fibre is
composed of a certain order of capillary vessels, and of the terminations of the ganglial
nerves (which nerves we must suppose to supply, and to terminate with these capilla-
ries, as they are found to envelope, and to be distributed to the muscular and internal
coats of the larger ramifications or trunks of the vessels whence the capillaries are sent
off) with the extremities of voluntary nerves which are so abundantly supplied to mus-
cular parts. Having considered that the muscular fibre is formed from this combination,
me have not data whence we can farther infer its intimate nature, or the extent to
which each of these systems contributes to its formation in the voluntary muscles. We
may suppose, however, that the functions of these textures differ according as either of
the constituents which we have now assigned them predominate in their constitution,
(see Note at p. 17.) The observations of Mr. Bauer, we may state, seem to support the
view we have now offered. — Copland.

See APPENDIX, Note F F, for further observations on this subject, and on Irrita-
bility.

.317

We cannot admit, with Pouteau, that the muscles of the limbs, though
applied to the bones by aponeurotic coverings, can become displaced, so
as to form herniae. When they contract in a wrong1 position, some fib-
rillce are torn, and this gives rise to most of those momentary and very
sharp pains called cramp. I have, at present, before me, the case of a
young girl, in whom the aponeurosis of the leg, exposed in conse-
quence of an extensive ulceration, exfoliated from the middle and fore
part of the limb to the instep. This exfoliation was accompanied by a
displacement of the tibialis anticus of the extensors of the toes; the leg
is become deformed, the motions of extension of the foot and toes are per-
formed with difficulty, and will soon become impossible, when the exfoli-
ation of the tendons follows that of the aponeurosis which protected them
from the air.

CLXIII. When a muscle contracts, its fibres are corrugated trans-
versely, its extremities are brought nearer to each other, then recede, and
again approach towards one another. These undulatory oscillations,
which are very rapid, are followed by a slighter degree of agitation ; the
body of the muscle, swollen and hardened in its decurtation, has acted on
the tendon in which it terminates ; the bone to which the latter is connect-
ed is set in motion, unless other agents, more powerful than the muscle
which is in action, prevent its yielding to that impulse. Such are the
phenomena exhibited by the muscles exposed in a living animal or in
man, when their contractions are brought on by the application of a sti-
mulus. But these contractions, determined by external causes, are never
so strong or instantaneous, as those which are determined by the will, in
a powerful arid sudden manner. When an athletic man reduced by ill-
ness, powerfully contracts the biceps muscle of the arm, this muscle is
seen to swell suddenly, to stiffen and to continue motionless in that state
of contraction, as long as the cerebral influence, or the act of the will,
which determines it, lasts.

Though the muscles manifestly swell in contracting, and though the
limbs are confined by the ligatures applied round them, the whole bulk
of the contractile organ diminishes: it loses in length, more than it gains
in thickness This is proved by Glisson's experiment which consists in
immersing the arm in a vessel filled with a fluid, which sinks when the
muscles act. We cannot, however, estimate the diminution of bulk, by
the degree in which the fluid sinks, since that effect is, in part, owing to
the collapse of the layers of the adipose tissue, which is compressed in the
muscular interstices.

A sound state of the vessels and nerves distributed to muscles is indis-
pensible to their contraction. If the free circulation of the blood or of
the nervous fluid is prevented, by tying the arteries or nerves ; if the re-
turn of the blood, along the veins, is prevented, by applying a ligature to
these vessels, the muscles will be completely palsied. By dividing or ty-
ing the nerves, the action of the muscles to which they are distributed,
is suddenly interrupted. The same effect may be produced by intercept-
ing the course of the arterial blood, though in a less rapid and instanta-
neous manner; and it is very remarkable, that it is equally necessary that
the veins should be as sound as the arteries, to enable muscular action to
take place. Kaaw Boerhaave ascertained, by actual experiment, that when
a ligature is applied to the vena cava, above the lilacs, paralysis of
the lower extremities is brought on, as when the aorta is tied, as was

318

done by Steno in the same situation*. And this is a further proof of what
we have said elsewhere, of the stupifying qualities of the blood which
flows in the veins.

The irritability of the muscles destined to voluntary motions is propor-
tioned to the size and number of the nerves and arteries which are
distributed to their tissuef. The tongue, which of all the contractile
organs receives the greatest number of cerebral nerves, is, likewise, that
which, of all those under the controul of the will, has most extent, most
freedom, and most variety of motions!. The muscles of the larynx, and
the intercostals, receive nearly as many, considering the smallness of
these parts§.

CLXIV. Of all the hypothesis applied to the explanation of the phe-
nomena of muscular contraction, that appears to me the most ingenious
and the most probable, which makes it to depend on the combinations
of hydrogen, of carbon, of azote, and other combustible substances in
the fleshy part of the muscle, with the oxygen conveyed with the blood
by the arteries.

To effect this combination, it is necessary, not only that the muscle be
supplied with arterial blood, and that oxygen come in contact with the
substances which it is tooxydize, but it is required, that a stream of nerv-
ous fluid should penetrate through the tissue of the muscle, and determine
the decompositions which take place, as the electrical spark gives rise to
formation of water by the combination of the two gases of which it con-
sists. According to this theory, first proposed by Girtanner, all the
changes which take place, during the contraction of a muscle, theturges-
cence, the decurtation and the induration of its tissue, its change of tem-
perature depend on this reciprocal action of the elements of the muscular
fibre, and of the oxygen of arterial blood.

Muscular flesh is harder, firmer, and more oxydized, according as the
animaltakes much exercise. We well know, what a difference there is,
between the flesh of wild and of the domestic animals ; between the flesh
of our common fowl and that of birds accustomed to remain long on the

* Ligature of the aorta may be conceived to produce paralysis, owing chiefly to the
stop it puts to the circulation of arterial blood in that part of the spinal cord, and in the
neurilema of the nerves, below where the ligature is placed.

I See APPENDIX, Note F F.

$ It is scarcely necessary to repeat, that I am not speaking of those motions, more or
less involuntary, performed by muscles which receive tiie nerves, in part or wholly,
from the great sympathetics. Though the particular nature of these nerves has a re-
markable influence on the organs to which they are distributed, we find that the general
rule is almost without exception, for the heart and diaphragm which hold the first rank
among the parts endowed with irratibility, receive a considerable number of vessels and
nerves. — Authur's Note.

§ The disposition of the muscles to contract is different from, and even opposite to,
their energy of contraction. The feeble muscles of an hysterical female contract so
readily and" so frequently from the slightest irritation, as nearly to appear involuntary
in their actions ; while, on the contrary, the powerful muscles of the athlet act only
from energetic stimuli and from fully expressed volition. Thus we observe in feeble in-
dividuals a certain mobility of muscular parts and organs, which does not exist in the
robust, as if the irritability of such parts were excited with a facility in proportion to
the deficiency of energetic action. The disposition of muscles to contract differs also
according to the age of the animal, and it bears even some relation to organization of
the muscle itself. — Copland.

See APPENDIX, Note F F, for remarks on the period at which the voluntary muscles
are formed, find on their appearances and constitution, at the different periods of life.

319

wing; in the former, it is white, tender and delicate, while, in the latter,
it is tough, stringy, dark-coloured, carbonaceous, and of a very strong-
smell. Respiration, of which the principal use is to impregnate arterial
blood* with the oxygen necessary to the contractions of the muscular
fibre, is more complete, decomposes the greater quantity of atmospheri-
cal air, in those animals that are naturally destined to most exertion.
Those birds which support themselves in the air by powerful and fre-
quent motions, have likewise, the most active respiration. Athletes, who
astonish us by the developement of their muscular organs, and by the
powerful efforts of which they are capable, all have a very ample chest,
a powerful voice, and very capacious lungsf. In running, as there is a
considerable consumption of the principle of motion, we pant, that is,
we breathe in a hurried manner, that there may be the. greatest possible
quantity of blood oxydized to perform the contractions necessary to the
exercise of running.

CLXV. Of the preponderance of the flexors over the extensors\. The ex-
tensor muscles are, generally, weaker than the flexors; hence the most
natural position, that in which all the powers are naturally in equilibrio,
that which our limbs assume during sleep, when the will ceases to deter-
mine the vital influx to the parts under its controul, that in which we can
continue longest without fatigue, is a medium between flexion and exten-
sion, a real state of semi-flexion.

Attempts have been made to discover the cause of this preponderance
of the flexor muscles over their antagonists. According to Borelli, the
flexors being shorter than the extensors of the same articulation, and con-
tracting equally^, the former must occasion a more extensive motion of
the limbs, and determine them towards a state of flexion. But it is, in
the first place, incorrect to say, that the flexors are shorter than the ex-
tensors; and, in the next place, if we are to estimate, by the length of a
muscle, the extent of motion that may be produced by its action, we ought
not to measure the whole of the fleshy part, nor to include in the calcula-
tion, the tendinous cord which terminates it, but UTconsider the length
of its fibres, on which depends entirely the extent of motion produced by
its contractions.

The degree of decurtation of which a muscle is capable, is always pro-
portioned to the length of its fleshy fibres, as is the power of contraction
to the number of the fibres. Now, if the fibres of the flexors are in greater
number than those of the extensors, it follows as a necessary conse-
quence, that the limbs will be brought into a state of flexion, when
the principle of motion shall be distributed to them in an equal quantity^
and even though the number of fibres should be the same in the flex-

* See APPENDIX, Note W.

f I never saw a very strong1 man that had not broad shoulders, which indicates a con-
siderable developement of the cavity of respiration. If there be individuals that seem
to be exceptions to this general law, it is that by frequent exercise, and by a laborious
life, they have increased the natural power of their muscles. This increase is seldom
universal, but almost always limited to certain parts which have been most employed ;
as the arms, the legs, or the shoulders. — Author's Note.

t The theory of the preponderance of the flexors is entirely my own, and was first
proposed by me, in the collection of Memoirs of the Medical Society of Paris, for the
year VII. of the Republic (1799.)— Author's JVote.

§ Musculi flexores ejusdem articuli breviores sunt extensoribus, et utrique jcque con-
trabuntur Prop. 180, de motu animalium.

320

ftrs and extensors, the limbs would still be in a state of flexion, if the
fibres of the former being longer, they made the parts move through a
greater space.

*tf we examine the different parts of the body, the articulations of the
limbs, and especially of the knee, the knowledge of which is of the high-
est importance in understanding the theory of standing, it will be seen
that the flexor muscles exceed the extensors, in the number and length
of their fleshy fibres. If we compare the biceps cruris, the semi tendi-
nosus, the serni membranosus,the rcctus internus, the sartorius, the ge-
melli, the plantaris, and the popliteus, which all concur in the flexion of
the leg, to the triceps cruris and to the rectus, which extend the leg, we
shall readily understand that the fibres of these last are much shorter, and
in smaller number. Those of the sartorius and rectus internus are the
longest of all the muscles employed in voluntary motion ; the fibres of
the posterior muscles of the limb are not inferior in length to the fibres
of the muscles at the fore part.

Besides, the flexor muscles are inserted into the bones which they are
to move farther from their centre of motion. In fact, if the insertion of
the semi membranosus is situated nearly at the same height, the sartorius,
the rectus internus, the semi tendinosus, the biceps, and the popliteus,
are inserted lower than the extensors of the leg. But this difference is
particularly observable in the plantaris and gemelli, which terminate at
the greatest possible distance from the centre of motion, and which act
with a very long lever*; lastly most of these muscles depart much more
than the extensors, from a parallel direction to the bones of the leg. We
all know the curved line of the course of the sartorius, of the rectus in-
ternus, and semi tendinosus, by which the angle of their insertion becomes
more favourable.

The flexor muscles which, on their being first called into action, are
nearly parallel to the levers which they are to move, tend to become
perpendicular to them, in proportion as the motion of flexon is carried on.
Thus, the brachialis, the biceps brachii, and the supinator longus, the
main line of direction of which is nearly parallel to that of the bones of
the fore arm, when the flexion of this limb commences, become oblique,
then perpendicular to this bone, and at last form with it the angle most
favourable their action. The same applies to the flexors of the leg; the
angle of their insertion becomes greater the more it bends on the thigh.
The extensors, on the contrary, are in the most favourable state for ac-
tion, at the moment when their contraction begins, in proportion as the ex-
tension goes on, they have a tendency to become parallel to the levers
which they sei in motion; their action even ceases before the parallelism
is complete, at the elbow by the resistance of the olecranon, and at the
knee by the numerous ligaments and by the tendons situated towards the
posterior part of the articulation.

The flexor muscles have, therefore, fibres of greater length and more
numerous than those of the extensors. They are inserted into the bones,

* We may, in this respect, compare the gemelli to the supinator longus, the use of
which is not limited, as was shown by Heister, to the supination of the hand ; but which
is, likewise, a flexor of the fore arm, and acts the more powerfully, as its inferior insertion
is at a greater distance from the elbow joint, and as its fibres are the longest of all those,
of the muscles of the upper extremity.— Copland,

321-

at a greater distance from the centre of their motion, at an angle less
acute, and which increases in size, as the limbs bend. The union of
these causes gives to the limbs their superior power, and the greater
range of motion in these muscles, is a consequence of the arrangement
of the articulating surfaces, which almost all incline towards the side of
flexion.

This preponderance of the flexor muscles, varies according to the dif-
ferent periods of life ; in the foetus, the parts are all bent very consider-
ably; this convolution of the young animal may be perceived from the
earliest period of gestation, when the embryo, of the size of a French
bean, and suspended by the umbilical cord, floats in the midst of the liquor
amnii, in a cavity of which it is more and more confined, as it approaches
to the period of its birth. This excessive flexion of the parts, which was
required to enable the produce of conception to accomodate itself to the
elliptical shape of the uterus, concurs in giving to the muscles which pro-
duce it, the superiority which they retain during the remainder of their
life. The new-born child preserves, in a very remarkable manner, the
habits of gestation ; but, in proportion as it grows, it straightens its body,
and, by frequent attempts to stretch itself, shows that a just proportion is
about to take place between the muscular powers. When the child be-
comes capable of standing erect, abandoned to its own powers, all its parts
are in a state of semi flexion, it staggers and is unsteady on its feet. To-
wards the middle of life, the preponderance of the flexors over the ex-
tensors, becomes less apparent; a man enjoys fully and completely his
power and locomotion; but, as he advances in years, this power forsakes
him; the extensor muscles gradually return to the state of comparative
debility of infancy, and become incapable of supporting the body, in a
fixed and permanent manner.

CLXVI. The state of our limbs, during sleep, approaches to that of
the foetus, which according to Buffon, may be considered to be in a pro-
found slumber. The cessation of sleep is attended in man, as well as in
most animals, by frequent stretchings. We extend our limbs forcibly,
to give to the extensors, the tone which they require during the state
of waking*. — Barthez accounts, in the same way, for the manner in
which the cock announces his waking, by crowing and flapping his
wings.

It may happen in consequence of a morbid determination of the vital
principle, that our limbs may remain in a state of extension during sleep.
Hence Hippocrates recommends, that the state of the limbs be carefully
attended to, while the patient sleeps, for, as he observes, the farther that
condition is from the natural state, the greater the danger to be appre-
hended of the patient's life. In certain nervous diseases characterized
by a manifest aberration in the distribution of the vital power, a continued
state of extension must be considered a symptom highly dangerous ; I
have had several times occasion to observe, that in cases of wounds at-
tended with convulsions and tetanus, these alarming affections were an-
nounced by the permanent extension of the limbs during sleep, before a

* Haller thinks, that these extensions are intended to relieve the uneasy sensations
occasioned by a long continued flexion, J\nnc quidem homines et animalia extendunt artus
quodiis fere con/lexis dormiant, etex eo pei^petuo situ, in musculis sensus incommodes oriatur,
quern extensione t ollunt, (phenomena ejcpergiscentium,} Elementa-physiologx, torn. V. p. 621,

2 S

322

difficulty of moving the jaw could give rise to any apprehension of their
approach.

Disease and excesses of all kinds, occasion in the extensor muscles a
relative weakness that is very remarkable, hence we see convalescents, and
those who have been addicted to voluptuousness, walk with bending knees,
the more so as their debility is greater, and as the force of the extensors
is more completely exhausted. The flexion of the knees is then limited
by that condition in which the tendons of the extensors of the leg acton
the tibia, at an angle sufficiently great to make up for their diminished
energy. There exists a condition of the animal economy, in which all
the muscular organs appear wearied with exertion, and the limbs assume
indifferently any position. In this state, which is always a very serious one,
as it'indicates an almost complete want of action in a system of organs
whose functions are absolutely essential to life, a state to which physici-
ans have given the name of prostration*, the limbs if unsupported, fall of
their own weight, as if they were palsied; the trunk is motionless, and
supine. The patient is incapable of changing his attitude, and yielding
to the weight of his body, sinks on the inclined plane formed by the bed,
and seems very heavy to those who may attempt to raise him, because
from his helplessness, he requires to be moved as an inert substance.

* It is from a knowledge of the strength of his patient, that the physician, in the treat-
ment of disease, deduces the most instructive indications. It seems to me, that we ought
to endeavour to characterize, by specific terms, the different states of animal adynamia
in different diseases. Our language, less fruitful in imagery than the ancient languages,
will not easily furnish these characteristic denominations, so useful in a science which
should paint objects in their truest colours, in terms most approaching to nature. It will,
therefore, be necessary to have recourse to the Greek and Latin languages, and perhaps
to give the preference to the latter, which is generally understood by those who prac-
tise the art of healing. The application of this principle to the dirk-rent kinds of fever,
will^rove its utility, and will, doubtless, be an inducement to extend it to all the classes
of morbid derangements.

In febre infhimmatoria sen synocho simplici (angeiotenicu) Opp-ressio virium.

In febre biliosa sen ardente (meningo-gastrica.) Fracturu virium.

In febre pituitosa, seu morbo mucoso (aclenomeningea) Languor virium.

In febre putrida (adynamica) Prosiratio viriitm.

In trebribus malignis seu atactis Jltaxia virium.

In febre pestilentiali (adeno-ncrvosa) Sideratio virium.

The first term which is easily turned into French, expresses, with much precision, that
condition in which the living system, far from being deficient in strength, is encumbered
by its excess, and is oppressed by its own powers. It might, with slight modifications,
be applied to all the kinds of plegmasias and active hemorrhages.

The second denomination, not so easily translated, expresses the sense of general
confusion and bruise, of patients labouring under bilious fever (meuingo-gastricu) com-
plain all over their limbs.

This sensation is b'kewise, it is true, experienced in pituitary fever; but this is more
particularly chcaracterized by languor and loss of strength. The same is to be observed
in many patients of a phlegmatic temperament.

The prostration, which is so remarkable a character of putrid fever, and in conse-
quence of which they are called adynamic, is easily recognized by tiie total cessation,
or by an impaired condition of all the functions performed by in u scalar organs, as volun-
tary motion, respiration, circulation, digestion, the excretion of urine, &c.

The disordered condition of the vital powers characterizes the ataxiae; there is con-
siderable irregularity in these fevers, with a very anomalous course of symptoms. In
this point of view, one might compare it to several kinds of nervous disorders.

Lastly, the word sideration appears to me to express, very forcibly, that sudden and
deep stupor which overwhelms patients seized with the plague of the East. — Author's
Note.

323

CLX VII. Of the fiower of the muscles; of the mode of estimating thatjiower.
The actual power of the muscles is immensely great, seems to grow in
proportion to the resistance which it meets with, and can never be esti-
mated with precision. Borelli was guilty of a serious mistake, in esti-
mating the force of a muscle by its weight, compared to that of another
muscle, for muscles may contain cellular tissue, fat, tendinous parts, and
aponeuroses, without being the more powerful. Their strength is al-
ways proportioned to the number of their fleshy fibres; hence, Nature has
multiplied those fibres in the muscles which are intended for powerful
action. And in order that this great number of muscular fibres might
not add too much to the bulk of the limbs, they are made shorter, by
bringing near to each other their insertions, which occupy extensive sur-
faces, whether aponeurotic or osseous. We may, in general, judge of the
power of a muscle, by the extent of the surfaces to which its fleshy fibres
are attached ; thus, the gamelli and the soleus have short compressed
fibres, and lie obliquely between two large aponeuroses.

If the force with which a muscle contracts, is proportioned to the
number of its fibres, the degree of decurtation of which it is capable, and
consequently, the range of motions which it can communicate to the
limbs, are proportioned to the length of the same fibres*. Thus, the sar-
torius, whose fibres are longer than any in the human body, is also capa-
ble of most contraction, and performs the most considerable motions of
the leg. It is impossible to fix any precise limits to the decurtation of
every particular muscular fibre ; for, if the greater part of the long mus-
cles of limbs lose little more than a third of their length, in contracting,
the circular fibres of the stomach, which, in its greatest dilatation, form
circles nearly a foot in diameter, may contract, to such a degree, when
this organ has been long empty, as to form rings of scarcely an inch in
circumference. In cases of extreme elongation or constriction, does the
change that take place, affect the molecules that form the muscular fibre,
or the substances which connect them together, or does it affect, at once,
both the fibre and the parts by which these fibres are united together?

However great the power of the muscles may be, a great part of this
power is lost, from the unfavourable disposition of ourorgans of motion;
the muscular powers, almost always parallel to the bones which they are
to move, act with the more disadvantage on these levers, as the main
line of their direction is further from the perpendicular, and is nearly
parallel to them.

The greater part of the muscles are, besides, inserted in the bones,
very near the articulations or the centre of motion, and move them as
levers of the third kind, that is, are always placed between the fulcrum
and the resistance; by multiplying thus, in the animal machine, the levers
of the third kind, Nature has lost in power, but has gained in strength,
for, in this kind of lever, the power moves through a very small space, but
makes the resistance most through a very considerable one. Besides, the
fleshy fibres, in shortening themselves, do not act directly on the tendon
in which the muscle terminates, these fibres generally join, in an ob-

* Besides these data, \ve should take into consideration the energy of the nervous
impulse, under which voluntary muscles contract. We perceive nearly as great differ-
ences, in the activity, the intensity, the frequency, and the continuance of muscular
contraction, result from the state of the nervous system, even in health, as may be im-
puted to the form and size of the muscles themselves, unless the difference of their con-
stitution or size, be very considerable. — Copland.

324

lique direction, the aponeurotic expansion formed by the tendinous cord,
as it penetrates into the muscular mass; now their action being exerted
in a direction more or less oblique, is decomposed and none is advanta-
geously employed, but that which takes place in the direction of the ten-
don. The muscles frequently pass over several articulations, in their
way to the bone which they are to move ; a part of their power is lost, in
the different degrees of motion on each other, of the parts on which
the bone rests into which the muscles are inserted. All these organic
imperfections are attended with an enormous misapplication of power
and with a waste of the greater part of it. It has been reckoned, that
the deltoid muscle employs a power equal to 2568 pounds to overcome a
insistence of 50. We are not to imagine, however, that there is a Ijss
of 2518 pounds ; for the deltoid muscle acting both on the shoulder and
on the arm, about one half of its power is employed on each of these
parts ; hence it is said, that in estimating the whole power of a muscle,
one should double the effect produced by its contraction, its action being
applied, at the same time, both on the weight which it raises, or on the
resistance which it overcomes, and on the fixed point to which its other
extremity is inserted.

If the muscles were quite parallel to the bones, they would be incapable
of moving them, in any direction. On this account Nature has, as much
as possible corrected the parallelism, by removing, as we shall see, in
speaking of the osseous system, the tendons from the middle line of di-
rection of the bones, and by augmenting the angles at which they are in-
serted into them, either by placing, along the course, bones which alter
their direction, as the patella and the sesamoid bones; by increasing the
size of the articular extremities of the bones, or by pullies, over which
the tendons or the muscles themselves are reflected, more or less com-
pletely, as is the case with the circumflexus palati and the obturator in-
ternus.

Nature has not, therefore, neglected mechanical advantages as much
as one might be led to imagine, on a slight examination of the organs of
motion. And if it be considered, that in the different conditions of life,
we do not require strength so much as rapidity of motion, that the power
might be gained by increasing the number of fibres, while it was impos-
sible to obtain velocity, by any other means than by employing a parti-
cular kind of lever, and that, in short, to give our limbs the most advan-
tageous form, it was necessary that the muscles should be applied to the
bones, it will be confessed, that in the arrangement of these organs, Na-
ture, in frequently sacrificing power to quickness of motion, has conci-
liated, as much as possible, these two almost irreconcileable elements.

Though the lever of the third kind is that most frequently employed in
the animal economy, the two other kinds of lever are not altogether ex-
cluded from it ; there are even limbs which represent different levers, ac-
cording to the muscles which set them in motion ; thus, if we take the
foot as an instance, it will present us with levers of every kind. The
foot, when raised from the ground and held up and raised towards the
leg, form,s a lever of the first kind; the fulcrum is in the articulation and
separates the power, which is at the heel, from the resistance which is
at the tip of the foot that points downwards ; if this end of the foot rest
on the ground, and if we stand on tip-toe, they are changed into levers of
the second kind ; the power continues at the heel, but the fulcrum is re-
moved to the other extremity of the lever, and the resistance to the mid-
dle; and this resistance is very considerable, since the whole weight of

325

the body rests on the articulation of the foot with the leg. In standing
on tip-toe, the muscles of the calf of the leg become prodigiously fatigued,
though their action is assisted by the most favourable lever*, adapted to
the greatest resistance which Nature can oppose to herself. Lastly, the
foot moves as a lever of the third kind, when we bend it on the leg.

CXLVIII. What is called the fixed point, in the action of muscular
organs, does not always deserve that name. Thus, though it may bo said,
very correctly, that the greatest part of the muscles of the thigh have
their fixed points in the bones of the pelvis, to which their upper extre-
mity is attached, and though they move the femur on th.1 ilia which are
less moveable ; when the thigh is fixed by the action of other muscles,
these move the pelvis on the thigh, and that which was the fix?d point,
becomes moveable. The same applies to the other muscles of the body,
so that the fixed point is merely that which, generally, is a fulcrum to
the muscular action. This necessary fixed state of one of the bones, to
which is attached one of the extremities of a muscle which we wish to
contract, renders it necessary, in performing the slightest motion, thai
several muscles should be called into action, which implies a very com-
plicated mechanism. Nothing is easier to prove. Suppose a man stretched
on the ground or lying on his back; if he wish to raise his head, it will
be necessary that this chest become the fixed point of action of thesterno
cleido mastoidei, whose office it is to perform this motion. Now, in order
that the pieces forming this osseous structure may remain motionless, it
will be required, that the chest should be fixed by the action of the abdo-
minal muscles which, on the other hand, have their fixed point in the
pelvis that is itself fixed in its place, by the contraction of the glutaei
muscles. It was on this principle that Winslovv first suggested, that in
reducing a hernia, the patient should be laid in an horizontal posture^,
•with injunctions not to raise his head, that the abdominal muscles being
relaxed, their different openings might yield more easily to the reduction
of the parts.

In case the two opposite points to which the extremities of a muscle
are attached, are equally moveable, they approach towards each other,
during the contraction of the muscle, by making them move through
equal spaces. These spaces would not be equal, if the mobility were
different. Each muscle has its antagonist, that is, another muscle whose
action is directly opposed to it. Thus, the flexors balance the action of
the extensors, the adductors perform motions different from those of the
abductors. When two antagonizing muscles of equal power act, at the
same time, on a part equally moveable, in every direction on the oppo-
site powers, neutralize each other, and the part remains motionless. If
there is a difference in the degree of contraction, the part is directed to-
wards the muscle whose contraction is the most powerful : if the opposi-
tion is not direct, the part follows a middle direction, between the two
powers which move it. Thus, the rectus externus muscle of the eye is
not antagonized by the rectus inferior ; hence when these two muscles
come to contract, at the same time, the eye is not carried downward or
outward, but at once downward and outward ; it is then said to mote in

* Of levers with arms of unequal length, that of the second kind is the most favoura^
ble, since the arm of the power is uniformly longer than that of the resistance. Cop-
land.

the diagonal of a parallelogram of which the sides are represented by the
muscles in action.

CLXIX. Of the nature of muscular flesh. I shall not speak, at present,
of the manner in which the muscles receive nourishment, by retaining
within the meshes of their tissue, the fibrina which the blood conveys to
them in such quantity, that several among the ancients and moderns have
called the blood, " liquid flesh ;" an expression at once forcible and cor-
rect, since all the organs are repaired and grow, by the solidification of its
different parts. Haller first observed that most of the muscular arteries
were very tortuous in their course to the muscles. This disposition,
which cannot fail to slacken, very considerably, the course of the blood,
favours the^ formation and the secretion of the fibrous element which the
muscles appropriate to their own substance, and to which it bears so
strong an affinity. Motion influences, in a very remarkable manner, this
nutritive secretion. The muscles that are most in action, uniformly
acquire the greatest size and strength ; if left in a state of complete inac-
tion, they become exceedingly reduced in size, from the suspended secre-
tion of the fibrinous principle. Muscular motion promotes, very remark-
ably, the circulation and the distribution of all the fluids. The flow of
venous blood, after bleeding, is never copious, unless the muscles of the
fore arm are made to contract, by making the patient hold the lancet case,
and desiring him to move it round his hand. ,

The chemical nature of the muscular fibre is nearly the same as that of
the fibrina obtained from the blood*. Like the latter, it contains a great
quantity of azote, and is, consequently, very much animalized and ex-
ceedingly putrescent. It is from muscular flesh, that M. Berthollet ob-
tained, in considerable quantity, the peculiar animal acid, called by that
chemist, the zoonic acid^. Lastly, the element of the blood, by means of
which the muscular flesh is repaired, fibrina, is already imbued with vital
properties, even while it yet flows in a state of combination with the other
parts of the fluid. This fibrina, extracted from the blood and subjected
to the galvanic influence, is distinctly seen to quiver and contract under
that influence. At what period does this substance acquire the power of
contracting-? It is, doubtless, at the moment when it becomes organized,
in passing from the fluid to the solid state. What relation does there
exist, between the organization of matter and the vital properties with
which it is endowed? This question cannot be answered, in the present
state of our physiological knowledge:}:.

CLXX. Galvanism. A Professor of Anatomy in the University of
Bologna, Galvani, was one day making experiments on electricity. In
the laboratory, not far from the machine, lay some skinned frogs, of which

* Nothing1 can prove, in a more complete manner, the essential difference between
the fleshy parts of muscles and their tendinous and aponeurotic parts, than the chemical
analysis of these organs. The tendons and aponeuroses may be completely resolved
into g-elatine, by long boiling1, which, on the contrary, parches the muscular flesh, by
exposing1 the fibrina, in consequence of the melting of the fat of the cellular tissue, and
of the albuminous juices in which it is enveloped. — See the Chapter at the end of the
APPKSBIX, on the Chemical Constitution of the Animal Textures and Secretions.

j" Another secretion which is obtained abundantly from muscular tissues, and denomi-
nated osmazome by modern chemists, may be noticed. It appears to be a species of
animal extract, of a brown colour, aromatic, and very nutritious. It gives soup its savour,
and forms a great proportion of the gravy of meat. Although osmazome is an animal
product, it is found on analysis in some species of mushrooms.

T See APPENDIX, Note F F.

327

the limbs were convulsed every time a spark was taked. Galvani, struck
with the phenomenon, made it a subject of inquiry, and found that metals?
applied to the nerves and to the muscles of these animals, determined
quick and strong contractions, when they were disposed in a certain man-
ner. He gave the name of Animal Electricity to this set of new pheno-
mena, from the analogy he thought he perceived between its effects and
those of electricity. The discovery was made public: many scientific
men, chiefly those of Italy, and Volta among others, were eager to make
additions to the labour of the inventor. The Medical Society of Edin-
burgh thought it right to take this point of physiology as the subject of
one of its annual prizes, which was adjudged to the work of Professor
Creve of Mentz, in which the term metallic irritation (irrllamentum me-
lallorum} is substituted for that of animal electricity. This new expres-
sion is essentially bad, since it implies that irritation by metals can alone
determine the galvanic phenomena, when charcoal, water, and many other
substances, produce them as well. The term of animal electricity has
been also laid aside, notwithstanding the great analogy between the effects
of electricity and those of galvanism, and this last name has been pre-
ferred, which, applying equally to the whole of the phenomena, immor-
talizes the name of the first observer*.

To produce the galvanic phenomena, it is necessary to establish a
communication between two points of a series of nervous and muscular
organs. In this way there is formed a circle, of which one arc is com-
posed of the animal parts that are subjected to the experiment; while the
other arc is represented by the instruments of excitation, which consist
commonly of several pieces, some of them placed under the animal parts,
and called supports, and the others, by which the communication with
these is established, called communicators.

To form a complete galvanic circle, take the thigh of a frog stripped of
its skin, detach the crural nerve down the knee, and apply it on a plate
of zinc; let the muscles of the leg lie on a plate of silver, then complete
the arc of excitation and the galvanic circle, by establishing a communi-
cation between the two supports with an iron wire, or copper, tin, or
lead: at the moment of touching the two supports with the conductor,
a part of the animal arc formed by the muscles of the leg, will be con-
vulsed. Although this arrangement of the animal parts, and of the gal-
vanic instruments, is the one most favourable to the production of these
phenomena, there is room for varying a good deal the composition of the
animal arc and the arc of excitation. Thus, you obtain contractions, by
placing the two supports under the nerve, and leaving the muscles with-

* SUI.ZF.H, in the Memoirs of the Academy of Berlin, and in his " General Theory of
Pleasure" a work published in 1757, and inserted in 1769, in a collection published by
Bouillon, under the title of the " Temple du Honheur," tome III. p. 124, had mentioned,
that two plates of different metals being placed one above and another below the
tongue, and inclined towards each other at their extremities, at the moment when they
touched each other, he felt a sharp taste, which was frequently accompanied by a pecu-
liar faint light. COTUGNO had related in a Journal published at Bologna, in 1786, that
a student of medicine, while dissecting a living- mouse, was surprised to observe an elec-
tric movement of its limbs whenever the scalpel touched one of its nerves. It was not
until 1789, that GALVANI commenced his experiments. But he cannot be the less con-
sidered as the discoverer of this class of phenomena, even supposing that he knew the
experiments we have noticed, for their authors drew no conclusion from them ; while,
on the contrary, Galvani repeated, varied, and multiplied them, and was the first to.
contend for a species of electricity in the animal economy.

328

out the galvanic circle; which proves, that the nerves essentially consti-
tute the animal arc. To conclude, the galvanic circle may be entirely
animal: for this purpose, take a very lively frog, that is to say, .me en-
joying strong contractility: after insulating the lumbar nerves, present
these nerves to the thigh of the frog ; at the moment of contact, the limb
will be convulsed. Professor Aldini is the first author of this experiment,
which is really one of the most curious, as it leads more directly to the
explanation of the influence of nerves on muscular organs.

There is no need that the nerves be untouched to allow the contrac-
tions, they are observed when these organs are tied or cut, provided there
be simple contiguity between the two ends made by the section. This
shows that no rigorous conclusions must be drawn from what happens in
galvanic phenomena, to what takes place in muscular action; since it is
enough that a nerve in man be cut or compressed by a ligature, to take
from the muscles to which if. is sent, the faculty of moving. I have,
however, observed, that disorganizing, by strong contusion, the nerve
which forms the whole or merely a part of the animal arc, interrupts, or
at least greatly impedes, the galvanic current.

The epidermis obstructs galvanic action; which always is faint in parts
so covered. When it is moist, thin, and delicate, the interruption is not
complete; and hence the possibility is inferred of making on one's self the
following experiments.

Lay upon the tongue a plate of silver, and a plate of zinc beneath; let
their edges touch, and you will feel a sharp t?,ste with a slight quivering.
Apply upon the eyes two pieces of different metals; make them commu-
nicate, and you will perceive sparks. Put apiece of silver in your mouth,
and a piece of tin into your anus, or copper, or any other metal; connect
them with an iron wire: the long hollow muscle, which, reaching from
the mouth to the anus, forms the base of the digestive canal, feels a con-
siderable shock: this has been carried to the length of exciting a gentle
purging, accompanied with slight cholic. Humboldt, after detaching the
epidermis from the nape of the neck, and the back, by two blisters, had
metals applied to the parts laid bare; and felt in each sharp prickings,
accompanied with a sero-sanguineous excretion, at the moment of com-
munication.

You may construct the arc of excitation with three kinds of metal, or
two, or even one; with alloys, amalgams, or other metallic and mineral
combinations; with carbonaceous substances,* Sec. and it is observed, that
metals, which are in general the most powerful exciters, provoke con-
tractions with the greater success the larger surface they present. The
metals have more or less power of excitation: thus it is found that zinc,
gold, silver, and tin, hold the first rank; then copper, lead, nickel, anti-
mony, &c. without any apparent relation between their different degrees
of exciting power, and their physical properties, as their weight, malle-
ability, Sec.

CLXXI. Galvanic susceptibility is like muscular irritability; it is ex-
hausted by too long exertion; and returns when the parts are left for a
time to repose. Dipping the nerves or muscles in alcohol or opiate
solutions, weakens and even will extinguish this susceptibility, in the
same manner, no doubt, as in the living man, the immoderate use of the

* 1 employed successfully, in the winter of the year 1800, pieces of ice, both as sup-
ports and as communicators.

same substances benumbs and paralyzes the muscular action. Immer-
sion in oxygenated muriatic acid restores to the exhausted parts the
power of being affected by the stimulus. Humboldt has observed, that
the season of spring, as well as the youth of the frog, was favourable to
the production of the phenomena: and that the fore feet of these creatures
with which the male fixes himself on the back of the female, by pressing
her sides, are more excitable than the hind feet; whilst in the other sex,
it is the hind feet that are the most susceptible. Halle ascertained, by
experiments made at the School of Medicine in Paris, that the muscles
of animals killed by repeated shocks of an electrical battery, receive an
increase of galvanic susceptibility; that this property subsists, without
alteration, in animals dead of asphyxia, or killed by immersion in mer-
cury, pure hydroden gas, carbonated hydrogen, oxygenated muriatic
acid, and sulphureous acid gases, by strangulation, by privation of air in
an exhausted receiver; that it is weakened after suffocation by drowning,
by sulphurated hydrogen, azote, and ammoniacal gas, and absolutely de~
stroyed by suffocation in the vapour of charcoal. Spring is the season
in which galvanic experiments succeed best; an excess of life seems, at
that time, to animate all beings: it is accordingly at this epoch, that the
greater part of them are employed in the reproduction of their kind.

CLXXII. Galvanic susceptibility disappears in the muscles of warm'
blooded animals, as the vital warmth goes off. Sometimes even, when
their life has ended in convulsions, their contractility is gone, though
there be still warmth, as if this vital property were exhausted by the con-
vulsions of death. In the cold-blooded, susceptibility is more permanent:
long after separation from the body, and even to the moment when pu-
trefaction begins, the thighs of frogs are affected by galvanic excitation;
no doubt, because, in these animals, irritability is less intimately con-
nected with respiration, because life is less one, is more divided among
different organs which have less need of action on each' other to produce,
its phenomena.

Contractility is then, as I have shown in another work, too fleeting in
the human body*, to enable us to derive from galvanic experiments on
it after death, any light on the greater or less weakening of this vital
property in different diseases. Those authors who have maintained that
galvanic susceptibility is sooner extinct on the bodies of those that die of
scorbutic affections, than of those that die of inflammatory diseases, have
suggested a probable conjecture, which cannot, however, be established'
on experiment.

Dr. Pfaff, Professor in the University of Kiel, who, next to Humboldt,
of all the scientific men of Germany, has attended most successfully to
experiments on galvanism, has had the goodness to communicate to me
the following facts.

The galvanic chain produces sensible actions, that is to say, contrao
tions, only at the moment in which it is completed, by establishing a
communication among its parts. After it is made, that is, during the
time that the communication remains, all appears tranquil; yet the gal-
vanic action is not suspended. In fact, excitability appears singularly-
increased or diminished in the muscles that have been left long in the
galvanic chain, according to the variations of the reciprocal situation of

the new"born or Ver7 y°un£ info"** almost immediately

330

the associated metals. If the silver have been applied to the nerves,
and the zinc to the muscles, the irritability of these is increased, in pro-
portion to the time they have remained in the chain. By this means,
you may revivify, in some sort, frogs' thighs, which will after wards obey
an influence that was no longer sufficient to excite them. By allotting
the metals differently, applying the zinc to the nerves, and the silver to
the muscles, the opposite effect takes place, the muscles which were in-
troduced into the chain with the liveliest irritability, seem entirely para-
lyzed, if they have remained long in that situation.

This difference depends, very evidently, on the direction of the galvanic
fluid, determined towards the nerves or towards the muscles, according
to the arrangement of the metals. It is of importance to be known for
the application of galvanism to the treatment of disease. Where the ob-
ject is to revive enfeebled irritability, it is better to employ the tranquil
and permanent influence of the closed galvanic chain, by distributing the
silver and zinc, so that the silver shall be nearest to the origin ot% the
nerves, and the zinc upon the muscles of which it is wished to re-excite
the torpid or suspended action, than to employ that sudden influence,
\vhich in an instant, excites and is gone. Professor Pfafi° told me, he had
treated successfully a hemiplegia, by placing silver within the mouth,
and a plate of zinc on the paralyzed arm; at the end of twenty-four hours
of uninterrupted communication, the limb could already exert some slight
motions. To diminish, on the other hand, the irritable energy in many
spasmodic affections, you must invert the application of the metals, place
the zinc as near as possible to the central extremity of the nerves, and
the silver on their superficial terminations.

CLXXIII. Apparatus of Volta, or galvanic pile. Curious to ascertain
the relation apprehended by several natural philosophers, between elec-
tricity and galvanism, Volta invented the following apparatus, which is
described, as well as the effects it produces, in a memoir presented by
him to the Royal Society of London. These' effects show the most
striking analogy between these two orders of phenomena, as will be seen
by a succinct view of them. Raise a pile, by laying successively, one
above another, a plate of zinc, a piece of moistened paste-board, a plate
of silver; then a second plate of zinc, Sec. till the pile is several feet high;
for the effects are stronger the higher it is: then touch at once the two
extremities of the pile with the same iron wire: at the instant of contact,
a spark is seen at the extremities of the pile, and often, at the same time,
luminous points, at different heights, in places where the zinc and silver
touch. Tried by the electrometer of Coulomb, the extremity of the pile,
which answers to the zinc, appears positively electrified; that which is
formed by the silver, gives, on the contrary, indications of negative elec-
tricity.

If, after wetting both hands, by clipping them in water, or still better
in a saline solution, you touch the two extremities of the pile, you feel in
the joints of your fingers and elbow, a shock followed by an unpleasant
pricking.

This effect may be felt by several persons holding hands, as in the Ley-
den experiment; it is the more sensible, the composition of the chain be-
ing in other respects the same, as the chain consists of fewer people, and
a£ they are better insulated.

Notwithstanding this great resemblance of the effects of galvanism to
those of electricity, it differs from it essentially in this, that the voltaic

331

pile is constantly electrifying itself spontaneously, that its effects seem in-
creased, the more they are excited, and are speedily renewed in greater
strength, whilst the Leyden phial, once discharged, requires to be elec-
trified anew. This loses, moreover, by damp, its electrical properties,
whilst those of the pile remain the same, though water is running on all
side, and are quenched only by an entire immersion in that fluid.

If you introduce into a tube filled with water, and hermetically closed
•with two corks, the extremities of two wires of the same metal, which,
at the other extremity, are in contact, one in the summit and one with
the base of the galvanic pile, these two ends, when brought within the
distance of a few lines, undergo manifest changes, at the moment of touch-
ing the extremities of the pile. The wire in contact with the extremity
which answers to the zinc, becomes covered with bubbles of hydrogen
gas; that which touches the extremity formed by the silver, becomes
oxydized. If the ends of the wire dipping into the water, are brought into
contact, all effect ceases: there is no disengaging of bubbles on one side,
no oxydizement on the other. The plates of zinc and silver become alike
oxydized in the pile, but only on the surfaces which touch the moisten-
ed pasteboard, and very little, or not at all, on the opposite surfaces, &c.

Facts so singular could not but awaken the attention of all natural
philosophers. Accordingly, there was a great eagerness, every where,
to repeat and verify these first experiments, to vary and to extend them,
and to rectify the errors into which their authors might have fallen.
Lastly, it has been attempted to explain the manner in which the apparatus
acts in the production of hydrogen gas and in oxydizement.

M. Fourcroy ascribes this phenomenon to the decomposition of water
by the galvanic fluid, which abandons the oxygen to the wire that touches
the positive extremity of the apparatus, then conducts the other gas, in
an invisible manner, to the extremity of the other wire, where it allows
it to escape ; and this opinion, supported by many experiments, detailed
in a Memoir presented to the National Institute, is the most probable of
^11 that have hitherto been suggested*.

The galvanic pile has been employed, with effect, to produce witli
more energy, muscular contraction. If you place in the mouth of an ani-
mal, fresh killed, a conductor attached to one of the poles or extremities
of the pile, and insert into the rectum, the conductor connected with the
other extremity, you observe contractions so strong, that the whole body
of the animal quivers and is agitated, the eyes roll in their socket*, the
jaws strike against each other, and the tongue is thrust out. The same
effects take place after decapitation of the animal. These experiments
have been repeated on the bodies of persons executed by the guillotine :
by applying to the neck, the head that had been separated from it, and
applying to both conductors connected with the pile, effects have been
produced, which seemed at first miraculous. There are fewrauscies that re-
tain, longer than the diphragm, their sensibility to the galvanic action;
in the heart, and in the intestines, it is the same. I know not why the
internal muscles have been held by many authors to be insensible to this
kind of excitation. I have seen them constantly obey it, and many ex-

* It is unnecessary to refer to the brilliant discoveries which have been made* in chemi-
cal science by means of galvanism.

332

periments made publicly in my lectures, have ahvay afforded me this re-
sult*.

CLXXIV. In the first edition of this work, the article galvanism prid-
ed here* Since its publication, there has been an accession of new facts
to those already known. Volta came to'Paris: he gave an exposition of
his doctrine, in several Memoirs read before the National Institute of
France, and he repeated before acommitee, the principal experiments on
which it is founded* They have appeared so conclusive, that the theory
of this illustrious philosopher has been unanimously adopted, and at this
day, all men of science admit the entire identity of the phenomenon of
galvanism, and those of electricity. Certain bodies, therefore, in nature,
and especially metals possess the property of electrifying themselves,
that is to say, of producing the greater part of the phenomena which
denote the accumulation of electricity in a body, such as shocks, sparks,
irritations, Sec. merely by contactf.

It maybe thought that galvanism* being only a new form of electrical
action, ought to be confined to books of natural philosophy; and in fact,
in the present state of things, it belongs rather to the physico-chemical
sciences, than to those of the animal economy. However the galvano-
electric irritation produces on our organs, effect more decided than the
ordinary effect of electricity. It seems to have more intimate relations
•with them: accordingly, it has been endeavoured to bring it into use in
the treatment of disease, The experiments made by M. M. Halle and
Thillaye, prove that the effects of the pile penetrate, and effect the nerv-
ous and muscular organs, more deeply than the common electrical appa-
ratus; that they provoke lively contractions strong sensations of pricking
and burning, in parts which disease renders insensible to electrical sparks,
or even shocks. A man whose muscles of the left side of his face were
all paralyzed, found no effect from the electric shock. He was exposed
to the action of a pile of 50 plates, by communications, through chains
and metalic exciters, of the two extremities of the pile, with different
points of the cheek affected, At the moment of contact, all the muscles
of the face became convulsed with heat* pain, Sec. These endeavours
repeated, during more than six months, have, by degrees, brought back
the parts to their natural state.

Dr. Alibert has applied galvanism with still more decided success, to
a priest attacked with hemiplegia. This patient, who lay in the wards of
the Hospital of St. Lewis, has recovered the use of the palsied side, suf-
ficiently to walk, almost without assistance, and to use his right arm ,as
he wants it. The treatment has gone on for several months: the pile
employed consisted of fifty plates of zinc and copper, I am trying the
same apparatus upon a Swedish officer, for incomplete deafness, which
has hitherto resisted all known applications, administered in different
parts of Germany, Strong electrical shocks, recommended by Hufeland,
had dispelled in great measure, the hardness of hearing; but this amend-
ment was only temporary: it ceased with the application of the remedy.
The first trial of galvanism was attended with the same effect. The ex-

* See the Note in the APPENDIX ort the subject of galvanism, for some observations
as to the effects of this agent on some of the animal textures.

j See APPENDIX, Note G G for an account of some receftt views respecting the rela-
tions and agencies of galvanism, &c.

333

tremity of a conductor being placed in the exterior auditory duct of the
right side (moistened with a solution of muriate of ammonia, as well as
the pieces of cloth which made part of the pile) the left hand, dipped in
the same liquid, touched a conductor placed at the copper pole: imme-
diately an irritation, followed by painful prickings, was felt in the ear,
the outer part of which became very red. The brain partook in the ex-
citement, the eyes flashed, and the effect was such, that after remaining
a few minutes in the closed galvanic circle, the patient was taken with a
sort of inebriation. I propose to direct, as has been done at Berlin, a
more immediate irritation of the right ear, which is the deafest, by intro-
ducing behind the velum palati, on the guttural orifice of the eustachian
tube, the button which is at the end of the conductor of the zinc pole; or
else to make this extremity correspond with a denuded surface, by a blis-
ter behind the diseased ear.

To use galvanism in paralysis of the bladder, it would be necessary to
place the conductor of the zinc pole in the rectum, that of the other pole
answering to a blister applied above the pubis, or else to the upper part
of the thigh. In women, the vagina would be preferable to the rectum ;
the soft parts which perform the part of moist conductors fulfilling that
office the better, the thinner they are. Galvanism is therefore an ener-
getic stimulant of the vital powers; it may be employed, with great ad-
vantage, in all palsy, both of sensation and of motion. It acts as a sti-
mulant, reddening the skin where it is applied, by determining thither
the flow of blood, with heat. Monro could make his nose bleed at plea-
sure, by applying it to the pituitary membrane. I have made various
experiments, having in view to establish the efficacy of galvanism, in
white swelling of the joints, and in ulcers which require excitement; such
as those which are attended with a scorbutic affection, Sec. in all these
cases, it acts as a resolvent, and as a ionic. I shall communicate, in my
Surgical Nosography, the results of these attempts. Cases of Asphyxia
are those in which the greatest good may be hoped from galvanism,
provided the application be made before all the vital heat be extinct*.

Those who wish fuller details on galvanism, and on its possible appli-
cation to the treatment of disease, will do well to consult the Complete
History of Galvanism, by Professor Sue, the eulogium of Galvani, by Dr.
Alibert, in the beginning of the fourth volume of the Memoirs of the
Medical Society of Emulation, and the work of Dr. Aldini, nephew to
the celebrated author of the discoveryf.

CLXXV. General view of the osseous system. Man, as well as the other
red-blooded animals, (the mammiferae, birds, reptiles, and fishes,) has an
internal skeleton, formed of a great number of bones articulated together,
and set in motion by the muscles with which they are covered. The
white-blooded animals have no internal skeleton, and are enveloped, in
hard, scaly, or stony parts, forming what is called their outer skeleton.

* Dr. PHILIP is of opinion that, in those diseases in which the original cause of de-
rangement is in the nervous ramifications, or spinal cord, only, where the sensorial
functions are entire, and the vessels healthy, and the po\vcr of secretion is alone in
fault, galvanism will oiten prove a valuable means of relief. He has frequently em-
ployed it in hab'tual asthma, « and almost uniformly with relief." He aho recommends
this active agent in a torpid state of the biliary functions, and In indigestion. See a
Treatise on Indigestion, by Dr. Philip, 3d edition,— Copland.

t Se« APPENDIX, Note G G.

334

Some animals are entirely destitute of hard parts: this is the case with the
zoophytes, some worms and insects. The internal structure of bones is
composed of nearly the same materials in all animals: viz. gelatine and
salts containing- a calcareous basis. The external skeleton of white-blood-
ed animals bears a much greater resemblance to the epidermis than to
the osseous system of the red-blooded animals. Like the epidermis, it
undergoes changes of decomposition and renovation. Thus, the lobster
parts with its shell, every year, when the body of this crustaceous animal
increases in size, and it is replaced by a new envelope, which is, at first,
very soft, and which gradually acquires the same consistence as the
former. Lastly, the skeleton of birds differs from that of all other ani-
mals, in having its principal bones pierced by openings communic'iting
with i he lungs, and always filled with an air rarified by the vital heat,
winch greatly assists in giving to them that specific lightness so essential
to their peculiar mode of existence.

The osseous system serves as a foundation to the animal machine,
yields a firm support to all its parts, determines the size of the body, its
proportion, its form and attitude. Without the bones, the body would
have no permanent form, and could not easily move from one place to
another. When, from the loss of the calcareous earth to which they owe
their hardness, these organs become soft, the limbs deformed, standing,
and the different motions of progression, become after a time impossible.
Such are the effects of rachitis, a disease of which the nature is well
understood, though we are not the better informed with regard to the
manner in which its causes operate, or the medicines which it requires.

The vertebral column forms the truly essential aud fundamental part
of the skeleton; it may be considered as the base of the osseous edifice,
as the point in which all their efforts terminate, as the centre on which
all the bones rest in their various motions; since every effort or shock, in
any way considerable, is felt there. Moreover, it contains in the canal
with which it is perforated, the cerebral prolongation, which furnishes
most of the nerves in the body.

In order that it may support all the different parts and at the same time,
protect the delicate organ which it contains*, and adapt itself to the va-
rious attitudes required by the wants of life, it was necessary that the
vertebral column should possess, besides great solidity, a sufficient degree
of mobility; it possesses both these advantages, and owes the former to
the breadth of the surfaces by which its bones are articulated together,
to the size, the length, the direction, and the strength of their processes,
and to the great number of muscles and ligaments connected with it: it
owes its freedom of motion to the great number of bones of which it is
formed. Each single vertebra has but a slight degree of motion, but as
they all have the power of moving at once, the sum of their individual
motion added together, gives as the result a general motion which is

'* The peculiar manner in which the vertebree grow, is itself accommodated to the
delicacy of the spinal marrow; consisting-, for a considerable length of time, of several
pieces divided by cartilages, the circumference of the opening in these bones, becomes
enlarged, with the enlargement of the spinal marrow, as we grow older. The circum-
ference of the foramen of the occipital bone and that of the first vertebra which cor-
respond to the thickest part of the spinal marrow, is, on thai, account, formed of four
distinct pieces separated by cartilages in the first of' these bones, and of five pieces in the
other.— ^Author'* J\"otp.

335

considerable, and which is estimated by multiplying the single motion
by the number of vertebrae.

The centre of the motions, by which the spine is extended or bends for-
ward or backward, is not situated in the articulation of the oblique pro-
cesses, as it is maintained by Winslow, in the Memoirs of the Academy
of Sciences for the yeur 1730, nor in the invertebral substance. The exten-
sion and flexion of the vertebrae are not performed in two centres of mo-
tion, the one in the intervertebral substance, the other in the articulation
of the articulating processes, as was imagined by Cheselden and Barthez,
but on an axis crossing the bone between its body and its great aperture.
The anterior part of the bone and its spinous process perform, around
this imaginary axis, motions forming part of a circle, and whirh though
limited, are not the less marked ; and in these motions, the articulating
surfaces separated by the intervertebral substance are brought into close
contact, and this substance is compressed, while the oblique processes
move on one another, and tend to part from one another: this is what
happens in bending the trunk, while, in straightening it, the anterior sur-
faces are removed from each other, the posterior surfaces approach, come
closer and closer together, and finally touch throughout the whole of
their extent, when the extension of the trunk is carried as far as the spi-
nous processes will allow.

The use of the ridge of projections which arise from the posterior part
of the vertebrae, is to limit the bending of the trunk backwards, and to
enable the muscles which straighten it, to act with a more powerful lever.
When, from the habit of an habitually erect posture, these processes have
been prevented from growing in their natural direction, the trunk may be
bent backward to such a degree, that the body forms, in that direction,
an arc of a circle. It is thus, that they train, from the earliest infancy,
the tumblers who astonish us by the prodigious suppleness of their loins,
in bending backward so as to change the natural direction of their spinal
processes.

It was of consequence, that the motions of the vertebral column should
take place, at once, in a great number of articulations, as the curvatures
are thus less sharp, and thus the organization of the spinal marrow,
•which is very delicate, is not injured. Thefibro-cartalaginous substances
which connect together the bodies of the vertebrae, between which they
lie, possess a remarkable degree of elasticity, like all bodies of the same
kind, and support, in a favourable manner, the weight of the body. When
the pressure which they experience is long continued, they somewhat
yield, and diminish in thickness, and this effect taking place, at the same
time, in all the intervertebral substance, our stature is sensibly lowered. The
body is, on that account always shorter in the evening than in the morn-
ing, and this difference maybe considerable, as is mentioned by Buffon to
have been the case in several instances. The son of one of his most
zealous coadjutors (M. Gueneua de Montbeillard, to whom is due the
greatest part of the natural history of birds,) a young man of tali stature,
five foot nine inches when he had reached his complete growth, once lost
an inch and a half, after spending a whole night at a ball. This differ-
ence in the stature depends, likewise, on the condensation of the cellular
adipose tissue at the heel, which forms, along the whole of the sole of
the foot, a pretty thick layer.

The thigh bone is longer in man than in quadrupeds, and this relative

336

length of the thigh, gives him exclusively the power of resting his body
by sitting.

The tibia is the only one of the bones of the leg which affords a support
to the body. The fibula, situafed at its outer part, too thin and slender to
support the weight of the body, is of use merely with regard to the arti-
culation of the foot, on the outside of which it lies. It supports the foot,
and prevents its starting outward by too powerful an abduction. The
foot, in this motion, is forced against the fibula which is bent outwardly,
the more so when the person is advanced in years, and has, therefore,
called into frequent action this force of resistance. Animals that climb,
as the squirrels whose feet are in a continual state of abduction, have a
rvery large and strongly curved fibula*.

The number of the parts which form the feet, besides giving to these
parts a greater solidity, is further useful in preventing the foot from
being too violently shaken by striking the ground, in our various motions
of progression. In leaping from a height, we endeavour to fall on our
toes, that the force of the fall may be broken, by being communicated to
the numerous articulations of the tarsus and the metatarsus, and may not
affect the trunk and head with a painful and even dangerous concussion.
It is well known, that when, in falls, the whole soal of the foot strikes
against the ground, fracture of the neck, of the thigh bones, and concus-
sion of the brain and other organs, is not an unlikely consequence.

CLXXVI. Structure of the bones. Whatever difference there may at
first sight, seem to exist, between a bone and another organ, their compo-
sition is the same. Its structure consists of parts that are perfectly si-
milar, with the exception of the saline inorganic matter which is deposi-
ted in the cells of its tissue, which gives it hardness and that solidity
which constitutes the most striking difference that distinguishes it from
the soft parts. This earthy substance may be separated, by immersing the
bone in nitrie acid diluted in a sufficient quantity of water. It is then
found, that it is a phosphate of lime which is decomposed, by yielding
to the nitric acid its calcareous base. The bone, thus deprived of the
principle to which it owes its consistence, becomes soft, flexible, and re-
sembles a cartilage, which is resolvable, by long maceration, into a cel-
lular tissue similar to that of the other parts. This tissue contains a
considerable number of arteries, veins, and lymphatics. The bones
are, therefore, mere cellular parenchymas whose areolse contain a crys-
tallized saline substance, which they separate from the blood, and with
which they become incrusted, by a power inherent in their tissue, and
peculiar to it. The same result may be obtained by inverting the analy-
sis. If a bone be exposed to boiling heat, for a few hours, in Papin's di-
gester, all its organized parts become dissolved, melt and furnish a quan-
tity of gelatine, after which there remains only an inorganic saline con-

• This curvature is well marked in the chief -d'ceuvre of antique sculpture, and gives
to the lower part of the leg, in our most beautiful statues, a thickness which does not
at all agree with our present notions of elegance of form. This seems to me to prove,
that the beautiful is not invariable, as has been asserted by many philosophers ; and
that ideal perfection is not precisely the same in all ages, in nations equally civilized.
The truth of this observation may' be proved by the Apollo Belvidere ; his knees are
rather large and close tog-ether, and this form is the most beautiful representation of
Nature, which gives to the femur an obliquity inwards, the knees not being perfectly
straight, and without any disproportion between the calf and the thin part of the leg. —
Author's Note.

337

cretion ; which may, likewise, be obtained in a separate state, calcining
the osseous part. The different proportions of the saline to the organized
part, vary considerably at different periods of life : the bones of the em-
bryo are, at first, quite gelatinous. At the period of birth, and during the
first years of life, the organic part of the bone is in greater proportion ;
the bones are less apt to break, more flexible, possessed of more vitality,
and, when fractured, are more speedily and more easily consolidated, In
youth, the two constituent parts are nearly in equal quantities; in adults,
the calcareous earth* alone forms two thirds of the osseous substance.
At last, gradually increasing in quantity, it displaces, in old people, the
part that is organized : hence their bones are weaker, more liable to frac-
ture, and unite less readily. One may therefore say, that the quantity of
phosphate of lime deposited in the bones, is in the direct ratio of the age;
and that, on the contrary, the energy of the vital faculties of these or-
gans, their flexibility, their electricity, their aptitude to become conso-
lidated, when their continuity is destroyed by accidents, are in an inverse
ratio.

Anatomists distinguish in bones three substances, which they term
compact, spongy, and reticular. The first, which is the hardest, collect-
ed in the centre of the long bones, where the greatest stress of the efforts
applied to their extremities rests, gives to the bone the strength which it
required. Its formation has been explained, in various ways; some have
maintained that it owed its hardness to the pressure applied to its middle
part by the tv/o extremities of the bone ; in the same manner as the stalk
and the roots press against the collet^ of a plant. Haller thinks it is caused
by the pulsations of the nutritious arteries which penetrate into the long
bones, at their middle part; why then is their structure different at their
extremities where they receive arteries equally large and more numerous?
In the process of ossification, this substance appears first in the centre of
the longbonesj; and this confirms the assertion of Kerkringius, whosays,
that our long bones begin to ossify, in those points where they have to
resist the greatest pressure.

The spongy substance is found within the short bones, and at the ex-
tremities of the long ones, where'its accummulation is attended with two
advantages, that of giving to the bone, without increasing its weight, a
considerable size, by which it may be articulated with the neighbouring
bones, by wide surfaces, so as to give firmness to their connexions; this
confirmation is attended with another advantage, that of avoiding the pa-
rallelism of the tendons which pass over the joints, in order to enlarge
the angle of their insertion in the bones, and to give more efficacy to mus-
cular action. The mechanical hypotheses proposed by Haller and Du-
hamel, to explain the formation of this spongy substance, are very unsatis-
factory, especially if it be considered, that in the gelatinous bones of the
embryo, the place that is to be occupied by the spongy substance, viz.
the extremities of the long bones, of which the rudiments begin to ap-

* By chemical analysis of the bones, there have been discovered several other saline
substances mixed with the phosphate of lime ; but as this salt alone constitutes the
greatest part of the substance which gives to the bones their hardness, it has been par-
ticularly adduced. For an account of the chemical constitution of the osseous, texture,
see the Chapter at the end ot the APPENDIX — Copland.

f The part where the stem joins the root. — Trans.

* See APPENDIX, Note H H

2 U

338

pear, are larger than any other part. All the cells of this spongy sub-
stance communicate with one another, they are lined by a very fine mem-
brane, and contain the medullary fluid. The lamina which cross each
other, in various directions, and which form the parietes of the cells, be-
come fewer in number, and thinner; the spongy tissue expands in ap-
proaching the middle part of the bones, and forms (within the medullary
canal, of the compact substance) a reticular tissue, the use of which is
to support the membranous tube containing the marrow.

These three substances, notwithstanding their unequal denstiy, are, in
reality, but one and the same substance differently modified. The reticu-
lar and spongy differ from the compact, in containing less phosphate of
lime, and in having rarer and more expanded tissue. In other respects,
those changes in the osseous tissue which constitute the laminated exos-
toses, the conversion of the bones, by acids, into a flexible cartilage,
which, by maceration, may be reduced into cellular tissue, prove that these
three substances are truly identical, and differ from each other only by
the degrees of closeness of their texture and the quantity of calcareous
phosphate deposited in the meshes of their tissue.

The compact substance appears to consist of concentric lamina strong-
ly united together, and to be formed of fibres, arranged longitudinally,
and in juxta position. In proof of this arrangement, it is usual to men-
tion the exfoliation of bones to the air; but these lamina detached from
an exfoliating bone, merely prove that the action of the disease, the air,
heat, or any other agent, by applying itself successively to the different
layers of bone, produces between a separation which did not exist in
health, and determines their falling off in succession. Certain parts, in
which this lamellated structure does not exist, may, in like manner, un-
dergo the same kind of decomposition. Thus, Lassone saw a piece of
human skin that had been preserved, for a considerable length of time
in a vault, separate into layers of extreme minuteness.

The vital principle which exists, in a smaller degree, in the bones than
in other parts, seems to animate, to a certain degree, their different sub-
stances. Proportioned to the number of vessels which arc distributed
to it, life is more active in the spongy tissue; hence, in fracture of this
part, fleshy granulations and callus form more quickly. Caries, like-
wise advances more rapidly, and it is more difficult to interrupt its
progress.

CLXXVII. Of the uses vf the jieriosteum and of the medullary juices.
Whatever be the situation, the size, the shape^ and the composition of
bones, they are all eveloped by the periosteum, a whitish, fibrous, dense
and compact membrane, to which are distributed the vessels which pe-
netrate into their substance. The periosteum is a membrane perfectly
distinct from the other soft parts, and from the bone itself, to which it
adheres by means of vessels and of cellular tissue, which pass from the
one to the other, the more closely, as we are advanced in years. The
cellular and vascular fibres which penetrate into the substance ofthe bone,
establish a very close sympathetic connexion between its periosteum and
the very delicate membrane that lines its internal cavity, which secretes
the marrow, and is called the internal periosteum. On destroying the
internal medullary membrane, by introducing a stylet within the cavity
of the bone, its external layers swell, are detached from the inner ones,
and form, as it were, anew bone around the sequestra. The new bone is
not formed by the ossification of the periosteum, as was maintained by

339

Troja. This membrane has no more to do with the formation of the
new bone, in necrosis, than with that of the callus in fracture*. The pe-
riosteum, covering a bone affected with necrosis, does not become thick-
er, and does not acquire more consistence ; nor is there formed around
the ends of a fractured bone, a ring to keep them cemented, as was the
opinion of Duhamel ; an opinion recently brought forward in a work in
which the author seems to delight in reviving errors that have been aban-
doned for ages. Destitute of nourishment, (lead and dried up in this ar-
tifical necrosis, the sequestra moves in the centre of the new osseous
production, from which it may be extracted by a perforation made for
that purpose. It is owing to the same sympathy, that the dull noc-
turnal pains which are occasioned by the warmth of the bed, in patients
in the last stages of the venereal affection, and which appear to have their
seat in the centre of the long bones, occasion a swelling of these bones
and of the periosteum.

The use of the periosteum is to regulate the distribution of the nutri-
tious juices of bones, since, whenever it is removed, granulations arise,
in an irregular manner, on the spot that is bared. This quality is, be-
sides, common to all fibrous membranes whose destruction is followed by
excrescences from the organs which they cover. The same take place,
whenever trees are partially stripped of their bark. It has been errone-
ously believed, that the periosteum, in the same way as the bark of plants,
contributes to the growth of the bones, by the successive induration of
its internal lamina.

The marrow which tills the central cavity of the long bones ; and the
medullary fluid contained in the cells of the spongy substance, bear the
greatest analogy to adeps, both in their chemical composition and in their
uses (CVI.) The proportion of these two fluids is uniformly relative.^—
In very thin people, the bones contain a marVow that is thin and watery,
and though this fluid always fills the internal cavities of these .organs,
whose solid parietes cannot collapse, it contains much fewer particles in
the same bulk ; and its quantity like that of the fat, is in fact diminished.
It is the product of arterial exhalation, and does not serve to the imme-
diate nutrition of the bone, as was thought by the ancients ; at least, it
does not answer the purpose solely, for, in the numerous class of birds,
the bones contain cavities for air, and are destitute of this fluid. It is dif-
ficult to determine the use of the marrow and of the medullary fluid :
may they not answer the purpose of filling the cavities which Nature has
formed in the bones, so as to render them lighter ? Does a part of these
fluids exude through the cartilages of the joints, and mix with the syno-
via to increase its quantity: and to lessen the friction of the articulating
surfaces ? If this transudation may take place after death, why might it
not take place, when all the parts are in a state of vital warmth and ex-
pansion! ?

* The manner in which the new bone acquires a periosteum, in cases of the regene-
ration of this texture, is a matter of much interest and doubt. In the examination of
some specimens, Dr. Knox observed a thin membrane covering1 the osseous granulations;
but he knew of no facts to decide whence the membrane proceeds. " It is not unlike-
ly," he remarks, "that it is supplied by the cellular texture either of the new bone, or
of the surrounding- parts ; and that in some instances it may be merely a prolongation of
the old. New skin on ulcers does not always grow from the surrounding1 healthy edg-
es : — which fact may be applied to the formation of new periosteum." — Copland.

f The marrow of the bones is contained in the medullary membrane. This latter sub-

340

CLXXVIII. Of the articulations, the articulating cartilages and liga-
ments^ and the synovial fluid. The articulations of the different parts of
the skeleton are not all intended to allow of motion, several, as the ser-
rated and squamous sutures, and the gomphosys, are entirely without
motion, and are, on that account, termed synarthrosis. All the other ar-
ticulations, whether the bones are in immediate contact (diarthrosis of
contiguity,) whether they are united by a substance interposed between
them (diarthrosis of continuity or amphiarthrosis,) are endowed with a
certain degree of mobility. I shall speak merely of the moveable articu-
lations ; whether they allow of extensive motions and in every direction
(diarthrosis orbicularis,) or whether the bones move only in two opposite
directions (alternate diarthrosis or ginglymus,) by forming an angle (an-
gular ginglymus,) or by executing, on each other, motions of rotation
(lateral ginglymus.)

In all the articulations, the osseous surfaces are covered by lamina of
a substance less hard than that of the bone. These are the articulating
cartilages which answer the two purposes of giving to the ends of the
bones, the degree of polish necessary to their slipping freely, and to fa-
cilitate motion, by the considerable degree of elasticity which they pos-
sess. Morgagni has shown, that of all animal substances, cartilages pos-
sess most elasticity ; their sturucture is very different from that of the
bones, even when these are yet cartilaginous; for, these articulating car-
tilages do not become ossified, even in persons greatly advanced in
years*. They are formed of very short fibres disposed according to the
length of the bone, strongly compressed against each other, and united

stance may be easily detached from the bone. It resembles, in some respects, a cob-
web, being pierced by a number of holes. It is formed of cellular tissue, and of vessels.
The former is very delicate and rare ; and evidently performs the function of furnish-
ing a surface for the ramification of the vessels. Some of these vessels are ramified ex-
ternally, proceeding directly from the medullary membrane to the osseous texture sur-
rounding' it, and thus performing the office of an internal periosteum to the bone; —
others are distributed internally, and in the direction of the axis or the bone, to the me-
dullary membrane itself, and to the spongy extremities of the bones. The principal
artery of the medullary canal is surrounded by absorbent vessels at its entrance into this
canal. A plexus of nerves may be also observed to surround the artery in the same situ-
ation, and to dip into the bone at the place nearest to the arterial trunk.

The adipose vesicles, which contain the marrow and occupy the interior of the medul-
lary membrane, are the same in kind as those of the cellular texture, although less dis-
tinct. Authors have long since considered that those adipose vesicles are united en
grappt, and may believe that they communicate with eacli other.

M. BECXAKD considers the marrow to consist of seven parts out of eigl it of an oleagin-
ous matter, in fat subjects, which inference accords with the opinion of of GUUTZMACHEII;
while this substance, in a phthisical patient, was found to consist of only a fourth part
of fatty matter, the rest being a serous, or albuminous-like fluid.

The marrow does not exist in the fostus, and even the medullary mebrane itself can-
not be recognised previous to ossification. As this process advances, the medullary ca-
nal begins to be formed ; and at first the nutritious artery nearly fills it. At a later pe-
riod this artery is seen ramified on the parietes of this cavity, and in the situation of the
medullary membrane. The marrow becomes abundant as age advances, owing to the
enlargemeut of the medullary cavity.

The sensibility of the marrow, which was contended for by DCRVSRIVEY, but since de-
nied, is considered by M. BKCLARD really to exist, and to be satisfactorily shown, when
some time is allowed to ellipse between the pain of the operation necessary to expose
the marrow, and the experiment to which it is to be subjected.

See APPKNDIX, Note H H, for additional remarks on this subject. — Copland.

* Sometimes, however, these cartilages are destroyed, the denuded bone then becomes
polished by friction, and as hard as ivory. — Copland.

341

by other transverse fibres. This verticle direction of the greatest pan
of cartilaginous fibres, demonstrated by Lassone, is very favourable to
their elastic re-action. The capsular ligament is reflected over them, be-
comes very thin, and is lost in their perichondrium, according to Bonn,
Nesbit, and other anatomists.

Besides the cartilages which surround the extremities of bones, there
are found, in certain articulations, fibre-cartilaginous lamina lying be-
tween the articulating surfaces. These connecting ligaments may be ob-
served in the articulation of the lower jaw to the temporal bones, of the
femur with the tibia, and of the sternum with the clavicle ; and all such
articulations perform a great number of motions, as is the case with the
jaw, or suffer considerable pressure, as the joints of the knee and sternum.
The latter, which has a very slight degree of motion, being the point in
which terminate all the efforts of the upper extremity, required this ap-
paratus to lessen the effect on the trunk, the motion that is given, being
in part, lost, in the action of the articulating cartilage*.

I shall.'not repent what has been already said of the secretion of the fluid
that lubricates the articulating surfaces, that facilitates their motion, and
keeps them in contact. Its quantity is in direct ratio to the extent of
these surfaces, and of the membranous capsule in which they are contain-
ed ; it is likewise, proportioned to the frequency of motion which each
articulation allows.

Synovia is the name that is given to the fluid prepared by the glandule-
cellular bodies in the vicinity of the articulations, and secreted by the
membranous capsules which surround them, and are reflected over the
articulating extremities of the bones whose cartilages they cover ; so that,
as was shown by Bonn, about the middle of the last century, these extre-
mities cannot be said to be contained within the cavity of the capsule,
which is closed in every direction, any more than the abdominal viscera
within that of the peritoneum. The synovia is heavier than common wa-
ter, quite cojourless, and more viscid than any other animal fluid. It
contains a considerable quantity of albumine, which, according to Mar-
gueron, who first gave a tolerably accurate analysis of synovia, it is found
in a particular state, and much disposed to concrete in to filaments, on the
addition of acids.

Besides, it contains muriate and carbonate and phosphate of lime,
the whole dissolved in water, which forms about three-fourths of its
weightf.

CLXXIX. Theory of Anchylosis. Motion may be considered as the
proper stimulus of the synovial secretion; and a moveable joint, as is just-
ly observed by Grimaud,is as a centre of fluxion towards which the fluids
rush, in every direction, in consequence of the irritation which friction
determines. If the joint remains long without motion, the synovia is se-
creted in smaller quantity, and this lessens gradually : it may even hap-

* The most certain proof of the organic nature of the cartilages is the serous exuda-
tion which appears in the course of a few seconds after a clean division of them by the
knife. Cellular texture forms the mould or basis in which the cartilaginous substance is
deposited. The vessels of this texture carry only the colourless part of the blood into
it, during its ordinary state of health; yet it is remarkable that other colouring substan-
ces, as bile and madder, give this substance their respective colours — Copland.

| See the Chapter on the Chemical Constitution of the Secretions, &c. at the end of
the ApBExmx. — Copland.

342

pen that the articulating1 surfaces remaining long and absolutely motion*
less, lose their moisture, and from the want of the fluid which should lu-
bricate .them, bring on irritation and adhesive inflammation in each other,
either from increased action of the vessels of the perichondrium, or
as is believed by Nesbit, Bonn, and others, from an inflammatory state
of the fold, which is reflected from the capsule ot the joint over the liga-
ment.

This is the manner in which the disease, termed anchylosis, comes on,
a disease improperly ascribed to the congestion of the soft parts, and es-
pecially of the ligaments surrounding the articulations. In fact, when in
a fracture of the thigh or leg, about the middle of the length of one of
these bones, and consequently, at the greatest possible distance from the
knee joint, the circumstances of the case require that the bandages should
be kept on the limb, a considerable time, the joint loses its power of mo-
tion, recovers it with difficulty, and sometimes not at all. I have at
present before me, the case of a man in whom a scorbutic affection has
delayed, to such a degree, the union of the bone, after a simple fracture
of the femur, about the middle of the bone, that it has been found neces-
sary to continue, for seven months the use of splints. In the course of so
long a state of inaction, the soft parts have lost the habit of moving, and
the knee is almost completely ancholysed.

Whenever, on account of any complaint, one has been confined to bed,
the first attempts to walk are painful, difficult, and attended by a marked
crepitus in the knee, denoting clearly the want of synovia. On the other
hand, if the joint is examined in a person who before death has been
Jong without motion, the articulating surfaces will be found rough and
dry, with evident marks of iuflammation. Flajani mentions the case of a
patient who died after having been three months in bed, in an almost mo-
tionless state. Externally, the knees did not appear to have been injur-
ed, and yet he could not bend his knee joint. On opening the joint, it
was found that the articulating surfaces had grown together ; the poste-
rior part of the patella adhered to the condyles of the femur, and it was
necessary to use a scalpel to detach these parts from each other. I have
frequently observed the same appearance in dissecting the knee joint of
persons who died while labouring under white swelling, with or without
ulceration. The anchylosis which invariably attends this affection, evi-
dently arises from the absolute rest of the diseased joint.

Anchylosis from want of motion, and consequently from want of syno-
via, is not always a partial affection limited to one or two joints ; some-
times, it affects several at once, as in the case of the patient whose skele-
ton was presented by M. Larrey to the museum of the School of Medi-
cine at Paris. One of the most remarkable cases. of universal anchylosis
of the joints, is that lately communicated to the National Institute by M.
Percy; the patient was an old cavalry officer, who was subject to fits of
the gout, and whose articulations, even that of the lower jaw, became stiff
and completely lost all power of motion, so that, towards the latter end of
hiy wretched existence, he could notbe moved without feeling severe pain
in his ancholysed joints.

From this explanation may be conceived the advantage of moving the
lower extremity, when, after a fracture of the leg, the ends of the bone
have become sufficiently united lo prevent their being displaced. These
motions, which are of indispensable necessity in all fractures of the fe-
mur, of the tibia, and especially of the patella, are much better calculated

343

to prevent anchylosis, than the various resolvent remedies which are com-
monly employed, as plasters of soap, vigo, cicuta, drabotanum, diachylon,
pumping, bathing, and fumigations, which, however, should be used in
combination with a moderate exercise of the limb, in order to obtain the
most complete success.

The gout affects those joints whcih are most subject to motion, and on
which there is the greatest pressure. The first attacks, as Sydenham
observes, come on in the joint of the great toe with the first metatarsal
bone, an articulation which bears the weight of the whole body, and
which is most called into action, in the various motions of progression.

The muscles which pass over the joints give them much greater secu-
rity than the lateral ligaments. In fact, if the muscles become palsied,
the mere weight of the limb stretches the ligaments, which give way be-
come elongated, and allow the head of the bone to escape from its gle-
noid cavity. It is, in this manner, that a loss of motion, and atrophy of
deltoid muscle, are attended with a luxation of the humerus: the orbicu-
lar ligament of the articulation of this bone with the scapula, being in-
capable of retaining its head within the glenoid cavity. The spinal
column, when dissected and deprived of all but its ligamentous attach-
ments, gives way under a weight much smaller than that which it would
have supported, before being stripped of the muscles which are connect-
ed with it.

CLXXX. Of standing. This is the name given to the action by which
man holds himself upright on a solid plane. In this erect position of all
our parts, the perpendicular line passing through the centre of gravity*
of the body, must fall on some point of the space measured by their soals
of the feet. Standing is most firm when on prolonging the line of the
centre of gravity of the body, it falls on the base of sustentation (I call
thus the space defined by the feet, whether close or apart;) but this line
may tend to exceed it, without our necessarily falling, the muscular ac-
tion soon restoring the equilibrium which is deranged by the altered di-
rection of this line. But if the lower extremity of the line, by being pro-
longed, should fall without the limits of the base of sustentation, a fall is
unavoidable on the side towards which this line inclines!.

If the body is inclined backwards, so that there is a danger of a fall on
the occiput, the extensor muscles of the leg contract powerfully, to pre-
vent the thigh from bending, while other powers bring forward the up-
per parts, and give to the prolonged line of the centre of gravity a differ-
ent direction; and if in proportion as the extensors of the leg are brought
into action, its inclination be increased to such a degree that nothing is
capable of keeping up the body, which its own weight tends to bring to
the ground, these muscles, by a motion proportioned to the quickness of
the fall, will increase their efforts to prevent it, and may be able, in that
violent contraction, to snap asunder the patella, as I have explained in a
Memoir on the fractures of that bone.

* The centre of gravity, in the adult, is situated between the sacrum and pubis.

f ' ' Quotiescitmque linea propensionis coi^poris humani ccu<:t t>xtra WMIS peitis innixi
plantam, out extra yuadrilaUrum, comprehension a ditabus plantis pedum, impediri ndna,
a q-uocumquK musculorwn coaatu, non potest." Borelli. Prop. 140.

The firmness of the attitude, in standings, depend, therefore, in part, on the breadth
of the feet and on their distance ; hence, it is much more tottering when we stand on
one foot, and we are, under such circumstance, obliged to be perpetually struggling-,
to prevent the centre of gravity from falling out of the narrow limits of the base of sus-
tentation — Author's Note,

344

I think it useful to insist, more than has been done hitherto, on the me-
chanism by which the human body is supported in the erect posture; for
a knowledge of that mechanism facilitates the explanation of the motions
of progression. To walk, or to run, the body must be upright; now,
•when it is known by what power the centre of gravity of the body is main-
tained perpendicular on the plane which supports it, it will be easy to
understand the different ways in which it changes its place, in the course
of locomotion.

Let us first inquire into the question so long agitated, whether man la
intended to support himself and to walk on his four limbs, in the early
period of his existence after birth ?

CLXXXI. An upright position would be to man a state of rest, if his
head were in a perfect equilibrum on the vertebral column, and if the
latter^ forming the axis of the body and supporting equally, in every di-
rection, the weight of the abdominal and thoracic viscera, fell perpen-
dicularly on the pelvis placed horizontally, and, in short, if the bones of
the lower extremities formed columns set perpendicularly under their
superincumbent weight; but not one of these circumstances is to be ob-
served in the human body: the articulation of the head docs not corres-
pond to its centre of gravity; the weight of the thoracic and abdominal
viscera, and of the parietes of the cavities in which they are contained,
rests, almost entirely, on the anterior part of the vertebral column. The
vertebral column is supported on an inclined base, and the bones of the
inferior extremities, which are connected to each other by convex and
slippery surfaces, are, more or less, inclined towards one another. It is
therefore necessary, that an active power* watch incessantly, to prevent
the fall which would be the natural consequences of their weight and
direction.

This power resides in the extensor muscles which keep the parts of
OUP body in a state of extension, the more perfect, and which render our
erect posture the firmer, as they are endowed with a more considerable
power of antagonism, and as our parts arenaturally less disposed to flexion;
and, besides, as we have seen (CLXVI.) these powers are not sufficient
to balance those whose action is directly opposed to theirs.

The relative weakness of the extensor muscles is not the only obstacle
which renders impossible an erect posture, at an early period of life.
Other causes, into which we are about to enter, concur in unfitting the
new born child for the exercise of that faculty.

The articulation of the head to the vertebral column being nearer the

* An upright posture is not, in all animals, as it is in man, the consequence of an
effort. This is proved by the following fact, observed by M. Dumeril. The sea fowl,
and especially the waders (Grallae, Lin.) as the herons and storks, forced to live in the
midst of marshes and muddy waters, in which they find the fishes and reptiles, on which
they feed, have long since afforded matter of surprise to Naturalists, by the length of
time they can remain motionless in an erect posture. This singular power, so necessary
to animals obliged to expect their prey, mure from change than from industry, they owe
to a peculiar conformation of the arliculation between the leg- and the thigh. The arti-
culating surface of the thigh bone, as M. Dumeril had an opportunity of observing- in a
stork (Ardea ciconia, Linn.) contains, in its centre, a depression, into which there is re-
ceived a projection of the tibia. To enable the animal to bend its leg, that projection
must be disengaged from the depression into which it is lodged, and this is resisted by
several ligaments which keep the leg extended in standing, in flying, and other progres-
sive motions, without the assistance of the extensor muscles. — Copland.

.345

occiput than the chin, and not corresponding* to its centre of gravity, its
own weight is sufficient to make it fall on the upper part of the chest. It
is the more disposed to fall forward, from its greater bulk, and, as in a
new born child the head is much larger in proportion than the other parts
of the body, and as its extensor muscles partake of the greater weakness
of that set of muscles, it falls on the fore part of the chest, and its fall
draws the body after it. The weight of the thoracic and abdominal vis-
cera tends to produce the same effect.

Growth always proceeds from the upper to the lower parts, and this
law, which operates uniformly, completely eludes every kind of mechani-
cal explanation. It is otherwise, with regard to the effects which result
from this unequal growth in respect to the erect posture. The inferior
limbs, which serve as a base to the whole edifice being imperfectly
evolved at the period of birth, the upper parts placed on these unsteady
foundations must necessarily fall and bring them down with them.

The relative weight of the head, of the thoracic and abdominal viscera,
tends, therefore, to bring forwards the line in the direction of which all
the parts of the body press on the plane which supports it, and this line
should be exactly perpendicular to that plane to enable the body to be
perfectly erect: the following fact proves this assertion: I have observed,
that children, whose head is very large, whose belly projects, and Whose
viscera are loaded with fat, have much difficulty in learning to stand; it
is only about the end of their second year, that they dare trust to their
own strength, and then they meet with frequent falls, and have a con-
tinual tendency to go on all fours.

The vertebral column, in the child, does not describe, as in the adult,
three curves alternately placed, in opposite directions. It is almost
straight, and yet presents in the direction of its length a slight curvature,
the concavity of which looks forwards. This incurvation, which depends
solely on the flexion of the trunk while ;ri the womb, is accordingly more
marked, the nearer the child is to the time of its birth.

It is well known that the curvatures, in opposite directions to the ver-
tebral column, add to the firmness of the erect posture, by increasing the
extent of the space within which the centre of gravity may move, without
being carried Jbeyond its limits. With regard to that use, the vertebral
column may be considered, as defined by two lines drawn from the ante-
rior and posterior part of the first cervical vertebra, to the sacro lum-
bar symphysis. These two lines, very near to each other at their upper
part, and, below, at a distance from each other, would be the chords of
arcs and the tangents of the curves, formed by the vertebral column.
So that this column may be considered as having a fictitious thickness
greatly exceeding its real bulk.

In the new-born child, the want of alternate curvatures not only con-
tracts the boundaries within which the centre of gravity may be varied,
but the direction of the only curvature which exists favours the flexion
of the trunk, and consequently the inclination forward of the centre of
gravity, and the tendency to fall in that direction. This inflexion of the
vertebral column in the foetus and in the young child, resembles that ob-
served in several quadrupeds*.

* This curvature is very distinctly marked in swine. The back of these animals is
remarkably prominent, and this form, necessary to enable the vertebral column to sup-

2X '

34$

The disadvantages resulting from the want of alternate curvatures in
the vertebral column of the child, is further increased, by the total ab-
sence of spinous processes. It is well known, that the principal use of
these projections, is to place the power at a distance from the^ centre of
motion of the vertebrae, to increase the length of the lever by which it
acts in straightening the trunk, and thereby to render its action more effi-
cacious. At the period of birth, the vertebrae have no spinous processes,
they afterwards grow from the. place at which the lamina of those bones
are united, by means of a .cartilaginous substance, which completes
the posterior part of the vertebral canal. The muscles destined to keep
the trunk erect, weakened by its constant flexion during gestation, lose,
besides, a great deal of their power, from the unfavourable manner in
which they are applied to the part on which they .are to act.

The flexion of the head does not depend merely on its very considerable
\veight, but, likewise, on the want of spinous processes in the cervical
vertebrae; since the principal motions of the neck are performed, not so
much by articulation with the atlas, as by union of the other cervical
vertebrae.

The pelvis of the child is but imperfectly evolved, and its upper outlet
very oblique. The viscera, which are afterwards to be contained within
its cavity, are, for the greater part, situated above it. This obliquity of
the pelvis would require a perpetual straightening of the vertebral column
to prevent the direction of the centre of gravity from obeying its natural
tendency forward. On the other hand, the vertebral column resting on a
narrow pelvis, is less firmly fixed, and may more readily be drawn beyond
the limits of the base of sustentation. Lastly, the limited extent of the
pelvis, together with its obliquity, causes the ill supported abdominal
viscera to fall on the anterior and inferior part of the parietes of the ab-
domen, and favours the fall of the body in the same direction.

The patella, which answers the double purpose of giving firmness to
the knee joint, in front of which it is placed, and of increasing the power
of the muscles of the leg, by placing them at a distance from the centre of
motion in that articulation, and by increasing the angle at which they are
inserted into the tibia, as yet does not exist in new-born children. The
tendinous portion of the leg, where the patella is hereafter to be formed,
is merely of a more condensed tissue, and of a cartilaginous hardness.

The want of a fulcrum is attended with a continual disposition in the
leg to bend upon the thigh, and the parallel direction of its extensor
muscles, occasions a complete loss of their effective power. Then their
antagonizing muscles induce a flexion of that limb, which is the more
considerable, as it is but imperfectly limited by the tendon which is situ-
ated at the fore part of the knee.

The length of the os calcis, the extent of its projection beyond the in-
ferior extremity of the bones of the leg, tend to give firmness to the
erect posture, by increasing the length of the lever by which the ex-
tensors of the foot act on the heel, and, as, in the new-born child, this
bone is shorter and less projecting, the power of these muscles, whose

port the immense vv eight of their abdominal viscera, has a considerable influence on
the mechanism of their motions of progression. When frif htened by any noise, they
spring in bounds ; and it is easy to perceive, that, at each spring", the spine becomes
arched and then .straightens itself, and that their motion when rapidjs effected by the
alternate tension and relaxation of their spinal column. — JLuthvr's Note.

347

insertion is very near the centre of motion of the articulation of the foot,
is greatly diminished.

The feet, in man, are broader than those of any other animal; and to
this breadth of the surface of the base on which he rests, he, in great
measure, owes the advantage of being able to support, on one leg or on
both, the weight of his body, in standing and in the different motions of
progression ; while ,the other mammalia cannot support themselves, at
least only for a very limited time, without resting on three of their extre-
mities. When I say, that from the extent of the feet the body of man
does, of all animals, rest on the broadest surface, I do not take into ac-
count the space which those parts include between them when apart from
each other. In fact, the space which is measured by the feet, is much
greater in quadrupeds than in man. Nature has made up for the disad-
vantage arising out of the smallness of their feet, by the distance at which
they are placed ; and if that farm disables them from standing on two
feet, it gives firmness to their peculiar mode of standing.

The feet of the ourang outang, which, in the general structure of his
organs, bears so striking an analogy to the human species, resemble a
coarsely formed hand, better fitted to climb the trees on which that ani-
mal seeks his food, than to the purposes to which man applies his hands.
Thus, the erect posture which he, at times, assumes, is neither the most
convenient nor the most natural to him. And, according to a philosopher
who speaks on the authority of several travellers, if a sudden danger
obliges him to make his escape, or to leap, he drops on all fours, and dis-
covers his real origin: he is reduced to his own condition, when he quits
that unnatural attitude, and discovers in himself an animal, which, like
many a man, has no better quality to recommend him than a specious
disguise.

The feet are the parts least developed in the new-born child; his body
is insecure on that narrow basis; the prolongation of the line of his centre
of gravity, which so many other causes tend to carry beyond that base,
will be the more inclined to fall beyond it, from its small extent. The
greater number of the differences which have just been examined, depend
on the mode of nutrition in the foetus. The umbilical arteries bring to
the mother the blood which the aorta carries to the lower parts, and only
a few small branches are sent to the pelvis and to the lower extremities.
Thus, the developtment, which almost always bears a proportion to the
the quantity of blood sent into organs, is but imperfect in those parts at
the time of birth, while the head of the trunk and upper extremities are
enveloped much more considerably.

The new-born child, therefore, resembles quadrupeds in the physical
arrangement of his organs. This analogy is the more marked, the nearer
the foetus is to the period of its formation, and it might be laid down as
a general proposition, that organized beings resemble one another more
closely, the nearer to the period of incipient existence they are examined.
The differences which characterise them become apparent, in proportion
to the progress of evolution; and they are more and more distinct, as the
acts of life are repeated in the organs which it animates.

The unequal distribution of power in the muscles, and the unfavoura-
ble disposition of the parts to which these powers are applied, render it
impossible for the infant to stand upright, that is, to keep the mean line
of direction of his body nearly perpendicular to the plane which supports
it. But in proportion as he advances in age, the preponderance of the

348

flexors over the extensors ceases to be in excess. The proportionate size
of the head and of the thoracic abdominal viscera diminishes. The cur-
vatures of the vertebral column begin to be distinguishable, the spinous
processes of the vertebrae are evolved; the breajdth of the pelvis is in-
creased, and its obliquity lessened; the patella becomes ossified, the os
calcis juts out backwards, the relative smallness of the feet ceases. By
degrees the child learns to stand, resting on both or only on one of his
feet; his eyes natu tally directed towards heaven, a noble prerogative,
which, if one might believe Ovid*, is possessed by man alone of all the
animals.

Man is of all animals the only one that can stand upright and walk in
that attitude, when his organs are sufficiently evolved. Let us now point
out some of the principal causes to which that privilege is to be ascribed.

CLXXXII. Though the articulation of the head to the cervical column
does not correspond either to its centre of magnitude, or to its centre of
gravity, and though it is nearer to the occiput than to the chin, its dis-
tance tfrom the latter is much smaller in man, than in the monkey and
other animals, whose foramen magnum is, according to Daubenton,
placed nearest to the posterior extremity of the head, when they resem-
ble man the least. The head, therefore, is very nearly in equilibrio on
the column which supports it; at least to keep it in that position, a very
slight power is required, while the head of a quadruped, which has a
constant tendency towards the ground, requires to be supported by a part
capable of a great and continued resistence. This purpose is answered
by the posterior cervical ligament, so remarkable in those animals, at-
tached to the spinous processes of the vertebrae, and to the protuberance
of the occipital bone, which projects much more in them than in the
human species, in whom instead of the posterior cervical ligament, there
is found a mere line of cellular substance, dividing the nape of the neck
into two equal parts.

The alternate curvatures of the vertebral column, the breadth of the
pelvis and of the feet, the great power of the extensors of the foot and
thighf, all these favourable conditions, observable in man, are wanting in
animals; but, as in the latter, every thing concurs to prevent their be-
ing capable of standing on two feet, in man every thing is so disposed,
as to render it very difficult for him to rest on his four extremities. In
fact, independently of the great inequality which there is between his up*
per and lower limbs, a difference of length which, being less sensible in
early life, makes it less uneasy for a child to walk on his hands and feet,
these four limbs are far from affording the body an equally solid support.
The eyes being naturally forwards, are, in that attitude, directed towards
the earth, and do not embrace a sufficient space.

We cannot, therefore, agree with Barthez, that man, during infancy,
is naturally a quadruped, since he is then but an imperfect biped ;

* Os he-mini sublime dedit, calwnque tueri
Jnssi:, et ereclos ad sidtra toll-re vultus.

These verses may be much more justly applied to the fish, called by naturalists Uran-
oscopus. Its eyes are turned \ip\vards, and constantly look towards the heavens. — Au-
thor's JV0fe.

j- These masses form the calf of the leg and the buttocks , in no animal are these
muscles more prominent than in man.

349

(CLXXXI.) nor can we admit that man might walk on all fours all his
lite, if he were not broken of the bad habit which he learns in infancy.

CLXXXII1. Very little has been added to what Galen has said in his
admirable work of the structure of parts, relative to the respective ad-
vantages attending the peculiar conformation and structure of the upper
and lower limbs. It is easy to see, that in combining, as much as pos-
sible, strength and facility of motion, Nature has made the former pre-
dominate in the structure of the inferior extremities, while she has sacri-
ficed strength to facility, to precision, to extent, and rapidity of motion,
in the upper extremities.

To convince one's self of the truth of what has been stated, it is suffi-
cient to compare, under the two relations* of the resistance of which
they are capable, and of the motions which they allow, the pelvis to the
shoulder, the thigh to the humerus, the leg to the fore arm, and the foot
to the hand.

The inferior extremities, if examined when the bones are covered with
the soft parts, will present the appearance of an inverted cone or pyramid,
which, at first sight, appears contrary to the object which Nature had in
view; but if the bones be stripped of their fleshy coverings, these solid
supports will be seen to represent a pyramid, whose base is at the lowest
part, and formed by the foot, and which decreases in breadth upward
from the leg, formed by the union of two bones, towards the thigh, con-
sisting of only one bone.

If it be asked why the inferior extremities are formed of several pieces,
detached and placed one above the other, it will be found that they are
thereby much more solid, than if formed of one bone, since, according to
a theorem, demonstrated by Eulerf two columns containing the same
quantity of matter, and of equal diameter, have each a solidity in inverse
ratio of the squares of their height; in other words, of two columns, con-
taining the same materials, of equal diameter, and of unequal height, the
smaller is the stronger.

The long bones, which by their union form the inferior extremity, con-
lain a cavity which adds to their strength, for, according to another theo-
rem, explained by Galileo, two hollow columns of the same quantity of
matter, of the same weight and length, bear to each other a proportion of
strength measured by the diameter of their internal excavations.

The breadth of surface of the articulations of the inferior extremities,
assists, materially, in giving them additional strength, when in standing^
these bones are in a vertical direction. No articulation has a broader

* See the anatomical observations on the neck of the thigh bone, which I have pre-
fixed to a memoir which bears the title of Dissertation anatorrdco-chimrgicale sur Ics frac-
tures du col de femur. Paris an VII.

•}• J\lelhodiis inrt-.nientli Eneas citrvas.

Nature has, therefore, increased the number of these columns in the extremities of
quadrupeds, by raising their heel and the different parts of the foot, whose bones she
has lengthened, to make of them so many secondary legs. These numerous columns
placed above one another, are alternately 'inclined, and in a state of habitual flexion, in
the quadrupeds remarkable for swiftness in running, or for their power in leaping, as in
the hare and squirrel, while in the ox, and especially in the elephant, they are ,all placed
vertically, so that the enormous mass of the latter rests on four pillars, the different
pieces of which are short, and so slightly moveable on one another, that, as Barthex.
observes, Saint Basil has adopted the error of Pliny, JElian, and several other wri-
ters of antiquity, that there are no articulations in the legs of that monstrous animal-
— Author's Note.

