Contagious * Epidemic  Diseases
CONSIDERED WITH REFERENCE TO
Quarantine and  Sanitary Laws.
-  IS YELLOW FEVER CONTAGIOUS ?
B Y-
      C. W.  CHANCELLOR, M. D.

I.ate Professor of Surgery in the Washington University, Baltimore
   Secretary of the State Board of Health of Md.; Member of
      the American Public Health Association; Editor of
         the "Sanitary Messenger," &~"C, &*c, &*c.
4^
      BALTIMORE:
i=ssxi^Ta:E=! bt roHw cose.
  Corner Pratt Street k Spear's Wharf.

         187*. 
 
f/Vith  Uif  respects of

idanceMvi.
fin {/imore-, </h7. 
 
Contagious • Epidemic  Diseases
CONSIDERED WITH REFERENCE TO
Quarantine  and  Sanitary  Laws.
IS YELLOW FEVER CONTAGIOUS ?
B Y-
      C. W. CHANCELLOR,  M. D.

Late Professor of Surgery in the Washington University, Baltimore;
   Secretary of the State Board of Health of Md.; Member of
      the American Public Health Association; Editor of
         the "Sanitary Messenger," &°c, &*>c, <W.


      BALTIMORE:
FEHTTED E^Z- JOHN COX,
  Corner Pratt Street b Spear's Wharf.

         1878. 
PROPOSITIONS.
i. what is a contagious disease?
2. what is an epidemic disease?
3. is y'ellow fever contagious ? 
                    THE