350

surface than that of the thigh with the leg and knee-pan. Among the
orbicular articulations, no one has more points of contact than the joint
of the thigh bone to those of the pelvis. Professor Barthez says, that
when the body is erect, the head of the thigh bone and the acetabulum of
the os innominatum, which receives that bone, come in contact in a sur-
face of small extent. I am, on the contrary, of opinion, that in no pos-
sible case can the contact of two bones be more complete. The middle
line of direction of the upper part, the thigh bone, is then exactly perpen-
dicular to the surface of the comlyloid cavity, which embraces and
touches, in nearly every point, the almost spherical head of that bone.

The cervix'on which the head of the bone is placed, by keeping the
thigh bone at a distance from the cavity of the pelvis, increases the ex-
tent of the space, in which the centre of gravity may vary without being
carried beyond its limits.

CLXXXIV. The erect posture does not imply a perfect absence of
motion. It is on the contrary, accompanied by a staggering, which is
the more marked in proportion as the person has less strength and vig-
our.— These perpetual oscillations, though but slightly distinct, in a man
who stands upright, depend on the incapacity of the extensors to keep
up a constant state of contraction, so that they become relaxed for a short
time, and the intervals of rest in the extensors are frequent, in proportion
to the weaker state of the subject.

Some physiologists have given a very inaccurate idea of standing, by
making that attitude depend on a general effort of the muscles ; the ex-
tensors only are truly active. The flexors, far from assisting, tend, on
the contrary, to disturb the relation between the bones, necessary to ren-
der that state permanent. This explains, why standing is so much
more fatiguing than walking, in which, the extensors and flexors of the
limbs, are in alternate action and rest.

It may be said, nevertheless, that to give the greater firmness to the
attitude, we sometimes contract, in a moderate degree, the flexors them-
selves ; then, that great part of the real force of the muscles, which acts
according to the direction of the levers which they are to set in motion
(CLXVI.) and which rs completely lost in the different motions which
they produce, is usefully employed in drawing together the articular ex-
tremities, in keeping their surfaces firmly applied to each other, and in
maintaining their exact superposition which is necessary to the erect
posture of the body. No one that I know of, had taken notice of this
employment of the greater portion of our muscular power, which was
thought completely lost by the unfavourable arrangement of our organs
of motion. The line, according to which all the parts of the body bear
on the plane which supports them, has much more tendency to fall for-
wards than backwards*; and falls forward are the most common and
the easiest. Thus, nature has directed, in the same direction, the mo-
tion of the hands, which we carry forward to break the force of our falls,
to prevent too violent shocks^ and to lessen their effect. At the same
time, she has provided means of protection towards the sides which the

* This tendency is much less distinct in tall slender men. It is observed, that they,
for the most part, stoop in walking, less from the habit of bending- forward, than to pre-
vent the centre of gravity from falling- behind. Pregnant women, dropsical patients,
all persons who have much corpulence throw their body back, from an opposite and
easily understood reason. — Copland.

kands couid not guard. She has given more thickness to the back part
of the skull; the skin which covers the neck and back, is much denser
than that which covers the fore part of the body. The scapula, in addi-
tion to the ribs, protects the posterior part of the chest. The spinal
column lies along the whole length of the back ; the bones of the pelvis
have their whole breadth turned backward.

Falls are the more serious, as they occur in a more perfect statew of
extension of the articulations; the falls of a child whose limbs are in an
fiabitual state of flexion, are much less dangerous than those of a strong
and powerful adult, whose body falls in one piece, if I may be allowed
that expression. The falls which skaiters meet with, on the ice, are often
fatal from fracture of the skull, which, placed at the extremity of a long
lever formed by the whole body, whose articulations are on the stretch,
strikes the slippery and solid ice, with a momentum increased by the
quickness of the fall.

We have already seen, that wading fowls remain a long while standing,
without effort, by means of a peculiar contrivance in the articulation ot'
the tibia to the thigh bone, but all other birds are obliged to employ mus-
cular action when standing, except during sleep. The greater part, it is
well known, roost on a branch which they grasp firmly with their claws.
Now, this constriction, by which they cling to their support, is a neces-
sary result of the manner in which the tendons of the flexors of their feet
descend along their legs. Tnese tendons pass behind the articulation
of the heel; a muscle which arises from the pubis joins them, as it passes
in front of the knee, so that the bird has but to give way \p his weight,
and the joints, becoming salient on the side along which the tendons run,
stretch and pull them, and make them act upon the feet, so as to draw in
the claws to clasp tightly the braneh on which he is perched. Borelli
was the first who understood distinctly and explained satisfactorily this
phenomenon*.

CLXXXV. Although standing on both feet is most natural to man, he
is able to stand on one ; but the posture is fatiguing, from the forced in-
clination of the body to the side of the leg which supports him, and the
effort of contraction required to keep up this lateral inflexion. The dif-
ficulty increases, if, instead of resting on the entire soal, we choose to
stand on the heel or on the toe: the base of support is then so small, that
no effort is sufficient to keep the centre of gravity, long together, in the
requisite situation.

As to the degree of separation of the feet, which gives the firmest pos-
sible stand, it depends upon their length. When they inclose a perfect
square, that is, when taking their length at nine inches, each side of the
quadrilateral figure is of that measure, the stand is the firmest that can
be conceived. Nevertheless, we are far from keeping or taking this pos-
ture to prevent falls. The wrestler who wants to throw his antagonist,
strides much more; but then, he loses on one side what he gains on ano-
ther ; and if he stride thirty-six inches, on the transversal line, it will
need much greater force to overthrow him on that side ; but it will take
much less to throw him forwards, or on his back. Wherefore, one
of the great principles of this gymnastic art, is to bring back the feet

T)e motu dnimaUum, Prop. 150. Qn&rimr qitare aves stando, ranus arborum compre.
hemis, qui-esrnnt et dormiunt absquc ruina. Tab. II. fig. 7-

to a moderate stride, in the line of the effort which is foreseen to require
resistance.

There is some resemblance to standing, in the attitudes of kneeling
and sitting.

In the first, the weight of the body bears upon the knees, and we must
bring back the body, to throw the centre of gravity over the middle of the
legs. Accordingly, if we have nothing before us to lean on, this posture
is extremely distressing, and we cannot long keep it on. I have said, in
another work, that genuflexion rendered monks very liable to hernia; the
abdominal viscera being pushed against the anterior and lower part of
the abdomen, by the throwing back of the body.

In sitting, the weight of the body bearing on the tuberosities of the
ischia, there is much less effort required than in standing on the feet.— •
The base of support is much larger ; and when the back leans, almost
all the extensor muscles employed in standing, are in action.

CLXXXVI. Of Ike recumbent jiosture. Decubitus. All the authors
who, like Borelli, have treated professedly of the animal mechanism; all
the physiologists, who, like Haller, have set forth, in some detail, the me-
chanism of standing, and of progression, have completely passed over the
consideration of the human body in repose, left to its own weight, in ly-
ing on an horizontal plane. The intention of the following observations
is to fill up this gap. Let us consider, at setting out, that lying on an
horizontal plane, is the only posture in which all the locomotive muscles
recover the principle of their contractility, exhausted by exertion. Stand-
ing whhout motion, has only the appearance of repose, and the unremit-
ted contractions it requires, fatigue the muscular organs, more than the
alternate contractions, by which the various motions of progression are
carried into effect.

The human body, stretched on an horizontal plane, reposes in four po-
sitions ; as it lies on the back, the belly, or one or other of the sides".
The Latin tongue expresses the first two situations, by the terms supine
and prone*- It has no particular word for lying upon the sidef.

Lying upon the right side is the most ordinary posture of sleep, in
which we rest most pleasantly, and longest together. There are very
few, except under constraint of some faulty organization, who lie on the
other side. This depends on two causes; when the body lies on the left
side, the liver, a bulky viscus, very heavy, and ill steadied in the right
hypochondrium, presses with all its weight on the stomach, and draws
down the diaphragm : thence ensues an uneasiness, which hinders long
continuance of sleep, or disturbs it with distressing dreams : then the
human stomach presents a canal in which the course of its contents is
obliquely directed from above downwards, and from left to right: the
right or pyloric orifice of the stomach is much less raised than its left or
cardiac orifice ; lying on the right side favours, therefore, the descent of
aliments, which to pass into the intestines, are not obliged to ascend
against their own weight, as they must, in lying on the left side, i hese
two anatomical causes exert their influence on the generality of men, and
if there are any who fall into the habit of lying on the left, one may safe-

* Cubitus supinus, Plin. Cubitus pronus, Cicer. Cubare in faciem, Juven. Supinus
velpronus jucere.

f Dextro vel laevo hterc cubare ; cubitus in hitus. Plin'".

353

ly conjecture some vicious organization, or some accidental cause, that
determines them, as by instinct, to this posture,

Let us suppose an effusion of blood, water, or pus, in the sac of the
pleura of the right side. The patient lies on this side, that the weight of
his body may not oppose the dilatation of the sound side of the chest.-—
The parietes of this cavity are not equally distant from its axis ; the
pressure of the body on the plane of support, prevents the separation of
the ribs, whether as a mechanical hindrance to the displacement of these
bones, or in numbing the contractility of the muscles of inspiration, all
more or less compressed : Now, as the healthy lung must supply the
place of the diseased, nothing could be more in the way than to produce,
on that side, by a bad posture, a constraint equal to that occasioned by
disease, on the other.

It has long been imagined, and it is taught still, that, in thoracic effu-
sions, patients lie on the side of the effusion, to hinder the effused fluid
from pressing on the mediastinum, and pushing it against the opposite
lung, of which it will constrain the developement. The following ex-
periments show clearly enough the error of such a supposition :

I had several times produced artificial hydrothorax,. by injecting with
water, the chest of several bodies, through a wound in one of the sides.
This experiment can be made, only on bodies in which the lungs are free
from adhesion to the parietes of the chest, and the number is smaller than
might be imagined : you may introduce in this way from three to four
pints of water. I afterwards opened carefully the opposite side of the
chest: the ribs removed and the lung displaced, gave room to see dis-
tinctly the septum of the mediastinum stretched from the vertebral co-
lumn to the sternum, and supporting without yielding, the weight of the
liquid, whatever might be the posture given to the body*

It is for the sake then, evidently, of not preventing the dilatation of the
sound part of the respiratory apparatus, already condemned in one part
to inaction, that patients, in thoracic effasion, lie constantly on the side
of the effusion. It is for the same motive, to which we may add that of
not increasing the pain by dragging downward the inflamed pleura, that
patients in pleurisy lie on the affected side. The same thing happens in
peripneumonies; in a word, in all diseased affections of the lungs ant!
parietes of the chest*.

Lying on the back, which is unusual in health^ is natural in many dis-
eases. It commonly indicates more or less weakness of the muscles of
inspiration. The contractile powers which perform the dilatation of the
chest, when affected with adynamia, in fevers of a bad character, or after
extreme fatigue, carry very imperfectly into effect this dilatation. Ne-
vertheless, a determinate quantity of atmospherical air must be admitted,
every moment, into the lungs, and the general weakness would be in-
creased, if respiration did not impregnate the blood with a sufficiency of
oxygen : patients choose, therefore, the posture which makes the dilata-
tion of the lungs easiest for their weakened muscles. The posterior pa-
rietes of the chest, on which the body reposes, lying upon the back, are al-
most useless in the expansion of the cavity. The ribs, which have, the
centre of their motions in their articulations with the vertebral column,
are almost immoveable backwards, and the movsableness of these bones

* This is not the case until after adhesions of the pleurae have taken place.— 'Copland

354

increases with the length of the lever which they represent. So that, no
where is it greater than at the anterior extremity terminating in the
sternum. Thus, lying on the back has the double advantage of not con-
straining any of the muscles of inspiration, and of not opposing the mo-
tion of the ribs, except at that part where these bones have the least play:
lying on the back is one of the characteristic symptoms of putrid or ady-
namic fever, of scurvy, and of all the diseases of which debility of the
contractile parts forms the principal characteristic. After the fatigue
of a long march, or of any other continued exertion, we take this position
in lying, and change it, only when sleep has sufficiently replaced the loss
of contractility.

Lying on the belly has effects directly the reverse. The expansion of
the chest is hindered, exactly where the bony structure is formed for the
greatest play of motion : the abdominal viscera are besides pushed up on
the diaphragm, of which they resist the depression, and the posture is
accordingly unusual. The continuance of it during sleep is possible only
to the robust 5 others, even when they do fall asleep in this posture, soon
awake from troubled and distressing dreams, under the agony known by
the name of the night-mare. We sometimes seek this posture to constrain
respiration, and so abate inward excitation, in the ardour, for instance,
of a febrile paroxysm.

The different postures of lying having reference to the degrees of fa-
cility of respiration, very young children, and persons advanced in years,
prefer lying on the back, this posture being, as was already observed,
the most favourable to the motions of respiration. Respiration, like all
the other functions of the animal economy* with the exception of the
circulation and of the phenomena which immediately depend on it, re-
quires a kind of cultivation : it is but feebly performed at an early period
of life. It is only after a certain number of years, and when the muscles
of respiration, at first small and weak, acquire strength from the very
circumstance of being called into frequent action, that the chest dilates
'with facility, and that the lungs enjoy the full exercise of their faculties.
Until that period the enlargement of the chest and the dilatation of the
lungs took place, in an imperfect manner, the child was unable, even by
spitting, to free itself of the mucus with which its bronchias are apt to
get filled, and which render the pulmonary catarrh, called the hooping
cough, so dangerous at an- early period of life. In like manner, in an
old man, the muscles, debilitated, and returned to t,he relative weakness
of infancy, in vain strive to clear the air ceils of the mucus with which
they become obstructed in the suffocating catarrh. The mechanical
process of respiration is, therefore, equally difficult in the child, from
the weakness of the muscles which have remained in a long continued
state of inactivity; in the old man, from the debility of the same organs
and from the induration of the cartilages. Thus, at those two distant
periods of life, it is most natural to lie on one's back, but there is a suffi-
ciently remarkable difference in that respect, and which may now be in-
quired into.

In the foregoing observations, I have always spoken of the human body
as stretched on a perfectly horizontal plane. It is seldom, however, that
\ve rest on such a surface,; almost every one, and especially persons ad-
vanced in life, require that the plane should be inclined, and that the
head should be raised to a certain degree, else the brain would become
affected with a fatal congestion of blood. Children, on the other hand,

355

suffer no inconvenience from a neglect of this precaution, whether it is
that, in them the vital power has more energy, and thus balances better
the law of mechanics, by opposing more powerfully the effects of gravi-
tation, or whether it is, that in very young children, the parietes of the
arteries within the skull, have a proportionate thickness, and consequently
greater power. The extreme disproportion observable in adults, in the
thickness of the parietes, between the cerebral arteries and those of other
parts of the body, is but trifling in children; and may not this difference
of structure, which I have several times observed in the course of dissec-
tion, be considered as one of the principal causes which, in old age, bring
on apopolexy, a disease to which the child is not liable?

It is well known, that as the enlargement of the chest is produced by
the depression of the diaphragm, persons who have taken a plentiful
meal, dropsical patients, pregnant women, cannot rest, without lying on
a very inclined plane, so that the chest being considerably raised, and the
patient, as it were, seated, the weight of the abdominal viscera draws
them towards the most depending part, that their bulk may not interfere
with the depression of the diaphragm.

We might now inquire what is the posture in which the body rests with
least fatigue : this investigation, unimportant to the physician, would be
of the highest value to the arts which have for their object the imitation
of Nature. In consequence of ignorance on this subject, we often see, in
the works of several of our sculptors, figures in attitudes of repose so in-
correct and uneasy, that they could not maintain them, without consider-
able effort and fatigue.

CLXXXVII. Of the motions of progression. Of walking. Walking,
running, and leaping, are so closely connected, that it is difficult to dis-
tinguish them. There is, in fact, very little difference between walking,
in a certain manner, or running; and running is most frequently produced,
by the complicated mechanism of running and leaping. In the most na-
tural way of walking, we, in the first instance, poise the body on one
foot, then, bending the opposite foot on the leg, the latter on the thigh,
and the thigh on the pelvis, we shorten that extremity; we, at the same
time, carry it forward, extend its articulations which are bent, and when
firmly applied to the ground, we bend the body forward, and carry back
the centre of gravity in that direction; and performing the same motions
with the limb which remained behind, we measure the space the more
rapidly, cseteris paribus, as the levers of which the centre of the gravity
alternately bears, are longer. The weight of the body, compared to that
of the lower extremities, is as that of a carriage which moves, in succes-
sion, on the different spokes of its wheels.

The centre of gravity does not move along a straight line, but between
two parallels, in which space it describes oblique lines from the one pa-
rallel to the other, and forms zig zags. The oblique direction of the neck
of the thighbones, accounts for the lateral oscillations of the body, when
we walk ; the arms which move, in a different direction, from that of the
lower extremities, serve to balance us, preserve the equilibrium, and cor-
rect the staggering, which would be much greater, if the neck of the
thigh bone., instead of being oblique, had been horizontal. The impulses
communicated to the trunk, are reciprocally balanced, and the latter
moves in the diagonal of a parallelogram, whose sides are represented by
the line of these impulses. We constantly deviate from the straight line,

356

m walking, and if the sight did not enable us to see, at a distance, the ob-
ject towards which we are moving, we should go to a considerable dis-
tance from it* If you place a man, with his eyes blind-folded, in the middle
of a square field, he will, in his attempt to get out, and thinking that he
is moving in a straight line, make for one of the corners. It is, almost
always, towards the left that we deviate* the right lower extremity, which
is the stronger, inclining the body towards the opposite side* Those
who are lame depart much more from a straight line, and deviate to-
wards the side of the shorter leg. The motions which they are obliged
to use, and which render their gait so remarkable, are occasioned by the
necessity of incessant and powerful efforts, to prevent the body from giv-
ing way to its own weight^ and to the greater power of the sound extre-
mity, which inclines it towards the affected side.

The breadth of the feet, and a moderate separation of these parts, give
a much firmer support to the centre of gravity. Thus, in walking on a
moving and insecure surface, we hold apart our feet, so as to include a
greater base of sustentation. Those who have been long at sea, acquire
such a habit of holding their feet asunder, in the way they are obliged to
do during the rolling of a ship, that they cannot lose the habit, even when
on shore, and are easily recognized by their gait. A sailor is unfit for
active service* till he has acquired what is called* by sea-faring people^
a seaman's foot, that is, till he is capable of stepping firmly on the deck
of a vessel tossed by the tempest.

The gait of a woman, from her having smaller feet, is less firm ; but
ought we, from that circumstance, to infer, with the most eloquent wri-
ter of the eighteenth century, that this diminutive size of the foot, is con-
nected with the necessity of her being overtaken in flight? The concave
form of the soal of the feet, by enabling them better to adapt themselves
to the unevenness of the soil, concurs in giving a firmer footing in walk-
ing, and in other motions of progression. There is^ in walking, an in*
termediate moment, between the beginning and the end of a step, during
which the centre of gravity is in the air : this lasts from the moment whert
the centre of gravity is no longer in the foot which remains behind, till
it returns into the other foot which is carried forward.

Walking is modified, according as it takes place on an horizontal or
an inclined plane j in the latter case, we ascend, or descend, and the ex-
ertion is much more fatiguing. To explain the action of ascending, let
us suppose a man at the bottom of a flight of stairs, which he wishes to
go up $ he begins by bending the articulations of the limb which he is
desirous of carrying forward ; he raises it thus, and shortens it to advance^
and when the foot, which is in a state of semi-extension, rests on the
ground, he extends the articulations of the other extremity, carries thus
the body upward in a vertical direction, and completes this first step, by
contracting the extensors of the leg that were first in action, so that they
may bring forward and restore it to the centre of gravity to which the
posterior leg, whose foot is extended*, has given a vertical motion of ele-
vation. Hence, in ascending, the calves of the legs and knees, especially
the latter, are so much fatigued ; for, the effort with which the extensors
of the foremost leg, bring back again upon it the centre of gravity, is
tnore powerful than that by which the gemelli and the soleus impart to
it, by extending the hindmost foot, a motion of vertical elevation.

To relieve the extensors of the leg, we bend the body forward, as much

357

as possible; we lean back, on the contrary, ill descending a flight of stairs,
or a rapid slope, in order to slacken the motion, by which the body,
yielding to its own weight, falls on the leg that is carried forward,

At the moment when the centre of gravity is no longer within the base
of sustentation, all the powers unite in action, that it may fall, as little as
possible, from a vertical . direction. The glutsei steady the pelvis, and
straighten the thigh, the lumbar muscles extend the trunk on the pelvis ;
hence, in going down a slope, the loins get so much fatigued. We are
less fatigued in going down hill, when the slope is moderate, than in going
up hill | us the force of gravitation, or the weight of the body* assists con-
siderably the descending vertical motion* The motion of walking, when
we take very long steps, resembles that of going up hill, as the body being
lowered, every time the legs are much apart, requires to be elevated, at
each step, towards the foremost leg.

At every step we take, the articulation of the leg with the foot is the
principal seat of an effort, to which physiologists have not paid any at-
tention. The whole weight of the body is supported by the action of the
levatormusclesof the heel, and the astralagus supports this weight, which
varies according to the corpulence of the person, and the burthen with
which he is loaded. The weight of an adult, of common stature and of
moderate size, may be estimated at about one hundred and fifty pounds $
but which sometimes, in corpulent people, amounts to between four and
five hundred pounds. If, then, to the weight of the body, there be added
that of the burthens which it may support, it will be conceived how im-
mense the efforts must be, which are, as it was unconsciously, carried on,
in the articulation of the foot with the leg. But how numerous the re-
sources which nature has provided to overcome this great resistance;
how many the circumstances she has happily combined to accomplish
this without fatigue ! In the first place, the foot in this action, repre-
sents a lever of the second class, and this lever, it is well known, is the
most advantageous, the resistance being always nearer to the fulcrum
than the power, and the arm, by which the latter acts, consisting of the
whole length of the lever. If you attend to the mechanism of the differ-
ent parts of the skeleton, you will no where find so powerful a lever ap-
plied in so favourable a manner. The os calcis, by carrying the foot be-
yond its articulation with the leg, adds likewise to the length of the lever
by which the power acts. Its length has considerable influence on our
strength, on our power of talking, without fatigue, long walks, orengaging
in exertions requiring considerable muscular force in the lower extremi-
ties. The negroes, who excel in running, in dancing, and in all gymnas-
tic exercises, have a longer and more projecting heel than Europeans.
They dance best, whose tendo Achillis is most detached, that is to say,
projecting, and at the greatest distance from the axis of the leg; which
implies, that its lower attachment is carried back, by the prolongation of
the os calcis.

Those who have a short heel, have a long and flat foot : this conforma-
tion, which, when marked, is faulty, is not only unfavourable to beauty
of form, but is, besides, remarkably injurious to the strength of the limb,
as well as to freedom of motion. Men with flat feet, are always bad
walkers, hence, this flattened form, when very considerable, is considered
as unfitting a man for military service. Lastly, the term denoting this
physical imperfection (fiieds filats,} is accounted insulting in the French
language, as well as in several others. But let us go on with our in*

358

quiry into the advantageous disposition of the articulation of the foot
with the leg, for facility in walking, and in the different motions of pro-
gression.

We have seen that the tendons are generally inserted at a very acute
angle, into the bones on which they act; in the present instance, however,
the insertion takes place at aright angle, the common tendon of the mus-
cles of the calf of the leg joining the os calcis, at the angle most favour-
able to their freedom of action. With the exception of the muscles
which move the head and lower jaw? no others are so evidently disposed
with this purpose. Nature has not been contented with forming the foot
in such a manner as to afford the most advantageous lever, to which the
moving powers are applied, at the greatest possible distance from the
fulcrum, and at the angle most favourable to their action; she has further
increased the efficacy of this action, by adding extraordinarily to the
number of muscular fibres. There is not, in the body, a stronger mus-
cle than the soleus, whose short and oblique fibres between the two wide
aponeuroses which cover its anterior and posterior surfaces, are more
numerous than in any other muscle, as may be conceived, by consider-
ing the extensive surfaces to which they are attached. Besides, the ten-
do Achillis is kept in a due degree of straightness, by the aponeurosis of
the leg behind it.

Every thing in the powers, as well as in the levers, is formed so as to
overcome the resistance, without difficulty; that is, so as to raise the
weight of the body, by the extension of the foot, the end of which rests
on the ground in every motion of progression.

This immense power with which the muscles of the calf of the leg act
to raise the heel, and to support the whole weight of the body resting on
the astralagus, accounts for the possibility of transverse fractures of the
os calcis, and for the rupture of the tendo Achillis, notwithstanding its
great thickness ; and should lead one not to allow patients, after such ac-
cidents, to walk freely, for several months; the substance which unites
the parts being liable to rupture, as is known to have been the case in
several instances. This same arrangement of parts likewise accounts for
an accident, which physiologists have long endeavoured to explain by a
very unsatisfactory theory.

It not unfrequently happens, that the mere effort of walking occasions
a rupture of some of the fibres of the gemelh and of the soleus. in conse-
quence of which there comes on pain, attended with induration of the
muscles, and with a certain degree of ecchymosis, occasioned by the ex-
travasation of blood. Pathologists suppose these symptoms to depend on
a rupture of the plantaris muscle: this rupture, however, is hypothetical,
has never been proved by experience to exist, and its supposed symptoms
are altogether idle and fallacious.

I could, if it were not out of place, bring forward several cases of this
affection : in all the cases which have come under my own observation,
the use of the bath, of emollient and slightly narcotic poultices, but above
all, continued rest, while the symptoms lasted, have appeared to me the
most appropriate remedies.

CLXXXVIII. Of running. In running, the foot that is hindmost
being raised before that which is foremost, being firmly applied to the
ground, the centre of gravity is, for a moment, suspended, and moves iu
the air, impelled by the force of projection, the action of which princi-
pally constitutes leaping.

359

The mechanism of running is a compound of that of walking and
leaping, but resembling most the latter 5 hence some authors have defin-
ed it to consist of a succession of low leaps. The steps are not longer
than in walking, but merely succeed each other with greater velocity.
The centre of gravity is transferred, with more rapidity, from one leg to
the other, and falls are much more apt to take place. The quick repeti-
tion of the same motions, in running, requires a very lively contractility
in the muscles which move the extremities, and as the energy of this vital
property is proportioned to the extent of respiration, to the quantity of air
which the blood acquires in passing through the lungs; in running, we
pant and breathe frequently, and at short intervals, without any particu-
lar enlargement of the chest, at each act of respiration. It was necessary
that the parietes of this cavity should, in running, be remarkably fixed ;
for, it becomes the point on which those muscles are inserted which
steady the pelvis and loins, and prevent their yielding an unsteady basis
to the lower extremities. The best runners are those who have the
strongest lungs, that is, who can give to the chest the greatest degree of
permanent dilatation. In contending for the prize in running, you may
see them throw back their head and shoulders, not only to obviate the
propensity which there is in the line of the centre of gravity to fall to-
wards the anterior plane, but likewise, that the cervical column, the sca-
pulae, the clavicks, and the humerus, being fixed, may furnish a firm at-
tachment to the auxiliary muscles of respiration.

We should run with much less speed, if we applied to the ground the
whole soal of the foot; partly from the time which would be taken up in
thus applying the foot to the ground, and partly by the friction which
would necessarily take place. Hence, in running, we generally touch the
ground with the end of the foot. We run with most speed, when the
foot is in a state of extension, the leg being moved rapidly by the exten-
sors of the knee. This accounts for the tendency which there is to fall
while we run, the centre of gravity obeying the impulses which follow
each other in rapid succession, and never resting but on a basis of very
limited extent. Another reason why the slightest unevenness of the
ground is apt to occasion falls in running, is, that the rapid motion com-
municated to the body by the sudden and perpetually recurring exten-
sions of the posterior extremity, increases at every step, so that it is im-
possible to stop suddenly, and without having previously slackened one's
pace, and moderated the impulse to which the body is subjected.

As it is mostly forward that falls are apt to take place, in running we
always throw back the head, and make use of our arms to balance the
body, so that they may be in constant opposition to the legs, that is, that
the right lower extremity, for example, being carried forward, the left arm
may be balanced backward,

Few animals are better formed than man to run with speed, his lower
limbs are in ienght equal to one half of the whole length of the body, and
the muscles which move them are very powerful ; hence, savages, who
are in the constant habit of running, overtake the animals which they
make their prey ; and, even in Europe, there are professed runners who
equal in swiftness the fleetest horses. This animal, like every other swift
quadruped, would move much more slowly than man, on account of the
number of the limbs on which he rests, if he had not the power of mov-
ing them in pairs, and thus reducing his legs to two, as in what is called
full gallop.

360

CLXXXIX. Of leaping. Leaping, in man, is performed, principally
by the sudden extension of the lower limbs, whose articulations were in r.
previous state of flexion, The alternate angles of the foot, of the knee
and hip, disappear, and the extensors,, contract in almost a convulsive
manner. This straightening is not limited to the lower limbs, in violent
leaping: it, likewise, affects the vrtebral column, which acts as a bow in
unbending. Professor Barthez, who has the merit of having suggested
this explanation, which Borelli and Mayow had very imperfectly under-
stood, perhaps goes too far, in considering as imaginary, a power of re-
pulsion in the ground. This re-action, admitted by Hamberger and by
Haller, clearly operates, when we leap on an elastic floor; it enables tum-
blers to rise, without much effort, on the rope which bears them. But
though ail physiologists do not admit that, in leaping there is are-action
from the ground ; it is universally admitted, that there must be a certain
resistance, from the ground on which we tread* In fact, a moving sand,
yielding to the pressure of the body, would, by giving way to a consider-
able degree, render it impossible to leap. The instantaneous contraction
of the extensor muscles is so powerful, in extending the lower extremi-
ties, and in communicating to the body a power of projection, so as to
raise it, that frequently, during this effort, the tendons of these muscles,
or even the bones into which they are inserted, break across. It is on this
account that dancers are very apt to fracture their patella. This accident
happens, at the moment when their body, in rising from the ground, is
powerfully elevated to a certain height.

If leaping consists merely in the sudden straightening of the lower ex-
tremities, whose articulations are bent in alternate directions, it must be
more considerable, according as these are longer, more bent on one an-
other, and as the muscles which straighten them contract more powerful-
ly.—.Hence animals that move by leaps, as the hare, the squirrel, and the
jerboa, have posterior extremities of considerable length, in proportion
to their fore legs. Their different parts are, besides, capable of consi-
derable flexion. All these animals, strictly speaking, are incapable of
walking or running-, and they move by leaps or bounds succeeding each
other with different degrees of rapidity. Some, however, as the rabbit
and the hare) are capable of running, when climbing up a steep place, as
the slope, in this case, lessens the effect of the impulse communicated by
the extension of the posterior limbs; an impulse which, from the strength
and length of these extremities, throws the whole weight of the body on
the fore legs, which are weaker and shorter, with such a degree of force
that the animal is obliged to stiffen these and to keep them straightened,
and in a state of extension, to avoid striking the ground with his head,
while leaping on an horizontal plane. Frogs, but especially grasshoppers
and fleas, between whose hind extremities and the rest of the body, there
is the greatest disproportion, astonish us by the very considerable space
which they can clear at a leap; but the wonder ceases, when we consi-
der that powers communicate to the masses equal degrees of velocity,
when proportionate to one another; now, the space gone over, depend-
ing entirely on the velocity, since the body that leaps, loses, by a grada-
dion which nothing can lessen, that which it had acquired : these mo-
tions must be nearly alike in small and in large animals-

Swammerdam says, that the height to which grasshoppers rise, in

361

leaping, is to the length of their body as 200 to 1. A flea leaps still far-
ther and more swiftly*.

The larve, called the cheese maggot, forms itself into a circle, by con-
tracting, as much as possible, its abdominal muscular fibres: after hav-
ing, in this manner, brought near to each other its head and tail, it sud-
denly extends and straightens itself, and sends itself to a considerable
distance. It is by a similar mechanism, that the salmon, the trout, and
other fishes, swim against rapid currents interrupted by water-falls. They
bend their body, to a considerable degree, straighten it powerfully, and
thus overcome the obstacle which opposes their progress. I believe how-
ever, that in this particular case, the leap is not effected solely by the
straightening of the elastic curve, as is maintained by some authors, but that
it is likewise occasioned by the resistance against the water, of the tail
of the fish, which strikes it powerfully, at the moment of raising itself;
in the same manner, as in the northern seas, the enormous whale strikes,
with so sudden and violent a blow of her tail against the water, as to re-
ceive from it a fixed point, and rise to the height of fifteen or twenty feet,
as we are informed by navigators. Lobsters leap, by violently extending
their tail, an elastic and contractile arch, which they had previously kept
bent under their body.

This theory of leaping would seem to be contradicted by what is relat-
ed by Professor Dumas, of a man without thighs, and who, neverthe-
less, performed surprising feats of dexterity and agility. But in this in-
stance, might not the pelvis, the vertebral column, and especially the
lumbar portion of the latter, make up, by a greater mobility, for the
want of the longest of the three levers formed by the lower extremity.

In the act of leaping the body, which has received the impulse, may
rise in one of two ways, perpendicularly to the horizon, which constitutes
the vertical leap, or in a direction more or less oblique. The vertical
leap is always of less extent than that which takes place in an inclined
direction, and the latter is always greater, when it has been preceded
by running. In running before leaping, we have already acquired an
impulse which is added to that which the mechanism of leaping may
produce.

To convince ourselves of the reality of this additional power, let us
recollect how difficult it is to stop suddenly, in the midst of a race, if
we have not previously slacked our pace. This impulse is one of the
causes which make runners fall forward, when the slightest obstacle
meets their feet; but whatever may be the force, the direction of leap-
ing, and the powers which produce it, the body by which it is executed
must be considered as a real projectile that is impelled, by a motion
counteracted by the force of gravitation. Whatever motions we may
perform, every thing depends on the first impulse; as soon as the feet
cease to be in contact with the plane which supports them, it is no long-
er in our power to augment the force of the leap or its swiftness. In
dancing, it is impossible to excel in cutting capers, unless one is ca-

* Barthez states, in his work on mechanics, that the Arabs call this little insect the
father of leaping ; and tht't Roberval, a natural philosopher of considerable merit, had
written a work entitled de saliu pulcis. Such a subject, thought by the ignorant to sup-
ply matter only for idle and fruitles speculation, may furnish results highly interesting,
\vhen treated by an able man. In tenui labor. — Author's «/V<??e,

2Z

pable of rising to a certain height ; I have uniformly observed, that in
the most celebrated public dancers, the trunk, and especially the lower
limbs, are very muscular, the calf of the leg, the buttocks, and the bkck
indicate, by their bulk, a remarkable degree of energy in the extensors,
by whose action, leaping is chiefly effected.

A dancer who rises vertically, falls back to the ground, when the Force
of gravitation exceeds the impulse which he had received ; his fall re-
sembles that of a projectile in vertical motion ; it takes place, according
to a descending line that is perfectly similar, in direction and height to
the ascending line.

The same thing takes place in the oblique leap, except, however, that
the body, like a shell projected by the explosion of gunpowder, describes
a parabolic curve, ascending as long as the impelling power exceeds the
force of gravitation : descending, when the latter, which increases during
the progress of the leap, is equal to the force of impulse. This takes
place when the body has described a curve which represents the half of
a parabola ; from that moment, the force of gravitation goes on increas-
ing, and the body descends in a curve corresponding to the first*.

CXC. Of Swimming. Few animals have more difficulty than man, in
supporting themselves on the surface of a fluid ; yet the weight of the hu-
man body exceeds but little that of the same bulk of water : sometimes
even, when the body is loaded with much fat, its specific gravity and that
of water are the same. Hence, it is observed, that corpulent men swim
with less effort ; but the weight is not equally distributed over every
point of the supporting fluid. The head, whose relative weight is very
con sderable, is the principal difficulty in swimming, and it requires some
effort to keep it. raised, so as to allow the air to enter freely into the lungs,
through the mouth and nostrils. The upper and lower limbs act alter-
nately against the water which they displace by pressing on it. In these
various motions, fhere is a successive flexion, extension, abduction, and
adduction of the limbs ; most of the muscles of the body are in motion,
and have their fixed point of action in the chest, which swimmers keep
expanded by retaining, by a constriction of the glottis, a considerable
quantity of air within the pulmonary tissue. This continuous dilatation of
the chest is attended with this further advantage, that it renders the bo-
dy specificially lighter. The force with which the swimmer is oblig-
ed to strike the water, the rapidity with which the motions must succeed
each other, that the fluid may yield him a sufficiently fixed point of ac-
tion, accounts for the fatigue with which this exertion is attended.

Fishes are adapted by their structure, to the element in which they
live— the form of their body, bounded, every where, by salient angles,
is well calculated to separate the columns of a fluid. A bladder filled
with azote, which is expelled at pleasure, renders their specific gravity
less than that of water, according to the quantity of gas it contains ; last-
ly, their tail moved by powerful muscles, may be considered as an oar of
great strength, the motions of which impel the fish forward, while the
fins, like so many secondary oars, facilitate and direct his motions.

The air bladder of fishes gives to their back a sufficient degree of light-
ness to enable it to remain upward, else this part of the body, which is
the heaviest, would draw after it the rest, and the animal, lying on his

* In saltu ad horizontum, obliquo, motusjit perlineamparaboUcamproxime, — Borelli. op.
cit prop. 178. — Vid. Galileo on the motion of projectiles.

3B3

back, would be incapable of performing any motious of progression : this
happens when this bladder is burst or punctured. Constrictor muscles
expel the gas which it contains, and force it into the stomach, or oesopha-
gus, when the animal wishes to sink. This expulsion becomes imprac-
ticable, if the gas undergoes considerable expansion, from the application
of heat, and resists the compression that is applied to it. Hence, during
the fry-time, fishes after remaining long on the surface of the water, ex-
posed to the heat of the sun, become unable to sink, and are easily
caught*.

As the fish is entirely surrounded by a medium which presents, on
every side, an equal resistance, the velocity which he might have acquired,
by striking the fluid behind, with his tail, would be lost, from the resist-
ance of the water which he would have to displace forward, if, immedi-
ately after striking with his tail, he did not bring it back into a straight
line, so as to present to the fluid, only the inconsiderable breadth of his
body; the velocity with which he moves is, besides, very inferior to that
with which he uses his tail. This part being brought into a straight line,
the fish contracts it to the smallest dimensions, at the same time that he
brings it to the other side ; he then expands it and strikes the fluid in a
contrary direction, in a line between the two oblique impulses which both
strokes have given to it. The fish turns horizontally, and directs himself
towards the side he chooses, by striking more powerfully, or with great-
er quickness, on one side than on the other, or by striking only on one
side.

Fishes without an air bladder, are reduced to live at the bottom of the
water, unless they have a flat body and are furnished with horizontal fins,
so as to enable them to strike a considerable surface of water, in a power-
ful manner, as in the case with raysy whose wide fins are not inaptly term-
ed wings, the motion of these fishes, in water, precisely resembling that
of birds in the air, with no other difference but that of the different densi-
ty of the medium in which they move, as will be shown in treating of the
motions of progression peculiar to this class of animals.

CXCI. Of flying. ' A bird, in rising, or in moving in the air, has to
use much more force and with much greater velocity, than a fish in
swimming. He has not the power, like the latter, of placing himself in
equilibrio with the fluid in which he moves, by means of an internal or-
gan that renders his specific gravity equal to that of the medium he is in.
This medium, besides, presents less resistance to the powers which strike
it to obtain a point of support.

Though birds are unable of becoming as light as the air, it is, how-
ever, in their power to obtain a specific gravity, not much exceeding that
of the atmosphere, Nature has rendered them very light, by providing
them with very capacious lungs, capable of great dilatation, from the re-
markable-mobility of the parietes of the chest, and by extending the lungs

* The nature of the air contained in the air bag of fishes has been investigated by
PRIESTLEY and Fotrncnoz, and lately by M. 13toT. According to the accurate and ex-
tended experiments of the last named inquirer, it would appear to consist entirely of
oxygen and azote. The proportion of these gases varies according to the species and
depth at which they are caught ; that of oxygen increasing- with the depth of water
from an almost insensible quantity, until it amounts to 87 parts in a hundred of the
whole air. It would appear from the experiments of M. Biot, that this ail- is a secretions
from the sac which contains it-~Auth9r's Note.

364

into the abdomen, by means of membranous sacs, and into the skeleton,
by means of canals which establish a communication between these abdo-
minal and osseous aerial tubes and the pulmonary organ ; so that the whole
body, distended by air rarified by a considerable degree of heat, since it
is ten degrees above that of other warm-blooded animals, clothed in fea-
thers almost as light as the air itself, requires but a moderate degree of
force to support itself in that medium. On the other hand, when the
wings are expanded, they present to the fluid a very extended surface ;
the pectoral muscles which set them in motion, are besides sufficient-
ly strong to strike the air with a power, and to repeat the stroke
with a rapidity and continuousness of which no other animal would
be capable. We know how powerful* the muscles of the wings are,
even in the tame fowl, which make so very little use of them. Last-
ly, the contractility of these very powerful muscles, is greater in birds
than in any other animal, no one possesses so much strength in so small
a compass. What quadruped of the same weight as an eagle, could
strike with his foot so violent a blow as that bird, when to stun his prey
or to defend himself, he gives repealed blows with his pinion ? This mus-
cular energy is, no doubt, connected with the extensive respiratory or-
gans, with the highly stimulating qualities of a blood that is warmer,
more oxidized, more concrescible, in a word, more arterialized, than that
of any other animal.

Let us now inquire how birds, endowed with an organization so favour-
able to flying, perform that action. A bird begins by ascending into the
air, either by rising at once from the ground, or by allowing himself to
fall from a height. If, on the ground, and if his wings are too large to
be freely spread, he has a difficulty in rising ; in that case he goes to an
elevated spot and throws himself from it, that he may have sufficient
room to extend his wings and strike, in the air, the first stroke that is to
raise him. The wings expand horizontally, the humerus which forms
their principal part, standing off from the body ; they then descend ra-
pidly, and, as the air resists the sudden effort which tends to depress it,
the body of the bird is elevated by a kind of elastic re-action, correspond-
ing to the leap of man, and to the swimming of fishes; the impulse be-
ing given, the bird closes his wings, contracts his dimensions, as- much
as possible, that the impulse may be almost entirely employed in raising
his body, and may not be counteracted by the resistance of the air. The
resistance of the air, but particularly the v/eight of the bird, would soon
overcome the velocity that has been obtained, and he would drop, if, by
again striking the air, he did not again rise. If the bird strikes a second

* Birds have three pectoral muscles : the third, or lesser pectoral, is destined to
draw the Immerus, towards the body, the great pectoral, which is attached to their
enormous sternum, and alone exceeds in weight all the other muscles of the
bird together; the middle pectoral, whose tendon turns over a kind of pulley,
and is attached to the head of the humerus which it raises ; by means of this
mechanism, nature has placed an elevator muscle at the lower part of the body,
so as to increase the weight of this part of the bird, which, without this kind
of ballast, might have been upset in the air. By these and other peculiarities in
the organization of flying animals, the centre of gravity is always below the in-
sertion of the wings, and near the point on which the body is, during flight, sus-
pended. The positions, also, assumed by the head and feet, are often calculated
to facilitate flight, and give to the wings every assistance in continuing progress-
ive motion.— Author's Note.

363

time with his wings, before the impulse communicated by the tirst stroke
is over, he rises rapidly, but, on the contrary, descends, it' this motion is
delayed. If he allow himself to fall only to the height whence he began
to rise, he muy. by a continuance of equal vibrations, keep at the same
height. A bird, sometimes, ceases altogether to move his wings, closes
them against his sides and falls, with a precipitate motion, like any other
weighty body. The name of pouncing is given to the rapid descent of
predacious birds on their prey. Observe a falcon drop suddenly on a
poultry yard: if on the point of reaching the ground he perceives dan-
ger, he immediately spreads his wings, and thus saves himself from
falling ; for, whatever velocity he may have acquired in this rapid motion,
the resistance of the air always increases, as the squares of the velocity;
he then rises anew and takes to flight. This peculiar act is called
resource.

The oblique motions differ from the .vertical motion which has just
been described, in this, that the bird rises by a series of curves which
are more or less extended, as the motion is more horizontal or vertical.
In consequence of the peculiar strength of their wings, birds of prey have
a very powerful horizontal motion, so that in soaring, the curves which
they describe are so slight, that the motion seems quite horizontal.

Swimming, to many birds, is a more natural mode of progression, than
flying; these birds are very light, their body is covered with a light
down; and with feathers over which the waters glides very readily: their
body is flattened and rests on the fluid, by a broad surface. Their pelvis
is shaped like the keel of a ship ; lastly, their toes, united by webs, strike
the water with a very broad surface. This is the case with the numerous
tribes of web-footed or water-fowl*.

They who have conceived it to be possible for man to support himself
in the air, by rendering his body specifically lighter, have not consider-
ed, that it is impossible to give to the muscles which move the arms, a
sufficient degree of strength, to enable them to move the machines, which
are adapted to them; and all who have ventured to try such machines,
have suffered for their rashness.

CXCII. Of craiding. All the motions of progression, of which man
and animals are capable, may be referred to the theory of the lever of the
third kind. The body, in leaping, as in walking, may be compared to
an elastic curve, since the point of support, or fulcrum, is in the ground;
the force, the spring of power, in the extensor muscles, and the resistance
in the weight of the body. What is running, but a succession of short
leaps, and is not its mechanism intermediate between walking and leap-
ing? Are not flying and swimming real leaps, in which the body of the
animal alternately bends and unbends, having its support on media of
much less resistance than the ground, on which walking, running, and
leaping, are generally performed ? The mode of progression peculiar to
serpents and soft reptiles, furnishes an additional application of the lever
of the theory of the third kind, The snake, which moves by forming
with its body horizontal and vertical undulations, forms, in the course of

* The faculty of diving1, &.c. into a denser medium, possessed by some aquatic birds,
is exerted in the same manner as that of flying1 in the air. Swimming on the surface
of the water is performed entirely by means of the webbed feet of this class of
birds,— Authors- Note.

366

Its length, a series of curves and straight lines, in succession, from the
head towards thetail; but sometimes, likewise, from the tail towards the
head, in the serpents called amphisbcenous, in which the scales cover-
ing the belly are equally favourable to a retrogade motion, as to a motion
forward.

The crawling of serpents is facilitated by the length of their body, by
the smoothness of their scales, the immense power of their muscles, and
the flexibility of their vertebral column. The bones which form this
part of the skeleton, are articulated by arthrodia, and loosely jointed, so
that a very slight cause destroys their union: hence a blow, with a very
small stick, is capable of killing the largest serpent, if applied on the
back. The lateral inflections of this column are very considerable; the
degree of extension is limited to the spinous processes, and these are
sometimes, of considerable size, as in the rattlesnake. Hence, notwith-
standing what has been stated by several authors, and although painters
have represented serpents moving in vertical curves, they move, inmost
instances, in horizontal curves.

A serpent, to swim, is obliged to bend and unbend his body, in more
rapid succession; this swimming consists merely in crawling faster and
in moving on a less resisting plane.

The motions of reptiles, -in swimming, surpass, in strength, and velo-
city, those of reptiles which crawl on the ground, in as much as the lat-
ter yields a more fixed point than water. If the serpent is desirous of
leaping, he suddenly, and at once, brings to a straight line all his curves,
resting, at the same time, on the extremity of that which is nearest his
tail : then, as I have several times observed, fce describes the smallest
possible number of curves, bends, into three or four greater arches
than usual, but never into a single one, whatever the length of his body
may be.

Tortoises, frogs, lizards, salamanders, and all reptiles that have legs,
drag themselves along on their belly, being ill supported by their weak
limbs, which bear no proportion to the bulk of their body, and can
scarcely be said to crawl by a mechanism similar to that which has just
been explained.

Caterpillars and maggots crawl much in the same manner as serpents.
The legs of the caterpillar, too feeble to support it, or, of themselves, to
carry the body forward, are used by these creatures, to obtain a hold on
the surface on which they move, by bending in arches, mostly vertical,
the parts situated between the legs, that are in pairs, at a certain distance
from one another. The caterpillars that have a scaly covering, crawl
better, the elasticity of their scales assisting the contractile action of their
muscular fibres. Earth worms move, at times, in undulations, as the
snake, and at others, by dragging themselves like slugs. This last variety
of crawling is performed as follows : instead of forming direct curves,
the contractile fibres of the reptile, shorten themselves, from the head,
which is fixed, towards the tail which is moveable, and the animal per-
forms only slight inflexions. We may compare the mode of crawling
peculiar to some animals, to the motion by which a man lying horizon-
tally, on his belly, moves forward by drawing his whole body toward his
arms, which are in a state of extension, and with which he has a hold of
some fixed object. The motion of the snail is performed almost entire-
ly in the same manner.

The snail loaded with his shell, adheres to the surface on which he

G07

moves, by a viscid and glutinous fluid which coagulates and forfcis on his
track, a shining varnish. This creature fixes itself, likewise, on the
ground, by forming a vacuum with the part of his body on which it
crawls, which is broad, fringed, and well adapted to answer the purpose
of a cupping-glass. It is by this double resource of a viscid and glu-
tinous fluid, and of a contractile exhauster, that the snail fixes the fore
part of his body, and then draws towards this fixed part, the rest of his
body loaded with the shell. This part of the snail, by which it fastens
itself to the ground on which it crawls, bears some analogy to the tenta-
cula which assists the progression of the sepia and other cephalopodous
rnolusca.

CXCIII. Partial motions performed by the upper extremities. These
motions will furnish us additional illustrations of the elastic curve, or of
the third lever, to the theory of which, may be be referred almost all the
motions of man and of the lower animals. This idea simplifies and
facilitates, in a remarkable manner, the study of animal mechanics; it
may be considered as a general formula, by the help of which we may
obtain a solution of all the problems of this interesting part of physical
science. Its application particularly distinguishes what has just been
stated on motion, from what had been, heretofore, written on the same
subject.

The upper extremities, in man, are not employed in motions of pro-
gression, at least, not generally, except in a few instances, as for ex-
ample, when the limbs being extended and the hand having a firm hold
of a body, the action of the great pectorals draws the whole body, lying
prone on a horizontal surface, or suspended.

We experience a difficulty in climbing, because our hands alone enable
•us to grasp the body, on which this mode of progression is to be effect-
ed, while the four extremities of the quadrumana and the sharp claws of
cats, those of climbing birds, render this action easy and natural to all
these animals.

There exists so great a disproportion, in point of length and strength,
between our upper and lower extremities, that walking on all fours can
never be natural to the human species; besides, as Daubenton observed,
the situation of the foramen magnum of the occipital bone, in man, renders
this attitude exceedingly uneasy. Its situation, near the centre of the base
of the skull, and nearly horizontal, prevents the head from being- raised
sufficiently high to enable us to turn our face forward and to see before us,
and if we bring the head downward, it strikes the ground wjth its sum-
mit, or with the forehead*. But our upper or thoracic limbs, though of
no use in conveying us whither our wants require, are almost exclusively
destined to perform motions by which we act on the objects towards
which we have brought ourselves.

If we wish to push, or to draw towards us, or to propel afar a moveable
body, to compress, to elevate, or to lower it, our upper extremities are
almost exclusively engaged in this office.

In pushing, man places himself between the obstacle and the ground ;
he bends his body between these two points, by bringing all his limbs in-
to a state of flexion : he then extends them; his whole body represents a
spring which is released and recovers itself, and the two extremities of

* Dictionnaire d'Histoire Natvirelle do 1'Encyclopedie methodique. Introduction,
page 21 et suiv.

368

which, meeting two obstacles, the ground, and the body to which the im-
pulse is to be communicated, exert their action on one of the two which
is the more easily moved. The force is equal to the contraction of the
extensors, which elongate the body previously in a state of decurtation,
and advance the moveable obstacle by the whole difference, in regard to
length, of a man, whose limbs are in a state of flexion, and of the same
man while these parts are in a state of extension. It is, in the same man-
ner, and by a similar mechanism, that by pushing against the shore, with
an oar, we force a boat from it. The vertebral column represents an
elastic curve which straightens itself, between the feet which rest
against the bottom of the boat and the end of the pole or oar, pushed
against the shore, or the bottom of the water.

If, on the contrary, we wish to draw towards us a body, we seize it
with extended arms 5 we then bend them forcibly : the spring, which is
in a state of tension, shortens itself, the effort is wholly performed by
the flexors: it is less fixed, and of less duration than that of the exten-.
sors, because the axis of the bones do not correspond to one another, in
a straight line, and because the action is generally partial.

We can throw, to a distance, a projectile, the arm remaining pendu-
lous, and performing a mere oscillatory motion, or by a whirling motion
of the arm. This last action is much more powerful, because the mus-
cles which go from the trunk to the upper extremity, concur in it. In
the former, the previous oscillations give to the arm a motion which is
peculiar to it, which is added to the force of muscular contraction, and
which augments its effects.

Professor Barthez was av/are, that the motions, by which the upper
extremity stiffens itself, and assumes a state of extension to project a
moveable body, or to repel a resistance that is opposed to it, perfectly
resemble leaping, and are attended, like that action, with a sudden ex-
tension of the joints which were previously bent. In motions applied
to a resistance that cannot be overcome, the body is not repelled with
the force communicated to it in leaping, by the abrupt extension of the
lower extremities. The scapula is too moveable on the trunk, its arti-
culation with the humerus is too unsteady, and the action of this bone
is not directed, with regard to the shoulder, in a sufficiently favourable
manner, to render the impulse equally great, even though the powers
should be equal, and they are far from being so. In every repulsion, and
every attraction, whether we bring towards us an object or remove it
from us, by acting upon it, with our superior extremities, these limbs
represent an elastic arch, which is curved or straightened by the action
of its flexors or extensors, and these motions, like the greater number
of those which we have hitherto considered, present a precise applica-
tion of the levers of the third kind.

The action of seizing a body with the hand, is facilitated, 1st. by the
action of the radius on the ulna, which performs pronation and supina-
tion, motions which belong exclusively to the hands, and of which the
feet are incapable; 2dly. by the mobility of the wrist, which, properly
speaking, is capable of flexion and extension in two directions ; for, the
extension of the head does not consist in merely bringing it into a pa-
rallel line with the axis of the limb, but it is, besides, capable of turning
it round towards the back part of the fore-arm, a phenomenon not observ-
able in any other articulations ; Sdly. by the obscure motions, on one
another, of the bones of the carpus, by which the palm of the hand be-

369

comes more concave; 4thly, by the motions of opposition and circurn-

duction of the thumb and little finger ; pthly, by the great number of
the phalanges : every thing, in this part of the upper extremity, proves
the excellence of its structure, and justifies all that philosophers and
naturalists have said of its advantages.

In applying pressure, for instance, in pressing on a seal, nearly the
whole weight of the body bears on one of the upper extremities, which
is powerfully extended, the shoulder resting on the arm, so that the gle-
noid cavity of the scapula may be perpendicular to the head of the hu-
merus,

Jt would be a superfluous task to endeavour to describe all the motions
which our parts may execute ; these partial motions are explained in
anatomical works, in treating of the muscles on whose action they depend,
J shall content myself with having inquired into the principal phenomena
of animal mechanism, chiefly with a reference to the human structure.
Fuller details, on animal mechanism, would be out of place in a work like
this. They will be found in those works which treat professedly* of this*
important part of physiology, the only one in which it is possible to ob-
tain, in the investigation of its objects, that degree of mathematical cer-*
tainty, so much sought after by every man of precision and of sound
judgment,

CXCIV, Partial motions may yet farther be studied as signs ex-
pressive of ideas. They compose what is called the language of action,
and are supplemental to speech. The language of gestures, in its per-
fection, is found sufficient even to express the most subtle ideas, and the
finest feelings, in the mute scenes, known under the name of pantomimes.
The gestures, with which the man of most phlegm accompanies his dis-
course, are a language superaclded to that which he speaks: they contri-
bute to the exposition of the thought : — but what force, in the man of
passion, do they not add to his expression ? what power to his language ?
This eloquence of gesture, which was so often employed to move and
sway the assembled multitude in the public place of Rome and Athens,
was habitual to the orators of the ancient republics, and the moment when
Mark Antony uncovers and shows to the Roman people the bloody corse
of the first of the Caesars, is not the least eloquent passage of his harangue.

Thus, although the organ of voice is that which offers us the greatest
abundance of resources for the expression of our ideas, for communica-
tion with our fellow-creatures,—- though the hearing be the sense to which
we must address ourselves to produce in them distinct, varied, and lasting
impressions,— we do yet address ourselves to their touch and their sight,
when we would strongly move them, by an energetic declaration of our
desires. These three different languages are employed at once, when we
lead a man towards an object, and at the same time point it out to him,
and bid him go there : touch and gesture are then auxiliary to speech,
and testify in him who makes use of them, a strong and resolute will.
The motions of the eyes, the eye-brows, the eye-lids, the lips, and, gene-*
rally, of all parts of the face, those of the upper limbs, and of the trunk

* Consult J, A. Borelli, de matu animalium, 4to. The errors contained in this work
depend on the circumstance of the author's being more a mathematician then an ana-
tomist.

P. J. BartheZj nouvelle Jllechanigue des JHouvemens dc PHomme et des Jlnimavx.—Jlu*
Vbfe.

370

itself, serve to express our passions, as well as our ideas, are supplemen-
tal to the language of convention, and often betray it, by saying the re-
verse of what it expresses. The study of gestures, of motions, and of
attitudes, considered as signs of ideas and passions, is the department of
metaphysicians, of painters, of sculptors, and physiognomists*.

CHAPTER IX.

OF VOICE AND SPEECH,

CXCV. The voice-is an appreciable sound, resulting from the vibra-
tions which the air, expelled from the lungs, meets with, in passing
through the glottis. From this sound articulated by the motions of the
tongue, the lips, and other parts of the mouth, is produced speech, which
may be defined articulated voice.

All animals furnished with a pulmonary organ have a voice 5 for it is
sufficient, to the production of this sound, that air, collected in any re-
ceiver, be driven out in a body, with a certain force, and that it meet, on
hs passage, with elastic and vibratory parts. Fish, that have only gills,
utter no sound ; but this defect, which is certainly an impediment to the
extent and facility of their relations, is in part made up by the extreme
velocity of their progressive motion.

The instrument of voice is the larynx, a sort of cartilaginous box,
placed at the upper part of the trachea. The thin and elastic cartilages
which form its parietes are united by membranes, and moved on one an-
other by many little muscles, called laryngeal. Of these five cartilages,
three only are concerned in the production of voice, these are the aryte-
noid and the thyroid. The epiglottis is of no other use than to close, to
what we swallow, the entrance of the windpipe, whilst the cricoid, situa-
ted at the lower part of the organ, serves it for a base, on which the ary-
tenoid and the thyroid execute the motions, by which the opening of the
glottis is contracted or enlarged, for the formation of acute or grave
tones.

This slit, from ten to eleven lines long in an adult, and from two to
three wide, where the width is greatest, is the most essential part of the
larynx. It is really tke organ of voice which is gone at once, when, by
opening the trachea or the larynx below it, the air is prevented from pass-
ing through it. Speech only is lost, when the wound is above the place
of the glottis; which shows that voice and speech are two distinct phe-
nomena, one taking place in the larynx, and the other resulting from the
action of divers parts of the mouth, and especially the lipsf.

* See Condillac's Kssay on the Origin of Human Knowledge ; Button's Natural His-
tory of Man ; Winkelman's Treatise on Art ; Lavater's Essays on Physiognomy ; with
the impo.tant additions by M. Moreau (de la Sarthe) in the edition he has just pub-
lished.— Jlutnor's Note.

• See APPENDIX, Note H H.

371

Arc the different modifications of which the voice is susceptible, de-
pendent on the width or straightness of the glottis, or on the tension or
relaxation of the ligaments forming its sides ? Must we believe with Do-
dart, that the larynx is a wind instrument, or, with Ferrein, that it is a
stringed instrument ?N

It is very true that the voice becomes stronger, fuller, and passes from
the acute to the grave, as the glottis enlarges with the progress of age 5
that it remains always weaker and sharper in a woman, whose glottis is
nearly a third smaller than a man's ; — but the tension or relaxation of the
ligaments, which form the sides of the glottis, (the vocal strings of Fer-
rein) may they not enable these ligaments to execute, in a given time, vi-
brations more or less prolonged, and more or less rapid, in such a man-
ner, that if the air, expelled from the lungs by expiration, strike upon
them in the state of tension, produced by the action of the crico-aryte-
noidei postici, which carry back the arytenoidal cartilages to which the
ligaments of the glottis are attached, whilst the thyroid cartilage, to
which are attached the other extremities of the same ligaments, is carried
forward by a sort of tilting, occasioned by the muscles connecting it with
the cricoid cartilage, (crico-thyroidei)* the voice will be shrill, that is,
clear and piercing ; whereas it would be grave, if the arytenoid cartila-
ges being brought forward by the action of the crico-ayrtenoidei obliqui,
and the thyro-arytenoidei muscles, (the vocal strings being relaxed,) exe-
cuted less frequent vibrations.

It has been objected to Ferrein, that to perform the office of vibrating
strings, the ligaments of the glottis are neither dry, nor tense, nor insu-
lated, the three-fold condition required for the production of sound, in
the instruments to which this anatomist has compared the larynx $ but
for all the incompleteness of their resemblance to strings, the ligaments
of the glottis, similar to\he vibratory bodies, serving as mouth-pieces to
wind-instruments, such as the reed of the oboe, the mouth-hole of flutes,
the lips themselves in the horn, do not the less contribute to the form-
ation and varied inflexions of the vocal sound. It is the more difficult
to set aside their influence altogether, inasmuch as their state of tension
coincides always with the contraction of the glottis, and the two condi-
tions producing the same effect, it is difficult to determine if it be due to
one rather than the other, as it is impossible to decide whether it be to
the enlargement of the opening, or the relaxation of the ligaments, that
the grave tones are owing. A last reason, which, I think, should make
the larynx be considered as serving at once the purposes of a wind and a
stringed instrument, is, that the ligature or section of the recurrent nerves,
which give to its muscles their contractility, takes away the voice ; so
that there is evidently required some kind of action in the sides of the
opening.

When we wish to speak low, we contract but slightly, or not at all, the
muscles of the larynx, whose action is entirely under the direction of the
will. The column of air meeting, then, in its passage along the glottis,
only relaxed parts, and little capable of vibration, the vocal sound is no
longer produced. The permanent extinction of the voice, must depend,
in most cases, on palsy of the vocal orlaryngeal muscles.

* The arytenoid. muscle is used in the formation of acute sounds* for btiiiging togeth.
<?r the two arytenoid cartilages.—- Copland,

372

•It appears then, that, rejecting the opposite and exclusive explanations
of Ferrein and Doclart, we are to consider the larynx as an instrument
combining the advantages, and exhibiting the double mechanism of wind
and stringed instruments ; it is on this account that it surpasses all mu-
sical instruments, by the extent the perfection, and above all, by the in-
exhaustible variety of its effects. There is no one, that has heard, at a
concert, a solo on the French horn by an able performer, but has been
struck with the resemblance of the effects of this instrument, and those of
the human voice. It is because the vibrating body at the mouth piece of
the instrument, is alive : it is because the lips, like the sides of the glot-
tis, are moveable, the opening of the mouth dilates and contracts, and, at
the same time, its edges are relaxed or stiffened by the contraction of the
muscles of the lips.

The modifications of the voice, depend, not only on the varied sizes of
the opening of the glottis, and on the tension of its ligaments, but further
on the. degree of length of the trachea. The singer who runs down the
whole scale of sounds, from highest to lowest, visibly, shortens the neck
and the trachea, whilst in ascending, he stretches them out.

The force of the voice* depends on the volume of air that may be ex-
pelled from the lungs at once, and on the degree of aptness, in the pa-
rietes of the canals by which it is given out. Birds, whose body is all
aerial, have a voice very strong for their bulk. Their trachea) furnished
with a double larynx, is almostf entirely cartilaginous. It is especially so
in certain screaming birds, as the jay, and some others; whilst it is nearly
all membranous in the hedge-hog, a small quadruped, whose cries are
almost imperceptible.

The hissing of serpents, and the croaking of frogs are heard to some
distance, because these creatures can send out a large quantity of air, at
once, from their vesicular lungs, and in the last, because the vocal strings
are completely insulated from the coats of the larynx, with which in other
animals, they are continuous. }

The voice of men is strong according to the capacity of the chest. It
is always weaker after meals, when the stomach and intestines, distended
with food, push up the diaphragm and resist its descent. The voice,
formed in the passage of the air along the glottis, acquires much force
and intensity, becomes much more sonorous, by the reverberations of the
sound in the mouth and in the nasal cavities. It is weakened and disa-
greeably impaired, when a polypus of the nasal canals, or of the throat,
or the destruction of the roof of the mouth, prevents the air from passing
along the nasal canals, and their various sinuses. The voice is then said
to be nasal, though, in truth, it suffers from want of the modifications it
should receive in the cavities belonging to the nose.

CXCVI. Of speech. To whisp.tr is to articulate very weak sounds,
which, in truth, deserve not the name of voice, since they scarcely exceed
the sound, which always accompanies the passage of air in expiration.
Man only can articulate sound, and enjoys the gift of speech. The par-
ticular disposition of the mouth, of the tongue, and lips makes all pronun-
ciation impossible to quadrupeds. The monkey, in whom these parts

* Sailors, and those that live on the banks of great rivers, have commonly strong-
voices from being obliged to overpower, with the voice, the noise of the waves, which
bas constrained them to a great habitual exertion of its organs. — Authors Note.
•£ See the Memoirs of M. Ctivier on the double Jarynx, and on the voice of the birds. lb.

373

have the same conformation as in man, would speak like him, if the air
as it leaves the larynx, were not diffused into the hyo-thyroid cavities,
which are membranous in some, cartilaginous and even bony in the
howling monkey, whose cry is so hoarse and melancholy. Every time
that the animal would utter his cry, these sacs swell, then empty them-
selves, so that he is not able, at will, to supply to the different parts of
his mouth the sounds they might articulate*.

Articulated sounds are represented by letters which express their whole
force. One cannot reflect on it all, without seeing what an advance man
made towards the perfection of his nature, when he invented these signs
for the preservation and transmission of his thoughts. The vocal sounds
are expressed by the letters called vowels, that is to say, which the voice
furnishes almost completely formed, and which need, for their articula-
tion, nothing more than the more or less opening of the mouth, by the
separation of the jaws and of the lips. We pronounce, without effort,
the letters A, E, I, O, U ; they are the first the child utters; they appear,
besides, to cost him less study than the consonants. These*, which form
the most numerous class of the letters of the alphabet, serve only, as
their name indicates, to bind together their vowels. Their pronunciation
is always less natural, and consequently more difficult. Accordingly, it
is observed, that the most harmonious languages, the most grateful to
the ear, are those which use fewest consonants and most vowels. It is
in this point especially, that the Greek tongue surpasses all, ancient and
modern! ; that, of dead languages, Latin holds the second place ; and.
lastly, that Russian, Italian, and Spanish, are more agreeable in pronun-
ciation, than French, and still more than languages of Teutonic origin,
as English, German, Dutch, Swedish, Danish, Sec, Among some north-
ern nations, all articulated sounds appear to issue from the nose or the
throat, and make a disagreeable pronunciation, no doubt, because it re-
quires greater effort, and he who listens sympathizes in the difficulty
which seems to be felt by him who speaks. Would it not seem that the
inhabitants of cold countries have been led to use consonants rather than
vowels, because the pronunciation, not requiring the same opening of the
mouth, does not give the same room to the continual admission of cold
air into the lungs. The gentle pacific nature of the inhabitants of Ota-
heite, and of the other Fortunate Isles of the South Sea, is shown in the
words of their language, in which are abundance of vowels, whilst the
hard and barbarous speech of the Esquimaux of the people of Labrador,
and New Zealand, is the natural consequence of the rigour of their cli-
mate, the barrenness of their soil, and their ferocious and warlike habits.

The distinction of letters into vowels and consonants, has not been
thought sufficient : they have been further distinguished, according to the
parts which are more especially engaged in the mechanism of their pro-
nunciation. Thus we mark the labial, oral9 nasal, and lingual vowels;
and semi-vowek) M, N, R, L, which bear different names, according as
the tongue, in articulating them, strikes the roof of the mouth, the teeth,
or the lips: lastly, explosive consonants, K$ T, P, Q, G, D, B, P, and sibi-
lant^ H, X, Z, S, J, V, F, C, which are more numerous and more fre-
quently employed in languages of more difficult pronunciation. If infor-

- In the ass ah analogous structure is obsewecL

j Gratis dedit ore rotundo

..If UFO, loqid. — HOHAT.

374

tnation on this subject could be of real utility, I should explain the me-
chanism of the pronunciation of every letter of the alphabet, at the risk
of furnishing a new scene to the Bourgeois Gentilhomme.

CXCVII. Singing, stammering^ dumbness, ventriloquism. Singing is
nothing more than voice modulated, that is, running over, with varying
rapidity, the different degrees of the harmonic scale, passing from the
grave to the acute, and from the acute to the grave, with expression too
of the intermediate tones. Though, in general, our song is spoken, speech
is not necessary to it. This action of the organs of the voice requires
more efforts and motions than speech : the glottis enlarges or contracts,
the larynx rises or descends, the neck stretches out, or is drawn in : in-
spiration is accelerated, prolonged, or slackened : expiration is long, or
short and abrupt. Accordingly, all these parts are more fatigued than
by speech, and it is impossible for us to sing as long as we speak.

Whatever Rousseau may have said, in his Dictionary of Music, singing
may be regarded as the most natural expression of the emotions of the
soul, since the least civilized nations so use it, in their songs of war and
love, of joy and mourning ; and, as every affection of the mind modifies,
in some way, the voice, music, which is only imitated song, can, by the
aid of sounds, paint love or rage, sadness or joy, fear or desire, can pro-
duce the emotions of these different states, can thus sway the course of
our ideas, and direct at pleasure, the operations of the understanding, and
the acts of the will*. Of all the instruments which this art employs, the
vocal organ of man is, indisputably, the most perfect that from which
the most agreeable combinations and the most varied may be obtained.
Who is there that knows not the property of the human voice to lend it-
self to all accents, and to imitate all languages! ? I will observe, on the
occasion of song, that it is especially consecrated to the expression of
tender sentiments or movements of passion, and that it is turning it aside
from its natural or primitive destination, to employ it in situations where
no emotion can be supposed. It is this that makes the recitative of our
operas so intolerably tiresome, and throws such ludicrousness over dia-
logues where the speakers converse singing, on the most indifferent mat-
ters. Languages abounding in vowels, are thereby fitted to song, and
favour the growth of musical genius. It is perhaps their smooth and so-
norous language that has given to the music of the Italians, its superi-
ority over that of other countries^. The declamation of the ancients
was much more removed than our own, from the common tone of con-
versation, approached nearer to music, and might be noted like real
song.

The pleasantness, the precision of the voice, the extent and variety of

* See Gretry, Essai sur la Musique, &c.

j- See in the Aviceptologie Francaies, or Art c!e prende touiea so^tes d' Oiseaux, the way
in which they are drawn into snares by counterfeiting their song-.

j This pre-eminence has been strongly contested, especially in France, where to-
wards the middle of the last century, a war arose on the subject, in which her whole
literature, split into two factions, fought for the superiority of Piccini and Gluck. Out
of the heaps of writings in verse and in prose, with which. 'the contest was carried on, a
few epigrams will be remembered, the letter of Rousseau on French music, and the
little work of D'Alembert on the liberty of music. Marmontel too has made these dis-
putes the subject of an unpublished poem, under the name of Voyages de Polymnie. —
Note.

375

inflexions of which it is capable, depend on the good conformation of its
organs, on the flexibility of the glottis, the elasticity of the cartilages, the
particular disposition of the different parts of the mouth and nasal canals,
8cc. It would be enough that the two halves of the larynx, or the two
nasal canals, were unequally developed, to prevent precision and distinct-
ness of voice.

Stammering is a vice of pronunciation too well known to make it neces-
sary to define it. A tongue too bulky and thick,— a remarkable diminu-
tion of irritability, as in drunkenness, at the approach of apoplexy, and
in certain fevers of a malignant kind, — the too greatlength of the frxnum
of the tongue, — by hindering the readiness and ease of its motions, be-
come causes of stammering ; or it may be produced by the want or bad
arrangement of several teeth. The same causes, but especially the length
of the fraenum of the tongue, keep down this organ against the lower pa-
rietes of themouth, and hinder its point from striking the anterior part
of the roof of the mouth with the quick stroke, requisite for the pro-
nunciation of the letter R. The name of burr is given to this defect of
speaking.

As for dumbness^ it may be either accidental or from birth. When by
any accident, as from a gun-shot wound, a cancerous tumour which has
rendered necessary the extirpation of part of the tongue, that organ, so
far destroyed, is no longer able to apply itself to the different parts of the
parietes of the mouth, and combine its motions with those of the lips,
then the persons becomes dumb, that is to say, deprived of speech. He
has still voice, or the faculty of uttering sounds : he may even articulate,
if he supply, by mechanical means, the parts of the tongue, lips, or roof,
the want of which hinders his pronunciation.

It is not so with the dumb from birth. Frequently, all parts of the
mouth are perfect in their conformation, and yet the child cannot attain
to speech. Such is the case of a little boy of three years and a half old,
who has been brought to me, to divide his frasnum linguae. Sometimes,
however, the tongue adheres to the lower part of the mouth, because the
internal membrane of that cavity is reflected over its upper surface, long
before it reaches the middle line of the inferior. In other cases, the edges
of the tongue adhere to the gums.

Sometimes, also, the tongue is really paralytic : such was the case of
the son of Croesus, whose wonderful story is related by Herodotus*.

In the deaf and dumb from birth, the dumbness always arises from the
deafness : this, at least, is what M. Sicard has observed in the great num-
ber of pupils committed to his care, which has led him to say, that in
them, the want of speech should bear the name, not of dumbness, but of
silence. It is owing entirely to the absolute ignorance of sounds, and of
their force represented by the letters of the alphabet ; the organs of voice
show no trace of injury ; they are well fitted for fulfilling the purposes to
which they were allotted by Nature ; but they remain inactive because the
deaf child cannot be taught to use them.

It was necessary, therefore^ as the ear was closed, to address to other
senses the speech he must endeavour to imitate. His eye must be made

This is the author's solution of the story, not Herodotus's statement, who says ex-
pressly the boy was deaf. But the conjecture is ingenious, and shows a possibility in
the story, which, as Herodotus tells it, is impossible — Tram,

376

to watch the motions* of the lips and the tongue $ his hand to feel the
vibrations^ and the utterance of sound: and thence he must learn to use
his organs of speech : this has been done. What Pereira had begun, Si-
card has brought to perfection; and such command of articulate sounds
has been given to the deaf and dumb by birth, as has enabled them to
utter words and connected discourse. Even something of inflection of
strong and weaker tones has been taught them by using the arm as a re-
gulator, as pedals are employed to modify the touches of the piano-forte.

But instruction to the deaf and dumb must be given them by another
language. Written language they learn, not as a representative of speech,
but as hieroglyphic characters for ideas; and a manual language, in which
each letter is expressed by the position of the fingers or hands, is used as
a more convenient and rapid representation of that hyeroglyphic language
of written characters. It is by this that conversation with them is best
carried on ; and it is with an ease and rapidity which astonishes those,
who, for the first time, are witnesses to the use of it.

To conclude this chapter, I have still to speak of a phenomenon, well
worthy, by its singularity, of the attentiou of physiologists. It is known
under the name of -ventriloquism, because the voice weak, and little sono-
rous, appears to issue from the stomach. There was at the Palais-Roy-
al, at the Coffee-house de la Grotte, a man, who could carry on a dia-
logue so naturally, that you would think you were listening to the conver-
sation of two people, at some distance from -one another, and quite
different in voice and tone. I have observed, that he was not inspiring
while he spoke from his belly, but that less air came from his mouth and
nostrils than in his ordinary speaking. Every time that he did so, he
found a swelling in the epigastric region; sometimes he felt wind mov-
ing lower down, and could not go on long together without fatigue.

I had at first conjectured that, in this man, a great part of the air driv-
en out by expiration, did not issue from the mouth and nasal fossae, but
that, being swallowed and carried down into the stomach, it struck
against some part of the digestive tube, and produced a real echo, but
having since observed, with the greatest care, this curious phenomenon
in Mr. Fitz-James, who exhibits it in the highest perfection, I have satis-
fied myself that the name of ventriloquism no way suits it; since its
whole mechanism consists in a slow, gradual, attenuated expiration,
whether for that purpose the artist employ the power of the will upon
the muscles of the parietes of the chest, or whether he hold the epiglot-
tis slightly lowered, by means of the root of the tongue, of which he
scarcely brings the point beyond the dental arches.

I find this long expiration always preceded by a strong inspiration, by
means of which he introduces into his lungs a large quantity of air, of
which he afterwards husbands the use. Accordingly, repletion of the
stomach is a great hindrance to the action of Mr. Fitz-James, by pre-
venting the descent of the diaphragm which the chest would require, to
dilate itself for the full quantity of air the lungs should receive.

By accelerating or retarding expiration, he can imitate different
voices, make it seem that the speakers, in a dialogue, which he carries on

* It is known, that old men, grown deaf; fix their attention very closely on the mo-
tions of the lips, as well as on the varying1 expressions of the i'ace, to see the words as
well as thoughts of those who are speaking. — Author's JVbte

377
i

by himself, stand at different distances, and produce illusion the more
complete, the more perfect is his talent. No one equals Mr, Fitz-Jame»
in the art of deceiving, in this respect, the most wary and suspicious ob-
server.

He can set his organ to five or six different tones, pass rapidly from
one to the other, as he does when he represents a very eager discus-
sion, in a popular society, imitate the sound of a bell, and carry on,
singly, a conversation, in which one might think that several per-
sons of different ages and sexes were taking parts. But what completes
the illusion} and especially distinguishes the art of the ventriloquist from
that of the mimic, who can only counterfeit, consists in the power of so
modulating his voice, that one is deceived as to the distance of the speak-
er,in such sort, that one voice comes from the street, another, from a
neighbouring apartment^ that, from one that had clambered up the roof
of the house. Sec, It is easy to discern the value of such a talent in the
days of oracles*

SECOND CLASS,

FUNCTIONS

SUBSERVIENT TO THE PRESERVATION OF THE
SPECIES.

381

CHAPTER X.

OF GENERATION.

CXCVIII. Difference of the sexes. The functions treated of in this
chapter are not necessary to the life of the individual, but, without them,
the human species would soon perish, for want of the power of reproduc-
tion : these functions, destined to preserve the species, are entrusted to
two kinds of organs, belonging to the two sexes, of which they constitute
the principal, though not the only difference.

Woman, in fact, does not differ from man, in her genital organs mere-
ly, but, likewise, in her lower stature, in the delicacy of her organization,
in the predominance of the lymphatic and cellular systems, which softens
down the projections of the muscles, and gives to all her limbs those
rounded and graceful forms, of which we see, in the Venus of Medicis,
the inimitable model. In woman, sensibility is also more exquisite;
and with less strength, her mobility is greater. The female skeleton
even is easily distinguished from that of the male, by striking differences.
The asperities of the bones are less prominent ; the clavicle is less curv-
ed, the chest shorter, but more expanded, the sternum shorter, but wider;
the pelvis more capacious, the thigh bones more oblique*, Sec. In a dis-
sertation on physical beauty, read by Camper to the Academy of Design,
at Amsterdam, this celebrated physiologist showed, that, in tracing the
forms of the male and female body within two elliptical areas, of equal
size in both, the female pelvis would extend beyond the ellipsis, and the
shoulders be within^ while in man, the shoulders would reach beyond
their ellipsis, and the pelvis be contained within its limits.

The general characters of the sexes are so marked, that it would be
possible to distinguish a male, merely by seeing a part of his body naked,
even though this part should not be covered with hairs, and should have
none of the principal attributes of virility. Should this difference of or-
ganization and character be abscribed to influence of the sexual organs
upon the rest of the body ? Does the uterus impress on the sex all its
characteristic modifications, and is it just to say with Vanhelmont : Profi-
ler solum uterum mulier est^ id quod est ; the uterus alone makes woman
what she is. Though this viscus, very evidently, re-acts on the whole
system of the female, and seems to draw under its controul nearly the
whole of the actions and affections of woman, I am, nevertheless, of opi-
nion, that it is far from being the only cause of her distinguishing cha-
racteristics, since these may be recognized from the earliest period of
life, when the uterine system is far from having attained its full activity.
A very singular fact, recorded by Professor Cailliot, in the second volume
of the Memoirs of the Medical Society of Paris, proves better than all

* Compare the beautiful plates of the male and female skeleton by Albinus anc!
Soemmering, '

38%

the reasoning In the world, how much the character of the sex is fade*
pendent of the influence of the uterus. A female was born and grew up
with all the external characteristics of her sex. At the age of twenty-
one, she wished to yield to her desires, but found it impracticable ; there
was nothing beyond the vulva, in other respeqts well formed. A small
canal, between two or three lines in diameter, occupied the place of the
vagina, and terminated in a cul de sac, and was about an inch in depth.
The most accurate examinations, by introducing a sound into the blad-
der, and the finger up the rectum, discovered nothing like the uterus.
With the finger in the rectum, the convexity of the sound in the bladder,
could be distinctly felt, so that it was evident, that, between the lower
part of the bladder and the anterior part of the rectum, there lay no o*-
gan corresponding to the uterus. The young woman, had never been
subject to the periodical evacuation which accompanies or precedes the
time of puberty. No haemorrhage supplied the place of this excretion.
She experienced none of the indispositions that are occasioned by the
absence of menstruation ; she enjoyed, on the contrary, the most perfect
health; she was deficient in none of the other characteristics of her sex,
only that her breasts were small. At the age of twenty-six or twenty-
seven, she became subject to a pretty frequent evacuation of bloody urine.
May not this affection, which recurred at irregular periods, be consider-
ed as a means by which nature supplied the deficiency of the menstrual
evacuation ? The bladder, in that case, would fulfil the office of the Ute<-
rus, and its capillary vessels must have been considerably evolved.

The reproduction of the species is, in woman, the most important ob«
ject of life 5 it is almost the only destination to which Nature has called
her, and the only duty she has to fulfil in human society. Wherever the
earth is fruitful, and furnishes man with abundant means of providing
for his wants, he dispenses with the services of woman, in obtaining from
it means of subsistence, he releases her from the burthen of social obliga-
lions. The Asiatic expects from the women he maintains in his seraglio,
in a state of inactivity, nothing but pleasures and children to perpetuate
his race. The women of Otaheite have no employment but pleasure and
the duties of mothers. Among some of the savage tribes of America,
man, abusing the right of power, tyrannizes, it is true, over woman, and
reserving to himself all the advantages of social life, makes her bear all
its weight; but this exception does not invalidate the general law de-
duced from observation of all nations. Whatever withdraws woman
from this primitive destination ; whatever diverts her from this end is
to her injury ; it is, the scope of all her actions and habits, every thing,
in her physical organization? has evident reference to it. Of all the pas-
sions, in woman, love has the greatest sway; it has even been said
to be her only passion. It is true* that all the others are modified by it,
and receive from it a peculiar cast, which distinguishes them from those
of man*.

We will enter no further into the examination of the general differences
which characterize the two sexes ; no one has entered more deeply into

*' Fontenelle used to say of the devotion of some women : One may see that love has
been here. It has been said in speaking of St. Theresa : To love God is still to love.
Thomas maintains that, ivith women, a man is more than a nation. Love is but an episode
in the life of man ; it is the whole history of the life of -woman. (Madame DE S

this subject, or has treated it in a more interesting manner, than Mi
Roussel, in an excellent work entitled, Syateme physique ct morale de la
femme.

XCIX. Htrmaphrodism. Hermaphrodism9 or the union of the two
sexes in the same individual, is impossible in man, and in the numerous
class of red-blooded animals* There is, on record, no well authenticated
case of such a combination^ and all the hermaphrodites, that have been
hitherto met with, were beings imperfectly formed ; in whom imperfect
male organs, or female organs unnaturally enlarged, rendered the sex du-
bious. None was ever found that had the power, by itself, of begetting
a similar being to itself: the greater number were incapable of reproduc-
tion : the imperfection, or the faulty conformation of their organs, con-
demned them to barrenness. Such was the case with the hermaphrodite
mentioned by Petit Namur, in the Memoirs of the Academy of Sciences;
•with that one whose case is related by Maret, in the Memoirs of the Aca-
demy of Dijon, and with all those to be found in the records of the Me-
dical Society, which contain the greatest number of facts of this kind.

But though, in man^ and in all beings that most resemble him, in their
Organization, complete hermaphrodism has never been met with, it is a
frequent occurrence among the white-blooded animals, and especially
among the plants that occupy the lowest part of the scale of organized
beings. The same is observed in polypi, in several kinds of worms, in
oysters, and snails. The latter present a singular variety of hemaphro-
dism, in this, that the male and female organs being combined in the
same individual, it is still, singly, not capable of generation, but is obliged
to copulate with another being likewise an hermaphrodite, so as to re-
ceive, from friction, and other means of irritation, the excitement of the
act of reproduction,

In the immense tribe of monoecious plants, the male and female organs
are combined on one stalk, and even sometimes within the same flower*
A number of stamina surround one or more pistils, and shed on the stig-
ma their fertilizing dust or pollen, which is conveyed, along the canal of
the style, into the ovary, there to impregnate the seeds by means of which
the species are perpetuated, The same vegetable species containing, some-
times, male and female individuals, the sexes may be at considerable dis-
tances from one another; the seminal dust is$ in that case, conveyed by
the air from the male to the female. This is the case with the palm trees
on which Gleditsch made his tirst observations on the generation of plants;
hemp, spinage, mercurialis, &c,

CC. It is a distinction of the human species that* in them, the func-
tions of generation are not under the influence of the seasons. The lower
animals, on the contrary, draw together, and pair stated periods of the
year, and seem afterwards to forget the enjoyments of love, that they may
attend to their other necessities. Thus, wolves and foxes copulate in the
middle of winter; deer, in autumn, most birds in spring. Man alone
seeks his partner at all seasons of the yearj and impregnates her under all
latitudes and in all temperatures. This privilege is not so much the
consequence of his peculiar constitution, as a result which he derives
from his industry) protected by the shelters which he constructs against
the inclemency of the seasons, and the variations of the atmosphere ;
always capable of gratifying his physical wants by help of the stores
which his foresight has led him to collect, he can at all times indulge in
the enjoyments of love. The domestic animals which we have, in great;

884

measure, removed from the influence of external causes^ bring forth al-
most indiscriminately, at all seasons of the year. To prove still farther^
that is from counteracting, by the resources of his industry* the influence
of nature^ that man has succeeded in resisting; the influence of the sea-
sons, in the reproduction of his species, 1 may observe, that this effect
of temperature is more absolute, the farther the species is from man;
hence the spawn of fishes and frogs is productive sooner or later, accor-*
ding to the earliness or lateness of the season, and thus a great number
of insects depend on the heat of the weather for their powers of repro-
duction, and for their existence.

CCI. Of the organs of generation in man. Aristotle, Galen, and their
verbose commentators, have expressed the analogy which subsists be-
tween the organs of generation, in the two sexes, by saying that f.hey
differ only in their position, being external in man, and internal in woman.
There is, in fact, a considerable resemblance between the ovaria and the
testicles, the fallopian tubes and the vasa deferentia, the uterus and the
vesiculoe seminalis, the vagina, the external organs of generation in wo-
men, and the male penis. The former secrete the seminal fluid, and fur-
nish in man or in women, a matter essential to generation (ovaria and
testicles.) The fallopian tubes, like the vasa deferentia, convey this fluid
into recepticies where it has to remain for some time (uterus and vesiculse
seminales.) These contractile cavities, which serve as reservoirs to the
semen, or its product, part with these substances, when they have re-
mained within them a sufficient length of time ; lastly, the vagina and
penis serve to expel them. However striking such analogies may be, we
are not justified in inferring a perfect resemblance between the organs of
generation in the two sexes* Each of them fulfils, in ,the act of repro-
duction, functions perfectly distinct, though of reciprocal necessity.

The prolific fluid is secreted by the testicles : these organs are two in
number, covered by several coats, one of -which, covered by the skin, and
known under the name of scrotum) resembles a bag containing both these
organs : it contracts on the application of cold, is relaxed by heat, and
possesses a degree of contractility more evident than the other parts of
the cutaneous tissue. The dartos forms a second cellular envelope com-
mon to each testicle* The tunica vaginalis, a serous membrane, affords
an immediate covering to them, and reflecting itself over the surface, is
disposed with regard to them, as the peritoneum with regard to the abdo-
minal viscera, that is, it does not contain them within its cavity. Lastly,
the testicles are covered by a fibrous, white* thick, and very consistent
membrane : it is termed tunica albuginea, from the inner surface of which
there arise a considerable number of membranous lamina, which, crossing
one another, within its cavity, form cells containing a yellowish vascular
substance. This substance contained within the tunica albuginea, has so
little consistence, that it would very soon be dissolved, if the testicle were
stripped of its outer covering. It is formed by the seminiferous tubes,
which are small capillary vessels extremely tortuous and coiled on them-
selves, arising, probably, from the extremities of the spermatic arteries,
all directed towards the upper part of the oval formed by the testicles,
joining in this place, and forming about ten or twelve tubes, which unite
into a cord situated within the tunica albuginea* called the corjius High-
morianum. The ten or twelve ducts which unite into a fasciculus, and
form this cord, pass through the membrane within which they are con-
tained, unite into a single canal which is convoluted, and form? a sub-

stance called the epididymis. This canal, formed by the union of the
ducts of the corpus Highmorianum, at first convoluted on itself, becomes
less and less tortuous, as it approaches the lower extremity of the testi-
cle : there it bends back and ascends under the name of vas deferens,
along the spermatic cord, as far as the inguinal ring, by which it enters
the abdominal cavity. The vasa deferentia, though of the size of a quill,
have, nevertheless, a very small cavity, and it is not easy to say why a
capillary tube should have such thick pareties, and nearly as hard as
cartilage.

The semen, secreted by the testicles, is formed from the blood conveyed
to them by the spermatic arteries, long, slender, and very tortuous ves-
sels, arising from the aorta, at a very acute angle. This fluid is filtered
through the seminiferous tubes, passes into those of the corpus High-
morianum, and thence into the vasa deferentia, which, after they have en-
tered the abdomen, terminate into the vesicuse seminales, and deposit into
them the spermatic fluid. The delicacy of the organization of the testicle,
the delicacy of the vessels along which the semen is conveyed, account
for its tendency to congestion, and for the difficulty with which a resolu-
tion of this affection is obtained.

The spermatic fluid passes, from the vasa deferentia, into the vesicular
seminales, notwithstanding the retrograde direction of their course. The
cavities serving as receptacles to the semen, resemble, in this respect, the
gall bladder. Notwithstanding the unfavourable direction in which the
ducts of the liver and of the testicles join in their respective receptacles,
they nevertheless convey the fluids into the latter ; the bile, because the
ductus choledocus is pressed by the coats of the duodenum, contracted
on itself when empty 5 the semen, because the duct along which it is con-
veyed, penetrating through the prostate gland, and opening into the ure-
thra, by a very narrow orifice, this fluid flows back more readily into the
vesiculae seminales, than from the vas deferens into the ejaculatory duct.

The vesiculae seminales form two membranous receptacles of different
capacity, in different individuals, larger in young people and adults, than
in children and old people. Their cavity is divided into a number of
cells ; they are lined with a mucous membrane, which secretes, in con-
siderable quantity, a viscid humour that mingles with the semen, in-
creases its quantity and serves as a vehicle to it. The situation of the
vesiculae seminales, between the rectum, the levatores ani, and the pos-
terior part of the bladder, promotes the excretion of their contents,
(which is chiefly brought about by the contraction of their parietes) by the
compression of the levatores ani, which are in a state of convulsion at the
moment of emission. Animals that are not provided with these seminal
receptacles, remain a considerable time in a state of copulation, the pro-
lific fluid necesfary to impregnation having to be secreted during the
time that the copulation lasts, and flowing in drops.

The ducts formed by the union of the vesiculae seminales with the vasa
deferentia, pass through the prostate gland, and open, by separate ori-
fices, into the urethra, at the bottom of a lacuna, near the verumoritanum.
The glandular body in which they are inclosed, and which contains both
the neck of the bladder and the beginning of the urethra, does not exist
n women. The mucous and whitish fluid, secreted by the prostate, is
conveyed by ten or twelve orifices into the urethra. This prostatic fluid
mingles with the semen, adds to its quantity, is perhaps emitted first, in
order to lubricate the internal surface of the canal, and prepare it for the

3 C

386

passage of the seminal fluid, by rendering the internal surface of the
urethra more slippery. The use of the urethra is, not only to convey
the semen out of the body, but likewise to serve in the excretion of the
urine, and to form a part of the penis. The latter destined to convey
the prolific fluid into the female organs of generation, must be in a state
of erection to perform this function completely. Erection being a phe-
nomenon of structure, that of the penis will be considered, after the de-
scription of the female organs of generation*.

CCII. Of the female organs of generation. I shall not adopt the ana-
tomical arrangement generally followed in this description, but classing
in three divisions, the different parts which, in women^re subservient to
the genital function, I shall speak first of the ovaria and fallopian tubes,
then of the uterus, and in the last place of the vagina and external parts.

The ovaria, situated in the female pelvis, connected to the uterus by a
ligament, receive the vessels and nerves which, in women, are sent to the
testicles ; they resemble in form the latter, but are somewhat smaller.
Do the ovaria secrete a fluid, which, by mixing with the male semen,
produces the new being, or is there detached from them, at the moment
of conception, an ovum which the semen vivifies? Whatever opinion
is adopted, one is compelled to admit, that the ovaria prepare a substance
essential to generation, since females, in whom these parts have been ex-
tirpated, are rendered barren.

It is likewise, unquestionably along these membranous tubes, called
fallopian, that this substance, whatever it may be, furnished by the ovaria,
passes into the uterus, into which one of their extremities opens : while
the other extremity, broad and fringed, lies loose in the cavity of the pel-
vis, supported by a small duplicature of the peritoneum, but undergoes
a state of erection, and applies itself to the ovarium, during the act of
coition, and forms a continuous canal between that organ and the cavity
of the uterus. The external orifice of the fallopian tube, called corpus
fimbriatum, has been found grasping thus the ovarium, in females opened
immediately after coition. It may happen, from a malformation of the
parts, that the fallopian tube may not be able to apply itself to the ova-
rium. I dissected at the Hospital de la Charite, the body of a woman
who had been barren ; and found the corpora fimbriata, or the expanded
termination of the fallopian tubes, adhering to the lateral parieties of the
pelvis, so that it was impossible they should perform the motions re-
quired for impregnation.

The uterus, lying in the pelvis, between the rectum and the bladder, is
a hollow viscus, in which the foetus grows till the period of birth. Its
internal part has been found separated into two cavities, opening, in some
cases, in the same vagina, and at others, terminating in a vagina that
•was double, only in the immediate vicinity of the uterus. Valisnieri
mentions the case of a woman who had a double uterus, the one opening
in the vagina, and the other communicating with the rectum. Though
the muscularity of the pareties of the uterus becomes manifest, in pro-
portion as this organ enlarges, during the progress of pregnancy, this
hollow muscle may be said to differ from other muscular organs, by the
arrangement of its fibres, which it is difficult to discover while its cavity
Is empty, and which it is even impossible completely to unravel, while it
contains the foetus ; its most remarkable distinguishing character, is its

See APPENDIX, Note 1 1.

387

singular property of dilating and stretching itself, and, at the same time,
of gaining in thickness instead of becoming thinner.

The vagina is remarkable, only by the soft, wrinkled, and easily dila-
ted structure of its parietes. The upper extremity of this oblique canal,
which is directed upward and backward, embraces the cervix of the ute-
rus, while its lower orifice is surrounded by a spongy body, whose cells
fill with blood and expel it, like the corpora cavernosa of the penis and
clitoris. It is called plexus retiforme ; its turgesccuce, during erection,
contracts the orifice of the vagina ; the contraction of the constrictor
muscles, which answers the purpose of the accelerator urinae in man, and
which lies over this plexus retiforme, surrounds, like it, the entrance of
the vagina, and may, in the same manner, contract the orifice of this canal.

Besides, this external orifice is furnished, in women who have had no
connexion with men, with a membranous fold, varying in breadth, gene-
rally semicircular, and called hymen. Its existence is considered by
many, as the most certain sign of virginity. But all the marks by which
it has been attempted to obtain a certainty of the presence of virginity
are very equivocal*. The relaxed state of the parts, from a great quan-
tity of mucus, in a woman subject to the fluor albus; or from the blood
of the menstrual discharge, may make the hymen yield and not rupture,
so that a woman might seem a virgin without being such ; while another
•woman who has not lost her virginity, might, from illness, have her hy-
men destroyed. There are, in the last place, persons in whom the hymen
is so indistinct, that several anatomists have doubted its existence!.

The other external parts of generation, which are easily discovered,
without the aid of dissection, cannot be considered as merely ornamen-
tal ; all are, as will be shown presently, of real utility. The folds of skin
which form the labia and the nymphae, yield during the delivery of the
fo3tus. These duplicatures not only unfold themselves, but likewise un-
dergo a degree of extension, their tissue being moister, softer, and more
extensible than that of the skin. The mons veneris, the hairs which
cover it, the clitoris, which resembles an imperfect penis, seem merely
organs of voluptuousness; but is not pleasure itself an element in the
act by which the human species is reproduced}: ?

CCIII. Of conception. When a chemical, mechanical, or mental irri-
tation excites the action of the genital organs, the penis elongates itself,
becomes turgid and stiff, from the accumulation of blood within the cells
of the corpus cavernosum, and within those of the corpus spongiosumof
the urethra§. The turgescence of these two parts of the penis should be
simultaneous, to render the erection complete. It has been thought that
this phenomenon might be accounted for, by the compression of the
pudic veins, which are situated between the symphysis pubis and the
root of the penis, which, as long as the erection lasts, is compressed
against the bone by the erector muscles. But far from elevating the penis,
the muscles of the perineum, especially the ischio cavernous (erectores

* Attamen prima venusdebet^esse cruenta." — Hatter.

•j- It nevertheless always exists, but its size is very various. In some females it coi*
pletely closes the vagina, and, in this case, it causes retention of the menses. In other
cases, the occlusion not being1 complete, foccundation may take place by menns of a
very small opening-, and without the introduction of the penis — Copland.

* See APPENDIX, Note 1 1.

§ «• Penis adest, ita consmctus, ut sthnulo corporeo sive mentali irritatus, turgeat et
obrigescat, seque erigat, postea detumescat, et collabatur."— Crevt.

tend to depress It. The blood -which distends the corpora
flosa of the penis, and the corpus spongiosum of the urethra and glans,
which is itself the expanded extremity of the urethra, does not stagnate in
their cells, only there is a greater quantity of blood in them than usual; the
irritation increasing, in a remarkable manner, the action of the arteries.
Erection, always proportioned to the degree of the stimulus, ceases,
when the cause of irritation no longer acts on the penis; in the same
manner that an inflammatory tumour is discussed, when the cause is re-
moved*. In this voluptuous dilatation, the urethra is brought into a state
of erection, being put on the stretch by the penis which is elongated, its
curves are straightened, the irritation is propagated from the external to
the internal parts, to the vesiculse seminales and the testicles. These
swell, and their secretion is increased, as they receive a gentle degree of
motion from the action of the scrotum, which becomes wrinkled and
draws them up towards the abdomen, and by the action of the cremaster
muscle, whose expansion formsbetween the tunica vaginalis and the dar-
tos, what has been improperly called the tunica erythroidea ; they empty
themselvess with the greater ease along the vasa deferentia, which de-
crease in length, as the testicles rise, and which participate in the con-
cussion affecting these organs.

The concussions of the cremaster on the testicle, or on the vassa defe-
rentia, promote, in so important a manner, the secretion and excretion of
the semen, that this little muscle is fonnd in animals whose testicles never
leave the abdomen, but remain within that cavity on the sides of the lum-
bar region, as was observed by Hunter in the hedge-hog and the ram.
This fact of comparative anatomy shows that the cremaster is of use, not
merely in suspending the testicles, as its name indicates, since in the ani-
mals above-mentioned they return into the abdomen towards the organ
on which they are to act.

When irritation is carried to a certain length, it acts on the vesicu-
lae seminales, and these on the fluid which fills their cavity, and they
expel it, by the spasmodic contraction of their membranous parietes, as-
sisted, in this excretion, by the levatores ani. (CCI.) The prostrate
gland and the mucus glands of the urethra furnish a viscid substance, cal-
culated to promote the evacuation of the seminal fluid, which is emitted
in jets, more or less rapid.

CCIV. The human semen is never emitted in a state of purity, that
is, such as it is prepared by the testicles : it is even conjectured, that the
mucous fluid of the vesiculae seminales forms the greatest part of it. It
is this mucous which eunuchs emit in considerable quantity. The fluid
secreted by the prostrate gland and by the mucus glands of the urethra,
affect it, likewise, by uniting with it.

On being received into a vessel, it exhales a peculiar smell like that of
the pollen of a great number of plants, for example, of the chesnnt-tree.
It consists of two parts, the one thick and in clots, while the other is vis-
cid, white, and more fluid. The proportion of the fluid to the semi-con-
crete part is greater, in proportion as the person is weaker, and as the
emission of semen is more frequently repeated. It soon liquifies, by
losing part of its weight, which always exceeds that of water in which it

* The animal heat is somewhat augmented, during erection, as in inflammation. The
temperature of the blossoms of tire arum rises several degrees above that of the atmos-
phere, at the moment of impregnation. —

'389

becomes soluble, though it \vas not so at first. On being analyzed by M.
Vauquelin, it was found to contain of water 90 centimes — of animal mu-
lage 6— phosphate of lime 3 — soda 1. It is in consequence of this last
alkali, that it is enabled to turn syrup of violets to a green colour, The
animal mucilage is not pure albumine, but rather a gelatinous mucus, on
which the qualities of the semen appear particularly to depend, such as
its insolubility in water, its odour, and spontaneous liquefaction.

On being examined with the microscope, the semen is seen to contain
small animalcules, with a rounded head, a tapering tail, and moving with
rapidity. Is the liquefaction of the glutinous and viscid parts of the
semen, owing to the motion of these creatures ? These microscope ani-
malcules are to be detected in the semen only at the period of puberty*.
It has been thought that they shunned the light: authors have even gone
the length of describing their ways and then' diseases. The imagination
has had much to do with all that naturalists have fancied they saw in
these creatures, which they made subservient to theirexplanationsof the
mechanism of reproduction* However, it must be confessed, that in all
the animal fluids, and in the juices of many plants, a certain number of
these animalcules may be detected by means of the microscope.

A spasmodic contraction affects, during the expulsion of the semen, not
only the organs of generation, but the whole body participates in the con-
vulsive state, and the moment of emission is accompanied by a commotion
of all its parts ; so that it should seem, says Bordeu, that in that instant,
Nature forgot every other function, and was solely engaged in collecting
her strength and directing it to one organ. This general spasm, this, as
it were, epileptic convulsion, is followed by universal depression ; this
physical lassitude is attended with a sensation of sadness, which is not
without enjoyment. Does this peculiar sensation, which, according to
Lucretius, mingles grief with the most lively enjoyment of which we are
capable, depend on the fatigue of the organs, or, in truth, as some meta-
physicians have imagined, on the confused and distant notion that occurs
to the soul of its own dissolution ?

^ The penis does not enter the uterus, though the semen does. The os
tincse offers too small a slit, and its thick edges are besides in contact. It
would be difficult to conceive that this straight passage should admit
even the animal fluid, if it were not known that in the moment of copu-
lation, the uterus, from, irritation, draws together, and inhales, by real
suction, the semen which it craves. Plato compared this organ to an ani-

* The author states in his last edition, on the authority of one observer only, that ani-
malcule are not found in the semen of individuals affected with syphilis. He also ob-
serves, that he has frequently had reason in the course of his practice to impute sterility
in the male to the existence of the lues venerea ; this latter circumstance, however, may
be otherwise explained than by supposing that the seminal animalculae are not genera-
ted during- this disease. Indeed the existence of those animalcule is a matter of much
doubt. We believe that what has been usually supposed to be such, are nothing more
than the minute portions of some one of the very different secretions, mentioned above,
as constituting the seminal fluid, in the act of move intimate mechanical mixture, or of
union, with those of the others. The appearance of animalcules may be also exhibited
by the secretion of a single organ or part ; for, as all secreted fluids are not actually ho-
mogeneous, their minute particles, which differ in colour, consistence, &c. from the
more abundant and more aqueous portion, would very probably give rise to the decep-
tion in question. — Copland.

The recent researches of Prevost and Dundas have incontestibly established the fact
of the existence of these aTumalculse.—Go

396

inal living within another animal, controlling all the actions of the living
economy, burning to sate itself with the liquor of the male, and digesting
it to form a new individual.

The great thickness of the cervix of the uterus has given room for
reasonable doubt, if its orifice could dilate sufficiently to admit a fluid of
the consistency of semen, Some, therefore, have thought that it was not
this fluid itself that penetrated into the cavity of the uterus, but the sub-
tlest of its parts, the most spiritualized, a prolific vapour, to which they
have given the name of aura seminalis ; but, besides that the semen has
been found in the uterus, in animals opened immediately after copulation,
Spallanzani, in his experiments on the fecundation of frogs, of salaman-
ders, and toads, perceived that, to enable the eggs to produce, it was not
enough to expose them to the vapour which rises from the seminal fluid
of the male : and that nothing was effected, unless the fluid semen actually
touched them, though in ever so small a quantity.

It has been said, that the uterus dilates to receive the semen, constricts
itself to retain it, and that this spasmodic contraction of the uterus, felt,
as Galen assures us, by women, who preserve enough sang-froid to make
observations in that situation, was the most undoubted sign that could be
had of the success of the copulation. It is, no doubt, to ensure this re-
tention, that it is customary to throw cold water on the females of some
domestic animals, when they go too eagerly to the male. The spasm of
the skin, occasioned by the cold striking it, affects the uterus, and hin-
ders the flowing back of the semen which has been thrown into its ca-
vity.

It has also seemed, that women conceive more easily, for a little time
after menstruation ; when the mouth of the uterus is less exactly closed
than usual.

The seminal fluid, thrown into the cavity of the uterus, passes along
the fallopian tubes to the ovaria. It does not diffuse itself in the cavity
of the abdomen, because the membranous duct seizes the ovarium, which
corresponds to it, grasps it closely, and establishes an uninterrupted canal,
from this organ to the uterus. The ovarium, bedewed by the semen, ir-
ritated by its contact, lets a fluid escape, or perhaps a little ovum, which
passes into the uterus, the same way that the semen reached itself*. All

* The account here given of the fecundation of the ovum, seems to us exceedingly
erroneous, and as this is a point of some interest, we will not too hastily dismiss it.

It is our intention, first, to show that the semen does not enter the cavity of the ute-
rus, much less that it reaches the ovary. Those who differ from us on this subject, have
mostly insisted that the semen is thrown into the uterus, by injection from the penis.
True it is, that some other modes have been suggested, but they are really so ridiculous,
as to be wholly unworthy of criticism.

That the male organ is endowed with a considerable projectile power, cannot be de-
nied. It is very conspicuously evinced, by the impetus with which the urine is dis-
charged.

But admitting, that by an unusually vigorous impulse, it were projected as far as the
uterus, how could it enter into the cavity of that viscus ? Let it be recollected that the
os tincae, at least, in the virgin state, is nearly as small as the opening of the urethra in
the male, and is not placed in the immediate axis of the vagina, but is inclined more or
less to the one or the other side, or towards the sacrum. The apertures of the two
organs, therefore, are not in opposition. But this is not all. The os tineas is for the
most part filled with a thick glutinous matter, capable of considerable resistance. Where
it is wanting, as is generally the case in the virgin uterus, the hard, unyielding lips of
the tinea are so closely approximated as to be nearly closed.

Nor arc these the only obstacles to the passage of the semen. The canal leading-

391

that remains to be said, concerning the mechanism of generation, must
not be delivered as real but merely as probable, such is is the darkness
with which Nature has chosen to envelope this great mystery of the living
economy*.

through the neck of the uterus, is, in the unimpregnated state of the organ, probably not
larger than a common size probe. That portion of the canal called the straight, is still
more contracted. Besides, along the whole course of the canal, there are striae, or
wrinkles, and between which, glands, secreting mucus obviously calculated for the pur-
pose of additional obstruction. Even the proper cavity of the uterus itself, is so ex-
tremely shallow that its two surfaces are nearly m contact.

Such are the impediments incident to a perfectly natural and healthy condition of the
parts. To these may be added others resulting from morbid derangement, or conge-
nital deformities, and which are found to exist as well in the males as the female organs.

1. The penis has its power of ejecting the semen, destroyed or abridged by trunca-
tion, by strictures, by anomalous openings along the course of the urethra, or by debility
and relaxation.

2. The vagina is obstructed or shut up by cohesion of its sides, by membranes of ad-
ventitious growth, or by tumors.

3. The os tincx is sometimes discovered impervious, either from original imperfec-
tion, or by the process of inflammation, and is occasionally rendered utterly, inaccessi-
ble to the semen, by the obliquities, retroversions, or prolapsions of the wombf.

These facts very clearly demonstrate, that conception can take place though the
semen may be deposited merely within the vulva, and seem almost to warrant the con-
clusion, that it never does, as a natural event, reach the cavity of the uterus. Lest,
however, they may not appear to others in the same strong light, in which they present
themselves to us, we will bring to their aid some further evidence.

Experiments have been resorted to in order to decide this point. They have been
made by Harvey, De Graat, Lewenhoeck, Haller, and Heighten. Different animals
were the subject of these experiments. The doe, the cow, the ass, the ewe, the bitch,
the rabbit, were all inspected immediately, or at remote periods, after connexion with
the male, and never except in one instance, could the semen be traced beyond the va-
gina. By Haller it is stated, that he once detected the semen in the uterus of a sheep
forty-five minutes post coitiim. But this is a solitary exception, to the numerous obser-
vations both of himself and others and which can claim little consideration, especially
when it is known that such a result was essentially necessary to the maintenance of a
favourite hypothesis.

As auxiliary to this single experiment of Haller, it is, however, urged that Morgagni
saw the semen in the uterus, and Ruysch in the fallopian tube of the human species*
Without impeaching the veracity of either of these illustrious men, we may be permit-
ted to remark, that their observations have never been confirmed, and that under the
circumstances in which they were made, it is reduced almost to a moral certainty that
they mistook for semen what was in reality the mucus of the parts. But, conceding to
these alleged facts all that can reasonably be required, what do they amount to ? Con-
trasted with the vast mass of counter evidence, they dwindle into insignificance and will
not weigh as dust in the scale.

It appearing, therefore, that the semen does not enter into the uterus, it becomes su-
perfluous to inquire respecting the practicability of its conveyance by the fallopian tubes.
The latter problem is merged in the former. But to silence all cavils, we will give the
question a cursory examination.

That the fallopian tubes are not subservient to this purpose, is very distinctly indica-
ted by the peculiarity of their structure. Commencing with an aperture so very minute,
as hardly to admit a common bristle, the canal gradually enlarges, and finally terminates
in a wide and patulous mouth. Now, were they destined to convey from instead of to
the utenis, would not the construction be directly the reverse of what it is ? We know
that they conduct the product of the ovary to the womb, and we see that the extremity

* See APPENDIX, Note 1 1.

f Each of the above positions is supported by cases to be found in the writings of
Harvey, Morgagni, Hildanus» Ruysch, Mauriceau, Simpson, Guillemeau, Haller, and in
the periodical journals.

After distinguishmgthe true from the probable, an indispensable duty
in every science of facts and observations, like physiology, I shall pro-
ceed to state the hypothesis, which appears to me the likeliest, on the
manner in which the two sexes concur in the production of the new
being.

CCV. The foetuses pre-exist in the ovaria of the females, not that they
are there since the creation of the world, as Bonnet believed, and all who
embraced the doctrine of that metaphysical naturalist j but the ova con-
taining his germs are formed by the proper action of the ovariutn which
secretes them, a fresh proof that all the phenomena of organized bodies,
whether for the preservation of the species or of the individual, are effect-
ed in the way of secretions. This ovum, produced by the elaboration of
the blood which the spermatic vessels carry to the ovaria, contains the
lineaments of the new being ; but it is only the sketch, or carcass of it, if
this may be applied to what has not yet lived. The seminal fluid must
bring it out of this state of inactivity, and, with something of an electri-
cal power, waken it into life. The eggs laid by a maiden hen, will never
hatch, though there are in them the rudiments of the chick. The eggs
of a frog that has been kept apart from the male, during the whole time
of spawning, putrify in the vessel of water they are kept in: if the male,
on the contrary, if sprinkled with his semen, as they quitted her, they

is adapted to this office. It is almost as well ascertained that they convey nothing- from
the uterus, and the orifice is fashioned accordingly.

By assigning to the tube this function, we moreover invest it with a power of a two-
folti action, precisely opposite, of which there is no analogy in the animal economy. The
inverted periastalic motion of the intestines, comes nearest to an example, but it will
not hold. The cases are not parallel, the action of the intestine being preternatural,
the effect of violence and disease. It is useless, however, to protract this discussion, as
we have proof at hand which is absolutely conclusive. By the experiments of Mr.
Haighton, it is ascertained that the tubes do not change their position to grasp the ma-
tured vesicle till the whole process of conception is consummated in the ovary.

"I found," says this eminent physiologist, " from a series of observations made on
different rabbits, at every hour between the 1st and 9th, that the iimbrix remained
nearly in their usual situation, and the only difference 1 found in the last hour, was a
greater turgescency of vessels, as if preparatory to some important action. I desisted
from this inquiry at the 9th hour, because the ovaries bare evident marks of impregna-
tion, and there appeared to be no action in the tubes, by which the semen could be
conveyed to them."

Convinced that the hypothesis in its primitive shape was no longer tenable, some of
the advocates of impregnation by contact, have contended that it is effected by the
emission of subtle exhalation from the semen, termed aura semitiaUs, and which is trans-
mitted through the tubes to the ovary. But here they are again met by the whole body
of facts, and chain of reasoning which drove them from their original position. It has
indeed, been said, and with no want of plausibility, that the volatile vapours from the
semen might penetrate through obstructions which should resist the semen itself. Be
it so : in many instances, it might happen undoubtedly. But still, how can the cases
formerly referred to, be got over, where from organic derangement, the passages were
so entirely occluded, as to be impervious even to air ?

Nor are these the only difficulties that stand in the way of this amended hypothesis.
We are not disposed, however, to enter at present into any further detail. Before we
engage in a lengthened investigation of this sort, we require it to be shown that the
aura seminalis has the property of fecundation. As yet, no such proof has been exhibi-
ted, The experiments of Spallanzani, and Hunter, the only ones which have been made
on the subject, prove indeed quite the contrary. — Chapman.

Dr. Gartner of Copenhagen has demonstrated the existence of ducts leading from
the ovaries to the uterus in the cow and sow, Dr. Dewees of Philadelphia, some years
ago published a new theory of generation, which is predicated on the existence of these
ducts between the vagina and ovaries. See ed. Med. Journal, July 1822. — Godman.

393

will speedily show some developement of life. Their putrefaction may
be prevented, and themselves animated, by shedding on them the sper-
matic fluid, obtained by the process employed by Spallanzani, in his ad-
mirable experiments on artificial impregnation,

It is especially to the labours of this able observer, that we owe what
has been unveiled of the mystery of generation, and of the part which
each sex bears in this function. It is almost proved., that the male co-
operates in it, only by supplying the vivifying principle that must ani-
mate the individuals of which the female furnishes the germs; that thus,
his part is the least essential. It is not so difficult as may be imagined,
to explain upon this system, the striking resemblances which are fre-
quently seen between fathers and sons. The imperceptible embryo has, at
most, the consistency of a slight viscous glue. Such a body must be ex-
ceedingly impressible, and the semen of the male, applied to its surface,
must impress on it powerful modifications. The action of the fluid on
this yet tender embryo must be like that of a seal, which stamps on the
soft wax its own image. The impression is the deeper, the resemblance
the more striking, according to the spirit and energy with which the male
performed the act of reproduction.

The seminal fluid may not merely act on the surface of the gelatinous
and nearly liquid germ, and modify it externally* but it may penetrate so
soft a substance, and impress it on inward changes. It is thus that we
are able to explain, not only hereditary likeness, but also hereditary dis-
eases. Nevertheless, it does appear, that the interior parts are derived
chiefly from the female, while the outward parts are especially influenced
by the male; for, when two animals of different species copulate, their
mule resembles the sire outwardly, and the dam within. It is difficult to
show good reason for the want of the generative faculty in mules. Why
are their sexual parts, so well developed, altogether barren? What se-
cret defect frustrates their action? And why do certain mules, among-
birds, propagate, and in the same manner, hybrid plants, which are real
mules, and not quadrupeds ?

The impregnation of the ovum is effected in the ovarium itself, to
which the semen is conveyed, as has been said. The ovum, stirred by the
action of the semen, and of the fallopian tubs, detaches itself from the
organ which has produced it, and descends into the uterus, by the peris-
taltic contractions of the fallopian tube. This canal is susceptible of a
retrograde motion. It may be conceived, by considering that having
stretched itself, by a real erection, to convey the semen to the ovarium, it
must, in its return upon itself, cause a flow of the fluid its cavity contains,
in a completely inverted direction*. This retrograde motion, as Nisbet
observes, is assisted by a sort of collapse succeding the excitation which
coition had produced: for, the experiments of Darwin prove that the
weakness of the vessels is the cause of this mode of action in their f>ari-
etes. Spongy as the urethra of man, the fallopian tube brings back the
ovum from the ovarium to the uterus. The extra uterine foetations afford
the proof, that matters are carried on in the manner we have stated. Since
foetuses have been found developed, in the ovurium, in the fallopian tube,
and,even in the cavity of the abdomen, when the detached ovum has
escaped from the grasp of the corpus fimbriatumf, one must admit, that
it follows the course which has been described.

* See the Note in the APPENDIX on this subject.

f In extra uterine abdominal conceptions, the ovum which the tube could not hold or

3 D

394

The ovaria, like the testicles, swell and enlarge, at the time of puberty.
They shrink, and wither in some sort, when the woman is no longer
fit for conception. On examination, a, few days after conception, one of
the ovaria, larger than the other, shows a little yellowish vesicle, which
dries up in the course of pregnancy, so that, towards the end, there re-
mains nothing in place, but a very small cicatrix. Is this vesicle, the
outermost covering of the ovum, in which the germ is enclosed,' and
which is torn to allow its escape? The observations of Haller prove that
the corpus luteum is formed by the remains of a vesicle that has burst at
the moment of conception, and allowed the fluid it contained to escape.
In an ewe opened a few minutes after coition, you may see, in one of the
ovaria, a vesicle larger than the others, torn with a little wound, of which
the lips are still bloody. Inflammation comes on in the torn coats of the
small vesicle, fleshy granulations appear, then sink, and a scar shows the
place where it had been. The number of these cicatrices is proportion-
ed to that of the foetuses. It is not known how long the germ detached
from the ovarium remains within the fallopian tube, before it reaches the
cavity of the uterus. Valisnieri and Haller had never been able to per-
ceive it distinctly in this viscus, before the seventeenth day.

The obstruction of the tubes may, as well as the defect or diseased
affection of the ovaria, cause barrenness. Morgagni speaks, on this head,
of certain courtezans in whom the tubes were entirely obliterated by the
thickening of their parietes ; the consequence, evidently, of the habitual
orgasm in which they had been kept, by two frequent excitation. The
structure of these parietes must make obstructions of the fallopian tubes
very easy. Their tissue is spongy, vascular, and seems susceptible of
erection, like the corpus cavernosum of the penis and of the clitoris.—
Their internal coat (the .point of union between the serous membrane
which lines the abdomen, and the mucous membrane within the uterus)
partakes in the inflammation of both. I have often been consulted by
young women on the cause of their sterility: by a close investigation of
the causes from which it might have arisen, I have always found that
they had had, at different periods of life, inflammation of the lower part,
of the abdomen. A young woman, after obstinate suppression of the
menses, exhibited all the symptoms of inflammation of the peritoneum:

seize, rolls into the hypogastric region, and there adheres to some point of the perito-
neum. It is found attached to the mesentery, to the colon, to the rectum;, to the ex-
.ternal part of the uterus, growing- there, and developed, by the vascular communica-
tion which takes place at the adhesion ; but the vessels of the peritoneum are insuffici-
ent for the entire developement of the foetus, which dies, for want of nourishment, in
the first months of pregnancy. The adhesion of the ovum to the peritoneum, is easily
accounted for, by the irritation it occasions : it may be considered as a foreign body, de-
termining, by its presence, inflammation of the membrane, with which it lies in contact
and uniting with it, because it 'brings to this act its own share of vitality. It is really
a union of 'two living parts, not unlike to that which takes place, between the bleeding
lips of a wound, between the pleura pulmonalis, and pleura costalis, 8cc.

But as the serous membranes contain, in their tissue, capillaries so fine, that when in
a healthy state, the blood does not show its colour in them, their vessels never develops
themselves, sufficiently to transmit to the ovum, which has adhered to them, a due sup-
ply of this fluid. The mucous membranes receiving more blood, are able to supply
more; but the placenta cannot adhere to them in extra uterine conception. The mem-
brane which lines the tube, belongs, in fact, as much to the serous as to the mucous mem-
branes; it establishes, as is well known, the only point of communication there is between
the two kinds of membranes. — Author's Note.

395

a year afterwards she married, but never became pregnant, A woman
recovered from puerperal fever, ensuing upon a very difficult first labour;
from that time, with*all the appearance of the stoutest health, she has
never been again a mother.

Do the two testicles, and the two ovaria, contain the separate germs oi'
males and females ? Are these, as has been guessed, contained in the le/t
ovarium, and males in the right? and may we procreate sexes at plea-
sure, by varying the attitude of copulation ? This old opinion, lately re-
vived, besides wanting all foundation, is formally confuted by facts : no-
thing is more common than to see men who have, from some accident,
lost a testicle, procreating sexes indifferently. Women, with an ovarium
deficient, or the fallopian tube obliterated on one side, have produced
both boys and girls. Dr. Jadelot has presented to the society of the
School of Medicine, in Paris, a uterus, wanting the right tube and ovari-
um; and nothing indicated that they had ever existed. On inquiry con-
cerning this woman, it appeared that she had been delivered of a boy and
two girls: Haller quotes similar cases. The cause, then, which deter-
mines the sex, altogether eludes our investigation. Does that one of the
two, who exerts most energy in the act of coition, impress his sex on the
offspring? I cannot tell; but I think I have observed that the marriage
of young people, where both are glowing with love and youth, most fre-
quently produce daughters, whilst boys are ordinarly the consequence of
the union of a middle aged, or elderly man, with a younger woman.

CCVI. Systems of generation. The antique system of the mixture
of the semen in the cavity of the uterus, set forth in the writings of Hip-
pocrates and Galen, is still that of many physiologists. In this system,
the mixed fluid may be considered as an extract from all parts of the
body male and female. A generative faculty* disposes them suitably for
the formation of the new individual. Buffon has further particularized
the facts which this hypothesis requires, and displays its improbability.
Each part, he says, furnishes molecules, which he calls organic, and
these 'molecules, coming from the eyes, the ears, Sec. of the man and the
woman, arrange themselves round an internal mould, of which he admits
the existence, which mould forms the basis of the edifice, and comes
from the male probably, if it be a boy, from the female, if a girl. Rea-
son rejects a theory which gives no explanation of the production of the
placenta, and of the membranes covering the foetus : it is moreover di-
rectly disproved by the good conformation of children, born of parents,
who, not happening to have certain organs and limbs, could not certaintly
supply the proper molecules for their formation in the child.

The system of the ovarists, which at this time stands highest in favour,
numbers amongst its supporters, Harvey, Stenon, Malpighi, Valisni-
eri, Duhamel, Nuck, Littre, Swammerdam, Haller, Spallanzani, Bonnet,
&c. These admit the distinction of animals into oviparous and vivipa-*
rous, in this sense only, that these last hatch within, and break their
shell before they are brought forth. Lastly, Leeuwenhoek, Hartsoeker,
Boerhaave, Mery, Werheyen, Cowper, &c. have added to the opinion of

* All thatBlumenbach has said, on the force of formation, (JHisua formatimt*) Applies
to this generative faculty; it is only a new name given to an old idea. — .Author's J\'ot*.

This " generative faculty,'* will doubtless remind the reader of the " dormitive fa-
.culty" by which Moliere's new made fioctor explained the action of opium.— Gwlman.

396

the ovarists, that the seed of the male contains a multitude of spermatic
animalcules, all capable of becoming1, by developement, beings similar to
their father. These animalcules push forward, along the tubes, upon the
ovaria : there a general engagement takes place, in which all are slain,
save only one, who, master of the field of battle, finds the triumph of his
victory within the ovum that has been prepared for him. This system,
\vnich is not the most probable in the world, assigns to the male the
greater part in the work of generation, since the female is made to fur-
nish merely the coverings of the foetus.

It would be to no purpose to unfold, more at large, opinions hazarded
on a subject so obscure. What I have said is enough to show that those
parts of nature which most obstinately elude our curiosity and afford
most scope to our imagination, are those whfch men believe they know
the best, and on which they speak with most confidence and prolixity: —
so true is it, as Condillac has observed, that we have never so much to
say, as when we set out from false principles*.

* Numerous as are the theories which have been advanced on the subject of gene-
ration, they may all, as mere varieties, (or at least such as are worthy of attention,) be
very properly reduced under two leading heads or general divisions.

1. Doctrine of Palengenesis.

2. Doctrine of Epigenesis.

The first of these doctrines suppose the pre-existence of germs. It is of great anti-
quity, and in its descent to us has undergone some slight modifications- By most of
the early philosophers it was taught, " That these germs created with the beginning
of things, were scattered throughout the world, but ultimately meeting- with appropri-
ate genital organs, effected a lodgment therein, and became fit for developement."

As soon, however, as the moderns entered into speculations of this nature, the hypo-
thesis received a correction which, in part, divested it of its absurdity. Denying- that
these germs wandered about " in quest of an habitation and a home,'*, it was now, on
•;he contrary, maintained, " That all of the same species, were ab initio neatly incased,
one within another, so that the first parent, animal and vegetable, contained the germs
of each succeeding- generation, and which to be evolved required only the seminal im-
pulse of the male."

This doctrine of evolution had been hardly revived, when two sects arose, who urged
their respective opinions with all the zeal, all the ardour, and all the pertinacity of
party controversialists. They differed, however, only on a single point. By the one
side it was maintained, that the germs were furnished by the female, and by the other
that they proceeded from the male.

The former of these opinions was brought into repute by Fabricius ab Aquapendente,
so called from the place of his nativity. Having- ascertained, as he thought, by a series
of experiments on the eg-g, that it contained a pre-existing- embryon, he, with a nume-
rous train of disciples, pushed their investigations, and finally detected, or pretended
to detect, ova also in the viviparous animals.

Enamoured of this boasted discovery, the celebrated Harvey became one of the
warmest and most strenuous supporters of the hypothesis to which it led. " Omnia ex
ovo."

This brief aphorism, which escaped from him in the enthusiasm of his devotion, suf-
ficiently marks his impressions on the subject. The only distinction, indeed, which
he admits in the generative process of the two classes of animals, is, ** That in the vi-
viparous, the feet us begins to exist, increases, and completes its growth in the uterus;
whereas, in the oviparous, the embryo exists in the egg in the body of the hen, but
does not become a fccttts till expelled, and is hatched into life by incubation."

The ovular doctrine was first arranged by Lewenhoek, Who made the discovery of
the spermatic animalcules in the male seed- By him and his followers, the existence
of ova in viviparous animals was speedily and satisfactorily confuted. They demon-
strated to entire conviction, that what had been taken for true ova were the mere vesi-
cles of the ovary, which have no resemblance to an egg, being merely cups or reser-
voirs of a fluid, which after fecundation is discharged and conveyed by the fallopian

397

CCVII. Of gestation. From the moment of conception, there begins
in woman, both in the motion of the solids, and the composition of the
fluids, a remarkable alteration. The change that has taken place shows
itself in all her functions: she exhales a peculiar odour; the child she
suckles refuses the breast, or takes it with reluctance, an$ soon falls away,
if left in the hands of such a nurse.

Nature, occupied with her work, seems to forget every thing else, to
bring it to perfection. It has been observed, that in times of contagious
diseases, even where the plague raged, pregnant women were least ex-

tube to the cavity of the uterus. They further proved, that previously to impregnation
nothing like a germ could be found even in the real egg's, but that there is placed on
the vitellus, a small vesicle, the cicatricula, containing a fluid of the same nature, and
destined for the same end as that in the vesicle of the ovary. The only difference,
therefore, in this respect, between the egg and ovary, according to this sect, is, that
the former has a single, while the latter has a cluster of vesicles.

By this doctrine of spermatic worms, which completely usurped the place of the ovu-
lar doctrine, and which acquired for a time an undisputed ascendency in the medical
and philosophical schools, it was affirmed, that these seminal vermiculi are living minia-
tures of the animal from which they are derived, exacting only from the female a ma-
trix for nourishment, evolution and growth.

Though the ovular doctrine was thus subverted by Lewenhoek and his auxiliaries, it
after a while again revived, under the auspices of Haller, so far at least, as to suppose
the pre-existence of a germ in the female, and soon received the distinguished support
of Bonnet, Spallanzani, Hunter, &c. Being restored in a more enlightened age, it of
course was stripped of most of those extravagancies which had before detracted so
much from its merit. Agreeing in the fundamental principle of the doctrine, these
physiologists entertained some difference of opinion as to the origin, the existence and
develop ement of the germs. They all, however, maintained « that the germ, as the
exact miniature of the animal or vegetable to which it belongs, exists in the female
prior to fecundation, requiring only the stimulus of the male seed to excite it into life,
&c. 8cc.

By thus narrowing1 the definition of the doctrine, they presented it in a guise exceed-
ingly alluring, and rested its vindication on a collection of experiments and observa-
tions, in appearance, the most definite and conclusive. These, however, on a closer
examination, exhibit a very different aspect, so much so indeed that a large number of
distinguished physiologists have been induced, upon the most diligent scrutiny, to
question altogether the pre-existence of germs. It would be wholly inconsistent with
our limits to detail the arguments and reasonings which have been employed by the
adverse parties in this interesting controversy. We proceed next, therefore, to the
doctrine of Epigenesis.

Discarding, as we have already hinted, the notion of the pre-existence of germs, it
presumes that " the prepared, but at the same time unorganized rudiments of the foetus,
first begin to be gradually organized when they arrive at their place of destination, at a
due time, and under the necessary circumstances." This is the definition of a learned
writer. The doctrine, however, may be more distinctly enunciated. We would say,
that, denying the pre-existence of germs in either parent, the doctrine of Epigenesis
supposes, that the fluid contained in the ovarian vesicle is the rude elementary matter,
which, after impregnation, becomes organized into an embryon by the energies of the
semen masculinum. The primary traces of this doctrine are to be niet with in the
writings of Aristotle. The prevailing opinion on the subject of generation, in the time
of this eminent philosopher was, that each sex furnishes semen, and that the embryon
results from an admixture of the two fluids in the cavity of the uterus. After confuting
the popular idea of women having semen, he asserted" that they contribute nothing to-
wards conception, except the menstrual blood ; that the rudiments of the embryon are
derived from the menses, and are vivified and put together by a plastic power, which
he imputed to the semen. With various modifications this hypothesis has been handed
down to us. It would be tedious and impossible to point out all the shapes which at
different times it has assumed. Of late its most able and determined supporter is Bin-
menbach, to whose system of Physiology, and Essay on Generation, we must refer such
of our readers as are desirous of further information on this subject. — Chapman.

39$

posed to infection ; but, at the same time, when they are seized with af-
fections, which in other persons, or at another season, would be without
danger, they sink under them, because these diseases, though at first very
slight, easily put on a malignant character. The progress of mortal dis-
eases is retarded ; a phthisical woman, and who has only a few months
to live, shall prolong her life through the whole term of gestation. The
consolidation of fractures is nothing slower, though Fabricius Hildanus
pretends that the state of pregnancy pats a complete stop to it.

I have never been able to find any difference in the time of formation of
callus, between pregnant women and others. M. Boyer avows the same
opinion*. Among the authors who have asserted that fractures could not
consolidate during pregnancy, some have conjectured that this depends
on Nature; who is busy in directing the humours to the uterus, forget-
ting, in some sort, every other function, and omitting to institute the pro-
cess necessary to the cure. But as we shall see, whatever may be the
importance of the uterus, charged, during pregnancy, with the fruit of
conception, the foetus is merely an organ added to the organs of the mo-
ther, and assimilating to itself the juices it receives from the uterine ves-
sels. It does not hinder the other parts from getting their nourishment:
they all go on living, and separating to themselves the juices their exist-
ence or their functions require. Haller ascribes the difficulty with which
the broken ends unite, in pregnant women, to the great quantity of earthy
matter which the foetus draws off from the mother. This opinion will
not stand; for, as I have shown in my preliminary discourse, the phos-
phate of lime has but little to do in the work of re-union, which chiefly
goes on by changes in that part of the bone which is really organic. Be-
sides, this hypothesis would imply that consolidation were as difficult in
nurses, whose milk carries off a large quantity of phosphate of lime. Yet
it has not been observed that the formation of callus is more difficult du-
ring suckling. Lastly, on this, as on all occasions, experience is more
effectual than reasoning ; now, experience shows, that the time required
for the formation of callus, in pregnant women, is not sensibly longer than
in their ordinary state.

Meanwhile, the uterus, imbued with prolific fluid, swells, to avail my-
self of the expression of a modern, like a lip stung by a bee : it becomes
a centre of fluxion towards which the humours tend from all quarters.
The diameter of its vessels increases with the thickness of its parietes :
these soften, and their muscular nature becomes more markedf. Till
the end of the third month, the only appearance of pregnancy is in the
suspension of menstruation : the uterus, ©f which the cervix has yet un-
dergone no change, has concentrated itself behind the pubis, but very
soon it rises above the upper outlet of the pelvis, pushing upwards the
intestines and the rest of the abdominal viscera. Towards the end of
pregnancy, it rises above the umbilicus, its fundus comes in contact with
the arch of the colon, and reaches sometimes to the epigastric region.
The compression it exerts on the organs of digestion, explains the loath-
ings, and the nausea which belong to the state of pregnancy. The de-
rangement of sensibility, by the affection of the great sympathetic^, ac-
counts equally for those depraved tastes, those fantastic appetites, which

* Lecons de M. Boycr, svir les Maladies des Os, refugees en un Traite coir.plet cle ces
Maladies, par A. Richerand, 2 vols. 8vo.

j- According to M. Lobstein, the uterus, during1 pregnancy, is ixnalagotis to an organ
in a state of chronic inflammation.

' 399

the ignorant think it so important to gratify. When the term of preg-
nancy draws near, respiration is oppressed, the diaphragm forced upward
by the abdominal viscera, descends with difficulty; accordingly, Nature
has, as much as possible, delayed this moment of oppression, by giving
the lower part of the abdomen a great capacity, at the expense of the
chest, which, in women, is much shorter than in men.

If the growth of the foetus, its size, the quantity of liquor amnii, the
developement of the uterus, were always the same, we might settle the
height to which this last organ must rise, at each stage qf pregnancy;
but these conditions vary so much, in every individual, that the terms one
might assign would suit but a small number: let it suffice to have spoken
of the extremes. The uterus tends to rise directly upwards: while en-
closed within the pelvis, it preserves this direction ; but as soon as it has
passed the upper outlet of the pelvis, it is no longer supported, and in-
clines forwards, backwards, or to the sides. These inclinations, if they
go a certain length, constitute those vices of situation which accoucheurs
call obliquities of the uterus- Their direction is determined by the dis-
position of the parts: accordingly, they almost always lie forwards;
either because the upper outlet of the pelvis is naturally so inclined, and
forms, with the horizon, an angle of 45 degrees, or because the lumbar
column, being convex, pushes the uterus, which cannot depress it, upon
the anterior parietes, which yields the easier, the more frequent preg-
nancy has been.

The dilatation of the uterus is not the effect of a simple distension of
its parietes, since these, far from stretching thinner, as the viscus grows
in size, thicken progressively, on the contrary, by the dilitation of ves-
sels of all sorts and the afflux of humours. In this sort of vegetation, the
uterus is really active, and does not give way to any efforts of the foetus.
The cervix of this viscus, which, from its greater consistency, had at
first resisted dilatation, ends by yielding to the efforts of the fibres of the
fundus, on the edges of the os tincae ; the edges of that opening are
attenuated, the cervix effaced, the orifice enlarged, and you may feel
through its parietes, the foetus plunged in the waters which its mem-
branes contain.

Towards the term of gestation, the discharge of urine is more frequent,
because the bladder, under compression, cannot contain it in any quan-
tity; the lower extremities are oedematous ; the veins of the legs vari-
cose; women are also more exposed to haemorrhoids; and these effects
depend on the. compression of the vessels, which bring back the blood and
the lymph of the inferior parts, as the cramps, to which pregnant wo-
men are subject, depend on that of the sacral nerves. The groins are
alike painful, and there are felt in them, twitchings which must be as-
cribed to congestion in the round ligaments of the uterus*. Lastly, the
skin of the anterior parietes of the lower part of the abdomen, distended
beyond measure, cracks, when that of the neighbouring parts has yielded
as much as it could.

Before explaining how the uterus expels the foetus and its coverings, at

* These ligaments, as well as the uterus, manifest, during- grstation, their muscular
character: their vessels enlarge, and their iibres become more apparent, according to
the observations of M. Jules Cloquet, made on the bodies of s everal females who had
died soon after child-birth.

See the Note (I I.) last referred to, in the APPENDIX, for the changes which the nerves
of the ute-us and its appendages undergo during pregnancy.— Copland.

400

the term of gestation, let us consider, a little, this fruit of conception ;
let us study its developement, let us examine the nature of the relations
which it holds with its mother.

CCVIII. History of the fcetus and its coverings. The interior of the
uterus, for a short period after the instant of conception, shows nothing
that leads to a knowledge of the existence of its product. But, at the end
of a few days, there appears a membranous transparent vesicle, filled with
a liquid trembling jelly 5 discovering no trace of organization and life.
But the little ovum begins to grow, parts of the gelatinous fluid assume
more consistence, losing, at the same time, their transparency : one may
then distinguish the first rudiments of parts, an imperfect appearance of
the head, trunk, and limbs. The small ovum, free at first in the cavity
of the uterus, contracts adhesion to this viscus: its whole exterior sur-
face becomes shaggy, and this sort of vegetation is no where more mark-
ed, than in the situation to be occupied by the placenta. Meantime, to-
wards the seventeenth day, the p!arts which showed merely a homoge-
neous semi-transparent mass, discover a more determinate structure. A
red point appears in the spot of the heart, it is the heart itself, distin-
guishable by the pulsations of its cavities, and the motions of the mole-
cules of the red liquid that fills them. Because the heart is the punctum
baliens, it is not therefore to be concluded that it is \X\tprimum vivens. All
our parts are formed together, all are coeval, as Charles Bonnet has said;
only they discover themselves earlier or later to the eye of the observer,
according as the nature of their organization is adapted to the reflection
of light*. Were we to admit a successive order in the formation of our
organs, the brain and the nervous system might exist before the heart,
without being perceptible from their transparency.

Meanwhile, red lines, setting oft' from the heart, sketch the course of
larger vessels, and seem agitatated by the action of these tubes, whose
parieties are still semi-transparent. As the blood, or rather its red part,
extends from the centre to the circumference, the forms become more
determinate, the parts unfold and grow rapidly : points quite opaque, are
seen, and the form of the foetus may be distinguished. Bent upon itself,
the foetus is not unlike a French bean, suspended by the umbilical cord,
which, as I shall mention by and by, formed with the foetus and its co-
verings, proceeds in growth with them: it swims amidst the liquor amnii,
cnanges its position the more easily, as the space, in which itis enclosed,
is greater, compared to its size. As it grows, it stretches out a little,
without ceasing, however, to retain hs bent posture CLXV1:) the head
composes the greater part of its body : the upper limbs, like little buds,
pullulate first, then the lower limbs: the feet and the hands appear im-
mediately attached to the trunk : the fingers and toes show themselves
like little papillae. Of all the organs of sense, the eyes are the first ap-
parent: they are discernible, as two little black spots, by the end of the
first month ; the eyelids are produced and cover them. The mouth, at first
gaping, closes by the drawing together of the lips, towards the end of
the third month. During the fourth, a reddish coloured fat begins to be
disposed in the cells of the mucous tissue, ancbthe muscles already exert
some action. The growth is ever more rapid, as the foetus draws nearer
to its birth. It is impossible to assign the weight and the length of the

* The opinion of Bonnet alluded to above, rests on no observation that can even lend
it a collateral support. We have every reason, on the contrary, to infer, that a succes-
sive order in the formation of our organs is observed. See some remarks on this subject
ui the ArrusDii'. Note 1 1.

401

foetus, at the different stages of pregnancy, since the time of conception
is never very certain, and further, the progress of growth varying much,
one foetus at six months shall be as large as another at the full term. Ne-
vertheless, at the time of birth, the body is commonly eighteen inches
long, and weighs from seven to eight pounds.

The secretion of bile, like that of the fat, seems to begin, towards the
middle of gestation, and tinges the meconium yellow, a mucus previously
colourless, which fills the digestive tube; a little while after, the hairs
grow, the nails are formed about the sixth or seventh month ; a very thin
membrane, which closed the pupil, tears, by what mechanism is unknown,
and the pupil is seen. The kidneys, at first manifold, that is to say,
formed each of from 17 to 18 separate glandular lobules, unite, and form,
on each side, a single viscus. Lastly, the testicles, placed at first, at the
side of the lumbar column, and aorta, near the origin of the spermatic
arteries and veins, then carried along the iliac vessels to the inguinal rings,
directed by the cellular cord, (which Hunter calls the gubernaculum testis,)
clear this opening, carrying along with them the portion of the perito-
neum which is to form their tunica vaginalis, and the inferior fibres of
the smaller oblique muscle.

This covering of the testicles, furnished by the peritoneum, not only
covers these organs, and is reflected again over them, but also rises, in
adults, about half an inch high, along the lower part of the spermatic cord.
If it do not reach, it is said, to the inguinal ring, it is because the whole
portion which, after birth, extended from this opening to near the testicle,
has been decomposed, and is reduced to cellular tissue. Upon reflecting
on the causes of the spontaneous decomposition of a portion of this perito-
neal prolongation, it occurred to me, that nothing was less proved, or more
improbable; in fact, in earliest life, the testicles, which have passed out
from the abdomen, by the inguinal rings, are very little removed from this
opening. The portion of tunica vaginalis, which is carried on upon the
cord of the spermatic vessels, rises up to the rings, and even extends be-
yond ; communicating with the peritoneum, as is sometimes seen in con-
genital bubonocele. It is only in the progress of life, that the testicles
descend into the scrotum, still departing from the opening which gave
them passage ; so that, in adults, the prolongation, which at first covered
the whole cord, which, just after birth, was not more than a few lines
long, is found to cover only its lower part, when it is lengthened some
inches, without any necessity of decomposition; a phenomenon, which
it is as as difficult to conceive as to explain. This opinion, suggested,
for the first time, in the first edition of his works, is now almost univer-
sally received.

CCIX. Of the. circulation in the foetus. The principal difference that
is found between the foetus and the new-born child, besides the inactivity
of the senses, and the repose of the muscles subject to volition, lies in the
manner in which the circulation is carried on. Too feeble to assimilate
to its own substance foreign substances, the foetus receives from its mo-
ther, aliments ready prepared. The arteries of the uterus receive a large
supply of blood : this is not all employed for the nourishment of the or-
gan itself, but passes, in great part, from the mother to the child, being
poured, by the uterine vessels, into the cell of a spongy substance, ad-
hering on one side to the uterus, and on the other to the ovum which
contains the foetus.

This cellulo-vascular body, known under the name of placenta, is, as

-s r.

well as the coverings of the foetus and the foetus itself, a product of the
act of generation. Though it adheres commonly to the fundus of the
uterus, it may adhere to any other point of its parietes; sometimes, jeven,
it is placed on its orifice, a circumstance which always makes delivery
difficult. The side by which it is united to the internal face of the uterus,
is uneven, covered with mamillary projections (cotyledons^) which are
sunk in corresponding ceils of the parietes of the uterus, the internal
surface of which, loses, as it developes itself, the smoothness which it
had while empty, as it is furrowed with depressions destined to receive
theplacenta, and studded with projections which penetrate into the cells
of the latter.

The uterine arteries, and perhaps likewise the absorbents which are so
large and numerous in the gravid uterus, that Cruickshank,who succeeded
in injecting them, compares them to quills, thrown out, on the surface of
the placenta, and within its spongy tissue, the arterial blood of the mo-
ther; according to some, these vessels exhale only the serous part of the
blood, and according te others, a chylous, lymphatic, whitish, or milky
substance*. These fluids, effused within the cells of the placenta, are
absorbed by the numerous minute divisions of the umbilical vein, which
by thier union form the trunk of this vessel.

The umbilical vein, arising from the interior of the placenta, by nu-
merous branches, detaches itself from it, and goes towards the umbilicus
of the child, enters his body, at that aperture, ascends, in a fold of the
peritoneum, behind the recti muscles, to the anterior extremity of the
sulcus of the liver, goes along the anterior of this fissure, sending a num-
ber of branches to the lobes of that viscus, especially to the left lobe.
On reaching the right extremity of the transverse fissure, where this last
meets the anterio-posterior, it unites, in part, with the sinus of the vena
portse hepatica, while .the remainder of the vessel, called ductus venosus,

* A German physician, SCHKEGER has suggested a very ingenious opinion on the mode
of circulation, between the mother and child. He believes that the uterine arteries
pour out nothing but serum, into the cells of the placenta. This serum is absorbed by
the lymphatics, whose existence 'he infers from analogy, in this organ and in the um-
bilical cord, in which, however, no one has yet succeeded in injecting them. These
vessels convey it to the thoracic duct, \Vhence it is poured into the left subclavian vein,
and at -last, reaches the heart, which sends it along the aorta. It returns to the placenta
by the umbilical arteries, after being converted into blood, by the actions of the organs
of the foetus. This serosity, after undergoing the process of sanguification, returns
to the foetus by the umbilical vein, and following the well-known course of the foetal
circulation, is subservient to the nourishment of its organs. The branches of the um-
bilical arteries and veins, ramified in the placenta and communicating together in this
spongy tissue, reject through their lateral pores that which can rto longer serve to the
maintenance of the foetus. This residue of nutrition, deposited in the cells of the pla-
centa, is absorbed by the lymphatics of the uterus, which carry it back into the mass of
the fluids of the mother. Not to mention the impossibility of demonstrating the pre-
sence of the lymphatics, in the placenta, or in the umbilical cord, Schreger's hypothesis
ia attended with two objections. How does the nutritious fluid, coming from the mo-
ther and se \ along the aorta of the fcetus to every part of its body, return to the pla-
centa, to be brought back again by the umbilical vein ? Absorption scarcely goes on in
the foetus; the unctuous substance with which the body of the fcetus is covered, pre-
vents that function from taking place on the surface of the body. It goes on with very
little more activity, within the body: the excrementitious secretions scarcely exist before
birth ; whatever is conveyed to the foetus is employed in the developcment of its or-
gans ; hence its growth is so rapid. — Author's Note.

See the remark on the function of the* placenta in the Note (Note II.) in the AP-

403

follows the original direction, and opens into the ascending- or interior
vena cava, very near to the spot where this vein pours its contents into
the right auricle of the hearfc

CCX. The arterial blood which flows along the umbilical vein, acquires
the properties of venous blood, and combines with hydrogen and carbon,
and parts with its vivifying qualities, in flowing along the vessels of the
mother and the tortuous vessels of the placenta. It parts with these
principles, and again becomes vivified* by circulating through the liver,
which, at this period of life^ fulfils the function which, after birth, is com-
mitted to the lungs. Hence the liver and brain form the greatest part of
the weight of a new born child. The former alone occupies the greatest
part of the abdomen. It acquires this bulk, by assimilating to itself the
hydrogen and carbon of the umbilical blood. Its substance is adipose,
oily^ and contains these two principles, in a considerable proportion.
The secretion of the bile and that of the fat, the only secretions that are
manifestly carried on in the foetus, may besides supply, very well, the
want of respiration*.

The blood conveyed by the umbilical vein into the lower vena cava, and
deposited by that vein into the right auricle, does not unite with that
which is brought by the descending cava, from the upper parts, for as
was observed elsewhere, the orifices of these two vessels not being di-
rectly opposed to each other, the columns of blood which flow in them do
not meet each other. That which is brought by the lower cava, passes
through the foramen ovale, towards which the mouth of that vessel is
turned; it passes into the left auricle, thence into the left ventricle, with-
out circulating through the lungs, which containing no air and being dense
and indurated, could not have received it ; the contractions of the left
ventricle send it into the aorta, the force of its impetus is broken, by
striking against the great arch of this artery. It enters into the vessels
which arise from it, and these convey it directly to the brain and upper
parts. This blood is the most pure, the most oxygenated, and that which
comes most immediately from the placenta ; it has not yet circulated in
the body of the foetus, with the exception of a very small quantity brought
from the pelvis and lower parts, for, the blood which comes from the
abdominal viscera, is purified in passing through the liver. The other
parts of the body receive, on the contrary, blood very imperfectly oxy-
genated, since the very inconsiderable quantity which the contractions
of the left ventricle of the aorta have not been able to send into the ves-
sels arising from the arch of this vessel, mixes with the venous blood
which is brought by the ductus arteriosus, immediately below this cur-
vature. Hence the growth, which is always relative, not only in respect
to the quantity, but likewise to the vivifying qualities of arterial blood,
is much more rapid, before birth, in the upper parts, so that the brain
alone constitutes the greatest part of the body, and the shoulders, the
chest, and the upper extremities, are developed, in a much greater de-
gree than the abdomen, and especially than the pelvis and lower extre-
mities.

The blood which is brought by the descending cava, from the upper
parts of the body of the foetus, passes into the right ventricle which forces
it into the pulmonary artery ; this vessel sends only two small branches to
the lungs, and terminates, by a vessel called the ductus arteriosus, into

* See APPENDIX, Note 1 1,

404

the aorta, immediately below the origin of the left subclavian arterr. The
aorta, at its origin, is therefore filled with arterial blood, sent towards
the upper parts of the body, by the contraction of the left ventricle, while
the remainder of this artery contains venous blood, which is expelled by
the combined action of both ventricles.

It is impossible, in this arrangement, not to recognize an evident design.
In fact, if the whole force of the heart had been exerted to send the blood
towards the brain, the delicate texture of this viscus would have been
injured by it ; the combined action of the two ventricles was, on the con-
trary,.required, to enable the blood to circulate, along the extensive and
tortuous channels of the umbilical cord and placenta. The aorta, on
reaching the body of the fourth or fifth lumbar vertebra, divides into the
two umbilical arteries; these send to the pelvis and to the lower parts,
only very insignificant branches, which convey blood that contains a very
small quantity of oxygen ; they then bend along the sides of the bladder,
incline inwards, approach towards the urachus, pass out of the abdomen,
at the umbilicus, and -joining the umbilical vein which had entered,
through the same opening, into the body of the foetus, form with it the
umbiiiral cord.

CCXI. The length of the umbilical cord, measured from the umbili-
cus to the placenta, is from twenty to twenty-four inches. It may be not
above six inches long, or may greatly exceed that length, as is proved by
a case of M. Baudelocque, in which the umbilical cord was fifty-seven
inches in length, and passed seven times round the child's neck; which
circumstance, by the way, shows that the foetus moves in its mother's
womb. Of the three vessels which form the umbilical cord, two, which
are the smallest, have an arterial structure, though they convey blood
that is truly venous, while the umbilical vein carries arterial blood to the
foetus. The umbilical arteries, on reaching the placenta, divide, and are
lost in its substance, in a multitude of vessels whose extremities deposit,
into the areolae of its tissue, the blood coming from the foetus, and which
is to be returned to the mother. Does the course of injection, from the
umbilical vein into the arteries, prove that there exists an anastomosis
between the extremities of these vessels ?

The foetus is connected to the mother, by the umbilical cord and placen-
ta ; the veins, or the lymphatics of the uteras, and perhaps both these
sets of vessels, take up, in the spongy tissue of the placenta, the blood
that has been employed In the nutrition of the foetus, and return it to the
mother, that, after undergoing a change by the action of her organs, and
especially by that of the atmospherical air, by means of the pulmonary
circulation, it may become fit for the nourishment of the foetus. Whether
we inject the uterine vessels, or whether we force the wax along the um-
bilical vein, it never fills but a part of the placenta, which has led to the
division of this substance into two parts, the one belonging to the mother,
which has been called uterine, the other, called the foetal portion, which
forms a part of the umbilical cord.

The vessels of the mother do not, therefore, anastomose with those of
the fretus within the placenta, the circulation is not continued from the
one to the other. If the communication were immediate, the beats of
the pulse of the child ought to be simultaneous with those of the mother,
whereas they are much more frequent, as may be observed, at the time
of birth, before the division of the umbilical cord. If the veins of a bitch,
ready to whelp, arc opened, the animal dies of hemorrhage, and her body

405

remains bloodless. The placenta, however, is empty, only in the part
that adheres to the uterus, the rest of the placenta, as well as the foetus,
are filled with blood, as usual. It is obvious, that if the vessels of the
uterus had been directly continuous with those of the placenta, delivery
would not have taken place, without their being torn, alarming hemorr-
hage, inflammation, and even suppuration of the uterus would have been
the consequence. Lastly, the force with which the heart and arteries of
the mother impel the blood along her vessels, would have been attended
with danger to the organs of the foetus, which are too soft to sustain,
without injury, so violent a shock. Though the placenta and the umbili-
cal cord form the bond of union between the foetus and the mother, it
must be confessed, that they belong chiefly to the former, and may be
considered as a continuation of its body.

- CCXIL The existence of the foetus is solely vegetative; he is continu-
ally drawing from the juices, which the vessels of the mother send to the
placenta, what is to serve to his nourishment and growth. He may be
considered as a new organ, the product of conception, participating in
general life, but having a peculiar life, and to a certain degree, independ-
ent of that of the mother. Bent on himself, so as to occupy the least
possible space, he cannot be considered as asleep ; for not only are the
organs of sense and of motion in a perfectly quiescent state, but, besides,
several of the functions of assimilation are inactive, as digestion, respira-
tion, and most of the secretions. The foetus performs, in the midst of
the liquor amnii, spontaneous motions which accoucheurs reckon among
the signs of pregnancy. The existence of these phenomena has been de-
nied, and the displacement of the foetus has been ascribed to a mere
shaking of the body: this was asserted on the ground of the intimate
connexion between respiration and muscular motion. It was said, that
the blood of the foetus, not being impregnated with oxygen, in its passage
through the lungs, contractility would not exist. But besides, that a fact
may be certain, without being easily explained, it may be answered, that
the mother fulfils this office for the foetus, and sends it arterial blood, fit-
ted to maintain the contractility of the muscles.

As we perform no motion, but in virtue of impressions previously re-
ceived, and as the organs of sense, in the foetus, are completely inactive,
it is not easy to say, why it should move in the womb. The touch, how-
ever, is exerted, when any part of the surface of the body of the foetus
comes in contact with the internal part of the cavity in which it is con-
tained. Lastly, the internal impressions experienced by the great sym-
pathetics, may act as an occasional cause of such motions.

The foetus is nourished, like every other organ, by appropriating to it-
self, whatever is suited to its nature, in the blood brought to it, by the
vessels of the uterus. The interception of this fluid, by a ligature, or by
compression of the umbilical cord, would occasion death, though not, as
has been imagined, by a sudden and quick suffocation, but the action of
the organs would become gradually weakened, and at last cease, when
the fluids of the foetus, being no longer vivified by the mixture of new
juices from the mother, would be completely deprived of their nutritive
parts. It is now well ascertained, that the liquor amnii does not serve to
the nutrition of the foetus, whose mouth is closed, whose head is bent on
his breast, and whose intestinal canal is filled with a fluid different from
that in which the whole body is immersed. Besides,*may not the unctu-
ous substance with which the surface of the skin is covered, prevent the

406

absorption which might otherwise take place, from the outer part of the
body*?

It was long believed that the fcetus was in an upright position, during
the first months of life,- but that, towards the end of pregnancy, it fell into-
a different position, and lay with its head downwards. This errone-
ous opinion, believed from its antiquity, and because it was admit-
ted by several physiologists, is completely refuted in Professor Baude-
locque's work on miduifery. The absurdity of this hypothesis is mani-
fest, if it be considered that the head of the embryo, the most bulky and
weighty part of the body, must necessarily occupy the most depending
part.

The plumpness and the strength of the feetus do not altogether depend
on the strength of the mother. Corpulent and strong women often bring.
forth puny children, while others who are thin and feeble, bring forth
children plump and healthy. Such instances, however, are exceptions to
the general rule, as, cseterisparibus, the healthy state of the foetus is to be
estimated by that of the mother. The morbid condition of the fluids of
the mother has a considerable influence on the health of the foetus, and is
perhaps the way in which hereditary diseases are transmitted, which, by
others, are ascribed to a diseased state of the semen*

The fcetus is subject to affections of various kinds, whether of sponta-
neous origin, or arising from a germ received from the mother. Foetus-
es have been seen with cicatrices, which clearly showed, that solutions of
continuity, of various kinds, had taken place. A child, born with the loss-
of some limb, has met with the accident, in consequence of some affec-
tion experienced in the womb. Professor Chaussier having been called
in to a case of this kind, found the hand and a portion of the fore-arm,
among the membranes!.

CCXIII Of monsters. As it is useful to study Nature, even in her ir-
regularities, I shall say a few words on the subject of monsters, adopting
the arrangement proposed by Buffon, of dividing them into three classes:
the first including monsters from excess ; the second, monsters from de-
fect ; the third including those in which there is a misplacement of or-
gans. In the first, are included those which have superaumerary limbs
or figures, or even two bodies joined in various ways. In the second,
children born with a hare-lip, or who are deficient in some one part. In
the last place, those monsters belong to the third class, in which there is
a general transposition of organs ; when, for example, the heart, the
spleen, and the sigmoid flexure of the colon are on the right side, and the
liver and caecum on the left ; those born with herniae of different kinds,
likewise belong to this class. One may reckon among these monstrous
confirmations, spots in the skin, the colour of which always resembles
that of some of our fluids, but whose various forms are purely accident-
al, though, from prejudice, one is apt to imagine some likeness to objects
longed for by pregnant women accustomed to those fantastic appetites
and longings, so frequent during pregnancy.

Various attempts have been made to account for these unnatural forma-

* May not also this substance, which is the produce of the small sebaceous glands of
the skin, prevent the cuticle from being'macerated in the surrounding fluid, owing to its
being1 repulsive of water, and to its being retained closely applied to the cuticle by the
fine downy hair, or pubescence, which thinly covers the skin during the early periods
of existence. — Copland.

f See the APPENDIX, Note 1 1.

tiotis : some, as Mallebranche, attributed them to the 'influence of the
mother's imagination on the foetus in the womb ; others, as Maupertuis,
thought that her passions communicated to her humours irregular mo-
tions, which, acting with violence on the delicate body of the embryo,
disturbed its structure. Disease, while the child is in utero, is a much
more probable cause of such affections.

If the two foetuses, contained in one ovum, lie back to back, and if the
surfaces at which they are in contact, become affected with inflammation,
it is easy to conceive that adhesion may take place beween them. By
placing, in a confined vessel, the fecundated ova of a tench or any other
fish*, the numourous young ones, which are formed, not having space
sufficient for their growth, adhere to each other, and fishes truly mon-
strous in their formation are produced.

When, from disease, or from an original malformation, the body of
the foetus is deficient in some of its parts, the others are better nourish-
ed and grow to a large size. Hence, in acephalous monsters, as there is
no brain, the blood which should be sent to that viscus, going to the face,
it acquires a remarkable enlargement,

One of the most curious of all the cases of monstrosities, depending on
an original defect in the organization of the germs, is that which was
sent a few years ago, by the Minister of the Interior, to the School of
Medicine at Paris. I shall give an abstract of it, from a more de-
tailed account, drawn up with much accuracy and sagacity by Mr. Du-
puytren.

A young man, thirteen years of age, had complained, from his earliest
infancy, of pain in the left side and lower part of the abdomen. This
side had been prominent and contained a tumour, from the earliest peri-
od of life. At the age of thirteen, he was seized with fever, the tumour
increased in bulk, and became very painful. Some days after, lie voided,
by stool, purulent and fetid matters ; at the end of three months, he be-
came wasted by marasmus, he passed, by stool, a bail of hairs, and in the
course of a few weeks, died of consumption.

On opening his body, there was found, in a cavity in contact with the
transverse arch of the colon, and communicating with it, some balls of
hairs and an organized mass. The cyst, situated in the transverse meso-
colon, near the colon, and externally to the digestive canal, communicated
with the intestine. But this communication was recent and accidental,
and one could plainly see the remains of the septum between these cavi-
ties. The organized mass presented, in its forms, a great number of fea-
tures of resemblance with the human foetus, an'd, on dissection, no doubt
could be entertained of its nature. There was discovered in it, the trace
of some of the organs of sense, a brain, a spinal marrow, very large nerves,
muscles converted into a sort of fibrous matter, a skeleton consisting of a
vertebral column, ahead and pelvis, and limbs in an imperfect state;
lastly, a very short umbilical cord attached to the transverse mesocolon,
at the outer part of the intestine, an artery and vein, ramifying at each of
their extremities, where they were in contact with the foetus and with
the individual which contained it. This much is sufficient to establish
the distinct existence, as an individual, of this organized mass, though,
in other respects, destitute of organs of digestion, of respiration, of the se-
cretion of urine, and of generation. The absence, however, of a great num-
ber of the organs necessary to the maintenance of life, should make it be
considered as one of those monstrous f'cettises, not destined to live be-

468

yond the moment of birth. This foetus was evidently contemporary with
the boy to whose body it was attached. Similar to the product of extra
nterine conceptions, it received its nourishment from that which may be
considered as its brother, and whose germ had originally inclosed its own.
During the thirteen years of the life of Bissieu, (this was the name of
the subject of this singular case) the organized mass obtained from the
mesocolon, by means 6f vessels of its own, the blood necessary for its ex-
istence; this blood, propelled by the organs of circulation into the body
of the foetus, returned afterwards to the mesocolon of the boy who had
so long been to him as a mother. /ft last, the period fixed by Nature for
expulsion beig arrived, and this expulsion being impracticable, the Cyst
became inflamed ; the inflammation extended to the intestine, the part
which separated these two cavities was destroyed, and the cyst opened
into the colon 5 pus and hair were voided by stool, and the patient died
of marasmus. The drawings of different parts of the body of this foetus,
taken by M. Cuvier and M. Jadelot, render this interesting case most
complete. They will be published in the first volume of the transactions
of the Academical Society, near the Faculty of Medicine at Paris*.

We ought not to be ready to place implicit confidence in the extraor-
dinary stories contained in the older, writers, and even in some of the
moderns. In reading the periodical publications of the seventeenth, and
even of the eighteenth century, one is apt to wonder at the marvellous
things which they contain. Among other strange cases, is that of a girl
that was born with a pig's head ; another of a woman who was deliver-
ed of an animal, in every respect, like a pike. There was a time, says
a philosopher, when philosophy consisted merely in seeing prodigies in
nature.

CCXIV. Of the coverings of the foetus. The name of after-birth is
given to the envelopes of the fcetus, because they are not expelled from
the uterus, till after the birth of the child. The ovoid sac, which con-
tains the foetus, is formed by two membranes in contact with each other.
The name of chorion is given to that which, by its external and shaggy
surface, adheres to the inside of the uterus, the other, a concentric mem-
brane to the former, but of less thickness, and to be considered as the se-
cretory organ of the fluid which fills the ovum, is called the amnion.
The third envelope, admitted by Hunter, and called by that physiologist,
the membrana decidua, is nothing more than the languinous tissue pre-
sented by the external part of the chorion, after tearing the multitude of
cellular and vascular filaments, by means of which the ovum adheres to
the uterus. The placenta is itself merely a thicker portion of nearly the
same tissue, in which the umbilical vessels are ramified. The uterus is
also thicker at the part which corresponds to the placenta, because
it is there that the communication of the fcetus with the mother is estab-
lished*.

* Mr. Young of London, has communicated a case of the same kind, in a valuable
paper inserted in the first volume of the Medico-Chirurgical Transactions. In Mr.
Young's case, the foetus was contained in a cyst that seemed to answer the purpose of
membranes and placenta ; it was without a brain, but had imperfectly formed digestive
organs and external organs of generation. — See vol. 1st of the Medico "Chirurgical Trans-
actions — Trans.

f The membrana decidua, a perfect epichorion, as it has been culled by M. CIIAFSIKU,
is the result of the generative orgnsm. It is formed on tiie internal surface of the uterus

409

The liquor atrinii is a serous fluid, of a sweetish odour, of insipid taste,
rendered slightly turbid by a milky substance which it holds suspended,
and somewhat heavier than distilled water, 1,004. It is almost complete-
ly aqueous; albumine, soda, muriate of soda, and phosphate of lime, dis-
covered in it by MM. Buniva and Vauquelin, forming only 0,012 of the
whole mass. It turns of a green colour, tincture of violets, and reddens
that of turnsol; a very remarkable circumstance, as is observed by the
last mentioned philosophers and indicating the co-existence of an alkali
and of an acid in a separate state. The latter is, in so small a quantity,
so volatile, and so soluble in the liquor amnii of woman, that it has never
yet been obtained by itself: there is found, however, in the liquor amnii
of the cow, a peculiar acid, called by MM. Buniva and Vauquelin the
amniotic acid. The liquor amnii is in greater quantity, in proportion to
the size of the foetus, according as the latter is nearer the period of its
formation. It is the product of arterial exhalation. Its materials are
supplied by the bljod conveyed by the vessels of the uterus. This is
proved, not merely by analogy, but likewise by observing the connection
between the qualities of the liquor amnii and the regimen of the mother.
In a woman who had used mercurial friction, in the course of her preg-
nancy, the liquor amnii was observed to whiten copper*.

The fundus of the bladder, in quadrupeds, is continuous with a canal,
of which the rudiments are observed in man, and which is called the ura-
chus. This canal joins the umbilical vessels, passes out with them at
the umbilicus, and terminates in a membranous sac, between the chori-
on and amnion ; it is called the allantois: it is always found in the foetus
of the. lower animals, but it is very indistinct, and often does not exist in
man. Some anatomists say they have seen the urachus sri sing from the
human bladder, and which is commonly ligamentous, terminate in a
small vesicle, which some of them compare to a melon seed ; while
others say its bulk does not exceed a millet or hemp seed. So small
a vesicle can certainly answer no purpose; the urachus always forming
a solid cord, seldom pervious, and even of very small bore, in- the part
nearest the fundus of the bladder. The existence of these parts furnishes
an additional proof.of what was stated in speaking of the uses of the valve
of the caecum, viz. that there are in the animal body, organs which an-
swer no purpose, and' which merely indicates the plan which Nature has
followed in the reproduction of beings, and the gradations which she has
uniformly observed in the divisions of the speciesf.

CCXV. Of the natural term of gestation. The foetus may exist
without the maternal influence, when arrived at the period of seven or
eight months from the instant of conception. All accoucheurs agree that
it may be delivered alive, at this period, and that it stays two months
longer in the uterus, only that it may gain more strength, and be better
fitted to resist the new impressions which it is to experience, on coming

from the irritation excited by the act of impregnation. It serves to unite the ovum to
the interior of the uterus; and, although the ovum may never reach this viscus, the de-
cidua is developed, notwithstanding, on its internal surface. This circumstance is al-
ways observed in extra-uterine fetation.

* M. Laissaigne has discovered a gas composed of 78,3 of azote, and 21,7 of oxygen
in the liquor amnii of some inferior animals. This gas is respirable and supports
combustion — .See Archives de Medecines, Juin. 1823.

t See the APPENDIX, rfote 1 1.

3 F

410

into the world. A child, however, has been known to live, though born
at the sixth month of pregnancy, in premature labour ; but, in general,
the child is the more likely live when born at the usual period ; that is,
towards the end of the ninth solar month, or of the tenth lunar. It is ob-
served, that children born at seven months, however robust they may
prove afterwards, are very feeble when born, have their eyes clos-
ed, and are in a, state of extreme debility and suffering, during the two
months which they ought to have spent in their mother's womb: this proves
how necessary it is that gestation should be carried on to the end of the
ninth solar month.

If the foetus may live though separated from its mother, before the
natural period, may it not, likewise, remain longer within the womb,
grow with less rapidity, and be expelled some days, weeks, and even
months later? How difficult, therefore, will it not be to assign a precise
term, beyond which we shall not be able to admit the possibility of a late
birth !

There are said to be authentic cases of children born more than ten
moths after conception ; yet the laws, which cannot be founded on rare
exceptions, do not allow of so long a period in deciding on the legiti-
macy of children born after the dissolution of matrimony.

CCVI. Of parturition. When the foetus has remained sufficiently
long within its mother's womb, to acquire the degree of strength requir-
ed for its insulated existence, it becomes separated from her carrying
along with it the parts which inclosed it, and by which it was connected
to the uterus. Its expulsion from the uterus is called delivery. The
most riduculous opinions have been entertained, with regard to -causes
which determine the coming on of labour: according to some, Fabricius
of Aquapendente, for instance, it is the want of fresh air, which makes
the foetus rupture its membranes; according to others, the foetus is de-
termined to the same process, by the necessity of voiding the meconium,
an excrementUious fluid, which fills the intestinal canal. It has been said,
that the foetus was urged to it by the want of food, or that labour de-
pends on the re-action of the fibres of the uterus, which, distended beyond
measure, towards the end of pregnancy, close on themselves, and over-
come the resistance of the cervix uteri, which is thinned and gradually
dilated. But, if this last hypothesis be correct, and it is the only one
that is, at present, in any esteem, how comes it, that in a woman, whose
uterus is of a determinate size, labour does not come an, when there are
twins, at the end of four months and a half, by which period, the same
degree of distension would be produced, as by one child at the full
time?

It is very true, that for a fortnight and even sometimes for a month,
before labour, the uterus seems to be preparing for the expulsion of the
fetus. This, at least, may be inferred from the prominence of the cer-
vix of the uterus, which may then, sometimes, be felt ; and which is
evidently produced by the membranes containing waters, which in-
sinuate themselves within the orifice of the uterus, when this organ
contracts, and which collapse and recede, when the uterus is relaxed.

The product of conception, after a certain time, reaches a period at
which it may exist, separated from the mother. When this period is
arrived, the ovum in which it is contained, detaches itself from the
uterus, by a mechanism, in every respect, similar to that by which the stalk
of a ripe fruit drops from the bough on which it hung. Then in all pro-

411

bability, the foetus refuses to admit the blood sent to it by the umbilical
vein. The placenta becomes affected with congestion; the stagnation of
the fluids extends, gradually, to the uterus, and to the neighbouring
parts. Stimulated by their presence, these organs are called into ac-
tion, the woman feels wandering, irregular pains, similar to cholic
pains, which become more acute, are attended with a feeling of con-
striction, and act from above downwards, that is, from the fundus to
the cervix of the uterus. This contractile cavity, assisted by the dia-
phragm and abdominal muscles, then acts with redoubled effort to expel
its contents. The pains become more acute and frequent ; the face red,
the pulse full and frequent, the whole body seems to partake in the affec-
tion of the uterus, and is agitated with convulsive motions. The mem-
branes, filled with the waters, force themselves like a wedge, through the
mouth of the uterus, whose edges are much weakened ; the throes of la-
bour increase in strength and number, the membranes rupture, the liquor
amnii escapes, the head of the child follows, and it soon clears the mouth
of the uterus with most excruciating pains.

These pains are particularly severe, when the sacrum not being suffi-
ciently concave, the nerves of the sacral plexus are violently compressed
by the head of the foetus; this part of the body, almost always, presents
first; it passes through the upper outlet of the pelvis, in an oblique di-
rection, the occiput being turned forward, and corresponding to one
of the acetabula, while the face is directed backward towards one of
the sacro-iliac junctions. It passes thus along the greatest diameter of the
pelvis, but in descending lower down in the pelvis, it describes a portion
of a circle, and passes through the lower outlet of the pelvis, at its
greatest diameter, which is from the fore to the back part. The head
descends through the vagina, appears outwardly, soon disengages it-
self, and is followed by the shoulders and the rest of the body. Thus
it is, that Nature, after having produced fecundation by an act attend-
ed with pleasure, expels the product of conception in the midst of
pain.

CCXVII. The passages, along which the foetus is carried out of the
body, would be too confined, in their ordinary state, to allow expulsion
to take place without laceration, if, as I am going to explain, Nature
had not disposed every thing to facilitate labour. In fact Nature has
not only formed the foetal skull of several flexible pieces, separated by
membranous unossified spaces, so as to allow the bones to move one
another, and the whole head to be reduced in size in passing through
the female pelvis; but she has, besides, united the bones of the pel-
vis, in such a manner, that their articulations become evidently relax-
ed towards the end of pregnancy. During the progress of pregnancy,
the fluids of the mother flow, in every direction, towards the pelvis
and the parts which it contains ; the ligamento-cartilaginous articula-
tions of the pubis, of the sacrum and coccyx, soaked in fluids, unite,
with less firmness, the bones between which they are placed. Hence,
being softened and swollen, they do not force them assunder, like a
•wedge, by increasing their diameters, but facilitate the separation of
the bones, by the passage of the head through the pelvis. Ic is on
the relaxation of the articulations of the pelvis, that the indication for
the operation of dividing the symphysis pubis rests ; an operation said
to have been performed successfully by Sigault and by Professor Alphonse
Leroy.

The foresight of Nature is not limited to the facilitating the motion*
on one another, of the osseous parts of the skull of the foetus, and of the
pelvis of the motner; her care extends to the soft parts of the latter;
these are soaked in mucus, so as to reflux their tissue several days before
parturition, and are so disposed, as was already observed (CCI.) that they
may, without rupture or violence, and by the mere unfolding of the folds
of the skin, yield to a considerable degree. As the placenta and the
membranes are not expelled immediately after the foetus, it is customary
to separate them, by dividing the umbilical cord, near the navel. It is
unnecessary to tie this cord, at the. part near the mother, every communi-
cation being intercepted between the placenta and the uterus, so that no
blood could flow but that of the placenta. Not so, however, with the
part nearest the foetus 5 though the changes which take place in the cir-
culation, at the moment when the chest is dilated, and allows the air to
distend the pulmonary tissue, divert the blood from the umbilical vessels:
•these changes, however, in the circulation of the fluids, might come on
slowly, from the weakness of the new born child ; hence it is always
prudent to prevent, by a ligature, a loss of blood that would increase the
debilty.,

The human ovum is very seldom detached entire, and never so without
considerable danger; that is, the foetus is not expelled with its -mem-
branes and in the liquor amnii, for .these are not, in general, expelled till
a quarter of an hour, half an hour, or even a full hour after the delivery
of the foetus. When the uterus is completely emptied, its cavity be-
comes obliterated by the approximation of its sides ; this organ, con-
tracted on itself, sinks behind the pubis, its cervix closes, and this even
impedes the delivery of the after-birth, when the latter is protracted too
long. The parietes of the uterus, imbued with fluids, are thicker than
in their natural condition ; but they decrease in size, in consequence of
the lochial discharge, and return to their wonted thickness.

When labour is over, the uterus falls as it were, asleep, and enjoys
repose, after painful exertion. The humours cease to be determined to
that organ, towards which they are no longer directed, by any irritation,
and they flow towards the mammary glands, to supply the secretion of
the fluid which is to nourish the new born child.

CCXVIII. Of twins. Though, in the human subject, the offspring
is generally single it is not uncommon for a woman to bring forth two
children at once; it has even been calculated, that the proportion of twin
cases to single births, was one to eighty. Indeed, there are cases of
women who have brought three children at a birth. Haller calculates
that the number of these last, to those of single births is as one to seven
thousand. The cases of four children at a birth, are still less frequent,
and if three children born at once, seldom live long, the others, which,
when born, are at the size of children at five months, cannot live. Only
one or two instances are known of five children, having been born at a
birth ; Haller, therefore, is guilty of exaggeration, in saying that these
cases are to the ordinary cases, in the proportion of one to a million. I
take no notice of the instances in which a greater number are said to have
been delivered at once, because those cases are not well authenticated.
In the case of twins, each child has its own umbilical cord terminating,
sometimes, in a separate, and sometimes in a single placenta. Both foe-
tuses are enveloped in one chorion, but each has a distinct amnion, and
floats in a separate liquor amnii. It would be curious to know, whether

415

in women who have had twins, as well as in animals, one should find two
cicatriculae, both in the same ovarium, or one in each. Twins are gene-
rally, very like one another, in features and dispositons.

The multiplicity of foetuses, in the same pregnancy, is occasioned by
the presence of several vesiculse, ready to be detached from the ovaria,
and consequently ripe for fecundation. This multiplicity of offspring
contributes very little to increase population, for, they are, in general, less
robust and strong, and not so capable of reproduction ; they, besides, ex-
haust the strength of the mother, and their birth is often fatal to her.
The number of children which a woman might bring into the world,
from the period of puberty to the cessation of the menstrual discharge,
would be much greater than it generally is, if no time were lost. Some
women have been know to have twenty-four, thirty, thirty-nine, and even
fifty-three children. A woman died in North-America, after having had
five hundred children and grandchildren, of whom two hundred and five
survived her.

It is now well known, that the number of male children who are born,
exceeds, in general, that 'of the females. The difference, in some coun-
tries, is estimated at one in twenty-one, at a fourteenth, a twelfth, and
sometimes, though rarely, at a third. In all countries of the world, poly-
gamy is, therefore, in direct opposition to the intentions of Nature, and
to the multiplication of the species : this is proved, in a most undeniable'
manner by the loss of population in those countries in which this practice
exists. The boys, more numerous than the girls, during the early part of
life, exposed afterwards, to the dangers of war, of navigation, and occu-
pied in laborious occupations, lead a more laborious and anxious life, and
die in great numbers, so that the equilibrium is soon restored, and the
least numerous portion of the human species, at the cradle, forms about
two-thirds of it, in old age, since we always see more women than men
reach a very advanced age.

CCXIX. Of superf delations. The cases of foetuses bom with unequal
degrees of deveiopemerit, are not to be considered as superfoetations,
but as twin cases. Thus, if in a case of twins, one foetus is of its full
size, while the other is an embryo whose size does not exceed that of a
foetus in the first month; it does not follow that their conception took
place at different and distinct periods, but merely that for some reason
or other, one of the germs has been incapable of growth and develope-
ment.

To settle the question of superfoetations, one should know whether a
woman, with a single uterus, is capable of conceiving two months after
effective copulation. Haller is of opinion, that the cervix of the uterus
is always open to the semen ; but how is the latter to reach the ovaria,
through the adhesions of the chorion to the uterus? It appears easier,
where the two conceptions are separated by a short interval ; thus, the
white woman mentioned by Buffon, who, in the course of one morn-
ing, had connexion with her husband and with a negro slave, bore two
children of different colours. Hence, likewise, it sometimes happens
that one of two twins is, by its features, a living testimony of adul-
tery.

Two children, born with an interval of some months between their
births, cannot be considered as twins, though they may have existed some
time together within the mother's womb. The possibility of such super-

414

foetations is well proved ; they are ascribed to septa, dividing the uterus,
sometimes, into two cavities, merely because such an arrangement would
explain, to a certain degree, how two conceptions might take place, at
some interval from one another ; for it has never been ascertained, by
actual dissection, that any woman, in whom such superfoetations took
place, had a double uterus*.

CCXX. Of suckling. Nothing is more generally known in physio-
logy, than the strict sympathy which subsists between the uterus and

* It seems to me, that a belief in superfoetations can hardly be entertained by any one
•who is conversant with the human economy, and particularly with the changes which
the uterine system undergoes in consequence of pregnancy. We know that soon after
conception, the os tincae, as well as the internal apertures of the fallopian tubes, are
closed by -a deposition of a thick tenacious mucus. But to accomplish still more per-
fectly an end so important to the scheme of" generation as the occlusion of the uterus,
nature resorts to another provision.

By the sprouting forth of minute blood vessels*, or by the effusion of a species of
lymph-j-, or out of coagulated bloodt, a membrane of some firmness of texture is quick-
ly formed. This membrane, which is called decidua or caduca, from its being shed at
the period of delivery, lines completely the uterus, and thus co-operates with the dense
mucus already alluded to, in obliterating the three openings into its cavity.

Such too, is the enlargement of the gravid uterus, and the change thereby produced
in the relative position of its appendages, that a new series of impediments arises to the
frustration of a second conception.

In this state of the organ, it is accurately ascertained, that the tubes lie parallel to its
sides, and subsequently in the progress of gestation, become bound in the same situa-
tion, instead of running in a transverse direction towards the ovaries, with their extremi-
ties lower and fluctuating.

Were an embryon, therefore, to be generated by any anamolous combination of circum-
stances, the tubes could not possibly embrace the fecundated vesicle, and the embryon,
of course, must remain in the ovary, or fall into the abdomen, constituting an extra
uterine conception.

Let us, however, withdraw all the obstacles which have been enumerated to the pass-
age of the embyron, and admit the practicability of its reaching the uterine cavity. What
in this event would happen ? Disorganization'fatal to each foetus must ensue.

It is to be recollected, that the uterus had prepared, in the first instance, whatever
was required for the reception, the nourishment, and evolution of the foetus. It had ori-
ginally supplied it with a decidua, as a medium of attachment, and afterwards with a
placenta for still more important purposes. For the second foetus, the same offices are to
be rendered. These it it could not execute, without suspending the action existing at
the time, and taking on such as are necessary to the fabrication of an additional deci-
dua and placenta.

That actions so incompatible cannot co-exist, strikes me as sufficiently obvious. Were
the uterus, therefore, to attempt this new process, the result would be, the separation
of the primary decidua and placenta, occasioning an abortion, accompanied with haemorr-
hage, which would sweep out the whole of its contents.

It is probably, on this account, that menstruation uniformly ceases with the accession
of pregnancy. I am aware, that this is a point not altogether conceded. The weight
of authority is however, decidedly against menstruation continuing dnring gestation. By
all the very recent writers it is denied. Those who hold, or I might rather say, did
hold the contrary opinion, have mistaken a hemorrhage from the vagina, which some-
times recurs with considerable periodical regularity, for the catamenial flux. Several
cases of this kind have come under my own observation, where I had an opportunity of
inspecting the discharge accurately. In every instance, I found it pure coagulable blood
having neither the colour, nor odour, nor any other of the peculiar properties of the
genuine menstrual fluid.

Haller. f Dr. Hunter. * Mr. Hunter.

415

rnammce ; a connection, in consequence of which, these two organs are
called into action at the same period of life, are evolved, and cease to
perform their functions at the same time, when woman becomes incapa-
ble of co-operating in the reproduction of the species. I shall not en-
deavour to account for this sympathy, by ascribing it to the influence of
the nervous system, or to the anastomosis of the epigastric with the in-
ternal mammary arteries : an anastomosis which is not uniform, for, in-
stead of inosculating with each other, these vessels frequently terminate
in the recti muscles of the abdomen. But even though this anastomo-
sis, should exist, as distinctly as it is often met with in some subjects,
it would not account for this sympathy, since the uterus and the mam-
mae often receive no branches from the epigastric and mammary arteries,
and when they do they are exceedingly small.

The new born child, on being brought in contact with the breast, ap-
plies his mouth to the nipple, and withdrawing his tongue, while, with
his lips, he compresses the edges of the nipple, he draws in the fluid,
whose flow is facilitated by the erection of the lactiferous tubes. These
ducts, from twelve to fifteen in number, not only become enlarged, when
the nipple, which almost entirely consists of them, is elongated by being
drawn out by the child, but, besides, being excited by his touch,
they become affected with a certain degree of erection, and emit their
fluid. This excretion, like that of other glands, is excited by the touch
and the motion of the hands of the child on his nurse's breast. The use of
these gentle compressions, is not so much to express the milk mechani-
cally, as to excite the organ to excretion.

The irritation produced by the child on the nipple, is the most power-

By again adverting1 to the condition of the pregnat uterus, we shall see that a suppres-
sion of the catamenia is exactly what ought to expected. The deciduous membrane is
framed while the process of conception is proceeding in the ovary. The vessels which
had secreted the catamenia are now engaged in a new operation. They form the mem-
brane and then support it. While thus employed, their secretory function is suspend-
ed. They cannot at the sume period, perform actions so incongruous and inconsistent.
The one must yield to the other. This is very strikingly illustrated by the fact which
has not been sufficiently attended to, that in a large proportion of the cases of obstinate
umenorrhea, the membrana decidua exists, and that the first symptom of the return of
the discharge is the coming away of the membrane. Of the identity of the two mem-
branes, there can be no doubt. It has been determined by very competent judges*.

By one less averse than myself to speculative reasonings in matters of science, a va-
riety of considerations of this nature, might be pressed against the hypothesis which I am
combating. It could, I think, in particular, be urged with great plausibility, that chang-
ed as is the whole uterine system by gestation, not only in the mechanical distribution,
but also in the structure and functions of its parts, it cannot possibly assume that peculiar
condition which seems indispensable to conception. Of all the operations of the ani-
mal economy, that of conception undoubtedly requires the most harmoniously concert-
ed action in the several organs by which it is commenced, carried on and consummated.
Derangements in any one portion of this complex apparatus are confessedly productive
of sterility. So essential, indeed to the generative process in the human species, is a
perfect integrity in the functions of the uterine system, that by the suppression or even
vitiation of the catamenia, the aptitude to conception is lost or diminished. But enough
of these speculations ; 1 am content to rest the defence of the question on the facts
which I have stated. If they be correct, it results that superfcctation cannot take place
in the human species.— Chapman.

* Baillie, Burns, &c. &c.

416

fill exciting cause of the determination of milk into the breasts j thru ir-
ritation, or any other of the same kind, issufficient to excite the secretion
of milk, even under circumstances not provided for by Nature. It is
thus that virgins have been enabled to suckle another mother's child ;
that young girls, under the age of puberty, have had so complete a secre-
tion of milk, as to furnish a considerable quantity of this fluid. There
have been known men, in whom a long continued titillation of the breasts
had determined so considerable an afflux of the humours, that there
oozed from them a whitish, milky, and saccharine fluid, not unlike the
milk of a woman. The sucking of the new-born child, is necessary to
keep up the secretion of milk in the mammae. It ceases to be formed in
them, when the child is committed to the care of a different nurse : the
mammae, at first turgid, soon collapse, especially if care have been taken
to determine the fluids downwards, by exhibiting gentle laxatives.

The erection of the breasts, by titillation on the nipple, the spasmodic,
and almost convulsive, action which follows this kind of excitement, may
be carried so far as to produce an emission of the fluid to some distance.
While its excretion lasts, women experience, in their breasts, an agreea-
ble sensation ; these parts are tense and swollen ; they feel, as they express
it, the milk rising; several feel a sensation of extension reaching to the
axilla, to the arms and chest. The whole mass of cellular substance sur-
rounding the breasts and extending to the neighbouring parts, partakes
in their activity.

The breasts, themselves,<:onsist, in great measure, of cellular substance?
an adipose and lymphatic layer, of a certain thickness, covers the gland,
•vvhich is divided into several lobes, and incloses it within its substances.
They receive a number of nerves, but very few blood-vessels for their
bulk.

Their structure appears almost wholly lymphatic ; the vessels of this
kind, after being distributed to the neighbouring glands, and especially
to those of the axilla, penetrate into the breasts, in which their propor-
tion, compared to that of the sanguineous vessels, is as eight to one.
These lymphatic vessels, which enter in considerable numbers into the
composition of the breasts, increase greatly in size in nurses ; and when
injected in this condition, it has been ascertained, that several of them
joined to form larger trunks, which, going towards the nipple, contribu-
ted in forming what are called the lactiferous tubes. If the lymphatic
vessels be immediately continuous with the excretory ducts of the breasts,
there is reason to believe, that it is these vessels which convey the mate-
rials of the fluid which they separate, especially if it be considered, how
small the number of minute arteries which are distributed into their tissue,
and what a disproportion there is between the calibre of these small ves-
sels, and the quantity of blood which the breasts supply. The opinion
that the lymphatic vessels bring to the breasts the materials of the secre-
tion of milk, is not in opposition to the laws of the circulation in the lym-
phatics; all who are acquainted with these laws, know that the course
of the lymph, though in general, from the circumference to the centre,
is naturally liable to a number of aberrations or deviations, facilitated by
the numberless anastomoses of these vessels.

CCXXI. The granulated structure is not as apparent in the breasts, as
hi the other glandular organs, hence they bear a greater resemblance to
the lymphatic, than to the conglomerate glands. The milk which they

417

secrete, has always been considered as very like the chyle, which it re-
sembles in its white colour, its smell, and its saccharine taste. Like the
chyle, it is the least animalized fluid, the sweetest, that on which the ac-
tion of the organs produces the least effect, and that which preserves
most the characteristic qualities of the food taken by the nurse.

It is well known, that instead of giving medicines to infants at the
breast, we most frequently administer the medicine to the nurse ; thus,
the milk acquires purgative qualities, and acts on the bowels of the child,
when the nurse has been purged*. The chyle is white and opaque, only
in those animals which suckle their young ; in the others, it is as trans-
parent as lymph. (Cuvier.)

In the last place, if the arteries carried to the breasts the materials of
their secretion, these vessels ought to increase in size, when these organs
become twice, or even three or four times larger than natural; in the
same manner that, in open cancer, and in other similar affections, in
jwr.hich the determination of blood being increased, the calibre of the ves-
sels is proportioned to them. Nothing, however, of the same kind occurs,
whatever size the breasts may acquire from the presence of milk ; their
arteries preserve their almost capillary minuteness, as I had an oppor-
tunity of ascertaining, by injecting the mammae of a woman twenty-nine
years of a|*e, who died in the second month of suckling, and whose breasts
were remarkable by their size, and by the quantity of milk they were able
to secrete.

Notwithstanding all these reasons, which have long made me adopt the
opinion of the celebrated Haller, who considers the milk as immediately
extracted from the chyle, I own that it must be considered as hypotheti-
cal, and resting solely on probability. The impossibility of demonstra-
ting, anatomically, the branches going from the mesentery to the breasts,
without communicating with the thoracic duct, gives still greater proba-
bility to the generally received opinion, which makes the milk, like all
the other secreted fluids, with the exception of the bile, to be supplied by
arterial bloodf.

The milk does not resemble chyle, in every respect, though it may .be
considered as extracted from the food|, changed in its way to the mam-
mae, by the glands through which it has passed, and especially by the ac-
tion of the organs themselves. This action is so evident, that, as Bordeu
observes, "There are women who seem to have no milk in their breasts,
which are flaccid and empty ; but as soon as the child excites them, they
become distended, and the milk comes spontaneously." It is well
known, and the same author has pointed it out, that women, cows, and
the females of other animals, allow themselves more willingly to be sucked
by a suckling that knows how to excite their sensibility, and to apply due
iritation to the nipple ; and that, on the contrary, they retain their milk,

* This only takes place when such purgatives are used as are readily absorbed into
the circulation.— Copland.

f The passage of injections from the arteries into the lactiferous tubes, and the cir-
cumstance of blood having1 been drawn from an exhausted breast, when the child has
been allowed to suck too Jong- ; and, lastlj;, analogy, leave no doubt of the true source
of the fluid secreted by the mainmie. — Copland.

" Lac utilis aliment! superfluum." Gal. De Usu part. Lib. VII. Cap. XXII.

418

\vhen the suckling does not excite the sensation in which they feel plea*
sure. It is thought, in some countries, that serpents know how to tickle
the teats of cows, and that these animals enjoy this excitement, and allow
themselves to be sucked by these reptiles.

CCXXII. Of t fie physical firofierties of milky and of the chemical nature of
this fluid. The^ quantity of milk is, in general, proportioned to that of
the aliments, to the degree of their nutritious qualities, to their moist
and farinaceous nature. Though it equals, in weight, about one-third of
the quantity of food taken by the nurse, it may exceed that proportion,
or may not come up to it. Its specific gravity, even when the' milk is
.lightest, is greater than that of distilled water, and is always proportioned
to its consistency. The latter quality is in an inferior degree, in woman, but
is greater in the cow, the goat, the ass, and the ewe. Its fluidity is interme-
diate between that of aqueous and oily liquids, its colour, its smell and fla-
vour have something very peculiar, and by which it is easily recognized;
in the last place, it is not exactly alike, at different periods of the same
milking. This is proved by the work of Messrs. Deyeux and Parmentier
on milk, a work abounding in valuable observations, and which may be
considered as the complete history of this animal fluid. They observed,
that the milk first drawn from the cow is serous, that its consistency gra-
dually increases, and that the richest milk is that which is obtained to«-
wards the end of milking, as if the fluid contained in the udder were af-
fected by the laws of gravitation*.

The milk, when exposed to the open air, in a vessel, becomes decom-
posed, like the blood, and separates into three parts ; the serum, the
curd or cheesy part, and the fatty part or cream. The latter, which is
lighter than the others, is always on the surface, and its quantity depends,
not only on the richness of the milk, but also on the extent of the surfaces
by which it is in contact with the air; and this proves, as was first ob-
served, by Fourcroy, that the oxygen of the atmosphere has some influ-
ence on its separation. The caseous part, which coagulates spontane-
ously, appears albuminous, and abounds in oxygen. MM. Parmentier
and Deyeux consider it as the colouring matter of milk, and as giving to
it its most characteristic properties. Lastly, the serum or whey, which
alone constitutes the greatest part of this fluid, contains, besides a pecu-
liar acid, (the lactic acid'] which is formed when this substance is allowed
to remain for some time, a saccharine matter, which may be obtained by
evaporation, and which, when chrystallized in rhomboidal parallepipeds,
constitutes the sugar of milk, whose purity depends on the degree of care
with which the process has been carrkd on. This sugar of milk con-
tains, as Schele first "ascertained, while endeavouring, by means of the
nitric acid, to convert it into the oxalic, a peculiar acid, in the form of a
powder, difficult of solution, and to which he gave the name of saclatic
acid. Milk may be considered as one of the most compound of the ani-
rnal fluids, whose qualities are very valuable, and whose parts have but
an imperfect affinity to each other. So that it is liable to spontaneous
decomposition, and this takes place very easily. This kind of emulsion
contains but a small quantity of asote, so that it retains its vegetable charao

* The author seems to forget that he is speaking of the cow, and that her uddci'
hangs in a situation unfavourable to this hypott»csis.--~7y«7#!?'.

ter. Hydrogen, carbon, and oxygen, predominate in milk ; in the last
place, it contains several salts, amongst others, muriate of soda, muriate
of potash, and phosphate of lime*.

The presence of the two last of these substances leads to the following
considerations. Muriate of potash, as is observed by Rouelle, does not
exist in the blood ; the probability is, therefore, that it is not the blood
which supplies the mammae with the materials whence the milk is se-
creted, muriate of potash being found in greater quantity in milk than
muriate of soda. These salts of potash, on the contrary, are found in
considerable proportions in the chyle, formed from vegetable substances;
which would lead one to think, that milk is furnished by the absorbent
system. The phosphate of lime, which is found in smaller quantity in
the urine of nurses, and which is wholly determined towards the mammae,
was absolutely necessary in a fluid which supplies nourishment to the new
being, while the bones become indurated, and all the parts'acquire soli-
dity.

If we now wish to inquire into the causes which render suction neces-
sary, and which subject the new born child to this peculiar mode of nu-
trition, these causes will be found in the general weakness of its organs.
The organs of digestion would have been incapable of extracting, from
the aliments, their nutritive parts, these substances not having undergone
the due degree of trituration, from the want of teeth and from the im-
perfect state of the other organs of mastication,, It was of consequence,
therefore, that the mother should perform the preliminary function, and
that she should transmit the aliment ready digested!. It is not, however,
to be imagined, that the milk passes, without undergoing any change,
into the vessels of the child 5 the child digests the milk, and obtains from
it, in a short space of time, and without effort, a considerable quantity of
nutritious particles, necessary to the rapidity of its growth.

The connexion between the mother and childis far' from being broken,
at the period of birth 5 the relations between them, though not so close,
are uot less indispensable. Before birth, the vital power was so limited
in the child, that it was necessary it should receive a fluid already anima-
lized, and in a state to yield to the function of assimilation and nutrition.
When the child has breathed, when its strength is increased, it may be
entrusted with a greater share of the process ; it is then sufficient that
the aliment should have undergone the first degree of elaboration, within
the digestive canal. But it is not merely to assist in preparing its food,
that the new born child requires the aid of the mother; its lungs, which
are delicate and imperfectly evolved, do not supply a due quantity of oxy-
gen to the blood which circulates through them : the animal heat would
be under what is required by the wants of life, if the mother did not make
up for this deficiency, by transmitting some of her own warmth. She
folds her infant gently to her bosom, warms it with her breath, and by
this kind of maternal incubation continues to cherish it with that calori-
fic influence to which it was fully exposed, while forming a part of her-
self. Besides, she feels for it, keeps it from danger, foresees its wants,
and understands its language ; and this very interesting intercourse takes

* See the Chapter, at the end of the APPENDIX, on the Chemical Constitution of the
Secretions.
f Lac est dbus exacts con/ectus. Galenus DeUsu partium. Lib. VII. cap. XXU=

, 420

place after the bonds of their physical communication are loosened, but
it does not tear them asunder. The infant is, therefore, detached from
the mother, only by degrees, since it is only in proportion, as it grows
older, that it acquires the means of living independent.