CONTAGIOUSNESS  OF YELLOW FEVER.
  In collecting, enforcing and adding to the evidence accu-
mulated upon this most important subject, no claim is  laid
to originality ; the  facts  presented  are simply  a reproduc-
tion of the  experience and opinions of wise investigators,
given for the most part in their own language.  Its value
does not consist in vague speculations, based upon limited
experience,  but in the mass of evidence gathered from  the
researches and writings of experienced and reliable scientists.
  A contagious disease is a disease which  is communicated
from person to person.  An epidemic  disease  is a disease
which at  certain periods  prevails over the whole, or over
a large portion of a  community.   A  sporadic  disease is
a disease  which  arises either  in a single instance, or of
which the cases  at  one  time are few and scattered.   The
cause of a contagious disease  is a specific animal poison.
The cause of an epidemic disease is, or rather is supposed to
be, a certain condition of the air.  A contagious disease pre-
vails by the communication from person to person of  that
specific animal  poison from which  the  malady derives its
existence.  An epidemic disease prevails through the  in-
fluence of the atmosphere.  The specific animal poison which
gives origin to a  contagious  disease must  have existed in
some person, and have been communicated from that person
to another, by actual contact, before such a disease can be
propagated.  The application by contact of its  own specific
virus is indispensable, as a first step, to  the progress  of a 
4
contagious disease ; it is essential to every subsequent step.
For the extension of an epidemic disease, on the contrary, it
is only necessary that a person  (provided he be predisposed
to receive  the malady,) be surrounded  by the noxious air
from which the epidemic arises.  A distinction has, indeed,
been made between  contagious  disease which  is communi-
cable by palpable matter, and one  which is communicable
by invisible effluvia.  Whether  its  application to any part
of the body of the  individual  who receives it,  can be dis-
tinctly traced or not, it  must come in contact with some part
of his body.   The small-pox is  communicable by the appli-
cation to a healthy person of the matter contained in its pus-
tules, it is also communicable by placing a healthy person
within a certain distance of the diseased ; in the former case
the application of the morbid matter is palpable ;  in the lat-
ter  case it is not palpable, it is  too subtle to be appreciated
by the senses, it is conveyed through the medium of the air;
but its  application is  as real,  and  as really by  contact, as
when it is applied by the lancet of the  innoculator.
  In the whole range of politics, nay,  even in that of theo-
logy itself, there  is no subject on which such vague  notions
have prevailed ; none respecting which men's  minds  have
been so completely and so generally mystified as that of con-
tagion.   The  subject of contagion   certainly opposes  to its
investigation no particular difficulties ;  but by the aid of one
enormous assumption, and by neglecting to distinguish be-
tween one or two circumstances, which it is essential to dis-
criminate, the extent to which both  medical  and unprofes-
sional men of the greatest  intelligence have allowed  their
understanding to be  abused, is  perfectly astonishing.   For
several centuries the subject of contagion has had the singu-
lar  property of depriving the physician, the philosopher and
the statesman of the power  of applying to its investigation
the commonest rules of reasoning ;  and men have argued on
this topic, apparently to their own satisfaction,  and  to that
of others, in a manner which would have covered  them with
shame, and overwhelmed them with  contempt,  had they so
done with reference to any other subject of  human inquiry. 
5
And yet it is a subject on which it is of great importance that
the ideas should be clear and the judgment sound.   It is in-
timately connected with the life  or death of millions of the
human race ; it is interwoven with the  commercial welfare
of nations,  and with the interests of this country in particu-
lar ; and the whole system of quarantine laws should be  en-
tirely dependent upon it.  To this subject the anxious attention
of national legislatures has been directed more than once.   In
1824 a committee of the House  of Commons thus  recorded
their opinion on the matter :  " The influence  which this
law (that of quarantine) is supposed to have in the protection
of public health, its  bearing on some of our strongest preju-
dices, and its containing the various precautions which have
been long deemed our safeguards against the introduction of
contagious  diseases, from whatever part of the world the
danger may be apprehended, renders every recommendation
that may affect it a matter at once of  general  interest  and
peculiar delicacy.  On the one hand care is to be taken that
in  the  attempt to  relieve commerce from burthens and in-
conveniences which press upon it, and to afford it the greatest
freedom of which it is susceptible, we do not expose the
country to  the most formidable risk.  On the other hand,
that neither ancient  jjrejudices,  nor an excess  of anxiety to
avert possible danger, should induce the  continuance of  re-
strictions inessential to their object; and should thus deny
to the trade any of those  facilities which, consistently  with
every prudential regard to considerations of protection and
safety, it may be permitted to enjoy/'
   The subject is now about to undergo an investigation by a
Committee  of the Senate and House  of Representatives of
the United States, and it is  of the utmost importance that
those who are to engage  in  the  inquiry  should  come to it
with some real  and correct information, and  with unpreju-
diced minds.  The data submitted to the  American Public
Health Association, at its late meeting in Richmond, Va.,
was not sufficient to justify that body in committing itself to
any special theory in connection  with the origin and preven-
tion of yellow fever,  notwithstanding the manifest prejudice 
6
with which many came to the meeting in favor of declaring
yellow fever a contagious disease.  In this instance igno-
rance was not blamable, and prejudice was unavoidable, for
the investigation was hastily instituted, and the report of the
commission was neither complete nor exhaustive.

                 CONTAGIOUS DISEASES.

  Before proceeding to consider the question of contagion, it
may be proper to observe that it is by no means exclusively
a medical question ;  it is really a question  of science, to be
decided by facts which  every one can understand ;  a question
of testimony, to be determined by evidence  which every one
can appreciate.   There are circumstances which  render medi-
cal  men  peculiarly  unfit to  investigate the subject.  Few
members of a profession are capable of taking anything but
a professional view of any professional subject.  In medicine
the authority of the master has at  least as much  influence
over the mind of the student as it has in any. other science.
On this subject, in particular, pupils, before they are capable
of forming  an  opinion for  themselves, are taught  in  the
schools certain dogmas, which  are inculcated  upon them
with extraordinary earnestness ;  their minds  are trained to
take only one view of a subject, and to consider  all doubt on
the matter as leading to the most terrible consequences.  It
is, therefore, only now and then  that a man arises, endowed
with extraordinary power, or placed in circumstances pecu-
liarly favorable to the discovery of the truth, who is found
capable of making that mental effort,  which it  is necessary
to exert in order to unlearn ;  to disregard the undue author-
ity  of the master ;  to look into nature as an original and in-
dependent observer ; to see what is passing around him with
his  own  eyes, and to judge  with  his own understanding.
Among the members of the  Spanish  Cortes, in 1822, there
were  nine  medical  men.  The subject  of contagion  was
brought  before the  consideration  of  that  body.  It was a
subject in which the  Spanish Cortes could not but feel a deep
interest, in consequence of the fever which  had so recently 
7
depopulated numerous  cities of  the  Peninsula.   So  over-
whelming did the evidence adduced to prove that the  fever
which had lately raged in Spain was not contagious, appear
to the Assembly, that, in opposition to the unanimous opin-
ion of the nine medical men of their  own body, as well as
that of an immense majority of the physicians of Spain, they
rejected altogether, after a solemn debate, and by a majority
of sixty-five to forty-eight votes, the project of a code of san-
itary laws, which had been for years in careful preparation,
successively by a commission of the government,  and two
committees of the Public Health of the Cortes.  Here evi-
dence in support of an undoubted truth, relating  to a  ques-
tion which might have been deemed exclusively professional,
sufficient to satisfy a majority of sixty-five to forty-eight un-
professional members,  was not sufficient to satisfy a single
individual out of nine professional men !
   It  has  been stated  that a contagious disease is  a disease
capable of being communicated from person to person.  It is
produced by an animal poison, and it has no  other known
cause.  This animal poison is the product of a peculiar secre-
tion of the animal economy.   The character which is essen-
tial to it is the power of producing, when applied to a healthy
person, a similar disease.
   All the diseases to which the human body is subject  are
divided into acute and chronic.   Contagious diseases, in like
manner, are either of an acute or chronic character.  Exam-
ples  of  acute contagious  diseases are  the  small-pox and
measles;  of the chronic the  venereal, the itch, and  a few
others.
   That species  of contagion by  which certain chronic dis-
eases are propagated  is so obvious as to require no discussion.
The morbid secretion upon which it depends is palpable, the
application of it is direct, the effects  are visible, and can be
observed and  marked through every  stage, from  their com-
mencement to their termination.   With the single exception
already adverted to, the same is true of that  species of con-
tagion upon which acute  diseases depend.   The small-pox
secretes  a contagious matter which  is contained in its pus- 
8
 tules ; the measles secretes a contagious matter which is con-
 tained in  its vesicles.  Apply a  portion of the fluid con-
 tained in  the pustules of the  one, and the vesicles of the
 other, to  a healthy person; it will excite  the same train
 of symptoms as existed in the individual in whom the con-
 tagious matter was secreted.   Moreover, persons who  ap-
 proach within a short distance of the affected, and who do not
 come into actual contact with them, are often attacked  by
 these maladies ; but this is never the case with chronic con-
 tagious diseases, in all of  which the contact must be direct.
 It has been already shown, however, that even in  the former
 the contact is no less real, though  it is not visible, and that
 the contagious matter, in a form too subtle to be appreciated
 by the senses, is conveyed from one body to another.  The
 origin of contagious matter,  like the origin of every natural
 production, is concealed from  the scrutiny  of man.  We
 know nothing of it;  but of the nature of the diseases it pro-
 duces, this much, at least, is certain, that they depend upon
 a peculiar animal poison, and that  they are  propagated by
 the communication of that poison from person to person.
  It would have been reasonable  to suppose a priori that
 diseases arising from causes thus  specific,  would  observe
 peculiar laws.  They are  found to do so, and a knowledge
 of these laws is essential to the understanding of this subject.
  '1. Contagious diseases  produce certain phenomena ;  that
 is, a combination of certain symptoms.   These symptoms are
 determinate and uniform ; they are always  the same ; they