The secretion of milk, in the breasts, may be prevented by irritation
in the uterus. If the labour have been difficult, if the woman have suf-
fered a certain degree of injury, the irritation in the parts so affected
prevents the determination of the fluids towards the mammae. Hence
these organs collapse, during the puerperal fever, not that the milk flows
back into the fluids and becomes the cause of the complaint, but that
the inflammation of the uterus, prevents the fluids from flowing in their
natural direction.

During the first few days after delivery, the parietes of the uterus dis-
tharge a fluid at first bloody, then of a reddish colour, and, in the last
place, mucous and whitish, termed the iochia.

CCXXIII. All the parts of the lungs are not distended with air, in the
first inspirations of the child, after birth. Some of the lobes, which are
harder and more compact, take some time to admit this fluid, and even
sometimes altogether reject it. A child died, twenty-one days after birth,
the body was opened by Professor Boyer. On examining the lungs, he
found that the posterior part of these organs was as hard and compact,
as in the foetal state. The anterior part alone was distended, contained
air, could be felt to crepitate, and floated in water. The heart was ex-
amined, ta ascertain whether its structure was connected with this con-
dition of the lungs, which depended on the want of power in the respira-
tory functions. The foramen ovaie was found pervious, so that the blood
could pass from the right into the left cavities of the heart, without flow-
ing through the lungs. The child had been exceedingly languid during
the whole of its short life ; its skin was at times pale, at others livid. It
was very difficult to keep it warm.

The child of Madame L**** died nine days after birth, with the same
appearances. I -opened the chest, and found the upper part of both lungs
indurated and compact ; the foramen ovale was quite pervious. This
aperture is often closed very imperfectly, so that there remains, at the
upper part of it, an opening, varying in size, which would enable a small
quantity of venous blood to pass from the right into the left auricle, if
these cavities did not contract at the same moment, and if the fluid which
they contain did not present equal resistance on both sides. There are
cases of persons in whom the foramen ovale remained pervious, and who,
nevertheless, lived to an advanced age. Their skin was purple and
livid, all their moral and physical faculties feeble and torpid. It would
be interesting to ascertain, by dissection, whether in good divers, who
can remain a long while under water, without breathing, the foramen
ovale is not imperfectly closed.

* Granting that the foramen remained open, we do not perceive any advantage it
would confer. The system requires blood purified or changed by respiration ; the free
transmission of impure or venous blood from the right to the left side of the heart, could
not answer the purpose of sustaining life, nor would it enable the diver to remain for
any longer time without respiring. In professed divers it is habit alone which enables
them to remain so long under water with impunity. — Godman-

421

CHAPTER XL

\

Containing the History of the dges, the Temperaments, and the Varieties of
the Human Species / of Death, and Putrefaction,

CCXXIV. Of infancy. The epidermis of the new-born babe thickens,
the redness of the skin grows paler, the wrinkles are effaced, the soft
down which covered the face, falls and disappears, the buttocks swell out
and soon conceal the opening* of the rectum. During the first months of
life, it seems to need nothing but nourishment and sleep. In the mean,
while, the understanding is beginning to form, it looks fixedly at objects,
and seeks to take cognizance of all the bodies that surround it. Confin-
ed, at first, to the uneasy sensations, which it expresses by almost continu-
al tears, its existence becomes less painful, as it grows accustomed to the
impressions of outward things upon its delicate organs. Towards the
middle of the second month, it becomes capable of agreeable sensations.
If it feels them before that time, at least it is only then that it begins to
express them by laughing*.

CCXXV. Dentition. Towards the end of the seventh monthf, the mid-
dle incisor teeth of the upper jaw, cut through the substance of the gums:
a little while after, the corresponding incisors of the lower jaw show
themselves : next, the lateral incisors of the upper jaw, those of the low-
er, then the cuspidati, in the same order. At the age between eighteen
months and two years, the small molar teeth appear, but in reversed or-
der, those of the lower preceecling those of the upper jaw. When these
molar teeth have come through, the first dentition is complete ; the life
of the child is more secure : it was before very uncertain, since the calcu-
lations of the probable duration of human life show, that a third of the
children born at any given time, die before the age of twenty-three months.
Convulsions and diarrheas are the most fatal accidents attending difficult
dentition. To these twenty teeth are added two new grinders in each
jaw, when the child has reached the end of his fourth year. These last

* At Hercules risus praecox ille et celerrimus, ante quadraffesimum diem nulli datur.
Plin. Hist. Nat. Pr<ef. ad lib. VIII.

t It would be very difficult to say, why a tertian fever often terminates of itself, when
it has reached its seventh paroxysm, whilst a continued fever is judged of by critical
evacuations, in seven, fourteen, or twenty-one days ; why delivery happens at the end
of nine months : why the first teething- begins at seven months old, the second, at seven
years; why puberty shows itself, towards the fourteenth year, and menstruation is re-
peated at determinate periods. Nature appears to subject" herself in all her acts, to cer-
tain periods, which observation may ascertain, without any possibility of arriving- at u
knowledge of the causes of these phenomena so easy to establish. Because their mani-
festation is corelative to certain numerical terms, we are not to put faith, like Py-
thagoras, in the power of numbers, and believe that the number 3 and the numbers 7
and 9 enslave all nature to their supreme influence. We find traces of this ancient
error in all sciences, in all religions, even in those of enlightened nations.— »#•

422

will afterwards become the first large grinders. They differ from those
that precede them in this, that they are to remain all life long, whilst the
primitive or milk teeth are lost at seven years old, in the same order in
which they appeared, and are replaced by new teeth, better formed, and
larger, excepting the small" grinders, and with longer and more perfect
roots. Towards the ninth year, two new large grinders appear beyond
the others. The child has then twenty-eight teeth, and dentition is com-
plete; though between eighteen and thirty, and sometimes much later,
the dentes sapientise, two to each jaw, show themselves at the extremi-
ties of the alveolar processes.

The order observed in the successive cutting of the teeth is not so in-
variable, but it is frequently inverted. A child ten years old, now under
my care, cut the four first small grinders before the canine teeth. Den-
tition is in this, respect, like all other acts of the living economy : insta-
bility is its principal character. An attentive examination soon shows
how irregularly those phenomena proceed, whether physiological or pa-
thological, which appear the most to be subjected to calculable and de-
terminate periods*.

This double range of successive teeth existed in the jaws of the foetus.
Each alveolar process, at that age of life, contains two membranous folli-
cles, lying one over the other. That which is to form the primitive tooth
swells the first, a calcareous matter covers its surface and forms the body
of the tooth, which invades also the follicle by which the osseous part is
secreted, so that the growth of the little bone being completed, the mem-
branous vesicle, in the parietes of which the dental vessels and nerves
branch out, is found in the centre of its body, and adheres to the parietes
of its internal cavity. It is difficult to say, why the growth of the dental
germs is successive $ why, in the seventh year, the primitive teeth are
detached, and are replaced by others which have remained so long buried
within the alveolar processes. Dentition is like all the other phenomena
of the living economy ; it is subject to endless varieties in its period and
duration, &c. Thus, teeth of a third set have been known to be cut iu
very old people. There are instances, but they are very scarce, of chil-
dren that have come into the world with two incisors in the upper jawfj
there are often supernumerary teeth, Sec.

CCXXVI. Ossification. The process which goes on in the osseous
system, is not confined to the cutting and growth of the little bones which
are. attached to the two jaw 9.^ AH other parts of the skeleton harden; osse-
ous nuclei are formed in the centre of the cartilages, which hold the place
of the short bones of the carpus and tarsus ; the thickness of the cartila-
ginods substances, which separate the epiphyses of the bodies of the
long bones, is diminished ;- the large bones grow, and acquire solidity,
from the centre to the circumference. Those of the skull meet at their
edges, their fibres cross and form the sutures 5 the cartilaginous spaces,

* See Erreurs populaires, sec : edit : Chap. 4. des Jlnnees climaleriquesy et des Jours
critiques dans les maladies.

f Louis XIV. was born in this condition. BAUDELOcauB observes, that the evolution
of some teeth, before birth, is not always connected with an extraordinary growth of
the infant; nor is it always a pressage of a stronger constitution. He endeavours to
prove this by several examples : these, however, may be regarded as exceptions only
from the general, and, we think, correct opinion on the subject. For some remarks on
the production of the teeth, see APFKSDIX, Note KK

423

(fontanele) which were situated at the meeting of their edges and angles,
disappear. The urine contains exceedingly little phosphate of lime, that
salt being entirely taken up in the solidification of the bones. About the
middle of the second year, these have already acquired substance and so-
lidity enough to support the weight of the body; the child can stand
and walk. Before this time, it would be dangerous for him to try it : the
pillars of support, yet too flexible, would yield under the burthen, and
bead permanently in different directions. It is towards the bead, that
the vital motions tend in infancy : accordingly, this part is the principal
seat of the affections peculiar to this age, affections in which it is often of
use to procure local evacuations.

The organs of the senses, open to all sorts of impressions, receive them
with ease ; but if, in early infancy, sensation is easy, it is very transient:
no doubt from the want of consistence in the cerebral organ. As it grows
older, the mobility of the child is lessened, without diminution of suscep-
tibility : and it is during the years that precede the boisterous season of
puberty, that he enjoys, in the highest degree, the faculty of recalling
things that have affected him, that his memory is most distinct and ex-
tended ; but soon overpowered by imagination, roused up by the power-
ful reaction of the sexual organs on the brain, it ceases to have the same
exactness.

CCXXVII. Of fiuberty. Sex, climate, manner of life, have great in-
fluence on the earlier or later manifestation of the phenomena of puberty.
Women reach it one or two years before men: the inhabitants of south-
ern, long before those of northern countries. Thus, in the hottest cli-
mates of Africa, Asia, and America, girls arrive at puberty at ten, even
at nine years old, but in France, not till twelve, fourteen, or fifteen : whilst
in Sweden, Russia, and Denmark, the menstrual discharge, the most cha-
racteristic mark of puberty, is from two to three years later.

The male is known to be capable of generation, and that he begins to
live .the life of the species, by the emission of prolific semen, and the
change of voice, which becomes fuller, more grave, and sonorous; the
chin becomes covered with beard, the genitals with hair, and they attain
rapidly their full size. The whole body grows ; the general characters
which distinguish the two sexes, and which are so obscure, before puberty,
that they may often be mistaken, become very decided, and can no longer
be confounded.

By all these signs of strength and virility, woman, urged by desires
which may be termed wants, recognizes the being capable of gratifying
them. The change of voice is the most certain of the indications of male
puberty. It depends, as the following observations show, on the de\ elope-
ment of the vocal organs, which constantly accompanies that of the sexu-
al parts.

CCXXVIII. A boy, aged fourteen, died in 1799 at the Hospital of la
Charite. On opening the larynx, I was surprised to see it so small ; and
especially the glottis, which was not above five lines in its antero-posterior
diameter, and about a line and a half in its transverse diameter, where its
dimensions are greatest; an observation that must not be omitted, is, that
he was very tall : but that the developement of the genital organs was as
backward as of the vocal. I have repeated the same observation on sub-
jects further from the age of puberty; I have extended my researches to
ihose who had passed it, and I have obtained, as a ; cneral result, that
between the larynx and the glottis of a child of three or of twelve, the

424

difference of size is very inconsiderable, and cannot be estimated by the
height of the figure :—

That, at the epoch of puberty, the organ of the voice enlarges rapidly,
and that, in less than a year, the opening of the glottis increases, in the
propertion of five to ten, that its extent is thus doubled both in length and
breadth.

That these changes are less remarkable in women, whose glottis in-
creases, in the proportion only of about five to seven: that in this respect
they still resemble children, as the tone of their voices would lead us to
suppose.

These differences, in the size of the glottis, account for the danger which,
in children, accompanies the croup. For, suppose an opening of a line
and a half in width, of which the edges are covered with a membrane of
coagulable lymph, the opening will be entirely stopped : it would be only
narrowed, if its width were double: a sufficient space would remain free
from the passage of the air. This supposition, which I have employed to
make myself understood, is only the expression of the truth, since anato-
mical inspection shows that the glottis, in adults, is double the size it is
before puberty.

CCXX1X. Menstruation. The symptoms by which puberty is known,
in women, are not less remarkable. The swelling of the genital organs
straightens the opening of the canals that make part of them. The breasts
become enlarged, and form, at the fore part of the thorax, marked projec-
tions. Further, there comes on a discharge (apparently) of blood, which
takes place every month, from the vessels of the womb, and which is known
by the name of the menstrual discharge, or menses. This periodical eva-
cuation declares itself, in most women, by all the symptoms that indicate
fulness of blood, as spontaneous lassitude, heat, and flushings in theface;
and by others, which show the direction of the humours towards the
uterus, and a local plethora of that organ, as pains in the kidneys, and a
certain itching of the party. The first eruption puts an end to this state;
•which, in many, may be considered as real disease. A pure red blood
flows, in more or less abundance, for some days, the general heaviness
goes off, and the woman feeh herself relieved.

I shall not now speak of the many deviations incident to the menstrual
discharge, and which must be considered as real diseases. Thus, the
uterine discharge has been known to be supplied, by bleeding from the
nose, haemoptysis,melaena, and sometimes by unusual evacuations of blood
from the eyes, ears, the fore-finger, from ulcerated surfaces over different
parts of the body.

It is easily conceived, that the different parts of the sanguineous system
may supply each other's place, and that the bloody secretion, in which
menstruation consists, failing en the internal surface of the uterus, may
be carried on by another part equally provided with capillary vessels; but
that similar deviations may take place for the fluids secreted by the con-
glomerate glands, as urine, bile, saliva, is difficult to believe, notwith-
standing the many testimonies and authorities that may be brought in
support of this opinion.

The fluids are not in existence, before the work of secretion ; the urine,
retained in the bladder and in the uterus, the bile stopped in the gall
bladder and the hepatic ducts, after it hus been prepared by the peculiar
action of the liver, may, it is true, from absorption* by the lymphatic ves-
sels, be carried into the blood, and product there a diseased urinary or

bilious diathesis ; occasion an irritation and derangement, after which, the
humour of the cutaneous perspiration, and of the sweat, and the saliva
itself, will exhibit some of the qualities of the humour retained, and in-
troduced by the absorbents, into the circulation. The blood, contami-
nated by the admixture of a certain quantity of urine, may purify itself by
various emumctories, by urinous vomitings and sweats; but that urine
may, like the menstrual blood, come out at the eyes, theearsorthe navel,
except in case of urinary umbilical fistula; that one whose urinary dis-
charge, by the urethra, is not interrupted, may spontaneously vomit it, is
what no man, who has any sound notions of physiology, will believe; and
yet it is related, with full details, in a late work, where these errors are
found, in the midst of many interesting researches, on various points of
physiological chemistry. I have seen myself the woman, whose urine
has been so well analysed by Dr. Nysten, when the clinical professor of
medicine, at Paris, obliged her to submit to a severe but necessary exa-
mination, and I am astonished that well informed men should so long;
have given credit to such gross impostures. The reader will, I hope,
excuse this- long digression, for the sake of its importance. Literary
criticism is now carried on with such partiality, that no journalist, in
praising justly what is praise-worthy in the valuable work of Dr. Nysten,
has pointed out the imposture of which he was the dupe.

At first irregular, the menstrdal discharge assumes regularity, is re-
peated every month, and lasts from two days to a week, with evacuation
of from three ounces to a pound of fluid, every time. Women of san-
guine temperament, robust and libidinous, are those whose menses last
longest, and flow most copiously. The fluid is of an arterial red, and has
not, in a healthy woman, any of the pernicious qualities which have been
ascribed to it.

During the whole time of menstruation, women are weaker, more deli-
cate, more susceptible of impressions; all their organs partake, more or
less, in the affection of the uterus; and it L'not difficult to an observer.
of any practice, to discern, the state, not merely by the state of the pulse,
but by the change ofv countenance and tone of the voice. Women then
require very careful management. An improper blood-letting, a purge,
or any other remedy untimely administered, may suppress the discharge,
and occasion the most serious affections. Climate evidently influences
the duration and quantity of the discharge, since in Africa, it flows al-
most continually, whilst in Lapland, it takes place only two or three times
a year.

I shall not dwell upon the different explanations that have been given
of this phenomenon. Some have ascribed it to the oblique position of
the uterus, without considering, that upon their principal, menstruation
should take place from the soles of the feet. Dr. R. Mead believed
that it depended on the influence of the. moon over the female system ;
but why is it not then subjected to the lunar phases ? Those who have
found the cause of it in plethora, general or local, if we admit their
explanation, only changed the difficulty; for then, we must ask, what are
the causes of this plethora? But, if this opinion had any ground, ner-
vous women, with a small quantity of blood in their system, ought not
to menstruate ; and yet they do so plentifully. Must we ascribe menstrua-
tion to an acquired hubit ?

Is the problem resolved, by saying that all the secretory organs of wo-
men are too weak to evacuate the superfluitv of fluids, which would

486

require for them a new emunctory ? Bat is not this taking the effect for
the cause ? Does not this smaller quantity of fluids, proceeding from the
blood, arise from the purification which the blood undergoes in the ute-
rus ? Let it be remarked, in the mean time, that this periodical discharge
seems to exempt the sex from many inconveniences, from which our's
suffers ; such as gout, stone and gravel, so unfrequent with them, and so
common with us. Nor con we avoid recognizing, in this discharge, a
utility relative to conception; does it not seem to dispose the uterus to
that function*? (CCIV.) - Was it not requisite that this organ should be
accustomed to receive a great quantity of blood, that pregnancy, which
calls for this afflux, might not be injured, by bringing on a sudden cahnge
in the system, and the whole of the vital functions.

Menstruation is suspended during pregnancy: it is so during the first
month of suckling ; though this rule admits of many exceptions. Its
cessation, in our climate, is from the fortieth to the fiftieth year £ some-
times before, seldom later; though 1 have now before me the instance of
a woman of seventy, who has not yet ceased jto menstruate; a fact, which,
after all, is nothing more surprising, than that of menstruation beginning
at an early period of life. When menstruation ceases, the breasts col-
lapse, plumpness goes off, and the skin shrivels, and loses its softness,
colour, and suppleness. This cessation is the cause of a great many dis-
eases which break out, at this season of life, called the turn of life, and
are fatal to many women; but then, it is observed, that when this period
is past, their life is more secure, with more hope of prolonging it than a
man has, at the same age.

CCXXX. Of manhood. To youth succeeds manhood : which may
be considered as beginning from the twenty-first to the twenty-fifth year.
Then, all increase of the body, in height, is at an end. The processes
are completely united to the body of the bones; but still, growth goes on
in other dimensions. All the organs acquire remarkable hardness, so-
lidity, and consistency. It Is the same with the intellectual and moral fa-
culties. To the empire of imagination, succeeds that of judgment.
Man is capable of fulfilling all the duties of family and society. This
period of life, to which we give the name of mature age, extends to the
fiftieth or fifty-fifth year for men: it scarcely goes beyond the forty-fifth
for women, with whom it begins also a little sooner. During this long
interval, men enjoy the whole plentitude of their existence.

Although, in general, it is not difficult to distinguish, at first sight,
a man of twenty-five, from one of fifty, the differences which mark them,
depending on the quantity and colour of their hair, and on their muscu-
lar strength, are neither many nor very essential.

Let us avail ourselves of this age, during which the characters of the
human species, merely sketched, in childhood and youth, take a more
defined and lasting form, to trace the features of individuals and of
races.

CCXXXL Of temperaments and idiosyncrasies. We give the name
of temperaments to certain moral and physical differences in men, which
depend on the various proportions and relations among the parts that make
up their organization, as well as upon different degrees, in the relative

* The greater part of the female quadrupeds have the parts of generation batbetl in
a reddish Jymph, during1 the time of being" in heat. — Author's JVotev

427

energy of certain organs, "there is> besides, in each individual, a mode
of existence which distinguishes his temperament from that of any other,
to whom, howe.ver, he may bear great resemblance. We express by the
term idiosyncrasy^ these individual temperaments, the knowledge of which
is of no small importance in the practice of medicine.

The predominance of any particular system of organs, modifies the
whole economy, impresses striking differences on the results or the or-
ganization, and has no less influence on the moral and intellectual, than
on the physical faculties. This predominance establishes the tempera-
ment; it is the cause, and constitutes its essence.

If the heart and the vessels which carry the blood through every part,
are of predominant activity, the pulse will be sharp, frequent, regular, the
complexion ruddy, the countenance animated, the shape good, the forms
softened though distinct,: the flesh of tolerable consistence, moderate
plumpness, the hair fair and inclining to chesnut ; the nervous suscepti-
bility will be lively, and attended with rapid successfully, that is to say.
that being easily affected by the impressions of outward objects, men of
this temperament will pass rapidly from one idea to another; conception
will be quick, memory prompt, the imagination lively; they will be ad-
dicted to the pleasures of the table and of love ; will enjoy a health sel-
dom interrupted by disease 5 and all their diseases, and these slight, mo-
dified by the temperament, will have their seat principally in the circula-
tory system, (inflammatory fever, or angeiotenic ; jihlegmasia ; acute hx-
morrhage) and will terminate, when moderate, by the mere force of nature,
and require the use of the remedies, called antiphlogistic, among which,
bleeding is the chief. The ancients applied the name of sanguine to this
disposition of body; they considered it as produced by the combination
of warmth and moisture, and had very correctly perceived that it existed
in the young of both sexes, was heightened by the spring, the season
which has been justly compared to youth, calling that age the spring
time of life.

That the specific characters of the temperament I have just described,
may show themselves, in all their truth, it is requisite that the moderated
developement of the lymphatic system, coincide with the energy of the
sanguineous system, so that these tv/o sets of vascular organs may be in
true equipoise. The physical traits of this temperament are to be found
in the statutes of Andnous and the Apollo of Belvidere. Its moral phy-
siognomy is drawn in the lives of Mark Antony and Alcibiades. In Bac-
chus are found both the forms and the character. But why seek amongst
the illustrious men of antiquity, or among its gods, the model of the
temperament I have been describing, whilst it is so easy to find it among
the moderns ? No one in my opinion, exhibits a more perfect type of it
than the Marshal Duke of Richelieu, that man, so amiable, fortunate and
brave in war, light and inconstant, to the end of his long and brilliant
career*.

Inconstancy and levity are in fact, the chief attribute of men of this
temperament : excessive variety appears to be, to them, a necessity as

* See his Memoirs, 6 vols. 8vo..

Voltaire has painted his character, with superior ability, in many verses addressed to
him.

Rival du conquerant de 1'Inde,

Tu bois tu plais, tu combats, &c. Author's Note,

428

much as an enjoyment: good, generous, feeling, quick, impassionate, de-
licate in love, but fickle, disgust in them follows close upon enjoyment:
meditating desertion, in the midst of the most intoxicating caresses, they
make their escape from beauty, at the very moment she thought to have
bound them by indissoluble chains*. In vain he whom nature has endow-
ed with a sanguine temperament, will think to renounce the pleasures of
the senses, to take fixed and lasting likings, to attain, by profound medi-
tation, to the most abstract truths; mastered by physical dispositions, he
will be for ever driven back to the pleasures from which he flies, to the
inconstancy which is his lot; more fitted to the brilliant productions of
^vit, than the sublime conceptions of geniusf. His blood, which a vast
lung impregnates, plentifully, with atmospherical oxygen, flows freely in
very dilatable canals, and this facility in the distribution and course of
the fluid is, at once the cause and the image of the happy disposition
of his mind.

CCXXXU. If men of this temperament apply themselves, from cir-
cumstances, to labours which greatly exert the organs of motion, the
muscles, plentifully supplied with nourishment, and disposed to acquire
a developement proportioned to that of the sanguineous system, in-
creases in bulk: the sanguineous temperament undergoes a great modi-
fication; and there results from it, the muscular or athletic temperament,
conspicuous by all the Outward signs of vigour and strength. The head
is very small, the neck sunk, especially backward, the shoulders broad,
the chest large, the haunches solid, the intervals cf the muscles deeply
marked.

The hands, the feet,- the knees, all the articulations not covered by
mnscles, seem very small, the tendons are marked through the skin
which covers them : the susceptibility is not great : feeling dull and dif-
ficult to- rouse, the athletic surmounts all resistance, when he has broken
from his habitual tranquillity. The Farnese Hercules exhibits the model
of the physical attributes of this particular constitution of body; and
what fabulous antiquity relates of the exploits of this demi-god, gives us
the idea of the moral dispositions that accompany it. In the history of
his twelve labours, without calculation, without reflection, and as by in-
stinct, we see him courageous, because he is strong, seeking obstacles
to conquer them, certain of overwhelming whatever resists him; but join-
ing to such strength so little subtlety, that he is cheated by all the kings
he serves, and all the women he loves. It would be difficult to find, in
history, the example of a man who has combined, with the physical

* The history of Henry IV. of Louis XIV. of Regnard, and of Miraberui, proves that,
to the extreme love of pleasure, sanguine men join, when circumstances require it,
great elevation of thought and character; and can bring into action the highest talents
In every department.

•f- 1 have just met, in a gazette, with an assertion, at least singular. All the world
knows, says the journalist, that Newton was sanguine, and this proves clearly, he adds,
that temperaments have no influence on the intellectual powers. I would ask the jour-
nalist, where he has discovered that Newton \va.s sanguine. The few details which bio-
graphers have preserved on the physical temperament of this illustrious philosopher,
lead us to believe that his temperament was the melancholic, which is very frequently
met with in England. I will not dare to pronounce absolutely, on subjects on which we
can attain only a certain degree-of probability ; but if Newton had been sanguine, he
would not have gone to the grave at the age of fourscore, never having1 known woman,
as it is afhrmed lie did. — Author's Note.

429

powers which this temperament implies, distinguished strength of the
intellectual faculties. For excelling in the fine arts, and in the sciences,
there is need of exquisite sensibility, a condition absolutely at variance
with much developement of the muscular masses.

CCXXXIII. If sensibility, which is vivid and easily excited, can dwell
long- upon one object: if the pulse is strong, hard, and frequent, the sub-
cutaneous veins prominent, the skin of a brown* inclining towards yel-
low, the hair black, moderate fulness of flesh, but firm, the muscles mark-
ed, the forms harshly expressed ; the passions will be violent, the move-
ments of the soul ofteri abrupt and impetuous, the character firm and
inflexible. Bold in the conception of a project, constant and indefatig-
able in its execution, it is among men of this temperament we find those
who in different ages have governed the destinies of the world : full of
courage, of boldness, and activity, all have signalized themselves by great
virtues, or great crimes, have been the terror or admiration of the
universe. Such were Alexander and Julius Caesar, Brutus, Mahomet,
Charles XII. the Czar Peter, Cromwell, Sixtus V. Cardinal Richelieu,
and Napoleon the Great.

As love in the sanguine, ambition is in the bilious the governing pas-
sion. Observe a man, who, born of an obscure family, long vegetates in
the lower ranks : great shocks agitate and overthrow empires : at first a
secondary actor in these great revolutions which are to change his des-
tiny, the ambitious man hides his designs from all, and by degrees, raises
himself to the sovereign power, employing, to preserve it, the same ad-
dress with which he possessed himself of it. This is, in two words, the
history of Cromwell and of all usurpers*.

To attain to results of such importance, the profoundest dissimulation
and the most obstinate constancy, are equally necesssary ; these are,
further, the most eminent qualities of the bilious. No one ever combin-
ed them in higher perfection than that famous Pope, who slowly travel-
ling on towards the pontificate, went for twenty years, stooping and talk-
ing, for ever, of his approaching death, and who, at once, proudly rear-
ing himself, cries out, " I am Popef !" petrifying with astonishment and
mortification, those \vhom this artifice had deceived into his party.

Such too was Cardinal Richelieu, who raised himself to a rank so near
to the highest, and was able to maintain himself in it: feared by a King
whose authority he established, hated by the great, whose power he de-
stroyed, haughty and implacable towards his enemies, ambitious of every
sort of glory, &cj .

The historians of the time inform us, that this celebrated minister
showed all the customary signs of the bilious temperament. Gourvillc
tells us that he was, all his life subject to a very troublesome haemorrhoi-
dal discharge§.

This temperament is further characterized by the premature develope-
ment of the moral faculties. Scarcely past their youth, the men I have
named projected and carried into execution enterprizes which would have
been sufficient for their fame. An excessive developement of the liver, a

Vie d'OHvicr CiY>m\vcIl, par Jeuoy Dugour, 2 vols. 18mo.
y Vie tie Sixte Q-uintt 2 vols. in 12mo.

± See his character drawn, with as much truth as eloquence, by Thomas, in the last
edition of his Es»ai sur les Eloges.
§ Memoirs de Gourvjlle-

436

remarkable superabundance of the biliary juices, most commonly acconr-
pany ing this constitution of body, in which the vascular sanguineous system
enjoys the greatest, energy to the prejudice of the cellular and lymphatic
system, the ancients gave it the name of bilious. The diseases to which
those distinguished by it are subject, involve, in fact, either as their prin-
cipal characteristic, or as accessary circumstances, or as complication,
the derangement of the action of the hepatic organs, joined to changes
of composition in the bile. Among the remedies directed against these
sort of diseases, evacuants, and especially emetics, are the best.

Tf all the characteristics assigned to the bilious temperament are car-
ried to the highest degree of intensity, and to this state is added great
susceptibility, men are irascible, impetuous, violent, on the slightest oc-
casions. Such Homer describes Achilles, and some others of his
heroes.

CCXXX1V. When, to the bilious temperament, is added diseased
obstruction of any one of the organs of the abdomen, or derangement of
the functions of the nervous system, so that the vhal functions are feebly
or irregularly performed, the skin takes a deeper hue, the look becomes
uneasy and gloomy, the bowels sluggish, all the excretions difficult ;
the pulse hard and habitually contracted. The general uneasiness
affects the mind ; the imagination becomes gloomy, the disposition sus-
picious; the exceedingly multiplied varieties of this temperament called
by the ancients the melancholic^ the diversity of accidents that may bring it
on, such as hereditary disease? long grief, excessive study, the abuse of
pleasures, &c. justify the opinion which Glerc has proposed, in his natural
history of man, in a state qf disease, where he considers, the melancholic
temperament less as a primitive and natural constitution, than as a dis-
eased affection hereditary or acquired. The characters of Lewis XL and
Tiberius, leave nothing wanting for the moral determination of this tem-
perament. Read, in the Memoirs of Philip de Commines, and in the
Annals of Tacitus, the history of these two tyrants, fearful, perfidious,
mistrustful, suspicious, seeking solitude by instinct, and polluting it by all
the acts of the most savage atrocity, and the most ungoverned debauch.
Distrust and fearfulness, joined to all the disorders of imagination, com-
pose the moral character of this temperament. The passage in which
Tacitus paints the artful conduct of Tiberius, when he refuses the em-
pire, offered him, after the death of Augustus, may be given as the most
perfect model of it. Fersse inde ad Tiberiem p. reces, fyc. Corn. Tacit. An-
nal. lib. I.

As Professor Pinel very justly observes, in his treatise on insanity, the
history of men celebrated in the sciences, letters and arts, has shown us
the melancholic under a different light : endowed with exquisite feeling,
and the finest perception : devoured with an ardent enthusiasm for the
beautiful, capable of realizing it in rich conceptions, living with men in
a state of reserve bordering upon distrust, analyzing with care all their
actions, catching in sentiment its most delicate shades, but ready in un-
favourable interpretations, and seeing all things through the dingy glass
of melancholy.

It is extremely difficult to delineate this temperament in a general or
abstract manner. Though the ground-work of the picture remains al-
ways the same, its numerous circumstances give room for an infinite
number of variations. It is better, therefore, to have recourse to the lives
©f illustrious men, who have exhibited it in all its force. Tasso, Pascal,

3T. J. Rousseau, Gilbert, Zimmerman, are remarkable, among many others,
and deserve, by their just celebrity, to fix our consideration. The first,
born in the happy climate of Italy, proscribed and unhappy from his child-
hood, author, at twenty-two years old, of the finest epic poem the moderns
can boast of, seized in the midst of the enjoyments of premature glory,
with the most violent and most inauspicious love for the sister of the Duke
of Ferrara, at whose court he lived : an extravagant passion, which was
the pretext of the most cruel persecutions, and which followed him to
his death; this took place towards the thirty-second year of his age,
on the eve of a triumphal pomp which was prepared for him in the
capitol.

The author of the Provincial Letters, and of the Thoughts, enjoying,
like Tasso, a premature eelebrity, almost on quitting childhood, was
led to melancholy, not like him by the crosses of unhappy love, but, by a
violent and overpowering terror, which left, in his imagination, the sight
of a gulph for ever open at his side ; an illusion which left him only at
his death, eight years after the accident*.

No one perhaps, has ever shown the melancholic temperament, in a
higher degree of energy, than the philosopher of Geneva. To be con-
vinced of it, it is enough to read, with attention, certain passages of his
immortal works, and especially the two last parts of his confessions, and
the Reveries in the solitary walker : tormented with continual distrusts,
and fears, his fruitful imagination represents to him all men as enemies.
If you believe him, the whole human race is in league to do him mischief,
u kings and nations have consfiired together against the son of a jwor watch-
maker ;" children and invalids are brought in to execute these dreadful
plots. But let us leave him to speak for himself, the most eloquent
and most unfortunate man of the eighteenth century : u Here then I am,
alone upon the earth, without brother, neighbour, friend, without society
but myself ; the most sociable and the most loving of men has been pro-
scribed by them with unanimous consent. " Further on he adds, "Could
J believe that I should be held, without the smallest doubt, for a mon-
ster, a prisoner, an assassin, that I should become the horror of the hu-
man'race, and the game of the rabble ; that all the salutation of those that
passed by me, would be to spit upon me 5 that a whole generation would
amuse itself, with unanimous consent, in burying me alive ?" It is idle
to multiply quotations, in speaking of the works of a philosopher, who,
in spite of his errors, will ever be the delight of all those who love to
read and to thinkf.

The history of J. J. Rousseau, like that of all the melancholies who
have distinguished themselves in literature, shows us genius struggling
with misfortune ; a strong soul lodged in a feeble body, at first gentle,
affectionate, open and tender, soured by the sense of an unhappy condi-
tion, and of the injustice of men. Till the time when, impelled by the
desire of fame, Rousseau sprang forward in the career of letters, we see
him endowed with a sanguine temperament, acting with all the qualities
belonging to it, gentle, loving, generous, feeling, though inconstant : his
fertile imagination shows him nothing but gay images, and, in this illu-

* Blaise Pascal died at 89. See his life by Condorcet.

f Consult the Studies of Nature, by Betnardin de Saint Pierre ; and the Letters on
J. J. Rousseau, by Madame de Stael.

sion of happiness^ he lives on agreeable chimeras; but gradually uncle*
ceived byjthe hard lessons of experience, afflicted, in the depth of his
heart, witfi his own wretchedness and the wrongs of his fellow-creatures,
• his bodily vigour wastes and decays, with it his moral nature changes,
and he may be referred to as the most striking proof of the reciprocal in-
fluence of the moral on the physical, and the physical on the moral part
of our being*. His history is a proof, beyond reply, that the melancholic
temperament is less a peculiar constitution of the body than a real dis-
ease, of which the degrees may infinitely vary, from a mere originality
of character, to the most decided munia.

Gilbert arrived at Paris, with the germs of talents fitted for that great
theatre. Poor and rebuffed by those on whom he had built his hopes, he
mixed in the ranks of their detractors, and soon signalized himself,
among the most formidable, by a vigour worthy of a better cause. Per-
secuted, without respite, by want ; the mortifying sight of the happiness
which his enemies enjoyed, and to which he believed himself called, led
him on to a state of perfect madness. He believed himself persecuted by
the philosophers, who wanted to rob him of his papers : to save them
from the imagined rapacity, he locked his manuscripts in a press, and
swallowed the key. It stuck at the entrance of the larynx, stopped
the passage of the air, and suffocated the patient, who died, at the Hotel-
Dieu, after three days of the most cruel sufferingsf.

Zimmerman, early exhausted by study, already a physician of celebrity,
at an early age, lived in solitude, with an ardent imagination joined to
the highest susceptibility? abandoned to himself, devoured with the thirst
of glory, he gave himself up to labour in excess, published his treatise on

* I have no doubt that the influence of the physical organization on the intellectual
faculties is so decided, that we may regard .as possible the solution of the following
problem, analogous to that with which Condillae concludes his work on the origin of
human knowledge.

The physical man being given, to determine the character and extent of his capacity, and
to assign, consequently: not only the talents he possesses, but those he is capable of acquiring,

The profound meditation of the work of Galen (guodanimi mores corporis temper amenta
seqnantur ,•) the perusal of Plutarch's Lives of Illustrious Men, and of the other biogra-
phers and historians of ancient and modern times; of the Eulogies of Fontenelie, Tho-
mas, d'Alembert, Condorcet, Vicq-d'Axyr, Sec. and the study of the medico-philosophi-
cal works of Haller, Cullen, Cabanis, Pinel, Halle, who have modified and enriched the
ancient doctrine of temperaments, will be of great avail in the search of this solution.
" Philosophy," cries an eloquent writer, in the noble enthusiasm which seizes him at
the sight of the riches accumulated by Fontana, in the Anatomical Museum in Florence,
** Philosophy has been in the wrong, not to descend more deeply into physical man ;
there it is that the moral man lies concealed; the outward man is only the shell of the
man within. — (Dupaty, 33cl Letter on Italy — Author's Note.

•j- His life would have been preserved, if the cause of his illness had been understood,
which he indicated himself by repeating frequently " the key chokes me." His state of
madness made this pass for the words of a madman; but on opening the body, they key
Mras found, of which the ward was fixed at the entrance of the larynx : it would have
been easy, to draw it out, by putting a finger down the throat.

This unfortunate young man expressed, a few days before his death, the melancholy
state of his soul, in stanzas most touchingly mournful : this is one, full of interest and
simplicity :

Au banquet de la vie infortune convive,

J'apparus un jour, et je meurs :
Je meurs et sur ma tombe oulenteinent j'arrivc

Nul ne viendra verser cles pleurs. Jluitiv's Note.

433

Experience, and the work on Solitude, so deeply imbued with the
colouring of his soul. Forced from the solitude he loved, he carried,
into the courts to which his reputation called him, in an exhaustible store
of bitterness and sadness, which political events supervening brought to
greater excess : arrived, at length, gradually at the last term of hypo-
chondria* he died beset with pusillanimous fears, worthy of all eulogium
and all regret*.

CCXXXV. If the proportion of the fluids to the solids is too great,
this superabundance of the humours, which is constantly in favour of the
lymphatic system, gives to the whole body considerable bulk, determined
by the developement and repletion of the cellular tissue. The flesh is
soft, the countenance pale, the hair fair, the pulse weak, slow, and soft,
the forms rounded and without expression, all the vital actions more or
less languid, the memory treacherous the attention not continuous. Men
of this temperament, to which the ancients gave the name of pituitous,
and which we should call lymfihatic,, because it depends really on the ex-
cessive developement of this system, have, in general, an insurmountable
inclination to sloth, averse like to labours of the mind and body : accord-
ingly, we are not to wonder, if we find none of them among Plutarch's
Illustrious Men. Little fitted for business, they have never exercised
great empire over their fellow-creatures, they have never changed the
face of the globe, by their negotiations or their conquests. One of the
friends of Cicero, Pomponius Atticus, whose history Cornelius Nepos
has left us, conciliating to himself all the factions- which tore the Roman
republic to pieces, in the civil wars of Caesar and Pompey may be given
as the model of it. — Among the moderns, the easy Michel Montaigne,
all whose passions were so moderate, who reasoned on every thing, even
on feeling, was truly pituitous. But, in him, the predominance of the
lymphatic system was not carried so far, but that he joined it to a good
deal of nervous susceptibility. In the pituitous, from the excess of wa-
tery particles in the fluid which should carry every where heat and life,
the circulation goes on slowly, the imagination is weak, the passions
languid; and, from this moderation of the desires, spring, on many occa-
sions, those virtues of temperament, which, to say it, by the bye, should
not supply their possessors with matter of quite so much self-com-
placency.

CCXXXVI. This property by which we are, more or less, sensible
to impressions on our organs, weak in the pituitous, almost nothing in
athletes, moderate in those of sanguine temperament, rather quick in the
billious, constitutes, by excess, nervous temperament; — seldom natural
or primitive, but commonly acquired, and depending on a sedentary and
too inactive life, on habitual indulgence in sensuality, on a morbid action
of the brain promoted by reading works of imagination, 8cc. This tem-
perament shows itself in the emaciation, in the smallness of the muscles,
soft, and, as it were, in an atrophy, in the vivacity of the sensations, in
the suddenness and mutability of the determinations and judgments.—
Nervous women, whose wills are absolute but changeable, with excess of

* See his Eulogium by Tissot ; it is at the beginning of the last edition of the Treatise
on Experience in Medicine. It there appears how deeply he was affected by the French
revolution, of which he foresaw, with a sort of prophetic spirit, the disastrous conse-
quences to his own country.— Author's Note.

3 I

434

sensibility, frequently exhibit it with all these characteristics. Often?
however, they have something of good looks, the extreme preponderance
of the nervous system still allowing a moderate developement of the lym-
phatic. Spasmodic affections are not uncommon among them ; and
when it is observed that, on the other hand, the athletic constitution, di-
rectly opposite to the nervous temperament, predisposes to tetanus, may
we not say, that the two extremes meet, or produce the same effects?

Anti-spasmodics are employed, with success, in the treatment of their
diseases, which partake always, more or less, of the temperament. Sti-
mulants, on the contrary, are very suitable to those of pituitous or lym-
phatic temperament. The nervous temperament, like the melancholic,
is not so much a natural constitution of the body, as the first stage of a
disease. This temperament, like the nervous affections which are the
result of it, has never shown itself but among societies brought to that
state of civilization, in which man is th€ farthest possible from nature.
The Roman ladies became subject to neivous affections, only in conse-
quence of those depraved manners which marked the decline of the Em-
pire. These affections were extremely common in France, during the
eighteenth century, and in the times preceding the fall of the monarchy.
Of that epoch, are the works of Whytt, Raulin, Lorry, Pomme, &c. on"
nervous affections. — Tronchin, a Genevese physician acquired great
wealth and reputation by the treatment of these diseases. His whole se-
cret consisted in exercising to fatigue, women habitually inactive, keep-
ing up their strength, at the same time, by simple, healthy, and plentiful
food. The two most remarkable men of the eighteenth century, Vol-
taire and the great Frederick, may be given as instances of the nervous
temperament; and the history of their brilliant and agitated life, shows,
sufficiently, how much the circumstances in which they lived, contribu-
ted to develope their native dispositions.

I shall finish this article on temperaments by observing, that in truth,
we bring with us into the world these particular dispositions of body: but
that from education, manner of life, climate, acquired habits, they are
altered, ov altogether changed. Further, it is exceedingly rare to find
individuals, who show, in their purity, the characters assigned to the
different temperaments: the descriptions given are drawn from an as-
semblage of individuals, much resembling one another. Their charac-
ters are pure abstractions, which it is difficult to realize, because all men
are at once sanguine and bilious, sanguine and lymphatic, Sec. In this
instance, physiologists have imitated the artist, who united in Che image
of the goddess of beauty, a thousand perfections which he saw separate
in- the most beautiful women of Greece*.

It is an observation that the sanguine constitution is directly opposed
to the melancholic, and never combines with it ; that it is the same with
the bilious and lymphatic : though it may happen that a man sanguine
in youth, shall become melancholic after a lapse of time : for, as I have
said before, man never remains such as he came from the hands of Na-
ture ; fashioned by all that surrounds him, his physical qualities, at dif-
ferent periods of his life, are as much changed as his character.

* It is thus that, in the arts of imitation, the ideal grows up ; now, from the exaggera-
tion of features, now, from the union of qualities which Nature has produced separate. —

435

Of all the causes that can modify the nature of man, and which will
even change completely the nature of his native dispositions, there is
none more powerful than the long continued action of air, water, and re-
sidence, as the father of medicine has said. Climate, in fact, exerts upon
the temperament the most marked influence. Thus the bilious tem-
perament is that of the greater part of the inhabitants of southern
countries; the sanguine that of the north; the lymphatic constitution
reigns, on the contrary, in cold and moist countries, like Holland. We
have seen in what manner the athletic, melancholic, and nervous tern-
temperament grows out of our habits of life : let us now endeavour to
appreciate the power of climate over the constitution of the greater part
of mankind.

It is known, that the influence of heat, in the production of bilious
diseases, is such, that after having been extremely prevalent, during the
summer, they disappear, or at least become much less frequent in the
autumn. A notable increase of perspiration never takes place, without
a proportional diminution in the quantity of the liquids with which the
alimentary surfaces are moistened. Now, when the gastric juice is less
abundant, the bile, being mixed with a smaller quantity of serosities, ir-
ritates more the intestinal surfaces; the digestive powers languish, and
there is an approaching disposition to meningo-gastric fevers. The
same influences, continued during the whole year in hot countries, must
necessarily increase, with the activity of the biliary system, its power
over the other parts of the economy, and thus establish a predominance
of the bilious constitution, through both health and disease.

As for the sanguine temperament, so generally met with among north-
ern nations, it is the necessary consequence of the continual and very en-
ergetic re-action of the powers of circulation, against the effects of exter-
nal cold. It is only by the constant activity of the heart and vessels, that
calorification can be effected with the necessary vigour. Now, the effects
of this redoubled action are the same to the organs of circulation, as to
the muscles under the influence of volition : in both, exertion increases
the power of the organs exerted. The diseases of the nations of the
north, analagous to their temperament, have, for the most part, their seat
in the system of sanguineous vessels : their character is eminently inflam-
matory.

Lastly, the lymphatic state of nations, living under a moist climate, is
nothing more surprising than the aqueous nature of plants, and small
density of the wood, in trees growing under the influence of a foggy air.
Animal bodies, like plants, absorb by their surfaces, and become gorged
with humours, the excess of which always produces a remarkable slack-
ening of activity in the organic motions.

The temperament of which the character is the predominance of one
organ or system of organs, departs from that ideal state, where all the
powers are reciprocally balanced, so as to exhibit in the living economy a
perfect equilibrium. This state, which has perhaps never been found
but in the imaginations of physiologists and which was called by the an-
cients the temperate temperament, temperamentum temperatum^ being'
taken as the type of health, it follows that this temperament is already a
step made towards disease. Yet the action of the predominant system is
not in such excess as to destroy all equilibrium, and impede the action of
life; but let the constitutional dispositions be much increased, the dis-
ease is begun, and this transition takes place in the conversion of the

lymphatic temperament into scrophula*. In the scropliulous constitu-
tion, there is, at once, activity of the absorbing mouths, great facility of
absorption, inertness of the vessels and lymphatic glands, weakness of the
absorbents, and consequently a thickening and stagnation of the liquids
absorbed. The same thing is seen in the lymphatic temperament, cha-
racterized by the activity of the inhaling mouths, and the debility of the
lymphatic system, as Professor Cabanis was awaref, when he refuted the
opinion of those who ascribe the lymphatic temperament to the excess of
activity in the absorbent system, though the only part of this system re-
ally quickened, is that which immediately performs absorption, whilst
the rest is in a state of perfect atony.

CCXXXVIL Varieties of the human species. The power of producing,
by copulation, individuals which are alike, is considered by naturalists as
the most certain test for fixing the species in red and warm-blooded ani-
mals. This power of self-perpetuation, by a constant succession of simi-
lar beings, is found in all the races composing the human species, how-
ever different in colour,. structure, and manner of life. Men, then, are
but one species, and the difference that appears in them, according to the
region of the globe they inhabit, can only constitute varietes or races. I
admit, with Mr. Lacepede, the worthy continuator of Buffbn four principal
races of the human species, which I shall call, like him, the European Arab,
the Mogul, the Negro, and the Hyperborean. We might add a fifth, of the
American, were it not most probable, that the new Continent is peopled
by inhabitants, who, coming from the old, either by land in the austral
hemisphere, or along the immense Archipelago of the Pacific Ocean,
have been altered by the influence of that climate, and the yet virgin soil,
so that they are to be regarded less as a distinct race than a simple va-
rietyj.

There is, in truth, this difference between varieties and races, that, in
these last, there are implied modifications more profound, more essential
differences, changes not confined to the surface, but extending to the very
structure of the body ; whereas, to make a variety, nothing more is need-
ed, than the superficial influence of climate on the integuments which it
colours, and on the hairs which it makes longer or shorter, lank or curl-
ed, hard or soft. An Abyssinian, scorched by the heat of an almost tro-
pical sky, is as black as the negro under the equator? yet they are by no
means of one race, since the Abyssinian, a negro only in colour, resem-
bles the European in the cast of his face, and the proportions of all his
parts.

The characteristics of the European Arab race, which takes in the in-
habitants, not of Europe only, but of Egypt also, Arabia, Syria, Barbary,
and Ethiopia, are an oval, or almost oval face, in the vertical direction, a
long nose, a prominent skull, long and commonly lank hair, a skin more
or less white. These fundamental characteristics are no where more
decided than in the north of Europe- The inhabitants of Sweden,
Finland, and Poland, give the prototype of the race: their .stature is tall,

* See Nosographie C/iirurgical, tome I. for the history of scrophulous ulcers, from
which this paragraph is taken entire. The author, in that work, has aimed at introdu-
cing1 physiology into surgery, till then exclusively abandoned to explanations of the
grossest mechanism. — Jiutho^s Note.

| Of the relations of the physical and moral man, by G. Cabanis, Senator, Professor
in the Scnool of Medicine in Paris, £.c.

* See APPENDIX, Note L L.

their skin of perfect whiteness, their hair long, lank, and of a light co-
lour of the iris generally bluish. The Russians, the English, the Danes,
the Germans, are already removed somewhat from this primordial type:
the colour of their skiu is of less pure white, their hair of a deeper hue.
The French seem to stand midway betwixt the nations of the north, and
those of the south of Europe. Their skin is shaded with a deeper dye,
their hair less straight, and more of a chesnut and brown colour. The
Spaniards, the Italians, the Greeks, the European Turks, and the Portu-
guese, are browner, their hair in general black. Lastly, the Arabs, the
Moors, and the Abyssinians have hair, in som-e measure, black and crisp,
the skin tawny, and might serve for the step from the European Arab to
the Negro race; which is, however, distinguished from them by the
flattening of the forehead, the smallrtess of the skull, the slope of the line
measuring the height of the face, the thickness of the lips, the projec-
tion of the rnalar bones, and further, by a darker skin, thicker, greasy,
and, as it were, oily, as well as by shorter, finer, curly, and wooly hair.

The Mogul race has the forehead flat, the skull jutting but little, the
eyes looking rather obliquely outwards; the cheeks are prominent, and
the oval of the face, instead of extending from the forehead to the chin,
is drawn between the two malar bones. The Chinese, the Tartars, the
inhabitants of the Peninsula, of the Ganges, and of the other countries
of India, of Tonquin, Cochin-China, Japan, of the kingdom of Siam,
&c. compose this race, which is more numerous than all the others, and
apparently more ancient also, which is spread over a greater extent of
Surface than the European Arab race, and yet greater than the Negro
race, since it reaches from the fortieth to the sixtieth parallel of latitude,
occupying an arc of the meridian of nearly 75°, whilst that which mea-
sures the countries of the European race is only of 50°, and the Negro
race lying under the equator, between the tropics of Cancer and of
Capricorn, is bounded within the limits of an arc of from 30° to
35°*.

The Hyperborean race, situated in the north of the two continents, in
the neighbourhood of the polar circles, composed of the Laplanders,
the Ostiaks, the Samoiedes, and the Greenlanders, is characterized by
a flat face, a squat body, and a very short stature. This degraded por-
tion of the human species derives, evidently, from the climate, its dis-
tinctive characteristics. Striving for ever with the inclemency of a se-
vere climate, the destructive action of an icy temperature, Nature, fet-
tered in her motions, shrunk in her dimensions, can produce only beings
whose physical imperfections explain their almost barbarous condition.

The small progress of the negroes in the study of the sciences, and
in civilization, their decided taste, and singular aptitude for all the arts
which require more taste and dexterity than understanding and reflec-
tion, as dancing, music, fencing, Sec. the figure of the head, which is
midway between that of the European and the ourang-outangf, the ex-

* Lacepede, Geographic Zoologique.

f The black colour of the skin in the negroes seems owing, as I have already said,
to the scorching- of the gelatine, which is the base of the rete mucosum of Malpighi.
This colour, acquired in a long succession of ages, perpetuated and transmitted by ge-
neration, is become one of the characteristic features of the Negro race. M. Volney,
in a work which should be a model to all travellers, grounds on the face of the blacks,
a conjecture as ingenious as it is probable. He observes, that it exhibits pre-

438

istence of the intermaxillary bones, at an age when, with us, the traces
of their separation are completely effaced ; the high situation and small
drvelopement of the calf of the leg, have been arguments more specious
than solid to those who have endeavoured to abase this portion of the
>*uman species, in order to justify an iniquitous traffic, and a cruel ty-
ranny; reproaches of civilized men, which they must wipe off by other
means than a presumptuous assertion of their own dignity, or a proud
insult on the native character of those whom they themselves have cast
into degradation.

Without admitting this belief, which owes its origin to a thirst of
riches, we cannot help acknowledging that the differences of organi-
zation draw after them' a striking inequality in the devclopement of the
moral and intellectual faculties. This truth would appear in its full
light, if, after summarily indicating, as I have just done, the physical
characteristics of the races of men, I could unfold their moral differences
as real, and not less marked: opposing the activity, the versatility, the
restlessness of the European, to the indolence, the phlegm, the patience
of the Asiatic, examining what is the power, or the character of nations,
the fertility of soil, serenity of sky, mildness of climate; showing by
what catenation of physical and moral causes, the empire of custom is
so powerful over the people of the east, that we find in India and China
the same laws, manners, and religion, which prevailed there long before
our era; inquiring by what singularity, well worthy the meditation of
philosophers and politicians, these laws, this worship, and these man-
ners, have undergone no change, amidst the revolutions which have so
often taken place among those nations many times conquered by the war-
like Tartars; showing how, by the irresistible ascendancy of wisdom and
knowledge, ignorant and ferocious conquerors have adopted the usages
of the nations they have subjugated; and proving that the stationary
condition of the sciences and arts among those who, so long before our-
selves, were in possession of the advantages of civilized society, is deri-
ved not so much from the imperfection of thier organization, as from the
degrading yoke of a religion loaded with absurd practices, and which
makes knowledge the exclusive birth-right of a privileged cast*. But
such an undertaking, besides exceeding the limits I have prescribed my-
self, does not belong directly to my subject.

The JHbinoes of Africa, the Cagots of the Pyrenees, and the Cretins of
the Valais, cannot be given as varieties of the human species. They

cisely that state of contraction which OUP face takes when it is struck by light, and a
strong1 reverberation of heat ; then, says this philosophical traveller, the brow contracts,
the cheek-bones rise, the eye-lids contract, and the lips project. Must not this contrac-
tion of the moveable part have influenced, in course of time, the hard parts, and even
moulded the structure of the bones ? Voyage en Syrie ct en Egyptt torn. I. p. 70. Sieme
Edition. — Jlnlhor's Note.

* \Ve must assign further as a main cause of the want of progress of the Indians and
Chinese, in the arts and sciences, sprung from civilization, the imperfection of their al-
phabet, which, being composed of a multitude of characters, which do not, like ours,
represent sounds, but ideas. It belongs not to our subject to show, how much signs
so defective must confine the sphere, and fetter the combinations of the mind.

See, concerning the religion of the Bramins, and the Indian customs, Raynal's Phi-
losophical History : the Asiatic Researches; Institutes of Menu, Edin. Review, xxxii. ;
Ward's View of "the History of the Hindoos : Halked's Code of Gentoo Laws ; Cole,
brook's Digest of Hindoo Law.

439

are infirm, feeble, degraded beings, incapable of re-producing an exist-
ence, which has fallen to them, in the midst of a healthy, vigorous, and
robust population.

We are not to believe what some travellers have written on the exis-
tence of tribes of giants, that have appeared on the Magellanic coast.
The Patagonians, concerning whose stature there is so little agreement
in relations, are men very well formed, and whose stature does not ex-
ceed ours more than nine or ten inches. The Laplanders, whose stature
is the smallest, are as much below, as the Patagonians are above ; it
does not exceed from four feet to four and a half. In the midst of our-
selves, individuals reach from time to time, a stature sufficient to entitle
them to the name of gaints, whilst others, shrunk in all their propor-
tions, are a renewal of the pymies. Such was Bebe, the dwarf of Stan-
islaus, king of Poland; Goliah, spoken of in the book of Kings, chap,
xvii. v. 4; the king Og, Deut. chap. iii. v. 2; and many others, whose
stature varies from six to ten feet high.

CCXXXVIII. Of old age and decrepitude. The human body, which,
from the twentieth year of life, ceases to grow in height, increases in
every dimension during the twenty succeeding years. After this period,
far from growing, it begins to decay, and loses daily a part of its strength.
The decay proceeds at the same rate as the growth, and is not more ra-
pid, since man requires from thirty to forty years in reaching to his full
growth, and takes about the same time in his progress to the grave, pro-
vided no accident hurries him to an untimely end*. The whole bulk of
the body diminishes!, the cellular tissue becomes collapsed, and the skin
wrinkled, especially that of the forehead and face. The hairs of the
head and over the rest of the body turns gray, then white; the organic
action becomes languid; the fluids become more disposed to putrefaction
(Hunter;) hence, at this period of life, all diseases of debility are more
frequent, and attended >with greater danger.

Decay succeeds old age. The sensibility of the organs is blunted; the
physical and intellectual faculties undergo a gradual decay; man ceases

* The duration of life may be estimated by that of the growth. A dog ceases to
grow at the end of two or three years, and lives only ten or twelve ; man, whose
growth requires a space of from twenty to thirty years, attains to the age of ninety or
a hundred. Fishes live several centuries, their developement requiring- a considerable
number of years — Author's Note.

•f- The diminution of the entire bulk of the body of aged persons frequently gives
place to an augmentation of size, especially of the trunk of the body. This is en-
tirely owing to the increased deposit of fat, which often supervenes at this age, and
which appears to depend on the energy of the system being insufficient to the com-
plete assimilation of the nutritive materials, and on the slow circulation of the blood in
the capillary vessels, which state of the circulation seems to give rise to the predomi-
nence of hydrogen and carbon in the blood which these vessels and the ve.ns contain.
The abundance of these elements in the extreme vessels being the source whence the
fat is so largely formed, the combination of them into that particular substance is the
result of the same state of the vital energies which favours their predominance. The
increase of bulk, owing to this augmentation of the secretion of fat, in persons ad-
vanced in life, is far from being favourable to the free exercise of the various functions ;
for certain organs being incommoded with the weight and bulk which they thus ac-
quire, are still further embarrassed in their organic movements, the circulation in the
extreme vessels is rendered still slower, and thus the cause of the increased secretion
of fat goes on increasing. This sufficiently accounts for the fact, that, in general, lean^
ness is at an advanced age more favourable to long life, than the opposite state,

440

to be impressed, in the same manner, by surrounding bodies. His judg-
ments are incorrect, because self-love preventing him from being aware
of the changes which he lias undergone, he is more disposed to ascribe
to a universal degeneracy, the difference which exists between the sensa-
tions which he now experiences,- and those which he experienced in his
youth, (laudator temporis acti.) The digestion is bad, the pulse weak
and slow; the absorption difficult, from the almost complete obliteration
of the lymphatics and the induration of the conglobate glands; the lan-
guid secretion and imperfect nutrition. The old man is slow in all his
actions, and stiff in all his motions; his hair falls off, his teeth drop from
their sockets; the cartilages ossify; the bones grow irregularly and be-
come anchylosed, their internal cavity enlarges; all the organs become
indurated, and the fibres dried and shrivelled. The bones become heavier,
from the gradual accumulation of phosphate of lime, and if those of the
skull, as is justly observed by Soemmering, on the contrary, become
lighter, it is that they are, in a manner, worn out.

The ossification of some of the cartilages, for example, those of the
ribs and vertebrae, is productive of remarkable effects. The ribs be-
coming soldered, in a manner, to the sternum, perform very imperfectly
their natural motion of elevation and twisting, (LXXI.) which produces
the enlargement of the chest. This cavity dilating1 less fully, the pulmo-
nary combinations, which are the abundant sources of animal heat, take
place in a less effectual manner, which, joined to a want of tone and
energy in the lungs, and in all the organs, lowers the temperature of old
people, as was observed by the father of physic*, a circumstance, how-
ever, which has been denied by Dehaen.

Those fibre-cartilaginous lamina, -with oblique fibres crossing each
other, which unite so firmly the bodies of the vertebrae, become indu-
rated, dried, and shrivelled, sink under the weight of the body, and do
not recover their former thickness, so that the stature is really reduced ;
besides, the weakened condition of the muscles which raise the trunk,
makes the weight of the viscera bend forward the vertebral column,
whose different parts may remain fixed in this attitude, so that the whole
column, consisting of twenty-four vertebrae, may come to consist of
only seven or eight distinct bones. It should not be imagined, however,
that all the soft parts become more compact, for several, as Haller ob-
serves, the muscles, for instance, become softerf, and seem, in losing
a part of their vital properties, to draw towards a speedy dissolution;
not that death is entirely owing to the accumulation of phosphate of
lime, which enters into the composition of all the organs, converts into
ossific matter the whole osseous system, and interrupts the action of the
animal machine. If this ossific matter invade every part of the animal
system, it is because the digestive powers, gradually weakened, cease to
affect, in a suitable manner, the alimentary substances. The exuberance
of calcareous salts, is, therefore, not so much the cause as the effect of
the successive destruction of the vital powers.

* Senibus autem jpodicus est calor * * * * f rigidum est enim ipsorum corpus. Hip-
pocr. Aph. 14. Sect. 2.

f Non ergo in sola rigiditate causam senum mortis oportet ponere ; nam ex defectu
irritahiiitatiSj plurimi in senibus musculi languent, mollesque pendent.

ElementaPhvsiol. torn. VIII. 4to. lib. 30.

441

The slowness, the rigidity, and the difficulty of moving, do not depend
so much as is thought, on the induration of the ligaments and other
fibrous organs : these ligaments become softened and relaxed to a con-
siderable degree, so that luxation is more easily performed, after death,
in old people. In them, likewise, organs, which, in youth, have a de-
gree of consistency, become flaccid and soft: this is the case with the
heart, which becomes collapsed in old people, its cavities remaining en-
tire, while in young persons, and in adults, their parietes are not in close
contact.

The brain becomes harder and firmer, less soluble in alkalies; its
albumen appears more completely oxydized than in younger subjects :
impressions are less easily made, and the motions necessary to the ope-
rations of the understanding are performed with difficulty. Hence, in
decrepitude, man returns, as far as relates to his intellectual faculties, to
a state of second childhood, limited to certain recollections, which are
at first confused, and, in the end, completely lost, incapable of judgment
or will, or of new impressions ; sleep resumes its influence ; reduced to
a mere vegetative existence, he sleeps the greatest part of the day, and
wakens only to satisfy his physical wants, and to take food, which he
digests very imperfectly; for, in the first place, the want of teeth pre-
vents his being able to divide sufficiently the different substances, and iu
the next place, the supply of saliva, of gastric and intestinal juices, is al-
most interrupted ; the bile and other fluids are less active, and the intes-
tinal tube is without energy. Universal rigidity will be admitted as one
of the principal causes of death, if it be considered that women, in whom,
the organs are naturally softer, are longer in reaching that state^ are more
retentive of life than men, and generally live to a greater age.

The body, therefore, dies slowly, and by degrees, says the eloquent
De Buffon ; life gradually becomes extinguished, and death is but the
last term of this series of degrees, the last shade of life.

CCXXXIX. Of Death, Long, in fact, before the close of life, man
loses the power of reproduction ; and, in the course of the agony which
serves as a passage between life and death, the organs of sense first be-
come insensible to all sorts of impressions ; the eyes grow dim, the cor-
nea fades, the eye-lids close, the voice becomes extinct, the limbs and the
trunk motionless 5 yet the circulation and respiration continue to be car-
ried on, but at least cease, first in the vessels farthest from the heart, and
then gradually in the vessels nearest that organ. Respiration, gradually
slackened, being entirely suspended after a strong expiration*, the lungs
no longer transmit the blood\vhich the veins bring from every quarter
to the heart. This fluid stagnates in the right cavities of the heart, and
these die last, (ultimum moriens) and distended by the blood which col-
lects within them, they attain a capacity exceeding greatly that of the
left cavities, which are, to a certain degree, emptied.

* Noii ergo in sola rigiditate causam senmin mortis opertet poncre ; nara ex defect'1,
irritabilitatis, plurimi in senibus musculi languent, mollesque pendent.

Elementa Physiol. torn. VIII, 4to. lib. 30.

f Does this last and powerful expiration, often attended by sighing, depend on the
spasmodic contraction of the muscles of expiration ; or rather does it not depend on the
re-action of the elastic pails which form the chest, a re-action which suddenly cease0
tp be counterbalanced by the vital properties ?~.rfuthQr's Note,

3K

442

Such is the course of natural death; the brain ceases to receive
the weakened heart, a sufficient quantity of blood to keep up sensibility;
there remains still some degree of contractility in the respiratory mus-
cles ; it is soon exhausted, however, and the circulatory motion of the
blood ceases with the life of all the organs, of which this fluid is one of
the principal movers.

As to accidental death, it is always determined by the cessation of the
action of the heart and brain ; for, the death of the lungs occasions
that of the whole body, only by preventing the action of the heart, by in-
terrupting its influence oil the encephalic organ. In natural death,
therefore, life becomes extinguished, from the circumference to the
centre; in accidental death, on the contrary, the centre is affected be-
fore the extremities.

Bichat, in his work entitled, Eecherches sur la vie et la mort, has given a
very complete account of the manner in which the organs of the animal
economy cease to act in articulo mortis 5 but like all the authors who
went before him, he has limited his inquiries to certain functions. No
one has attempted to extend them to the phenomena of the action
of the brain, nor has one traced the order in which the various
faculties of thought and of sensation vanish. I shall endeavour faith-
fully to mention the results of several hundred observations of my own
on this subject.

The close of life is marked by phenomena similar to those with which
it began. The circulation first manifested itself, and ceases last. The
right auricle is the part first seen to pulsate in the embryo, and in death
is the last to retain its motion. The phenomena of nutrition, to which
the foetal existence is almost entirely limited, continue, even when the
organs destined to establish a relation with the beings that surround us,
have long been sunk into a slumber from which they are never to be
moused.

The following is the order in which the intellectual faculties cease and
are decomposed*. Reason, the exclusive attribute of man, first forsakes
him. He begins by losing the faculty of associating judgments, and then
of comparing, of bringing together, and of connecting, a number of ideas,
so as to judge of their relations. The patient is then said to have
lost his conciousness, or to be delirious. This delirium has generally
for its subject the ideas that are most familiar to the patient, and his pre-
vailing passion is easily recognized. The miser talks, in the most in-
4iscreBt manner, of his hidden treasures, the unbeliever dies haunted by
religious apprehensions. Sweet recollections of a distant native land,
then it is that ye return with your all powerful energy and delight ! !

After reasoning and judgment, the faculty of associating ideas is next
completely destroyed. The same occurs in fainting, as I once experien-
ced in myself: I was conversing with one of my friends, when I experi-
enced an insuperable difficulty in associating two ideas, from the compa-
rison of which I wished to form a judgment. Yet syncope was not com-
plete,! still preserved memory and the faculty of feeling. I could dis-

* I need not inform the reader, that I am not here speaking1 of the immortal soul,
of that divine emanation which outlives matter, and which, freed from our perishable
part, returns to the, Almighty. I am speaking merely of the intellectual faculties com-
mon to man, and to those animals, which, like him, are provided with a brain. — Ait*

tUictly hear those about me say, he is fainting, and exert themselves tu
relieve me from this condition, which was not without enjoyment.

The memory then fails. The patient who, during the early part of his
delirium, recognized the persons about him, no longer knows his nearest
and most intimate friends.

At last, he ceases to feel, but his senses vanish in succession and in a
a determinate order; the taste and smell cease to give any sign of exist-
ence; the eyes become obscured by a dark and gloomy cloud ; the ear is
yet sensible to sound and noise, and no doubt it was, on this account, that
the ancients, to ascertain that death had really taken place, were in the
habit of calling loudly to the deceased.

A dying man, though no longer capable of smelling, tasting, hearing,
and seeing, still retains the sense of touch : he tosses about in his bed,
moves his arms in various directions, and is perpetually changing his
posture : he performs, as was already said, motions similar to those of
the foetus, within the mother's womb

CCXL. Of the fieriod of death. This period is nearly the same with
all men, whether they live near the poles, or under the equator, whether
they live exclusively on animal or vegetable substances, whether they
lead an active life, or consume their existence in disgraceful sloth, few
live beyond a hundred years. There are, however, cases of men who
have lived far beyond that period, as, for example, those mentioned in
the Philosophical Transactions, one of whom lived to a hundred and
sixty-five.

Few men, however, attain a hundred years, and death even when na-
tural, overtakes us from the age of seventy-five to a hundred.

Difference of climate, though producing no difference in the duration
of life, has, however, a remarkable influence on rapidity of growth. Pu-
berty, manhood, and old age, come on much sooner in warm climates
than in northern countries, but this premature developement, which
shortens the duration of the periods of life, augments, in the same pro-
portion, that of old age.

It is, however, difficult to say, at what precise period old age begins.
Is it towards the fortieth year, when the body begins to decrease and to
decay ? Can the change of the colour of the hair be considered as the
certain sign of old age ? We daily see young men with grey hair. May
we determine its accession by the cessation of the functions of generation
and the incapacity of reproduction ? Fecundity, whose term is so easily
determined in women, by the cessation of the menses, is in man very
equivocal; the emission of the seminal fluid is an uncertain sign, from
the difficulty of distinguishing the mucus of the vesiculx seminales and
of the prostate, from the truly prolific semen. Erection is likewise a
sign not to be relied upon: this state may be occasioned by sympathetic
irritation, by the compression of the bladder, distended with urine, on
the vcsiculae seminales. It is more difficult than is imagined, to deter-
mine, from observation, the period at which, in the human species, the
male is entirely deprived of the power of generation ; and it may be said
that, in establishing the period of from forty-five to fifty-five, as the be-
ginning of old age in our climate, there will be found men arrived at that
state before having reached that age; as, on the other hand, others will
be found after the age of fifty-five with all the characters of manhood.
The climaterical period of sixty-three is the decided and confirmed pe-

444

riod of old age. Whatever regimen may have been followed, man at
that age is truly old, and cannot but be aware of it.

CCLXI. Of the jirobabilities of human life. Man dies at all ages 5 and
if the duration of his life Surpasses that of the lower animals, the grcai:
number of diseases to which he is liable, renders itmuch more uncertain,
and is the cause why a much smaller number arrive at the natural term
of existence. It has been attempted to discover what are the probabili-
ties of life, that is, to ascertain, from observation, how long a man may
expect fo live,, who has already reached a determinate age. From late
accurate observations of the age at which a number of persons have .died*
and from a comparison of the deaths with the births, it has been ascer-
tained) that about one-fourth of the children that are born, die within
the first eleven months of life : one-third between twenty-three months 5
and one-half before they reach the eighth year. Two-thirds of mankind
die before the thirty-ninth year, and three-fourths before the fifty-first; so
that, as Buffbn observes, of nine children that are born, only one arrives
at the age of seventy-three ; of thirty, only one lives to the age of eighty;
while out of two hundred and ninety-one, one only lives to the age of
ninety; and in the last place, out of eleven thousand nine hundred and
ninety-six, only one drags on a languid existence to the age of a hundred
years.

The mean term of life is, according to the same author, eight years,
in a new-born child. As the child grows older, his existence becomes
more secure, and after the first year, he may reasonably be expected to
live to the age of thirty-three. Life becomes gradually firmer up to the
age of seven, when the child, after going through the dangers of denti-
tion, will probably live forty-two years and three months. After this pe-
riod, the sum of probabilities, which had gradually increased, undergoes
a progressive decrease; so that a child of fourteen cannot expect to live
beyond thirty-seven years and five months ; a man of thirty, twenty-eight
years more ; and, in the last place, a man of eighty-four, one year only.
From the eighty-fifth to the ninetieth year, probabilities remain station-
ary, but after this period, existence is most precarious, and is painfully
carried on to the end. Such is the result of observation, and of calcula-
tions on the different degrees of probability of human life, by Halley,
Graunt, Kersboom, Wargentin, Simson, Deparcieux, Dupre de St. Maur,
Buffon, d'AIembert, Barthez, and M. Mourgues, who has just published
his observations, collected at Montpelier, in the course of a great number
of years, and with the most scrupulous accuracy*.

* From the observations made during more recent periods, it would appear that the
mean duration of human life has experienced an increase of nearly five years in the
greater number of European countries. This may be in some measure owing to the
introduction of vaccination, but perhaps the chief causes may be found in the progress
of science and civilization, giving rise to a general improvement in the habits of life,
particularly with regard to ventilation and cleanliness ; to better habitations; a more
ample supply of food, clothing, and fuel; greater sobriety; a more general cultivation
of the soil, and consequent removal of the sources of several diseases; to improved ma-
nagement of children ; and to the advanced state of medical knowledge.

The same causes that conduce to longevity must, of course, increase the population of
a country. The suppression of monastic celibacy, and the more equal distribution of
landed property, consequent on the revolution in France, have tended to increase the
population of that country, notwithstanding the destructive wars in which she has been
engaged. — Copland

I should enter more fully Into this subject, but that it belongs more to
the department of political economy than to that of physiology.

Do the calculations on the probabilities of human life present results
applicable to the generality of cases, and is the mean duration of exist-
ence nearly the same with all men, in all countries and climates ? The
shepherd of the Pyrenees, who lives happy in the innocence of a pastoral
life, breathing the pure air of his mountains, is he, in this respect, sub-
ject to the same laws as the inhabitant of populous cities, exposed to the
inconveniences attending numerous collections of men ; inconveniences
which, viewed in a philosophical point of view, or which greatly over-
rated, have so often furnished a text to the meditations of philosophy,
and to the idle declamations of oratory*.

Does life experience a progressive diminution, in proportion to the
duration of the world, and to say nothing of the time preceding theflood,
when, according to the Book of Genesis, men lived several hundred years,
-'* .. i • i. .. , . .. .. ... j. i - - -

* In order to answer these questions in a satisfactory manner, it would be necessary
to have tables of mortality kept with care in the different countries and climates of the
globe. The religions and superstitions of the East, of all Africa, and of a great part of
America, oppose invincible obstacles to these researches, independently of those re-
sulting from the state of civilization, and the policy of the various governments of these
countries. Judging1, however, from the results already before us, the northern king-
doms of Europe appear to be those in which mankind enjoys the longest term of exist-
ence. The tables of mortality of the empire of Russia, for the year 1811, gave in
828,561 individuals deceased belonging to the Greek church, 947 who had reached an
hundred years and upwards ; amongst whom were 83 of 115 years of age, 51 of 120, 21
of 125, 7 of 130, 1 of 135, and another who had reached 140. m •

According to the abstract of the population returns of Great Britain in 1821, the num-
ber of individuals in England, aged from 90 to 100 years, was 9.90 in every 20,000 ; and,
of those aged 100 and upwards, 34 : the" general mortality was 1 in 67. In Scotland,
those aged from 90 to 100 was 14.13, and 100 and upwards 1.03, in every 20,000. In
Wales, the number of persons aged from 90 to 100 was 17-97, and of those aged 100
and upwards, 50 in 20,000 : the mortality was 1 in 69.

The maximum longevity was found to be in Scotland in the shire of Ross and Cro-
marty. Here the proportion of individuals aged from 90 to 100 was 34.39 to the 20,000,
and of those aged 100 and upwards 9.22. In the shires of Inverness and Argyle, the
proportion of persons aged from 90 to 100 were 32.49 and 29.84, respectively, to* 20,000.
In 1811, the population of Scotland was 1,865,900 ; in 1821 it was 2,135,300.

The first actual enumeration of the inhabitants of England and Wales was made in
1801, and gave a population of 9,168,000, and a mortality of 1 in 44.8. The second was
made in 1811, and gave a population of 10,502.900, and a mortality of 1 in 50. The third
and last, which took place in 1821, has given an enumeration of 12,218,500, and a mor-
tality of 1 in 58.

It appears from these returns, that the healthiest counties in England and Wales are
Pembroke, Sussex, Cornwall, Cardigan, and Monmouth, the mortality in these being 1
in about 71 ; and that the least salubrious are Middlesex, Kent, Surry, and Warwick, the
mortality being in these 1 in about 50. It is not easy to explain altogether the differ-
ence in salubrity in the different countries. Locality is, doubtless, an important agent.
Cities and large manufacturing towns modify greatly the ratio of mortality in a particu-
lar district. This is well illustrated with respect to "London. In 1700, the annual mor-
tality of this city was 1 in 25 ; in 1750, 1 in 21 ; in 1801, and the four preceding years, 1
in 35 ; in 1810, 1 in 38 ; and in 1821, 1 in 40.

It must be evident that the increase or diminution of the population of a district, as
well as the mean term of life in it, must depend upon the nature of the climate and soil,
its mean elevation and temperature, the state of its civilization and cultivation, pursuits
of its inhabitants, and means of subsistence. The government and religion of a country
also exert no inconsiderable controul on the mean duration of human life, and increase
of its population. Together with these already mentioned, many other causes of a
moral and physical nature may be adduced, as influencing, in no slight degree, the ex-
tent, of population, and the salubrity of a district or country. — Copland*

446

did the men of former times live longer than those of our own? This is
very improbable : among the Egyptians, the Hebrews, the Greeks, and
Romans, there were very few instances of persons living to the age of a
hundred years, and instances of longevity are perhaps more frequent
among the moderns.

The art of providing for the wants of life, making daily progress, it is
very probable, that far from being shortened, the term of human life may
be lengthened a certain number of years beyond its ordinary duration.
This idea is, it-is true, contrary to the commonly received opinion of the
progressive depravity of mankind in all ages ; but the golden age never
existed but in the imagination of poets., and the daily complaints of mo-
rose old age have their origin in motives easily understood by the phy-
siologist. He whose sentiment is blunted by a long course of years, is
affected, in a very different manner, by surrounding objects. As to the
old man, flowers have lost their scent and beauty, fruits no longer retain
their flavour. The whole of nature seems dull and colourless. But the
cause of all these changes is within himself, every thing else remains as
it was. Always equally fruitful, Nature exposes every thing to the action
of her inexhaustible crucible ; maintains every thing in a state of ever-
lasting youth, and preserves a freshness ever renewed. Individuals die,
opecies are renovated : life every where arises in the midst of death. The
materials of organized bodies enter into new combinations, and serve in
forming new beings, when life ceasing to animate those to which they be-
longed, putrefaction seizes upon them, and effects their destruction.

CCXLII. Of putrefaction. Here the history of life ought to termi-
nate; if, however, it be considered that the changes which bodies expe-
rience, after death, throw a considerable light on its means, its ends,
and its nature, there will be an obvious necessity for shortly inquiring
Into the different phenomena which accompany the decomposition of
animal substances. And this investigation appears to me to belong to
the department of physiology, until the aspect of the body ceases to re-
call the idea of its former state, and until the last lineaments of organi-
zation are completely effaced. As soon as life forsakes our organs, they
become subject to the laws of physics., operating upon substances that are
not organized. An inward motion takes place within their substance.
and their molecules have the greater tendency to become separated from
one another, as their composition is more advanced. Chemistry informs
us that the tendency to decomposition of bodies is in direct ratio to the
number of their elements, and that a dead animal body is capable of re-
maining unchanged, in proportion as its composition is more simple, and
its constituent principles less numerous and less volatile.

Before putrefaction can come on in the human body, it must be en-
tirely deprived of life, for the vital powers are most powerfully antisep-
tic, and one might say that life is a continued struggle against the laws
of physics and chemistry. This vital resistance, alluded to by the ancients
when they said, that the laws of microcosm were in perpetual opposition
to those of the universal world, and that these, in the end, prevailed; this
power, which is in a state of perpetual re-action, manifests itself in life :
the latter, considering only the results, might, therefore, be defined as
follows : the resistance ofiposed by organic bodies to the causes incessantly
tending to their destruction. By attending to all these phenomena, it will
be seen that all of them tend to one end, the preservation of the body,
and that they obtain it, by keeping up a perpetual struggle with the laws
which govern inorganic substances.

447

Tf might appear singular, that death should aftorcl a just idea of life,
did we not know that it is by comparing, that we are enabled to distin-
guish, to judge, and to arrive at knowledge*.

Putrefaction takes place and is completed, only in substances deprived
of life. A mortified limb loses its vitality, before putrefaction comes on;
and if nature preserve sufficient energy to resist this destructive process,
she draws, by a line of inflammation, the separation between the dead
and the living part. Life and putrefaction are, therefore, two absolutely
contradictory ideas ; and when, in some diseases, there is observed a ten-
dency in solids and fluids to spontaneous decomposition, this tendency to
putrefaction should not be mistaken for putrefaction itself.

Several conditions are required to enable putrefaction to affect the hu-
man body after death. In the first place, a mild temperature, that is,
above ten degrees of Reaumur's thermometer ; in the next place, a cer-
tain degree of moisture; and lastly, the presence of air. This last con-
dition, however, is not so necessary as the two former, since substances
undergo putrefaction in a vacuum, though more slowly. The air conse-
quently promotes a decomposition, only by carrying off the element which
rises in vapours. On the other hand, an icy cold, or a degree of heat ap-
proaching to boiling, prevents it; the former, by condensing the parts ;
the second, by ""depriving them of moisture, the complete absence of
which, accounts for the preservation of the Egyptian mummies.

The phenomena of putrefaction, resulting from a series of peculiar at-
tractions, are modified in various ways, according to the nature of the
animal substances which are subjected to it, to the media in which it
takes place, to the different degrees of moisture and temperature, and
even according to its different periods. Notwithstanding these innume-
rable varieties, one may say, that all exhale a certain cadaverous smell,
are softened, increase in bulk, acquire heat, change colour, assume .a
greenish, then a livid and dark brown colour 5 there are, at the same
time, disengaged a great number of gaseous substances, of which ammo-
nia is the most remarkable, either from its quantity, or from being given
out by animal substances, from the moment when decomposition begins,
to the period of the most complete dissolution. This gas produces the
pungent and putrid smell which exhales from dead bodies.

Towards the termination of putrefaction, there is disengaged carbonic
acid gas, which, combining with ammonia, forms a fixed and crystalliza-
ble salt. Besides these products, there are given out sulphuretted and
phosphoreited hydrogen, or combined with azote, carbonic acid, and all
the substances which may be produced by their respective combinations.
In the last place, animal substances, when reduced to a residue containing
oils and salts of different kinds, form a mould, from which plants draw
the principles of a luxuriant and vigorous vegetation. The bones, those
least alterable parts of the organized machine, in time, become dried by
the slow combustion of their fibrous part, and by the evaporation of their
medullary juices. At last, reduced to an earthly skeleton, they crumble
into dust, and this dnst is dissipated, on opening the tombs in which they
were laid.

Thus, in the course of time, is effaced all that could recall the idea of
our physical existence.

* See APPENDIX, Note M M^ for some remarks on the signs of deatk

448

Putrefaction, considered in a philosophical point of view, is but a
means employed by nature, to restore our organs, deprived of life, to a
more simple composition, in order that their elements may be applied to
new creations (circulus xterni motus*. Nothing, therefore, is better proved,
than the metempsychosis of matterf ; which warrants the belief that this
religious dogma, like most of the fabulous worships and imaginations of
antiquity, is but a veil ingeniously thrown by philosophy, between nature
and the ignorant.

* Beecher, physica subterranea.

f Matter is eternal, in this sense, that the molecules of bodies merely pass from the
one into the other; they survive the destruction, or rather the dissolution of organic
and inorganic beings, when the former, ceasing to live, restore to the inexhaustible
fund of Nature, those elements which she lends without ever parting with them.

Manciple nulli datur, omnibus usu. Lucret lib. III. — Author's Note,

APPENDIX

BY JAMES COPLAND, M. I).

CHAPTER. I.

Of Life.
Note A.

PtfYSioiOGiSTS are divided into those admitting a principle of life, and those attribu-
ting the vital phenomena to organization solely — the latter class contending that life
pre-supposes organization, the former that organization pre -supposes the presence of
life. An attentive consideration of the phenomena presented by the whole range of or-
ganized bodies, and a fair contrast instituted between these and the changes which inani-
mate matter exhibits, will readily convince the most unbiassed by preconceived notions,
which of the two doctrines to prefer.

Those who contend that life is the result of organization, ought to explain in what
manner the organization itself took place ; they should show the means employed to
produce the disposition of parts, which they conceive requisite to give rise to vital
phenomena. If they deny the primary influence of a vital power, associated with the
particles of matter, let them explain by what other agency the different atoms can as-
sume organic actions. All effects must have a cause, and it is better to assign
one according to which difficulties may be accounted for, than to contend for the effi-
ciency of properties or powers, of the existence of which we have no evidence, and
which, even granting them to exist, can only be considered as inferior agents, or cer-
tain manifestations of a vital principle.

With respect to this class of Physiologists, it may be remarked generally ; — 1st. That
explanations of organization, which admit not of the primary and controlling influ-
ence of vitality, however applicable they may seem to those who look only at the gross
relations of things, cannot satisfactorily account for the origin and nature of the pheno-
mena to which they relate ; for, however terms may be substituted, or illustrations mul-
tiplied, the changes which continually take place in living bodies cannot be explained
by means of the laws and affinities which characterize the combinations of inorganized
matter.

2d, In order to explain the phenomena, which are more justly ascribed to a vital
principle, the supporters of the doctrine of organism have recourse to the substitution
of properties, occult-qualties, impulses, and motions ; and when required to show
wherein these qualities, impulses and properties are different from those which we ob-
serve in inorganized matter, and are there subjected to our experience, they endea-
vour to get rid of the difficulty by denominating them vital, thus tacitly admitting the
very principle, in the place of which such insufficient properties are attempted to be
substituted ; and after all, without the smallest success in preventing a recurrence to
this principle, of which all these properties, admitting their existence, are nothing
else than the results : for, however we may denominate them, we merelv substitute ex-
pressions which (if they convey any meaning) imply only the existence of certain effects
or operations, which are inferior agents or instruments, under the controul of vitality h:
the production of the organic phenomena.

From this view, therefore, of the subject, it appears that the argument used against
the existence of a vital principle is more verbal than real. The organists cannot even
prove the basis of their doctrine, for they cannot show that organization came into ex-
istence before the effects which they impute to it ; and while they bestow propertied and

A.

2 APPENDIX.

qualities on organized matter-similar to those imputed to a vital principle, and different
from those which characterize Unorganized matter, although they cannot point out the
difference otherwise than by calling them vital, they virtually admit the existence of the
principle against which they contend ; for what principle in nature, we would ask, can
be shown to exist, or how can its existence be rationally inferred, but by certain pro-
perties and qualities, which are peculiar to itself, and which, moreover, as respects this
principle, are dissimilar and greatly superior to, and indeed hold a controlling influ-
ence over all the other properties of matter with which we are acquainted ?

Such therefore being the case, we are justified in recurring to the belief in a vital
principle which, allied to matter, controls its changes and forms, and to which princi-
ple the laws and affinities of matter entirely subject whenever they are embraced within
its sphere of action. By means of this superior principle, we are enabled to explain
the phenomena of the organized preation and of the human economy, but without re-
ference to it we are lost in the mazes of vague hypothesis and groundless supposition.

It has been objected to the existence of this principle, that we cannot demonstrate it
to the senses in any form unconnected with matter. But we are not contending for the
existence of a principle which is material, according to the received notions respecting
matter, otherwise there would be at once an end of the argument ; it is, therefore, no
evidence of the non-existence of this principle, that it does not become visible to our
senses, in an uncombined form : it is, however, sufficiently demonstrable by its effects,
in alliance with matter, in which state it presents proofs of its being equal to those from
which we infer the existence of matter itself.

From these and many other considerations that may be adduced, we conclude that
life is a first principle in nature ; that it exists in various degrees of energy, and in di-
versified conditions and forms throughout her domains ; and that these diversified states
of vital existence are continued, as far as the operation of extraneous causes will admit,
by a specific process, which gives rise to the production of similar beings by means of
ova and germs.

It will be perceived that the generation by which vegetable and animal bodies are
perpetuated, involve the belief that the ova or germs convey an emanation from the pa-
rent of a specific portion of vitality.

As, however, we can form no just conceptions of such a principle but by its effects,
and as we have no experience of these effects unconnected with matter, so we are war-
ranted in the conclusion, that the vital influence is associated with the molecules of
matter forming the impregnating secretions, and the sensible bulk of the ovum. This
is its lowest state of activity or energy, and its influence is chiefly manifested, under
such circumstances, in preserving the elements of matter with which it is associated
from entering into the combinations to which the chemical affinities of these elements
dispose them.

The hibernation of animals presents this principle also in its lower degree of activity.
In either case, and indeed under every circumstance, it is a.cted upon and excited to an
exalted state of existence by most of the active agents in nature. The electric fluid,
heat, and other powers have this effect, while some appear to produce a contrary im-
pression.

The manner in which several of the active agents of inorganic nature thus influence
the energy of the vital principle appears, to have been the chief reason why these
powers hare been substituted for vitality itself.

We have stated, that the manifestations of this principle throughout the vegetable
and animal kingdoms present considerable difference in degree. Its character in the
vegetable creation is more uniform, and its phenomena more simple. We perceive in
this kingdom, under circumstances which furnish the usual stimuli, that the vital ope-
rations of digestion, circulation, respiration, and assimilation, go forward. As soon,
however, as the exciting causes are withdrawn, this principle subsides to a state of less
activity ; and the integrity of such organs and textures as are necessary to the growth
and propagation of the species, is merely preserved by its influence until a returning
impulse excites its energies.

As we advance in the scale of the animal creation, the operations of this principle be-
come more distinct and numerous, and the mechanism provided for the performance
of them more manifest and complex. As they are performed in man and in the more
perfect animals, may be gathered from the body of the work and the notes which
follow.

OF THE ELEMENTARY SOLIDS. 3

Of the Nervous System in the Lower Animals.
Note B.

The lowest order of animals, as the Polypi, &c. has usually been" considered to be
destitute of a nervous system. This, however, is not the case. If we look narrowly
into the structure of the lower animals, we shall find that even the lowest offer traces of
a nervous system : and as we rise through the scale of the animal creation, we shall find
this system becoming more and more perfect in its state of existence, and presenting ap-
pearances of perfection in proportion to the number and extent of functions which the
animal is capable of exerting. Even the Polypus, the lowest of the animal kingdom,
seems to possess a nervous system, in the simplest state of existence. If this apparently
homogeneous animal be examined with a powerful microscope, numerous globules, en-
tirely resembling those seen in the nervous system, appear disseminated throughout its
structure. As a result of this simplicity of conformation, it presents no perfect manifes-
tation of sensibility and contractility. It is not constituted ot separate textures and
organs destined to perform specific purposes ; and, consequently, as no relation or band
of union is requisite between its parts, as in those animals which have particular organs
or structures which perform, particular offices ; and as each of its individual parts per-
forms the functions of the whole animal, so its nervous system is disseminated through-
out its structure, without being arranged into cords of communication or centres of re-
inforcement as in those animals, which, endowed with distinct organs and perfect func-
tions, possess both.

As we rise in the scale, on the contrary, we perceive,in the more perfect and in the
highest animals, the intimate texture of the nervous system, arranged so as to form com-
municating chords between organs which are distantly separated from each other, and
not only are they provided with these, but each viscus frequently possesses in addition
a separate nervo'us centre, on which the functions performed by that viscus depend :
whilst the former arrangement is calculated to preserve a reciprocity of action — a mu-
tual dependence of parts and of functions, the latter generates a vital influence, modi-
fied in kind and in degree to the part which it actuates, which influence, in conjunction
with what the organ may receive'from a common centre, and what may be generated in
the nerves of its own structure,- is exerted in the production or the functions of which
the conformation of the organ is but the mechanical instrument. Thus the vital in-
fluence is furnished to the different viscera in proportion to, and suitably with the na-
ture of, its expenditure in the more complex and more complete exertion of the opera-
tions which each of them is destined to fulfil.

Respecting this subject, therefore, the following propositions may be stated : — That
corpuscles or globules, entirely similar to those of which the nervous system is com-
posed, according to the observations of Prochaska, the Wenzels, Bauer, and Edwards,
are found desseminated, without any regular order, throughout the apparently homo-
geneous structure of the lowest order of the animal kingdom : that, as we rise in our
observations through the scale of animals, we perceive this dissemination existing only
in the mucous structures, and we observe a distinct nervous mass, or masses; am:, as
the animal presents separate organs destined- to the vital operationSj so this intimate
nervous structure becomes disposed into cords of communication, each organ possess-
ing in addition — the higher that we ascend in the scale more especially — a detached
but dependent mass of reinforcement, which varies in form, appearance, and connexion
with -other organs, or with other parts of the same system, according to the functions
which it is destined to actuate.

Of the Primary Solids and Compound Textures of the Body.
Note C.

The intimate or elementary constitution of the animal textures has long engaged the
attention of Anatomists and Physiologists. As researches respecting this subject can
only be prosecuted by means of the microscope, the result must, therefore, be received
with some degree of reservation, unless they coincide with the observations of former
inquiries, or be confirmed by subsequent observers, From amongst those who have

4 APPENDIX.

engaged in this species of investigation, J. F. Meckcl is entitled to much confidence on
account of his talents and industry, and the results of his labours claim particular no-
tice, as they confirm much that has "been recorded by former observers.

According to the views of this physiologist, the solids and fluids of the human body
may be reduced to two elementary substances : the one is formed of globules, the other
of a coagulable matter, which, either alone or united to the former, constitutes the liv-
ing fluids, when it is in the liquid state, and gives rise to the solid tissues when it as-
sumes the concrete form.

The globules present, in their nature and aspect, differences which are relative to
the situations in which they are examined. They appear in the blood, flattened, and
composed of a central part which is solid, and of an exterior portion, which is hollow
and vesicular. Those found in the kidneys are smaller than those of the spleen ; and
the globules of the liver are still smaller. Those contained in the substance of the
nerves present a less volumn than those observed in the blood.

Globules exist not, according to Meckel, in the proper structure of cellular tissue, of
fibrous and cartilaginous parts, and of the bones. On the contrary, they abound in
nerves and muscles, and determine their nature and colour. Some of the fluids, also,
as the urine, contain no globules, whilst they are abundant in the blood, in the ch}le,
the lymph, milk, &c.

During the hrst period of conception, the mucous and homogeneous mass which con-
stitutes the embryo, contains no globules ; it is not until a more advanced period that
it is composed of two substances, the one fluid, the other solid. These two elements
seem to influence the form of the fibres and plates in which animal substances are dis-
posed. The laminated tissues arise almost exclusively from the fluid matter. The
fibrous tissues may also be produced from this matter alone, as in the tendons, &c. ;
they are, however, more frequently formed from the union of the globules with the
concretive fluid, as may be observed in the nervous and muscular textures.

These observations of Meckel respecting animal organization, it ought to be noticed,
bear a near resemblance to the opinion entertained by Pfaff, who considered the ele-
mentary tissues to be formed from a series of molecules and globules, and to be diffe-
rent according to the presence and influence of the latter form of matter. The idea
of a fluid substance, capable of concretion, is analogous to the opinion of the ancients
especting the substance denominated by them gluten. It is the cellular tissue, accord,
ing to Meckel, which represents that substance ; and, in fact, he regards this tissue as
a species of concrete fluid, possessed of the properties already indicated.

It must, in our opinion, be admitted that the theory of Meckel possesses claims to a
favourable notice. It is the result of observations which accord with those of others ;
it is also simple, and is easily to be reconciled with the phenomena which living tex-
tures present.

Dr. Meyer, of Bonn, (Journ. Complem. dee Scien. J\Tcd. Nov. 1821.) also considers
that two kinds only of elementary texture exist in animal bodies. The one is, accord-
ing to him, composed chiefly of capillary vessels, and is formed from the assemblage of
these vessels : under it he arranges cellular, serous, fibrous, and mucous tissues : tho
other possesses a proper and peculiar parenchyma, composed of globules, or of an or-
ganic pulp ; such are the glands, the bones, muscles, nerves, the brain, and spinal
cord. The first set of organs is a continuation, in his opinion, of the vascular system ;
while the second, on the contrary, is farther removed from such a connexion. Foreign
substances introduced into the circulation, pass immediately, and with rapidity, into the
former textures, while they either fail altogether in penetrating, or insinuate themselves
much more slowly, and after quite a different manner, into the parenchyma of the lat-
ter organs. The one class seems to appertain in general to the system of secretion ; the
other class of textures neither secrete from their individual influence, nor can they of
themselves add to their nutrition. The first appears to be nourished by the imme-
diate, rapid, and continual access into the fluid part of the blood ; the second by a slow
and periodic deposition, and conversion into their proper substance, of the sanguine-
ous globules of the blood, by means of the influence of the vascular extremities upon
the blood which they contain.

The primary solids, or rather, the elementary fibres* of the human body, and of the

* It should be kept in recollection that fibre is used as signifying an elementary ani-
mal substance ; — tissue indicates a certain arrangement of the former— a peculiar struc-
ture of parts : — and organ signifies a compound or complex part which performs func-
tions peculiar to itself.

OF THE ELEMENTARY SOLIDS. 5

higher classes of animals, cannot be considered with propriety, to be more than three
•—the celhtlar or laminar, the muscular, and the nervous.

1st. The cellular fibre is the most essential to animal existence, and is found in every
individual of this kingdom. It consists of an assemblage of minute lamina and delicate
filaments. It is neither sensible nor irritable, and is chiefly composed of a nearly com-
plete gelatine.

2d. The muscular fibre is not so generally distributed throughout the animal kingdom
as the former, for it is not found in the Zoophites.

3d. The nervous or medullary fibre. The nature of this tissue has been the subject
of much investigation. Mr. de Blainville thinks that it originates in the muscular fibre,
as this latter takes its origin in the cellular substance.

To these fibres Professor Chaussier has added a fourth, namely, the albugineous fibre,
which is satiny, white, and very strong ; and is neither sensible nor irritable. The ma-
jority of anatomists, however, consider it as merely a very condensed variety of the
cellular fibre.

These fibres may be called the first order of solids, as they serve to form all the other
tissues and organs of the body. The cellular substance, for instance, is spread out,
and condensed into membranes, or rolled up in the form of vessels ; muscular fibres
also assume the form of membranes, concur to the formation of vessels, and constitute
muscles; nervous fibres produce the nerves, &c. Finally, those primary solids asso-
ciate in various forms, and give rise to the compound solids, as the bones, the glands,
&c. : and even to those of a more complex nature, as several of the thoracic and ab-
dominal viscera. Indeed, every species of solid has for its base cellular substance,
which is penetrated by nerves and vessels. The viscera, for example, are of this na-
ture, having moreover membranous envelopes. The bones also consist of a similar tex-
ture, and of a deposition of phosphate of lime in their cellular substance. (See Ade-
lon's Physiol. vol. i. p. 108.)

Those primary solids, or most simple anatomical constituents which we have just now
particularized, associate in various forms, giving rise to compound solids or tissues, which
are characterized not only by their form and nature, but also by the functions which
they perform.

These animal textures or compound solids were first arranged with any degree of ac-
curacy by Bichat ; and however successful future researches into their ultimate nature
may be, or whatever classifications may be proposed by future inquirers, he is still en-
titled to the honour of having introduced a philosophical analysis into anatomical and
physiological science. The arrangement of the tissues which this great man adopted,
is as follows : — the exhalent, absorbent, cellular, arterial, venous, nervous of animal life,
nervous of organic life, osseous, medullary, cqrtilaginoiis, fibro-cartilaginous. fibrous, mus-
cular of animal life, muscular of organic life, mucous, serous, synovial, glandular, dermoid,
epidermoid and cor neus or pilous, systems. Mr. Adelon has lately proposed another classifi-
cation, possessing some advantages over that of Bichat. He has reduced the number of
textures or systems to twelve, viz. — the cellular, vascular, nervous, osseous, cartilaginous,
fibrous, muscular, erectile, mucous, serous, corneus or epidermoid, and parenchymatoiis.

Professor Mayer has recently adopted a classification of the animal textures, or com-
pound solids, founded on his views respecting the elementary fibres, or primary solids.
He recog*nises only seven systems, viz. — 1st, the lamellated tissue ; 2d, the cellule-fibrous
tissue; 3d, the fibrous system ,- 4>tfi, the cartilaginous tissue : 5th, the osseous tissue ,- 6th,
the muscular fibre ; and 7th, the nervous tissue. Jlibliothcyue Geimaniqite. (*/V0. 8.

The arrangement of this class of solids, which we would propose, is nearlj'the same
as that given at another place. (London Medical Repository for July, 1823.) Employ-
ing the term tissue generically, we would divide the compound solids of the body into
two classes, viz. general systems, and particular textures.

I. GENERAL SYSTEMS. _Under this class we would arrange, 1st, the cellular system ,-
2d, the nervous system, which comprehends two orders, viz. A, the involuntary or gang-
lia! order of nerves, or the system of the great sympathetic — and K, the voluntary order
of nerves; 3d, the muscular system, which also embraces two orders — JL, the involuntary
order of muscular fibres, and B, the voluntary order of muscular fibres ; 4th, the vascu.
lar system .- this system has four orders, viz". A, the arterial order of vessels : B, the
capillary order ; C, the venous order ; D, the absorbent vessels, including a, the lym-
phatics, and b, the lacteals.

II. PARTICULAR TEXTURES. This class includes, 1st, the mucous textures ; 3d, serous
textures ; Sd, the fibrous textures, embracing the fibrous, the fibro-cartilaginous, and the
dermoid ; 4th, the cartilaginous textures ,• 5th, the osseous textures / 6ths the erectile lex-

APPENDIX.

tures ; 7th, the glandular textures, including the parenchyma of the viscera ; 8th, the
corneous textures, embracing Jl, the pilous, and D, the epidermoid textures.

Proceeding synthetically, we may arrange all the solids of which the animal body is?
composed after the following manner.

CLASS I. OR ELEMENTARY ANIMAL SOLIDS.

The cellular fibre. The nervous fibre.

The muscular fibre.

CLASS II. SECONDARY OR COMPOUND ANIMAL SOLIDS.
ORDER I. GENERAL SYSTEMS. '

The cellular system.^ The nervous system.

Including the adipose tissue. Jl. The involuntary or ganglial order

of nerves, or system of the great sym~
pathetic.

JB. The voluntary order of nerves.
Ths muscular system. The vascular system.

A. Involuntary muscles. Jl. Arterial vessels.

B. Voluntary muscles. J5. Venous vessels.

C. Absorbents.

a. Lymphatic absorbents.

b. Lacteal absorbents.

ORDER II. PARTICULAR TEXTURES,

Mucous textures. Serous textures.

Erectile textures. Fibrous textures,

Jl. The fibrous.

Ji. Fibro-cartilaginous textures*
C. The clermoid textures.

Glandular textures. Corneous texture.

Cartilaginous textures. Jl. The epidermoid.

Osseous textures. M. The Pilous.

CLASS III. ASSOCIATED OR COMPLEX ANIMAL SOLIDS.
ORDER I. OR&ANS OF NUTRITION.

Digestive organs. Organs of absorption and circulation.

Organs of respiration and assimilation. Organs of secretion and animal heat,

ORDER II. ORGANS OF RELATION.

Organs of sensation. Organs of voluntary motion*

ORDER III. ORGANS OF REPRODUCTION.

Organs of generation in both sexes.

Of Sensibility and Contractility.

Note D.

Sensibility. — The phenomena classed by the author under this property of Animal
Life, at p. 19 and 20, are evidently refcrrible only to organic contractility, \vith which

OF SENSIBILITY, 7

r.ll classes of animals are endowed, and which, in the lowest orders and in some vege*
tables, assumes the appearance of sensibility. In these, however, we have no reason
to infer the presence of sensibility, merely because they contract under the influence
rfa stimulus; for the contraction may take place without the existence of this property,
from the effect produced by the stimulus upon the organization of the contracting- part.
Indeed we cannot suppose that sensibility is present where the parts generally observed
to be instrumental in its production are not found to exist ; — a sensation cannot be sup-
posed to be produced where there neither is an organization suitable to receive, a.
channel to convey, or p.n organ to perceive an impression. We should, therefore, limit
this term to those phenomena, which the author arranges under that of perceptibility.

With this limitation, sensibility may be called the function of sensation, and a property
peculiar to the animal kingdom. The sensations are derived through the medium of
the senses, and of the nerves, which are distributed to certain parts of the body, and
which communicate with the encephalic centre. On this centi-e the existence of sensi-
bility chiefly depends : the ramifications of its nerves, or the subordinate portions of- it,
being also parts of the apparatus requisite, but not giving rise to this property. As we
ascend in the scale of creation, and as we perceive the senses, and the organs of voli-
tion in more intimate relation with this nervous mass — the encephalon — so we find sen-
sibility becoming more perfect, until, in man, it reaches an extent greatly surpassing
that in which we observe it in any other animal.

In man, and perhaps, in the more perfect animals, the modes of sensibility seem to
vary. These modes may, however, be divided into two conditions, as they are more oif
less active ; namely, conscious or active sensibility, and inconscious or passive sensi-
bility : the former relates to these impressions, either from within or from without,
which give rise to perceptions or ideas, the latter to those that are frequently produced
upon the senses and upon the ramifications of the cerebral nerves, and, owing either to
habit or the want of due attention to them, are not perceived by the mind. In this lat-
ter mode of sensibility, the organ receiving, and the channel conveying, the impression,
perform their offices, but the mind either is not, at the time when the impression is
made, in a state to receive it, or receives it so imperfectly, from its weakness or its
transient nature, as not to give rise to consciousness. This mode does not necessarily
imply a difference in the degree of sensibility, but a condition in which it exists, owing
either to its being excited by other impressions, or to its enjoying repose from being
exhausted at the time when the impression is made ; it is a state to which the highest
manifestations of sensibility, as well as the lowest, may be occasionally subject. It is,
however, merely a relative mode of this property, and the relation subsists entirely be-
tween the state of the cerebral organ which perceives, and the force and duration of the
impression made upon the organ of sense. Thus when the sensibility is actively occu-
pied with a particular object, and an impression is made at the same time upon a dif-
ferent organ from that through which the perception, with which the mind is engaged,
was conveyed ; the second impression may affect the senses in an evident manner, and
even so as to influence volition, yet we may be inconscious of its operation, and no ac-
tive perception may result from it. If, however, the second impression be stronger or
more vivid than the first, or if, from various circumstances besides, it should excite the
cerebral functions, active sensibility or consciousness is the result.

As sensibility, according to this view of the subject, is, in its active state, aterm mere-
ly expressive of consciousness in the entire range of this very generally diffused faculty
of the nervous system ; and as this faculty is evidently dependent upon this system, es-
pecially on the more complex part of it which holds relation with surrounding objects ;
and also as we have no reason to attribute the possession of this part of the nervous sys-
tem, to the very lowest orders of animals, particularly to the class Radials, so we must
conclude, that, although a property of animal life, its higher grades are not possessed
by all animals. It may be also stated, that active sensibility, being considered as ex-
pressive of the consciousness of the whole class of sensations, and all the intellectual
and moral operations, varies in its extent throughout the animal kingdom, according as
those manifestations are more or less numerous and perfect. How far the passive mode
of sensibility, or that unattended by consciousness, may be the property of a lowest
orders of animals, is difficult to say. We may, however infer, that, as this condition of
sensibility may take place without an active exertion of this property in the highest
animals, so it may result from a less perfect endowment of sensibility in the lower; ami
as this mode may require a less complex apparatus for its production, inasmuch as its
relations are more simple, so It may be possessed by animals, whose organization and
manifestations do not permit us to conclude that they are capable of evincing sensibility
in its more perfect and active conditions. The relations which this form or mode of
sensibility hold with the numerous instincts of animals, must be evident to all who con-

g APPENDIX.

siderthe subject. The relations, however, which evidently subsist between that form
of sensibility, called organic sensibility by Bichat, and the animal instincts, are much
more numerous, distinct, and intimate.

Organic Sensibility refers to those sensations which are produced in different degrees
of intensity, owing to the existence of certain conditions of those viscera which are im-
mediately subservient to the preservation of the individual and the species — to nutrition
and reproduction, and which are not immediately subjected to the influence of volition.
The conditions of the parts exciting- sensibility are very various, and are the result of
irritations arising from the presence of a stimulus, of unnatural actions supervening in
particular systems or textures, and of the deficiency of that stimulus or influence to
which particular viscera have become accustomed. Many of the changes preceding
this class of sensations, seem to interest, in the first instance, the ganglial class of nerves ;
but, owing to the intimate relation existing between this part of the nervous system and
the voluntary or sentient part, the impression or change is propagated to the brain.
This is the only essential difference which subsists between this and the other forms of
sensibility. It is the brain which perceives in them all ; and, although stimuli, or the
defect of stimuli, may give rise to certain phenomena possessing the characters of the
higher manifestations of this property, in the organs appropriated to the preservation of
the organic system, independently of the sensorium, consciousness or the more perfect
form of sensibility, cannot form part of the results.

Organic sensibility may be active or passive — it may, or it may not, be attended with
consciousness ; and even the inconscious mode of it may indirectly impel to action, or
give rise to many of the manifestations or instincts which characterize the lower ani-
mals, owing to the ganglial centres, either from their organization or connexions, or
from both, performing a greater extent of functions than generally falls to their share.
I^ therefore, the passive form of organic sensibility may propel to action without con-
sciousness or the sensorial sensibility being excited in these animals, we may also ac«
count in the same manner, for many of the instinctive functions being performed when
we cannot trace them to the influence of a cerebral organ. Of all the conditions of
sensibility, its active organic form is the least under the controul of the mental energies
of the individual in which this form of sensibility is developed. It also, in all its modes
of existence, more intimately interests the existence of the individual than the other
forms of sensibility, — it involves a feeling instinctive of life or death in all its active ma-
nifestations.

From this it will be readily seen, how close a connexion exists between organic sen-
sibility and the animal instincts : it does not belong to our plan to trace the connexion
In all its relations.

Of sensibility, generally, we may observe that, in the human species, it is very varia-
ble ; in some persons it is very much exalted, in others very obtuse. It is vivid in early
life and in youth ; after the age of manhood, it gradually diminishes ; as old age advan-
ces, it decreases rapidly; and, in persons who have attained a great age, it is present in
the lowest grade, in which we find it in the species.

Contractility is essentially a vital phenomenon, and it is the result of a change in the
relative position of the molecules composing the solids of a living body. This property
may be divided into the following grades, commencing with the lowest, it being the
most generally diffused throughout nature : —

1. Insensible Organic Contractility, or, that usually denominated tone or tonicity. This
grade of contractility is not confined to the animal kingdom ; it is a property of vegeta-
bles, and of animals not possessed of a heart. It is diffused throughout the tissues. The
vascular system possesses it in the most eminent degree ; and it may be viewed as the
result of the vital influence with which the structures are endowed ; it is more or less
perfect as the vital energy is perfect, and it disappears with the extinction of this prin-
ciple. It is a property of the tissues and of the vessels, which is more or less exerted in
all the vital operations ; in the circulation, the secretions, nutrition, and absorption.
The ganglial or organic class of nerves seem to be instrumental in its production and
preservation, in the animal kingdom.

2. Sensible organic contractility^ or irritability, is that inherent property of contraction
which exists in a!l muscular, and in some other textures. It is excited by the applica-
tion of a variety of irritants. It seems to depend upon the ultimate distribution of the
nervous substance to these parts, and chiefly upon the nerves proceeding from the
ganglia.

Both these species of organic contractility seem to result from one species of influ-
ence with which animal bodies are endowed ; they are the proximate result of vitality,
and merely differ from each other owing to the intimate structure of the parts in which

OF ORGANIC SYMPATHY. g

they arc seated, and to tUe extent to which each of the parts evincing their presence is
supplied with ganglial ramifications.

3. Cerebral Contractility is the contraction occasioned by the will in voluntary mus-
cles. It takes place only in such muscular parts as have nerves proceeding from the en-
cephalon, or rather from the medulla oblongata and spinal cord, terminating in their
structure, and is the result of this conformation and connexion with these large nervous
masses.

The first and second species of contractility result from the ganglial distributions and
influence, the third from the superaddition of the nerves of voluntary motion.

Whilst, therefore, sensibility, in its more perfect grades, is the function of the sensa-
tions, is chiefly confined to certain parts and textures of the body, and is dependent
upon the part of the nervous system of which the encephalon is the centre, contractilty
exists throughout the whole animal structures, although in different grades, and is,
with the exception of the third species, or grade of its existence, entirely independent
of sensibility and volition : — contractility is a general expression of life, sensibility of
the higher functions only of this principle.

Of Sympathy.
Note E.

Baglivi attributed the sympathies to membranous connexion ; Bordeu to the cellular
tissue ; Willis and Vieusens to the agency of the nerves ; and Whitt and Broussais
chiefly to the brain. Rega divided the sympathies into those of sensibility and those of
contractility — a division which has much to recommend it. Bichat offered some very
excellent observations on the relations subsisting between them and the different parts
of the nervous system : but, although these observations were calculated to lead to a
more correct arrangement of the sympathies than had been'formerly offered, it has not
come to our knowledge that any has appeared founded on a better basis than that in-
dicated in the observations of Bichat.

In a preceding note, we suggested that the sympathies should be arranged into the
reflex and the direct — the former arising through the instrumentality of the sensorium,
the latter taking place independently of it, through the means of the ganglial nerves,
and chiefly of those which are distributed to the blood-vessels and which form com-
municating cords between the viscera.

With a view to the illustration of the latter class of sympathies, viz. those which are
direct, and chiefly consist of the sympathetic actions of organic life, we shall offer a
few remarks.

When it is considered that the ganglial nerves alone supply the blood-vessels and
the secreting organs and surfaces ; that they accompany these vessels to the utmost
limits of their ramifications ; that they communicate very freely with each other, and
\vith their chief centre — the semilunar ganglion ; that they give rise to numerous plex-
uses which render the connexion between them still more intimate ; and that they hold
a close relation with the rest of the nervous system through means of communicating
nerves, — the mutual dependence of action between the chief organs of the body, in,
health and in disease, may be easily explained : if, moreover, it be granted that the
most important vital phenomena, as digestion, assimilation, circulation, secretion, ani-
mal heat, generation, 8cc. (see the note on the fwictions of the ganglial system,") in short,
that life itself with all those manifestations of it now particularised, and which have
been usually called organic, result form the influence exerted by this part of the ner-
vous system, through the instrumentality of the vessels, upon the fluid they contain,
and in some measure reciprocally by this fluid upon these nerves ramified in the pa-
rietes of the vessels, and upon the ganglia themselves through which it must of course
circulate, the agency of this system in the production of the class of sympathies under
consideration must be evident. From this view of the subject and from taking into
account the modifying operation of similar textures, the related action of various or-
gans, and, under certain circumstances, the combined influence and re-action of the
sensorium, the numerous relations and connexions of healthy function and of disorder-
ed action may be more satisfactorily traced.

When one organ qr system of parts is excited to increased action, or when its oper>-
tions are diminished or obstructed, we perceive all the other parts of the system whirh

B

15 APPENDIX.

communicate yith it, througihthe medium of the gangial system, experiencing a modi-
fication of their functions, — the action of one or more organs having always an evident
relation with the kind and degree of action going on in the other. In these cases the
relation is sufficiently manifest ; but the kind and degree of it may vary very greatly be-
tween different organs. And the relations may be of the following sorts, as the vital
energies distributed throughout the system are affected in degree or in kind, or in both
ways at the same time.

I. Organic sympathies in which the vital energy of the system evinces various modifica-
tions in degree and distribution ; but in -which it is not changed in kind,

1. Related actions may be characterised by a due proportion of a healthy degree of
the vital forces of the whole system ; but owing1 to the application of an exciting- cause
fo one organ or part, or to two or three organs, these forces may be greatly increased
in them ; as, however, the healthy or medium quantity of the vital forces of the body
is not supposed to be exceeded, there consequently must be a proportionate diminution
of these forces throughout the other parts of the system*.

* "When the natural functions of one organ is simply excited without being diseased,
the functions of the other organs with 'which it. holds communication, by means of the
ganglial nerves, undergoes a relative degree of change, for the excitement of a viscus
is merely an exaltation of its vitality ; and as we exalt the vital actions in one or more
departments of the entire series, we diminish them throughout the rest in an equal pro-
portion ; the excitement being frequently greater or less in some parts, and the di-
minution more or less confined to others.

If, for the sake of illustration, we suppose the vital energies of the system to be equal
to 50 : and, through means of the organic or ganglial nerves to be distributed as fol-
lows ;— to the stomach and intestines — 7 ; to the heart, vascular system and lungs — 8 ;
to the brain and voluntary nerves — 7; to the liver, spleen and pancreas — 6 ; to the gene-
rative organs — 3 : to the urinary apparatus — 4 ; to the surface of the body — 3 : to the
rest of the body — 11 ; we may consider that it is duly proportioned. But if, owing to
the application of certain excitants to one or more organs, as to the stomach and intes-
tines, we exalt the proportion bestowed on these to 13, we shall consequently find the
brain and voluntary nerves possessing only 5 ; — the heart, vessels and lungs 7 ; — the
urinary organs 3 ; — the surface of the body 2 ; and the rest of tbe body experiencing
the loss of the remaining one. If, again, we excite the vital forces distributed to the
heart and vascular system, until they amount to 16, we shall have a febrile condition of
the system in its simplest form, and all the other organs will suffer a diminution in
proportion : the stomach will only equal 4, and so on in proportion. But the vital
forces of the heart and blood-vessels may equal 16 ; and, owing to the arteries of the
brain experiencing1 an undue proportion of this increase, this organ may at the same
time equal 10 ; or, instead of this increase falling to the lot of the cerebral vessels,
those of the viscera may be similarly augmented whilst those of the remaining or-
gans may be proportionally diminished : in such cases we have a less simple result;
but, nevertheless, the increase of the circulating functions is followed by an equal di-
minution of the secreting. Viewing1 the sympathetic connexion of function in ano-
ther direction, we shall suppose that the excited state of vital action takes place in
secreting organs; in this case the nutritive and other animal operations are diminished
in an eq* "*\ degree. Or we shall suppose that the excitement commences in the capil-
laries of an organ, from the presence of an irritating cause, that, owing to these ves-
sels being supplied with ramifications of the same order of nerves which supply the
heart and vascular system generally, the excitement extends more or less throughout
this system ; and that, in comsequence of the continuity of this order of nerves, and
their very frequent reticulaiions and inosculations, not only do the heart and arteries
experience the excitement produced at a part of the extreme circumference, but the
\vhole body suffers a relative degree of derangement, and hence evinces all the phe-
nomena of sympathetic fever. Thus the capillaries of a particular organ are excited ;
the excitement extends more or less g-enerally throughout the vascular series, and the
nutritive and secreting functions are diminished in proportion as the actions of the
heart and arteries are increased. Many collateral views of this subject may be adduced,
and many of its connexions traced, as well as various modifying influences, both in and
out of the body, appreciated,— all tending to establish the positions that it is chiefly to
the ganglial nerves we ought to attribute the manifold phenomena of related action
v.-hich we observe in the animal econemy. At this place we have only considered one
of the genera belonging to this class of sympathies, namely, that which comprehends
the most simple of the related actions — those which supervene in the system without
nn increase or diminution of the whole amount of the vital energies with which the

OF UAlilT, 11

In this order of sympathies there are three relations to be observed, which actually
more or less obtain and constitute the essence of the subject, or the actual condition of
the animal functions under consideration : 1st, the relation may respect the increased
actions subsisting in two or more organs ; 2d, it may be viewed between the increased
functions of one part and the diminished functions of another ; and 3d, it may regard the
diminished functions observed in those parts which do not participate in the excitement ;
the relation being most immediate in the first, and least so in the third of these forms.

2. The sympathetic or related actions may be attended with a diminution of the sum
of the vital energies throughout the system. In this case the different relations pointed
out above, may nevertheless exist, or one or two of them, may only be remarkable ;
the chief difference here being that the sympathies of this order are generally induced
by agents, which, while they diminish the entire sum of vital energy, act more deci-
dedly upon particular organs or systems of parts.

3." The sympathetic operations may be characterized by a somewhat greater amount
of the vital" energies of the whole body. In this order of sympathies the three rela-
tions particularized above also subsist ; for although the entire sum of vital actions may
be greater than what is usually bestowed on the system, it may be so much increased
in some organs as to be greatly "diminished in others. This condition of functional sym-
pathy seldom continues long- until it subsides to the first, or, from exhaustion of the vi-
tal energies, to the second order just now particularized.

II. Organic sympathies in -which, in addition to various modifications in degree and dis-
fribution, the vital energy of tlie system suffers a change in its kind.

1. — Sympathetic actions in which the general amount of the vital forces is natural in
degree but vitiated or modified in kind, the relation being evident — 1st, mutually be-
tween these functions which are increased ; 2nd^ between the actions which are augmen-
ted and these which are diminished : and 3d, between those only which are diminished.

2. — Sympathies ill which the entire sum of vital energy is both reduced in degree
and modified in kind ; the relation between its distribution in the various organs being
the same as just now pointed out.

3. — Sympathies in which the amount of the whole vital energy is both heightened in
degree and modified in kind. In this order the distributed and the relations to which
such distribution gives rise, are the same as already adduced.

The application of this classification, and of the views wliich it embraces to rnedi-*
^ine, must appear evident.

Of Habit.
Note F.

^Ve have before said that the effects of habit upon our voluntary organs are very
different from thoee which result from its influence, on the viscera of organic life. This
difference is, however, chiefly in degree ; for, sensibility, as there is eveiy reason to
suppose, from its most vivid state of existence until it merges in contractility, and in its
various modes of manifestation, differs chiefly in degree, and as is bestowed in some
. one mode and degree to all the organs of the body, although it be more particularly
limited to one of their tissues, and also as the influence of habit is chiefly exerted upon
the sensibility of the system ; so it follows that it modifies more or less/all the animal
and organic functions, although it acts in the most manifest manner on those organs
which are in the closest relation with the sensorium or functions of the brain. Thus
the stimulus which excites the action of the sensorium produces a much less intense ef-
fect by repetition, but the repeated employment of the same food, or of the same pur-
gative, does not materially less excite the action of the viscera, to which they are respec-
tively applied. As the 'influence of habit, therefore, is chiefly an the sensibility of
the system, so it follows, that, when the organic sensibility of the involuntary organs
is repeatedly excited, it is then that the diminished effects of the excitant upon them

body is endowed. The other kinds of related function have been pointed out in the
above arrangement of this class of sympathies ; and we cannot farther allude to them
here ; indeed it would be much beyond our limits to consider fully the different kinds
of sympathy in their manifold relations ; we have illustrated one more particularly, be-
cause of its importance, and of its having been very generally overlooked.

12 APPENDIX.

are most manifest— -that the more sensibility of our organs is called forth, the more is
the influence of habit remarkable. Those stimuli, however, which act chiefly and the
most exclusively on the contractility of the textures, and those organs principally con-
sist in the exertion of this principle of life, have their operations the least impaired by
repeated employment ; indeed, in many instances those organs have their functions in-
creased and rendered more perfect by frequent exertion. Hence, independently of
degree, is the chief difference in the influence of habit on the voluntary organs of the
body.

Of Inflammation,
Kote G,

As the author has taken occasion to give his opinion respecting the proximate cause
of inflammation, we shall follow his example, and briefly illustrate the view which we
entertained of it, and published in a thesis on rheumatism, in 1815, and more recently
in a paper on the functions of the ganglionic nerves, contained in the London Medical
depository for May 1822. On these occasions we defined active inflammation to be the
result of a morbidly excited state of the gangliul nerves supplying the capillaries of the
affected part, or a derangement arising from the unnaturally exalted condition of these
nerves on which the functions of the capillaries depend.

One of the chief inquiries respecting its nature, and physiological relations, is whe-
ther this exalted or excited state of these nervous fibrillae is one of simple excitement
or no, — whether the natural functions of these fibrillie be merely increased above their
healthy or ordinary pitch, or whether or no they are also otherwise changed. In the
definition, we said morbidly or unnaturally excited, thereby indicating that the func-
tions or influence of these nerves are not only simply increased, but also increased dif-
ferently from what we observe in a healthy part, from the application of a stimulus*
both as respects duration and kind of action.

1. As respects the duration of this exalted state. In the vascular phenomena dis-
played by blushing, or by the application of a gentle stimulus, the effects soon subside
after the removal of the exciting cause ; because the nervous influence exerted on the
capillaries is simply increased without the mode or habitude of operation being changed.
But before we can farther explain the duration of excitement we must secondly inquire
into its kind.

2. When a stimulus or irritant is applied to a part, its action seems to be first upon
the ganglial fibrillae supplying the capillaries. The vital influence of these fibrillas
being excited, the actions of the capillaries which they supply are consequently increas-
ed. There is, however, every reason to suppose, that the increase of this influence is
not simple, that it is not only changed in degree, but also modified in kind. The irri-
tant seems to impress the nervous fibrillse of the part, or of the system more general!}',
in such a manner as to prevent it from returning to its natural state for a very considera-
ble time, or even at all ; — the excited action is induced, it continues, and the longer it
continues the less it is disposed to return to its healthy condition. But wherefore does
the excitement continue ? To this we may answer, either because the irritating or ex-
citing cause continues to operate by its actual presence, or more frequently because
the impression made by it, while it changed the degree of nervous influence, also m6-
rlified its state of existence, and kind of operation on the vessels themselves, and the
fluids which they contain. It is, therefore, owing to the impression of causes, or
changes thereby produced in the kind as well as degree of influence exerted by the
yiervons fibrilla?, that we are to impute, 1st, the duration of the excitement ; and 2dlyj
the different phenomena which capillary derangements or inflammations present. A
few of these phenomena we shall particularize.

1. Uneasy sensations from its lowest degree until it amounts to acute pain. Uneasy sen-
sation alone may be considered one of the primary phenomena following the operation
of the exciting cause ; or rather one of the manifestations characteristic of that kind or
state of excitement, or deranged influence of the nervous fibrillse, forming the first se-
ries of the changes induced in the affected part ; and it may be farther kept up by the
subsequent changes induced in the capillaries by the disordered state of the nervous
influence, of which state it is itself one of the manifestations. When the uneasy sensa-
tion amounts to pain, it may be owing either to the degree of change with which the
influence of the nervous fibrill<E, and through it the action of the capillaries are imbued,

OV INFLAMMATION. 13

ar it may arise in consequence of the ganglia! system of nerves communicating their
disordered excitement, which has commenced in them to these cerebral nerves with
which they are associated in the textures : for, as we have already stated, the ganglia!
nerves being plentifully distributed to the capillary vessels in every part and tissue of
the body, must consequently communicate freely, and come closely in contact with the
sentient or voluntary class of nerves, especially in those textures which are abundantly
supplied with them. By means'of this connexion the excited functions of the former class
is very probably communicated to the sentient extremities of the other class, and the sen-
sibility of the latter being thus excited, is still farther promoted by the derangement of
the capillaries which the former nerves induce. But this phenomenon of inflammation
jhay not result exclusively in the one manner or in the other. It may take place in both
ways in the same part, or in the one or the other more or less partially. In those vis-
cera which are imperfectly supplied with the cerebro-spinal nerves, the first alternative
may be adopted. Indeed, in these textures very considerable inflammation may exist
xvithout any other modification of pain than uneasy sensations being felt ; whereas, in
the other organs, whose supply of sentient nerves is considerable, the second explana-
tion may be entertained ; whilst in some viscera both modes of accounting for this mor-
bjd manifestation may be resorted to. But whatever manner of explanation should be
adopted, according to the distinction just now stated, it ought not to be forgotten that
this particular manifestation of disease is modified, throughout its manifold grades, by
the texture of the part effected, and by the exciting and other causes to which it is
indebted for its existence and progress.

According to this view of the subject it will be observed, that we consider the pain
of inflammation as originating in, or caused by, the condition of the particular influence
or function performed by the fibrillse or the ganglia! system of nerves,— as a state of
these nerves produced deranged action of the capillaries to .vhich they are distributed,
and exciting or otherwise disturbing the sensibility and functions of the other class of
p.erves with which they become associated in many of the textures ; whereas the most
acute pains, those which are not necessarily attended with inflammation, and very sel-
dom give rise to it, as those accompanying tic douloureux, trismus, the various forms of
spasmodic diseases, and some other painful disorders which it is unnecessary to desig-
nate, originate exclusively in the fibrillse of the cerebro-spinal nerves. This appears to
be an important and fundamental distinction in pathology, and one which we have
adopted, not without much reflection and pathological research. It accounts for a very
frequent phenomena, namely, the presence of the most violent pain when there are no
appearances o{ inflammation either during its existence or after its subsidence. It shows
also that, with the exception of the countenance, and one or two other parts, excite-
ment commencing in the cerebro-spinal or sentient nerves, has but little immediate in-
fluence upon the capillary circulation ; and it also points out, that whatever influence
these nerves may possess over the circulation and the vital phenomena allied to it,
it is only by means of exciting the ganglial nerves distributed to the structure of the
part, and to the blood-vessels ramifying in it, that any such influences can be exerted.
This, it may be siiown, were it necessary to speculate respecting final causes, is a pro-
vision requisite to the preservation of the textures, and consequently of the animal body;
for if the circulation throughout the different textures and organs were immediately under
the dominion of the sentient nerves, and removed from that of the ganglial, we should
have not only all the phenomena which more strictly belong to it, but all the vital ma-
nifestations of nutrition, secretion, animal heat, &c. which are under the influence of
the gang-Rome system, subjected to continual derangement from the various impulses of
the will and the passions. As these functions, on which the preservation of the indivi-
dual depends, are under the dominion of another and less fluctuating influence, they are
less endangered by the numerous causes of change by which they are constantly sur-
rounded, and with which they hold frequent communication. But, although tiie func-
tions which are immediately vital are those which belong the province of this system,
they may be acted upon either generally or partially through the medium of the ner-
vous system of relation, or of animal life, which system has its own particular functions
to perform, and these occasionally exert no mean influence over those of the former
class.

2. Redness, or the injection of the capillaries -with red blood. This phenomenon has crea-
ted much discussion, It would be foreign to our plan to enter at this place upon the
different arguments which have been entertained respecting it. We shall merely state
our own opinion as to its nature.

The vital influence of the ganglial class of nerves is, as we have just now stated, mor-
bidly increased in the effected part, especially as respects these nerves distributed more
directly to the capillaries. We observe, on every occasion in the animal economy, that

14 APPENDIX.

when the vital actions of capillary vessels are increased, the vessels themselves become
larger, more fully injected, and circulate a larger quantity of blood. Now, if we allow
that an increase in degree forms one part of the change in the vital influence bestowed
on the capillaries by the ganglial neives, it therefore follows that a proportionate change
in the calibre of the minuter vessels should result from such increase as it usually does
on those occasions when it supervenes in a-natural manner.

In shert that one of the changes constituting the acute stage of inflammation is an ex-
alted state of the vital influence distributed by the ganglial nerves to the capillaries of
the part ; an exalted state of this influence always increases the action and caliber of the
capillaries, therefore both must be increased whenever this condition of vital influences
constitutes a part of the primary derangement.

But it has been argued, that when an inflamed capillary is viewed in a microscope,
the current of blood in it is slower, instead of being quicker, than natural. This, how.
ever, arises, as we have stated on another occasion, from the inflamed capillarv vessels
admitting a greater number of red globules, and thus giving rise to the optical illusion
of their slower motion, when in fact they actually move much quicker than when the
vessel admits a single globule at a time, and when the entire space between each glo-
bule moving in the vessel can be seen. Another objection has been urged in support
of the l^pothesis of relaxation or debility of the vessels, namely, that the exposed ca-
pillaries contract upon the application of an irritant; but so do all irritable parts, and so
do all parts, to a greater or less extent, which are supplied with the vital influence. la
these experiments it has not been considered, because it was unfavourable to the hypo-
thesis, that the irritant acts in a two-fold capacity ; it excites irritable fibres to contraction,
and it constringes the structure of the part. These experiments also appear generally
to have been performed under circumstances of disorder, and at a period when the in-
flammation was passing into that stage which is constituted by a greater or less exhaus-
tion of the increased influence which formerly actuated the capillaries.

3. — Increase of the animal heat in an actively inflamed part. — We have contended in
another place that animal heat is the result of the vital influence of the ganglial nerves
upon the vessels and the fluid circulating through them, and that the heat of the whole
body or of a single part has an intimate relation with the degree of Influence which this
system of nerves exerts, especially that part of it supplying the vessels, either as res-
pects the body generally, or as regards the part more particularly effected. If this po-
sition be granted, it cannot be denied that the augmented heat in inflammation is de-
rived from the same source, namely, the increased influence, on the vessels of the af-
fected part, of that particular system of nerves on which the production of animal
heat chiefly depends. (See the Note on the functions of the ganglionic system of nerves. )

From this it will be seen that, we consider inflammation, in its various forms and stages
to originate in, and to depend upon, the altered kind and degree of influence which
the ganglial system of nerves exerts on the capillaries of the part : — that whenever this
influence is greater than natural, the action of the capillaries is greater than natural,
and whenever it is below the healthy condition, these vessels are equally deficient in a
requisite degree of action ; — that the kind of influence is changed as well as the degree
of influence ; and that, as inflammation originates in this class of nerves, it may be con-
sidered as a lesion of the function of these nerves, and therefore occurring more fre-
quently in those tissues which are the least supplied with an additional and a compen-
sating influence from the other parts of the nervous system : hence the reason that in-
flammation is very seldom seen in the muscular fibre, to which the cerebral nerves are
so plentifully distributed, and hence the probable cause that it so frequently attacks
cellular parts, or those which are essentially cellular in their nature.

At this place we have merely considered a few of the physiological relations of acute
inflammation, in a brief and an imperfect manner. The other points connected with
this subject which might be discussed, but which are more strictly pathological, are —
1st, the different characters of acute inflammation, according to the textures in which
it is seated ; 2d, the stages of inflammation, in relation to the individual tissues, down
through their numerous grades until they reach the lowest ; 3d, inflammation in which
the influence bestowed on the vessels by the ganglial nerves is more or less exhausted
or destroyed ; 4th, the state of the venous capillaries and absorbents in the different
stages and grades of inflammation ; 5th, the varying phenomena which this species of
derangement presents according as it is modified by constitutional, peculiarities ; 6th,
the different manifestations of inflammation arising from the nature of its exciting
causes, Sec. These and other relations of this fundamental, and most important part of
pathology, will be considered in an extended manner on another occasion.

OF THE FUNCTIONS OF THE GANGLIAL SYSTEM. J5

Of the Ganglia! or Great Sympathetic System of Nerves.
Note H.

It would be incompatible with the limits of these notes to point out the anatomical
peculiarities and connexions of this important system, or even to enter upon a length-
ened discussion of their functions. We shall therefore conn' ne ourselves to the state-
ment of the general propositions, at which \ve arrived on the latter part of the subject,
and which were contained in a paper on the functions of the ganglionic system of nerves,
read to the Medical society of London in 1820.

It may be proper to remark, that these inferences were deduced from numerous dis-
sections of individal subjects belonging to the different classes of animals, and from se-
veral experiments made in order to ascertain the extent of function which this system of
nerves performs. The observations made on these occasions we will soon have an op-
portunity of describing in a particular manner.

1. The ganglial class of nerves is to be found throughout every order of the animal
creation, commencing with th'e lowest, the Radiatse, and ascending to the highest.

2. The ganglial nerves is the only part of the nervous system with which the lowest
orders of animals are provided.

3. As we ascend the scale of creation another class of nerves is superadded, namely,
the encephalic, with which the ganglial nerves are connected. In the higher animals
possessing only the ganglial nerves, we perceive the ganglial placed on or near the oeso-
phagus gradually assuming more and more the characters of a brain, and becoming
more evidently connected with organs of sense. We also observe the nervous cords
between the ganglia arranging themselves more and more in the manner of a spinal
marrow, as the locomotive organs become more distinct from those of nutrition ; thus
rendering the steps of gradation between the animals provided only with the lowest or
simplest form of nervous ganglia, and those possessed both of ganglia and of animal or
voluntary system of nerves, almost imperceptible.

4. The nerves which are given oft from the encephalic mass and from the spinal mar-
row evince different characters as soon as these parts of the nervous system become dis-
tinct from the ganglia ; and even in progress towards the fullest distinction which they
ultimately attain, the difference between both the classes of nerves becomes still more
manifest

5. In all the more perfect animals, the ganglia and the various distributions, as far as
they can be traced by the senses, even when aided by powerful glasses and minute dis-
section, are entirely different from the nerves derived from the brain and spinal cord,
in their texture, colour, consistence, mode of ramification and distribution ; and they
supply very different organs and textures from those to which the cerebral and spinal
nerves are distributed.

6. Not only in the lowest order of animals may the ganglial nerves be traced before
the voluntary or sentient class of nerves come into existence, but also in the embryos of
the higher animals the ganglia may be distinguished before any traces of a spinal mar-
row or of a brain can be perceived.

7. The ganglial nerves cannot be supposed to originate in either the brain or spinal
marrow—let, because they are observed in the lowest animals, who possess neither
brain nor spinal cord ; 2dly, because they may be distinguished in embryos before ei-
ther the one or the other nervous mass can be traced and Sdly, because they arc-
never wanting in the fcctal state, whereas not only have the brain and spinal marrow
been individually wanting, but the same foetus has been found entirely without both.

8. The difference between this class of nerves and those of animal life is not evinced
only by their respective appearances, by the general distribution of the former through-
out the animal creation, by the history of the embryal foetus, and by the phenomena ex-
hibited by monsters, but it is also apparent from the very different 'effects which are ob-
served in them, as respects both the living and dead subject, on the application of va-
rious excitants and re-agents*.

* The difference between these nerves is

nerves is very remarkable on the application of gal-
vanism ; for, whilst we found that the voluntary nerves could be excited with a few
plates, two hundred could produce only a slightly perceptible effect upon the parts
more immediately supplied with fibrills from the semilunar ganglion. When gajranism
v/as applied to this ganglion itself in the recently killed animal, but little appreciable

16 APPENDIX, \

9. The points of dissimilarity just now instanced evidently show that the gangiia
find their numerous distributions form an independent system in the animal economy :
and that as one thing cannot be said to torm a part of another thing from which it is
essentially different, so the ganglia and their ramifications cannot be supposed to form
a part of the nervous system of animal life, or that which presides over the intellectual
and locomotive functions.

10. The independence of the ganglial system may be farther demonstrated in many
of the lower animals, and in the young- of the most perfect animals; for in these both
the brain and spinal cord may be destroyed gradually ; and, provided the function of res-
piration he not entirely put a stop to, the functions of circulation and secretion will
still be continued.

11. That the dependence of t! is system, and the extent of the peculiar influence
which it exerts in the animal ecu; omy is farther proved in the most perfect animals, by
the effects of disease upon the brain and spinal marrow, either of which may be de-
stroyed to a very great extent, and these organs only which they supply be deprived
of their functions, while those viscera which receive the ramifications of the ganglial
system will continue to perform their actions without evincing1 much disorder, unless
that part of the nervous mass which actuates the contraction of the respiratory muscles
becomes involved in the disease.

12. The ganglia supply with fibrills: all the organs of digestion, assimilation, circu-
lation and secretion.

13. The heart is chiefly supplied with nerves coming directly from this class of nerves,

14. These nerves form a closely reticulated envelope around the arteries of the
throat and abdomen, and around the vena portse : they may be traced in the larger
branches of arteries in the extremities, and of the head, until they reach the brain it-
self.

15. The arteries throughout the body, and indeed all the other parts of the vascular
system, receive nerves directly from no other source than from the ganglia.

16. The same system supplies, in a demonstrable manner, all the involuntary muscles,
and it seems to send flbrillae to several of the voluntary muscles, especially to those
about the centre of the body. It is also liberally distributed to all the secreting glands
and surfaces*.

effect was produced either on the vessels with which it is intimately connected, or upon
the stomach and upper portion of the small intestines. In the majority of instances,
however, these parts seemed to be in a more contracted state while under the g-alvanic
influence. When the influence of the battery (of two hundred plates) was directed
upon the semilunar ganglion of a young cat, it evinced symptoms of pain and distress,
and several irregular contractions of the diaphragm supervened. The effects of galva-
nism were also tried on some of the other ganglia, but they evinced no appearance of
being oppressed by it in the dead subject, and, in the living, the result was equivocal.
On these occasions we experienced great difficulty from the want of proper assistance.
We propose, however, to repeat and to extend these experiments ; and we expect emi-
ment coadjutorship in their performance, and the assistance of a very powerful galvanic
battery.

* If, therefore, the existence of these nerves is every where demonstrable in the
centre of the system, and even throughout its radius, until we arrive at the superficies
or extreme parts of the body, where it may be supposed that they must elude, from
the nature of their organization, the detection of the senses, it cannot be contrary to
the uniform operations of nature, and to the many analogies she presents, to infer, that
they are distributed to the extreme ramifications of the arteries, upon whose more con-
siderable branches they are readily demonstrable. And if they are also shown to exist
in some voluntary mus'clcs, may they not be considered to be present in all, bestowing
upon these muscles their peculiar energies, the nerves of animal life producing only
the functions which usually result from this class of nerves, in addition to those arising
from the involuntary influence or vital energy which these muscles derive from the gan-
glia and tJffcir distributions.

It may be mentioned, that consistently with the opinions we entertained respecting
the independence of, and extent of the functions performed by, the ganglia and their
distributions, that we assign the terms — ganglial system, organic system of nerves, vital
system of nerves, synonymously ; and we use the terms- — cerebro-spinal system of nerves,
voluntary nerves, and sentient system, also synonymously. To this there may be some
objections; but as we did so in the original paper, we wish hot to alter it.

OF THE FUNCTIONS OF THE GANGLIAL SYSTEM. jy

17. From the manner in which the ganglial nerves invest the arteries proceeding
into the brain, and reasoning from analogy, we infer that they accompany the arteries
throughout the substance of this viscus, as in other organs of the body, and that they
influence its vascular functions in a similar manrier.

18. The chief origin or centre of the ganglial system is generally situated, in all the
higher orders of animals especially, about the middle of the body, and, under the name
of the semilunar ganglion, it sends off branches, which form plexuses; these present
modified characters, as respects their external appearance and confirmation, in their
course to their different organs which they supply.

This central ganglion more immediately supplies the organs of digestion, chylifac-
tion and circulation, where the expenditure of the vital Influence is greatest, and^sends
communicating branches to the subordinate ganglia and plexuses.

19. The external characters of the ganglia and of their plexuses and ramifications
vary considerably in different situations, both as respects their colour, their external
form and internal structure.

20. The subordinate ganglia, while they seem to receive a reinforcement of vital in-
fluence from the centre ganglion, modify that influence, and generate an accession to
it, suitable both in kind and degree to the functions of the organs which they are des-
tined to actuate.

21. This class of nerves sends off, and receives cords of communication between the
brain and its subordinate organs, and between the spinal marrow and its distributions :
this seems to give rise to a reciprocal communication of influence between the organs
of nutrition, &.c. and those of relation, and a mutual dependence of function, which is
more intimate and apparent as we rise in the scale of creation, — the independence
of the former class of functions becoming more evident as we descend, and the younger
the animal is as we ascend the scale.

22. The extent and mode of communication between different parts of the volun-
tary nerves, and the ganglia and their distributions, vary very considerably.

23. As this" class of nerves are so entirely different in their appearance, structure,
properties, and mode of distribution, and as they supply very different organs from
those which receive the encephalic class of nerves; so it maybe inferred that they
perform essentially different functions, although these functions, in the higher animals
more particularly, are in close relation with those of the rest of the body.

24. As it is demonstrated, that the ganglial or vital nerves supply the heart, that
they surround and are ramified in the arteries throughout their distribution : that no
part of the vascular system receives, in a direct manner, any voluntary nerves ; and as
it is reasonable to suppose that this provision does not exist without accomplishing im-
portant purposes in the animal economy, ahd as the fibres of involuntary muscles are
evidently supplied from the same source ; and, farther, as we cannot suppose, conform-
ably to the laws of nature, that the bare coats of the vessels, and particularly of the
arteries, without such a provision, could be possessed of any vital properties — so we in-
fer that all the vital phenomena, which the vascular system exhibits throughout the
body, are under the direct influence of this class of nerves.

25. The distribution of these nerves around the arteries, and the manner in which
their nbrillze penetrate the coats of these vessels, seem to evince that they not only
impart to them whatever vital properties they may possess, but that they moreover pro-
duce those changes on the blood to which it" is subject, whilst flowing in the vessels,
and many of those phenomena which this fluid presents soon after it has been taken
from the body.

26. It is also reasonable to suppose that the influence exerted by this system on the
capillaries, and the additional influence which its ramifications bestow on the substance
of the viscera, combine to produce the secretion, in secreting organs and surfaces, and
nutrition throughout the textures of the body. Hence, that the varied phenomena
displayed by the blood itself, by the functions of digestion, secretion*, assimilation,

* No experiment instituted with the intention of showing the influence of the
nerves given off from the brain and spinal cord upon secretion, can prove the reality
of such influence. Because these orders of nerves are not ramified upon the vascular
system, nor do they even supply the capillary vessels. This is a wise provision ; for if
the heart and blood-vessels were directly under the influence of the voluntary nerves,
in any of its divisions, this system would be constantly deranged by it, and vascular
disease be incomparably more frequent and fatal, Such experiments, were they
instituted with thd*utmost precautions, could prove no more than has been shown bv
those of Dr. Phillips and Leirallois, which at most evince that the vital functions resul'-

e

;(g APPENBDt

Sec. result from fhe Condition of the influence which this System, in its centre and dis«
tributions, is instrumental in generating in the vessels and fluids which they contain.
May not a vital influence or atmosphere, as it were, be produced from the extreme
fibrillaB of this system, or between them ad the coats of the capillary vessels, which
influence, whatever may be its state of existence, impresses the fluid circulating- in
these vessels in a manner which produces different effects, according1 to its excess or
defect, or according to other modifications to which it may be subject — in health and
disease, owing to the numerous causes of change to which it is exposed ?

27. The separation from the blood of the materials which supply the waste of the
textures, or give rise to their growth, is the office of this system, which imparts its in-
iiuence to, and operates through the medium of the vascular system.

28. The vital manifestations of the veins and absorbents (with the exception of the
vena ports) arise from the distribution of the system of nerves to the minute arterial ca-
pillaries supplying their parictes, and to the adjoining textures; and, probably, from
the distribution of minute fibrillse to their tunics — an org-anization which, although it can-
not be demonstrated, may nevertheless exist, and thus the vital manifestations of the
venous system may more readily be explained.

29. The ganglial nerves sheathe the vena portse throughout its course in the liver ; and,
from the very abundant manner in which they supply this particular vein, from the con-
formation of the vein itself both as respects its coats and connexions with the texture
of the liver, and with the other vessels, and from the character of the blood conveyed
to and from it, we conclude, — that it is through the vital influence bestowed on the
vena portse by the ganglial nerves, assisted with that belonging to the other vessels and
the textwe of this viscus, that the changes induced in the blood returned from the di-
gestive canal and its allied viscera, and containing a large proportion of absorbed mate-
rials, are produced ; and that the secretion of the bile results from the same influence,
partly as a consequence of these previous changes, and partly as its independent act
exerted both upon the extreme ramifications of the vena portse, and of the hepatic ar-
tery, this secretion consequently proceeding from both the kinds of blood contained by
these vessels.

30. That this system of nerves, by means of the influence derived from its principal
nnd subordinate sources, and numerous distributions, and exerted upon the vascular
system, generates animal heat througout the body ; and that the production of animal
heat takes place in a manner analogous to the process of nutrition and secretion.*

31. The state of animal heat, like other, secretions, will be greatly modified by the
condition, both as respects kind and degree, of the vital influence of the ganglial sys-
tem, and by the state of the blood on which this influence is exerted, which state will
have a double operation in modifying the result. (See the note on animal heat.)

32. It appears probable, from the effects of several agents upon the voluntary and
other muscular parts, when applied immediately to the ganglial or vital system of nerves,
from the general distribution of this system to the capillary arteries, and from the cir-

ing from the ganglial or vital class of nerves may be influenced, in the more perfect
animals, by the destruction of a part of the nervous system with which they have held,
and with which they always hold, a more or less intimate relation ; and that the same
nerves, which, during health, have conveyed a natural stimulus to the vital activity of
particular organs, may convey an artificial one : and when the natural stimulus or ex-
citant is removed, o"r the subordinate function annihilated, the operations to which it
is requisite, in the highest animals, must languish and ultimately decay.

Indeed, it is only reasonable to suppose, that the involuntary nerves, as they commu-
nicate with the organic or vital nerves, convey a natural stimulus, or influence to the
latter, which, if they were deprived of it, after its continued and uninterrupted influx,
the vital functions of the organs enjoying this additional influence, would necessarily
languish, or even be overturned if the privation took place suddenly and completely.
If, however, it were brought about gradually, it might be produced to a great extent,
and in many animals completely.

* The experiments of insulating a limb by dividing all the voluntary nerves and ar-
teries, excepting one arterial trunk, performed by Mr. Brodie, in order to ascertain the
effects produced upon the generation of heat in 'the lirnb, prove this proposition, and
could not fail of giving rise to what was actually observed. For the ganglial or vital
nerves supplying that'vessel could not be completely detached as long as any of the
coats of the artery remained undivided.

OF THE FUNCTIONS OF THE GANGLIAL SYSTEM- 49

cumstance of its supplying and actuating the involuntary muscles, that it also bestows
its proper influence upon those which are voluntary, and that thus it gives rise, in both,
to the phenomenon of muscular parts usually called irritability; the different manifes-
tations of this property, as it is displayed in voluntary and involuntary muscles, resulting
from the accessory supply of the cerebro-spinal nerves which the former class of mus-
cles receives. (See Note F. F.)

33. That the ganglial system appears to be productive of certain obscure sensations
or instinctive impulses (organic sensibility) which are, by means of the communicating
branches of nerves between this system and the cerebro-spinal masses, propagated to
the latter, and from the influence they there excite, become the cause of several mani-
festations, which more immediately proceed from this latter part of the nervous system.

34. This operation of the ganglial system on the functions of the cerebro-spinal sys-
tem is more remarkable when the former is influenced by disease or by a stimulus which
is unnatural either in kind or degree ; or even when a natural excitant, to which this
system has been accustomed, is withheld, whether such excitant operates either direct-
ly or indirectly, or in both ways, as the supply of food, Sec.

35. The communicating branches of nerves between the chief ganglia of the abdo-
minal and thoracic cavities, whilst they are the medium of communication between the
ganglial and cerebro-spinal systems, intercept or moderate, by means of the subordi-
nate ganglia placed in their course, the influences proceeding from one system to the
other. Thus it is that the ganglia in the neck and chest moderate the influence of the
functions of the brain on the heart, and that no impulse of the former can reach the lat-
ter but through the medium of the ganglia ; and so little are the ganglia influenced by
the operations and excitements of the brain, that organic sensibility is only slightly pro-
duced by them. If, therefore, the impulses of passion and volition produce but an ob-
scure effect upon the ganglia and their chief centre, it is not to be wondered at, that the
galvanic influence — which must be very considerable to equal the impulses of volition —
should act comparatively in a very slight and almost insensible manner upon this system,

36. The ganglia on the communicating branches between the internal ganglia and
the spinal cord, intercept the impulses proceeding through this latter channel ; and
while they thus moderate the operations of both the brain and spinal marrow upon the
internal ganglia!, they seem to generate an influence suited to the intermediate place
which they hold.

37. Irritations of the ganglial system appear to act in a slight and obscure manner up-
on the voluntary organs, through the medium of the communicating or conducting bran-
ches between this system and the spinal cord; and, but for the ganglia on their course,
the irritations of the former, and the impulses of the latter and of the brain, would re-
ciprocally act in a manner that would be much more marked, and even in a way that
would be injurious to the whole body.

38. The influence of the ganglial on the cerebro-spinal system, is more marked as
the developement and functions of the former system predominate, as in the lo-vver ani-
mals and in the foetus of those which belong to the highest orders.*

* The following outline exhibits a view of the extent of influence which we have at-
tributed to the ganglionic system : it formed a part of the contents of a treatise on the
anatomy, physiology, and pathology of the ganglionic class of nerves, &c. the publica-
tion of which was commenced in the London Medical Repository, but was discontinued
in order that it might appear in a separate and extended form.

"PABT I. comprehends the following sections : — 1. A description of the organs ge-
nerally called nervous ganglia. — 2. An examination into the distribution of their rami-
fications, or fibrillae, as far as that has been determined, either by my own, or by the ob-
servations of others. — 3. Reasons against the usually received opinion, that they consti-
tute a part of the cerebral and spinal nerves ; and proofs of their forming a distinct
system from the brain, spinal cord, and nerves proceeding from these sources. — 4. An
account of the connexion existing between the ganglia or their ramifications, and the
nervous system, properly so called ; and the mode by which that connexion is eifected.
•5. An inquiry respecting what viscera and textures they supply. — 6. Proofs from the
history of the species, and from comparative anatomy, that they form the first eHbrt of
organization, and are instrumental in the production of the other textures. — 7. Remarks
respecting their state during the formation, progress, and decline of the animal.— 8. In-
ferences from the preceding inquiries.

" PABT II. The functions of the ganglia considered— 1. As they regard the vascular
system, on which they are chiefly ramified — A. Proofs that the ganglia are the primary
and chief source of the heart's action — C. Their power over the arterial and capillary

2Q APPENDIX.

39. As the ganglia of the great sympathetic form an independent system presiding
over certain functions which are essentially vital, consequently they may be viewed as
the system and seat of organic life, and may, therefore, be denominated the vital system
of nerves, whose centre is the semilunar ganglion.*

40. It seems probable, from the circumstances of a separate ganglion or plexus, or
both, being generally assigned to each important secreting or animalizing organ, that the
centre or source of vital influence does not supply the whole vitality distributed by the
ganglial ramifications to the individual organs and textures ; but that the vital influence
proceeding from this centre is reinforced by that which is produced by the subordinate
ganglia, and is not only reinforced, but modified by them, and by their distributions in
the various organs, so as to give rise to the specific difference of function which each
performs ; and that the vital manifestations of particular ganglia are still farther modified
by the communicating branches between them and the cerebro-spinal system, the ex-
tent of modification being relative to the extent to which the nerves of this latter sys-
tem either communicate with, or contribute to supply, or to form, the individual subor-
dinate ganglia.

Lastly. The vital influence, being thus produced from the centre of the body, and"
reinforced and modified by the subordinate ganglia, allotted to the individual organs,
accm-ding to their functions", is propagated along the distributions of the system, on which,
it depends and is inherent, throughout the whole body.

systems inquired into, and the irritability of the latter class of vessels contended for,
and shown to be derived from this cause — D. Evidences of their influence over the se-
creting viscera and textures, a. On the gastric secretions and functions, b. Their con-
trol over the secretions from mucous and other surfaces, and from follicular glands, c-
Over the biliary and pancreatic secretions, d. Over the secretions and functions of the
urinary organs. — E. Their influence on the mass of blood circulating through the heart
and blood-vessels, a. As regards the changes induced in this fluid during respiration.
b. As respects the phenomena which it displays, after having been drawn from an arte-
ry and vein in the general circulation, during various states of the system, c. The power
of these organs in the production of animal heat.

« 2. The functions of these organs, viewed in connexion with the muscular fibres of
involuntary motion. — 3. The probability of their being the chief source of irritability
contended for, and the varying characters of this principle explained, as it is displayed
in the different muscular textures and capillary vessels. — 4. The influence of the brain
and spinal cord, upon the operations of the organs under consideration, viewed, a.
In respect to the manner and extent in which the former affect the contractions of the
heart. 6, As they (the voluntary nerves) ntay affect the capillary circulation of a part,
and proofs of their limited influence over the vascular ramifications, c. With regard
to the small extent of power which the brain and spinal cord can exert over the func-
tions of digestion, unless through the medium of the ganglions. — 5. A general view of
the phenomena to which the ganglial ramifications give rise, when reinforced by the
nerves properly so called. — 6. The manisfestations to which they give rise in the infe-
rior classes of the animal creation. — 7. The functions of the ganglions, as they regard

the generative process, a. In the male. b. In the female 8. Their influence in the

formation and nutrition of the textures ; and in the progress and decay of the animal,
considered. — 9. The effects produced on different animals, by the application of certain

substances to the expansion of these organs 10. The consideration, that the manifes-

taions essentially vital are the result of these organs, entertained, argued for, and ex-
plained from the inferences deduced from the foregoing sections. — 11. A general view
of the doctrines contained in this part of the treatise. — (Land. Med Repos. for Jlfaij,
1822.)

* Violent blows or contusions on the epigastric region, when they do not immediate-
ly destroy the individual subjected to them, depress in a very remarkable manner the
vital energies of the system.' The animal heat is uncommonly diminished ; the surface
is cold and pale ; the pulse slow, and scarcely perceptible ; and the breathing feeble
and very slow. An analogous effect in some respects, is produced by concussion of
the semilunar ganglion, as that which follows concussion of the brain : in the former the
vital or organic actions are either exhausted or destroyed, in the other animal or volun-
tary operations only are suspended.

THE EFFECTS OF LONG PROTRACTED ABSTINENCE. 21

TJie Effects of long protracted Abstinence.
Note I.

The effects of protracted abstinence on the human subject are well illustrated
by the following1 facts :— During- the famine which desolated certain parts of France, in,
the year 1817, especially during the months of April, May, and June, when the miser-
able" inhabitants had exhausted their stock of provisions, and when they were reduced
to live on herbaceous vegetables only as wild sorrel, nettles, patience, succory^ thistles,
the tops of beans, the sprigs of young trees, &c. M. Gaspard, (Journ. de Physiol. Eper.
Al». 3.) observed that a general serous diathesis prevailed, or universal anasarcaof the
cellular membrane, without ascites, jaundice, or any organic lesion of the liver, or of
any of the abdominal viscera. Many women experienced an interruption of the catame-
nia ; and a reference in the register of births subsequently to the communes which suf-
fered from the famine, showed that the number of conceptions was less by more than
one half, during the three calamitous months of that year, than during the same months
of the preceding and following years.

During these months many assuaged their hunger by eating snails, of which an incre-
dible number was destroyed : but those who largely partook of them experienced a state
of stupor, analagous to that produced by belladonna.

A tradesman, impelled by a succession of misfortunes, retired to a sequestered spot
in a forest in Germany, and there resolved to starve himself to death. He put his de-
termination in force on the loth of Sept. 1818 ; and was found 18 days afterwards still
living, although speechless, insensible, and reduced to the last stage of debility. A small

bushes and leaves. On the 17th of Sept. (the second day) he complained of suffering
from cold ; on the 18th he mentioned having suffered from intolerable thirst, to ap-
pease which he licked the dew from the surrounding vegetables. On the 20th he found
a small coin, and with difficulty reached an inn, where he purchased a bottle of beer ;
the beer failed to quench his thirst, and his strength was so reduced, that he took three
hours to accomplish the distance, which was about two miles. On the 22d he discover-
ed a spring of water, but though tormented with thirst, the agony which the cold water
produced on his stomach e ---cited vomiting and convulsions. The 25th made ten days
since he had taken any fo : .! but beer and a little water. During that time he had not
slept at all. On the 25th h- complained of his feet being dead, and of being distract-
ed by thirst ; he was too weak to crawl to the spring, and yet dreadfully susceptible of
suffering. The 29th of September was the last day on which he made a memorandum.
No dissection of his body was made. — Journal der prafthch: Heilkunde, &c- C. FT. Hufe-
land, Marz, 1819.

A criminal, called Viterbi, determined on the 2d of December, to starve himself to
death, in the prison of Bastia, where he was confined. During the first three days of
the attempt, he felt himself progressively tormented by hunger. He manifested no de-
bility during these three days, nor any irregular muscular movement; his ideas continued
sound and he wrote with his usual facility. From the 5th to the 6th of Dec. the much
more grievous suffering of thirst succeeded insensibly to hunger- Thirst became so
acute on the 6th, that without ever deviating from his resolution, he began to moisten
his lips and mouth occasionally, and to gargle with a few drops of water, to relieve the
burning pain in his throat; but he let nothing pass the organs <>f deglutition, being"
desirous not to assuage the most insupportable cravings, but to mitigate a pain which
might have shaken his resolution. On the 6th his physical powers were a little weak-
ened ; his voice was, nevertheless, still sonorous, pulsation regular, and a natural heat
equally extended over his whole frame. From the 3d to the 6th he had continued to
write ; at night several hours of tranquil sleep seemed to suspend the progress of his
sufferings : no change was remarkable in his mental faculties, and he complained of no
local pain.

Until the 10th the thirst had become more and more insupportable : Viterbi, how-
ever, merely continued to gargle, without once swallowing a single drop of water ;
but in the course of the 10th, overcome by excess of pain, he seized the jug of water,
which was near him, and drank immoderately. During the last three days, debility had
:i;ade sensible progress, his voice became feeble, pulsation had declined, and the ex-

22 APPENDIX.

tremities were cold. He, however, continued to write : and sleep, each night, afford-
ed him a few hours ease.

From the 20th to the 12th the symptoms made a slight progress. His constancy nevep
yielded an instant : he dictated his journal, and afterwards approved and signed what
had been written agreeable to his dictation. During the night of the 12th the symptoms
assumed a more decided character ; debility was extreme, pulsation scarcely sensible,
his voice extraordinarily feeble, the cold had extended itself all over his body, and the
pangs of thirst were more acute than ever. On the 13th the unhappy man, thinking
himself at the point of death, again seized the jug of water and drank twice, after
which the cold became more severe ; and, congratulating himself at the approach of
death, he stretched himself on the bed, and said to the gendarmes who were guarding
him, "Look how well I have laid myself out." At the expiration of a quarter of an
hour, he asked for some brandy , the keeper not having any, he called for some wine,
of which' he took four spoonsfull. When he had swallowed these the cold suddenly
ceased, heat returned, and he enjoyed a sleep of four hours.

On awaking (on the morning of the 12th) and finding his powers restored, he fell into
a rage with the keeper. During the two following days, he resisted his inclination to
drink, but continued to gargle occasionally with water/ During the nights he suffered
a little from exhaustion, but in the morning found himself rather relieved. It was then
he composed some stanzas. On the 16th in the morning his powers were nearly annihi-
lated, pulsation could hardly be felt, and his voice was almost wholly inaudible ; his body
was benumbed with cold, and it was thought that he was upon the point of expiring. At
ten oclock he began to feel better, pulsation was more sensible, his voice strengthened,
and heat again extended over his frame ; and in this state he continued during the whol
of the 17th. From that day until the 20th he only became more inexorable in his reso«
lution to die.

During the 19th the pangs of hunger and thirst appeared more grievous than ever :
so insufferable indeed were they, that, for the first time, Viterbi let a few tears escape
him ; but his invincible mind instantly spurned the human tribute. For a moment he
seemed to have resumed his wonted energy, and said in the presence of his guards, " I
will persist, my mind shall be stronger than my body, my strength of mind does not
vary, that of my body daily becomes weaker." A little after this energetic expression,
which showed the powerful influence of his moral faculties over his physical necessities,
an icy coldness again assailed his body, the shiverings were frequent and dreadful, and
his loins in particular, were seized with a stone coldness, which extended itself down
his thighs.

During the 19th, a slight pain at intervals affected his heart, and for the first time he
felt a ringing sensation in his ears. At noon, on this day, his head became heavy ; his
sight, however, was perfect, and he conversed almost as usual, making some signs with
his hands. On the 20th he declared to the gaoler and physicans that he would not
again moisten his mouth, and feeling the approach of death, he stretched himself on
the bed, and said, " I am prepared to leave this world." Death did not this time be-
tray his hopes ; on the 21st he was no more. Until the day of his death this man re-
gularly kept his journal. The delivery of it to his friends was refused. (From the Cor-
sican Gazette.}

Of Digestion.
Note K.

!• Of Digestion in the Stomach. M. Lallemand has drawn the following inferences
from his observations and experiments on digestion :

" 1. That, if it be true that alimentary substances, the most perfectly animalizeo^
contain the most nutritive matter, it does not thence follow that they are the most ra-
pidly digested.

« 2. That, on the contrary, the process of digestion is more long and laborious, as,
in a given volume, the aliment contains more nutritive matter, and vice versa.

" 3. That the aliments do not escape from the stomach in the order in which they
are introduced, but that it is not those which are first altered by digestion that pass the
first : it is those on the contrary, which, containing least alimentary matter, are most
jreiractory to the digestive powers."

OF DIGESTIOK. 23

Conformably to the inferences stated, (in note H. of the Appendix) we consider that,
whatever may be the order in which the ingesta pass the pylorus into the smaller in-
testines, the digestive process in the stomach, and, indeed, throughout the alimentary
canal, is more immediately the result of the vital influence with which the stomach and
intestines are endowed, than of the solvent properties of the gastric juice. We, how-
ever, by no means would be understood to deny that these properties are requisite to
the process, we only contend that they are subordinate to the manifestation of vitality
exerted by the stomach, and that the vital influence of this viscus is chiefly concerned
an its performance. The digestive process, whether that part of it which is performed
in the stomach, or that which is accomplished by the small intestines, appears to be es-
sentially a vital process, whether we view it in man or in any of the lower animals.
Every theory, therefore, which excludes its immediate operation, must be defective.
Conformably to this view, it must be supposed to vary in activity, — as indeed we ac-
tually find that it does, according to the state of the vital influence with which the
organs concerned in its accomplishment are originally endowed, and according to the
state and distribution of this influence with which the organs concerned in its accom-
plishment are originally endowed, and according to the state and distribution of this
this influence throughout the organs and textures at the time when this process
is going forward. We do not deny that the influence which we impute to the
stomach, is one which is not intimately connected with the gastric juices ; on the
contrary, we believe that they are the medium through which it acts; — in short,
that, owing to the abundant supply of nerves which this viscus receives, chiefly from
the ganglionic system, it possesses a considerable share of the vital influence of the
body ; that this influence is chiefly exerted in giving rise to its organic motions, and in
producing its specific secretions, and that, from the circumstance of so large a propor-
tion of its ganglial nerves being distributed on its arteries, the juices which they se-
crete or exhale are imbued with an emanation or some certain manifestation of this in-
fluence, which is the principle agent in the digestive process. Hence the relation be-
tween the states of this influence, and the quantity and quality of the gastric juices must
be very intimate; and it seems to be owing to this intimacy, that the primary agent has
been hitherto overlooked in the more evident and grosser materials with which it is al-
lied, and by means of which it operates. The varying conditions of the function of di-
gestion in health and in disease, and the close connexion between it and every manifes-
tation of the body, eminently support this view of the subject ; and, independently of
the direct evidence fnrnished by the very interesting experiments of Drs. Wood and
Sillar, of Liverpool, many collateral proofs may be adduced in its behalf.

H. Of Vomiting. W^hilst we attribute the digestive process chiefly to the vital influ-
ence proceeding from the ganglial system, we do not overlook the fact that that part of
this system supplying the stomach is acted upon, to a certain extent, through the me-
dium of nerves communicating with, and of others given off from, the cerebro-spinal
system, which may reasonably be supposed to perform the functions belonging to their
respective sources.

It is owing to this provision, when the stomach is irritated, and when its organic con-
tractility is inordinately excited, that its sensibility is also roused — the influence is pro-
pagated to the sensonmn, and contraction of the abdominal and respiratory muscles is
also produced, — which contracting co-operates with that of the stomach itself, in giving
rise to vomiting. Magendie has inferred from his experiments, that it is only the con-
traction of the abdominal muscles and diaphragm which produces vomiting, and that
the stomach has no share in the act. This physiologist, on this, as on other occasions,
has not taken into account the various sources* of error to which experiments on living
animals are liable. He has not sufficiently considered, or calculated upon, the unna-
tural positions in which such experiments place the animals experimented upon, and
thus derange their natural operations. Stricter and more comprehensive views of the
subject show that, whilst former physiologists have erred in attributing the act of vo-
miting too exclusively to a sudden contraction of the stomach, Magendie and his disciples
have been equally to blame in adopting too implicitly the more tangible phenomenon
of some inconclusive experiments. The steps in this'process appear to be the follow-
ing:— an irritating cause rouses the organic insensibility of the stomach, and gives rise
to a considerable contraction of its muscular coats. This exalted state of its organic
sensibility and contractility excites, in consequence of the intimate nervous communica-
tion between the stomach on the one hand, and the diaphragm and abdominal muscles
on the other*, the action of the latter, which, from vicinity of situation, perform so im-

* Through the medium of the eighth pair of nerves, and of the branches of the gan-
glia! system which joins the spinal nerve?*

24 APPENDIX.

portant a share 4n the act. Hence it follows, that neither the contraction of the sto-
mach alone, nor that of the muscles only, can be sufficient to give rise to the act of vo-
miting. It would seem that so intimately connected are inordinate irritations of the
stomach with the action of the diaphragm and abdominal muscles, owing to the anato-
mical relations of the ganglial system with the eighth pair of nerves, and with those of
the spinal cord, that the one can never lake place, under the ordinary state of the sys-
tem, without being followed by the other, and giving rise to the act under considera-
tion. The nausea which precedes vomiting, is merely the sensible impression made by
the irritating cause on the nerves of the stomach, which impression, if sufficiently exalted,
terminates in the act in question. When this step of the process is about to take place,
the diaphragm is the first to contract in a spasmodic manner ; indeed, the irritation of
the stomach having excited the diaphragm, the former is struck by the latter against the
abdominal muscles, and at the instant when the diaphragm relaxes, the abdominal mus-
cles re-act and impel the stomach against the relaxed and ascending diaphragm, which,
in consequence of this state, readily allows the contents of this viscus to be impelled, by
the concussion of the abdominal muscles, through the cardia into the oesophagus. That
the diaphragm is the first to contract, and that it is the first to relax, are shown by at-
tending to the steps of the process, and by the fact that the stomach could not empty
itself through the cardia, if the diaphragm were to continue in a state of contraction.
It will therefore appear that the action of the stomach is at its acme when the abdominal
muscles re-act and consummate the process ; and that, whilst the diaphragm commences
the operation, the abdominal muscles are chiefly efficient in perfecting it. It must be kept
in recollection that both do not contract at the same time. The violent action of the latter
impels the stomach, and, indeed, the superior viscera of the abdomen, so forcibly upon
the relaxed diaphragm, and encroaches so much upon the cavity of the thorax, the whole
respiratory muscles being then relaxed, that the lungs are at the time considerably pres-
sed upon? and this pressure is farther increased by the ascent of the contents of the
stomach through the_cesophagus. Hence it is that vomiting always promotes the dis-
charge of secretions which have accumulated in the bronchia^.

HI. Of Human Rumination,— -The author has adverted to this subject in the text in a
very brief manner. As this affection is more frequently amongst individuals apparently
enjoying their usual health than is generally supposed ? and as many who habitually
rumiftate consider it to be only a step of the digestive process, — which is certainly the
truth as far as respects themselves, — we shall enter more fully into the subject, as it
has more than once fallen under our observation.

Under the usual circumstances, rumination commences from a quarter of an hour to
an hour and a half after a meal. Immediately upon the commencement of this act, a
slight sensation of fullness may be felt at the cardia, when the attention is particularly
directed to it, that leads to a deeper inspiration than usual. So soon as the act of in-
spiration is completed, and while the muscles of the glottis remain fixed, a bolus of the
unchanged aliment rises rapidly from the stomach, with the first effort at respiration,
at the moment when the diaphragm has just relaxed, and the re-action of the abdomi-
nal muscles commenced. But expiration does not take place until the alimentary ball
has passed completely into the mouth, as the glottis remains closed until then : upon
this having taken place, expiration is immediately effected ; and so rapidly does respi-
ration succeed to the regurgitation of the alimentary bolus, that the latter (unless when
the attention is closely applied to the subject,) appears as part of the expiratory act.

The ruminating process is never accompanied, at any time, with the smallest degree
of nausea, nor any pain or disagreeable sensation. The returned alimentary bolus is
attended with no unpleasant flavour, is in no degree acidulous, and is equally agreea-
ble, and is masticated with additional pleasure, and with much greater deliberation
than when first taken.

The whole of the aliments taken at one meal is not returned in order to undergo this
process, but chiefly the part that has been insufficiently masticated.

The more fluid portions are not always returned, unless along with the more solid or
imperfectly masticated parts. When, however, the stomach is distended by a large
meal, the fluid contents are frequently returned, and subjected to this process

This affection may be considered as being passively under the control of the will ;
and, although it sometimes takes place when the individual is nearly unconscious of
the process, yet it never occurs when ttie mind is incapable of being acted on hy ex-
ternal impressions received by the senses. Thus, if at any time, from previous fatigue,
and the concentration of the organic nervous energy towards the digestive organs,
sleep be induced immediately after a full meal, this affection does not take place : but
flatulence, acrid eructations, &c. usually supervene, and continue for some time, in

OF DIGESTION, 25

consequence of the vital energy and gastric juices being insufficient to the production
of the requisite changes on the ingesta retained in a state of imperfect division.

With respect to the nature of human rumination it appears evident that it only takes
place when the vital energy of the assimilating organs is greatly diminished ; conse-
quently, when the activity of the stomach, both as it relates to its'muscular action and
secreting functions, is equally lessened ; this is apparent from the circumstance, that
aliments, if they be taken even in very moderate quantity, are not properly digested by
ruminating individuals when they are retained without having been re-submitted to
mastication. Connected, also, with debility of the stomach, an increase of its sensibi-
lity, which it derives from the distribution of the eighth pair of nerves, seems to*be
present. Both these states of this organ render it more necessary that the ingesta
should undergo a perfect mastication and thorough admixture of the salivary juices, in
order to suit it to the weakened functions of the stomach.

Under the circumstances of deficient vital energy of the stomach, of increased sensi-
bility, and diminished secretion, a small portion only of food can be digested ; yet it is,
nevertheless, generally taken in considerable quantity by ruminating* individuals. In
this case, that portion of it most favourable to the admixture having combined with the
gastric juices, and being, by the natural action of the stomach, conveyed to the pylorus,
the undigested portions and those which have been imperfectly masticated, must either
remain at the cardiac extremity, or be propelled there by the usual action of the viscus,
where they excite its organic sensibility, and, in consequence of intimate nervous con-
nection, the co-operation of the muscles of respiration, especially of the diaphragm and
abdominal muscles, and thus give rise to the ruminating process.
fin its performance, the organic contractility of the stomach can do no more than by au
elective process (soon to be explained) place the aliments about to be returned in a
situation, in respect to the cardia, favourable to the excitation of the organic sensibility
of this organ, and to its ready regurgitation and propulsion along the oesophagus. As
soon as the demand is made upon the sensibility by the situation of the alimentary
bolus, the par vagal class of nerves is excited to action, and a full respiration is effected,
as has been described. The introduction of the bolus into the cardiac extremity of the
oesophagus, may be considered as effected by the ordinary contractility of the stomach ;
perhaps sympathetically heightened at the moment by the re-action of the abdominal
muscles ; while, at the same time, the diaphragm has just undergone relaxation, in
which the cardia may, from intimate nervous communication, also participate, and thus
facilitate the ascent of the alimentary ball in the cesophagus, which immediately con-
tracts behind it from the irritation produced by its passage, and the bolus is thus con-
veyed to the mouth.

That relaxation of both the diaphragm and cardiac extremity of the cesophagus ac-
tually exists at the moment, although the glottis still remains closed, appears confirm-
ed, both by the period of the respiratory act at which this process is produced, and by
the circumstance that, when any restraint is exercised over this affection, it is princi-
pally by means of exciting the diaphragm to a frequent and continued action, when the
premonitory sensation is felt at the cardia.

The influence of the will appears to be requisite, since the process is interrupted
during sleep. But this influence is only passively engaged in the production of the ru-
minating act, by bringing about the co-operation of the respiratory organs.

The elective process exercised by the stomach in this affection, is similar to that
which it exerts in periods of health, which may be considered as relative to the degree
of digestive energy, and to the comparative states of comminution and insalivation, in
v/hich the various ingesta may enter the stomach.

During the process of digestion, contraction takes place irregularly and under various
situations in this organ, according as different portions of the longitudinal or circular fi-
bres may act ; this operates in producing a degree of arrangement in the aliments ;
and, as the gastric juices combine with the more soluble portion of the food, especially
that situated towards the mucous surface of this organ, which, when duly effected, is
conveyed by the varying organic contractility of the muscular coat, towards the pylo-
rus ; while a successive and concentric stratum comes in contact with, and, if in a per-
meable state from its previous comminution and admixture with the salivary juices, is
soon penetrated by the secretions of this organ ; and even the central mass not unfre-
quently is obliged to yield its more fluid parts to the exterior layer, when there is a de-
ficiency of fluids in the alimentary contents. Hence the not unusual necessity for drink
that takes place as digestion proceeds.. In the course of this process, as it is the result
of the healthy functions of the organ, the chyme in contact with its mucous surface i.s
conveyed in a direction from the cardia to the pylorus. But, if the propagation of th-
digested contents towmls this extremity of the organ proceed faster than it can pa?3

D

through into thfe duodenum, thfe accumulation of cuyme that consequently fakes plac£
in that direction, tends to propel the less soluble portions towards the cardia ; where,
according to the state of the organ, it may produce cardialgia, acrid eructations, or even
rumination.

In the debilitated state of the stomach, and consequent deficiency of the secretions,
digestion can be perfectly performed only when the aliments are presented to it in
small quantity, and in a favourable state of complete comminution and intermixture
with the salivary juices, If, however, in this condition of the organ, the food is con-
veyed rapidly into it, possessed of neither of these requisites, so as to produce sudden
distension, a re-action of this viscus upon its contents takes place ; and, as the imper-
fectly masticated food constitutes the greater portion of the ingesta, there is abundance
present to be returned into the cardia and to be regurgitated, while there is a defi~
ciency of aliment in a fit state to combine with, or to be operated upon, by the gastric
juices ; this when converted into chyme, is rapidly conveyed to the other extremity of
the organ, by the re -action of the muscular coat, arising from undue distension and the
stimulus of solid contents. Thus a double effect is produced by the healthy organic
contractility of this viscus, when in a weakened state, and yielding a diminished quan-
tity of the usual fluids, which state, indeed, rnay be considered as constituting this pecu-
liar affection, — namely, the part of the aliment which is dissolved by the gastric juices
is conveyed toward the pylorus, whilst the tonic action of the stomach tending to di-
minish its capacity, pushes the less comminuted and indigestible portions of food into
the unresisting cardia ; whence they are returned, as we have described, in order to
undergo a second comminution and intermixture with the salivary juices ; after which
they are in a fit state to be conveyed to their destination along the mucous surfaces,
with the juices of which they combine, and thus permit a central portion of the mass to
return and undergo a similar process.

Of the Influence ofthefineumo-gastric Nerves in Digestion*
Note L.

The experiments of Dr. Phillip, although they by no means warrant the inferences
•Which he deduced from them, show that the eighth pair of nerves conveys the influ-
ence of the cerebro-spinal system to the stomach, and re-intbrces and stimulates tha
vital energy bestowed on it by the ganglial system.' This conclusion is farther sup-
ported by the experiments lately performed at Paris by Breschet, Edwards and
Vavasseur. The inferences, which these physiologists have drawn from their experi-
ments, are —

1st. Simple section of the pneumo-gastric nerves in the region of the neck, without
loss of substance, and without separating the cut extremities, does not prevent diges-
tion from taking place, but merely retards it in an evident manner.

2dty. Section of these nerves, with loss of substance, diminishes considerably, and
much more than simple section, the digestive action of the stomach, but it does not ap-
pear to abolish it completely.

3dly. Section, or destruction of part of the spinal marrow, or removal of a portion of
the brain, acts in the same manner on the changes which the food undergoes in the sto-
mach.

4thly. Narcotics, administered so as to produce coma, equally dimmish the energy
of the digestive powers.

Sthly. It results, consequently, that every thing which diminishes the amount of ner-
vous influence, transmitted to the stomach, weakens the digestive action.

6thly, and finally. When digestion is almost completely suspended by the section,
\vith loss of substance, of the pneumo-gastric nerves, the digestive action of the sto-
mach may be re-established, and the food contained therein be converted into chyle, by
means of the galvanic influence, with almost as much rapidity, and as perfectly, at least
in appearance, as under ordinary circumstances. {Archives generates, de Medicine,
.Aw*. 1823.)

When the connexions of the different orders of nerves which supply the stomach arc
considered, and the intimate relation consequently subsisting between this organ and
the centres to which these nerves respectively belong, it cannot for a moment be
doubted that the interruption of the channel, through which this connexion takes
place, should be followed by a deranged stale of the functions depending thereon. Al-

OF I'NEUMO-GASTRIC NE&VES IN DIGESTION. $fi

lowing that the stomach derives its chief and its more vital influence from the ganglial
system, and an additional and a modified influence from the cerebro-spinal system, the
latter exciting- or otherwise influencing the former, and granting that respiration is re-
quisite to the energy of both, it surely cannot be for a moment doubted, that an
interruption either of the one or the other should occasion, owing both to the
defect of a requisite influence and to the injury done to the system generally by
the experiment, a very considerable derangement of the functions of this organ. We
perceive that slighter causes, such as those mentioned at p. 77 of the text, will produce
a much greater disorder of the actions of the stomach than the formidable operation of
division of the eighth pair of nerves — formidable not only as respects its effects upon
digestion, but as regards its influence on the function of respiration, and upon the body
generally — can it therefore be a matter of surprise, that destruction of, or interruption
to, a wonted and requisite influence should be followed by marked effects upon the
organ which such influence is destined to actuate ? Because the influence conveyed
by the nerves from the cerebro-spinal sysem affects the functions of the stomach or
an interruption to it disorders them, can it therefore be logically concluded that this
viscus derives its functions from that source, and that none of them acknowledges any
other origin ? Because these particular nerves are ready conductors of galvanism, and
because galvanism excites the. natural actions of the digestive organs, ought it therefore
to be concluded, that the natural office of these nerves is to convey and distribute this
agent, or that the vital influence with which these organs are endowed, is identically
the same as it ? We think that no one can be justified in answering these questions in
the affirmative, by the evidence which these experiments afford. From a careful con-,
tnderation of the phenomena which they furnished, and from the few experiments
\vhich we have made with this active agent, we conclude, — 1st.- That the functions of
the stomach depend chiefly upon the supply of ganglial nerves, which its vessels, mus-
cular fibres, and secreting surface receive. 2d. That the pneumo-gastric nerves con-
vey the influence of the cerebro-spinal system to this organ, which influence re-inforces
that which it receives from the ganglial system, or proves a stimulus to it. 3d. That
this latter influence is more requisite to the perfect performance of the functions of
the stomachj the older the animal is, and the higher we rise, in our observations
amongst the more perfect animals. 4th. That when this influence is interrupted, in a
more or less complete manner, in its course to the stomach, its place may be, in some
measure, supplied by galvanism, which seems to excite the proper or vital influence
which the organ receives from the ganglial system. 5th. That we have no proof of
galvanism acting otherwise in the process than as a stimulus to properties already pos-
sessed by the organ on which it acts, and that it acts in those experiments through a
medium to which the organ is habituated, and in a great measure dependent for a na-
tural excitement. 6th. That although galvanism excites the functions of the stomach,
for a time, we have no evidence of its continued power in promoting them, during a
protracted interruption of either the one species of nervous influence or the other; it
even appears probable that the continued operation of this agent, although like other
powerful stimuli it at first actively excites the natural functions of the part on which
it acts, would, nevertheless, exhaust them, more especially if they were not supplied
from their natural sources. 7th. That, as we have no comparative trials of the effects
of other powerful stimuli, under similar circumstances to those in which galvanism has
been employed, conclusive inferences cannot be drawn respecting the extent of influ-
ence of that agent ; at least none that can oppugn the above positions, they may, and,
very probably, they will confirm them, and show that the activity of galvanism in exci-
ting the animal operations, merely results from the properties of this agent enabling it
to act, through channels which convey a natural and a requisite influence, in a more
energetic manner than other excitants which we can employ in our experiments. Rea*
soning, indeed, from what we already know of the properties of galvanism, and from
its operations upon inorganized matter, we should be led to expect more energetic ef-
fects from it upon the animal system, than from any other agent which we have under
our control.

28 APPENDIX.

Of the Intimate Structure and Functions of the Liver.

Note M.
The very minute researches of Dr. J. M. -Mappes, of Frankfort on the Maine, on the

rnately it will itself pass out of those vessels. If the liver be now examined, either by
dissecting of the peritoneum, or cutting or tearing the liver, two structures will be ob-
served ; the one granulated, forming convolutions, now resembling those of the intes-
tines, and now branching in other forms ; flattened and yet rounded, dense and of a yel-
low colour, and about a quarter of aline in diameter — the other a cellulo-vascular struc-
ture, of a brown colour, which fills up the rounded spaces or oblong fissures, of from a
quarter to a half a line in diameter, which separate the convolutions from each other.
These strictures are well shown, if water, in which cinnabar has been diffused, be thrown
into the hepatic veins ; for the cinnibar is precipitated on the sides of the vessel, and
the water passes by the vena portae. Between the convolutions are found triangular and
somewhat broken openings, which communicate with each other by little chinks.
Some of these contain twigs of the hepatic vein ; in the others, and especially where
the chinks are traced to a great depth, and where the vessels form larger trunks, three
vessels are seen together, a large one belonging to the hepatic vein, and two others, of
a smaller diameter, belonging to the artery and the hepatic duct.

" If the hepatic vein be excepted, the other vessels form branches like a tree, as in
the rest of the body. The artery, however, gives the most branches ; apparently, be-
cause they surround, like a capillary net-work, the parietes of the vena ports, to which
purpose they seem to be particularly destined : although some brandies penetrate to
the surface of the liver, and are distributed on the peritoneum — but without forming a
net-work, as in the former case. The ramifications of the hepatic artery and the hepatic
duct are always strictly united together ; and, in accompanying the larger branches of
the vena portae, they do not intertwine at the two opposite sides of the latter vessel.

" The large branches of the hepatic duct divide at an acute angle ; but the ramifica-
tions divide at right, or even obtuse angles. It is these latter short and loose twigs which
form the parallel ranges of holes, which are seen by cutting1 the liver in the direction
of a branch. These holes are the orifices of vessel, as is seen by injection or by dis-
secting the twigs : they cannot, therefore, be confounded with the little dimples which
are seen on the internal parietes of the largest hepatic trunks. All the ramifications of
the hepatic trunk, indeed, when cut, present a gaping, firm opening, like an artery ;
whilst the cut orifice of the vena portse, which accompany them, are always in a col-
lapsed state.

«< The duct ramifies something like the vein. The short and thick trunks divide into
branches, and form a crowd of smaller and looser twigs, which embrace the grains of
the granular substance above described, but apparently without penetrating the sub-
stance of them. Hence, these grains are somewhat separated from each other, and they
in some degree compress the cellulo-vascular substance, without, however, giving any
of their colour to the latter, which is only traversed by some injected vessels.

" The parietes of the artery, the vena ports, and the hepatic duct, do not adhere to
the substance of the liver ; but are separated from it, as may be seen by the microscope,
partly by a uniform gelatinous, matter, and partly by an extension of the cellular mem-
brane, which composes the capsule of Glisson. The hepatic vein, on the contrary, ad-
heres intimately to the granulated substance ; it also follows without variation, the lat-
ter in its distribution, and the smallest branches penetrate between its granulations.
These facts prove the intimate relation which exists be ween (he vein and the granular
substance : whilst the artery and vena portse ramify together in the cellulo-vascular sub-
stance, and on the surface of the principal circumvolutions of the granulated substance;
atid the hepatic duct, the twigs of whicli are averted from each other, seems to hold a
relation with both orders of vessels.

" If a single hepatic vessel be injected, the injection will only pass to the part to
M'hich that braivch is distributed ; on the contrary, water passes rapidly and easily from

* Journal Complernentairc du Dictionnaire des Sciences Medicales* No, 46 Mai, 1822.

INTIMATE STRUCTURE AND FUNCTIONS OV THE LIVER. 29

the vena porta to the hepatic vein, and rice versa. Wax, however, rarely passes, and
the hepatic duct is never filled either from the vena portee or -hepatic vein."

From these facts M. Mappes is led to consider the granular substance to be the se-
creting part of the liver, around which the vessels are grouped as the conducting1 and
preparatory apparatus. The more intimate connexion which it holds with the radicles
of the hepatic vein has induced him to presume that the bile is more probably separated
by it, from the blood which had actually arrived within these radicles, than from that
which circulates in the extreme ramifications of the vena portae. This particular sub-
stance appears also to M. M. to form the basis of all the glands, and to be of a peculiar
nature, modified according to the functions which nature has imposed on it. He fur-
ther supposes, that in all glandular structures there exists an intermediate substance,
between the extreme ramifications of both orders of vessels, which holds a more inti-
mate relation with the changes induced in the blood, than the other parts through which
it circulates. This substance he conceires to be of a mucous character, and to form the
basis of the granular part of the liver and other glands, in which the vessels terminate
and commence, and which, he thinks, is entirely appropriated to the particular function
and destination which the gland is intended to fulfil. In proof of this he quotes Dcellinger.
who has adopted a similar opinion. M. Mappes, in an analysis which he offers of Ey-
senhardt's investigations respecting the anatomy of the kidney, concludes that the inti-
mate structure of this organ and the liver is in many respects" similar.

Although it is generally agreed amongst physiologists that the secretion of the bile
takes place in the granular structure of this visc'us, it is by no means so generally allowed
that the secretion is furnished by the blood of the vena portse. Bichat contended that
the bile is secreted from the hepatic artery, and adduced numerous analogies in support
of the opinion. More recently M. Magendie has considered it to be formed, at the
same time, from the blood of both the portal and arterial systems.

It seems to us most probable, reasoning from the facts ascertained respecting absorp-
tion, that the blood which circulates in the vena portae, being that which is possessed
of the venous characters in the highest degree, and which, moreover, has a considera-
ble portion of new materials — the products of digestion and absorption — poured into it
before it reaches the liver, undergoes there those changes which are necesssary to a
perfect assimilation of these materials, and to the future offices which the blood itself
has to perform in the animal economy ; and that, in the course of, or in addition to,
these changes, the blood of the vena portce has certain of its elements eliminated from
it, the elimination of which is requisite not only to the accomplishment of these chan-
ges, but also to the production of a secretion which perform certain offices in the pro-
cess of digestion. This view of the subject is supported by the facts, — 1st, that those
elements, of which the bile is composed, abound the most in the blood of the vena por-
tx, and that, if they were to remain in the blood circulating throughout the body, con-
sequences subversive of its healthy existence would rapidly supervene;--2d,that the por-
tal ramifications are plentifully supplied with the ganglial nerves, which we have shovvu
to be the source whence the blood-vessels derive their vitality and functions, and the
origin of those changes which the fluid circulating in them experiences ; — and 3d, that
the divisions themselves of the vena portse, receive a much greater supply of arterial
capillaries from the arteria hepatica than is observed with respect to any other vein in
the body.

From anatomical investigation, therefore, — from numerous experiments bearing1 in-
directly on the subject, and from pathological observation, we infer, that the blood
which returns from the digestive tube, from the spleen, &c. [having been shown to
contain a considerable portion of absorbed materials, some of them of a more or less
heterogeneous description, others of them more or less animalized ; and, moreover, that
certain of the elements or constituents of the blood, requiring to be eliminated from
the system, are there in an increased and hurtful quantity, if they were allowed to re-
main in it, undergoes in the liver most important changes ; that these changes are of
two kinds, the one referring to the assimilation of the less animalized materials which
the blood may contain, the other to the elimination of the heterogeneous, hurtful, or
effete elements which may circulate* in it ; that these are produced through the me-
dium of the vessels and granular structure of the liver, by the vital influence with which
both are endowed from the ganglial nerves supplying them ; that these changes are per-
fect or defective, in proportion as that influence is perfect or defective, provided that
the structure of the parts- — the instruments of this influence, be not deranged ; and that
as the vital functions of the organ, depending upon the sources pointed out, may vary
very greatly; and, as the structure of one or more of the parts constituting the organ
may consequently become deranged, the operations of the liver may be thus disorded
:u a simnle o? more or less complex manner.

30 APPENDIX.

Oftte Uses of the JBile. Various opinions have been entertained by physiologists re-
specting the purposes of the bile. " Some have supposed that the secretion of bile is
merely excrementitious ; others that the bile is intended to stimulate the intestine, and
to produce a ready evacuation of the faeces ; and another opinion has been, that the
bile is poured out into the duodenum, that it may be blended with the chyme, and by
producing chemical changes in it, convert it into chyle. The situation of the liver, con-
nected as it is in every instance with the upper part of the alimentary canal, is unfa-
vourable to the first of these hypotheses ; but the last is rendered very probable by the
circumstance of chylincation taking place just at the part where the bile flows into the
bowel."

In order to arrive at some satisfactory conclusion on these points, Mr. Brodie applied
a ligature round the choledic duct of an animal, so as completely to prevent the bile
entering the intestine, and then noted the effects produced on the digestion of the food
which the animal had swallowed, either immediately before or immediately after the
operation. The experiment was repeated several times, and the results were uniform.
Before he describes these results, he remarks, that the " application of a ligature round
the choledic duct is easily accomplished, and with very little suffering to the animal ;
so that any derangement in the functions of the viscera, which follows, cannot reasona-
bly be attributed to the mere operation. The division of the stomachic ropes, or ter-
minations of the eighth pair of nerves on the cardia of the stomach, and the ligature of
the whole extremity of ihe pancreas, are operations of much greater difficulty : yet it
has been ascertained that neither of these at all interfere with the conversion of the
food into chyme, or that of the chyme into chyle-"

" When an animal," Mr. Brodie proceeds to state, « swallows solid food, the first
change which it undergoes is that of solution in the stomach. In this state of solution
it is denominated chyme. The appearance of the chyme varies according to the nature
of the food. For example, in the stomach of a cat the lean or muscular part of animal
food is converted into a brown fluid, of the consistence of thin cream ; while milk is
first separated into its two constituent parts of coagulum and whey, the former of
which is afterwards redissolved, and the whole converted into a fluid substance, with
vexy minute portions of coagulum floating in it. Under the ordinary circumstances,
the chyme, as soon as it has entered the duodenum, assumes the character of chyle.
The latter is seen mixed with excrementitious matter in the intestine ; and in its pure
state ascending the lacteal vessels. Nothing like chyle is ever found in the stomach j
and Dr. Prout, whose attention has been much directed to the chemical examination of
these fluids, has ascertained, that albumen, which is the principal component part of
chyle, is never to be discovered higher than the pylorus. Now, in my experiments,
which were made chiefly on young cats, where a ligature had been- applied so as to ob-
struct the choledic duct, the'first of these processes, namely, the production of chyme
in the stomach, took place as usual ; but the second, namely, the conversion of the
chyme into chyle was invariably and completely interrupted. Not the smallest trace
of chyle was perceptible either in the intestines or in the lacteals. The former contained
a semi-fluid substance, resembling the chyme found in the stomach with this difference,
however, that it became of a thicker consistence in proportion as it was at a greater dis-
tance from the stomach ; and that, as it approaches the termination of the ileum in the
csecum, the fluid part of it had altogether disappeared, and there remained only a solid
substance, differing in appearances from ordinary fxces. The lacteals contained a trans-
parent fluid, which I suppose to have consisted partly of lymph, partly of the more fluid
part of the chyme, which had become absorbed.

" I conceive that these experiments are sufficient to prove that the office of the bile
is to change the nutritious part of the chyme into chyle, and to separate from it
the excrementitious matter. An observation will here occur to the physiologist. If
the bile be of so much importance in the animal economy, how is it that persons occa-
sionally live for a considerable time, in whom the flow of bile into the duodenum is in-
terrupted ? On this point it may be remarked, 1st, That it seldom happens that the
obstruction of the choledic duct from disease is so complete as to prevent the pas-
sage of the bile altogether; and the circumstances of the evacuations being of a white
colour may prove the deficiency, but does not prove the total absence of bile. 2ndly,
That in the very few authenticated cases which have occurred, of total obliteration of
the choledic duct in the human subject, there has been, I believe, always extreme
emaciation, showing that the function of nutrition was not properly performed. 3dly,
That the fact of individuals having occasionally lived for a few weeks or months under
these circumstances only proves that nutrition may take place to some extent without
chyle being formed. In my experiments I found that the more fluid parts of the
chyme had been absorbed, and probably this would have been sufficient to maintain
life during a limited period of time."— (Journal of Science and the *%rts, No- 28.)

OF THIS STRUCTURE AKD FUNCTIONS OP THE SPLEEN. 31

Dr. Stearns of New York, is of opinion that the gall-bladder is not passive in the
reception of the bile, and that it is not a mere receptacle for this fluid. He supposes
that the cystic duct acts as an absorbent, selecting1 from the bile in the hepatic duct, ita
more active ingredients, which are carried into the gall-bla ider, where they remain
until "some peculiar irritation" of the mouth of the common duct, by the passing
chyme or by some other stimulating cause, solicits its discharge, in a gradual manner,
for the purpose of purging the intestines. In support of this opinion he refers to the
experiments of Dr. Douglass, of the same city, who found that the bile which passed
clirectJy from the hepatic duct into the intestines was bland and harmless, and was
mixed with the chyme, and thus seemed to aid, as shown by the very conclusive ex-
periments of Mr. Brodie, in the formation of the chyle, and of the new materials for
the nourishment of the body ; whilst the bile found in the gall-bladder was always bit-
ter, pungent, and viscid.