 never vary, except  in degree.   In  every individual, under
 every variety of age, sex, condition and mode of living, in
 every country, in every season of the year, and in all possi-
 ble states of the atmosphere, these symptoms are precisely
 the same.   The operation  of any one, or of any combination
 of these agents, so powerful in modifying disease in general,
 is only to render the symptoms of a contagious disease more
or less mild or malignant.  The symptoms  themselves are
uniformly  the same.  The small.pox  is never  without its
pustules;  the measles is  never without its vesicles; the
virus of small-pox never produces the symptoms of measles ; 
9
that of measles never produces the symptoms of small-pox.
Each disease preserves, under every variety of circumstance,
the same specific character.
  2. The phenomena  produced  by contagious diseases are
not only determinate in themselves, but they are uniform in
their accession, in  their progress, and in their  termination.
Beyond certain  limits, which are  narrow and fixed, they
never vary in either of these respects.   The small-pox pro-
duces its  appropriate  symptoms  in a certain time after the
contagious matter  has  been  received.   First, certain  symp-
toms arise ; these are succeeded by others ; this  succession
takes place in a  certain order ; the symptoms  come to their
height in a certain period ; they  decline in  a certain man-
ner ;  they tei ruinate in a certain time  The period also
when the disease has run  its  course, and ceases to be con-
tagious, that is,  ceases to exist, is determinate.  All these
things are regular as the  course of the planets.  In  small-
pox the law of the disease is that no contagion takes place
until the eruption  appears ;  and that  it  remains as long as
there is  any scab  on  the skin.  The period which elapses
between the reception of the contagious matter  and  the first
appearance of the  disease in small-pox from innoculation is
8 or  9 days.  Thus, of 810 inoculated  cases,  in 519 fever
commenced before  the ninth, in 219 on the ninth day.  The
exceptions are extremely rare in which it either anticipates
or exceeds this period.   In the casual, or what  is  called the
natural small-pox,  the latent period is somewhat longer than
in the innoculated ; but the utmost range is only from ten to
sixteen days.  The latent period of the contagion of measles
is from ten to fourteen days.   The other phenomena of these
diseases succeed  each other with a like regularity.
  3. The morbid  matter producing   a  contagious  disease
being once secreted, that disease can be propagated  at any
time, and among any number of persons.  So long  as it re-
tains its energy this specific  virus never ceases to produce  its
specific effects ; these effects  can  be produced  by no other
cause.  From this law it follows that no disease which is not
contagious at its commencement can become contagious in 
10
its progress.   The spontaneous generation of a contagious
disease is as great an absurdity as  the spontaneous genera-
tion of an animal.  Nor, on  the other hand, can  a disease
which is contagious in its commencement cease to be conta-
gious in its progress.  The notion that  a fever may  arise
from cold,  from wet, from  a peculiar constitution of the
atmosphere, or from any of the common causes of fever, and
become contagious in its progress, originated in an ignorance
of the laws of the animal economy, and has been perpetuated
in consequence of inattention to those laws.  No man of
sense can consider  what a contagious  disease really is, and
what the ascertained laws of the animal economy are, with-
out perceiving that this  notion of the generation of a con-
tagion  must be  false.   To  suppose, indeed, that a disease
non-contagious in its commencement may become contagious
in its progress, or  the converse, is to imagine in the animal
economy precisely the same absurdity  as  it would be in the
vegetable were an acorn, by a change  of  soil  or  climate, to
cease to produce an oak and generate a bramble.
  4.  Acute contagious diseases, as  a general rule, are capa-
ble of affecting the same person  once only ;  chronic conta-
gious diseases are capable of affecting the same person more
than once.  On what this peculiarity depends  we do not
know; it  is an  ultimate fact, but  the fact itself is certain.
Cases, indeed, are  on record of the occurrance of acute con-
tagions, as srnall-pox and  measles, more than once in the
same individual; allowing  the perfect accuracy of the ob-
servations on which these statements are  made, it must still
be conceded that it is an event so  seldom  witnessed that it
can be ranked only with the most singular of the exceptions
which are known to exist to any general rule.
  5. Strictly connected with this law, and as a consequence
of it, there follows one negative character of an acute conta-
gious disease, namely—when it has once  gone through its
course there can be no relapse.  It is impossible,  either in
that weakened state of the body which immediately  succeeds
an acute disease, or in any  other condition of the  constitu-
tion, whether by exposure to the common causes of  fever, or 
11
 by an application of the specific virus in any degree of inten-
 sity, to re-excite the original train of symptoms.
  ^ It might reasonably have been thought impossible that
 diseases so uniform, so specific, could be confounded with
 any other maladies.  Yet there is an important class of dis-
 eases with which they have been  generally confounded, and
 with which they not only have nothing in common, but to
 which they afford a perfect contrast, namely—