These properties, however, of the cystic bile may supervene without any election
being exerted by the cystic duct in the process ; for if we suppose, what is most pro-
bable, that during the empty state of the duodenum the bile flows into the gall-bladder,
where its more bland and fluid portions are removed by the numerous absorbent ves-
sels with which the gall-bladder and its ducts &re provided, and where, during its
retention, its elements combine in such a manner as to modify the characters of the se-
cretion, and to render them very different from those which it evinced immediately
after its formation, we have a sufficient reason for the more pungent qualities, of cys-
tic bile. It seems by no means unlikely, therefore, that the change takes place in the
bile itself within the gall-bladder, and that it is promoted by the temperatui-e and vital
influence of the system.

With respect to Dr. Stearns's opinion, that the gradual flow of the cystic bile into
the intestines serves the purpose of a gentle purge or stimulus to their functions, it ia
by no means new ; but we have no more proof that it acts the part of a purge, than
that it performs the office of an astringent. How is it, if this opinion be correct, that
diarrhoea, or a lax state of the bowels, is so often observed during the interruptions of
the biliary secretion, and especially of the cystic bile ?

After the full detail of the results of Mr. Brodie's con elusive experiments we need
not.state at greater length modern views upon the subject. In the note upon the function
of respiration, we will briefly notice some peculiarities connected with the functions of
the liver and conditions of the bile.

Of the Structure and Functions of the Spleen*
Note N.

Although considerable attention has been paid to the physiology of the spleen, yet
its functions are but imperfectly understood. They have, indeed, been variously ex-
plained by philosophers, but all have erred, chiefly in endeavouring to assign to it one
definite function only, which they consider it to perform under all the circumstances
which influence the body. Thus, Malpighi, Haller, Blumenbach, Richerand and
Fodere, imagine this organ to be subservient in its functions to those of the liver.
Hewson believed it to be destined to the elaboration of the globules of the
blood. Tiedemann, and Gmelin are of opinion, that it is intimately Connected with
the absorbent system, and that it assists the process of sanguifaction. Haighton and
Moreschi, consider that it is subordinate to the stomach in the process of digestion;
and many pathologists believe that it permits, in consequence of its peculiar texture,
accumulations of blood to take place within it during certain stages of disease, and
that it thus prevents more vital organs from suffering injury to which they would other-
wise be liable. To us, however, it appears more rational, and certainly more consis-
tent with the operations which characterize the economy of the more perfect animals,
to view the functions of this organ as intimately relating to those which the absorbent,
circulating, and secreting systems perform, and as including several of the operations,
just specified, to a greater or less extent, according to the influence to which the body
is subjected.

In order to learn the nature of the offices which the spleen performs in the animal
economy, it ought to be our first object to ascertain correctly its structure ; that is,
however, a matter of gveat difficulty. The attention of anatomists has lately been par-
ticularly directed to the subject, and Home, Heusinger, and Hopfengaertner, have been

3& APPENDIX,

assiduous in that investigation, without, however, determining the much disputed point,
whether or no this viscus possesses a proper or glandular structure, or is it simply a
minute and infinite interlacement of arteries, veins, and lymphatics. Sir Everard
Home concludes from his researches, that, " it consists of blood-vessels, between which
there^isno cellular membrane, and the interstices are filled with serum, and the colour-
ing matter of the blood from the lateral orifices in the veins, when these vessels are in
a distended state ; which serum is afterwards removed by the numberless absorbents
belonging- to the organ, and carried into the theoracic duct by a very large absorbent."
Sir Everar;' considers " the spleen, from this mechanism, to be a reservoir for the super-
abundant serum, lymph globules, soluble mucus and colouring matter, carried into the
circulation immediately after the process of digestion is completed.

M. Beclard, (additions to the anat. genewle of Bichat,) has given an opinion respect-
ing the structure of this viscus, which appears to be the most correct yet offered. He
considers that it belongs to the class of erectile tissues, and that its structure results
from a peculiar arrangement of arteries and veins similar to that which is found in the
penis, the clitoris, and female nipple. M. B. thinks, that the spleen very nearly resem-
bles the cavernous body, of the penis, both in structure and in its phenomena ; and he
considers it not only to consist of erectile tissue, but to be also the seat of a species of
erection more or less similar to that of the cavernous body. This viscus, he argues, pre-
sents an actual motion of expansion and contraction, and he adduces the three following
circumstances under which this takes place. 1st, In experiments ; when the course of
blood in the splenic vein is arrested in living animals, the spleen swells, but returns to
its former dimensions as soon as the circulation through the vein is restored. 2d, In
diseases ; the paroxysms of intermittents are accompanied with an obvious enlargement
of this viscus, which subsides as soon as the paroxysm is over. 3d, A similar phenom-
enon takes place during digestion. The lateral openings of the veins, noticed by Sir
Everard Home, seem to confirm the views of M. Beclard respecting the dilation and
frequent inosculations of the venous radicles in this viscus, which are common to it and
the other erectile tissues. (See the note in the appendix on the organs of Generation.)

With respect to the functions of the spleen we will only adduce those views which
possess claims to a favourable notice.

C. H. Schmidt, (Comment. dePathol Lienis.) considers that its vasa brcvia contribute
to nourish and strengthen the stomach; and that, as the blood of dogs deprived of the
spleen, is found to run speedily to putrefaction, it is concerned in, the preparation and
assimilation of the elements of the blood, and that it performs an office to the liver
analogous to that which the lungs fulfil with respect to the heart.

Professors Tiedemann and Gmelin (Versuche uber die Verriclitnng der MHz, &c.*\ con-
clude, from their investigations on this subject, 1st, That the spleen is an organ closely
connected with the lymphatic system. This is shown by its being restricted to those
animals which possess a separate absorbent system, by the number of its lymphatic
vessels, and by the circumstance of the spleen of the turtle being similar to a mesen-
teric gland. 2nd, That a coagulating fluid is secreted in it from the arterial blood, is
taken up by the absorbents, and carried into the thoracic duct. This fluid or lymph,
they remark, was seen not only by them, but by Hewson ; and they conclude, that the
formation of it is the only means by whic"i it is possible to account for the use of the
great quantity of arterial blood which flows into the spleen. In answer to the ques-
tion,—by what means this coagulable lymph passes into the absorbents ? they reply, —
either there are, in the substance of this organ, particular gland-like bodies, and small
spaces or cells, which several anatomists say they have remarked, in which the fluid is
secreted and taken up by the absorbents, or the finest branches of the arteries in the
spleen pass immediately'into the absorbents, and by this means some parts of the arte-
rial blood reach the absorbents. From a consideration of all the facts obtained by
themselves and former investigators, they infer that a connexion subsists between the
splenic arteries and absorbents, either directly, or indirectly, by means of cells. The
secretion of this reddish coagulating lymph from the arterial blood takes place, in their
opinion, from the nerves h^ing excited, particularly during digestion : and consequent-
ly, by the plentiful secretion, the course of the blood is carried forward in the spleen,
which by this means is reduced in size. 3d, That this secreted coagulable lymph, when
conveyed into the thoracic duct is intended to render the chyle similar to the,f blood.
They consider this inference to be proved by at least two circumstances ; 1st, That
this change actually takes place, for the chyle of the thoracic duct differs from the
chyle of the mesenteric vessels, by a closer resemblance to perfect blood : 3d, That
when this coagulable matter was by any means prevented from reaching the thoracic
duct, this change did not take place. Amongst other proofs which Professor Tiede-
mann and Gmelin adduce in support of these circumstances, they show that the chyle
taken from the absorbents of the intestinal canal, before they had passed through the

OF THE INTESTINAL CANAL, &c. ,}3

mesenteric glands, is always white and has no tinge of red, and either undergoes no
coagulation, or does so very feebly and slowly. The same fact has been previously
shown by various anatomists, and similar appearances to those which are now to
be noticed have been remarked by Dr. Prout. Professor Tiedemann and Gmelin al-
ways observed that this fluid, when it is taken from the absorbents which had passed
out of the mesenteric glands, is redder, and coagulates more easily and more firmly than
the other : and that the chyle in the thoracic duct, above the entrance of the splenic
absorbents, and after being mixed with the reddish coagulable lymph, appears the red*
dest, and coagulates very rapidly. The gradual change of the chyle into blood, they
argue, seems, therefore, to be a consequence of its passage through the mesenteric
glands, and of the admixture of the reddish coagulable lymph supplied by the absor-
bents of the spleen.

«« The properties of the spleen in the foetus, and in old age, support this view, In
tfce foetus the spleen is known to be very small, and no chyle is formed in the intesti-
nal canal in this stage of existence ; the spleen, accordingly, intended to assimilate the
alimentary matter derived from the intestinal canal, is of no importance. After birth,
when the* formation of the chyle begins, this organ shows itself full of blood, and in-
creases in size rapidly. In old" persons, the spleen is commonly diminished : it appeal's,
therefore, like the lymphatic glands, to decrease in size with age."

In order to establish the second circumstance which supports their third conclusion,
professors Tiedemann and Gmelin had recourse to direct experiment, which fully prov*
ed its accuracy. They conclude by observing, that pathology furnishes many confirma-
tions of their opinion ; and they adduce the instances of scrofula, diseases of the chy^
iopoietic viscera in general, intermittent fever, and abdominal dropsy* ,

Of the Mucous Coat of the Digestive Canal, and the Functions of the aancttt

and large Intestines*

Note Oo

The mucoua membrane of tfie Digestive Tube has an amphorous and spongy structure,
more or less soft, and of 'variable thickness. The free surface of this membrane pre-
sents,— 1st. Valyules formed of folds of this membrane, of the submucous tissue, and
of muscular fiures contained within these folds ; 2d, more or less evident depres-
siqns, which are generally infundibuliform, cellular, or alveolar ; the follicles differ but
little from the alveolar depressions ; they have a narrow neck, more or less lengthened,
and a dilated body lodged in the submucous tissue. They are formed of this membrane
turned back upon itself, and exteriorly surrounded by dense cellular tissue Supplied
with numerous capillaries. They vary greatly in number in different situations ; 3d,
small eminences called papillae, and villosities which are situated on the unattached sur-
face of the membrane. These assume various forms, but in general, those in the pylo-
ric extremity of the stomach and in the duodenum, being more broad than long, present
a laminated appearance ; those of the jejunum are long and straight, and are correctly
called villosities, whilst towards the end of the ileum, and the colon, they reassume the,

* The nerves of the spleen are chiefly from the cceliac plexus, and form a reticulum.
around the splenic artery, accompanying this vessel in all its distributions ; a very few
minute nerves also come from the par vagum and inosculate with those of the cceliac
plexus.

M. Defermon recently- found, in his experiments on the abdominal circulation, that
the spleen is susceptible of contraction under the influence of various substances which
act directly on the nervous system, such as strychnine, camphor, acetate of morphine,
&c. In dogs to which he had giren strychnine, the spleen, which is usually flat, rolled
itself into a spiral form when absorption commenced, and presented very energetic
contractions. The action of camphor was different : the spleen under its influence
became rugous, and its surface assumed a granulated appearance, producing a degree
of motion in the whole organ.

The influence of these agents on a viscus, whose nerves are nearly exclusively be-
longing to the ganglial system, confirms our views respecting the extent of function,
v;hich we have attributed to this system.

E

34 APPENDIX.

laminated character. The Villosities, are semi-diaphanous, their surface is smooth, with-
out any appearance of a cellular or vascular texture, both of which have been impu-
ted to them. Professor Meckel, whilst he doubts whether or not they possess either the
one species of structure or the other, is inclined to believe, from analogy with certain
parts of some vegetables, that they consist of a continuous series of cells.

The villosites of the mucous membrane of the intestinal canal appear to be a mode of
Structure which, as well as that of folds, gives an increase of the extent of surface exposed
to the influence of external agents. " Villosities are only more minute forms of membran-
ous folds, differing somewhat from the latter in the greater proportion of the extent of
their surface to that of their base, and thus presenting where they exist, — which is
chiefly in the small intestines, — the means by which the above-mentioned purpose may
be most perfectly fulfilled."

The epidermis, or epithelium, is very manifest, at the openings into the digestive ca-
nal, but soon becomes much less so, as we advance into the cavities, until it becomes
entirely indemonstrable. The blood vessels and absorbents of this membrane are abun-
dant. Its nerves are chiefly of the ganglial system, but at its natural openings they come
also from the cerebro-spinal system.

The functions of the mucous membrane of the digestive tube may be enumerated un-
der the following heads.

1. Absorption, of which the Villosities are the most active agents, although not the
only agents.

2. Secretion, which is perspiratory and follicular ; and of which the products differ-
ing much according to the situation whence they issue, are generally known under the
term mucosity.

3. Tonic contraction, which is promoted by the action of the muscular fibres.

4. Sensibility, varying in all its grades, and modes of manifestations.

The mucous membrane of the intestinal canal is next to the first, if not the first of the
structures of the body which comes into existence. Its characters are but little modi-
fied by age or sex. (See the Note in the Jlppendix, on the Devclopement of the Textures
of the Foetus.)

Of the Digestive process in the Intestines. — It. is not necessary to say much in addition
to what is contained in the text. This process, as it respects the whole apparatus des-
tined for its performance, may be divided into three stages, — namely, Chymifaction,
Chylifaction, and Fecation : the first is performed in the stomach, the second in the
small intestines, and the third in the large intestines The first has already come be-
fore us, and the second was noticed, when the functions of the liver were under consi-
deration. We may, however, remark, respecting chylifaction, that it is by no means a
chemical process, for there subsists no chemical relation between the chyme and the
biliary and pancreatic juices, which are the materials of the ne\v product ; this process
Is altogether a vital one, and the result is very nearly alike under every circumstance.
Chylifaction chiefly takes place in the duodenum and jejunum from the admixture of the
juices just now mentioned with the chyme. The experiments of Professor Mondini
confirm the inference, that the duodenum is distended with the chyme when the bile is
•passing into it.

The absorption of the chyle commences about the end of the duodenum, and goes on
throughout the jejunum, and the first half of the ilium, and is completed at the termi-
nation of this intestine ; this function takes place with greatest activity in the je-
junum.

To the function of the larger intestines may be given the term Fecation ; because it
is in this situation of the digestive canal that the foccal matter is formed. In its course
through the small intestines the alimentary matters are deprived of their chyle, and of
a portion of their more aqueous parts : the residue is poured into the colon, where its
course is more slow and where it assumes new characters. The fecal mass, according to
the properties which it presents a"t the commencement of the colon is evidently composed
*— 1st, of the residue of the aliments ; and 2d, of the excrementitial parts of the secre-
tions poured into the superior part of the digestive tube. The fasces, when they arrive
in the rectum, or at the time of their expulsion from the body, are greatly increased by
the more solid parts of the secretions poured out upon the internal surface of the co-
lon, their more fluid parts having been absorbed. It is, in some measure, owing to the
quantity and properties of the excrementitial parts of these latter secretions, which prin-
cipally proceed from the follicular apparatus of this intestine, that the fseces present
distinctive characters.

Gaseous substances generally are found in greater or less abundance in the small in-
testines. This gas may come from more than one source : it may arise from the
change which the elementary substances undergo in their course ; or it may be secre-

OF TUB FUNCTIONS OF THE KIDNIES ££

ted by the mucous membrane of the intestines themselves. While we would not al-
together deny a snare in its production to the former, we contend for the latter. We
believe that the mucous membrane of the digestive canal may both secrete gaseous sub-
stances and absorb them ; and we found our belief upon the following circumstances: —
1st, We have proofs derived from experiment and observation that gaseous substances
are absorbed and given oft' from the mucous membrane of the respiratory apparatus.
2d, Pathological facts intimately connected with the functions and properties of this
membrane in different parts of the body, support the position. We have, however, no
doubt that the changes ^hich the alimentary substances undergo in the stomach occasi-
onally gives rise to gaseous products; and we believe that a similar result follows the
remoVa of the excrernentitial matters in the colon and rectum. As to the chemical cha-
racters of the gaseous substances found in different parts of the intestinal tube, see
Chapter II,

Of the Functions of the Kidneys,

Note P.

The latest, and, we think, the most correct examination of the intimate structure of
the kidnies was given in the text. We now add the ktest experiments which have been
made, in order to ascertain the extent of their functions. Messrs. Dumas and Prevost, of
Geneva, and afterwards Mr. Segales, of Paris, found on examining the blood of living
animals, whose kidnies had been extirpated, that it contained urea*, the quantity of
which was increased in proportion to the duration of life after the operation ; whilst
this substance could not be detected in the blood of those animals in which the urinary
secretion was uninterrupted. The last mentioned physiologist, moreover, having in-
jected an aqueous solution of urea into the veins of an animal, observed the secretion of
urine rapidly increased by it, this substance so quickly eliminated in the process that,
after twenty -four hours, it could not be detected in the blood. It seems, therefore,
not improbable that the debris of the textures, being carried into the circulation, is con-
verted by the influence of the organs and vessels through which it flows into the sub-
stance called urea, and that the function of the kidnies is to eliminate it, with other
materials which would be hurtful to the system. These experiments, show that the urea
is not formed in the kidnies by their appropriate functions, as was believed by some phy-
siologist, but that it, and, probably other materials which are removed from the blood
by these organs, are deriverd from other sources.

The following facts more closely relate to pathology, than to physiology.

In inflammatory fever the urine is red or deep coloured, or even a deep brown, and
perfectly transparent until the disease tends to a termimation ; it then deposits the la-
terititious sediment, which is of a reddish colour, and consists of animal matter, phos-
phate of lime, lithic acid, and sometimes lithate of ammonia, According to i)r. Prout
lithateof soda, and phosphates of ammonia and soda, are also present. In intermittents
the appearance of the urine varies according to the stage of the desease ; but when a
paroxysm of ague is over, what is then voided deposits a peculiarly red powder, which
has been examined by Dr. Prout, and found to be a distinct acid, which he named ros-
acic acid, from its colour. In typhus fevers, the urine is loaded with gelatin and urea.
It deposits in gouty disorders, as it cools, a large quantity of lithic acid, in the form of
red crystals. The urine in hysteria is of a very pale colour ; it contains abundance of
saline ingredients, but is very deficient in urea and animal matter. In jaundice it is
usually of a brown colour, arising from an admixture of bile. In various other disor-
ders, especially those affecting the secreting function of the liver, more particularly
\rhen that function is imperfectly performed, the urine very generally presents a brown
and muddy appearance, owing to the kidnies having assumed an action in some degree
vicarious of that of the liver, and thus removed much of the carbonaceous and effete
materials from the blood usually eliminated by that viscus. A similar appearance of the
tirine is often met with in those fevers wherein the functions of the liver are much em-
barrassed, especially in those fevers called bilious, and in those which are met with in
warm climates- In ascites this fluid frequently assumes a yellowish green colour, and
is extremely viscid. It deposits a copious sediment of rosacic acid mixed with lithic
acid, phosphate of lime, and animal matter ; and is often loaded with albumen to such

* Five PI. in res of blood contain one scruple cf urea,

36 APPENDIX

a degree, as to deposit it wheii heated, or on the addition of concentrated sulphuric acid.
Those appearances, however, are not constant, they are more generally met with in the
acute forms of dropsy. In some cases of rickets, the urine has been found saturated
to a high degree with phosphate of lime. Its character in diabetes is well known.
Blood is frequently found in the urine ; it gives this secretion more or less of a dark
colour and muddy sediment. Mucus is also met with in this fluid, during diseases
affecting either the kulnies, the raucous membrane of the bladder, or the prostate
gland.

Of Absorption.
Note Q.

L Of Absorption fram the Digestl-oe Canal It appears, from the experiments of Tie*
demann and Gmelin on absorption, that the lacteals take up the digested and dissolved
portions of alimentary substances, and convey them as a chyle through the thoracic
duct to the blood-vessels : but as odoriferous, colouring, and some saline substances,
are not absorbed by them, and yet are found in the blood of the vena portse, and in se-
creted fluids, it must necessarily follow, that there must be some other way than the
thoracic duct, by which they pass into the blood.

The following- are the chief suppositions which have been offered in explanation of
the facts: — " Either all the lacteals do not enter the thoracic duct, and part of them
join the veins which form the vena portae, and thus transmit their contents into the
blood of the vena portae ; or substances pass directly from the stomach and intestinal
canal into the veins ; or finally, both of these suppositions may be true."

These physiologists found, that quicksilver injected into the absorbents of the intes»
tinal canal easily reached the mensenteric veins and the vena portse, and this communi-
cation was found to take place in the mesentedc glands. By means of this communica-
tion they explain the appearance of streaks of a substance like chyle, which is perceiv-
ed in the blood of the vena portae after taking food — a fact which has been frequently
observed by other anatomists.

Though the passage of chyle into the vena portae, may be explained by this connec-
tion of the absorbents with the veins of the intestines, it 'would appear from the experi-
ments, that the passage of odorous colouring and saline substances, does not take place
in the same way. The presence of alcohol, gamboge, indigo, could never be detected
in the lacteals, or thoracic duct, though it was abundantly manifest in the blood of the
mesenteric veins, and in the vena portae. They therefore conclude, that the passage of
these substances must be effected through other channels, and that these channels must
be the radicles of the veins of the intestines. It was found, on examining blood taken
from a branch of the mesenteric vein of a dog, to which sulphuro-prussiate of potass
had been given, that no streaks of chyle were present, but the saline matter was per-
ceived. From this, and other experiments, they conclude that the veins of the intes-
tines appear particularly to absorb heterogeneous substances, such as those already par-
ticularized, whilst the lacteals take up nutritious matter ; and consequently, that sub-
stances taken into the digestive canal may pass into the mass of blood — 1°, through the
absorbents, and the thoracic duct; 2°, through absorbents, which are united with veins
in the mesemeric gland; 3°, through the radicles Or the commencement of the mesen-
teric veins which ultimately form the vena port*.

, And it seems established by the experiments, that the vena portae receives chyle
from the absorbents, and other substances which are taken up from the intestinal
canal by the veins themselves, and as the blood of the vena portse, into which these
materials are conveyed, passes through the liver, this viscus must be regarded as an
organ of assimilation as well as of secretion. See the Note 01* the Functions of the
Liver. App. p. 25.

II. Of Absorption in the Lung's. — Professor Mayer, of Bonne, infers, from experi-
ments instituted in order to ascertain to what extent absorption takes place from the
lungs —

1°. That animals support a considerable quantity of liquid injected into the lung's,
\vithout experiencing mortal symptoms from them ; but these injections should DC
performed by an opening made in the trachea.

2°. The symptoms of suffocation which arise from injections are not serious when
\ve inject pv.re water ; but they become so when thick fluids, for example, oil which
obstructs the aerial passages, or some chemical eolations, which inflame tho bronchial
surfaces, ftre employed in this manner.

OP ABSORPTION. 37

3°. The fluid* and solutions injected into the lungs are absorbed more or less quick-
ly, according to their nature, and their degree of concentration.

4U» This absorption is in general very great, but is less in young and newly born
animals than in adults.

5°. Absorption takes place by the pulmonary veins, for it has occurred in the space
of three minutes ; the fluids injected are found in the blood before they are perceived
in the chyle ; they are found in the chyle : they are found in the left auricle. Lastly,
absorptio'n is carried on even although the thoracic duct be tied.

6°. Absorption is likewise performed by the lymphatic vessels, but more slowly.

7Q. The veins of the -stomach and intestines also absorb, but in much smaller quan-
tities.

8°. The existence of fluids absorbed by the veins can be demonstrated in the blood.
It is easy to discover there the prussiate of potass, the muriate of iron, arsenic, &c.
The prussiate of potass injected into the lungs can be traced, first in the arterial blood
of the heart and arteries, then, if the injection be continued, in the venous blood.

9Q. These substances can be discovered in abundance in the urine in the bladder,
and in that in the kidneys. The prussiate of potass can be discovered in it seven mi-
nutes after the injection.

10°, The prussiate of potass is likewise deposited, and even in considerable quan-
tity, in the serum of the pericardium, of the pleura, of the peritonaeum, in the synovia,
under the skin, and in the milk.

liy, When the prussiate of potass is injected, it can be discovered after some hours,
not only in the fluids, but also in many of the solids : several of these, parts then be-
come green or blue with the muriate of iron, viz. the cellular tissue uHder the skin,
and in the whole body, the fat, the serous and fibrous membranes, the aponerouses of
the muscles, tendons, the dura mater, periosteum, &c.

12°. The membranes of the arteries and veins 5 even the valves of the heart can be
thus entirely coloured blue by the same agent.

15°. The parenchyma of the liver and spleen cannot be coloured blue, but some-
times the cellular tissue around their great vessels. The lungs, the heart, and the kid-
neys, can be coloured blue.

15°. The substance of the bones and their marrow, the substance of the muscles
and that of the brain, spinal marrow, and nerves, evince no change of colour with
the muriate of iron. The nerves of the brain and spinal marrow seem to exert a re-
pulsive and exclusive force, on the contact of fluids foreign to their nutrition. It may
be concluded from this that the opinions of many physiologists, that poisons act mor-
tally, when they are applied to these parts of the nervous system, are not well founded,
and are devoid of direct proofs.

16°. These experiments may also throw some light on secretion, the reproduction
and nourishment of bodies ; they teach, moreover, the passage of liquids from the mo-
ther to the foetus. When the prussiate of potass has been administered to the mother,
it can be detected in the water of the amnion, in that of the chorion, and of the um-
bilical vesicle, in the liquid of the stomach, in many solid parts of the foetus, for ex-
ample, in the kidneys, in the stomach, &c. as also in the placenta. When a foe-
tus, to the mother of which prussiate of potass has been given, is placed into a mixture
of spirit of wine and muriate of iron, it becomes blue coloured. Thus we acquire a
certain proof of the passage of fluids from the mother to the fcetus, a proof that has
been vainly sought for until now : — the fluids taken into the blood of the mother are
deposited in the tissue of the placenta, and are thence absorbed by the veins of the
foetus*

FIL Of the manner in which Absorption in performed; andef Exhalation. — M. Magen-
die (Journal de Physiol, Experiment. JVo. I.} infers that the chyhferous vessels absorb
chyle only, and that the veins possess the faculty of absorption. He has endeavoured
to disprove the absorbent power of the lymphatic vessels, but in this lie has not suc-
ceeded. He considers also that his experiments justify him in concluding, that, in all
cases where artificial or real plethora exists, and the veins consequently are distended,
no absorption takes place, or only in a slight degree, and after a greater lengt.li of time,
than under ordinary circumstances ; whilst, when the original quantity of blood is di-
minished by venesection, absorption follows in one-fourth of the time in which it is
found to occur when depletion has not been previously had recourse to. He considers
it therefore, to follow, that absorption is influenced by the congestion and caliber of
the blood-vessel;}.

" The further pursuit of these researches led M. Magendie to the conclusion, -that
absorption is nothing more than the well-known phenomena of capillary contraction*
which takes place vhen tubes Of a smell rnlibre are' immersed in fluids: a pheno-

38 APPENDIX;

menon whose energy is in a direct ratio of the affinity of the fluid for the surface of the
tube, — and in an inverse ratio with the diameter of the latter.

" It appears to me then,'* he adds, " beyond doubt that all the blood-vessels, venous
and arterial, whether duad or living, small or great, present, in their parietes, a physical
property calculated to account for the principal phenomena of absorption. To affirm
that this property is alone able to produce all the phenomena of absorption would be to
go beyond what is warranted by a correct logic ; but in the present state of facts on the
subject, I know not any thing which weakens the inference which I have drawn, but-
many which may be adduced in its support."

" By this method of explaining absorption," he observes, ts we solve a number of
other phenomena in the living system otherwise inexplicable : for example, the princi-
ple on which dropsies are cured, the relief from congestion and inflammation produced
by blood-letting, the want of efficacy in medicines during those febrile states of the sys-
tem in which the vascular system is greatly distended: the propriety of that practice
which institutes blood-letting and purging prior to the administration of other active
medicinals, the rationale of both partial and general dropsies, under circumstances of
cardiac or pulmonary diseases ; the use of ligatures upon limbs after the bite of veno-
mous animals, in order to prevent the consequences of such accidents," &c.

That absorption takes place exclusively through the medium of the veins cannot, in
our' opinion, be granted to any part of the body or to any organ, excepting to the brain.
As respects this organ, we believe that sufficient proofs exist of this function being1
performed entirely by this set of vessels. {See t/tc Note on the Structure and Functions
of the Jfiwin.')

This very interesting subject has been further investigated by Messrs. Segales and Fo-
dera. Journ. de PhysioL .April 1822, and Jan. 1823.) The latter physiologist entered
upon a series of experiments, which, although they appear not to us fully to substaniate
the opinion of Magendie that venous absorption takes place by capillary attraction,
seem nevertheless to show that this process, or one similar to it, actually exists to a
certain extent in the living body, and that though it may be subordinate to more ener-
getic influences, it should not be altogether overlooked in our inquiries into the ope-
rations of the animal economy.

Mr. Fodera's end, in his experiments, has been to demonstrate that exhalation, which
he calls transudation : and absorption, which he names imbibition, are similar phenomena,
owing to the capillary attraction of the parietes of the different vessels, owing to their
porosity, operating, in the first case, from the interior of the vessels to the exterior, and
in the second from the exterior to the inferior.

Magendie conceived he had already proved that venous absorption takes place by
imbibition, and came to the conclusions which we have now stated. One of his experi
ments consisted in completely isolating a portion of vein, and placing its- surface in
contact with an active poison : its presence was soon discovered at the internal surface
of the vessel. M. Fodera then inverscd the experiment. He injected a poisonous sub-
stance, with every proper precaution, into the interior of a portion of artery comprised
between two ligatures, and isolated frcm its cellular tissue, its lymphatics, and its vasa
vasomm .- poisoning took place. He obtained the same result by filling with poison a
portion of an artery, vein, or of intestine, removing and placing them either at the sur-
face of a wound made in another animal, or in the abdominal cavity. In these different
experiments, the rapidity ot the poisoning appeared to vary according to the age and
kind of animal ; the thickness and length of the portion of vessel or intestine, its
greater or less distension : the more or less perfect solution of the injected matter, &c.

Mr. Fodera has also seen gases absorbed in the same manner. He placed on the pe-
ritoneal cavity of a rabbit sulphurretted hydrogen, enclosed in a portion of intestine re-
moved from another animal ; and at the end of some time, symptoms of poisoning ma-
nifested themselves, and the sulphurretttd hydrogen was no longer found in the intes-
tine.

If, in a living1 animal, an artery or vein is exposed, an oozing is observed to take place
through its parietes. This oozing augments, if a ligature be applied to the vessel : dif-
i'erent dropsies may likewise be produced by the ligature of the great venous trunks.

Mr. Fodera concludes, from these facts, that exhalation is only a phenomenon of
transudation through the parietes of tjie vessels, as many physicians had thought, be-
fore the exhalent vessels were imagined.

The following experiments prove that, at least, on the dead body, transudation of li-
quids may take place at the same time from the interior to the exterior, and rice versa
through the vascular or intestinal parietea. Fodera filled a portion of a rabbit's in-
testine v.'Uh a solution of prussiate of potass, and plunpred it into a solution of'hydrochlo-

OP ABSORPTION. ^Q

rate of lime : he Introduced into another portion some hydrochloric acid and surround-
ed it with sulphuric acid ; finally, he placed a bladder, filled with tincture of turnsol,
in a solution of gall nuts. Sometime afterwards he found in the interior of these por-
tions of the intestine and of the bladder, hydrochlorate of lime, sulphuric acid, and gal-
lic acid, by the tests of nitrate of silver, hydrochlorate of barytes, and sulphate of iron;
and in the' liquids in which they had been immersed, prussiate of potass, hydrochloric
acid, and tincture of turnsol, by the tests of sulphate of copper, the nitrate of silver, and
by the reddish colour of the solution of galls being rendered bluish by the potas.s.

On injecting at the same time into the pulmonary vein of a sheep, a solution of hy-
drochlorate of barytes, and one of the hydrocyanate of potass into the trachea, Fo-
dera also found hydrocynute of potass in the pulmonary artery, and hydrochlorate of
barytes in the bronchia:.

Similar phenomena may be produced upon a living animal, Fodera has found, for
example, in the bladder or in the thorax, substances which had been injected into the
peritoneum ; and in the abdominal cavity, substances which had been introduced into
the thorax or bladder. In these experiments he employed the solution of gall and sul-
phate of iron, or rather, the latter salt and prussiate of potass.

The black or blue colour, announcing that transudation has taken place, is frequently
not observed until the end of more than an hour : it may be rendered almost instantane-
ous by putting in action the galvanic influence. For this purpose, this ingenious expe-
rimenter injects into the bladder, or into a portion of the intestine of a living rabbit, a
solution of prussiate of potass, communicating with a copper wire ; externally, he places
a cloth wet with a solution of the sulphate, communicating with an iron wire : these
wires are put in contact with those of the pile. If the galvanic stream be directed from
the exterior to the interior,. by making a communication between the iron wire and the
positive pole, and between that of copper and the negative, the tissues of the organs im-
bibe the Prussian blue : if the stream be changed, the colour appears on the cloth.

M. Fodera injected into the left cavity of the thorax of a rabbit a solution of hydrocy-
anate of potass, and into the peritoneum a solution of sulphate of iron ; he afterwards
kept the animal placed on its left side for three quarters of an hour. At the end of this
period the animal was opened, when he found that the whole of the tendinous part of
the diaphragm had imbibed the blue matter; the muscular part was much less tinged,
and only in isolated points. The substernal lymphatic glands were likewise blue.
The thoracic duct contained a bluish liquid : the peritoneal membrane of the stomach,
and duodenum was coloured with spots of the same colour : they were observable, but
in less number, on the rest of the digestive canal and on the arteries. The lymphatic
glands of the mesentery, the suspensory ligament of the liver, the epiploon, were also
tinged blue. Some small subperitoneal veins presented a slight blue colouration of the
liquid contained in their interior. Twelve hours afterwards, the blue tint of these dif-
ferent parts was much more intense.

The progress of the colouration may be traced, and the phenomenon in some measure
be seen in its different phases t by injecting a femiretted solution of prussiate of potass
into a portion of the intestine of a living animal ; tying both ends, and plunging it into
a bath containing sulphate of iron. At first a slight coloration, only, is observable in the
parts, which gradually becomes deeper : afterwards the liquids of the lymphatics and
of the blood-vessels become coloured in turn. In these latter, the coloration begins
by small ramifications, and afterwards extends to the branches, which are observed to
be tilled with intervals of blood and a blue liquid. In these experiments Fodera
discovered the presence of the prussiate of iron in the lymphatic vessels, in the thoracic
duct, and, finally, in the portion of the inferior vena cava contained in the chests.

Mr. Fodera concludes, from these different experiments, 1st, that exhalation and ab-
sorption take place by transudation and imbibition, and depend on the capillarity of the
tissues ; 2dly, that th'is double phenomenon may take place in every part, and that the
liquids imbibed may be conveyed equally well, either by the lymphatic vessels, or by
the arterial or venous. But (the author very wisely adds) the phenomena of exhalation
and absorption ought not to be considered as connected alone with imbibition and tran-
sudation : the modifications which they experience from the action of surrounding-
agents, from the nervous influence, the state of rest and motion, the energy of the cir-
culation, the affinities of the substances with the tissues, the derangements produced by
disease, and the elaboration which the fluids undergo whilst absorption and exhalation
are taking place, ought likewise to be studied.

Mr. Fodera endeavours to explain the increase of exhalation in the phlegmasiae by
the dilatation which the parietes of the capillary vessels experience ; the interstices of
the fibres which form these parietes become at such times increased, and, consquently,
permit a more ready issue to the fluids : the serosity and the white globules, which are

40 APPENDIX,

smaller than the red, are first effused ; at lost the red globules themselves occasionally
escape. It will be seen that this mode of conceiving- the phenomenon does not explain
the infinite modifications which the liquids exhaled into the inflamed parts undergo.

Mr. Fodera notices cases in which the lymphatics or thoracic duct have been said to
contain different substances, which had been introduced either into the digestive ca-
nal, the serous cavities, or into the cellular tissue. If the effects of absorption are not
manifested, in the experiments, where a portion of intestine, containing poison, has no
longer any communication with the rest of the body, except by a lymphatic vessel, we
must seek for a cause in the extreme slowness of the circulation of the lymph. M. Fo-
dera inserted some liquid prussiate of potass in the subcutaneous cellular tissue of the
thigh and abdomen of two young rabbits. In the first animal, at the expiration of a few
minutes, and in the second, at the end of half an hour, he found it in the lymph of the
thoracic duct, in the urine, the mucous of the intestines, the synovia, the s'ermn of the
blood, the serosity of the pericardium, of the pleura, and of the peritoneum, as well as
in all the solid parts, except in the crystalline lens, the cerebral substance, the interior
of the nerves, and the ossous tissue. In another experiment the interior of the nerves
presented traces of it.

Would not these experiments tend to prove that absorption in these cases had ta»
ken place at tbe same time, both by the lympatica and blood-vessels ?

While the German physiologists have ascribed absorption to the absorbents and veins
only, Messrs. Magendie and Fodera have extended this function to the arteries also. In
this, however, we think that they have been misled by fallacies which had crept into
then- experiments, and especially by the unnatural position and deranged actions which
the operations and agents required by the experiments induce in the animal and in the
parts experimented on. From every consideration we are led lo infer, that the infer-
ences at which Tiedemann, Gmelin, and Mayer have arrived, approach the nearest to
truth.

The experiments performed by Darwin, and more recently by Wollaston, Brande,
and Marcet, tend to prove that different substances introduced into the stomach are
found mixed with the urine, without having passed by the lymphatic or blood-vessels.

Fodera has repeated these experiments, and made them undergo an ingenious
modification, which has discovered to him phenomena unobserved by former physiolo-
gists. He introduced into the bladder a plugged catheter, after having tied the penis in
order to prevent the urine from flowing along the sides of the sound. He laid bare the
oesophagus at the anterior part of the neck, and injected into the stomach a solution
containing some grains of the ferruretted hydrocyanate of potass. This being done,
he frequently removed the plug, and received on filtering paper the urine which es-
caped. On this paper he dropped a solution of sulphate of iron, and added to it a little
hydrochloric acid in order to destroy the color. In one experiment the prussiate was
detected in the urine ten minutes after its injection into the stomach, and in another
live minutes afterwards. The animals were opened immediately. The salt was found
5n the serum of the blood taken from thethorac portion of the vena eava inferior, in the
right and left cavities of the heart, in the aorta, the thoracic duct, the mesenteric
glands, the kidnies, the joints, and the mucous membrane of the bronchia:.

This important experiment proves the extreme rapidity of absorption ; it shows also
that the prussiate of potass found in the urine, is conveyed thither by the ordinary cir-
culating ways.

The following experiment demonstrates the rapidity of pulmonary absorption in par-
ticular. Fodera opened the thorax of a rabbit, and removed the heart, immediate-
ly after some prussiate of potass had been injected into the trachea. This operation was
performed in twenty seconds : the interior of the left auricle, however, presented a
bluish green colour, which was more deep at the mitral valve and les» apparent in the
aorta. The absorption, therefore, seems to take place at the very instant when the in-
jection has penetrated into the subdivisions of the bronchia.

We are of opinion, that to limit the process of absorption in every part of the body,
and under every combination of circumstances to which it is subject, to one particular
process, or to one particular conformation or property which the vessels, whether blood-
vessels, or others, may possess, would in the present state of our knowledge, be to
draw an inference not' justified by many important facts. On the contrary, it seems more
probable that not only the vital properties, but those of a physical nature, are requisite
to the production of "the phenomena in question; and that the Jatter set of properties
are under the control of the former.

Instead of attempting to show that those physical properties for which Messrs. Magen-
die and Fodera have contended, are not to a certain degree efficient in the production of
the process in question, \ve would only argue for their subordinate character, which may

OF ABSORPTION.

41

be in support of his purely physical properties ; but, although the vital properties arc
chiefly predominant in the operation, yet those for which they contend may have still
a place to a certain extent, which extent is modifiexl by a superior influence.

Investigations into the process of absorption have also been entered upon in America.
Doctors Lawrance, Coates, and others, made thirty-four experiments in which the prus-
siate of potass was introduced into the alimentary canal : from these it appears that ar-
ticles taken into the stomach may be conveyed into the circulation by three channels ;
namely, the vena portae, the oesophageal veins and the thoracic duct, and if all these
are closed, the absorbed matters are no longer conveyed to the circulation or to the^
urine. With regard to the quantity conveyed b\ each, they had no accurate means of
judging. As the quantity of fluid, however, contained in the vena portarum, is so much
greater than in the thoracic duct, it follows, that to produce a colour of equal in-
tensity, a much larger amount of the colouring matter is requisite, and, as the serum ot
the blood of the vena port® gave an equally deep colour, the greater proportion of the
materials must have been absorbed through the veins contributing to this system of
vessels.

In consequence of reading the experiments of professor Mayer of Gottingen, upon
absorption in the lungs, Doctors Lawrance and Coates made a few with that reference.

The animals generally died in about a minute after the injection, from suffocation,
by the ligatures which they placed on the tracheas of most of them. These experiments,
\ve think, go to favour the ideathat absorption from the mucous membrane of the lungs,
is performed principally by the pulmonary veins. They lay particular stress upon ex-
periments 5th and 6th. In the first, the blood from the left side of the heart indicated
the agent in much larger proportion than that from the right side, both being examined
about the same time : viz. seven minutes. In the second, where the examination was
made in a much shorter period, viz. three minutes and a half, and four minutes and a
half, the article was distinctly found in the left side of the heart before it had arrived
in any other part of the system.

The effect of infiltration was also remarkable in these experiments.

The results of five trials of the prussiate in the cavity of the abdomen are here arranged
for inspection.

Animals.

Quantity.

Thoracic Duct.

Carotid and
Jugular.

Urine.

Kitten.

^oz. solu-
tion.

12 & 13 m.
distinct blue.

6 m. distinct
blue.

19 m. no blae.

Idem.

Idem.

4 m. blue.

2 m. no
blue.

10 or 15 m. no
blue. 29 m. distinct
blue.

Idem.

Idem,
nearly.

3| m. blue.

2 m. no
blue.

5 m. blue, not
strongly.

Idem.

ioz.

3 m. blue.

4 m. strongly
blue.

More than 4 m.
doubtful.

Cat.

Uncertain.

9£ m. blue.

5 m. no blue.

More than 9^ m.
no blue,

The short time in which the prussiate reached the upper part of the thoracic duct in
the above cases, induced them to make four other trials in order to ascertain the earli-
est period at which that took place. Half an ounce of solution was employed in each
case.

In the first animal, a kitten, the salt first arrived at the spot of observation in four
minutes, and the quantity gradually increased till seven or eight minutes. In the
second kitten, it appeared in two minutes, The serum of this animal gave a blue
tinge. In the third kitten, in three minutes and a half. Serum of blood also blue. In
the cat, it first appeared in thirteen minutes.

In these cases, the thoracic duct was cut off near its insertion ; and the test applied

F

42 APPENDIX.

there. In consequence of this interruption, previously to the prussiate arriving at the
upper extremity of the duct, the discovery of the salt in the serum of the blood clearly
evinces that it was conveyed there by other channels.

It is mentioned by Magendie, that he has seen, on pressing the lacteal branches so
as to discharge their contents in the direction of the trunks, that those branches would
again fill themselves after the animal's death. They have also witnessed these appear-
ances ; but they do not know of any similar observations to the following made on the
lymphatics, or of any evidence of the actual chemical presence of an article conveyed
after death into either of these systems from without.

Four kittens were bled to what is commonly considered death. The blood ceased
to flow from the divided carotid, and voluntary motion was extinct. Prussiate of potass
in solution was then thrown into the abdomen. It appeared at the thoracic duct in five
and a half, five, fourteen, and twelve minutes respectively. In the two last, the great
vessels originating at the heart were secured by a common ligature. The blue colour
was in every instance perfectly distinct.

In reasoning on the subject of absorption, the question has frequently arisen, whe-
ther the articles found in the living fluids exist there as chemical substances, or have
their chemical nature altered and animalized by the action of the vessels through which
they have entered the system. It was, however, deemed a curious subject of inquiry,
whether artificial chemical changes can take place in the fluids while they continue to
circulate in living vessels, and the ordinary actions of life go on. With a view of as-
certaining this point, they commenced by throwing prussiate of potass into the abdo-
men, and green sulphate of iron into the cellular tissue, in order to try whether the
well known result of their admixture, the prussian blue, would be produced in the ves-
sels. This, however, did not take place : and they resolved to repeat it by throwing
the sulphate, as the article of more difficult absorption, into the abdomen, where this
process went on with more facility, and the prussiate into the cellular substance. On
performing this, they were gratified by the striking result of a distinct and beautiful blue
in the thoracic trunk, and its contents, and in nearly the whole substance and surface
of the lungs. These viscera were preserved in spirits, and are now in their possession.
The blood threw up a coagulum of a strong blue colour, and the lymph and chyle from
the thoracic duct, threw down a blue deposit. Thus not only a foreign, but a pulveru-
lent substance could present its unnatural stimulus and circulate through the vessels,
and accumulate in the lungs, without preventing the actions of life from considerable
exertion, and without occasioning coagulation of the blood. The animal manifested some
difficulty of respiration before she was killed, but walked about without the least diffi-
culty, and uttered no cries, nor other signs of disturbance of its powers. In another
case, the urine and lungs were noted as exhibiting a blue colour. The other parts si-
milar to those above enumerated, are not described as being found coloured. In a
third, the fluid in the thoracic duct was blue, but not the other fluids examined, nor the
lungs. Two unsuccessful trials were also made. In another case the thoracic duct was
tied, and the same process repeated. A divided bluish green was here found in the
urine ; but neither the serum of the arterial blood, nor the lymph of the ductus tho~
racicus, manifested the blue or green.

Of tlte Mion of the Heart and Arteries.
NoteR.

I. Of the Heart. — The muscular fibres of the heart are more apparent in the foetus
than in the adult ; it only participates in the general paleness of muscular textures at
that epoch, although it is deeper coloured than they are. It also is entirely without fat at
this period. In old age the texture of the heart becomes softer and more flaccid than
in the young subject, and its parietes thinner : its cavities enlarge, especially the right,
and its surface is more charged with fat.

The nerves of the heart have been a subject of interest with physiologists. Since
they were investigated by Scarpa opinions have been tolerably uniform respecting them;
and numerous observers have proved the general accuracy of his researches. The
cardiac nerves are chiefly derrived from the ganglia of the great sympathetic : a few
also come from the pneumo-gastric ; but these seem rather to inosculate with the for-
mer, than to go directly to the texture of the organ. The cardiac ganglion, situated

OF THE ACTIONS OF THE HEART AND ARTERIES. 43

behind this organ, seems more particularly to preside over its movements, or to rein-
force with additional energy whatever it may receive from other sources, especially
from the centre of the ganglial system and the other ganglia in the neck and chest.
These nerves, according to our own observations, supply the substance of the heart in
two ways : 1st, There are numerous branches which proceed from the different plex-
uses directly to its muscular texture, and which, dipping between the fibres, give
off' minute fibrillae to these fibres next to them in the course of their descent into
the substance of the heart. 2d, A large portion also of the nerves of the heart form
an t nvelope of the coronary arteries. A part of these seem to follow the arteries
throughout their distributions ; but, before the coronary arteries have ramified to a
great extent, a part ot the nerves surrounding them is detached to the adjoining parts,
so that all the nerves which surround these arteries, like a reticulum or sheath,
do not accompany the ramifications of the latter to their ultimate subdivisions and ter-
minations in the veins, a portion of them appearing to be detached in numerous and
minute fibrillse to the immediately adjoining fibres. Thus it will be perceived that the
muscular texture of the heart receives directly and mediately a very considerable por-
tion of ganglial nerves ; whilst, it may be presumed, that it also receives an accession in
those fibrils which terminate with the nutritious capillaries in this particular structure

The functions of the heart, it may reasonably be supposed, are chiefly the result of
the influence which this disposition of the ganglial system of nerves bestows on its
structure. In addition to the support which this inference derives from the conforma-
tion of the viscus and its relation with the rest of this particular system of nerves, both
n. man and the lower animals, experiments which have been performed by different
physiologists, prove its accuracy* ; and prove it the more conclusively, inasmuch as
they were performed with a view of establishing a different proposition.

But, although the heart derives its chief influence from the ganglial system, it is
ucted on through the medium of the nerves which communicate between this system
and the cerebro-spinal, and which seem to convey an additional influence from the lat-
ter, to the ganglia and plexuses which immediately supply the heart. And as this
communication is more* intimate in the more perfect animals, and the functions of the
cerebro-spinal system are more energetic in them, so it appears to follow that the heart's
action is more" readily influenced either by the increase or diminution of these func-
tions in them, than in the lowest order of animals.

Another point to which it is necessary to advert, is the question as to the active dila-
tion of the heart— a function of this viscus much insisted on by Hamberger, and more
recently by Carson and others. We doubt not that it actually exists to some extent,
in all animals provided with a perfect heart, but we do not believe that it takes place
with great energy. If the dilation, however, of the heart, were a mere result of a re-
laxation of its fibres, its cavities could not be so quickly and perfectly filled by the
mechanical pressure of the blood directed towards them, as we observe that they are ;
and dilation would be only the consequence of this pressure, and be proportionate
to it. But this is not the case ; for, as far as we could judge from observing the cir-
culation in fishes, the dilation seems to precede the flow of blood, the latter appearing*
as a consequence of the former.

Allowing, therefore, that the dilation of the cavities of the heart takes place to a
certain extent — an extent which it is difficult fully to determine, but which we consi-
der much less than that contended for by Hamberger and Carson, one of the causes ct"
the flow of blood in the large veins will be apparent.

The heart is perfectly insensible in its natural state. This was satisfactorily shown in
an operation performed by ML Richerand, in 1813, wherein he divided the ribs and re-

* Willis divided the eight pair of nerves in the neck with a view of paralysing the
action of the heart, but death did not supervene until some hours, and in some casee,
not until several days, after the operation. In the experiments of Legallois and Dr.
Phillips, destruction of the brain and spinal marrow did not necessarily and immediately
put a stop to the action of this viscus : although, as should be expected, it was greatly
influenced by the privation of a necessary and an accustomed influence. In experi-
ments which were performed on several species of fishes, the actions of the heart con-
tinued long after the destruction of the cerebro-spinal masses, and frequently for u
short time after it was removed from the body. Lastly, foetuses have been born, in
which the action of the heart and circulation were perfect, although tiiey wanted both
brain and spinal cord : and many of the lower classes of animals have continued to !;' ,.
for a very considerable time after decapitation,

44 APPENDIX,

moved a portion of scirrhous pleura, thus allowing the pericardium to be expo&ecL-
The patient was perfectly insensible of any impression, when M. Iticherand touched
this organ, although the pericardium, the part through which it was handled, is evi-
dently the must sensible part of it during disease : in a'state of disease its organic sen-
sibly becomes indistinctly and obscurely developed.

TI. Of the Arteries. — The arteries throughout the body are smTOunded by the gan-
glial nerves. These nerves form a reticulum around them, from which reticulum very
minute fibrillse are given off and dip into their fibrous or muscular tunic.

This particular disposition of the ganglial nerves on the arteries ought to be kept in
recollection when we inquire into the functions of the latter. How far it tends, not
only to the discharge of the more manifest actions which the arterial system performs,
bvit also to those insensible changes which the blood undergoes in health and in dis-
ease, and to the assimilation of the chyle and other absorbed materials conveyed into
this fluid, we have ventured to state at another place. We shall here merely take no-
tice of an opinion relative to the operations of this class of vessels in the circulation of
the blood, lately contended for by M. Magendie. This physiologist has inferred from
his researches on the circulation, —

*< 1. That neither the larger nor the smaller arteries present any trace of irritability.

« 2. That they are dilated during the heart's systole.

"3. That they are capable of contracting themselves with sufficient force on the
blood they contain, so as to propel it into the veins.

" 4. That the blood in the arteries is not alternately at rest and in motion ; but that
it is, on the contrary, in a continued succedaneous (by little jets) motion in the trunks
and ramifications — and uniform in the smallest ramifications and divisions.

« 5. That the contraction of the left ventricle of the heart, and the elasticity of the
larger and smaller arteries, furnishes a satisfactory mechanical reason for these pheno-
mena,

" 6. That the contraction of the heart and arteries has a considerable influence on the
coxirse of the blood through the veins."

We cannot concur in these conclusions, especially in the sweeping inference which
forms M. Magendie's fifth proposition : and we might, were it consistent with our limits,
point out various fallacies in his experiments, to some of which, indeed, all experiments
on living subjects are more or less liable, viz. the unnatural position of the animal dur-
ing their performance, and more particularly as respects the operations of the part im-
mediately its subject. If M. Magendie limits the process to the mechanical means in-
dicated above, we would ask, how he accounts for the influence of mental emotions in
determining the action of the vessels in particular parts of the body ? How the diversi-
fied influences of numerous external agents on the circulation can be explained ?
Wherefore so very opposite effects are produced upon the arteries, when one extremity
is placed in a pail of ice, and another in a pail of warm water ? How can he reconcile
his conclusions with the very satisfactory experiments performed by Sir Everard Home,
Dr. Hastings, and others ? and how he can account for the determinations of blood to
particular parts, whilst a diminishing quantity is sent to other situations ? — if he discard
lite predominating or vital power which the vessels themselves, and especially their
smaller ramifications possess in virtue of the particular structure already noticed. We
readily grant that the larger branches of arteries evince little or lio contractile action,
particularly in their natural state ; but we contend that it increases as we advance to-
\yards the extreme capillaries, the action of which derives the blood to them in larger
proportion, and thus increases both the mechanical and vital properties of the larger
branches supplying them.

We allow that the properties for which M. Magendie contends have an actual place
in the process of arterial circulation ; but they are not the only ones ; they are insufficient
of themselves to accomplish the purposes which he assigns to them ; and, moreover,
they are secondary to, and controlled by, a superior influence.

From these observations it may be perceived that the arteries act in the process of
the circulation, not by means of a contractile action similar to what is performed by the
heart ; nor yet by means of elasticity only ,- but by an organic or vital operation, which is
•nearly imperceptible in the larger arterial branches, but which increases as we advance
to the extreme capillaries ; whilst, on the contrary, the elastic or mechanical properties
augment as we proceed in the opposite direction.

OF THE FUNCTIONS OF THE CAPILLARIES. 45

Of the, Functions of the Capillaries,
Note S.

This class of vessels may be divided into two orders, performing distinct functions ; —
1st, those capillary vessels between the terminations of the aortic arteries and the
commencement of the veins of the body ; and 2d, those between the termination of the
pulmonary arteries and veins of the same name The first of these orders is disposed,
in different proportions, to the compound solids of the body ; the second is distributed
on the surface of the air-cells of the lungs only. In the one are performed changes
which, render the blood unfit for the purposes of the animal economy ; in the other takes
place an elaborate process of an opposite nature. In the first are produced those or-
ganic functions which relate more directly to the noui'ishment of the frame, as digestion,
secretion, and nutrition ; in the second, those preparatory operations on the blood which
enable the sensible and contractile textures of the body to perform their offices. With-
out the accomplishment of the latter, the former could not be performed : for, as the
former depends upon the vital influence distributed to the capillaries and to their re-
spective organs, as well as upon its state in the sources whence it is derived, so does
this influence itself depend upon the operations which take place in the latter order of
capillaries. The importance, therefore, of these operations in the animal economy must
be manifest, as well as the intimate bond which unites them throughout the frame :
without the performance of the one class of functions, the other could not be dis-
charged.

This part of the circulation — the most interesting, perhaps of any, to the physiologist
and pathologist, without being independent of the heart's action, is the least under its
control ; the functions of the capillary vessels continuing to a certain extent, even after
the heart has ceased to contract: and, asha\e been shown by some experiments per-
formed in this country, in France, and in America, these actions are not limited, even
then, to the mere circulation of the fluid which they contain ; for under this particular
circumstance, they may also perform, for a short time, the functions of absorption, and
secretion.

These phenomena may be readily explained when we consider two circumstances ;—
1st, the source whence the capillaries derive their functions ; and 2d, the kind of death
which the animal experiences, and the order in which the different organs cease to act.
We cannot enter here further into this topic ; we have pointed out the way : those who
are interested in it will be able to pursue it ; those who are not, would profit little from
a lengthened explanation.

Before we leave this subject we may notice an opinion which has been entertained
amongst the most eminent physiologists. This relates to the existence of subordinate
sets of minute and colourless arterial capillaries, each devoted to a particular function ;
namely, one to nutrition, another to secretion, and a third and principal set, to the
transmission of the red blood, which, in consequence of the functions of the former two,
have become possessed of venous properties. The first and second of these sets are
considered to be pellucid in their natural state, and, although they cannot be satisfac-
torily demonstrated, in this state, their existence seems to be rendered probable, if not
proved, by many of the phenomena of disease and by artificial injections.

Dr. Alard has lately contended for the existence of a similar set of colourless vessels
connected in the same manner with the veins ; and that whilst those of the arteries
carry the fluids intended for the nutrition of the textures, for the secretions, and exhala-
tion ; these belonging to the veins perform the functions of absorption. Some of these
latter vessels, whose open mouths are present every where, in the most intimate tex-
tures of the organs, as well as on the surfaces of the great cavities, are supposed by Dr.
Alard to terminate in the parietes of the adjacent veins; whilst others unite and form
the trunks which are generally known by the name of absorbents. The discovery of
Dr. Fohman, of Heidelberk, of a communication of the lymphatics of the intestine with
the mesenteric veins, in some animals, concurs to support the proposition of Dr. Alard.
On this subject Dr. Hutchinson, whose physiological knowledge is of the first order,
has justly observed, — the view of Alard — that supposing the existence of minute pellu-
cid vessels, springing from the parietes of the small arteries; distributed to every part
of the body; conveying different fluids, and producing different effects, according as
their vital properties are modified ; having corresponding vessels, which spring from
the most intimate texture of the organs and surfaces of the great cavities, and umte in

46 APPENDIX.

larger tubes, forming1 in some instances long continuous canals, denominated absorbents,
in others running to be inserted into veins, — is one which is. qualified to explain, more
plausibly than any other the mechanism of the distribution of the fluids for the pur-
poses of the organic functions ; and is, besides, capable of obviating the difficulties
which have been presented by the diversity of the results of the experiments of Hunter,
Magendie, Broclie and others, relative to the mechanism of absorption*. (See the Note
on Jibsorptwn.}

Of the Veins.
Note T.

1. As to the precise way in which the veins commence, opinions have been various.
At the place where the capillaries change from arteries into veins, there appears to be
no reason to suppose the existence of either interspace, or vesicular or spongy struc-
ture. The inflected canal of the artery seems to be continuous with the vein. Whilst,
however, this conformation is allowed by nearly all, some consider, with Mr. Ribes, that
the veins have another commencement in addition to this ; and that a certain proportion
of their roots commence in open mouths or in the pores or areolse of the luminous tis-
sues, and in the substance of the organs. Others also suppose with M. Alard, (See the
preceding nvte,) that some of their roots commence in pellucid lymphatic absorbents.

The structure of the erectile tissues, as the penis, the clitoris, the spleen, &c. seems
to support the opinion of Ribes, (which is also that of Meckel, who farther sup-
poses that one cause of the difference of the appearance and functions of organs may
be ascribed to the extent to which the veins originate in particular manner for which he
contends.

The views of M. Alard derive their chief support from the phenomena connected
with absorption, but, although they appear probable, they cannot be fully demon-
strated.

The veins receive but a small proportion of nerves, and these are chiefly from the
ganglia. The nerves supplying the pulmonary veins come principally from the anterior
pulmonary plexus.

2. '1 '/it functions of the veins are — 1st, to bring back the blood from the capillaries to
the heart : 2d, to remove and assist in the assimilation of fluids, which are absorbed by
the lacteals and absorbents; and 3d, in certain situations, and under certain circumstances
to co-operate in the function of absorption.

Thejirst of the operations is performed by means of the vital action with which the
veins are endowed, assisted by the vis a tergo proceeding from the vital action of the
capillaries, — by the contraction of the surrounding muscles viewed in connexion with
the direction of the valves, with which they are provided, — and by the active dilation
of ttie cavities of the heart which derives the blood from the venous trunks.

The third action of the veins, or absorption, seems to be proved by the researches
already detailed. (See Absorption in the Jlppendix.} The venous radicles, either im-
mediately or mediately, seize the absorbed materials, and convey them into the current
of the circulation. This seems to be a vital or organic action, which is probably assist-
ed, in some parts of the body, and under certain circumstances, by the physical property

* Admitting fully the justness of Dr. Hutchinson's remarks, we must observe that,
the existence of the sets of capillaries here contended for by Dr. Alard, is not proved
demonstratively. Indeed, we possess this species of proof in favour only of one set of
capillaries, — namely, those winch constitute the termination of the arteries and com-
mencement of veins. We know that secretion, nutrition, and absorption, are func-
tions of capillary vessels. This has always been granted from the time of Hippocrates ;
but there have been various instruments allotted to the process, some physiologists in-
sist, with Dr. Alard, upon the existence ol subordinate sets of capillaries allotted to
each function, whilst others contend, with M. Richerand, that they take place through
the medium of lateral pores in those capillaries which communicate directly between
the arteries and veins. These veins will come under consideration in the notes in this
Appendix on Secretion and Nutrition*

OP THE MECHANISM OF THE RESPIRATORY ORGANS. 47

of imbibition OP capillary attraction, which all animal textures evince in a greater or
less degree. It should, however, be recollected, that this property is a very subordinate
one to vitality, is entirely under its control, and takes place very imperfectly when this
influence is in full vigour,

The second function of this class of vessels, is the' admixture of the absorbed mate-
rials, and the assimilation of them The former cr mechanical part of this function is
performed generally throughout the body, al hough it takes place to a greater extent
in some instances than in others, as in those viscera in which the blood circulates more
immediately after it has received the chyle and lymph from the lacteal absorbents and
thoracic duct. Hence it chiefly takes place in the heart itself, and in the liver and lungs.
The latter part of this function is essentially a vital one, and appears to us to result
from the vital influence derived from the nerves with which the blood-vessels are pro-
vided. Supposing this position to be correct, we should expect that the vessels in
which this process takes place would be most abundantly supplied with those nerves,
whence we consider the assimilating influence to proceed. Now this is actually the
case, the blood which is carried into the portal veins contains a larger proportion of ab-
sorbed and imperfectly assimilated materials than the blood in any other organ ; and this
particular order of veins, whose office it is to assimilate them, and to eliminate
the effoete elements from the circulating fluid, is provided with a much
greater number of ganglial nerves than any other part of the venous system ; and, in-
deed, even more than the arteries in some situations. This particular set of veins,
therefore, performs a double function, viz. of assimilation, and of secretion ; in the lat-
ter, however, it may participate with the hepatic artery ; for, as the hepatic vein re-
turns the blood of both the vena portee and the artery, the biliary secretion may, pro-
bably, not take place until the terminating capillaries of both have given rise to the
radicles of the vein.

Assimilation goes on, in the next degree of activity, in the lungs, and more or less
partially in other organs of the body.

Of the Mechanism of the Respiratory Organs.
Note U.

I. Of the Structure of the Lungs. — According to the observations of M. Magendie, the
cellules of the lungs do not appear to be arranged in a methodical manner, nor to have
membranous parietes. With respect to the non-existence of the latter, we think that
he was betrayed into error bv the method of investigation which he adopted.* These
cellules seemed to him to be formed solely by the minutest and last ramifications of the
pulmonary artery ; by the radicles of the veins of the same name, which are a
continuation of the former, and lastly, by the numerous anastamoses of all these ves-
sels. These cellules are separated into many distinct lobules, in each of which the
cellules communicate among themselves ; while between the lobules there is no com-
munication.

" The number of cellules is in an inverse ratio to the age of the subject ; consequent-
ly the older the person, the larger is each cellula, or what comes to the same thing,
the fewer are the cellulx.

*' It follows, therefore, that the lungs become specifically lighter as we advance in
fife ; and in support of the correctness of this inference Magendie states that he found,
by actual experiment, that in equal volumes, a portion of the lungs of a man at seventy
was fourteen times specifically lighter than that of a child a few days old."

II. Of the Jlctiom of the Glottis — M. Bourdon, (Recliei*che6 sur le mechanisms de la res-
wrafc'on, &c. Paris, 1820,) considers that the glottis performs the following functions^

in addition to those which are requisite to the formation of the voice.

1. " That is the glottis which suspends respiration during considerable efforts, in op-
posing, by its closure, the escape of the air contained in the lungs.

* He partially filled the lungs by insufflation after their removal from the subject,
and allowed them to dry. When quite dry he found this sort of preparation to be nearly
transparent, and readilv cnt into thin slices ^yith a knife-

4g APPENDIX.

2. " Without the glottis, the action of the abdominal muscles would be constantly em-
ployed in producing respiration : neither compression of the viscera, nor flexure of the
trunk could be produced.

3. " There exists a real co?isensus of action between the glottis and the abdominal
muscles, and through this medium, between the glottis and the different reservoirs, the
bladder, the rectum, the stomach, and the uterus.

4. « « The glottis does not confine its action to the production of the voice ; but by the
aid of the sympathetic connexions which unite it to the abdominal muscles, charged to
concur in, if not to preside over important functions, it excites the greatest influence on
those functions themselves.

5. «« Lastly, in the different efforts there is a tendency to expiration, to the produc-
tion of which the closure of the glottis is an obstacle."

IIT. Of the Effects of Respiration on the Circulation of the Blood.— The experiments
of Haller, Lamure, and Lorry, and subsequently those or Cloquet and Bourdon, have
shown,

1. That, during inspiration, the blood of the vena cava, superior and inferior, is
drawn towards the heart.

2. That, during expiration, the blood is, on the contrary, driven in the same veins,
towards the viscera.

3. That the arterial blood is also driven towards the viscera at the time of expira-
tion.

4. That the alternate motions of the brain is owing to the changes caused by respira-
tion in the flow of blood.

5. That all these charges are but little marked in ordinary respiration ; but that they
come very evident in full respirations, and particularly so during great efforts.

6. Lastly, that, during great efforts the glottis is firmly closed, the air contained hi
the lungs is compressed, as well as all the pectoral and abdominal viscera.

In order to ascertain the precise effects produced by respiration on the venous cir-
culation, Magendie instituted a set of experiments from which he draws the infer-
ences, that respiration modifies the venous circulation;—!0 by the influence which it
exerts on the course of the arterial blood ; — 2° by its direct action on the current of
blood in the veins That in profound respirations and violent efforts, the circulation ap-
pears nearly suspended.

IV. Of the State of the Lungs during Respiration.— The experiments of Dr. Carson
have directed the attention of physiologists to the state of the lungs themselves during
respiration, and under the various influences to which they are usually subjected either
by accident, by operations, or by disease. Dr. Carson had inferred from his experi-
ments, that it is possible to collapse one of the lungs, and to retain it in that state, ad
libitum, by keeping open the communication between the cavity of the chest and the
external air; and further, that upon allowing the opening to close, the lung, in a given
time, will recover its wonted function, thereby rendering it practicable, when conceiv-
ed necessary, to place the opposite lung under the like discipline. In order to examine
the stability of these inferences. Dr. David Williams, of Liverpool, instituted several
experiments, in the presence of Dr. Trail an i otliers, which contradict some of the chief
positions held by Dr. Carson. After detailing his experiments, Dr. Williams draws the
following conclusions from them.

" 1. That a lung will not collapse from exposure to the atmosphere as long as respi-
ration is carrred on by the opposite one, and the auxiliary respiratory powers are not
restrained.

" 2. That a lung possesses for a time, independently of the influence of the dia-
phragm and intercostal muscles, if respiration is carried on by the opposite lung, a pe-
culiar motive power, the source of which I do not pretend to explain.

"3. That a sound lung soon regains its full power of expansion, when the pressure
of the exterior air is removed.

" 4. That air freelv and uninterruptedly admitted into both cavities of the chest si-
multaneously, through tubes of a certain calibre, will not collapse the lungs, if the auxi-
liary respiratory organs are unrestrained.

QJF THE FUNCTIONS OF THE LUNGS. 49

*' 5. That air admitted into both the cavities of the chest (of a middle sired dog) si-
multaneously through apertures of an inch and better in length in the intercostal paces,
will not collapse the lungs, provided the animal is allowed unconfined the use of his re-
spiratory organs.

** 6. That a sound lung never fills the bag of the pleura."

V. Of the Effects of Suspended Respiration on the Circulation. — From the experiments
which were made by Dr. Williams, of Liverpool, on this subject, he deduces the fol-
lowing corollaries :

1. The blood is obstructed in its passage through the lungs, on suspension of respira-
tion, while its circulation through the other parts of the body continues.

2. The obstruction of the blood in the lungs, on suspension of respiration, is not oc-
casioned by a mechanical cause. This is proved by the flow of blood through the lungs
being sudden! arrested, without any subsidance of this organ, while the circulation
was carried on vigorously through the other parts of the body, in the experiments de-
tailed by the author.

3. The observation of,bloodin the lungs, on suspension of respiration, arises from the
deprivation of pure atmospheric air.

4. The blood, which is found after death in the left auricle and ventricle, is the rem-
nant after the last systole, and the subsequent draining of the pulmonary veins.

5. The obstruction of blood in the lungs, on suspension of respiration, is one of the
principal causes of the vacuity after death of the system circulating arterial blood.

6. The immediate cause of the cessation of the action of the heart is a privation of
its natural stimulus, arising from the obstruction of the blood in the lungs. — (JInnals of
PhUos. Sept. 18^3.)

Of the changes induced on the Air and the Blood by Respiration*
Note W.

1. Of the production of Carbonic Acid during Respiration. — The experiments of Mr.
Ellis and others have led physiologists to conclude, that oxygen is not absorbed by the
blood in the lungs from the air, during respiration, but that the blood gives off its su-
perabundant carbon from the surface of the air-cells and the carbonic acid is thus form-
ed in the lungs themselves.

This mode of accounting for the changes induced upon the air and upon the blood
during respiration, has been very generally adopted in this country, while the former
mode of explaining the process (that which is given in the text) has still been received,
with various modifications, on the Continent.

It appears to us that the production of carbonic acid gas by the respiratory function
has been ascribed too exclusively to one of the above processes ; and that it has been
too generally viewed as altogether a chemical phenomenon. When the theory of the
absorption of oxygen was dismissed in favour of that which contended for the discharge
of carbon from the blood, either in its pure state or in that of a hydrate, no participa-
tion in the process, by which the carbonic acid is formed, was allowed to the previous-
ly received opinion : however, it still appears a matter of doubt how far either function
predominates ; tor we are inclined to think that both operations go on simultaneously,
and that, whilst a portion of the carbonic acid gas is given out from the, blood, already
formed, it is accompanied with another portion of free carbon, or an oxide of carbon,
or even with an hydrate ot the same sui -stance which combines with an additional quan-
tity of oxygen in the lungs, and thus forms the whole of the carbonic acid in question ;
and that, at the same time, a portion of oxygen is absorbed, which combines with the
carbon of the blood, and there generates the carbonic acid gas, or the oxide of carbon,
which forms a part of the matters discharged from the blood in the lungs. These pro-
cesses may vary, and either may predominate according to the state of the vital
influence at the time, under whose control they are immediately and completely placed.

This view of the phenomenon in question seems to be fully supported by the experi-
ments of Dr. Edwards of Paris. They prove that the carbonic acid gas does not form

G

50 APPENDIX,

instantaneously io the lung's through the action of the respired au>, but that it appeals
be secerted to a considerable extent, from the blood in the respiratory organs.

As to the quantity of this gas which is formed during respiration, different physiolo-
gists have estimated it differently. Godwin considered that for every 100 cubic inches
of atmosphere respired, there were given off 10 or 11 of carbonic acid. Menzies, from
experimentsmade with much accuracy, found the quantity of carbonic acid to be about
5 in the 100. Dr. Murray considered it to vary from 6 to 6.5. Sir H. Davy from 3.95
to 4.5. Messrs. Allan and Pepys from 5.5 to 9.5, They estimated the mean at about 8.
Dr. Prout found it to be about 3.45. Dr. Fyi'e about 8.5. The discrepancies which are
remarkable in these results of the experiments performed by these physiologists doubt-
less arose, in a great measure, from the different proportions of this gas, produced by
different individuals according to the state and developement of the lungs, and accord-
ing to the particular circumstances of the individual at the time of the experiment.

The influence which the state of the individual exerts upon the function was first
shown by the experiments of Dr. Prout and Dr. Fyfe. They proved that the carbonic
acid gas formed during respiration is liable to be very materially affected in its quantity
in the same individual, by various circumstances. It was formed in a minimum quanti-
ty during the night ; and the maximum quantity, which was generally produced about
noon, exceeded the minimum about one-fifth of the whole. The passions of the mind
were found to have a great influence over its production ; the depressing passions di-
minishing its quantity, and those of an opposite nature the reverse ; exercise, when mo-
derate, appeared to increase in some measure the quantity, but fatigue diminished it.
The greatest decrease experienced was from the use of alcohol and vinous liquors, es-
pecially when they were taken upon an empty stomach. In short, whatever diminished
the powers of life, as lo\v diet, mercurial irritation, &c. appeared from the experiments
of Dr. Prout and Dr. Fyfe to have the effect of diminishing the quantity of the carbonic
acid.

Dr. Crawford found the quantity of this gas was much diminished when respiration
\yas performed in a high temperature ; and Lavoisier and Saguin confirmed his obser-
vation. Nearly similar results to theirs were obtained from some experiments which
we performed in 1815 ; and from the data thus obtained we endeavoured* to account
for several of the most important diseases to which the inhabitants of warm countries
are liable. Similar experiments were afterwards performed in an intertropical cli-
mate, where we found the diminution of the quantity of carbonic acid to be considera-
bly greater than that which our experiments, in an artificial temperature of equal ele-
vation had furnished. This seems to be accounted for by the depressing influence upon
the nervous system which the atmosphere, loaded with moisture and malaria, may be
reasonably expected to produce. We also attribute a share of this discrepancy to the
increased function of the skin, which evidently co-operates, in hot climates with the
the lungs, and performs a subordinate respiratory function. We shall not pursue this
particular topic farther at this place, as we propose considering it more at length on a
Future occasion.

Reverting to the question whether the carbonic acid is formed ivit/iin the vessels, or
without them ; we must remark, that the evidence on the subject is very contradictory.
The experiments of Dr. Edwards, already referred to, show that the former process ex-
ists, at least to some extent ; and it is farther supported by the fact established by Ber-
zelius, that blood, especially its colouring part, not only absorbs oxygen very quickly,
but it also retains some part' of the carbonic acid thereby produced ; but whether or no
this absorption will take place through the parietes of the capillaries, is the point at is-
sue. The evidence for the absorption of oxygen through the capillary parietes is, how-
ever, nearly on a par with that for the excretion of the carbon ; if the vessels will per-
mit the transmission of the one, they may allow the transit of the other.

Those who contend for the passage of the carbon from the vessels, and who, conse-
quently consider thai the carbonic acid is formed externally as respects the vessels,
support their opinon by the experiments of Mr. Ellis, who first promulgated the doc-
trine. His experiments, were, however, performed out of the body, and under cir-
cumstances which entirely excluded the operation of the vital influence of the lungs and
of the system generally.

The must conclusive experiments in favour of this opinion are those performed by
Messrs. Magendie and Orfila. They found that phosphorus, dissolved in oil, and inject-
ed into the jugular vein of a dog, was expelled by the mouth and nostrils in the form

* These views were contained in a Latin Theses written at Edinburgh.

Of THE FUNCTIONS OF THE LUNGS, 51

6f copious vapours of phosphorus acid, which could hardly have been the case if the phps*
phorus acid had been formed within the vessels, as in this case, it would have remain-
ed in solution in the blood, it not being- a volatile substance. It might therefore be sup-
posed that the phosphorus was excreted in a state of minute division, from the vessels
of the lungs, and meeting, in this state, with the oxygen of the atmosphere, formed the
phosphorus acid in question. If this reasoning be admitted with respect to the phos-
phorus, it may be extended to the carbon contained in the venous blood.

From the contradictory eridence on the subject ; from the nature of that evidence ;
from the experiments of Dr. Edwards ; from various analogies that might be adduced,
could our limits permit, from the conformation of the lungs, and the extent of their
excreting and absorbing functions as evinced by experiments ; and lastly, from the con-
sideration that, although respiration takes place frequently, yet a very large portion of
air remains for a considerable time in the chest, thereby allowing the vitality of the
lungs themselves to be exerted upon the air received into them, — we conclude that
this organ may act in both the ways contended for ; and that, whether it act in one
manner or the other, more or less partially, the process is a vital one, and whatever
chemical laws may be employed in it, are under the control of the vital influence of
the organ, and modified by the ever-varying condition of this influence.

n. Of Absorption and Exhalation of Jlzote during Respiration. — Another subject of
much interest connected with the respiratory function, is that which immediately relates
to the absorption in the lungs of a portion of the azote contained in the respired air.
On this point also, the results of experiments have been various, and opinions respect-
ing them equally so. Dr. Edwards of Paris, who is well known as a very intelligent
physiologist, concludes, from different experiments, and from the circumstance of the
opposite results which they give, some indicating a diminution of the azote of the air,
others an increase of it during respiration, that this gas is absorbed into the circulation,
and at ter\vards discharged from it ; and that each of these actions is regulated by the
constitution, habit, and circumstances of the individual, and by the influence to which
he may be subjected, the absorption being to a small extent, while the exhalation is
considerable, and vice versa.

Independently of the satisfactory nature of the experiments whence Dr. Edwards
has drawn his inferences, there are many collateral proofs that may be brought to their
support, derived from the manifestations of the animal economy in health and disease ;
and we have little doubt that not only in azote, but that other gases, even those whose
presence in the respired air are accidental, may be also absorbed into, and discharged
from the circulation, in a greater or less quantity, according to the varying state or the
vital energies of the system.

III. Of the Jlssintildling Function of the Lungs. — The extent of the function of the
lungs has been a matter of doubt. Their principal office, namely, that of changing
venous into arterial blood, has always been admitted, although the nature of the pro-
cess has been disputed. Many physiologists, have in addition to this, attributed to
them an assimilating influence which is exerted chiefly upon the absorbed chyle and
lymph which the venous blood contains. This opinion appears correct. But the pro-
cess is purely a vital one. If the opinion of Dr. Edwards, respecting the absorption
and exhalation of azote be correct, this substance may be instrumental in the process.

A third function has been referred to this organ, viz. the formation of animal heat.
But however intimately related it may be with the respiratory process, it cannot be
considered a function of the lungs. It must, nevertheless, be allowed that the changes
induced upon the blood during respiration, are preparatory to the evolution of animal
heat ; and, although we contend that this heat is immediately the result of a manifesta-
tion of the vital influence of the ganglial system of nerves, exerted upon the blood
contained in the vessels to which these nerves are distributed, yet it must be admitted,
that the respraitory processes are requisite to its production, inasmuch as they produce
on the blood a change of properties which are requisite to excite this system, and as
this fluid, when thus changed, contains the materials necessary to, or is otherwise in a
suitable condition for, the manifestation of the influence which the part of this system
of nerves which is distributed to the blood-vessels exert.

52 APPENDIX.

IV. Of Pulmonary Transpiration. — The mucus membrane of the lungs gives oft' a
considerable portion of the watery secretion, which is carried out of the lungs, in the
form of vapour, by the respired air. This perspiration equally takes place when the
animal breathes a gas containing neither oxygen, hydrogen, nor azote ; it, therefore,
does not result from the combining in the lungs of the hydrogen contained in the
blood with the respired air, but is strictly an aqueous vapour slightly charged with ani-
mal matter — and is the production of a vital transpiration or secretion.

It has not been determined whether or no it be produced from the bronchial, or from
the pulmonary arteries. The question is difficult to decide, as an injection thrown in-
to either set of arteries arrives on the surface of the air-cells. Pulmonary transpiration
may contain, like secretions, foreign matters which have been conveyed into the circu-
lation ; the lungs acting as an organ eliminating them from the system. This has been
shown by some experiments of Magendie, and also in an experiment which we per-
formed, in which ten drachms of the oil of turpentine were chiefly discharged by the
lungs, from the circulation in the state of vapour, within twenty-four hours. The
large quantity of the turpentine vapour evolved from the lungs on that occasion, leads
us to suppose that transpiration takes place principally from the venous blood about
the time when the changes are affected in it by respiration. This experiment, alst*
seems to support the doctrine of the evolution of carbon from the blood.

Of the Production of Jlnimal Heat.

4

Note Y.

It ia not necessary to add at this place, much to what is contained in the text. We
then attributed the production of animal heat to the vital influence exerted by that
part of the ganglial system distributed to the arteries on the blood which they circu-
late.

Preparatory changes, however, take place in the lungs which are necessary to the
exertion of this influence, and to the evolution of heat ; but as it was contended tkat
those changes are more of a vital than of a chemical nature, so it is considered, that the
production of heat is more the result of the influence which the nerves of the vessels
exert upon the blood than of the change in the capacity for caloric which the blood
itself experiences in its passage into the venous state. The difference of capacity
which actually exists between venous and arterial blood is not sufficient, according to
the experiments of Dr. Davy, to form the basis of the chemical theory formerly re-
ceived, but the difference which actually does exist may be concerned in a subordinate
manner in the process.

Conformably with the opinion, as was first maintained on an occasion already allu-
ded to, we infer that the various causes which modify the production of animal heat,
act, 1st. immediately upon the organic system of nerves themselves, changing the con-
dition of their influence ; 2d, upon the blood, altering the nature and composition of
this fluid, and thereby rendering it unfit for producing the requisite excitement of this
system of nerves, and incapable of the changes which the influence of these nerves
produces upon its constituent parts , 3d, immediately through the cerebro-spinal sys-
tem, modifying the influence which this system imparts to the ganglial.

These different ways in which the vital influence, exerted by this system of nerves
in the production of animal heat, is modified, might have been illustrated by experi-
ments, and by reference to facts in comparative physiology and in pathology, if our
limits could have admitted of so great an extension of them. From what we have said
it will be perceived, that we view the production of animal heat more in the light of a
vital secretion than of a chemical phenomenon ; and that, like the other secretions and
nutrition, it proceeds from and is controlled by the vital influence of the ganglial sys-
tem of nerves.

OF THE CUTANEOUS FUNCTION. 53

Of the Cutane&ua Function.
Note Z.

I. Cutaneous Exhalation, or Insensible Transpiration. — In transpiration there appears
to be two actions, a physical one consisting of the evaporation in the air of the fluid
parts of the body ; and a vital action, giving rise to an excrenientitial exhalation, of
which the skin is the organ. This view of the subject is much contended for by DP.
Edwards ; but we think he has refined in an unnecessary manner in explaining it. The
cutaneous exhalation is doubtless an organic function of which the skin is the organ :
but, we conceive, that the skin must first perform its office before the physical action
can take place to any considerable extent ; in short, that as transpiration is pel-formed,
the physical law operates, and that both go on, the latter as a consequence of the for-
mer, pari passu, until an increase of the transpiration on the one hand, and an uncom-
monly dry state of the atmosphere, on the other, give us different results. When tiie
former takes place we perceive the formation of sweat, or the transpiration becomes
sensible : when the latter exists, then the phenomenon, for which Dr. Edwards and
some others have argued, as constituting one of the actions into which this function
may be divided, really supervenes to some extent. Thus we have witnessed, during
the Harmattan wind, which occasionally blows on the West coast of Africa, and which
is remarkable fov its dry ness, evaporation going on so rapidly as to give rise to very
inconvenient sensations, and even to serious disorders of the pai'ts which are usually
exposed to the air. In this case the evaporation exceeds the mere solution of the
transpired fluid in the surrounding atmosphere; and the parts of the body which are
subjected to its operation, have a portion of the fluids sent to the surface carried off
by it, in addition to what is exhaled by the natural and organic action of the vessels of
the skin.

The cutaneous exhalation contains a portion of the carbonic and lactic acids.

II. Of the Sweat or Sensible Exhalation — When we said, if the production of the ha-
litus or insensible transpiration from the skin exceed the evaporation of it in the atmos-
phere, sweat is formed, we stated the source of this fluid. It is, therefore, produced the
from same vessels as the insensible perspiration- But although this is the case, with re-
spect to their source, there is some difference between the nature or chemical constitu-
tion of the sensible and insensible cutaneous exhalations. The former is generally less
charged with carbonic acid than the former, but it abounds more with the salts usually
excreted from the system.

A careful view of the functions of the skin throughout the different classes of animals,
leads us to conclude that it performs operations which hold an intermediate place be-
tween those of respiration and elimination, — that it partakes of the character of a respi-
ratory and of an eliminating organ.

1. It is a Respiratory Organ — This is shown by the circumstance of this function be-
ing performed in the lower order of animals by the surface only; and by the gradation
observed from these up to the higher orders, and by the gradual perfection at which
the respiratory organ arrives in ascending the scale of animal creation. In the
higher animals the respiratory apparatus becomes more and more distinct, and the func-
tion depending upon it more and more limited to appropriate organs; however, the
same type which characterizes the lower orders, and is most remarkable in them, is still
preserved throughout the whole series of the animal scale, although it becomes gradu-
ally, and nearly, but not altogether lost. Thus in man, the lungs perform the chief re-
spiratory process ; but, even in him, the respiratory function of the skin is remarkable,
Carbonic acid gas is produced from the cutaneous surface, transpiration also takes place
there ; and this respiratory act of the skin becomes more or more remarkable under
circumstances which diminish or partially obstruct the respirator}' process of the lungs.
Thus we found that the quantity of carbonic acid gas, formed in the lungs in a given time
and in the same individual, was about one-third less in a hot climate than in a cold one ;
this was about the average result of our experiments: whilst we observed that the respira-
tory function of the skin, both as respects the quantity of the insensible transpiration and

54 APPENDIX.

the formation of carbonic gas, was very remarkably increased.* In a Negro, as far as we
could infer from experiments performed on a single limb, the respiratory function of
the external surface of the body was much greater, and the quantity of carbonic acid
formed in his lungs much less than in our own case although our size and weight were
equal. Hence we were led to infer that, in this race of the human species, the skin
performs a much greater supplementary function to that of the lungs, than in the in-
habitants of cold or temperate climates.

In two cases which came under our observation, in which the lungs were partly de-
stroyed from an imposthume, and the side of the chest was consequently contracted,
the cutaneous functions were afterwards very remarkably increased. Were it consist-
ent with the limits of these notes, many facts illustrative of this particular function of
the skin, as it respects the inhabitants of cold, temperate, and hot climates, might be
adduced.

2. The Skin is an Eliminating Organ. — Richerand' has so fully illustrated this func-
tion of the skin, and contrasted it with that performed by the kidnies, that it is unneces-
sary to say any thing respecting it, at this place. The chemical analysis of the perspir-
ed fluid, given in the next chapter of the Appendix, will show to what extent it pep-
forms an eliminating office.

Of tte Fluid?
Note AA.

In .addition to the classifications of the fluids, we may mention that adopted by M.
Chaussier. He divides the fluids into five classes : those produced by the digestive
process — the chyme and the chyle; the circulating fluids — the lymph and the blood;
the exhaled or perspired humours; the follicular humours, and the glandular hu-
mours.

M. Adelon, the able and eminent pupil of M. Chaussier, has proposed another classi-
fication, which possesses some advantages over those which have preceded it. It is
also simpler and more natural. He divides the organic fluids into those of Maorgtion,
the fluid especially Nutritive, and the Secreted Humours.

1° The Absorbed Fluids are the chyle, the lymph, and the venous blood. These are
taken up and conveyed by the lymphatic and venous class of vessels, and ultimately
become assimilated with, and, indeed, concur to form the fluid specifically nutritive.
Thus the chyle, after a longer or shorter course, mingles with the lymph, both are
poured into the venous blood, and when they arive at the organs of respiration, they
become perfectly united, being converted into the nutritive fluid by the functions of
those organs.

2° The Fluid especially Nutritive.-— The three fluids constituting the first class being
changed in the respiratory organs into that which can alone nourish the body, thus
constitute the second class, which in its turn, furnishes the materials of all those em-
braced by the third. The second class is, therefore, the arterial blood only, which be-
ing fully perfected in the lungs by the action of the atmospheric air, and circulated
throughout the body, furnishes the materials of nutrition and secretion, and stimulates,
and contributes to preserve the functions of the living solids, and in conjuncton with
these solids,f produces the calorification of the animal system.

3° The Secreted Humours — This class may be divided into three orders, according to
the forms of the secreting organs which produce them ; namely, into Exhaled or Per-
spired Fluids, Follicular Humours, and Glandular Humours.

Jl. Exhaled or Perspired Humours. — These are numerous, are produced in the form
of vapour, and they differ from one another in their physical and chemical properties,
and in the purposes which they fulfil in the animal economy. They are, moreover, dis-

* The experiments whidi were made in order to ascertain this from the want of the
means and proper facilities were not performed upon the whole body, they were made
only upon a single limb ; but the results were very decisive and remarkable.

f By living solids is here meant all sensitive and irritable parts — all those which are
influenced by an irritating cause.

CLASSIFICATION OP THE TLUID9. 55

linguished into those which are taken up by lymphatic or venous absorption, and carri-
ed back into the torrent of the circulation, and into these which are entirely thrown out
of the body ; the former being usually denominated recrementitial, the latter excrementi-
tial, from these circumstances.

The recrementitial fluids are all produced in cavities or in situations that have no ex-
ternal outlet. The following enumeration includes all the fluids appertaining to this
genus :— 1° Serona fluids, as those which are exhaled on the surface of the arachnoid,
of the pleura, of the pericardium, the peritoneum and the tunica vagmalis.— 2° Tho
Synovia. 3° The ncrosity of luminous tissues.— ±° The/a* formed in the adipose tissue.
—5° The marrow, or medullary juice.— 6Q The colouring humour of the skin, placed un-
der the epidermis.— 7° The colouring humours of the ins, of the uvea, and of the cho-
roid.— 8° The three humours of the eve— the aqueous, crystalline, and vitreous — 9° The
Ivmph of Cotug?io.—lQ° The fnanmtr of the lymphatic glands, a gelatmo.albuminous fluid,
existing in the spongy tissue of their organs.— 11° and lastly, the fluid perspired on the
internal surface of all the vessels, the existence of which may be doubted, as it is next
to impossible to demonstrate its existence. In addition to the perspired recrementitial
fluids may be added those which exist in the human ovum, viz. the amniotic fluid ; the
-water of the chorion, which exists between thechorion and amnios, only during the early
months of pregnancy ; and the -water of the umbilical vesicle, which may be compared to
the yolk of an egg, and which some physiologists believe destined to nourish the em-
bryo before the developement of the placenta.

The excrementitial perspired fluids are all thrown otf' from the external surface of
the body, and from the mucous membranes which have a communication externally by
means of the natural outlets, and which may therefore be considered as merely form-
ing parts of the external surface.— lc Those fluids -which perspire from theski.n, as the cu-
taneous insensible perspiration, and the humour constituting the sweat— 2° The fluids
per spired from the respiratory apparatus ; these differ somewhat in different situations, as
in the nasal cavities, in the trachea, and bronchia- — 3Q The humours exhaled on the sur-
face of the digestive canal. — 4° Those humours exhaled on the internal surface of the uri-
nary apparatus, viz. on the internal surface of the ureteis, the bladder, and urethra. —
5° The fluids exhaled from the genital organs, namely from the internal surface of the
vesiculx seminales and ejaculatory conduits, in the male, and from the nterus and va-
gina in females (the menstrual flux and the lochise.)

B. The Secreted FoUicular Fluids are those formed by a particular secreting organ
called follicular. They are all excrementitial, and consequently are formed on, and
eliminated from, the two external suifaces of the body — the skin and mucous mem-
branes. They consist of — 1°. The sebaceous humour of the skin. — 2° The cerumen ;
the humours of Meibomius. — 3° The humour of the caruncula lachrymalis. — 4° The hu-
mour secreted at the base of the glans penis in the male, and on the surface of the
vulva in the female. The humours secreted by the follicles in the mucous surfaces are
generally characterized by the generic term mucous. They are distinguished into the
mucus of the respiratory organs, the mucous of the digestive apparatus, of the urinary ap-
paratus, and of the genital organs. The humours formed by the prostate, and by the
glands of Co-wper — compound and glandiform follicles — are usually referred to the last
mentioned in this enumeration. The fluid secreted by the tonsils is generally classed
\vith those of the digestive organs.

C. Lastly. The Secreted Glandular Humours are the production of glandular organs.
They are — 1° The lachrymal fluid. — 2Q The salivary fluid. — 3° The pancreatic AM-
mours.— 4° The bile. — 5° The urine — 6° The semen / and 7Q the milk.

It may be remarked generally with respect to the humours, that the degrees of fluid-
ity which belonging to them, vary greatly from a state of gas or of vapour, to that of
semi-fluidity : — they have, moreover, all the physical conditions constituting a fluid
body. Their fluidity, however, does not result from the general forces of matter, but
from those of life. Indeed the vital influence modifies their physical form of existence,
in a more or less marked manner, as long as they continue subjected to its operation.
Prom this source also they are imbued with a certain influence, the presence of which
indicated by the continuance, for a time, of the specific characters of each. This in-
fluence, being no longer, renewed when they are removed from the body, soon be-
comes dissipated, and the secretion which, while within the sphere of the animal sys-
tem and for a short time afterwards, possessed an emanation of the vital influence suffi-
cient to give it certain characters, and to preserve it from the chemical changes to
which its constituents are naturally prone, at last falls into a state of dissolution, as u ic-
quivocal as that evinced by the te'xtures of the body. In confirmation of this view, we
need only refer the Physiologist and Pathologist to the comparative condition of the
more perfectly elaborated secretions immediately after their formation and excretion.

55 .APPENDIX.

and after periods of various duration have elapsed from the time of their discharge from
the body.

Finally, we may remark that the fluids, being composed of molecules moving with
facility on each other, cannot, as the solids, be traced to constituents of an elementary
nature. They can only become the subject of microscopic research in our endeavours
to trace the nature of their constitution : by this means we can merely learn that they
are generally composed of globules, swimming in a fluid substance, and whatever be
the fluid employed, we perceive only globules suspended in an amorphous liquid. It
should, however, be remarked that, as we find in some solids merely a concreted amor-
phous substance containing no globules, as in the cellular tissue for example, so we
perceive some fluids destitute of globules and formed only of an amorphous substance,
which is perfectly fluid. In other solids and fluids, on the contrary, we h'nd both glo-
bules and an amorphous matter, which is concrete in the former and liquid in the other.
But these globules vary greatly, both in solids and in fluids, and even in the same part,
according to age ; those of the blood, for instance, are composed ci a solid central part,
and of an external envelope which is coloured; those of the chyle appear to be the
same as the central part of the former without its coloured envelope ; those of the mus-
cular fibre seem to be the same as those of the blood ; those of the brain and nerves are
smaller than the foregoing ; and those of the kidneys are smaller than those of the
spleen. — During the first epoch of conception the globules are not visible ; they, how-
ever, soon form, and become more and more distinct. See on this subject Physiologic
de I'Homm*, par-JV. P. ^Idelon. Vol. 1. p. 116.

Of the Blood.
Note BB.

I. Of the fimgtt colourless Globules of the Hlood.^-The researches of Sir Everard Home,
and Mr. Bauer, (Phil. Trans, for 1820,) seem to lead to the following conclusions re-
specting these globules.

1. That the milk-like fluid, the produce of digestion (cliyle) which is found in the
lacteal vessels and glands, contain an infinite number of white globules, chiefly of a
minute size.

2. These newly discovered minute globules are __ * part of an inch in diameter.

3. That the chyle contains also some white globules of the size of the red globules of
the blood.

3. Mr. Bauer supposes that the full sized globules acquire their form in the lacteal
glands.

5. Sir Everard Home considers that the globules of the blood receive their red hue
in the vessels of the lungs.

6. That lymph or fibrine, whether taken from an inflamed surface, from the buff of
\vhat is commonly called inflamed blood, or from the slowly formed layers of aneuris-
mal tumours, consists of innumerable white globules, much smaller than those which
constitute the red globules of the blood, and similar to those minute globules already
described.

7. That these small globules constitute the substance thrown out in inflammation.

8. That they are held in solution in the st rum, and consequently are only brought
into view in the act of coagulation.

9. That these globules, as well as those which subsequently receive the red colour,
are the produce of digestion, and are formed in the pyloric portion of the stomach, and
in the duodenum, surrounded by a glairy mucous, which is met with in these parts.

M. Prevost and Durnas* agree with Sir Ev. rard Home, as to the form and structure of

* The microscopic observation of the blood satisfied these gentlemen, that this liquid
during life, was nothing else than the serum, holding in suspension small, regular, and
insoluble corpuscles. These are uniformly composed of a central colourless spheroid,
and of a species of membranous bag1, oi' a fed colour, Surrounding this spheroid, from
which it is easily separable alter death. The central body is white, transparent, of a
spherical form in animals with circular particles ; of an ovoid form, in those with ellipti-
cal particles. Its diameter is constant in the first, but it varies very perceptibly in the

OF THE COAGULATION OF THE BLOOD. 57

the globules of the blood ; but they do not admit with him that the red globules undergo
a rapid change after they escape from the vessels, or that the colouring matter which en-
velopes the central spherical body separates as soon from the globule, as thirty seconds
after the blood has issued from the vein. They, however, agree with him in saying,
that these central spheres (the smaller globules) unite themselves in filaments, which
differ in no respect from the muscular fibre. They observed also small globules in the
milk, in pus, and in the chyle ; and they consider "that those of the former fluids have
been, and these of the latter are to be, surrounded by the colouring matter of the
blood.

Messrs. Prevost and Dumas found the globules of the blood to be circular in all the
mammalia ; and in their size to vary in different animals ; they are. smallest in the goat.

The globules are elliptical in birds, and they vary considerably in size in this class of
animals. This variation is chiefly in the great axis of the globules. They are ellip-
tical also in all cold-blooded animals.

IF. Of the. Coagulation of the Blood, — On this part of the subject before us, we cannot
enter minutely. We will merely state, as briefly as we can, those inferences at which
we have arrived, after a careful "examination of the phenomenon itself, under various
circumstances, and of the different opinions entertained respecting it.

1. According to the observations of Treviranus and Kolk, whose observations on this
subject have been extended and faithful, the particles or globules of the blood possess
a rotatory motion during life, and this motion continues until the phenomenon of coa-
gulation takes place.

2. That this motion of the globules is the cause of the blood's fluidity.

3. That the motion of the globules is the consequence of the vital influence emanat-
ing from the glanglial nerves distributed in the parietesof the vessels in which they cir-
culate.

4. That the cause of the coagulation of the blood is not to be found in external agen-
cies but in the loss of that emanation, (proceeding from the organic nerves distributed
to the coats of the vessels,) of the vital influence with which the globules are en-
dowed.

5. That the presence of the air, especially of the oxygenous portion of it, promotes
this phenomenon.

6. That when coagulation commences at any point of a mass of blood it is rapidly
propagated throughout the whole ; this may arise from the cause being co-ordinate, or
nearly so, throughout the whole.

second. It manifests also a great disposition to form aggregates or ranges, in the form
of a string of beads.

The coloured portion appears to be a kind of jelly, easily divisible, but insoluble in
water, from which it may always be separated by repose/ It is likewise transparent,
but much less so than the central corpuscle ; and the fragments arising from its division
are not susceptible of regular aggregation. As the attraction, which keeps the red
substance fixed round the white globules, ceases at the same time with the movement
of the liquid, these globules can then obey the force whvh tends to unite them, and to
form a net-work, in whose meshes the liberated red colouring matter gets enclosed ;
and thus produce the phenomenon of coagulation. If the eoagultim be exposed to
a stream (jf water, the colouring matter is washed away, while the aggregate formed
by the white globules remains in the form of filaments, in which may be recognised, by
means of the microscope, the aspect and structure of the muscular fibre.

Three animal substances ought, therefore, to fix our attention : these are, the albu-
men of the blood, the white globule, and the colouring matter which envelopes this.
With respect to the colouring particles of the blood, these chemists suppose that it. is
formed of an animal substance, in combination with a peroxide of iron. The colourless
globules they consider to be coagulated allnimcn. They have examined the proportion
which the white corpuscles and red matter together bear to the rest of the blood, in a
great variety of animals ; and they find them most abundant in birds, next in the mamma-
lia, especially the carnivorous mammalia ; and they are least plentiful in cold-blooded
animals. In man they consftute about one hundred and twenty -nine parts by weight,
per thousand. They are iiiore abundant in arterial than in venous blood ; one thousand
parts of the arterial blood of the sheep, dog, and cat, contain ten parts more of these
particles than blood taken from the veins. The serum is identical in both.

H

58 APPENDIX.

7. Neither the heat of the body, nor the strength of the circulation, are causes of the
bloods's fluidity, they are both results of one cause, viz. the vital energy of the vessels ;
both are co-ordinate, and both as well as the phenomena of coagulation itself, are de-
pendent on this one source.

8. That coagulation occurs sooner in venous than in arterial blood, and that coagu-
lation of arterial blood is still longer delayed if it be prevented from leaving the arte*
lies.

9. That coagulation takes place the sooner after the blood is removed from the vital
sphere of the s;, stem, the weaker the vital energy to which it was subjected whilst cir-
culating in the system.

10. That the weaker the vital energy, and, consequently, the quicker the coagula-
tion, the more lax is the coagulum which is formed.

11. That, on the same principle, coagulation is more slow, and the coagulum more
firm, according as the vital influence of the vessels is more energetic.

12. That the quantity of globules modifies these results ; a large proportion also of
these globules indicates great energy, and vice versa.

13. That as the central globules retain their coloured envelopes, during their circula-
tion in the blood-vessels, and lose them soon after removal beyond the sphere of the vi-
tal influence of these vessels, and as this is a part, and indeed the first part of the act of
coagulation, so we consider, that it is in consequence of the vitality emanating from the
interior of the vessels into the blood, that the coloured envelopes of the central globules
continue to surround them ; and, consequently, that the separation of the envelope
from the central globule is the result of the loss of the chief portion of that vitality
which proceeds from the containing blood vessels ; and, as this loss of vitality may be
reasonably supposed to be quickest where it has been originally the least, therefore the
seperatioii of the envelopes and the coagulation will be the quicker the weaker the vi-
tal energy, and vice versa ; and the coagulum will be the more lax.

14. That the loss of the vitality, emanating from the vessels, and, consequently, the
loss of their envelopes, disposes the central globules to attract each other ; and that in
the exertion of this contraction they dispose themselves into reticulated fibres, which
entangle the colouring matter and a portion of the serum ; and thus the clot is formed.

15. It would appear that the central globules continue to retain, in the fibres which
they form, in the act of coagulation, a small portion of the vital enmaation with which
they were endowed ; in as much as the fibrous part of the coagulum evinces phenome-
an approaching to those denominated irritable ; and that it is the loss of the chief part of
the vitality, and not the whole of it, which occasions the separation of the coloured enve-
lopes from the central globules.

16. That the firmness of the coagulumancl the irritable phenomena e vinced by its
fibrous part are proportionate in degree to the vital energies with which the vessels are
endowed by the ganglial nerves distributed in them, and to the emanation which the
globules themselves derive from this source.

17. That the vital emanation, proceeding from the ganglial nerves distributed in the
vessels, affecting the globules in this manner, and giving rise to these phenomena, has
been the cause of, and has countenanced, the hypothesis of the vitality of the blood —
a vitality which does not originally belong to it, which it possesses in a diminished de-
gree, and which is an emanation from a different source, which source is efficient in the
formation of the blood itself, and bestows on it through the medium of the vessels con-
taining it, the chief properties which this fluid evinces in health and in disease.

18. That when the vitality of the blood-vessels is greatly diminished, as in purpura
haemorrhagica, scurvy, and in other diseases, coagulation either does not at all take
place, or it takes place very quickly and the coagulum is weak, lax, and resembling
cruor. Under such circumstances, the envelopes separate rapidly from the central glo-
bules, because the vitality of the vessels is scarcely sufficient to continue them in con-
nexion, even when circulating through the vessels themselves ; coagulation takes place
quickly, because the motion impressed upon the globules by the vital energy of the
vessels, owing to the defect of this energy, is soon lost, and because the separation of
the envelopes from the globules takes place almost instantly ; and the coagulum which
is formed is weak, or it does not form at all, because the vitality of the globules is in-
sufficient to dispose to an energetic attraction, or even to any attraction between the
central globules.

19. and lastly. Opposite phenomena result from the increased energy of the vital
functions of the ganglial nerves distributed to the blood-vessels.

OF SECRETION AND EXHALATION. 59

HI. Of Transfusion of Blood.-— Messrs. Prevost and Dumas found that, after bleed! ng
an animal until all organic actions ceased, and injecting-, within a few minutes after-
wards, the warm blood taken from another of the same species, until a quantity equal
to that taken wag restored, the animal gradually revived and took nourishment, and
entirely recovered, if the operation was perfectly performed.

If, however, the blood injected was taken from an animal of a different species, pos-
sessing globules of the same form, but different in dimensions, the animal was very im-
perfectly revived, and could be rarely preserved beyond six days. The pulse became
in these frequent, the temperature fell remarkably, if not artificially preserved, while
the respiration retained its natural frequency. Immediately after the operation, the de-
jections became mucous and bloody; and preserved that character until death.

If blood with circular globules, was injected into the veins of a bird, the animal ge-
nerally died before the operation was completed, in very violent and nervous convul-
sions.

Transfusion of blood from the cow or sheep into the veins of the cat or rabbit, was
followed by the recovery of the animal in a number of cases.

The blood of the sheep excited in the mallard duct the most violent and rapid con-
vulsions, which were immediately followed by death, as was observed to follow the in-
jection of the first syringcful inland-birds. (Biblioikeque Univers. Juillet, 1821.)

Of Secretim and Exhalation.
Note CC.

Opinions have been various respecting the mechanism provided for the performance
of exhalation and secretion. One class of physiologists contends for a separate order of
very minute capillaries proceeding from those carrying red blood, which they call ex-
halent or secretory capillaries, and devoted to these functions. Belonging to this class
we may reckon Haller, Hewson, Scemmering, Bichat, Chaussier, Alard, &c. As these
vessels cannot be demonstrated, there existence is denied by Mascagni, Prochaska,
Richerand, Magendie, and others, who argue, that these functions take place in the
sanguineous capillaries through the* medium of organic lateral pores. The fact ap-
pears to be that the evidence for a separate set of capillaries is equal to that for the ex-
istence of organic pores in the capillaries carrying red blood ; it is not easy to demon-
strate the presence of either; whilst both the one and the other may prove a sufficient
medium through which the processes will go on under the influence with which the
capillary vessels are endowed. The existence and efficacy of this influence is sufficiently
manifest, although the more minute intruments by means of which it operates, can-
not be satisfactorily demonstrated to our senses.

With respect to secretion, the state of opinions and of our knowledge as to the man-
ner in which it takes place, or rather the mechanism provided for its performance, is
similar to what we have shown to exist on the subject of absorption and on that of the,
minute capillaries. In stating the opinions on these subjects, and those lately espoused
by M. Alard. we gave the views of those who contend for the existence of minute
lymphatics running into the venous capillaries, in a similar manner to that in which ex-
halent vessels are supposed, as stated above, to proceed from the arterial capillaries.
But the latter set of vessels has been as little seen as the former. This, however, in a
matter of this nature, is not a sufficient proof against their existence. Other physiolo-
gists, on the other hand, contend that exhalation and secretion take place through
means of pores analogous to those which are supposed to be instrumental in the phe-
nomena of absorption ; and that the process is entirely one of transudation. But the
same objection may be offered against the existence of pores as to that of the exhalents
or secreting capillaries in -question.

We believe that the precise way in which exhalation and secretion take place can-
not be readily demonstrated to the senses, — that the one apparatus may explain the
process as well as the other, — that secretion as well as absorption, are not mechanical
processes, although there are apparatuses, or subordinate instruments, provided for
their performance, and that they are essentially vital operations, and under the control
of the vital influence with which the capillaries themselves, and the organs to which
they belong, are endowed.

As to the question of pores, it must be granted that the solids of the body, and the

60 APPENDIX,

parietes of the vessels, are all porous ; it is only with respect to the extent and mag-
nitude of the pores that the question can be entertained. Those who contend for the
existence of separate and subordinate sets of capillary vessels cannot deny the exis-
tence of pores, for if they do not exist both on the surfaces and in the textures whence
these capillaries are supposed to originate, how could they obtain the fluids circulating
in them ? On the other hand, those who contend for the existence and functions of
pores cannot deny the existence of minute absorbents or lymphatics, for they can be
demonstrated, to a certain extent, as respects the minuter ramifications, and, in a satis-
factory manner, as regards the more considerable brandies. It appears to us that
both species of organization exist to a greater or less extent in different textures, and
secreting- organs.

Each secreting viscus, is supplied with a distinct ganglion, plexus, or both ; these
preside over the secreting function, and the functions of some of these ganglia are in-
fluenced by the operations of the cerebro-spinal system ; as, for example, the secretion
of the lachrymal gland is increased by the influence which the nerves of the latter sys-
tem convey to the ganglion which supplies it, and is the chief source of its functions.

Of Nutrition.
Note C. C. and S.

As we have already seen, in the notes on the capillary system and on secretion, the
function of nutrition has been explained, by one class of Physiologists, by supposing
the existence of nutritive capillaries, and by another, by means of. organic pores, with
which they endow the capillary vessels circulating red blood, and to which they com-
mit the exhalent, secreting, and nutritive functions. The first of these hypotheses
supposes that nutrition takes place in minute colourless vessels, which proceed in a
more or less tortuous direction from the arterial capillaries, absorption proceeding
through the medium of a similar set of colourless vessels continuous with the former,
which run into the venous capillaries, and thus the nutritious molecules are always cir-
culating within colourless capillaries, which, with the nerves and larger capillaries,
constitute the basis of the different textures.

Mascagni supposes that the arterial capillaries, at the point where they change into
veins, are provided with exhalent pores both for the purposes of secretion and nutri-
tion ; and that there every where exist the orifices of minute absorbent vessels, com-
ifciencing in the latter description of pores, in order to take up the nutritive molecules.
The elementary tissues consist, in his opinion, of the particular class of absorbent ves-
sels, which contain the molecules as long as they are a part of the textures, and which
by their union, lorm the most simple membranes.

' These hypotheses do not differ very materially. Both contend for the existence of
very fine capillaries which attract the nutritive molecules, and contain them in a state
of progressive circulation, as long as they form constituents of the textures : these
molecules being afterwards carried onward in succession into the branches of the ab-
sorbent lymphatics and into the veins. In the first of these hypotheses, the nutricious
particles are supposed to circulate in the finest of the vessels proceeding from the ar-
terial capillaries ; in the second, the process is ascribed to the most minute radicles of
the absorbents ; but both agree in considering the molecules constituting the mass of
the textures to be contained in colourless vessels, and to be in a state of continual cir-
culation.

The opinion of Bichat on this subject is somewhat different. According to him,
each molecule of these constituting1 the textures of the body is placed between the
orifices of two vessels : one, a nutritive exhalent orifice, which has deposited the mole-
cule, the other a nutritive absorbent orifice about to absorb it.

Prochaska, who conceives that the arterial capillaries are continued directly into
veins, considers that nutrition takes place, in consequence of the porosity of the ca-
pillaries, and of the general permeability of the substances constituting the mass of
the structures. M. Richerand espouses a similar opinion, but he seems to allow ail
organic property to the pores which lie ascribes to the capillary vessels.

Opinions respecting the mechanism of nutrition, or the manner in which it takes
place, can only be theoretical. We have not the means of demonstrating the exis-
tence or non-existence of either the one or the other mode of organization contended
fov: each may of itself be sufficient to explain the phenomenon, as far as respects the

OP NUTRITION. #1

apparatus required for the process, but it is only the apparatus. The function itself 13
purely a vital one. It presents us with a continual motion of a double nut are — a con-
tinual attraction and decomposition of" material molecules. In the most simple ani-
mals, as the polypus, these processes go forward without any previous preparatory func
tion : the aiiimai imbibes, in a direct manner, similar molecules of matter to those of
which it is its formed from the surrounding1 medium, and again exhales them in a man-
manner equally direct. In these there are no vessels destined for the purpose of circula-
tidn and nutrition, yet they present the phenomenon of irritability ; and on examina-
tion, with a microscope, their structure appears almost homogeneous, with the excep-
tion of globules entirely similar to those which are observed in the ganglial nerves of
the higher animals. As these are the chief mai'ks of internal organization which can
be detected in the very lowest of the animal kingdom, and as we must conceive that
the organization must be instrumental inthe nutrition and operations of animal bodies :
and as, moreover, we perceive that the perfection of the organization or material appa-
ratus is commensurate with, and has an evident relation to the extent of the vital opera-
tions which it performs, so it seems reasonable to suppose that this organization,
which is the only one to be detected in the very lowest of animals, is the chief
and indeed only instrument of the limited function which these animals perform ; and
that, as a similar, but more perfect organization presides over the nutritive function
of the highest animals, so this presides over that of the lowest, without the assistance
of the more complicated capillary apparatus assigned by some physiologists to the for-
mer; and if a distinct set of subordinate capillary vessels be not requisite to the nutri-
tive function in the one, we may allow that it takes place in the other, under the domi-
nion of the more perfect nervous organization to which we have assigned it, without
the existence of the more complicated capillary apparatus for which some contend.

Concluding, therefore, that as the nervous globules demonstrable in the very lowest
animals are the only organization which they evince, that organization must have a de-
terminate object or function which it performs under the control of the vitality with
•which it is allied, and which all animals possess; and that nutrition and irratibility are
the" only organic actions which these animals perform, so it must inevitably follow that
these actions result from the vital influence allied to the particular organization in ques-
tion, and that the nervous globules, constituting the only marks of internal organization
possessed by these animals, attract from the surrounding medium, in consequence of the
vitality with which they are allied, these molecules of matter corresponding1 to those
forming the structure of the animal, which come within the sphere of their influence, and
retain them for an indefinite time, without either the medium of exhalent or absorbent
vessels. Now, as the same type, especially as respects the nutritive functions, may be
observed throughout the whole animal creation, and as we can trace nervous cords,
formed of globules similar to those already ascribed to the lower, and indeed to all ani-
mals, throughout almost the whole of their bodies, is it not reasonable to suppose that
similar globules exist in all the simple textures in a more diffused form — that the glo-
bules constituting the organic or ganglial system of nerves become more disseminated
amongst the molecules of the textures in the course of their distribution with the ca-
pillary vessels, or of their more direct ramifications and terminations in the textures
themselves ? If this be granted — and it scarcely can be denied, for it has been demon-
strated in different orders of animals, — and as it has been shown that these nervous
globules are present, in a more or less organized form, throughout the whole animal
creation, it i-may consequently be inferred that the same function which we have as-
cribed to them in the lowest animals should be extended to them in the highest. This
is conformable to the laws characterizing the animal economy.

As we have contended in another place, conformably with this opinion, that the gan-
glial nerves in some one or other of their forms of existence, are present throughout
every part of the" body, that they preside over digestion, nutrition, secretion, &c. and
are more nearly allied than any other texture with the vital influence which the body
exhibits, so we now conclude that the globules constituting the ganglial system, being
allied with vitality, and being distributed in different fonns of connexion to the various
textures of the body, exert, in consequence of the vital influence with which they are
endowed, a vital attraction on those molecules of matter which come within the sphere
of their influence ; that the force of this attraction, and the manner in which the ma-
terial molecules are arranged In order to form the different textures of the body, result
in a great measure from the influence proceeding from the form, the number, or the
condition of these globules in the textures which it is their office to perpetuate ; and
that the chief office of the digestive, the respiratory, the animalizing, and the circu-
lating processes, is to present the materials, whence the different textures are pre-
served, in a fit state for the exertion of this vital attraction ; and that the principal ope-
ration performed by the capillary vessels is to convey these materials within the spher;

62 APPENDIX.

of this attraction ; and, so that this is performed, it matters but little whether or no
these vessels accomplish it by means of subordinate nutritive capillaries destined to the
circulation or deposition of the nutritious molecules, or by means of organic pores,
with which the parietes may be provided.

But, whilst we suppose that the function of nutrition may thus take place in conse-
quence of a vital attraction, resulting in the manner which we have explained, and ex-
erted exterior to and independently of the vessels, and whilst we consider this expla-
nation to be supported by the nutritive actions of the lowest animals, yet we would by
no means exclude the influence of that part of the ganglial nerves distributed to the ca-
pillaries, from a part in the operation, more especially in the higher classes of animals.
Indeed it seems difficult to suppose which of those in the higher animals — namely,
whether the nervous globules distributed to the simple textures, and placed beyond
the capillaries, or those constituting the nervous fibrilhe which surround them, —
are most efficient in the nutritive process. An intimate view of the subject would
suggest, that in man and the more perfect animals, the latter organization is the
more active of the two iu the operation in question ; and that the capillary vessels, in
consequence of the ultimate nervous structure which surrounds them, and of the vital
influence which this structure exerts, secrete from the fluid circulating in them certain
materials in a similar manner to that in which they perform the other secretions in se-
creting organs, and by means either of appropriate vessels or pores.

As it has been shown that the blood consists of minute globules, or corpuscles sur-
rounded by a coloured envelope circulating in a ma'ss of fluid, and that the simple solids
of the body are constituted of similar corpuscles, in a state of intimate or vital attrac-
tion, as those of the blood, when they ai-e separated from the envelopes, so it may be
inferred, that a part of the function which the ultimate distribution of the ganglial
nerves perform on the capillary vessels, is to secrete similar corpuscles, from the blood
circulating in them, to that which the texture possesses in which the operation takes
place ; and that this having been accomplished, the vital attraction is preserved either
by means of the influence with which these corpuscles are endowed, as a consequence
of the previous process of animalization which they have undergone, or of the influence
exerted upon them after they leave the vessels by the nervous globules and fibrillas
disseminated in the textures, or perhaps by both species of vital action, either the one
or the other acting more or less* partially according' to the nature of the particular tex-
ture in which the process takes place, and according to inappreciable and fortuitous
causes.

Hence it will be perceived that nutrition is essentially a vital operation, that it is
placed under the control of the extreme ramifications of a particular system, to which
we have referred all the vegetative or organic operations which characterize the ani-
mal kingdom ; that it is performed in all animals except the very lowest, through the
medium of circulating organs, and in the highest, as a consequence of certain prepara-
tory processes ; that it requires in man and in the higher animals a capillary circulation
for its performance, but that neither of the capillary apparatuses which have been con-
tended for is sufficient of themselves to accomplish it, although the most simple of
them under the dominion of the vital influence of that particular structure which we
find every where disseminated where there is life, is all that is requisite as the material
instrument of the process ; and lastly, and as a consequence of the foregoing position*
that nutrition is modified, controlled, increased, or even annihilated, either generally
or in particular parts of the body, by the state of the vital influence allied to the mate-
rial organization, to which we have already imputed it, according as this particular or-
ganization in its centres and ramifications throughout the animal frame is generally or
locally affected.

Of the Dedication of the Optic Nerves,

Vicq D'A.zyr, found, on examining with the microscope, an horizontal section of the
optic nerves of the human subject, after it had been hardened in alcohol, that the me-
dullary fibres occupying the exterior side of the optic nerve, proceed in a direct man-
ner from the optic thalamus to the eye of the same side ; and that the place of union
presents a homogeneous tissue The Wenzels came nearly to the same conclusion
from their observations, but remarked, in addition, that while the fibres of the exterior
side of the nerve go immediately to the eye of the same side, those fibres, placed in its
interior side of the nerve go immediately to the eye of the same side, those fibres,
placed in its interior sid^, are directed obliquely towards the other nerve, without,

OP THE FORMATION OF THE SPINAL MARROW AND BRAIlSf. 53

however, any crossing of fibres being1 manifest at the point where the junction of both
nerves take place.

M. Treviranus has, in a great measure, confirmed these observations, on the male
simia avgiila. The nerves and brain were left during some months in alcohol, and af-
terwards kept some time in caustic potash to soften them. Having thus prepared
them, he submitted them to a careful dissection, when he made out, with the aid of
a microscope, that the external fibres of the upper side of each were continued from
their cerebral extremity to that in the eye, without uniting1 themselves to those of the
other side ; whilst, on the contrary, the internal and inferior fibres of one nerve went
to the other side, and united with the fibres of the opposite nerve. It was difficult to
determine whether any of the fibres actually passed from one side to the other. He
thought, however, that sume of the fibres di'd so. The internal fibres, thus interlacing
together, were evidently more numerous than the external fibres which ran to the eye
without uniting with those of the opposite nerve — Journal Complementaire, Oct. 1823.

On the Motions of the Eye.

Mr. Charles Bell has lately examined* the motions of the eye, in illustration of the
uses of the muscles of the orbit; and has shown, in the first place, that there are mo-
tions performed by this organ not hitherto noticed. Every time the eyelids descend to
cover the transparent part of the eye, the eyeball ascends, or suffers a revolving mo-
tion. If this were not the case, the surface of the eye would not be moistened, nor
freed from offensive particles. He has proved, in the next place, that during sleep the
eyeball is turned up, and the cornea lodges secure and moistened by the tears, under
cover of the upper eyelid. He considers that these motions are rapid and insensible,
and that they are provided for the safe-guard of the eye. The other motions are vo
luntary, and for the purpose of directing the eye to objects.

Mr/Bell next examined the actions of the muscles of the eyeball, and distinguished
them, as usual, into the straight and oblique muscles. It has been supposed, hitherto,
that both these classes of muscles were voluntary ; some describing the oblique as coad-
jutors of the recti muscles, and others as opponents to the recti ; but Mr. Bel! has
viewed the oblique as provided for the insensible motions of the eyeball, and the recti
for those motions wThich are directed by the will, and of which we are conscious.

Mr. B. has also proceeded to show, that, the consciousness of the action of the recti
muscles gives us the conception of the place or relation of objects ; and has endea-
voured to prove, by observation and experiment, that the actions of the straight mus-
cles are inseparably connected with the activity of the retina; that is, with the enjoy-
ment of vision : but that the moment the vision is unexercised, the eyeball is given

May, 1823,

Of the Formation of the Spinal Marrow and Brain.
Note DD.

I. Of the Formation of the Spinal Marroio. — The researches of M. Tiedemann, the
Wenzels, Doellinger, Cams, and Desmouiins, have furnished us with much interesting
information on this subject. The soft and gelatinous state of the embryo at the ear-
liest periods of its existence, the rapidity of its metamorphoses, and the difficulty of de-
monstrating, owing to its colour and consistency, that part of the nervous system, which
from the circumstance of its supplying those parts of the embryo that are first formed,
as well as from other considerations, we are led to consider as the first which assumes
an organized appearance, combine to render the exact origin of the spinal marrow diffi-
cult, if not impossible of demonstration. Reasoning from the condition of the nervous
Astern throughout the scale of the animal kingdom, from the manner in which the dif-

£4 APPENDIX.

ferent organs seem to be formed, from the organization of some monstrous foetuses,
and from other considerations on which we cannot enter at this place, we are disposed
to conclude, that the spinal marrow is itself produced from the ramifications of the
sympathetic ganglia ; that the scmilunar ganglion is the first part of the nervous sys-
tem to assume an organized state ; and that the subordinate ganglia, the spinal marrow,
and lastly the brain, come successively into existence, and gradually arrive at their full
developement.

It is not until about the third or fourth -week that a greyish-white fluid may be de-
tected in the cavities of the head and spine. From the fourth to the fifth -week the me-
dulla eblongata may be distinctly seen. It is then about twice as thick as the medulla
spinalisy which, before the developement of the limbs, is of an equal thickness through-
out its whole length, and presents a slight curvature near the commencement of the
medulla oblongata, owing to the flexion of the head upon the chest. The spinal marrow
at this time consists of two white strips of medullary matter, which offers a manifest de-
cussation at the place where it curves forwards at the margin of the inferior extremity
of the pyramids. It is not, however, the whole of the two cords of the marrow that
cross, but the middle or pyramidal fasciculi of each. The spinal marrow descends
from this point through the whole extent of the canal to the interior of the caudal pro-
longation.

At the fifth -veek these stripes or chords form a junction of their interior and ante-
rior margins, a longitudinal gutter : their external and posterior magins are then full and
prominent.

At the seventh iveek the spinal marrow is open throughout its whole length. On each
side of the fourth ventricle, a straight thin lamina is put forth, which inclines from with-
out inwards, applying itself to that of the opposite side, without, however, uniting with
it : these are the rudiments of the cerebellum, springing from the restiform bodies. The
cervical enlargement begins to appear, particularly its cephalic extremity. The for-
mation of the limbs coincides wit^h that of the corresponding enlargements of the chord.

The longitudinal raphe, formed by the aproach of the interior margins of -the two
chords constituting the marrow, is continued upwards, and separates the tubercles, that
is, the laminse which represent them : the optic thalami are devolved.

At the commencement of the third month, the marrow is still open at its superior half,
and extends to the extremity of the sacrum. The tubercula quadrigemina are volumin-
ous, hollow and separated by the median furrow : the optic thalami are full. The two
cervical and lumbar prominences are a third of a line thicker than the body of the mar-
row: Tiedemann has not observed the junctions of its exterior margins until the end
of the third month. Serres has seen it a fortnight earlier. This junction takes place
from beneath upwards.

At twelve -weeks the marrow extends only to the middle of the sacrum. The tubercula
quadrigemnia are united and form a canal ; at this period the mammillary eminences
and the corpora striata may be seen. The internal canal, which is now formed by the
junction of the margins of the marrow communicates with the fourth ventricle. Ac-
cording to M. Desmoulins, this canal results from a sinus, formed by the fold of the pia
mater as it dips into the interior of the marrow, or rather between both the cords of
which the marrow is then formed. The precise period at which this canal is com-
pletely obliterated, has not been ascertained. M. Carus conceives that the pectoral
portion of the marrow is the first to close, and that the canal is obliterated along its
whole extent, owing to the formation of the gray substance.

At the fourth month, the spinal marrow reaches only to the base of the sacrum; the
cervical eminence is larger than the lumbar. The two contiguous cords of the marrow
divide, in the medulla oblongata, each into three others much smaller. The internal
or pyramidal forms a tolerably broad surface, as in fishes and reptiles, and evidently
crosses, as was already noticed, with that of the other side about the fourth or fifth
week of the foetal life. The middle cord, or the corpus oblivare, is placed above the
former; some of its fibres ascend to the tubercula quadrigemitui, and unite with those
proceeding1 from the opposite side, in order to form the vault of the aqueduct of Syl-
vius. The external or restiform cord, proceeding from the lateral and posterior por-
tion of the marrow, forms the prominent paries of the fourth ventricle, and advances
into the cerebellum. At this period the annular protuberance is perceptible. The
interior canal of the marrow is now very narrow, and still communicates with the fourth
ventricle. It is not until towards the end of the fourth month that the lumbar and sa-
cral nerves become elongated, and form what has been improperly called the caiirla
equina, which at first does not exist. The pia mater which penetrates by the posterior
median furrow, is observable in the centre of the marrow.

01? THE CEREBRO-S FINAL SYSTEM. £5

At thejifth mnnth, the pyramidal eminences are evident : there still exists a commu-
nication between the fourth ventricle and the canal of the marrow. The two swellings
of the cord are well marked. The annular protuberance becomes more distinct, and
the corpora siriata are large. The increased thickness of the tubercles has narrowed
considerably the cavity which they formed by their approach. The marrow extends at
this period no farther than the margin of the fifth lumbar vertebra.

The human embryo possesses a caudal prolongation until the fourth month of uterine
life. At this period it disappears, and its disappearance coincides with the ascension of
the spinal marrow in the vertebral canal. If the ascension of the marrow is arrested,
the human fetus is born with a tail, as has been observed in several cases. The cir-
cumstance of the spinal marrow descending1 lower in the vertebral canal the younger the
foetus, has attracted the particular notice of those physiologists, to whose researches we
are indebted for our knowledge of the subject under consideration. M. Tiedemann,
who offers the most rational explanation of this phenomenon, supposes that the marrow
descends not so far in the canal of the full-grown fetus, as in that of the early embryo,
because the vertebral column grows more rapidly in length, than the nervous Cord
tvhich it is destined to protect.

To wards the end of the sixth month, the corpora vlivaria form a well-marked lateral
projection. At this epoch may be seen the internal and middle cords, forming the pe-
duncles of the brain, plunging into the optic thalami which they formed by their en-
largement. The fibres composing them may be perceived on scraping away a thick
pulpy layer from their interior and superior aspect. A few fibrous portions detach
themselves from their internal side, and proceed outwards to the mammillary eminence.
All the other fibres continue to advance from behind forwards, and from within out-
wards, beneath -the corpora striata, and proceed, in a diverging form, to the cerebral
lobes. A few fibres may be seen entering them. In the course of the sixth month
the transverse furrow separating the eminentia quadrig'endna begins to appear, or rather,
each of these prominences becomes more developed.

At the seventh month, the length of the marrow is nearly the same. The transverse
fibres which compose the annular protuberance are now distinct, and they may be seen
interlacing with those of the pyramids. This part results from the following disposi-
tion ; the fibres of one lateral hemisphere of the cerebellum are continued beneath the
spinal marrow with the fibres of the opposite hemisphere, by layers which alternate
with the planes of fibres proceeding obliquely from the pyramids to the optic thalami.

At the eighth month the marrow reaches only to the fourth lumbar vertebra, and at
the ninth month it is at the margin of the third. The interior canal of the marrow still
exists, and remains until from six months to a year after birth. It is at the last months of
gestation that the disposition of the medullary fibres of the marrow may be most dis-
clistinctly traced, and the mode of formation of the mesocephalon or pans Varolii,
which is only a continuation of the marrow, becomes most evident.

All the white or medullary parts which are seen at the base of the brain, manifestly
arise from the superior part of the spinal marrow. (OLLIVIEH. sur'le Beveloppemeitf d&
la Moelle Opiniere.)

II. Of the Formatioji of the Brain.— -The. interesting results of Dr. Tiedemann's re-
searches on this subject may be reduced to the following heads :

" 1. In the commencement of pregnancy, especially about the second month, the
earliest period at which the brain can be rendered perceptible by the action of alcohol,
this organ is very small in proportion to the spinal marrow. In fact, it results from the
prolongation upward and forward, of the two principal cords, the olivary and pyrami-
dal. All its superior part is open, or, more properly speaking, forms a broad gutter,
which at once comprehends the third ventricle, the aqueductus sylvii, the fourth ven-
tricle, and calamus scriptorius. This gutter is interruptedly continuous with the canal,
which traverses the whole length of the marrow.

'* 2. The cerebellum evidently originates from the spinal marrow ; from the lateral
parts of which arises, on each side, a small flattened cord. These two, at first so dis-
tinct and separate that they may be readily parted without laceration, afterwards unite
so as to form ttie roof of the fourth ventricle. Then only the brain, viewed from above,
ceases to represent a gutter ; and the lamina: and branches of the cerebellum are formed
at a much later period.

"3. The mass which supports the tubercula quadrigemina equally shows itself in its
origin, under the form of two small thin membranes, which arise from the olivary cords

I

66 APPENDIX.

of the spinal marrow, and which, when they cease to be distinct, represent a vault co-
vering a large ventricle, whose successive contraction gives rise to the aqueductus
sylvii.

" 4. The pyramidal cords of the spinal marrow, which take a direction below up-
ward, and from bekind forward, after having produced two swellings, or ganglia, the
optic thalami, and corpora striata, each terminate by a lamina, which bent from before
backward, and from the side towards the superior and internal part, forms the com-
mencement of the hemisphere of the brain. These membranes and thin hemispheres
are so small at the second month, that they scarcely cover the corpora striata. In pro-
portion -as they increase they extend backward, and cover, at the third month, the optic
thalami ; at the fourth, the tubercula quadrigemina ; and, at the sixth or seventh, the
cerebellum. The lateral ventricles result from their inversion.

"5. The medullary fibres of the pyramidal cords, previously to the formation of the
tuber-annulare, are immediately continuous with those of the crura cerebri ; from
whence the eye may readily trace them in the optic thalami, and corpora striata, and see
them aftewards spreading and radiating in the hemispheres.

" fl. The parietes of the hemispheres gradually increase in thickness in proportion as
new strata of cerebral substance are deposited on the surface ; and convolutions- are not
decidedly seen till towards the close of pregnancy.

" All these combined facts clearly demonstrate, in the opinion of Dr. Tiedernann, that
the brain and cerebellum proceed from the spinal marrow : or that, to employ a mo-
dern expression, they are an efflorescence of it. In running through the scale of ani-
mals, ample confirmation may be found of the assertions here advanced. The structure
of the encephalon and spinal marrow becomes complicated in proportion as we ascend
from fishes to reptiles, birds and mammalia. If the contrary opinion were correct— if
the spinal marrow were derived from the brain, the cerebrum and cerebellum must ne-
cessarily be found the first formed in the foetus, which is not the case. It is equally
necessary that, in the animal scale, where it is impossible to mistake a gradation in the
figure and developement of the organs, that a complete brain should exist previously to
any trace of a spinal marrow ; but this is never observed. Comparative anatomy, on
the contrary, shows that the spinal marrow is very large in the inferior classes of ani-
mals, while the brain forms but a small and delicate prolongation of it ; and in ascend-
ing from reptiles to birds and mammalia, it is seen gradually to increase in volume and
complication, as abs6lutely takes place in the foetal encephalon*.

* Prochaska and the Wenzels conclude from their microscopic observations, that the
brain is composed of a number of small globules of a tolerably firm consistence con-
tained in a flocculent pulp. The researches of Mr. Bauer into the ultimate structure of
this organ are more precise. He considers that the brain and nerves consist of extemely
delicate fibres, formed of minute globules, connected together by a transparent gelan-
tinous fluid, or viscid mucus, which is soluble in water. These globules vary in dimen-
sions, from •j-g— Q- to -j-^Q-g- parts of an inch. " The principal difference," he states, " in
the appearance of the different parts of the brain, consists in the proportions which the
quantity of mucus and fluid bear to the quantity of globular tissue, and in some measure,,
in the size of the globules. The cortical substance of the cerebrum and cerebellum
is made up by the small globules, the gelantinous fluid and mucus being very abundant.
The medullary substance in the cerebrum and cerebellum differs from the above, in
the large globules prevailing, the mucus being more tenacious and less abundant. The
crura cerebri and cc rebelli resemble the medullary substance, only that the mucus and
fliu Is are more abundant, and in greater proportion than the globules.

The medulla oblongata, the corpora pyramydalia, and olivam, have nearly the same
structure as the medullary substance, but the mucus is very abundant. In the medul-
la spinalis, the mucus and fluid are less tenacious, but in greater quantity than in any
part of the brain.

Every part of the brain is pervaded by innumerable bloodtvessels, which are of consi-
derable size towards the centre, but branch out to an extreme degree of minuteness ;
but even then carry red blood. The arteries in the brain never anastomose, and are
accompanied by veins still smaller, which are supplied with valves.

This view of the structure of the cerebrum and cerebellum is calculated, In the opi-
nion of Sir Everard Home, to throw considerable light on the functions of the brain.
He thinks that the cortical substance is one of the most essential parts of this organ,
and considers it the. seat of memory, from having observed that that faculty is destroyed
or materially diminished by any undue pressure upon the upper anterior part of the

OF THE CERfcBKO-SPlNAL SYSTEM.

Of the Functions of the Cerebro-spinal System of Nerves.

I. General t'/ew of t fie J\"ervous System. — At a former part of these notes we divided
the nervous system into two principal orders, viz the ganglial or vital, and the cerebro-
spinal. Of the former we remarked, that the globules of which it is constituted are disse-
minated in the structure of the Zoephyta, are organized into a homogeneous ganglion,
but imperfectly developed in many of the orders of the Ecliinvdennata, and are arrang-
ed into ganglia communicating by means of intermediate cords in the JlnneUdee, Cirrhi-
pedes, &c. The homogeneous nature of the ganglions disappears as the animal is pro-
vided with separate organs, especially with those devoted to the senses : and, with the
development of separate organs, accessary or subordinate, ganglions make their appear-
anee, which latter, in the progressive rise in the scale of the animal kingdom, assume in
the anterior part of the body of the animal the character of the rudiments of an ence-
phalon. So long as there exists only simple ganglia without any spinal cord, the gan.
glion representing the rudiments of an enoephalon, surrounds the oesophagus in the
manner of a ring. This encephalic ganglion is intimately connected with the ganglial
functions, and presides over those imperfect operations of sense with which the ani-
mal is endowed, and which are those more immediately subordinate to its fttnctions of
nutrition, and to its immediate preservation,

In all animals possessing no other rudiments of the cerebro-spinal system, than an ac-
cessary ganglion disposed around the oesophagus, the manifestation of volition is by no
means distinct; their movements appear to be the result neither of reflection nor of
choice. An obscure instinct seems to be the actuating principle of those operations,
which may assume in them the nearest resemblance to those of volition.

As we rise in the scale of the animal creation, and as we perceive the relation be-
tween the exterior world and the animal, to be more extended and intimate, owing to
the extension and perfection of the organs of sense and volition, so we perceive the ce-
rebro-spinal system more perfectly organized, more fully developed, and more compli-
cated in its structure. With the formation of the spinal cord, in the class of fishes,*
the accesary encephalic ring or ganglion disappears, and the encephalon is surrounded
by a protecting case, which is continued over the cord itself.

The diversity and complication of the parts constituting the encephalon increase as

mass composed of two symmetrical hemispheres, the prototype of the cerebral hemis-
pheres of all the superior classes.

brain, as in that requiring the operation of trepan. In hydrocephalus, on the other
hand, where the fluidi s in large quantity, and there only remains the cortical part of
the brain, and pons Varolii, all the functions go on, and the memory can retain passages
of poetry. In one case, slight pressure upon the sinciput produced complete derange-
ment, and violent excesses of the passion of lust, which went off by removing, by tiie
trepan, the depressed bone.

The veins being so minute, and being supplied with valves, perform in the opinion
of this physiologist, the office of absorbents — which have never been observed in the
brain — and carry the absorbed matter into the superior longitudinal sinus, which ap-
pears more a reservoir than a vein.

The transparent mucus being not only one of the most abundant materials of which
the brain itself is composed, but also the medium by which the globules are kept to-
gether, and serving the same purpose in the nerves, Sir E. H. thinks that the commu-
nication of sensation and volition depends apon it. He concludes from all his experi-
ments a;id observations, that this fluid, as well as the principal materials of which the
body is composed, are met with in the blood.

* M. Desmoulins has lately shown that many reptiles and several fishes offer not a
trace of grey substance in their spinal cords, and that on the contrary, this part is en-
tirely composed of white substance. He has also found that the sturgeon is entirely
\vithout a cerebellum ; and that its fourth ventricle possesses a considerable extent.

He concludes that the dimensions and extreme development of the fourth ventricle
always coincides with the extreme development of the eighth pair of nerves. The cir-
cumstance of the grey substance being wanting in the spinal cord of some fishes mili-
tates against the opinion of M. OLlivier stated at a subsequent page.

68 APPENDIX.

In another part of these notes we gave a full detail of the progressive development of
the cerebro-spim-1 system of nerves in the human ftctus. It will readily appear from
what we there advanced, that a similar gradation, (from the simplest to the most com-
plicated and perfect state of the Y,-; -. vous structure,) to that which we observe in ascend-
ing the scale of the animal creation, may L-e remarked in the changes which the nervous
system undergoes in the progressive evolution of the human embryo. In the lowest
of all the animal kingdom the nervous matter is not organized in a manner distinct
from the tissue constituting the anim?l : the nervous globules are disseminated through
an amorphous and pulpy mass. As we ascend the scale we perceive this particular struc-
ture arranged in succession into ganglia ; then into ganglia and spinal marrow ; and lastly
into ganglia, a spinal marrow and a brain, — each becoming more perfect as we ascend the
scale, and the gradation from the one to the other being nearly unappreciable in the
species or genera, but sufficiently remarkable in the orders. A development of the
nervous system, in which a similar progression to this is observed, takes place in the
formation of the human fa-tus, and in that of the most perfect animals ; and a similar
type to that, in which this system exists in the lower orders, is adopted at first in the
highest, and preserved, — every successive state of organization which this system as-
sumes in its progressive development being additions to that previously adopted, whilst
in the process of formation as respects the entire animal, each intermediate series from
the lowest, which is its first state of existence in the embyro, is successively passed
through, until the foetus arrives at that specific condition and stage of organization be-
stowed on the species to which it belongs. Thus the human foetus in the progress of
its formation, as respects both its nervous system and other organs and textures, runs
through the different grades of organization from the lowest, to that of the head of which
it is itself placed, j- ( See the Note on the Development of the Fatus. )

II. Of the Functions of distinct parts of the Cerebro-Spinal Order of the J\ervous Sys-
tem— The researches of M. Flourens into the functions of the cerebro-spinal order of
nerves, have lately added greatly to our knowledge as to actions in which distinct parts
of this part of the nervous system are more particularly concerned. But before we
can give any account of the conclusions at which he has arrived, we must briefly no-
tice the meaning lie has attached to some of the terms which he employs.

The term contractibility he very properly limits to the property inherent in the mus-
cular fibre only, of undergoing brisk contractions under the application of stimuli : and.
the term sensibility, to imply the property of experiencing sensations. The word irri-

f Sir Everard Home, Merrs. GeofFroy Saint Hilaire and Blainville and Dr. Schultze,
consider that the skeleton of animals was intended more to prevent the nervous and
vascular system from being compressed or suffering any other injury, than to give form
and the power of motion to the body. The last named physiologist (Jlllgemeine En-
tyclopccdiefur Practische Jlrx'.e und Wundarzte, 1 theil, 1 band Ltip. 1 820.) concludes :

1° " That the spinal marrow and vertebral column at all times exist together, even
only the slightest vestiges of the osseous system can yet be found.

2° " That the osseous and nervous systems have between them numerous intimate
relations, both physiological and pathological.

3° " That the more the exterior hard envelopment penetrates the interior of the bo-
dy, and approaches towards the nervous system, the more also are the phenomena of
sensibility developed, and nice vtrsa.

4. " That the organs possess more or less importance according as they are more or
less protected from external influence by bones."

The blood proceeding from the mass of muscles, spine and spinal marrow, is empti-
ed into the great spinal veins, as into a reservoir ; when it passes into the veins placed
on the sides and anterior surface of the spine, and thence into the superior und inferior
cavs:.

By what power, it has been asked, is the blood which arrives in the two great spinal
veins, driven from them ? These veins may effect the propulsion of the blood which
they contain, by the vital properties with which they are endowed ; the blood may be
drawn oui of them, owing to their proximity to the cava by the dilatation of the cavities
of the heart : or by both influences combined.

OF THE CEREBRO-SPINAL SYSTEM. 69

lability^ he applies to the property of exciting sensation and motion, without evincing
or experiencing them. This application of the word is by no means judicious; it must
however, be allowed, that it i3 not easy to find a term which can convey the meaning
wished to be attached to it.

The questions proposed by Mr Flourens, and which he lias endeavoured to ascertain
by experiment are : — 1st, from what points of the nervous system artificial irritation may
jet oft' to arrive at a muscle ; 2cl, to what points of this system an impression must be
propagated to produce sensation ; 3d, from what points voluntary irritation descends,
and what parts of this system most be influenced to produce it regularly.

M. Flourens commenced with the nerves, and fully confirmed the views usually enter-
tained respecting their functions. He has shown, in a satisfactory manner, «' that, hi
order to effect contraction, a free and continued communication is requisite between the
nerve and i. I that to produce sensation, a similar communication with the

brain is equally necessary. '5-nce 1;?. concludes, that neither contraction nor sensation
belong to the nerve ; that these two effect ,'U they may take place in-

dependently of each other ; and that these propositions hold good, at whatever pia't,
and in whatever branch of a nerve the communication is interrupted.

** Employing the sante method with regard to the spinal marrow, he arrived at similar
conclusions. When it is irritated in any given point, contractions are excited in all the
muscles which derive their nerves from below this point, if the communication remains
free but not if the communication be interrupted. Exactly the reverse obtains with
regard to sensation ; and, as in the nerves, the government of the will requires th«
same freedom of communication as sensation, the muscles beneath the intercepted part
no longer obey the animal, and he has no feeling in them : in fine, if the spinal mar-
row be intercepted at two points, the muscles which receive their nerves from this in-
terval experience contractions alone ; but the animal does not command them, nor receive
from them any sensation." M. F. farther inferred, from his experiment respecting the
functions of the spinal marrow, that sensation and contraction belong no more to it
than to the nerves.

He next directed his researches to the brain, in order to ascertain the point whence
irritation departed, and point where the sensation arrives, and to determine their
respective co-operation in acts of volition. Advancing from the medulla oblongata
towards the hemispheres, Mr. Flourens first examined how far it was possible to go, and
still produce sufficient irritation on the muscular system, when he arrived at a point
where these irritations disappeared : " then taking the brain at the opposite part, he
irritated it at points deeper and deeper, as long as he did not act upon the muscles ; and
when he did begin to act upon them, he found himself at the same point where the ac-
tion had ceased in ascending. This part is -also that where the sensation of irritation ap-
plied to the nervous system likewise ceases : above this, punctures and wounds do not
excite pain. Thus M. Flourens pricked the hemispheres without producing contraction
of the muscles, nor the appearance of pain in the animal ; he removed them in successive
slices ; he did the same with regard to the cerebellum ; he removed at once the hemis-
pheres and cerebellum. The animal remained passive. The corpora striata and the
optic thalanil were attacked, and removed without any other effect : the iris was not con-
tracted, nor even paralysed. But when he pricked the t-ubercula quadrigemina, trem-
bling and convulsions began, and these increased in proportion as he penetrated into
the medulla oblongata. Pricking the tubercles, as well as the optic nerve, produced
quick and continued contraction of the iris. These experiments agree with those of
Lorry, published in third volumeof the ' Mgmoires des Savans etnmgers.' < Neither the
irritation of the brain, nor of the corpus callosum itself produce convulsions : it may even
be removed with impunity. The only part among those contained in the brain which
has appeared uniformly and universally capable of exciting convulsions, is the medulla
oblongata: it is this part which produces them to the exclusion of every other.' They
contradict the experiments of Haller and Zinn with regard to the cerebellum ; but,
from what M. Flourens has sc>en and pointed out, it appears that these physiologists had
touched the medulla without being aware of it. He concludes that the medulla oblon-
gata and the tubercles are (in his language) irritable ; which means that they are con-
ductors of irritation, like the spinal marrow and nerves, but that neither the cerebrum nor
cerebellum possess this property. The author hence concludes, likewise, that these
tubercles form the continuation and superior termination of the spinal cord and medulla
oblongata; and this opinion is in conformity with their situation and anatomical con-
nexions.

Wounds of the brain and cerebellum do not excite pain any more than convulsions.
Hence M. Flourens infers that to them, the impression received by sensible organs
must be conveyed, in order that the animal may experience a sensation. He appears

70 APPENDIX.

fto have established this proposition in a satisfactory manner, with regard to the senses of
sight and hearing1; tor when both lobes of the cerebrum are removed, th« animal becomes
both blind and deaf. « Instead of saying, with M. Flourens, that the cerebral lobes
are the only organs of sensation, we should restrict ourselves to ascertain facts, and con-
tent ourselves with saying that these lobes are the sole receptacle where the senses of
sight and hearing can be perfected, and become perceptible to the animal. If we
wished to add to this, we should say that they are likewise those where all the sensa-
tions take a distinct form, and leave durable traces on the memory, — that they serve, in
a word, as the seat of memory ; a property, by means of which they furnish the animal
materials for judgment. This conclusion, thus reduced to proper terms, becomes the
more probable, in that, besides the veri-similitude which it receives from the structure
of these lobes, and their connexion with the rest of the system, comparative anatomy
offers another confirmation in the constant relation of the volume of these lobes with
the degree of intelligence of the anmal."

M. Flourens next examined the effects which follow the extirpation of the tubercnla
quadrigemina. " The removal of one of them, after a convulsive movement, which
soon ceases, produces, a permanent result, blindness of the opposite eye and involun-
tary staggering ; that of both tubercles renders the blindness complete, and the stag-
gering more, violent and long-continued. The animal, however, retains all its faculties
und the iris continues contractile. Tho deep extirpation of the tubercle, or the sec-
tion of the optic nerve only, paralyses the iris : from which the author infers, that
the the removal of the tubercle only acts as the division of the nerve would do ; that
this tubercle is only a conductor uith regard to vision ; and that the cerebral lobe alone
Is the seat of the sensation, the point where it is consummated, and passes into per-
ception."

M. F. next investigated the functions of the cerebellum,, and found that, during the
removal of the first layers, " there appeared only a slight weakness and want of har-
mony among the movements. At the middle layers, a disturbance nearly general was
manifested. The animal, in continuing to see and hear, only executed quick and ir-
regular movements : the faculty of flying, walking, and keeping itself standing, were
lost by degrees. When the bra'in was cut off, this faculty of performing regulated mo-
tion had entirely disappeared. Placed upon the back, he did not rise ; but continued
to see the blow which menaced him ; he heard sounds, and endeavoured to shun the
danger which was threatened : in a word, feeling and volition were retained, but the
power over the muscles was lost; scarcely could he support himself with the assistance
of the \yings and tail. In depriving the a'nimal of the bruin, it was thrown into a state
resembling sleep : in removing the cerebellum, it was brought to a state resembling
intoxication."

The reporters to the Institute on the inquiries of M. Flourens, have drawn the fol-
lowing conclusions " from a rigorous examination of the facts which he has establish-
ed : — the integrity of the cerebral lobes is necessary to the exercise of sight and hear-
ing : when they are removed, the will no longer manifests itself by voluntary acts.
However, when the animal is immediately excited, he performs regular movements, as
if endeavouring to avoid pain or inconvenience ; but these movements do not effect his
purpose, most probably because the memory, which has been removed along with the
lobes which constituted its seat, no longer affords grounds or elements of judgment :
Ihese movements have no consistency, for the same reason, that the impulse which
caused them neither leaves any remembrance nor permanent volition. The in-
tegrity of the cerebellum is necessary to the regularity of locomotion : let the brain
remain, the animal will see, hear, and have evident and powerful volition ; but, if the
cerebellum be removed, he will never find the balance necessary to locomotion. As
to the rest, irritability remains in parts without the brain or cerebellum being neces-
sary. Every irritation of a nerve brings it into play, in muscles to which it is distribut-
ed : every irritation of the spinal marrow excites ft in all members beneath the point
of its application. It is quite at the top of the medulla obhwgata, at the point where the
tubercula quadrigemina join it, that this faculty of receiving and propagating irrita-
taion on the one hand, and pain on the other, ceases. It is this point at which sensa-
tion must arrive in order to be perceived ; it is from hence that the mandates of the
will must emanate. Thus, the continuity of the nervous organ from this point to the
different parts of the body is requisite for voluntary motion, and for the perception of
impressions whether external or internal."

Thus, then, the property of nervous irritability or of receiving and conducting sensa-
tion and irritation is limited to the nerves, spinal cord, medulla oblongata, and corpora
quadrigemina, " the integrity of the optic thalami is not essential to the contractility
of the iris ; the sensations of light and of sound reside in th~ cere-bra! lobes, and therv

OF THK CEREBRO-SP1NAL SYSTEM, 7|

also all other sensations acquire distinctness and durability; the spinal cord combines
the muscular, contractions so as to produce motion in the joints ; and the cerebellum
regulates these movements, and unites them so as to constitute the actions of standing-
and locomotion :— such are the discoveries of M. Flourens*."

III. jQf the distinct Functions of the anterior and posterior Columns of the Spinal Mar-
row. It is certain that the spinal marrow sends oft' nerves engaged in the performance
of two distinct functions, viz. that of feeling- and that of motion. From what part —
we are led to ask — of this organ, do the nerves allotted to each of these functions pro-
ceed ? It is well known that the spinal marrow is formed of two substances— a white
substance, which is exterior, and a gray substance, occupying the interior of the cord,
The continuity of the fibres composing the roots of the spinal nerves with the latter,
as established by Keuifel and Ollivier, naturally leads us to suppose that it is particu-
larly concerned in the production of these functions. It may be also observed, that

* Experiments, similar to those of M. Flourens were instituted, in 1805, by profes-
sor Rolando, of Turin, from which he deduced inferences in some respects the same
as those at which M. Flourens has arrived. The experiments of the latter physiologist
were, however, more varied, were, apparently, more carefully performed, and there-
fore were more conclusive, than those of his predecessor. They were repeated, more-
over, before a commission of the institute of France, composed of some of the most
eminent of that body, who approved of the conclusions which are given above. The
following are the inferences which M. Flourens considers that his experiments justify.

1. " No movement proceeds immediately from the will. The will is the exciting and
determining cause of certain movements ; but it is never the efficient or effective cause
of any.

2. " It has been shown that the immediate cause of muscular contraction, particu-
larly resides in the spinal marrow and nerves, and that the regulating cause of these
contractions is placed in the cerebellum.

3. " There are, therefore, three phenomena essentially distinct in a movement pro-
ceeding from volition : 1, the volition of movement, a volition which seems to reside in
the cerebral hemispheres : 2, the appropriate regulation of the different muscular con-
tractions productive of motion, which reside in the cerebellum : and 3, the excitation
of these contractions, which has its efficient seat in the spinal marrow and its nerves.

4. "As these three phenomena, essentially distinct, reside in three organs also dis-
tinct, the possibility of abolishing any one of them, and leaving the others uninjured,
seems apparent ; thus the will may be destroyed, and the regulation of contraction it-
self will remain : or both volition and the regulating cause of contraction may be
abolished, and contraction will alone be produced, &c.

5. " There exists, therefore, in the nervous system, (cerebro-spinal system,) three
properties essentially different : one, the exciter of motion ; the other the regulator /
and the third, the -wilier and perceiver.

6. "The spinal marrow, the medulla oblongata, the tubercula quadrigemina, alone
possess the property of directly exciting muscular contraction ; the cerebral lobes and
cerebellum do not possess it.

7. " There are two ways of destroying vision without g'oing beyond the cerebral
mass : one by the removal of the tubercula quadrigemina — producing loss of the sense
of sight, the other, by the removal of the cerebral lobes, — causing the loss of the sen-
sation of sight.

8. " There is, therefore, in the cerebral mass, distinct organs for the senses, for.the
sensations -, for the movements.

9. *' Not only all the sensations, all the perceptions, all the volitions, all the intellec-
tual and sensitive faculties reside exclusively in the cerebral lobes, but all these facul-
ties occupy jointly the same seat in these organs ; for if one of them disappear, all
disappear ; and if one return, all return. The power of feeling, willing, and per-
ceiving constitute therefore but one faculty, residing but in one organ.

10. " The cerebral lobes, the cerebellum, the tubercula quadrigemina, may lose a
considerable, bat limited, portion of their substance, without losing the exercise of
their functions ; and they may re-acquire them after being totally deprived of them.

11. " The spinal marrow and the medulla oblongata, are the only parts which directly
affect the same side of the body, with that in which they are themselves aifected.
The tubercula quadrigemina, the cerebral lobes, and the cerebellum alone produce
their effects upon the opposite side to that in which they are influenced ; — the former
act in a direct course, the latter in a cross direction."

72 APPENDIX.

the fibres of the anterior roots are much smaller than those of the posteriory—a ch*-»
cumstance which, when viewed in connexion with what has been advanced on the sub*
ject by Mr. Charles Bell* and M. Magendie shows that each set of fibres (posterior and
anterior) is more immediately allotted to the performance of a distinct function, — that
the posterior roots are devoted to the sensibility 'of the parts which these nerves sup-
ply, and the anterior to the muscular contractions. But it appears, from the experi-
ments of M. Magendie, .that one of these functions does not exclusively belong1 to one
order of these roots ; for, when the posterior roots, or those which more particularly
belong1 to sensibility", are irritated, contractions are occasioned in the muscles to which
their nerves are distributed, although the contractions are much more strong and much
more complete when the irritation is directly applied to the anterior roots of the nerves.
Slight appearances of sensibility are also occasioned when irritation is made on the an-
terior roots. It must therefore be concluded, that sensibility, although chiefly, is not
exclusively, in the posterior roots, nor motion in the anterior.

This defect of complete isolation of these two functions may arise, as M. Ollivier
supposes, from the gray matter of each lateral half of the marrow, which seems to be
concerned in their production, being entirely confounded at their central points of
contact ; and from the intimate union which takes place between both the roots, be-
low the spinal enlargement (intervertebral ganglions) and which must contribute still
farther to combine these functions so as to prevent their perfect separation.

It should be recollected that the functions ought not to be attributed to the roots of
the nerves themselves. M. Magendie found, that when these nerves were divided close
to the marrow, and irritation then made on their roots, no sensible effect followed :
whereas, while their connexion with the marrow was preserved, the slightest irritation
was productive of effect ; and the nearer that it was made to the spinal cord, the more
intense was the influence occasioned by it. Hence it follows that the gray substance
of the cord, whence arise the roots of the spinal nerves, is much more intimately con-
cerned in the production of the operations in question than the roots of the nerves
themselves ; but this substance itself seems to depend more upon the differts parts
composing the encephalic mass, for whatever influence it may exert in the production
of the phenomena under consideration, than M. Ollivier appears to allow. He attri-
butes them both almost exclusively to the gray substance of the centre of the cord,
which he considers to be voluminous in proportion as these faculties are developed.
This part of the cord, although altogether necessary to, and instrumental in, their pro-
duction, can only be viewed as one of three distinct classes of structure, each of which,
as M. Flourens has stated, performs distinct actions, which by their combination, con-
stitute but an individual function, that could not result from any one or two only of the
actions composing1 it, but is the consequence of a more or less perfect co-operation of
the whole*.

* Mr. Bell's attention was attracted by " the difference in the distribution of the
nerves of the head from those of the body, and the fact that all the spinal nerves arise
by double roots. Observing that this form of origin was the same in all animals pos-
sessing a spinal cord, and considering that the anterior column of the spinal marrow
was continuous with the crura of the cerebrum, and the posterior with the crura of
the cerebellum, — he conceived that by experiments on the roots of these nerves,
he might discover the functions of the the two columns, and, perhaps, through
them, arrive at a more accurate knowledg of the relations and individual uses of
the cerebrum and cerebellum." Previously, however, to these experiments, Mr.
Bell entertained the opinion that the anterior column of the spinal cord was dif-
ferent in function from the posterior; and that, through the former, the simple
voluntary power of moving particular parts was conveyed. He deduced this from
observing, that the two nerves, which are generally supposed to be purely motors,
arise from the anterior fasciculus. The experiments which these opinions suggested,
although they were not conclusive, yet encouraged the view he had taken, and gave
results in some degree similar to those which Magendie subsequently obtained from
his experiments. To Mr. Bell, therefore, the honour of having originated these views
clearly belongs.

* Of the distinct functions of the cerebellum, numerous opinions have been lately en-
tertained. Dr. Gall considers it to be the seat of physical love. Mr. Rolando, who
adopts the opinion of a nervous fluid, which he regards as analogous to the galvanic
fluid, places the source and seat of the principle of muscular contraction in the cere-
bellum, which, owing to the disposition of its laminated convolutions, he considers to

OF THE RESPIRATORY ORDER OF NERVES. 73

IV. Of the Respiratory Order of Ncnvs. — All animals that possess a perfect cerebrn-
•spinal system have an intermediate order of nerves which connect the vegetative func-
tions of the ganglial system with the functions of the encephalon. This order of nerves
has lately been very satisfactorily examined into, both as respects their distribution and
functions by Mr. Charles Bell.

On investigating- the minute structure of the nerves whi«h, both in man and in the
lower animals, arise from the spinal marrow by double roots, and those which proceed
from the medulla oblongata, by single origins, to the organs of respiration and those
parts of the face and trunk which evince an intimate relation with this important func-
tion, Mr. Bell perceived their texture and mode of distribution were very different.
This circumstance led him to consider that two distinct orders of nerves must exist in-
dependently of the sympathetic, the one simple and uniform, the other irregular and
complex in proportion to the complexity of the organization. The former he has called
original or symmetrical, the latter supcradded or irregular. In the superadded class of
nerves, which are chiefly devoted to the function of respiration, Mr. Bell arranges, 1st,
the par vagum ; 2d, the portio dura ; 3d, the spinal accessory ; 4th, the phrenic ; 5th,
the external respiratory nerves, &c. " The nerves,'* this Physiologist states, " on which
the associated actions of respiration depend, and which have been proved to belong to
this system, by direct experiment, and the induction from anatomy, arise very nearly
together. Their origins are not in a bundle, or fasciculus, but in a line or series, and
from a distinct column of the spinal marrow. Behind the corpus olivare, and anterior to
that process which descends from the cerebellum, the corpus retiforme, a convex slip of
medullary matter, may be observed ; and this convexity, or fasciculus, or virga, may be
traced down the spinal marrow, betwixt the sulci, which give rise to the anterior and
posterior roots of the spinal nerves. This portion of medullary matter is narrow above
where the pans varoUi overhangs it. It expands as it descends ; opposite to the lower
part of the corpus oli-vare it has reached its utmost convexity, after which it contracts a
iittle, and is continued down the lateral parts of the spinal marrow."

From this tract of medullary matter on the side of the medulla oblongata, arise in
succession from above downwards the portio dura, the glosso-pharyngeus, the par vagum t
the nervus accessorius, the phrenic, and the external resfriratory. These superadded
nerves are comparatively but little sensible ; they do not arise by double roots, as the
symmetrical do : and they have no ganglia on their origins, and while the other volun-
tary nerves have large, free, and round filaments, they have a close, loose texture, re-
sembling a minute plexus. " These are the nerves which give the appearance of con-
iusion to the dissection, because they cross the others, and go to parts already plenti-
i'ully supplied from the symmetrical system."

From these anatomical investigations, and from experiments made in order to ascer-
tain the exact functions of this order of nerves, Mr. C. Bell and Mr. Shaw have drawn
some important inferences ; — 1st, They consider that the portio dura of the seventh
pair " produces all those motions of the nostrils, lips, or face generally, which accord
•with the motions of the chest in respiration. When cut, the face is deprived of its con-
sent with the lungs, and all expression of emotion. 2d, The par vagum associates the
larynx, the lungs, the heart, and the stomach with the muscular apparatus of respira-
tion. 3d. The spinal accessory controls and directs the operations of the muscles of
the neck and shoulder, in the offices of respiration. 4th, The phrenic nerve has its
functions sufficiently characterized in the name of internal respiratory, which Mr. Bell
has assigned it. 5th, The glossopharyngeal nerve, &c. ; and, 6th, the external respira-
tory nerve, perform the functions which those parts, to which they are distributed,
have in connexion with the operations of respiration.

act in the manner of a voltaic pile, and to transmit, under the direction of the brain,
and through the channel of the spinal cord and nerves, the moving principle to the
muscles. Mr. Flourens, as we have shown, views this organ as the regulator and ba-
lancer of the muscular contractions. M. Magendie regards it as requisite to the pro-
iluction of motion forwards : and Mr. C. Bell, Messrs. Fodera, Foville, and Pin el- Grand -
champ are of opinion, that it is the seat of sensibility.

K

APPENDIX.

Of the Faculties of the Mind, as evinced through the instrumentality of a perfect

Nervous System.

Note EE.

This very extensive subject can only receive a very cursory notice from us at this
place. We shall merely offer an arrangement of the powers of the mind, commencing-
with its lowest manifestations, or those most extensively disseminated throughout the
animal kingdom, and proceeding to the highest or most perfect faculties.

CLASS I. INSTINCTIVE POWERS. — (Strong and immediate incentives to Action.)
ORDJER I. Instinctive Powers -which tend to preserve the Individual.

1, The appetite for food and drink. 2. The desire of pre.
serving the animal warmth. 3, The desire of repose.
4, Desire of place.
ORDER II. Instinctive Powers -which tend to perpetuate the species.

1, The appetite for procreation. 2, Parental and filial af-
fection. 3, Desire of society. 4, Social affection, giv-
ing rise to mutual support. * 5, Sympathy.

CLASS II. INTELLECTUAL POWERS.

ORDER I. Powers of consciousness, or the simpler Manifestations of Mind.

1, Perception. 2, Attention. 3, Memory. 4, Conception,
OIIBER II. Powers of Intellection, or the more Active Powers of Mind.

1, Association of Ideas. 2, Abstraction. 3, Imagination.

4, Judgment or Reasoning.
OBDEB III. Ideas of Reflection, springing from the Exercise of the former

Orders of Powers. (Rational incentives to Action. )
1, Personality. 2, Time. 3, Power. 4, Truth, Causa*
tion. 5, Existence of a Deity. 6, Duty, Moral and
Religious obligations, Rectitude, Merit and Demerit, &c.

It will be perceived that the third order of ideas, into which we have arranged here
the intellectual powers, are chiefly derived from reflection, or from the mind itself. — Se?
on this subject the writings of Duff aid Steward ; of Doctor Brown ; Dr. Barclay, on Life
and Organization ,- Dr. Pritchard on the Nervous System ,- and the London Medical Re*.
positorii, volumes xvii. and xviii.

Of Dreaming. — Mr. A. Carmichael has lately adopted and illustrated the theory ot
dreaming proposed by Dr. Spurzheim, that dreams are caused by certain isolated por-
tions or organs of the brain continuing awake, while the remainder of it is in a temporary
paralysis from sleep. " According to this view the particular dream will be fashioned
by the part or parts which are not under the dominion of sleep ; and the irrationality of
our sleeping thoughts is accounted for by one or more parts or organs, thus acting with-
out co-operation or correction from the other parts of the encephalon."

Mr. C. enumerates no less than seven different states of sleeping and waking '.— When
the entire brain and nervous system are buried in sleep, then there is a total exemption
from dreaming. 2, When some of the mental organs are awake, and all the senses are
asleep ; then dreams occur, and seem to be realities. 3, When the above condition
exists, and the nerves of voluntary motion are also in a state of wakefulness ; then may
occur the rare phenomenon of somnambulism. 4, When one of the senses is awake,
with some of the mental organs ; then we may be conscious, during our dream, of its illu-
sory nature. 5, When some of the mental organs are asleep, and two or more senses awake ;
then we can attend to external impressions, and notice the gradual departure of our
slumbers. 6, When we are totally awake, and in full possession of our faculties and
powers. 7, When, under these circumstances, we are so occupied with mental opera-
tions, as not to attend to the impressions of external objects / and then our re very deludes
us like a dream.

OF THE MUSCULAR STRUCTURE. 75

Of the Formation and development of the Muscular Structure, and of the
Source of Irritability.

Note F.F.

In the very lowest orders of animals a muscular structure does not exist in a distinct
state. Their partial movements are performed by means of the cellular tissue of wliich
they are composed. In the lowest of the series possessing- a muscular texture, it moves
only the integuments to which it is attachedj and of which it even forms a part. In all
animals possessed of a heart, the muscular tissues constitues an important part. In all
the vertebrated animals a small number only of the muscles are attached to the mucous
surfaces, to the skin and its appendages ; whilst the greatest proportion is connected
with the skeleton for the purposes of progression.

According to the researches of Dr. Isenflamm, of Dorpat, into the progressive de-
velopment of the muscular structure in the human foetus, this tissue is formed from the
mucous and gelatinous fluid of which the embryo is at first composed;

From this mucous fluid the involutary muscles are at first developed, and afterwards
the voluntary. During the first three months the voluntary muscles present the ap-
pearance of viscous layers, with a slight yellowish tint. At the end of the third month
the tendons make their appearance. During the fourth and fifth months the muscles
become redder, more fibrous, and more easily to be distinguished from their tendons.
In the sixth month, although very soft, they are still more perfect. At the full term
of utero-gestation the muscles are formed, but they are pale, yet vascular ; they are
soft, and their bulk much greater in proportion to the tendinous and aponeurotic sub-
stances than in the adult.

As age advances, the voluntary muscles become redder and more fuUy developed,
and towards the decline of life, more rigid, less capable of quick and extensive contrac-
tion, and comparatively of less bulk than their aponeurotic and tendinous connexions.

The microscopic observations of M. Bauer, Sir Everard Home, Messrs. Prevost, Du-
mas, and Beclard, seem to prove that the ultimate muscular fibre is composed of cor-
puscles (arranged like a string of beads) in every respect similar to those in the cen-
tre of the red globules of the blood. However, to obtain a correct idea of the ultimate
conformation of the muscular fibre, researches ought to be made with this view on the
raw and unprepared muscle : for the action of heat, of alcohol and acids, evidently
produces changes in the fibre, and coagulates the albumen, which enters into its com-
position.

The voluntary nerves dip into the texture of the voluntary muscles at different points,
and divide into numerous minute fibrils, which abruptly escape demonstration. This
sudden manner of disappearing is owing to the extreme fibrils having become sol'.
and diaphanous, and deprived of their proper envelopes, so that their medullary sub-
stance is diffused, as it were, into the mucous tissue, connecting the muscular fibres.

The cerebro-spinal nerves, although they are numerous and large in the voluntary
muscles, disappear in the manner just pointed out, long before their divisions be-
come sufficiently numerous to be distributed to each muscular fibre. This being the
case, how can the action of these nerves on all the fibres be explained ? They cannot
be the direct cause of the muscular contraction, but must act in producing it through
the medium of another and a more general conformation* What this formation appear.!
to us to be, we will now endeavour briefly to show.

It has been stated that all the involuntary muscles are supplied with the ganglu-.l o:
soft nerves only ; — that they surround the arteries throughout their ramifications, an '
consequently are thus present in the voluntary muscles and in all vascular parts ; — tl:a
the voluntary nerves themselves, whether we trace the process of their formation in the
human embryo, or observe them in the lower orders of animals, seem to originate from
the ganglial, the cerebro-spinal masses being the perfectien of the nervous conforma-
tion, and the last part of it which becomes completely developed, — and that the cere-
bro-spinal nerves are destined to the performance of functions distinct from those to
which the other and more generally diffused class is alloted. As irritability is present
in parts which do not receive voluntary nerves, and in animals which do not possess

this part of the nervous sytem, this property cannot be attributed to it. To wha't other
species of organization can we refer this property ? We find it, in the r

the more perfect an!-

70 APPENDIX.

mals, chiefly displayed by the muscular structure. Is it from this circumstance, an at'
tribute of muscular parts, and the pure result of their confirmation ? One class of physio^
legists answer this question in the affirmative. But irritability has been displayed by
the lowest orders of the animal creation, wherein a muscular structure could not be de-
tected, even in the parts themselves which furnished the phenomenon, therefore, al-
though a property of the muscular fibre it is neither altogether restricted to it, nor is it
strictly the result of the organization of the fibre itself. We must, consequently, refer
this property to a conformation still more general than the muscular tissue, both as re-
spects the whole scale of the animal creation and the organization of individual spe-
cies; allowing at the same time, that a particular structure is requisite to the full and:
perfect development of this property, but that this structure depends upon a different
source from itself for the property which it displays.

Having arrived at the conclusion that irritability, although a property of muscular
parts, is not the result of muscular organization, but is derived from a" different, and
more general system, supplying the muscular structure as well as other structures, we
must next inquire what this system is. It has been already inferred, from various con-
siderations, that the ganglial class of nerves is distributed in different proportions, to
the various textures and organs of the body ; that these nerves are similarly distributed
throughout all the individuals composing the animal kingdom ; that in some of its or-
ders they constitute the only nervous system which the animal possesses : it has also been
demonstrated that this class of nerves, in a more or less perfect state of organization, is
present wherever irritability is manifested ; that these nerves are the most generally
diffused of any the animal tissues ; that no other structure exists but this which can be
shown to be present in every species of irritable parts, in all orders of animals ; and,
consequently, that to no other source but this cun the property of irritability be as-
signed.

Having inferred that the muscular fibre is only the instrument of contraction, in its
more perfect condition, — that it performs this function, in consequence of a certain con-
formation, und owing to that conformation being endowed by means of another still
more generally diffused than itself, — and that this property is derived from the ganglial
or soft nerves which proceeds either directly or as an envelope to the arteries, to all the
tissues of the body — we are led farther to infer that the cerebro-spinal nerves are dis-
tributed to muscular parts for specific purposes, but that these parts do not derive their
innate properties from these latter nerves — these nerves merely excite them, or rather
are conductors of a stimulus acting on properties which proceed from a different source.
We have contended that these properties are not innate, or the consequence of the
conformation of the muscular fibre itself; but are derived from a confirmation still more
general, which surrounds^ or is otherwise connected with, the muscular fibrils, and
that this more general conformation- is the ramifications of the ganglial class of nerves.
Conceiving, therefore, that these nerves in their state of ultimate distribution and dis-
semination in the texture of the muscle, whether in the form of unarranged globules,
or of minute and variously arranged fibrils resulting from the regular distribution of
these globules, are the chief source of the property evinced by muscular parts of every
denomination, we further conclude that the voluntary or cerebro-spinal nerves do not
produce their specific effects on the muscular fibres, 'owing to a nervous fibril being
ramified to each muscular fibril, for this does not take place ; nor. do these effects
proceed from the direct influence ef these nerves upon the muscular fibril, for the
muscular fibre derives its property or faculty of contraction from a source different from
itself, and from the voluntary nerves which occasionally excite its contractions ; but
that these nerves seem to act directly upon the ultimate distribution of the ganglial
nerves of the muscle, which latter nerves bestow on it the faculty of, or the disposition
to active contraction, on the application of a stimulus, which faculty all muscular parts
possess — the former class of nerves conveying to some of these parts only the natural
stimulus which induces contraction, or which excites the active exertion of this faculty
bestowed on these parts from a different source, namely, from the glangial system. The
mode of termination which the voluntary nerves observe in muscular parts, also favours
the opinion which we have now given. These nerves terminate, as we have already
noticed, in such a manner as kads us to inter, that they become, in a manner gradually
indentified or amalgamated, in the textures which they supply, with the ultimate distri-
butions of the ganglial nerves : and the history of the embryo, and the progressive ner-
vous development of the lower animals, would dispose us to believe that the voluntary
nerves originate in the textures to which they are ramified, from the ganglial system,
and that the larger branches of these nerves, the spinal marrow, and encephalon are
succc '^s: \v j Y formed.

oF GALVANIC ELECTRICITY 77

Of Galvanic Electricity.
Note GG.

The phenomena of electricity have been long- known to philosophers : but science
has been chiefly indebted, in our own times, to the researches oi Davy, Wollaston,
IJiot, Coulomb, Poisson, Oersted, and Becquerel, for a knowledge of the laws by which it
is characterized. The observations and experiments of these successful inquirers ap-
pear fully to warrant the conclusion, that this very active agent of nature results from
two distinct fluids universally diffused through every species of matter. During their
circulation, in their electro-motive capacity, through the corpuscles of matter forming
the crust of this planet, they accumulate in their free and uncombined state upon its
external surface, in consequence of the imperfectly conducting property of the enve-
loping- atmosphere.

The electricities " are thus confined on the superficies of the globe, and indeed of
all bodies placed on its exterior, not merely be the non-conducting faculty of the air,

and

ae'rial particles rendered fewer in number, and in other favourable circumstances of the
atmosphere, as in its humid state, the electric power emanates with rapidity from the
the electrized ball.

Such is the mode of existence of this fluid upon the surface of the earth. But there
also exists a continual condensation of the electrical agencies in the substance of the
different matters composing the crust of this planet ; and the galvanic, chemical, and
other phenomena, clearly show that although such condension of the electricities takes
place under particular circumstances of matter yet, a continuous circulation of it is also
evident under other relations. This, indeed, is observed to occur during every manifes-
tation of the galvanic influence.

Such then being the case, and as it is now generally believed that the circulation of
the electricities through the atoms of matter, or the electro-motive state, as it has with
propriety been called, gives rise to the phenomena of galvanism,* which, within these
few years, has lead to the most splendid discoveries in the physical world, is it not rea-
sonable to suppose that similar operations to those with which galvanic experiments
make us acquainted, are continually taking place in the elements of nature ? As it has
been shown that every species of matter possesses a certain proportion of the electri-
cities, may it not be allowed that under circumstances similar to those with which ex-
periment and observation make us acquainted, a continuous current of the different
electricities are produced, the rapidity and sensible effects of which vary according to
the accidental disposition and situation of the different material bodies, and their natu-
ral states of electricity. This opinion is calculated to account for many of the changes
which are continually taking place on the face of our globe, and although many may
not feel inclined to consider these fluids as the chief agents, no one can deny them a
share in producing the effects which are so frequently observed upon its surface.

The laws of electricity, whether they have been observed in connexion with its free
and uncombined state, or in its form of continouous circulation, as displayed in the

* The galvanic, or electro-motive apparatus may be considered, «« as producing, by
the mutual contact of the heterogeneous bodies w'hich composed it, a development of
electricity, which is propagated and distributed through its interior, by means of the
conductors interposed between its metallic elements (plates.) If we form a communi-
cation between its two poles, the discharge xvhich follows, overturning the state of elec-
trical equilibrium, in the series of bodies super-imposed on each other," (and forming
the voltaic pile,) "causes them to be recharged, according to the conditions of this
equilibrium, either at the expence of the ground, or by the decomposition of their na-
"iiral electricities. The repetition then of such discharges, or rather their continuation,
must occasion in the apparatus a continued electric current, the energy and the quan-
tity of which depend as well on the magnitude and the nature of the metallic element^
in contact with each other, as on the greater or less facility, which the conducting parts
of the apparatus present to the transmission of electricity." — HIQT.

78 APPENDIX.

various galvanic processes, have been lately, very closely marked and reduced even ta
precise calculation. From among these we may adopt the following general law, which
has been clearly established by M. Biot, namely ; tiiat « each of the two electrical princi-
ples is a fluid, -whose particles, perfectly moveable, mutually repel each other, and attract those
of the other principle, -with forces reciprocal as the square of the distance. JHso at equal dis-
tances the attractive power is equal to the repulsive."

This, therefore, being an established law which characterizes the actions of these fluids,
is it not reasonable to explain the material phenomena of the universe by its assistance,
especially when sucli an explanation may be conducted in accordance with the known
laws of matter, and supported by the conviction that the atoms of every material sub-
stance possess certain electrical states ?

Another very important law which regards the electric fluids, chiefly with respect to
the atoms of matter with which they are associated, must not be overlooked : viz. " that
a mutual attraction exists between tixe electric fluid and all material substances, when
they are in their natural state of electricity." Hut this is a mere extension of the for-
mer law as regards the connexion of these fluids, with the atoms of matter, and is en-
tirely the result of the electrical influence with which these atoms are endowed, as we
can have no idea of matter devoid of its natural electricity.

Proceeding, therefore, upon the established laws of electricity, and upon these which
it is presumed, the particles of matter obey, it may be concluded that the cohesion
which exists between the atoms of unorganized substances, results from the attraction
existing between the opposite electricities. Whether we conceive the particles of
matter to exist innately endowed with certain electrical states, or surrounded with one
or other of these fluids, according to their reciprocal affinity, still the attraction be-
tween the atoms of matter must be equally the result of opposite states of this univer-
sally diffused agent.

But it may be contended, that as the particles of matter mutually repel each other,
they, therefore, are either altogether devoid of any kind of electrical influence, or are
endowed with the property of mutual repulsion, which they exert notwithstanding the
electrical agency. But this objection is by no means valid, for it may be shown that,
even granting them to possess the property of mutual repulsion, the supposition is fa-
vourable to the theory, and serves, moreover, to account for the varied phenomena to
which the different particles of matter and the electrical fluids give rise.

As, however, we have just supposed that the attraction of matter results from the
atoms being endowed with the opposite suite of electricity, it is as reasonable to sup-
pose, that an opposite condition to attraction must take place when homogeneous par-
ticles, or those possessing the same kind of electrical energy, are brought within the
sphere of action.

From this consideration we are led to the conclusion that attraction and repulsion be-
tween the particles of matter arise as a necessary consequence of the electrical states
of these particles. The various anomalies or peculiar conditions of material substan-
ces can be easily supposed to result from certain degrees of electrical saturation, or
neutralization to which these substances are subjected.

From the consideration of corpuscular attraction and repulsion, the transition to che-
mical affinity becomes evident.

It may be shown by direct experiment, that repulsion, can be produced between two
bodies, by giving one of them an electrical state different from that which it naturally
possesses; t:--at is, by bringing it artificially into a condition similar to the other; so
chemical attraction between two bodies may be increased by exalting the energy of
the electrical states which they naturally possess.

As chemical affinities are the result of attraction or repulsion between the particles
of matter, owing to their electrical conditions, so these affinities will be simple or com-
pound, according to the electric states of the different materials which are brought into
mutual action, and according to the various energies of these states.

Having endeavoured to establish the proposition of different material atoms possess-
ing different electrical states, both as regards its negative or positive modes of exist-
ence, and as respects the energy of each, and having considered such relations suffici-
ent to account for the phenomena of repulsion and gravitation, it becomes unnecessary
to point the application of the cicctrine to the various chemical changes which take
place. However, that such changes actually do occur, after the manner which a priori
reasoning would lead us to expect, is a general inference which presents but very few
exceptions. But our knowledge respecting the abstract state of these substances
which present the presumed exceptions are> as yet so very imperfect, that no con-
clusive argument can be adduced that their chemical combination is not the result of

OF GALVANIC ELECTUICTV.

the electrical states of their atoms, or of these fluids during" their continuous circulation
through them.

The excitement of electricity by means of friction, by compression, by the fusion of
inflammable bodies, by evaporation, by the disengagement of gas, by the disruption of
a solid body, by the contact of dissimilar substances, and lastly by chemical decomposi-
tion— all combine in establishing- the intimate connexion for which we contend.

Whenever bodies, brought by artificial means into high states of opposite electricit;-,
are allowed to restore the electricity ; heat and light are the consequences. [Davy.]

These effects takes place in the same manner if performed in a vacuum. The light
produced in this manner appears from the experiments which have been related, to be of
the same nature with the solar beam, and to be divisible into the prismatic colours. The
light exhibited by phosphorescent bodies, and by matter under its various conditions,
gives similar results. Therefore, from taking a survey of the electrical phenomena, of
those displayed by chemical combinations, and of other manifestations of nature, v/e
are inclined'to adopt the belief that light and caloric (as they exist in the solar rays, and
as they are otherwise produced) are the result of the combination and neutralization of
the opposite electricities, whether taking place in a direct manner, and in their free
state of existence, or through the medium of the particles of matter which they endow;
light being more or less perfect according as the netralization is more or less complete,
and the caloric resulting from the intensity of their action.

Before leaving the consideration of the action of the electric fluids upon each other,
and upon the molecules of matter, it is necessary to remark respecting a property which
the molecules of matter appear to possess under certain circumstances, of arranging1
themselves in definite directions ; — this has generally been called the polarization of
matter — a phenomenon observed in the crystallization of numerous substances, and in
different chemical actions. The polarization of the atoms of matter seems to result
from the electrical states which they acquire from the electricities circulating around
them, and to arise from a property with which the electricities are themselves endowed,
or from their mutual action independently of their connexion with the molecules of
matter. According to this view of the subject, we should be led to expect, that the
electricities, as they exist in the solar beam, unconnected with matter, would give rise
to the phenomenon of polarization, in a similar manner as when their action is ex-

igencies and the mag-
netical attractions, is a subject which has lately interested scientific inquirers through-
out Europe. It would almost seem, from their observations, that manifestations of ths-
magnetic power result from the electrized state of the atoms of the magnet, and their
cpnsequent polarization; and, from the continuous circulation of the electric fluids
either through its substance or upon its surface*.

Since the discoveiy of Galvarii, several physiologists have attempted to explain the
phenomena of the animal world, by imputing the functions of the nervous system to
the electro-motive energy, generated or developed by the cerebro-spinal masses,
Amongst those who have espoused this opinion we may mention Sprengel, Reil, Pro-
chaska, Wilson, Philip, Lenhossek, &c. There can be no doubt that the electricities
circulate through animal bodies in different conditions, and give rise to subordinate of'
fices in the animal economy, under the superior dominion of a vital influence ; and
moreover, that they (or one of them at least) are of a stimulus to to this influence.
The experiments of the physiologists just named, especially those of Dr. Philip show
this, but nothing more than this. They refer to the electrical apparatus which certain
fishes possess, and the power they have of giving electrical shocks in farther proof of
the justness of their inference ; but it may be asked, if the nervous influence be the
same as electricity, why should these animals possess an apparatus distinct from the
nervous system, and under its control, for the production otthe electrical phenomena ?
The existence of this apparatus confirms the proposition we have just now stated ;

* In the annual oration delivered to the Medical Society of London in 1822, we en-
deavoured to show that the phenomena of attraction or gravitation, chemical affinity,
combustion, chrystillization, magnetism, light and heat, (both as they exist in the solar
rays, and as they are otherwise produced,) in short, that all the phenomena of the in-
organized world and of the solar systems may be explained by means of the agency of
two universally diffused electricities.

$0 APPENDIX.

snd its office is evidently that of accumulating1 within itself, in consequence of the
vital function with which it is endowed, the electricities circulating- in the body, so that
they may be discharged according- to the wants of the animal ; but the electricities
vhich. the anim.il thus accumulates and discharges cannot be said, from the evidence
which we as yet possess on the subject, to be identical with its nervous influence, noir
•\yith the vitality of its system more than oxygen, nitrogen, hydrogen, or any other
fluid constantly present in, circulating through, and con.i/ming with the constituents
of the body, may he considered to be the source of its numerous manifestations. The
one fluid may accumulate in the system as well as the other, by means of the vital
operations of the organ in which the accumulation takes place, and it may be again
discharged in consequence either of an operation determined by the nervous influence,
or of some other process, and in fact, we find such a phenomenon actually taking place ;
but, are we to infer, on that account, that either the one or the other of these fluids
constitute the vitality of the system, or even that they are the source of vitality, when
it can only be shown to be a single function from amongst the many which the animal
exhibits ? We find that electricity is accumulated in, and discharged from, the electri-
cal apparatus of some fishes ; and we also perceive that oxygen and nitrogen are, in
like manner, accumulated in, and diacharged from the swimming bladders of other
iishes ; but these circumstances do not warrant us to infer that electricity is the nervous
influence of the former, more than that oxygen is the nervous influence of the latter;
or, that the vitality of the one is electricity, of the other it is oxygen.

But, although the agency of the electricities have been extended, farther as respects
the animal kingdom, by some physiologists, than well ascertained facts can wan-ant,
it must be allowed, from the evidence which has been adduced, that they give rise to
very important phenomena when they are brought to operate on some of the animal
textures. It is these effects, or rather the stimulus which electricity imparts to the
sensible and contractile parts of the body, that constitute the chief physiological rela-
tions of electricity, and give a degree of plausibility to the doctrines of those who con-
sider that all the animal functions are discharged by the electricities in their electro-
motive condition. These circumstances require that we should notice at farther
length the effects of this agent on the animal system*.

" According to Ritter, the electricity of the positive pole augments while the nega-
tive diminishes the actions of life. Tumefaction of parts is produced by the former,
depression by the latter. The pulse of the hand, he says, held a few minutes in con-
tact with the positive pole, is strengthened ; that of the one in contact with the nega-
tive is enfeebled ; the former is accompanied with a sense of heat, the latter with a feel-
Ing of coldness. Objects appear to a positively electrified eye, larger, brighter, and
red; while to one negatively electrified they seem smaller, less distinct, and bluish, —
colours indicating opposite extremes of the prismatic spectrum."

An electrical practitioner referred to by Dr. Ure, from whom the above paragraph
33 quoted, considers that his experience in the application of this agent in disease war-
rants him in referring its operation to three distinct heads : " first, the form of radii,
,-vvhen projected from a point positively electrified ; secondly, that of a star, or the ne-
gative fire concentrated on a brass ball ; thirdly, the Leyden'explosion."

The first acts, he considers, as a sedative ; the second as a stimulant ; and the last
has a deobstruent operation. Dr. Ure has found that the negative pole of a voltaic bat-
tery, gives more poignant sensations than the positive.

•The experiments of Dr. Philip with voltaic electricity have led him to infer that the
nervous influence is nothing else than this agent. This proposition has already been

* Amongst the living tissues, the nervous is the best conductor of electricity ; there-
fore, when an electrical current is established through the body, it is transmitted by
this texture. If the electrical current consists only of one of the electricities, the
molecules composing the nervous texture tend to propel each other, or to disunite ;
and if the electrical action is very intense, they are actually decomposed, and con;f
founded with the fatty matter which isolate the nervous fibres ; all the functions of the
nerves are instantly d'estroyed, the irritability of the muscles dissipated, and life is im-
mediately terminated. These effects are frequently witnessed from lightning. They
are not confined, however, to the nervous and muscular systems, all the soft parts are
more or less affected ; the blood does not coagulate, owing to the dissipation of the
rital influence giving rise to the phenomenon of coagulation and all the tissues
quickly into a state of putrefaction,

OF GALVANIC ELECTRICITY. 81

noticed, and it will be again referred to ; we shall only observe at this place, that his
experiments appear to show the extent to which the electro-motive agency, transmitted
through their voluntary nerves, may prove a stimulus to particular organs, and enable
them to perform their functions when these functions have been impeded by the re-
moval of a natural and requisite stimulus. We have at another place endeavoured to
Show that the functions which Dr. Philip has imputed to the cerebro-spinal nerves are
actually derived from another source ; that the operations of these nerves (with the
exception of the nerves of sense) are chiefly confined to the transmission of the cere-
bro-spinal influence, which is the natural stimulus to the vital endowment that the or-
gans receive from a different system — the ganglial ; but that this stimulus cannot be
considered to be galvanism, merely because galvanism is a stimulus, and acts in a man-
ner which we have every reason to suppose other stimuli would act, if they were capa-
ble of being transmitted through, and be present in, every part of the body, on which
they are disposed to operate. It is the particular constitution of this agent, its pro-
perties, and its relations with the solids and fluids of the body, that give rise to its ac-
tive operation, and to phenomena liable to be confounded with those of the nervous
system, or even with those of life itself.

What we have just new adduced has a stricter reference to the opinions of those
who consider that the nervous influence and galvanism are the same, we shall now re-
fer more particularly to the notion of the identity of this agent and life itself ; and
here we cannot do better than quote the very acute, conclusive, and unanswerable ob-
servations of Dr. Pring* (Principles of Pathoiogii^ on this subject. *' We observe that
electricity is related with life, and acts upon it T this is no proof of identity. We ob-
serve also that electricity will substitute in some instances the properties derived from
a nervous centre ; in this respect there is an identical property common to it and life,
which is also possessed by many other substances. We observe, also that the forma-
tion of heat, and the faculty of generating electricity, belong1 to animals, and are de-
pendent upon their life. The faculty of generating electricity, in animals, does not
prove that electricity is even a constituent part of their life : it proves that it is a phe-
nomenon of their life ; but that it is a part of it, is no more to be concluded on this
account, than that urine, or mucusj &,c. is a part of life, because these are also products
of it.

" We have made out then only one point of resemblance between life and electri-
city, which is, that electricity will in some cases substitute a property otherwise de-
rived from a nervous centre ; which property, applied to the stomach, will aid diges-
tion, in which respect, it has not yet been "found that more common stimuli resemble
it : applied to the voluntary muscles, it will produce their contraction, and in this re-
spect the property is a common one to many other substances, which no one ever
thought of identifying with life. But even the properties which are said to depend
upon a nervous centre, are not all of them substituted by electricity, which will stimu-
late muscular contraction, like many other substances, but like those substances also,
it is incapable of conferring sensibility ; or if electrical influence ever excites sensation
in paralytic limbs, it is only because their sensibility is not totally extinct, and will
therefore admit of sensation under the application of this, or of any other stimulus, of
a powerful kind.

" We have seen that electricity can do a very little which is also done by life ; there
is then analogy in one property, but to be the same identity, there must be analogy in
all ; or to approach to such identity there must be at least a general analogy. The liv-
ing principle maintains itself by assimilation from exposure to its elements ; electricity
is not capable of maintaining itself from its elements, but must be produced from them.
Muscular power in the animal system is related with mind, and directed by volition ;
we have no evidence that mind, or volition, independently of the properties which dis-
tinguish t'ue living state, can so ally itself with electricity.' Animal life confers sensibi-
lity on structures ; electricity can merely excite sensation in common v ith chemical and
mechanical stimuli. The organic life produces from a common material, arranges and
renovates, in the muscular system, the particles which compose muscle ; in the tendons,
those of tendon ; in the membranes, those of membrane : in the bones, the constituents
of these structures ; and of all otlu "s, with all their circumstances, however diversified,
Now if electricity were capable of doing all this, there would then be established only a
general resemblance with life ; analogies would afterwards be sought for, corresponding

* We recommend the physiologist to study closely the physiological and pathologi-
cal writings of this most acute and philosophical writer.

Li

82 APPENDIX.

with these powers exhibited by the relation of properties of life in different seats, and
more especially among the phenomena of disease. But until the pretensions of elec-
tricity to an identity with life shall be established by rather a more extensive analogy,
it is superfluous to inquire how far the phenomena of electricity resemble those of dys-
pepsia, diarrhoea, consumption, abscess, or gout. If, perchance, electricity should be
endowed with the properties engaged in these phenomena, it will be greatly indebted
to its friends, for bestowing upon it attributes which it has never displayed. In the
mean time, it is to be wished that experimentalists will go on multiplying their facts,
and that they will abstain from reasoning upon, them : they will not, however, err to
to any great extent in this way, if they will take the trouble to remember that so far as
things are proved to be alike, they are alike ; and where they are not proved to be
alike, it is possible that they may be different.

"The identity of life and electricity, or galvanism, has been inferred, as appears
from the preceding account, from very slender premises: but the arguments just con-
sidered are among the best that have been, proposed in favour of the sameness of the
two principles, or substances, if they are substances,"

Of Ossification,
Note HIT.

The bones are at first of a mucous or gelatinous consistence in the embryo. TtV;
r.ext become cartilaginous, and some of them fibro-cartilaginous ; they are lastly per-
fectly ossified. At the early period of the embryal state the bones gradually increase,,
without any apparent division, into separate parts. The cartilaginous bones, or the
temporary cartilages, do xot appear before two months have elapsed from the period
of conception, and then this process towards ossification only commences in those
bones, or in the parts of bones which are ossified at a later period. It appears doubt-
ful whether or no those bones which ossify the first, or those parts of bones in which
the process takes place at an early period, pass through an intermediate or cartilagi-
nious state. It seems most probable from the observations of Messrs. Beclard and Ser-
res, that in them the ossific deposit is made in the first or mucous state of their exist-
ence ; whilst, in those bones which are perfected at a remoter period, the cartilaginious
or intermediate state which they assume is rather a provisional function, than a stage ot
ossification— a temporary condition of structure forthe purpose of performing the offices
of bone, and not a requisite antecedent to the ossific process.

Ossification commences successively in the different bones, from about a month after
impregnation, in those which are the first formed, until ten or twelve years after birth,
in those which ossify at a later period ; and in certain subordinate parts of bones, the
ossific process does not commence until the fifteenth or eighteenth year. The clavicle
MK! maxillary bones are amongst the first developed ; the sternum, the bones of the
pelvis, and those of the extremities are the latest. It may be considered as a general
proposition that those bones which are nearest the nervous and sanguineous centres
are the first to be formed, as if their more immediate developement were required to
protect these important systems ; hence we perceive that the vertebrae and ribs ossify
at an early period.

At the end of the first month ossification commences in the clavicle, and successively
in the inferior maxilla, in the femur, tibia, humerus, superior maxilla, and bones of the
fore-arm, where it begins about the thirty-fifth day. About the fortieth day this pro-
cess commences In the fibula, scapulum, the palatine bones ; and during the following-
('.ays, in the occipital and frontal bones, in the arches of the first vertebra:, and in their
sides, in the sphenoid, the zygomatic apophysis, the phalanges of the fingers, the bodies
of the vertebrae, the nasal and zygomatic bones, the ilium, the metacarpal bones, the
condyles of the occipital bones, in the squamous portion of the temporal bone, the pa-
rietal, and in the vomer ; in all these ossification begins about the middle of the seventh
week. In the course of the same week it commences also in the orbitar process of the
sphenoid ; and, about the end of the week, in the metatarsal bones and phalanges of
the fingers and toes. During the ten following days it begins in the first sacral verte-
bra:, and around the tympanum. During the subsequent weeks and months it com-
mences in the bones or the ear, in the pubis, in the processes of many of the already
mentioned bcnes, in the small bones of the extremities, 8cc. (Beclard.)

OF VOICE. 83

Ossification docs not result, as we have already noticed, from the transformation of
cartilage into bone. The diaphysis of the long" bones, and the centre of the large
bones, which are amongst those first formed, pass immediately from a mucous to an os-
seous state. The other parts of this structure have an intermediate cartilaginous con-
dition ; and it is in these parts that the successive stages of ossification may be best ob-
served.

The cartilage which, for a longer or shorter period, supplies the place of bone, be-
comes at first hollowed into irregular cavities, afterwards into canals lined with a vascu-
lar membrane and filled by a mucilaginous and viscid liquid ; these canals become red,
the cartilage now assumes an opaque appearance, and ossification commences towards
its centre. The first point of ossification is always in the centre of the cartilage, and
never at its surface. This point is surrounded by a reddish cartilage, and that part
which is nearest it is opaque and pierced with canals still farther than opacity reaches.

The osseous point augments progressively by means of additions on its surface, as
well as by an interstitial deposit in its substance. The cartilage gradually becomes
hollowed by cavities and canals, lined by a vascular sheath, diminishes as the ossifica-
tion extends, and disappears altogether when the process is completed.

With respect to the state in which the osseous matter is formed, we are inclined to
agree with Mr. Beclard, in the opinion that the earthy matter is deposited, in a fluid
condition, and at the same time with animal matter, jn the organized tissue which se-
cretes it. Its subsequent solidification arises either from the deposition of a larger pro-
portion of earthy matter, or from the absorption of the vehicle which gives it the fluid
condition ; or from the joint operation of both these causes.

Of Voice.
Note HH*.