                   EPIDEMIC DISEASES.

   The term epidemic, considered etymologically, merely sig-
 nifies generally prevailing; but in  medicine it is universally
 appropriated to designate a certain class  of fevers.   These
 fevers are highly malignant; they occur frequently ; they
 spread extensively ; they prove  more mortal than  all other
 diseases together.  Supposing mankind  to  consist  of one
 thousand millions ; it is computed that thirty millions die
 annually from all diseases, and that of this number fifteen
 millions, that is one-half, die of epidemic  maladies.   These
 diseases, therefore, possess an extraordinary interest and im-
 portance.  Epidemic diseases appear  to derive their origin
 from one cause, namely—the state of the air.  A  certain
 condition of the air is supposed to produce epidemic diseases,
 because the hypothesis  affords the best solution of all  the
 phenomena which they exhibit.   What that constitution of
 the atmosphere is which gives rise, in any case, to  an epi-
 demic disease,  we do not know ; therefore we cannot know
 what the peculiar constitution of  the  atmosphere is which
 gives rise to peculiar epidemics.   This is  the all-important
 question.  It is reasonable to believe  that there are certain
 qualities of the atmosphere which have a considerable in-
 fluence in the generation of these diseases, namely—its heat,
 cold, moisture, dryness, and electrical state ; but  what  de-
 grees and combinations of these  qualities are connected with
 the production  of epidemic diseases, we do not know.  We
 have derived from experience the certain knowledge of one
fact only, namely—that these  maladies are generated most 
12
frequently, and in the most malignant form, by a moist and
warm atmosphere.  It has, morever, been supposed that cer-
tain changes may take place in the constitution of the air
which  are  not perceptible by our  senses, and that these
changes may have the most important  influence on  human
health and life.  These occult properties remain to be inves-
tigated.
  In assigning certain conditions of the air as the cause of
epidemic diseases, we are able to advance one step.   The air,
it is certain, is often charged with  noxious exhalations aris-
ing from the putrefaction of animal and vegetable matter.
These exhalations are generated in  certain  localities, notably
where stagnant water contains dead vegetable  matter ; and
their production is generally promoted by  heat.  Their pre-
cise nature is not known, for they have never been obtained
in a separate state ;  but it is certain they are  suspended in
the air; that,  naturally, they do not extend far beyond the
place where they are generated; that by  currents of wind
they are capable of being conveyed to a great distance ; that
they exert a powerful agency in producing some of the most
malignant fevers ; and that a long continued exposure  to
them tends to  shorten the duration of human life.
  Epidemic diseases observe certain laws, and these laws, it
will be seen, are the complete contrast of those which regu-
late contagious diseases.
  1. The phenomena of epidemic diseases  are  not determi-
nate and uniform; they are diversified  in the highest de-
gree ;  not only in different countries and different seasons,
but in the same country and  in  the same season.  These
symptoms observe no regular concourse;  they do not suc-
ceed each other in any determinate  order ;  there is no dis-
cernible connection between the  application of their cause
and the appearance  of its effects ; their duration is variable.
The phenomena  of contagious diseases, on the contrary, as
has been shown,4§> determinate ;  the order  of their succession
is regular; the period which elapses between  the applica-
tion of their cause and the appearance of its effects is fixed;
their duration is uniform. 
13
  2. Though there is the greatest possible diversity in the
phenomena  of  epidemic diseases, yet in all countries the
periods at which they commence, decline and cease are some-
what determinate and exact.   These periods correspond with
certain states of the season.   They differ  in  different coun-
tries according to their geographical posi'ion, and they may
be anticipated or postponed by circumstances, but in general
they are  remarkably  uniform.   In Asia Minor, Egypt and
Syria they commence in March or April, and cease  in  June
or July ; in most  parts of Europe and  in  North  America
they begin in July or August, and end in November or De-
cember.   All ihe epidemics of yellow fever  in  the United
States, of which we have any certain record, have appeared