The cricoid cartilage, which supports the two arytenoid cartilages, is not immovea-
ble at the inferior part of the larynx. The trachea to which it is attached by its inferior
margin, yields and elongates itself in order to allow it motion. The muscles of the
Sarynx do not contribute to the production of the voice solely by means of the action
which they exercise on the sides of the glottis ; several of them, and particularly the
thyro-arytenoids, may be considered as forming part of the parietes of this opening.
These small muscles give rise to acute sounds by drawing closer the two arytenoid car-
tilages, and when in a state of contraction they also seem susceptible of a vibratory uio-
tion, varying iu degree according to the degree of contraction : by the assistance, there-
fore, of the muscular fibres covering its sides, the glottis is susceptible of vibrations
snalagous to that of the lips applied to the opening of a French-horn. The production
of sound is owing to the action of the muscles of the larynx on its cartilages, during ex-
piration ; and whatever impeds the functions of the nerves actuating these muscles,
puts a stop to the utterance of sound.

Of Ventriloquism. — Various attempts have been made to explain the manner in which
the ventriloquist is enabled to modify his articulations into the semblance of distinct
voices. Dr. Good considers ventriloquism " to be an imitative art, founded in a close
attention to the almost infinite variety of tones, articulations, and inflexions, which the
glottis is capable of producing in its own region alone, when long and dexterously
practised upon ; and a skilful modification of these vocal sounds, thus limited to the
glottis, into mimic speech, passed for the most part, and whenever necessary, through
the cavity of the nostrils, instead of through the mouth." He farther supposes that
" some peculiarity in the structure of the glottis, and particularly in respect to its mus-
cles and cartilages," is requisite to carry this art to perfection. The explanation -/rhich
Magendie otters on this subject, appears to us to be more correct, although perhaps not
sufficiently so. This physiologist asserts, that ventriloquism consists in certain modifi-
cations of sounds or speech, produced by a larynx of the common formation, with a
strict attention to the different effects of sound thrown at different distances, and
through different modes of conveyance. We cannot agree with Dr. Good that the
ventriloquist performs articulation by means of the larynx only, although we may con-

84 APPENDIX.

cede some share in the process to this organ j nor can it be granted that any " addition
to the muscular organism of the glottis" is enjoyed by those who have perfectly ac-
quired this imitative art.

Of the Generative Organs and their Functions.
Note I.I.

I. Of the Male Organs of Generation — -The cellular structure of the corpora caver-
nosa penis, according to the microscopic examinations of Mr. Bauer, appears to be made
up of an infinite number of thin membraneous plates, exceedingly elastic, so connected
together as to form a trellis work, the edge of which is firmly attached to the strong1
elastic ligamentoiis substance which surrounds the whole, and also forms the septum pec*
tint-forme. This substance has an admixture of muscular fibres The cells are generally
larger, or rather the trellis work is more loose in the middle portion of each corpus ca,-
vernosum. -

Arterial ramifications are supported by this reticular structure, and they are distribut-
ed every where througout the cavernous part of this organ. In the usual state of the
penis, the blood is not poured into the cells, but returns by the veins, and it remains
flaccid; but when a person is under the influence of particular impressions, the minute ar-
terial branches which before had their orifices closed, now have their actions suddenly
increased, and pour from their open mouths the blood into these cells so as to overcome
the elastic power that under ordinary circumstances keeps them collapsed.

The corpus spongiosum penis appears, from the observations of the same physiolo-
gist, to consist of the same kind of structure as that observed in the corpora cavernosa,
but on a less scale. Its structure iso als more regular throughout ; without, however,
having any muscular fibres mixed with the trellis work, these being confined to the
outer surface of the inner membrane of the urethra. The erection of this part is sup-
posed to^take place after the same manner as that of the corpora cavernosa, namely,
from a vital expansion taking place in the extremeties of the arterial capillaries, and
thus allowing the blood to flow from them into the cells of both structures.

We may state, moreover, that the arteries of the penis are surrounded by a larger pro-
portion of nerves than in most of the other tissues of the body. The veins form very
numerous anastomoses. It is the division, on dissection, of these numerous veins, and of
their numerous roots, anastomoses, and plexuses, which in the opinion of M. Beclard,
gives the appearance of cells, the existince of which he denies. Erection of this tex-
ture is the result of the influence of the nerves upon the arteries and veins belonging to
it. By this influence the action of the arteries is increased, whilst the diamter of the
veins returning, the blood is diminished by the tonic contractility which these nerves
exert on the coats of the veins.

Messrs. Prevost and Dumas have both examined the spermatic animalcule. They
seem to vary in form in different animals, and to be the product of a real secretion,
These physiologists conclude, " 1st, that spermatic animalculae have nothing in com-
mon with infusory ones, except in their microscopic size ; 2d, that they are produced in
the testes alone, but do not appear in these organs till the age of puberty ; and 3d, that
they seem to be the active principle or agent of the semen."

The vesiculx seminales may, under particular circumstances, more likely to occur in
the human species than in 'the lower animals, be employed as reservoirs ; although
their ordinary use may be to secrete a fluid which, mixing with the semen in coitu, may
render the act more perfect, and more likely, therefore, to produce fecundation.

II. Of the Female Organs of Generation, — The uterus, the ovaria, and the fallopian
tubes receive their nerves from the abdominal portion of the trisplanchnic nerves, bran-
ches of which unite variously with each other, and form six plexuses. The first, which
M. Tiedemann calls spermatic, or the ptexus common to the ovaria and tubes, is situat-
ed on the anterior surface of the abdominal aorta,and on the origin of the internal sper-
matic artery. It is formed of a number of branches, which come from the renal ganglia.
Its iilaments descend, surrounding the arteries of the ovaria, between the membranes
which form the broad ligaments of the uterus, and arrive at the ovaria and tubes, in
•which they are ramified : a few filaments reaches the fundus of the uterus.

The second plexus, which is the largest, Mr. Tiedemann calls the superior lumbar plex-

OF THE GENERATIVE ORGANS, ETC. 85

y.v, or common uterine. It is formed of branches, which proceed from the superior lum-
bar and renal ganglions ; and is placed on the body of the fifth lumbar vertebra, and 011
the promontory of the sacrum, between the iliac arteries. On its entrance into the pel-
vic basin, it divides itself into two considerable plexuses, which M. T. calls the hypo-
gastric or lateral uterine plexuses. These are placed on the trunks of the iliuc arteries,
and anastomose with the first and second sacral ganglions. A great many filaments pro-
ceed from these plexuses, forming a reticulum around the arteries of the uterus, with
the ramifications of which they penetrate into the texture of the organ, ckiefly its pos-
terior and lateral aspects.

Several branches proceed from the superior lateral or hypogastric plexus to the vagina,
at the point of its union with the neck of the uterus, and there unite with the anterior
branches of the third and fourth sacral nerves, and form a large plexus, which M. Tie-
demann calls the inferior lateral hijpogastric, and which interweaves with and embraces
small ganglia. The gangliform plexus gives origin to a great many branches, chiefly to
the vagina, to the uterus, and also to the bladder and rectum. These nerves, as well
as those belonging to the other plexuses, always closely embrace the arteries in the
form of a net work.

It appears, therefore, that the womb and its appendages are surrounded by important
nervous plexuses. These nerves are soft, small, reddish-gray, and in every respect si-
milar to the other portions of the great sympathetic nerves. Of their appearance and
character we have had several opportunities of satisfying ourselves, when making re-
searches respecting this grand organic system, and we can bear testimony to the cor-
rectness of the observations of M. Tiedemann.

M. Tiedemann states that the number and size of the uterine nerves vary according
to the age of the female ; that they are small and apparently few in girls — large and
numerous in adults — and very small in old women. He has observed another fact, con*
firmatory of their functions which indeed was previously noticed by Dr. W. Hunter and
Professor Chaussier, that these nerves become larger and more numerous during ges-
tation.

III. Of Impregnation. — Several opinions have been entertanined respecting the im-
pregnating process. Some physiologists suppose that the actual contact of the ovum
and semen are requisite ; others that the aura seminalis is all that is requisite. Of the
former cfass of physiologists some suppose that the semen is absorbed into the uterus,
where the ovum, having descended through the fallopian tubes, meets it ; others con-
sider that the semen is conveyed by a paristaltic-like action of the vagina, uterus, and
tubes, to the ovarum ; and the}' adduce, in support of their opinion, the occurrence of
extra uterine fcctation ; a third party, belonging to this class, conceives that the semen
is conveyed to the ovum itself, in its situation in the ovarium, by means of absorption
through a set of vessels allotted to this specific purpose. Dr. Dewees, of Philadelphia,
has argued strenuously for this last doctrine : it has also been adopted by other physio-
logists, and it seems to have received support from the labours of Dr. Gartner, of Co-
penhagen, who has discovered in some animals a duct leading from the ovary to the va-
gina. The occurrence of ovarian foctation, wherein the foetus is lodged within the en-
veloping membrane of the ovarium, can be most satisfactorily explained by means of
this doctrine. Two cases of this description have lately been detailed by Dr. Gran-
ville and Mr. Painter. It must, however, be allowed that the latter class of physiolo-
gists, or those who contend for the impregnation influence of the aura seminalis, have
it in their power to adduce strong arguments in behalf of their opinion. It has even
been asserted very recently, by some continental physiologists, that the impregnating
power of the aura seminalis may be proved by experiment performed on rabbits, in the
following manner : Let the semen be received in a cup, over which is to be immedi-
ately placed an inverted funnel ; and let the apex of this funnel be introduced into the
vagina. If this experiment be performed immediately after the seminal emission, they
say that impregnation will be the result.

It has been argued that the venereal desire is present in neither sex before the de-
velopment of the testes and ovaria. This, however, is not the case. The venereal
appetite makes its appearance in both girls and boys long before the generative organs
are developed. It has been frequently observed in them both, in temperate cb'mates,
as early as the sixth or seventh year. It has also been supposed that the venereal ap-
petite disappears soon after the menses have ceased to flow : this also is not the case.
With respect to the assertion that the venereal orgasm on the part of the female is
necessary to impregnation, we may observe that although it may be requisite in

8G APPENDIX.

some females, it is by no means so in others ; for many women conceive, who are indif-
ferent during- the venereal congress; there are others who conceive, notwithstanding their
successful endeavours to suppress their orgasm ; and some are impregnated, when owing
to disease, as procidentia uteri, &c. they cannot be supposed to enjoy much pleasure
from the act.*

Dr. Blundell found in his experiments that when only one of the uteri of a rabbit was
divided* or rendered impervious at its neck, or when the passage to both was obstruct-
ed by tying the vagina, and iifterwards freely admitted to the male, that the obstruct-
ed uterus, or uteri, did not become impregnated ; but he found, in those whose vagina
was tied, that, notwithstanding, the ovaries, fallopian tubes, and womb were excited by
coition; and in those who admitted the male frequently, the abdomen acquired a large
size, and in some cases exceeded the bulk of mature gestation. These enlargements
arose from an accumulation of a humour in the womb, which, at a temperature below
boiling, formed albuminous concretions. In its appearance it was various, but general-
ly fluid, pale and turbid. In those who had only one uterus obstructed, the sound one
became filled with foetuses, and the barren one with the humour described. The for-
mation of the lutea, the development of the womb, and the repeated accumulations of
fluid in consequence of coition, in these experiments seem to indicate the descent of
the rudimental material.

Thus although the passage to the uterus was completely interrupted, the tubes were
excited by the venereal org'asm, they really conveyed the'rudiments to the womb, and
these rudiments engendered the watery accumulations there in the abortive attempts
at generation. This appears to confirm the supposition, and indeed to establish it, that
even in viviparous animals, generation may be carried to a certain extent, although the
access of the semen to the rudiments is interrupted ; under these circumstances the
young animal cannot be formed, it is true, but corpora lutea may be generated, the
womb may be developed; and the rudiments may be transferred to the uterine
cavity by the play of the fallopian tubes. This opinion receives countenance from the
generation of oviparous animals, in most of whom the rudiments may be discharged
independently of preeceeding impregnation. — (J\Ied. Chirug. Trans. Vol. 10. )

Dr. Blunde'll supposes that the vagina and womb perform a peristatic motion from
the stimulus of the semen, both in the haman subject and lower animals ; and that this
motion conveys the semen to the rudiments.

i'rom these experiments it would appear that the presence of corpora lutea can-
not be relied upon as a proof that impregnation had taken place. There is .even evi-
dence that they may be produced even independently of the sexual intercourse, from
the mere excitement of desire in a high degree. Dr. Blundell has in his possession a
preparation of the ovaria of a young woman who died of chorea under seventeen years
of age, in which the hymen was unbroken, and nearly closed the entrance of the va-
gina. In these ovaries the corpora lutea are no fewer than four — two rather obscure,
the other two perfectly distinct.

As Dr. BlundelPs experiments goto prove that impregnation cannot take place with-
out the semen coming in contact with the rudiments, he therefore supposes, that when
the ovary lodges either in the tubes, the peritoneal cavity, or in the ovary itself, anil
there impregnated, that the semen must be conveyed to those situations. Or, that the

* Sir Everard Home (PMksoph. Tram. 1818) states that corpora lutea are never met
with before puberty. They are formed is the loose structure of the ovarium previous to
and independent of, sexual intercourse ; and when they have fulfilled their office of
forming ova, they are afterwards removed by absorption, whether the ova be impregnat-
ed or not. It seems that the ovum too, with its amnion and chorion, is formed in the
virgin after puberty. This was found to be the case in a woman of 20 years of age,
who had a perfect hymen. "The fallopian tube of that side was fuller than the oppo-
site. The fimbriae were spread out, and unusually vascular." We know that animals
part with their eggs whether there be sexual intercourse or not ; and this is done with
such force during coition that the cavity of the corpus luteum is absolutely inverted, so
that the ovum is exposed completely to the emission of the male. Extravasation of
blood follows the rupture of the ovum frequently to so great a degree that blood occa-
sionally passes out through the vagina. In nine months after impregnation, the cor-
pus luteum is nearly absorbed, but a new one is usually found in a state of forwardness
in the other ovarium. All preparations of corpora lutea, which are made from women
who have died in child-bed, belong, in Sir E.'s opinion, to ova which were to suo
not to the ovum of the child which had been born.

OF THE DEVELOPMENT OF THE FOETUS, ( 37

rudiment in its descent meet the semen in its ascent, and that the transfer of the semen
beyond the womb may be the cause of extra uterine pregnancy.

IV. Of Superfatati'm. — M. de Bouillon (Kullet. de la FaaiL et dfi la Soci&e de
cine, JVb. 3.) has adduced an instance of superfoetation in a Negress. At the end of her
pregnancy she was delivered of two male children, full-grown, and of the same propor-
tions, but the one a Negro and the other a Mulatto. The mother, after a long resistance,
confessed that she had connexion the same evening with a white and a negro. Similar
instances have lately been detailed in the American journals, of which we shall only in-
stance the following : — A white woman, near Philadelphia, is said by Dr. Dewees, to
to have been delivered of twins, one of whom was perfectly white, the other black.
The latter of these had all the characteristics of the African, whilst the former was de-
licate, fair-skinned, light-haired, and blue-eyed. Similar cases have been detailed by
Dr. Elliotson, and Drs. Norton and Stearns," of New-York.

Superfcetation, in our opinion, can only take place under circumstances similar to
those which produced it in the foregoing instances : — in them, it would seem, that there
had been connexion with different individuals within a short space of time. We con-
ceive that, when the decidua is thrown out and the ovium has formed its connexions,
superfostation is then impossible, unless in the case of a double uterus.

Of the Development of the Textures and Organs of the Foetus.
Note KK* -^

It was our intention to have illustrated this subject at considerable length ; but we
have so far exceeded our limits that we must no^ be brief.

At first the embryo appears to be only a semi-liquid vesicle, and to consist of minute
globules disseminated through a more fluid medium, which presents an oval or spheroid
form.* As the embryo advances, the proportion of solid matter increases, and continues
to increase to the termination o.f the life of the individual. The h'rsjt stage of its exist-
ence resembles that oi' the polypus ; and the globules which may be observed in its
otherwise homogeneous texture, closely resembles those which are observed in the
nervous system. At first the embryo is colourless ; it afterwards presents a gradual de-
velopment of colour, and at last, a coloured fluid may be discerned. From a state of or-
ganization, consisting merely of -disseminated globules, fibres, membranes, and vessels,
come Successively into existence. The organs, as we have already said, are not formed
at once : they are gradually developed. Even particular systems do not assume at once
their form of organization, but are developed by degrees, and run through the same
stages of organization as may b$ remarked in the animal scale. This is particularly re-
markable, ss respects the development of the nervaussystem.f (&ee the note on this
subject. )

The exterior form of the fetus seems to be assumed before its tissues attain any conside-
rable degree of consistence. The glandular viscera are at first formed in isolated parts. The
globules of the nervous system first appear ; these become united into cords and gan-
glia, t The vessels commence in isolated vesicles, which become elongate^ and connected

* Mr. Bauer says that he has detected the human ovum on the eighth day from co-
ition. It consisted of two membranes ; the external one open throughout its length,
but with its edges turned inwards, like the shells of the g-enus voFuta ,• the internal
membrane pointed at one end and obtuse at the other, slightly contracted in the mid-
dle, and containing a slimy fluid and two vesicles.

f It would appear that in the process of the growth of the embryo, even of man?
that, during the first days of its existence,, the nervous system can only be traced as it
exists in the polypi ; its globules seem dispersed through the embryal structure : as
the ovum advances the ganglial branches, and the ganglia themselves make their ap-
pearance.

-t Viewing the nervous system throughout the numerous classes of animals, and
tracing the process of its formation from the embryo up to the period of perfect fatal

88 APPENDIX.

uf regular series. Tlte intestinal tube seems to be the viscus, which first presents a defihitfi
conformation. It is at first straight, and afterwards it curves forwards, and is embraced by
the umbilical chord : it thus forms an angle and descends into the abdominal cavity, which
is open at its anterior aspect, and apparently continuous with the short and imperfectly de-
veloped chord. This turn of the intestinal canal, and its retention in the chord, seems to
form the umbilical vesicle, and the subsequent strangulation of the intestine by the constric-
tion and elongation of the chord first gives rise to an insulated appearence of this vesicle sub-
sequently, to its entire disappearAce, and lastly, to the separation of the intestines; tlie
vermiform appendix remaining as a type of the original conformation.

About the same time that the intestinal tube curves into the umbilical chord, the urina-
ry bladder seems to be also prolonged into the chord, between the chorion and amnion,
forming the allantois and urachus, the former of which disappears as the fa-tus is developed
and the chord lengthened, the urachus only remaining at the time of birth, showing the
nature and type of the original conformation and the communication formerly existing be-
tween the allantois and bladder.

We have already said that all the phases, through which the human embryo passes until
its conformation is perfected, correspond with the different stages of permanent organiza-
tion which characterize the animal scale. Since these observations were made, we perceive
that a similar opinion has been lately entertained by J. F. Meckel, and adopted by M. Be-
clard, in his recent and excellent work on General Anatonvy. Many proofs may be addu-
ced in support of this doctrine: so evident indeed is the analogy that a very close parallel
may be drawn between the stages of development through which the human foetus passes,
and the degrees of animal organization.

The human embryo is at first an imperfectly formed vesicle ; such are the polypi and
others of the Zoophytes. At a remoter period it consists of a small vermiform body
without a distinct head, ov limbs ; sftch are the Echinodermata, and the Annelides. At a
still later period its limbs ; are equally developed, and its tail is prominent: such are the
Quadrupeds.

As respects the nervous system, the ganglial or vital nerves first appear with their gan-
glions : such is the nervous structure of the invertebrated animals. As the embryo advan-
ces, the ganglial nerves give rise to two thin strips of medullary matter in the situation of
the spinal canal, these increase, coalesce, form the spinal and cervical marrow, (medulla
oblongata) and the tubercles of the latter, whence are produced the brain and cerebellum;
we observe the same conformation in reptiles, fishes, &c.

The human foetus is remarkable for the rapidity with which it runs through the early
grades of the scale of organization. It is this circumstance that renders the early changes
which it experiences so difficult to be recognised.

II. Of the circulation of the Fcetus.— There are abundant facts to prove that the circu-
lation of the foetus is independent of that of the mother; that the blood of the former flows
from the umbilical arteries into the vein of the same name, and not from the uterine arteries
into that vein; that the foetal blood is fabricated by the foetus itself, from the juices furnish-
ed by the mother to the placenta, and, consequently, that the foetus (toes not receive one
drop ready formed from this organ by the umbilical vein.*

existence in the perfect animals^ especially in man, we are led to infer that this system
is not originally formed from the centre towards the circumference, but that the origin
of its ramifications commences in the mucous or cellular tissue, when the embryo is
yet but in an apparently homogenious state ; and that as the textures become, in the
process of foetal growth, more and more developed, so the globules composing the
nervous system, and chiefly those of the g'anglial System of nerves are arranged into
cords of communication, chiefly in the course of the vessels, for the purpose Of pre-
serving communication between the organs, and reinforcing each of the textures with
the influence which they generate in their perfect state of development. As the pro-
cess of foetal growth proceeds, the nervous ramifications advance towards centres,
which vary in their characters, according to the species of the animal ; in those which
are more perfect those centres are numerous, and almost each differs in a more or less
sensible manner from the other, both as to appearance and function.

* D. F. Lavagna concludes that the menstrual blood differs from common blood, only
in containing no fibrin ; also, that the blood in the uiribilical arteries of the funis contains
scarcely any fibrin, whilst that in the umbilical vein forms a tenacious jelly; hence, he in-
fers, that the blood acquires fibrin in the ciculation in the placenta, which it parts with in
its passage through the foetus — Annali di Medicina di Milwio, JVo. 17.

ON THE DEVELOPMENT OF THE FCETL'S. £9

la proof of the correctness of this opinion, we may refer to the experiments performed by
M. Gaspard, (Jourtt. de Physiul. Experiment, No. 3,) in order to ascertain this point, and
to the formation of blood in the impregnated egg on the second or third day after incuba-
tion, and to the fact that, in the numerous tribe of oviparous animals, the foetuses are insu-
lated from the mother, and are the real manufacturers of their own blood.

At an early period of fcctal life the ganglial ramifications and centres are first formed,
and afterwards the ramifications and centres of the voluntary nerves. In the more perfect
animals, even that part of the nervous system which is general throughout the animal crea-
tion, and which the lowest orders of it possess, is the first formed, and that part which is
destined to perform the highest functions, and which the perfect animals only possess, is
produced the last.

Other peculiarities of the fcetus are adduced in the subjoined notes: —

Of the Development of the Heart and Ltaigs. — J. F. Meckel has concluded from his ob-
servations, 1st, The heart is relatively larger the younger the embryo. For in his observa-
tions he found, at the first period, at which the heart could be distinguished, that it filled
completely the thoracic cavity.

2d, The heart is more symmetrical with respect to situation and form, soon after its for-
mation, than at a more remote period.

3d, The form of the heart undergoes various changes during the growth of the ftetus.

Jl. The proportion between the arterial and venous portions of the heart is not always
the same. The auricles surpass the ventricles in capacity, in proportion as the embryo is
younger.

.B. The relative volume of the two sides of the heart is not always the same at all pe-
riods. In the adult the right side always more or less exceeds the left; but in very young
embryos the two ventricles are equally capacious, but that of the right side increases ra-
pidly. The right auricle surpasses the left in size in the foetus, and it is only by degrees
that the left becomes equal to the right.

C. The right ventricle is unquestionably smaller than the left at first.

D. The thickness of the parietes of the heart is much more considerable at first. The
two halves of the heart equally present this difference, but the right ventricle always ap-
pears a little thicker than the left. This is, however less, the younger the foetus.

-B. The two ventricles communicate with each other at an early period, and, according
to all appearances, continue to do so until the end of the second month, by means of an
opening in their interior aspects, situated at their base, and immediately beneath the origin
of the great vessels.

F. The interior disposition of the auricles with respect to their communication, either
with one another, or with the venous trunks, undergoes considerable changes. These turn
chiefly on the form and size of the oval hole, the situation of the orifice of the vena cava
inferior, the situation, the form, the extent and relations of the valve of Eustachius and
thit of the foramen ovale. Here M. Meckel's researches confirm those of Sabatier and
Wolff.

1th, The disposition of the aorta and of the pulmonary artery offers several considerable
changes, in succession, of which the following are the chief.

A. At first there exists only an aorta. A pulmonary artery is formed at a remoter pe-
riod. It is not until after the seventh week that the pulmonary artery begins to appear,
and then it is only a second aortic trunk, as yet without branches — a right aorta, proceeding
in the direction of the lungs, which are very distant, and extremely small.

The disposition of tLe large arteries at this period (seventh week) nearly resembles what
it Continues to be, in reptiles, during the \vhole life of the animal.

B. It is in the course of the eighth week only, in which the branches of the pulmonary
artery can be discovered. They are then much smaller, when compared to the trunk of
the artery and to the arterial canal, the younger the embryo. At five months they become
equal to this canal, and afterwards they surpass it, frequently so far that when the fcetus
has completed the ninth month, each principal branch of the pulmonary artery is as large
as it is, or even larger.

The venous canal presents similar appearances. It is during the first periods of the ex-
istence of the fetus when it offers, proportionally, the greatest amplitude. All the obser-
vations which M. Meckel has made, confirm this law, which is the more important as it
throws considerabie light on the functions of this canal. Indeed, it is probable that this
conformation is only the remains of a disposition which may be seen at the epoch when the
liver has not come into existence, when the vena porta and the vena cava inferior form but
one trunk, as the pulmonary artery forms, at the early stage of its existence, only one with
rta. This conjecture respecting the origin of the venous canal is confirmed by the or-

i^j APPENMX

ganization of the acephalous class of animals, in which the veins of the intestinal cana'i,
and Consequently the vena porta, also, open immediately into the vena cava inferior.
5th, The lungs are not formed until a more advanced period.

In man, manifest traces of them cannot be seen before the sixth or seventh week. Then
they advance beneath the heart, at the two sides of the inferior extremity of the pectoral
portion of the aorta. At the period of their appearance, and even for some time afterwards,
they are so small, in proportion to the heart and the other organs, that it requires the great-
est attention in following their progressive development, to be convinced that they are ia
reality the rudiments of the respiratory organ.

At first the lungs closely approach one another: they are flat and of a whitish colour.
Their surface is perfectly united ; but, on their external border, may be observed, at an
early period, indentations, which are the traces of the approaching separation of the lobes,
notwithstanding that these lobes are not yet in existence. At a farther advanced period
the lobes appear to be composed of lobules. These latter are at first larger and much less
numerous, in proportion, than at subsequent periods, but they separate by degrees into
others much smaller. At the period when they are first observed, they are as much more
apparent, and as much less intimately united, by cellular tissue, as the embryo itself is
younger.

6th, As the lungs become developed, in the reptiles and leeches, in the form of an empty
sack, it is natural to suppose that their production, in animals of a higher order, takes place
according to the same manner and law. M. Meckel endeavoured to ascertain whether or
no this was actually the case. But, under whatever aspect he viewed the lungs at the ear-
ly stages of their formation, even with the assistance of the microscope, he always found
the slices which were removed from them completely solid; if they are really so during this
epoch, it would seem as if they had some analogy of structure with the Branchiae of fishes.
7th, The branches of the pulmonary artery, which proceed from the right or pulmonary
aorta, are at first certainly wanting. It must therefore be admitted that at this epoch,
their places are supplied by the bronchial arteries, especially by the inferior, since the lungs
are at first placed low in the inferior part of the chest. Moreover, this depending situation
of the respiratory organ, at the •commencement of its development, is remarkable under two
points of view:

Jl. Since, amongst reptiles, and many of the mammiferi, the lungs are placed much lower
than in man, and below the heart, in every respect like the fishes, the swimming bladder
is placed below this organ.

B. Because it seems that the lungs and the thymus gland correspond in their functions,
the development of the one being in direct proportion to the decrease of the other.

L F. Meckel concludes from the researches of which we have given an abridged outline,
that the general results confirm it to be a grand law of the animal economy, that the em-
bryo, from the instant of its formation until that of its maturity, rises successively through
many inferior grades of organization, and that the principal monstrosities of the heart and
large blood-vessels depend upon these organs being arrested at some one grade or degree of
organization, instead of following the progress of the others towards perfection.

Respiration of the Foetus. — The thymus gland appears to assist the placenta, the liver,
and the secretion cf fat, in the respiration of the foetus, or rather in purifying the blood of
the foetus. It seems to form a nidus for the reception of those elements of the blood— ^-car-
bon and hydrogen, which are secreted in a state approaching to fat, and which if too abun-
dant in this fluid, would endanger the existence of the foetus. These materials on the com-
mencement of active respiration are again absorped, to be discharged from the economy by
the lungs, liver, or intestinal canal. The thymus gland in the human foetus, in the ninth
month, generally weighs from 160 to 180 grains; at 28 years of age only 90 grains.
In the calf it weighs 16 ounces, in the cow 9 ounces.

*' Etenim placenta, hepar, adipis aucta secretio respirationi, sed aliud aliomodo, inser-
viunt. Quoe naturre institutio, ut in foetu organon alterum alterius vices obtinere possit,
pulcherrima et prsestantissima; quo fit, ut foetus vita nondum autonomica, a noxiis qtiibus-
cunque momentis, quae vim in ipsum habere possunt, tueatur conserveturque, donee ex
asylo matris in lucem aeremque editus vim innatam exerceat.

Vena umbilicalis illo principio (oxygenio) gravida partim in hepar, partim in venam ca-
vam inferiorem sanguinem reducit a partibus phlogisticis liberatum. Itaque vepa cava in-
ferior, postquam sangninis partem ex vena umbilicali et venis hepaticis excepit, prater san-
guinem oxydatum, venosum quoque sanguinem ex corporis partibus reducem continet, cujus
tamen pars satis magna, sanguis lienalis ac meseraicns, in hepate jam carbone relicto, mera
existit. Quoniam vero vena' cava inferior prima vitae foetalis parte magis in sinistrum quam
in dextrum cordis atrium aperitur, sanguis autem venre cavae superioris, nil minus quam
oxygenium ducens ex dextro cordis atrio per arteriam pulmonalera, hinc per ductum Botal-
licura, demum, postquam jam arteriac superiorum partlum ex aorta oxcreverun1-, in ipsaia
perfunditur;— -sequitur caput atque extremitates superiores sanguinem magis oxydaturn,
sen, si mavis, dephlogisticatum, in atrio sinistro ventriculcque congestum, accipere: — aor-

,iE MORTALITY OF KKMAL1IS.

Of the Varieties of the Human Specif ^
Note L. L.

BufFon, Blumenbach, Prichard. Gavoty and Touluzan, Cuvier, and others, have propos-
ed classifications of the varieties of the human species: of these we prefer that of Cuvior.
The following is an outline of it: —

1st, The fair, or Caucasian variety; 2d, the yellow, or Mongolian; 3d, the negro, or
Ethiopian.

1st, CAUCASIAN. Characters. The beautiful form of the head, the variable shades of
complexion, and colour of the hair.x

Principal Branches. 1, The Syrian, whence have proceeded the Assyrians, the Chal-
deans, the Arabs, Phoenicians, Jews, the Abyssinians, Arabian colonies, and ancient Egyp-
tians. 2, The Indian, German, or Pelasgic branch was early subdivided into the Sanscrit,
the Pelasgi, the Teutonic, and Sclavonian. 3, The Scythian, or Tartarian branch.

2d, MONGOLIAN. Characters. Prominent cheek-bones; flat visage; narrow and oblique
eyes; straight and black hair; scanty beard, and olive complexion. Its civilization has al-
ways remained stationary.

3d, The NEGRO. Characters. Black complexion; woolly hair; compressed cranium, and
flattish nose.

" It is very difficult to refer the Malays, or the Papuas, to any one of the three great va-
rieties of mankind already described. It'is a question"; however, whether the former people
can be accurately distinguished from their neighbours on either side: the Caucasian Hin-
doos on the one, and the Mongolian Chinese on the other.

" The Americans themselves have not yet been properly referred to either of the other
races, nor have they characters precise and constant enough to constitute a fourth variety.
Their copper-coloured complexion is not sufficient. The black lank hair, and scanty beard,
•would seem to approximate them to the Mongoles, if their well defined features, and pro-
minent noses, did not oppose such a classification; their languages are likewise as innume-
rable as their tribes, and no mutual analogy has yet been ascertained between them, nor
any affinity with the dialects of the ancient world.'' (Griffith.'' s Tran-s. of the Regne Jlni-
male.)

We are inclined to infer that America was peopled by the Mongoles from Asia; and that,
subsequently, it had been visited by Phoenician navigators: the greater part of whom set-
tled in it, particularly in Mexico; and that the imperfect navigation of that era prevented
many of the adventurers, if not all of them, from returning.

Of the Mortality of Females at the Change of Lift

, From the bills of mortality of both sexes, collected in Provence, Switzerland, Pans, Ber-
lin, Sweden, and Petersburgh, it would seem, 1st, that from 30 to 70, no other increase takes

tam vero descendentemsanguinem ex vena cava superiori phlogisticnm nee oxydatum in
abdomen atque extremitates inferiores perducere, quo fit, ut superiores corporis partes, ex-
ceptis pulmonibus, qui sanguinem ex vena cava superiori venientem venosum accipiunt,
primo graviditatis tempore magis vigeant polleantque. p. 215.

" Placenta oxygenium afferente, hepate carbonium submovente, quae functiones in adulto
in unopulmone conjunctae sunt." p. 216. (Joannis Mueller de Re spiratione Foetus Commcn-
tatio Physiologica, inAcademia L^russica Rhen,ana Prccmio Ornata. Lipsic. 1828. p. 159.

M. GeorTory-Saint-Hiolaire, proceeding on the principle, that there cannot be organiza-
tion without the combination of a nutritious fluid, nor yet assimilation without oxygenation
or previous respiration, endeavours to show: — 1st, That a respirable gas is present in the
amniotic fluid, as shown by the experiments of MM. Chevreuil and Lassaigne: 2d, That
the foetus, by means of its pores, as by so many tracheas, in the same manner as aquatic
insects, is enabled to consume the air contained in the surrounding fluid, owing to the air
being thus brought in contact with the venous blood which fills the capillaries of the skin ;
3d, That the contraction of the womb and of the abdominal muscles keeps up a certain de-
gree of pressure, which is as requisite to the perfect perforjnan"'1 of this process ?.s to th^
ordinary a^t of respiration -- 7?r'». Me?. Her. 1R23,

W APPENDIX.

place in the mortality oi females, than what naturally results from the progress of age; 2u,
that at all periods of the life of man, from 30 to 70, a greater mortality occurs than in wo-
men, but especially 40 to 50. (M. Bcnoiston de Vhateauneuf on the Mortality of Females
from 10 to 50 Years of Age. Paris, 1822.)

Of the Signs of Death.
Note M. M.

This subject has been so fully and ably discussed in the very excellent works of Dr. Beck,
of Dr. Gordon Smith, and of Dr. Paris and Mr. Foublanque, on Medical Jurisprudence, that
•we prefer recommending the reader to consult them on this subject, to entering imperfectly
upon the topic at this place, our limits not allowing the satisfactory discussion of it

93

CHAPTER. II.

Chemical constitution of the Solids and Fluids of the Human Body.

I. Simple substances entering into the Constitution of the different Animal Principles
or Constituents of the Human Body.

The following simple substances are variously combined, in order to produce the consti-
tuent parts of the body :

1. Azote, 6. Lime, 11. Magnesia, (Magnesium,}

2. Carbon, 7. Sulphur, 12. Silica,
li. Hydrogen, 8. Soda, (Sodium,) 13. Iron,

4. Oxygen, !>. Potass, (Potassium,) 14. Magnanese,

5. Phosphorus, 10. Muriatic Acid.

Of these, magnesia and silica may be considered as foreign bodies ; they being seldom
found, and in exceeding small quantities. The principal elementary ingredients are the
first six: animal substances may be considered as chiefly composed of them. The first four
constitute almost entirely the soft parts; and the other two form the basis of the hard parts.

II. Animal Constituents or Principles.

I. GELATIN consists of Carbon, 47.88 ; Hydrogen, 27.20; Oxygen, 27.20; Azote, 17.00;
or of 15, 14, 6, 2, atoms respectively. Contained in skin, bone, tendons, &c. Test,
Tannin.

II. ALBUMEN, — Corrosive sublimate detects gViTo Part tlie weight of the water contain-
ed in it. COMP.— Carbon, 52.883 ; oxygen, 23.872 ; hydrogen, 7.540 ; azote, 15.705, in
100 parts. Dr. Prout found it to consist of 15 atoms of carbon, 6 of oxygen, 14 hydrogen,
2 azote, according to the analysis quoted.

III. FIBRINE varies in its species in the different classes of animals. COMP. — Carbon,
53.360; oxygen, 19.685; hydrogen, 7.021; azote, 19.934. Consists of carb. 18 atoms, oxyg.
5, hydrog. 14, azote 3.

IV. COLOURING MATTER OF THE BLOOD. — Berzelius found it possessed of nearly the
same properties as fibrin. It is soluble in water at a low temperature; and in all the acids,
except the -muriatic, contains iron. (Berzelius, vol. 3. Med. Chirurg. Trans.)

V. UREA, or NEPHRIN, soluble in water and in alcohol. Precipitated in pearly crystals
by nitric acid and oxalic acid. Dissolved by a solution of potass or soda.

Oxygen,- - - 39.5) 2 atoms Hydrogen, - -0.25- - - 6.66

Azote, - - - 32.5 I 1 Carbon, - - 0.75 - - - 20.00

Carbon, - - -14.7(1 Oxygen, - -1.00- - -26.66

Hydrogen, - - 13.3 j 1 Azote, - - 1.75 - - - 46.66

100. 3.75 100.

(Dr. Prout.')

Gelatin is insoluble in cold water, albumen is insoluble in hot, and fibrine is insoluble in
both cold and hot.

The constituents of these three bodies, and of nephrin, according to the best analysis of
them hitherto made, are as follow :

Carbon. Oxygen. Hydrogen. Azote.
Gelatin, atoms 15 - - - - 6 - - - - 14 - - - - 2

Albumen, 17 - - - - 6 - - - - 13 - - - - 2

Fibrine, 18 - - - - 5 - - - - 14 - - - - 3

Nephrin, 1-- -1- -2----1

The colouring matter of the blood approaches albumen in many of its properties ; but it
seems entirely destitute of azote.

VI. Mucus. — Insoluble in water, transparent when evaporated to dryness, and, like
gum, soluble in the acids. Not soluble in alcohol or ether — does not coagulate by heat —
nor is precipitated by corrosive sublimate, or by galls. Is precipitated by the acetates of
lead, and by nit. argenti. Found in the epidermis, in nails, feathers, &c. (Bostock, in Ni-
cholson's Journ. XL 251.)

VII. OSMAZOMK is, probably, only an altered state of fibrine. Soluble in water and al-
cohol—does not gelatinize. Precipitated by nit. argenti. nit. hydrarg. and acet. and nit. of
lead.

VIII. PIGROMEL — found principally in bile ; resembles inspissated bile in its appear-
ance ; soluble in water and in alcohol :

APPENDIX,

5 atoms Carbon, - -

1 Hydrogen, -

3 Oxygen, • -

3.75 - - - 54.5S
1.25 - - - 1.82
3.000 - - - 43.65

(Dr. Thomson, An. Ph. 14. 69.)
IX. SUGAR OF MILK, according to Berzelius, consists of oxygen, 53.359 ; carbon ,
39.474 ; hydrogen, 7.167. (Annals of Philos. 5. 266.)

Dr. Thomson gives the table of the atomic analysis as follows :
4 atoms Oxygen, - - 4 - - - 48.4

5 Carbon, - - 3.75 - - - 45.4

4 Hydrogen, - 0.50 ... 6.2

8.25 100.0

X. OILS are fixed. — Fat — Cholesterine. — The former is composed of oxygen, hydrogen,
and carbon. The latter, according to Saussure, consists of 84.068 of carbon ; 12.672 of hy-
drogen ; and 3.914 of oxygen ; and differs little from the other fixed animal oils, excepting
that it contains more carbon and less oxygen than they.

XI. ACIDS. — The acids found constituting; and ready formed in animal bodies are the
following :

1. Phosphoric, 6. Uric, 11. Acetic.

2. Sulphuric, *7. Rosacic, 12. Malic,

3. Muriatic, 8. Amniotic, 13. Lactic,

4. Carbonic, 9. Oxalic, 14. Silica.

5. Bcnzoic, 10. Formic,

It may be remarked that the whole of the soft parts of animals consist chiefly of albu-
men, fibrine, and oils ; and the hard parts of phosphate of lime. The other animal princi-
ples are only in small quantities, and in particular textures. The oils seldom enter into the
structure of the organs of animals, they serve rather to lubricate the different parts, and to
fill up interstices.

III. Individual Textures and Fluids of the Human Body (formed of two or more oj
the foregoing Constituents.)

The Constituents of the BONES and TEETH of some of the Mammalia, according to the
Analyses 0/" BERZELIUS and other Chemists.

f •

SB«O

"** "

o

~

' *

*? \

» 5'?? ^

n o.

3*

2

c

8

p a * F

1"^

g

f

re

H^

Substances analyzed.

fffj

SP
2,5=

o
"-•J

1
o

s,

s

|l

3 " » ~

» o

1

r:
P

c'
§

1

Human bones recently dried,

33.3

1.2

11.3

51.4

2.0

1.16 j

Bullock's bones recently dried,

33.3

2.45

3.85

55.45

2.9

2.05

Osseous parts of human teeth,

28.0

1.4

5.3

61.95

2.1

1.25

Osseous parts of bullock's teeth

31.0

2.4

1.38

57.46

5.69

2.07

The enamel of human teeth,

2.0

—

8.0

85.3

3.2

1.5 j

The enamel of bullock's teeth,

3.56

1.4

7.1

81.0

4.2

3.0 j

The compact and cellular substances of human bones are, according to Berzelius, of the
same composition.

Forms the lateritious sediment in fevers, &c.

OF BONES AND TEETH, &

Substances submitted to

analysis.

0

I

1 Phosphate of mag-
nesia.

=

2,

a

1.
j Phosphate of lime.

1!

o

S

2,

to

r

Recent bullock's bones,

51.0

1.3

—

37.7

10.0

—

Vauque-
lin&Four-
croy.

A child's first teeth,

20.0

—

—

62.0

6.0

12

(6

i Teeth of an adult,

20.0

—

—

64.0

6.0

10

! The roots of the teeth,

28.0

—

—

5S.O

4.0

10

| The enamel of teeth,

—

—

—

78.0

6.0

16

j The spine, softened by disease,

79.75

0.82

4.7

13.6

1.13

—

Bostock j

Fourcroy and Vauquelin could not discover the fluate of calcium either in the enamel of
the teetli or in recent ivory.

Boiling water extracts slowly the cartilage of bone in the form of gelatine. Cold hydro-
chloric acid dissolves the salts which have lime for their base, leaving nearly altogether
untouched the whole of the cartilage. Ammonia precipitates the phosphate of lime from
its solution in warm hydrochloric acid : the phosphate of lime, however, thus obtained, is
accompanied with a considerable proportion of gelatine. Bones, submitted to dry distilla-
tion, give gelatine, and, as a residue the carbon of bones, which is a compound of animal
charcoal and the salts, with potash for their base: exposed to the air, the charcoal of bones
passes into the state of ashes.

Tophus, found in the articulations of the arm, consists of animal matter, with traces of
adipocire, 56.2 ; carbonate, phosphate, and hydrochlorate of potash, 3.2 : carbonate of
lime, with traces of the carbonate of magnesia, 12.5 ; phosphate of lime, 28.1. Another
specimen contained animal matter, with unctuous and fatty matter, and a little soda, 73.0 ;
carbonate of lime, 10 ; phosphate of lime, 17. (John Ecrits Chim. v. 104.)

The concretions found in persons subject to the gout are composed of the urate of am-
monia. (Wallaston.)

The marrow of bones. The medulla of the cylindrical bones of the bullock contain
membranes and vessels, 1 ; fat, 96 ; a reddish serum, 3.

The medulla of the lower part of the radius, and of the tibia, contains a very liquid fat,
and neither coloured vessels nor membranes.

The diploe of the extremities of the long bones contain fatty matter and a reddish se-
fum, in very variable proportions.

The rertebras of the dorsal column contain a deep brown serum, partly concrete, soluble
in water, and rarely a trace of fat. (Bcrzelius, JVbuv. Journ. de Gehl. ii. 287.)

The. cartilages dissolve in water kept for a considerable time at the boiling point, and
form a gelly.

The SYNOVIA of the human subject consists of, a yellowish fat, albumen, which consti-
tutes its chief ingredient, an uncoagulable animal matter, soda, chlorate of potassium and
of sodium ; and the ashes furnish carbonate and phosphate of lime. (Lassaigne and Bois-
sel, Journ. de Pharm. viii. 306.)

The synovia of the articulations of the knees of a man was found to consist of a floccu-
lent substance, which coagulated at the temperature of boiling water, and was precipitated
by the chlorate of mercury. (Bostock.}

Qout appears to change, in some degree, the secretion in the joints affected. Dr. Wol-
laston, Dr. Pearson, and Mr. Tennant, found the chalk stones formed in this disease com-
posed of urate of soda. Fourcroy has confirmed this analysis ; he therefore conjectures
that synovia contains uric acid. (Four. ix. 224.)

Synovia of a horse. — A. From an articulation which was in a healthy state : soluble al-
bumen 6.4 ; animal matter, which did not become concreate, with the carbonate and the
hydrochlorate of soda, O.G ; phosphate of lime, 0.15 ; traces of an ammonial salt, and of
phosphate of soda ; water 9.23. — B. From a joint ar.chylosed in consequence of a wound \

^5 APPENDIX.

insoluble, fibrous albumen ; soluble albumen ; free phosphoric acid ; the same salts as men*
tioned above. (John Ecrits Chim. vi. 146.)

Synovia of an elephant: reddish, filmentous, of a slightly saline and insipid taste ; when
warmed or heated by mineral acids it coagulated. It contained a soluble albumen of ani-
mal matter precipitated by tannin, and which did not become concrete, in a small quanti-
ty ; soda and hydrochlorate of potash. ( Vauquclin, Ann. de Chim. et de Phys. vi. 399.)

The periosteum approaches the chemical properties of cartilage, and yields a small pro-
portion of gelatine.

The ligaments resist for a very long time the action of boiling water, but dissolve at
last, in part, fike gelatine;

The membranes, as the serous (the pia^mater, arachnoid, pericardium, pleura, peritone-
um, &c.) and the skin, dissolve in boiling water, and pass to the state of gelatine.

INTEGUMENT, Cutis vera — formed of fibres interwoven like a felt. It yields little gela-
tin, on maceration in cold water : by long boiling in water it becomes gelatinous, and dis-
solves completely, and by evaporation it becomes glue. Hence it appears to be a peculiar
modification of gelatin. By tannin, and the extractive of oak bark combining with it, lea-
ther is formed.

Rete mucosum — " is a mucous membrane, situated between the cutis vera and the epi-
dermis. The black colour of negroes is said to depend upon a black pigment situated in
this substance ; but it seems to us to be situated in the inner or flocculent surface of the
epidermis. Chlorine deprives it of its black colour, and renders it yellow. A negro, by
keeping his foot for some time in water impregnated with that gas, deprived it of its colour,
and rendered it nearly white ; but in a few days the black colour returned again with its
former intensity. (Fonrcroy, ix. p. 259.) This experiment was first made by Dr. Beddoes
on the fingers of a negro." (Beddoes on Factitious Airs, p. 45.)

The epidermis possesses the same properties as horn. The internal surface of the epi-
ilermis seems- to be the seat of the black colour of the negro, and not the rete mucosum.
The human epidermis consists of — fatty matter, 0.5 ; animal matter soluble in water, 5.0 ;
concrete albumen, 93 to 95 ; lactic acid, lactate, phosphate, and hydrochlorate of potash,
sulphate, and phosphate of lime, an ammonical salt, and traces of iron, 1. (John Ecrits
Chim. vi. 92.) The nails of the fingers and toes present an analogous constitution.

HUMAN HAIR may be regarded as fine tubes of a substance similar in all its properties
to horn, covered by a white adipocire, (probably furnished by the sebaceous glands of the
scalp) and filled with an oily matter, which is either of a greenish black colour, red, yel-
low, or nearly colourless, according as the hair is black, red, yellow, or white. The ashes
of human hair is composed of the hydrochlorate of soda ; of the carbonate, sulphate, and
phosphate of lime, (and the phosphate of magnesia in that which is white) a considerable
portion of silicia, oxide of iron in a very marked proportion in black hair, but scarcely to
be recognised in that which is white; and a very small quantity of the oxide of manganese.

The sulphur, which is undoubtedly combined in the organization of the corneous or horny
substance, is found more abundantly in the red and light coloured hair, than in the black.

The MUSCULAR FLESH. The muscular substance is probably composed of very little
more than fibrine, traversed by cellular tissue containing fat, by the aponeuroses and ten-
dons, by vessels containing blood, by lymphatics containing lymph, and by nerves. It is,
however, very probable that osmazome, lactic acid, the hydrochlorate and phosphate of
soda, and the phosphate of lime, particularly belong to muscular flesh, although they are
also found in the blood. Cold water extracts of the muscular substances the red colouring
matter of the blood, the albumen, the osmazome, and the salts of the blood : boiling water
takes up the cellular tissue reduced to gelatine, and the fat which swims on its surface; the
residuum consists of fibrine, a little altered by the boiling, and which yields the phosphate
of lime by incineration. The muscular substance of beef gives, by incineration, more lime
than that of veal. ( Hatchett. )

According to Berzelius, the muscular texture contains: fibrine, vessels, and nerves, 15.S;
cellular substance, 1.9 ; albumen, 2.2 ; osmazome, with the lactate and hydrochlorate of
soda, 1.8 ; mucous matter, 0.15 ; phosphate of soda, 0.9 ; phosphate of lime, containing a
portion of albumen, 0.08 ; water and loss, 77.17.

Bullock's heart. Osmazome, 7.57; albumen and cruor, 2.76; fibrine with vessels, nerves,
cellular tissue, fat, and phosphate of lime, 18.19 ; an ammonical salt and a free acid in an
indeterminate quantity ; lactate of potash, 0.19 ; phosphate of potash, 0.15 ; c.hloruret of
potassium, 0.12 ; water, 77.04. (Bracounot Jinn de Chim. et de Phys. xvii. 388.)

An ossification found in the human heart. It contained a cartilaginous matter and phos-
phate of lime in nearly equal proportions, with a little carbonate of lime. (John Ecrits
Chim. 5. 159.)

An ossification found in the veins of the human uterus: membranous substance and phos-
phate of lime, in nearly equal quantities, with a little of the carbonate of lime and traces
of the hydrochlorates. (John, ibid. v. 126.)

OF BONES AND TEETH, fcc. ^7

BRAIN and NERVES. The hemispheres of the human brain : a reddish-brown liquid fat,
leaving phosphoric acid by combination, 0.7 ; a white fat becoming blacker by fusion, and
giving rise to much phosphoric acid by combustion, 4.53 ; phosphorus contained in these
fatty substances, 1.5 ; osmazome, 1.12 ; albumen, 7.0 ; phosphate of potash, muriate of
soda, phosphate of lime and phosphate of magnesia, 5.15 ; water, 80.

The human cerebellum gave the same results.

Medulla oblongata and spinal cord have the same constituent principles, but they con-
tain more of the fatty matter, and less albumen, osmazome, and water.

The nerves of the human subject contain less of the liquid and chrystallizable kinds of
fatty matter, but more of the fatty substances which resembles adipocire, and much more
albumen than the brain. (Vauquelin, Ann de Chim. Ixxxi. 37.)

The grey substance of the brain of a calf : albumen insoHible in water, 10.0 ; an unctu-
ous incrystallizable fat, osmazome, phosphate of ammonia, phosphate of soda, phosphate
of lime, phosphate of magnesia, hydrochlorate of soda and traces of iron, 15.0 to 10.0 ; wa-
ter 75 to 80.

The white substance of the brain of a calf contained more fatty matter than the grey ; it
presented traces of silicia. The cerebellum of the calf gave the same products as the cineri-
tious substance.

The optic thalami, the medulla oblongata, spinal marrow, and the nerves of the calf,
gave results similar to those furnished by the white substance of the brain, excepting that
they contained more albumen and less water.

* The brain of a bullock contained also phosphate of ammonia, a more solid albumen, a
reddish coloured fat, and a chrystallizable fat. The composition of the brain of the stag
was similar. (John Ecrits Chim. iv. 249. v. 162.)

The lymph found in the ventricles of the human brain: gelatine (osmazome ?) 0.9 ; mu-
cus (salivary matter ?) 0.3 ; albumen, 0.6 ; hydrochlorate of soda and a little of the phos-
phate of soda, 1.5 ; water, 96.5 ; loss, 0.2. (Haldat, Ann. de Chim. ex. 176.) .

A soft concretion found incysted in the cerebral pulp of a subject who was afflicted with
mental alienation : white grease^6 ; semiconcrete albumen, 17.0 ; cartilaginous substance,
insoluble in potash, 18.0 ; salts with ammonia, potash, soda, and lime for their base, about
2.0 ; water, 57. (John Scrits Chim. v. 102.)

See the note at p. 207 and 208, for the composition of the * humours and textures of the
eye.' The pigmentum nigrum is mixed with mucus.

Mucus. The nasal mucus of the human subject contains : — mucus, 5.33 ; albumen, and
salivary matter with a trace of phosphate of soda, 0.35 ; osmazome, with lactate of soda,
0.3 ; soda, 0.09 ; hydrochlorate of potash and of soda, 0.56 ; water, 93.37. (Berzelius,
Fourcroy and Vauquelin.) The mucus of the trachea, according to Berzelius, is similar
in its consumption.

SALIVA. Has a strong affinity for oxygen, absorbs it readily from the air, and gives it
out again to other bodies. The human saliva consists of — salivary matter, 0.29 ; mucus,
0.14 ; osmazome with lactate of soda, 0.08 ; soda, 0.02 ; hydrochlorate of potash, and hy-
drochlorate of soda, 0 17 ; water, 99.29. (Berzelius, Bostock, Thomson, John.)

Salivary calculi are formed of a membranous substance, containing phosphate of lime.

The tartar of the teeth. Mucus, 1.25 ; salivary matter, 1.0 ; animal matter, soluble in
hydrochlorate acid, 7.5 ; phosphate of lime, and phosphate of magnesia, 7.90. (Berzelius.)

The LACHRYMAL. FLUID. Animal matter, soda hydrochlorate and phosphate of soda,
and phosphate of lime, 1.0 ; water, 99.0. The calculi of the lachrymal gland are formed,
of the phosphate of lime. ( Vauf>u

The GASTRIC JUICE. The gastric juice ejected by vomiting after fasting for some time
resembled, according to Montegre, in appearance, the saliva ; it contained flocculi of mu-
cus, and underwent putrefaction as rapidly as the saliva ; but sometimes it was acid, and
then it did not undergo putrefaction.

LYMPH : the liquor found in the thoracic duct of animals which have not taken nourish-
ment for 24 hours, is as limpid as water, does not affect the vegetable colours, does not co-
agulate either by heat or by acids ; it becomes slightly turbid from alcohol, leaves a very
small residuum when submitted to evaporation, and consequently appears to contain but*
very little matter, and only a small quantity of the hydrochlorate of soda.

The lymph of a horse taken from the thoracic duct towards the inguinal region and me-
^ocolon, was of a greenish yellow, translucid, and concreted in 12 minutes into a clear ge-
latine ; the coagulum, which hardly amounted to pj-g-, was similar to fibrine, the fluid con-
tained about 0.04 of albumen, muriate of soda, with a little soda and phosphate of soda.
(Reuss andEmmert, Journ. de Scherer, v. 681.)

CHYLE. The chyle taken from the thoracic duct of a dog, three hours after a vegetable

diet, resembled clear milk, and deposited a reddish-white coagulum : this coagulum, which

had the appearance of fibrine, was to the serum at first in the proportion of 48 to 100 ; but

^eing left longer to itself it increased considerably. The specific weight of the serum

98 APPENDIX.

was 1.018 ; it did not coagulate at the temperature of boiling water, but became turbid \
after some weeks it became a little sour, without undergoing putrefaction : in 100 parts it
contained from 4.8 to 7.3 of solid matter, which consisted of 0.9 of soluble albumen and
salts ; it contained neither gelatine, nor phosphate of lime, nor any ammoniacal salt.

The chyle of a dog, collected three hours after having eaten meat, had the appearance
of cream : its coagulum, a little red, was to the serum at first as 46.5 to 100, but this quan-
tity diminished gradually: the serum became much more turbid by heat and by the addition
of acids than that produced from vegetable food ; it underwent putrefaction in three days ;
it deposited when allowed to stand, a white and greasy cream, and furnished from 7 to 9.5
per cent, of solid matter consisting of soluble albumen, without any gelatine. Brande ob-
served a substance analogous to the sugar of milk in the serum. (Marcet, Vauquclin,
Brande , $r.)

Chyle, " when drawn from the thoracic duct, about five hours after the animal has ta-
ken food, is an opaque liquid of a white colour ; without smell, and having a slightly acid
taste, accompanied by a perceptible sweetness. The presence of a free alkali is indica-
ted. About ten minutes after it is drawn from the animal it coagulates into a stiff jelly,
which in the course of twenty-four hours gradually separates into two parts, producing a
firm contracted coagulum, surrounded by a colourless fluid."

1st. " The coagulum, as appears from the experiments of Vauquelin, (Ann. de Chim.
81 ; 113,) is an intermediate substance between albumen and fibrine. He considers it al-
bumen on its way to assume the nature of fibrine. It is not so stiff, nor of so fibrous a tex-
ture as fibrine ; it is more easily acted on and dissolved by 'caustic alkalies. It is insoluble
in alcohol and ether, readily dissolved by diluted sulphuric acid, very dilute ; nitric acid
converts it into adipocire. When burnt it leaves a charcoal, containing common salt, phos-
phate of lime, and gives traces of iron." (Thomson.)

2d. The liquid portion separates albumen on boiling, and contains sugar and a very small
portion of a fatty matter, similar to that found in the brain. The same salts as in other ani-
mal fluids.

BJ.OOD. Taste slightly saline, smell peculiar, specific gravity 1.0527. As soon as the vi-
tal influence of the vessels ceases to act on the blood, it separates into the coagulum or
cruor, and serum. The common proportion is one part of cruor to three of serum. The
proportion, however, varies from 1.2 and 1.4. If the separation of fibrine, giving rise to
the coagulation, takes place in repose, the fibrine entangles the red particles of the blood j
but if the blood be kept in motion, the red particles escape into the serum, and the fibrine
is separated into threads.

1st. Serum. Possesses the taste and smell of the blood, specific gravity is about 1.0287.

Berzelius found that the serum of human blood was composed as follows: — water, 905.00,
albumen, 80.00 ; muriates of potash and soda, 6.00 ; lactate of soda, with animal matter,
4.00 ; soda, phosphate of soda, with animal matter, 4.10 ; loss, 0.90 ; — 1000.00. (Annals
of Philosophy, ii. 202.)

"Dr. Marcet found the constituents of serum as follows :— water, 900.00 ; albumen
86 80 ; muriates of potash and soda, 6.60 ; muco-extractive matter, 4.J00 ; sub-carbonate of
soda, 1.65 ; sulphate of potash, 0.35 ; earthy phosphates, 0.60.— 1000. (Medico. Chirurg
Soc. Transact, ii. 376.)

" The muco-extractive matter was doubtless impure lactate of soda." " Berzelius is ot
opinion, that the sulphate of potash, and the earthy phosphates which were found by Dr.
Marcet in the ashes of serum, were formed during the incineration. For phosphorus, sul-
phur, and the basis of lime and magnesia, exist according to him as constituents of albu-
men."

" Gelatin was considered as a constituent of serum, until Dr. Bostock and Professor Ber-
zelius have sho\vn, that the opinion of its existence in blood is not well founded."

2. The cruor, or the clot. Specific gravity about 1.245. Is separated into two portions
by ablution in water. 1st, A white, solid, elastic substance, which has all the properties
of fibrine. 2d, The portion held in solution by the water is the colouring matter, with a
portion of serum.

• "Berzelius and Brande have shown, that this clot is a compound of fibrine, albumen,,
and colouring matter of blood. According to the analysis of Berzelius, it consists of — co-
louring matter, 64 ; fibrine and albumen. 36 ; — 100.

" When the colouring matter is incinerated, about one-third of a per cent, of oxide of
iron may be extracted from its ashes. This portion of iron is a constituent of the colouring
matter, and perhaps the cause of its red colour. (Thorn, iv. 492.) But in what way it is
united to the albuminous portion of the colouring matter remains unknown. When incine-
rated, the colouring matter leaves 7V^ of its weight of ashes, consisting according to the
analysis of Berzelius, (which appears to be the most to be depended on,) of the following
ingredients : — oxide of iron, 50.0 ; sub-phosphate of iron, 7.5 ; phosphate of lime with tra-
ces o.f magnesia, frO ; pure lime, 200 ; carbonic acid and loss. 16,5 — 100.0. »

OF BONES AND TEETH, kc.

Berzelius is of opinion that none of those bodie^ existed in the collouring matter ; but.
merely their basis, iron, phosphorus, calcium, &c., And that they aie formed during the
incineration.

" The albumen of blood leaves the same quantity of ashes as the colouring matter. But
these ashes contain no traces of iron."

" Dr. Gordon has rendered it probable, that during the coagulation of blood a little heat
is evolved." (Annals of Philosophy, iv. 139.)

Rouelle has obtained nearly the same ingredients, only in different proportions, from the
blood of a great variety of animals.

F&tal blood. " Fourcroy made some experiments on the blood of the foetus. He found
that it differed from the blood of the adult in three things. 1st, Its colouring matter is
darker, and seems to be more abundant. 2d, It contains no fibrine, but probably a greater
proportion of gelatin (?) than blood of adults. 3d, It contains no phosphoric acid. — Four.
Jinn, de Chim. vii. p. 162.

Diseased blood. 1st. " Deyeux and,> Parmentier (Journ. de Phys. xliv. 454,) ascertained
thtit the buffy coat consists of the fibrine. The cruor, deprived of this substance, is much
.sotteetbari usual, and almost totally soluble in water.

2. " The blood drawn from several patients labouring under sea scurvy, affording scarce-
ly any remarkable properties to these chemists, except a peculiar smell, and an albumen
which was not so easily coagulated as usual."

3. The blood of patients in putrid fevers gave no sensible alteration in its properties to
the examinations of these chemists.

4. " The blood of diabetic patients; the serum of the blood, according to the experiments
of Dobson and Hollo, assumes the appearance of whey. Dr. Wollaston has shown, that it
contains no perceptible quantity of sugar, even when the urine is loaded with it."

MILK separates into cream, "curd and whey. 1st, Cream is composed of a peculiar oil,
curd, and serum. Cream of the specific gravity of 1.0244, was analysed by Berzelius, who
found it composed of — butter, 4.5; cheese, 3.5 ; whey, 92.0. — 100.0.

2d, Curd may be precipitated by rennet, or the acids, alkalies dissolve it easily. The
constituents of curd, according to the analysis of Gay Lusac and Theuard, are as follows: —

Carbon 59.781

Oxygen 11.409

Hydrogen 7.429

Azote 21,381—100.000

Dr. Thomson's application of this analysis to the atomic theory.
7 atoms Carbon 5.25 .60.87 C By doubling the number J 14 atoms Carbon

1 atom Oxygen 1.00 11.60 j of atoms, it may be com- f 5 Oxygen

5 Hydro' 0.625 7.24 ") pared with gelatin, albu- ("10 Hydrog.

1 Azote 1.75 20.29 f men, and fibrine. 3 2 Azote

8.625 100.00 28 17.25

Proust has found in cheese an acid, which he calls the cascic acid, to which he ascribes
several of the peculiar properties of cheese. (Journ. de Phys. Ixiv. 107.)

The coagulation of curd probably depends upon the same cause as that of albumen.

3. Whey still possesses some curd ; on evaporation it deposits crystals of sugar of milk.
Towards the end of the evaporation, some crystals of muriate of potash, and of /nuriate of
soda, make their appearance. (Parmentier Journ. de Phys. xxxviii. 417.) According to
Scheele, it contains also a little phosphat of lime. (Scheele, ii. 61.) Fourcroy and Vau-
quelin, Thenard, Bouillon, la Grange, and Berzelius, have analyzed whey. The latter
chemist gives the following as the ingredients of milk deprived of its cream: —

Water 928.75

Curd with a little cream .... 28.00

Sugar of milk 85.00 *

Muriate of potash 1.70

Phosphate of potash 0.25 Milk may be made to ailbrd a liquor re-
Lactic acid, acetate of potash, with ) g 0~ sembling wine or beer, from which alcohol

a trace of lactate of iron ) mav be separated by distillation. The Tar-
Earthy phosphates - 0.30 tars obtained all their spirituous liquors from

mare's milk.

1000.00

It has been ascertained, that milk is incapable of being converted into wine, till it has
become sour; after this, nothing is necessary but to place it in the proper temperature; the
fermentatioft begins of its own accord, and continues till the formation of wine be comple-
ted. (Parmentier, Journ. de Phys. 38. 365.) A great quantity of carbonic acid is extrica-
ted during the fermentation of milk. (Scheele, ii. 66.) Milk is fermented and kept for
many months, or even years, in the Orkney and Shetland Islands; but, along with a small
portion of alcohol which i* formed, the acidity is inconsiderable.

100 APPENDIX.

'The ingredients of the milk of most animals are nearly the same, the proportion only
differs.

The human milk differs from cow's milk 1st, in containing a much smaller quantity of
curd. 2d, Its oil is so intimately combined with its curd, that it does not yield butter. 3d,
It contains rather more sugar of milk.

Parmentier and Deyeux ascertained, that the quantity of curd in woman's milk increases
in proportion to the time after delivery. (Journ. de Phys. 38. 422.)

None of the methods by which cow's milk is coagulated, succeed in producing the coa-
gulation of the human milk. (Clarke Irish Trans, vol. ii. p. 175.)

BiirE (human.) The following is the analysis of bile, according to Berzelius: — water,
908.4; picromel, 80.0; albumen, 3.0; soda, 4.1; phosphate of lime, 0.1; common salt, 3.4;
phosphate of soda, with some lime, 1.0. — 1000.

Biliary calculi are formed either entirely of cholesterine; or they also contain a yellow
concrete mucous, picromel, and rarely phosphate of lime or carbonate of lime. These lat-
ter ingredients frequently almost entirely replace the cholesterine. ( Gren. Orfila )

CERUMEN OF TH • EAR. Vauquelin considers it composed of the following substances.
1st, Albumen. 2d, An inspissated oil. 3d, A colouring matter. 4th, Soda. 5th, Phos-
phate of lime. (Fourcroy, ix. 373.)

TEARS. According to the analysis of Fourcroy and Vauquelin (Jourh. de Phys. vol.
xxxix. p. 236,) they are composed of the following ingredients: — 1st, Water. 2d, Mucus.
3d, Muriate of soda. 4th, Soda. 5th, Phosphate of lime. 6th, Phosphate of soda.

" The saline parts amount only to about 0.01 of the whole. The mucus contained in the
tears has the property of absorbing oxygen gradually from the atmosphere, and of becoming
thick and viscid, and of a yellow colour. This property of acquiring new qualities from
the absorption of oxygen, explains the changes which take place in tears in some diseases
of the eye."

SWEAT contains salivary mucus; osmazome; lactic acid; lactate of soda; and hydro-
chlorate of potass and soda. (Berzelius.)

Thenard found it composed of an animal substance analagous to gelatine ; acetic acid ;
hydrochlorate of soda; phosphate of lime; phosphate of iron, and water.

URINE. The human urine, in a state of health, has a specific gravity of 1.02. It con-
tains urea, 3.01; a matter analagous to saliva, osmazome, lactic acid, lactate of ammonia,
and a little urea, 1.724; mucus, 0.032; uric acid, 0.10; phosphate of ammonia, 0.150; sul-
phate of potassa, 0.371; sulphate of soda, 0.316; hydrochlorate of soda, 0.445; phosphate of
soda, 0.294; phosphate of lime, with a little phosphate of magnesia, and a trace of the fluate
of calcium, 0.1 ; silica, 0.003; water, 93.3. (Berzelius.)

Besides the constituents of healthy urine, as determined by Berzelius, the following have
been occasionally detected in it; albumen; resin with ulmine; acetic acid; benzoic acid (in
infants;) carbonic acid; sulphur; chloruret of potassium; and iron.

Urine which is excreted in the morning, generally contains more of the saline and solid
ingredients. Uric acid abounds most in the urine of individuals who live on animal diet.
Urine absorbs oxygen from the atmosphere, and passes into a state of putrid fermentation.
This is more or less rapid according to the elevation of the temperature; and the quantity
of mucus and albumen present in the urine is considerable.

The urine in diabetes niellitus has a specific gravity of from 1.026 to 1.05. It generally
contains no urea — sometimes a minute quantity of it. It is remarkable for its quantity, and
for the saccharine matter which it holds in solution; the saline ingredients are generally pre*
sent, but in smaller proportions. As the quantity of sugar diminishes, that of albumen in-
creases, and this latter is replaced, as the disease disappears, by urea and uric acid. The
chief difference between this urine and that secreted in diabetes insipidus, consists in the
absence of saccharine matter from the latter.

Icteric urine is frequently yellow and bitter, and contains the principles of bile.
In acute dropsy the urine is generally charged with albumen. When dropsy results from
disease of the liver, the urine is brown, and deposits a brown sediment.
• SEMEN, when ejected, is the product of two different glands, the one fluid and milky,
supposed to be secreted by the prostate gland; the other a thick mucilaginous substance,
considered to be secreted by the testes, and in which numerous white shining filaments may
be discovered: it has a slightly disagreeable odour, an acrid irritating taste, and is of a great-
er specific gravity than water. As this liquid cools, the mucilaginous parts become trans-
parent, and acquire a greater consistency, but in about, twenty minutes after its emission,
the whole becomes perfectly liquid.

This change supervenes without any absorption of moisture from the air, and without its
action, taking place equally in close vessels. Semen is insoluble in water before this spon-
taneous liquefaction, but readily so afterwards. (Vauquelin, Jinn, de Chim. ix. 70.) When
semen is kept in a moist air, at about 77°, it acquires a yellow colour, like the yolk of an
egg; it exhales the odour of putrid fish, and its surface is covered by the byssus septica.

OF BONKS AND TEETH, &c.

According to Vauquelin semen is composed of water, 90; mucilage, 6; phosphate of lime,

3; soda, l.= 100.

The OVA. from the ovaria of the human subject : gelatine, albumen, phosphate, with an

alkaline base in excess. (John's Chemical Writings, vi. 158.)

AMNJOTIC FLUID, which surrounds the foetus, in the human species is of a slightly milky
lour, owing to a curdy matter suspended in it, of a weak pleasant odour, and saltish
<te; specific gravity 1.005; is composed of about water, 98.8; albumen, muriate of soda,

colour
tast

<oda, phosphate of lime, lime, 1.2 = 100.0. (Vauquelin and Buniva, Jinn, de Chim.
xxxiii. 270. 274.) A curdy-like matter is deposited on the surface of the foetus, evidently
from the liquor of the amnios. Vauquelin and Buniva have shown that it is different from
any thing contained in this fluid ; that it has in its chemical relations a great resemblance
to fat. They conjecture that it is formed from the albumen of this liquid, which has un-
dergone some unknown changes. It appears to be of service in preserving the skin of
the foetus from being acted of by the liquor of the amnios, and to facilitate its passage hi
parturition.

Pus. Its taste is insipid, and it has no smell when cold. Before the microscope it exhi-
bits the appearance of white globules swimming in a transparent fluid, specific gravity
from 1.031 to 1.033. When incinerated, the ashes give traces of iron. (Gren's Hand-
buck, ii. 426.) It produces no change on vegetable blues. Alcohol thickens pus, but does
not dissolve it ; nor does it unite with oils. Soluble in sulphuric acid, but separated on the
addition of water. The same is the case with nitric acid. Muriatic acid also dissolves it
when heated, and it is again separated by water.

The fixed alkaline leys form with it a whitish ropy fluid, which is decomposed by water,
the pus being precipitated. Corrosive sublimate, nitrate of mercury, and nitrate of silver,
give a whitish precipitate from its solution, indicating an analogy with albumen.

Expectorated matter yields traces of sulphur, and perhaps also of phosphorus; and it con-
tains the following saline substances: — 1st, Muriate of soda, varying from H to 2^ in the
1000 of expectorated matter 2d, Phosphate of lime, half a part in the 1000. 3d, Ammo-
nia united probably to phosphoric acid. 4th, A phosphate probably of magnesia. 5th, Car-
bonate of lime. 6th, A sulphate. 7th, Vitrifiable matter, probably silica. 8th, Oxide of
iron. The whole of these last six substances scarcely amount to one part in the 1000 of
expectorated matter.

The proportion of saline matter of albumen present in expectorated matter varies much,
in different circumstances. The thicker it is, in general the smaller is the quantity of the
«aHne matter: whereas, when very thin, it is often impregnated with salts, especially with
the muriate of soda to a great degree, and tastes distinctly salt and hot.

Liquor of the pericardium. Dr. Bostock (Nicholson's Journ. xiv. 147.) considers it to
be composed of — water, 92.0; albumen, 5.5; mucus, 2.0; muriate of soda, 0.5 — 100.0.

Liquor of dropsy. Dr. Bostock found the liquid formed in " spina bifida" to be com-
posed as follows: — water, 97.8; muriate of soda, 1.0; albumen, 0.5; mucus, 0.5. gelatin,
0 2; lime, a trace. (Nichol. Journ. xiv. 145.)

The same kind of fluid obtained from the head of a child of ten years was examined by
Dr. Prout. It faintly reddened litmus paper. Its constituents were as follow: — water, 987.
18; albumen, precipitated by nitric acid and heat, 1.66; substances soluble in alcohol (fatty
adipocirous matter, lactate of soda,) 1.65; substances soluble in water — 9.51. viz. muriates
of potash and soda, 6.80; sulphate of soda and some animal matter not coagulated by
heat, 2.71— 1000.00. (Ann. of Phil. xvi. 151.)

Liquor of blisters. The analysis of Macqueron (Ann. de Chim. xiv. 225.) gives it nearly
the same constituents as the serum of the blood : from 200 parts he obtained — albumen,
36 -, muriate of soda, 4; carbonate of soda, 2; phosphate of lime, 2; water, 156 — 200.

HUMAN FJECES. Their colour seems to depend upon the bile mixed with the food in the
digestive canal; when too light it is supposed to denote a deficiency of bile; when too dark,
there is supposed to be a redundancy of that secretion. The following table shows the an-
alysis of BERZELIUS. (Gehlin's Journ. vi. 536.)

Water 73.3'

Vegetable and animal remains - - 7.0

Bile 0.9

Albumen 0.9

Peculiar and extractive matter sup- ^

posed to be formed from picro-> 2.7
mel. \

Salts* 2.3

Slimy matter, consisting of picromel,

peculiar animal matter, and inso- J 14.0
luble residue.

100.0

* The SALTS, their relative proportions.
Carbonate of soda - - - - 35
Muriate of soda .... 4
Sulphate of soda - 2

Amm. phosphate of magnesia, - 2

Phosphate of lime. . - - 4

102

APPENDIX.

GASES EXISTING IN THE IXTESTIVAL c AX A.L. These may be ascribed to three sources:
—1st, from the common air swallowed with the food ; 2d, from the decomposition of the
intestinal contents; and 3d, from the occasional secretion of gas from the mucus surface of
the tube.

The gases from the first source are found chiefly in' the superior portions of the canal;
those from the second source in the lower part, and those from the third, are by no means
limited in their situation. It is reasonable to suppose that a large proportion of the azote
and carbonic acid is derived from this last source.

From the experiment of Magendie and Chevrule, who examined very soon after death
the gaseous contents of the stomach and intestines of four criminals executed at Paris, the
following appear to be the proportions and the relative quantities in the different portions
of the canal.

1. Gases in the Stomach.
Oxygen* ....
Carbonic acid -
Hydrogen ...

Azote -

11.00

14.00

3.55

71.45

100.00

2. Ga$£s in the small Intestines.^
Oxygen w 00.00 - - 00.00 - - 00.0
Carbonic acid 24.39 - - 40.00 - - 25.0
Hydrogen 55.53 - - 51.15 - - 8.4
Azote 20,08 - - 8.85 - - 66.6

100.00

100.00

100.0

3. Gases in the large Intestines.

Carbonic acid - - - - - 43.50 -

Hydrogen and carburetted hydrogen 54.7

Azote

4. Gases in the Caecum.
Carbonic acid - - - ... 12.5
Hydrogen - - - - - 7.5
Carburetted hydrogen - - 12.5
Azote 67.5

100.0

70.0
11.6

51.03=100.00 18.4=100.0

5. Gases in the Rectum.
Carbonic acid -
Carburetted hydrogen •
Azote ---

(4>m. de Chim. et Phys. ii. 492.)

42.86
11.18
45.96

V

100.00

* The oxygen seems to be absorbed by the blood before it reaches the small iniestiiies-
t Results in the different individuals.

FINIS.

ANALYTICAL INDEX.

PREFACE.— Preliminary discourse. Physiology—the Science of Life,
Definition of Life, 2, 3.

§ I. Of Natural Beings, 9.

They are inorganic or organized. — The former are simple or complex;
the latter always complex, and distinguished into vegetable and animal*
Reciprocal dependence of all these berhgs, 9.

§11. Of the Elements of Bodies, 9.

The Elements of Bodies. Their number forty-four 5 but it is probable
that several appear to us simple, from the imperfection of our means of
analysis, 10.

§ III. Differences between Organized and Inorganized Bodies, 1 1.

i

Differences between organized and inorganized bodies, 11. Homoge-
neousness of the latter ; complex nature of the former ; necessary co-ex-
istence of fluids and solids in all organized and living beings, simplicity
of inanimate matter : complex nature and tendency to decomposition of
organized bodies, 12, 13, 14.

§ IV. Differences Between Vegetables and Animals, 14.

Differences between animals and plants, 14. The great distance be-
tween the mineral and vegetable kingdom. A considerable approxi-
mation, on the contrary, between animals and plants, 15. Of all the
characters which mark the differences between these substances, the
most remarkable is the presence of an alimentary tube, which is found in
every animal from man down to the polypus, 15. In all animals, nutri-
tion is performed by two surfaces, especially by the internal ; the alimen-
tary canal is the most essential part of their body, 16. It retains life
longer than any other part— Experiments disproving Haller's opinion on
this subject, 16.

§V. Of Life, 16.

Consists of a number of phenomena proportioned to the complication
of the organization, 17, Simple in plants, in xvhich its actions are limit-

104

ed to nutrition and reproduction, 17. Of Life in the polypus; this ani-
mal, consisting merely of a sentient and contractile pulp, shaped iiito an
alimentary cavity, 18. Of life in worms, 18— in crustaceous animals, its
apparatus more perfect, 19. Of life in cold-blooded animals, 19. In
warm-blooded animals and in man, 20. General view of the human or-
ganization, 20, 21. Of the elementary fibre, 23. Dependence of life
on the oxydation of the blood in the lungs, and on the distribution of
this vivified blood throughout the organs, 23.

§ VI. Of tils Vital Pro/icrfiee ; Sensibility and Contractility, 23.

These two properties not possessed, in an equal degree, by all living
bodies, 23. Modifications of sensibility in different organs, 27. Obser-
vations on the contractility of serous membranes, 27. Caloricity, 29.
Laws of sensibility, 30. Influence of sieep, of climates, of the seasons,,
of the age, &c. on the vital properties, 32, 33, 34.

* § VII. Of Sympathies, 34.

Of sympathy, 34. Diseases arising from association ; Synergies, 355
36, 37.

§ VIII. Of Habit, 33.

Of habit, 38. It uniformly Jessens physical sensibility — A curious
fact showing the effects of habit, 39. Habit impairs the sensitive power
but improves the judgment, 41.

§ IX. Of the Vital Principle, 42.

•

The vital principle, not a being existing by itself, and independently
of the actions by which it manifests itself, 42. 'A perpetual struggle in
organized bodies, between the laws of the vital principle and those of
universal nature, 43. The vital principle resists the laws of chemistry,
of physics and mechanics, 43. There takes place, however, in the ani-
mal economy, chemical, physical and mechanical phenomena, but they
are always modified by the vital principle, 44. Influence of the stature
on the energy of the vital powers and even on longevity, 44. Vis Medi-
catrix naturae, 44. Theory of inflammation, 46. Analogy between the
turgescence of an inflamed part, and of one in a state of erection, as the
penis, %c. 48. Indirectly tonic influence of cold, 49.

§ X. Of the System of the Great Sympathetic Nerve. 9.

These nerves are to be considered as connecting the organs of the
functions of assimilation, as the cerebral nerves unite those of the exter-
nal functions, 49. They are the only nerves found in several animals
without vertebra. They arise from all the vertebral nerves, from which
they receive filaments, as well as from the sixth cerebral pairs, 50. Gan-
glions of the sympathetic nerves; the semi-lunar ganglion, the principal,
50. The great sympathetics render the internal organs independent of
the will, 51.

INDEX. 105

§ XI. Of the relations to Physiology to several other Sciences, 54,

The relation of physiology to physics', chemistry, and mechanics, 54.
Connexion of physiology with human and comparative anatomy, 56. Its
connexion with medicine, 59.

§ XII. Classification of the Vital Functions, 60.

The best divisions of the vital functions is that which was first pointed
out by Aristotle, adopted by Buffon, and completely developed by Gri-
inaud, 60. Modifications of which this division is susceptible ; preser-
vative functions of the individual or of the species, 61. These two great
divisions further divided into two orders, 61. Why man is subject to
more diseases than animals, 63, 64.

Of the arrangement of this work, 66. The voice is a natural connex-
ion between the preservative functions of the individual and those of the
species, 67. The history of the ages and temperaments, and of the
varieties of the human species 5 the account of death and putrefaction
forms a separate appendix, 67.

FIRST CLASS.

Functions subservient to the preservation of the Individual,
ORDER FIRST.

Functions of Assimilation.
CHAPTER I.
On Digestion, 71.

Definition of this function, 71. General considerations on the digestive
apparatus, 72. Connexion between the nature of the aliment and the ex-
tent of the digestive tube, 72. Of aliments, 73. The nutrient principle ob-
tained from the aliment, by our organs, is always the same, 73. Of the
nature of the alimentary principle, 74. Differences of Regimen, ac-
cording to the climate, 75. Hunger and thirst, 76. Mastication, 79.
Action of the lips, of the cheeks, of the tongue, of the teeth, of the jaws,
78, 79, 80. The salivary solution, 81, 82. Deglutition, its mechanism,
83, 84. Deglutition of fluids and of gaseous substances, 85. Of the ab-
domen, 86. Of digestion in the stomach, 87. Different systems of di-
gestion ; of concoction, fermentation, 88. Of putrefaction, 89. Of tri-
turation; of digestion in granivorous fowls, 90. Of maceration, 91.
Phenomena of rumination, 91. Of the gastric juice, 92, Its source, its

O

106 INDEX.

quantity, and solvent qualities, 94. Digestion chiefly consists in the so-
lution of the aliment in this fluid, 95. Singular cases of a fistula of the
stomach, 97. Action of the stomach, 97. Functions of the pylorus, 100.
Of vomiting, 101. Digestion in the duodenum, 102. Of the bile and its
secretory organs, 103. Circulation of the blood in the liver, 104. Uses
of the spleen, 105. Of the pancreas and pancreatic juice, 107. Separa-
tion of the alimentary matter in two substances, the one chylous the other
excrementitions, 108. Of the action in the small intestines, 108. The
uses of their curvatures and valvulae conniventes ; of the peristaltic
motion, 109. Of digestion in the great intestines, 110. Uses of the ap-
pendicula vermiformis of the ccecum. Of the evacuation of the faeces,
111. Intestinal gases, 112.

Of the secretion and excursion of the urine, 113. Of the caliber of
the renal arteries, structure of the kidneys, 114. Action of the kidneys
and ureters, 115. Accumulation of the urine within the bladder, 117.
In what manner itis expelled, 1 18. Physical qualities of the urine, 119.
Chemical analyses of this fluid, urea, 120. Its retention produces urir
nous fever, 121. Experiments on the effects attending retention of urine
by tying the ureters, in living animals, 122. Urinary calculi, why most
frequent in cold and damp climates, 124—125.

CHAPTER II.

Of Msorfition, 125.

Absorption takes place, in every part of the body, both on its surface
and in its internal parts, 125. Absorption more or less active in differ-
ent circumstances, 125. Its activity is very slight on the external sur-
face, except where the skin is thin and epidermis moist, 126.

Absorbing mouths, 130. Their mode of action, in absorption, 130.
Of the lymphatics, 131. Their innumerable anastomoses, from the
union of which there is formed a mesh-work enveloping the whole body,
132. Pathological inferences, 133.

Of the conglobate glands, 134. Their action, 104. Circulation of
the lymph, 134. Observations on cancer, 135.

Of the thoracic duct, 136. Of the physical and chemical properties
of the lymph, 137.

CHAPTER III.
Of the Circulation, 139.

Definition and general idea of this function, 139. Of the action of
the heart ; uses of the pericardium, 140. Connexion between the bulk
of the heart, and strength and courage, 140. Singular case of commu-
nication between the two ventricles, 141. Structure of the heart, 142.
Action of the heart, in circulation, 144. Shortening and pulsation of
the heart, every time the ventricles contract, 145 — 146. The quantity
of blood which these cavities send out, along the arteries, 147.

Action of the arteries, 147; their arrangement and anastomoses, 148,
Of the structure of the arteries, the force and contractility of their dif-
ferent coats, 149. Dilatation of the arteries, 149. Of the pulse and. it*
"ties. 154. Velocity of the circulation aJong the arteries. \*~.

INDEX. 107

Of the capillary vessels, 155. Those which convey a colourless fluid,
136. Of the manner in \vhich the blood flows along these vessels, 157.
Terminations of the arterial systems, 159.

Of the action of the veins, 160. Proportion of the arterial to the^ve-
nous blood 5 difference of arrangement and structure between the ar-
teries and veins, 160. Of the use of the valves of the veins, 161. Gra-
dual increase of velocity in the venous circulation. Of the use of the
vena azygos, 162. Reflux of the blood in the great venous trunks, 163.
Theory of the circulation, 164. Partial circulations in the midst of the
general circulation, 165. Of the two divisions, venous and arterial, of
the circle of circulation, 166. Organs situated on the two points of in-
tersection of this great circle, 166.

CHAPTER IV.

Of Respiration, 167.

Of all the changes, which the blood undergoes, in penetrating through
the organs placed in the course of the circulation, the most remarkable
are those it receives from respiration, 167. Differences of arterial and
venous blood, 167. Of the atmosphere, 167. Action by which respi-
ration is performed, 170. Motions of the ribs, 171. Difficult respiration,
172. Structure of the lungs, 173. Use of the bronchial arteries, 173.
Pulmonary inflammations, 176. Changes on the air and on the blood by
respiration, 177. Vitality of the lungs, 178. Respiration of certain
animals, 179. Division or ligature of the eighth pair of nerves, 182.

Of animal heat, 183. Animal heat is independent of the media in
•which animated beings live, 183. The heat of the animal body ninety-
eight degrees, 184. The lungs not the only parts in which caloric is
disengaged, 184. Caloric evolved, to a certain degree, in all organs re-
ceiving arterial blood, 184. Cutaneous evaporation, the most powerful
means of lowering the temperature, 186. It does not explain, however,
•why the animal temperature remains the same, in a medium hotter than
the body; case of a man said to be incombustible, 186. Effects of cold,
188.

Phenonenon of the circulation of the blood through the lungs, 189.
Pulmonary exhalation, 190. Of asphyxia, from drowning and from
strangulation, 191. From noxious gases and from intoxication, 193.
From obstruction of the glottis; of the asphyxia of new born children,
194.

Of several phenomena of respiration, as sighing, yawning, sneezing,
coughing, hiccup, and laughter, 195. Cutaneous perspiration, 196.
Its connexion with the other functions, 196. Its quantity, 198. Of the
sweat ; of the formation of carbonic acid gas on the surface of the skin,
200. Of the uses of the cutaneous perspiration, 200.

CHAPTER V.

Of the Secretions, 20 1.

Classification of the animal fluids, 201. Chemical classification of the
fluids by Fourcroy, the best, 202. Of the blood. Of its physical, che-
mical, and vital properties, 203. Of sanguification, 204. Of the ef-
fects of regimen on the blood, 205. The transfusion of blood, 208.

108 INDEX.

Of the secretory apparatus, 210. Serous transudation, 210. Secretion
in the mucus follicles, 212. In the conglomerate glands, 212. Of acci-
dental secretions, 212. Influence of the nervous energy on the secretions,
214. Influence of the imagination on the secretions, 217. Quantity of
of fluids secreted, 218.

Secretion of adeps within the cellular tissue, 219. Difference of quan-
tity and quality of this fluid, in the different parts of the body, 220. Of
the uses of the adeps, 220. Circumstances which increase or lessen its
secretion, 221. Analogy of the marrow of the bones to adeps, 22 1. Of
the insensibility of the medullary membrane, 222.

CHAPTER VI.

Of Nutrition^ 223.

Nutrition is the completement of assimilation, 223. Period of the
complete renovation of the body, 223. Mechanism of nutrition ; from
arterial blood only, 224. Difference of vegetable and animal substances,
225. New products, 225. Of the emunctories, 227. General view of
the functions of nutrition, 228.

CHAPTER VII.

Of Sensation, 231.

Functions that are subservient to the preservation of the individual,
by connecting him with surrounding beings. Of sensations, 231. Na-
tural succession to the phenomena of sense, 231—232.

Of light and of colours, 233. Organ of sight — formed of three dis-
tinct parts, 236. Use of the eye-lids, eye-lashes, and lachrymal ducts,

240. Eye-ball, its structure, 241. Mechanism and phenomena of vision,

241. Motions of the iris, 242. Refraction of the rays of light by the
membrane, 243, and by the fluids of the eye ; inversion of objects on the
retina ; point of distinct vision, 244. Defects of vision, 245. Develop-
ment of the eyes and their motions, 246. Errors of vision, 247. Its dif-
ference in different animals, 248.

Organ of hearing; of sound, 249. Structure of the ear, and mechan-
ism of hearing, 249. Difference in animals, 252. Defects of hearing, 252.

Of odours, 252. Organ of smell, 253. Sensation of smell, 254.

Of taste, 255. Of the tastes of different substances, organ of taste,
255 — 256. In different animals, 256. Uses of the nerves of the tongue,
256. Galvanic experiments, on this subject, 257.

Of touch, 258. Its certainty and error, 258. Of the integuments, 258.
Of the nails, 258. Of the hair, 262. Of the hand, 263. Touch in dif-
ferent animals, 265.

Of the nerves, 267. Of their origin in sensible parts, 267. Of their
structure, 268. Opinion of Reil on this subject, 268. Of the manner they
arise from each other, 269. Of their termination in the brain, 269. Of
their comparative size, in different animals, and in man at different
ages, 270.

Of the coverings of the brain, 272. Mechanism of the bones of the
skull and face, 272. Use of the sphenoid, 273. Rounded form of the
skull, 276. Uses of the dura mater, of the arrachnoid, and the pia mater,
276. Size of the brain, 277. Form of the head, 277. Connexion with

INDEX. 109

the intellectual powers, 278. Nerves crossing, 272. Divergent and con-
vergent fibres, 280. Cerebral circulation, 28 1 . Arterial blood retarded,

281. Jugular veins, 282. Connexion of the action of the brain and heart,

282. Theory of syncope, 284. Motions of the brain, 286. Experiments,
290. Action of the nerves and brain, 293. Principle of motion and sen-
sation, 294. Different intellectual functions of different parts of the brain,
295. Not yet perfectly understood, 295.

Analysis of the understanding, 295. Perception, 296. Reasoning and
instinct, 297. Generation of the faculties, 298. Sensation, perception,
attention, memory, imagination, association of ideas, comparisons, judg-
ment, reasoning, 299. Influence of signs on the faculties of thought, 300.
Analysis of ideas, by M. Destutt Tracy, 302. Derangement of the mind,
302. Mania, 303. Idiotcy, 303.

Of the passions, 303-T-304. State of the intellectual powers connected
with them, 305. Effects on the animal enconomy, 306. Of sleep and
waking, 307. Repose of the functions which connect us with surround-
objects ; condition of the functions of assimilation, during sleep, 308.
Proximate cause of sleep, 310 — 311. Of dreams and somnambulism,
313. Animals are also subject to dreams, 313.

CHAPTER VIII.

On Motions^ 3 1 4.

This chapter treats only of voluntary motions, whose organs may be
distinguished into active and passive (the bones and muscles,) 3 1 4. Struc-
ture and properties of muscular fibres, 315. Of the tendons and aponeu-
roses, 316. Phenomena of muscular contraction determined by an act
of the will, 317. A sound state of the nerves, arteries, and veins belong-
ing to a muscle is necessary to its action, 317. Theory of this action,
318. Preponderance of the flexor muscles over the extensors, 318.
The preponderance varies, according to the age, in the state of health
or disease, 319. Of the power of the muscles ; it bears a proportion to
the number of their fibres, 32 1 . The degree of shortening of which they
are capable is proportioned to the length of their fibres, 323. Direction
of the motions performed by the action of the muscles, 323. Of muscu-
lar flesh, 324. Galvanism, 326. Volta's apparatus, or Galvanic pile, 326.
Effects of Galvanism, in the treatment of disease, 330. General view of
the osseous system, 332. Of the vertebral column ; it forms the most es-
sential part of the skeleton, 334. Difference of the stature at different
times of the day, 335. Of the lower limbs, 335. Structure of the bones,
336. Uses of the periosteum, and of the marrow, 338. Theory of ne-
crosis, 339. Of the articulations, 340. Of the articulating cartilages,
341. Of the synovia, 341. Theory of anchylosis, 343.

Of animal mechanics ; of standing, 344. Of the centre of gravity, 344.
Tendency of the body to fall, 344 — 347. Standing is performed by an
effort of the extensor muscles, 348. Reasons why it is impossible for a
new-born child to stand, 350. Man is the only animal that can stand up-
right, 350. Of falls, 351. Of standing on one foot, 352. A degree of
separation of the feet necessary in standing, 352. Of kneeling 5 of sit-
ting; of the recumbent posture, 354. Of lying on the sides, 354. Of
the prone and supine postures, 355. The different modes of recumbent
posture have a reference to the degrees of facility of respiration and to

IK) INDEX.

the period of life, 336, Recumbent posture on an inclined plane, neces-
sary, especially to old people, 357. Of motions of progression 5 of
walking, 358. Of walking up or down an inclined surface, 360. Me-
chanism of the articulation between the leg and foot, 361. Of running,
362. Of leaping, 363. Leaping- is performed by the sudden extension
of the lower extremities, previously in a state of flexion, 634 — 365. Of
the vertical and oblique leap, 365. Of swimming; man swims with dif-
ficulty, 365. Swimming natural and easy to fishes ; its mechanism, 367.
Of flying, 368. The structure of the body in birds favourable to this ac-
tion; how performed, 369. Of crawling, 371. All the phenomena of
animal mechanics may be referred to theory of the lever of the third
kind, 370. Partial motions performed, by the upper extremities, 360. Of
climbing; of pushing, 360. Of throwing a projectile, 360. Partial mo-
tions, as signs expressive of ideas; of gestures and attitudes, 369.

CHAPTER IX.

Of Voice and Speech, 370.

Definition of the voice and of speech ; circumstances necessary to the
formation of the voice ; its organs, 371. Opinions of Ferrein and Dod-
art, on the uses of the glottis, 371. The larnyx is, at once, a wind and
a stringed instrument, 372. Of the power of the voice 5 of speech ; man
alone is capable of speech, 373. Of the vowels and consonants, 374. Of
song and music, 375. Of stammering, burr, and dumbness, 375. In-
struction of the deaf and dumb, 376. Ventriloquism, 52 1.

SECOND CLASS.
CHAPTER X.

Functions subservient to the preservation of the Species.
Of Generation) 381.

Difference of the sexses, 381. Case in which the sexual organs did not
exist, 381. Hermaphrodism is never met with in the human species, 383.
Man, in the exercise of the functions of generation, not under the control
of the seasons, 384. Of the organs of generation, in man, 384. Of the
female organs of generation, 386. Of the signs of virginity, 387.

Of erection, 386. Of the human semen, 388. Of the ovaria, 390. Of
the impregnation of the ovum, 393. Of barrenness, 394. Systems of ge-
neration, 394. Gestation, 397. Of the foetus and its coverings, 400.
Of the development of its organs, 400 — 40 1 . Of circulation of the blood,
in the foetus, 40 1 . Of the placenta, 40 1 — 402. The umbilical cord, 404.
Mode of existence of the foetus, 405. Morbid affections to which it is
subject while in the womb, 406. Of monsters, 407. Their different kinds,
and the causes which produce them, 408. History of a remarkable case,
409. Of the chorion, of the amnion and liquor amnii, 409. Of the allan-
tois and urachus, 410. Of the natural term of gestation, 412. Of par-
turition, 412. Of the mechanism of parturition, 413. Of twins, 413. The
number of male children born exceeds that of temale, 414. Of superfce-

INDEX.

tations, 416. Of suckling, 418. Sympathy between the uterus and mam-
mae ; structure of the latter, 419. The milk appears to be brought to the
breasts by the lymphatics, 420. Chemical qualities of the milk, 420.
Connexion between the new born child and the mother, 421. Imperfect
development of ihe foetal lungs, 422.

CHAPTER XL

Containing the History of the ages, the Temperaments, and the Varieties of
the Human Species ; of Death and Putrefaction, 421.

Of infancy ; of detention, 422. Ossification, 423. Phenomena of puber-
ty, 424. Connexion between the development of the sexual organs and the
voice, 425. Of menstruation, 426. Of the cause of menstruation, 426. Of
the cessation of this evacuation, 427. Of manhood, 428. Of tempera-
ments and idiosynbrasies, 429. Of the sanguine temperament, 430. Of
the muscular or athletic temperament, 433. Of the bilious temperament,
produced by an increased energy of the hepatic system, joined to con-
derable activity of the sanguineness system, 434. Of the melancholic
temperament, 434. Lymphatic temperament, 435. Nervous, 435. Mixed
and acquired temperaments, 435. Influence of climate on tempera-
ments, 435.

Varieties of the human species, 436. European Arab race, 436. Ne-
gro, 437. Mogul, 437. Hyperborean, 437. Moral characteristics of the
different races, 438. Giants and Dwarfs, 439.

Of old age and decripitude, 439. Decay, 439. Death, 441. Gradual ex-
tinction of bodily and mental powers, in the reversed order of their pro-
duction, 442. Period of death, 443. Probabilities of human life, 444 —
446. Of putrefaction, 446 — 448.

Notwithstanding all the care we have bestowed on this
volume, some unavoidable literal errors will be found in dif-
ferent parts of the work ; these being obvious, the reader is
requested to correct for himself.

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