in June,  July or August, and committed their greatest rav-
ages in the months of August, September and October.
  3. Epidemic diseases commence,  spread  and cease in a
manner  perfectly  peculiar.   They arise,  for  example,  in
some particular quarter of a town, or in some district. They
do not proceed to attack other places in succession, accord-
ing to their proximity to the quarter first affected,  but they
break out at once in  the most distant and the  most opposite
directions.  They  prevail, suppose,  in  a  certain  district;
suddenly they diminish or cease there, and appear in another
quarter,  it may be, the most remote from  the first ; then
they may again return  to the place first attacked, or they
may suddenly appear in a spot near to it, or in  one  in  an
opposite  direction.  People are attacked, not  in proportion
as the inhabitants of the affected mix with those of the un-
affected places, but in proportion as the inhabitants of the
unaffected expose themselves to the air of the affec ed places.
The visit! of the  sick to unaffected  places is followed by no
increase  of the  disease, unless a favorable  condition of the
atmosphere  exists in the place ; the visits of the inhabitants
of an unaffected to an affected place  Wattended with  a cer-,
tain increase  of sickness.  The  liability of persons to the
epidemic of yellow fever on their  arrival in the infected dis-
trict is proverbial.  On their removal from a noxious to a
pure air  the sick often rapidly recover; but they do not com- 
14
municate the disease to the inhabitants of a pure atmosphere.
The manner in which  epidemic diseases  terminate  is most
peculiar and characteristic.   It  is precisely  at the period
when the greatest number of persons are affected, and when
the greatest mortality  prevails that  these  maladies  rapidly
decline and suddenly cease.   Ther^  is scarcely an exception
to this law in the history of epidemic diseases.  It perfectly
accords  with the nature of the  cause  upon which epidemics
are here supposed to depend ; it is totally inexplicable upon
the hypothesis that they are produced  by contagion.  To
suppose that a disease which is propagated by contagion  can
rapidly  decline, and even suddenly cease,  at the very period
when the greatest number of persons are affected, and when
the greatest mortality prevails, that is, when the contagious
matter is proved to be in its most  active and malignant state,
is utterly absurd.  So true is this, that the most intelligent
and candid  contagionists acknowledge, in so many  terms,
that this important fact is perfectly inexplicable upon their
system.   "It is a very common fact," says one  of the most
distinguished and able advocates  of the common doctrine of
contagion,  " and perhaps wholly  unaccountable upon  any
theory of the propagation of contagion,  that pestilential dis-
eases, after  running an indefinite course, notwithstanding
all  the  measures  adopted to  restrain their  progress, fre-
quently cease spontaneously, at a  time when the walls of the
houses,  furniture, &c , must still  be  supposed to be highly
impregnated with the contagion."  The fact  is indeed cer-
tain ; it is most distinctive of these two classes of diseases ;
it is alone sufficient to  prove  that they are essentially dif-
ferent.
  Were the common  term  epidemic  confined  to its strict
etymological signification—generally prevailing—it, would be
correct to say of the small pox,  ibr example, when  gener-
erally prevailing,  that  it was  epidemic.  But  this term
should be appropriated only to the designation of a class of
diseases observant of the laws which have  been stated.  To
call any disease epidemic, therefore, merely because it is gen-
erally prevailing, unless it be also obedient to all the other 
15
laws which characterize epidemic diseases, must lead (and
the history of this subject affords abundant proof that it has
led) to the most pernicious confusion of ideas.
  It has been shown that fever is capable of being produced
by  two causes :  by a specific contagion, and by a peculiar
constitution of the air, which for the sake of distinguishing
it from its other states, and of expressing the fact that it is
the cause  of epidemic diseases, may be  termed its epidemic
constitution ;  it is commonly called a pestilential constitu-
tion ; but fever is capable of being produced by another, and
a totally different condition  of the air,  namely, by the cor-
ruption of it.  This corruption may take place in  various
ways, and exist in various degrees of intensity, and its effects
will vary  accordingly from  the headache produced by a
crowded theatre to  the  mortal fever occasioned by such a
corruption of it as occurred in the black hole  of Calcutta.
There is evident difference between an epidemic  constitution
of the  air, and a corruption of it.   We know nothing what-
ever of the change of properties of the  air which renders it
capable of producing pestilential fever ;  investigation should
be  specially directed to  this  point.   The  effects of an epi-
demic  constitution of the air extend  over a whole country,
or  over a  1 irge portion of it, while  the effects of a simple
corruption of the air are confined to that particular spot in
which  the deterioration takes place.
  Corruption of the air  may be produced by three  causes:
1st  By the  confinement of the healthy exhalations of the
body, as in crowded and ill-ventilated apartments.   2d.  By
the confinement of the  morbid exhalations  of  the  human
body, as in hospitals where people laboring  under diseases
are crowded together, and the air is filled with the poisonous
effluvia of sores, mortifications, dysenteric and  other fceted
excrements.  3d. By exhalations arising from the putrefac-
tion of animal and vegetable matter.
  Forestus  mentions a  malignant fever  which  raged at
Egmont in North Holland, occasioned by the putrefaction of
a whale which had been  left on the shore.  Senac gives an
account of a malignant fever which was excited by the ac- 
16
 cumulation of the offal of a city without the walls.   It was
 received into a ditch filled with water ; while covered by the
 water no bad consequences resulted ; but when the quantity
 increased so that it rose above the  surface, a dreadful fever
 spread through the city and its neighborhood, so that where
 four hundred used to die yearly, the deaths were  increased to
 two thousand.   The malignant fevers which prevail  in low
 marshy  situations, particularly in warm weather,  are ex-
 amples of the effect of the putiefaction  of vegetable matter
 in  producing  these  diseases.   Decaying  vegetable  matter
 produces congestive malaria, and decaying animal  matter
 produces the type of miasma which causes typhoid or typhus
 fever ; the  atmosphere vitiated by a conjunction of these two
 poisons may serve as a medium for the spread of yellow
 fever where the germ of the disease exists, either by impor-
 tation or by  hibernation.  Nothing  is  surer  than  that
 typhoid fever is produced  by animal affluvia, and if at the
 same time a vegetable malaria, such as will produce a high
 grade of remittent bilious fever,  is prevalent, a  typho-
 malarial disease, akin to yellow fever, will be produced.
  The fevers produced  by  an  atmosphere thus  corrupted,
 have generally  been  stated to be  produced by contagion.
 Most authors who have observed and recorded facts  similar
 to those which have been mentioned, have represented them,
 not as proving the power of a corrupted  atmosphere to ex-
 cite malignant fever, but as  establishing its power to gener-
 ate contagious fever.  But it  is obvious  that they  do not
 afford the slightest evidence of the existence of a contagious
 influence; that the supposition of contagion is entirely gratu-
 itous ; that the exact and only point they prove is the power
 of a corrupted air  to produce malignant  fever ;  that other
 evidence  is  necessary to prove that  the lever so produced is
 contagious, namely, evidence that  when once generated it
 reproduces itself by contact of the  sick with the healthy in
a pure atmosphere, and that it observes all the other  laws of
a contagious disease.  The single error of thus confounding
 the influence of a corrupted atmosphere with the generation
and communication of a specific animal poison, has produced 
17
the most extraordinary and universal  confusion of ideas on
the subject, and the removal of this source of misconception
is  all that  is  now needful to render  it perfectly luminous.
We hope and believe, it will be felt to  be so by every intelli-
gent and unprejudiced mind.
  There is one fever, for the especial purpose of elucidating
the nature of which, we have entered into  this discussion,
namely,

                  THE YELLOW FEVER.

  The point to be ascertained is, whether or not this fever is
contagious ; and in order to arrive at  the truth, it is only
necessary to examine whether it conforms to the laws of con-
tagious or epidemic diseases.   Let us then attend to the his-
tory of this fever with a special reference to this matter.  We
will take the fever of Barcelona, Spain, in 1821, as a prototype
of the fever which prevailed in the lower Mississippi Valley
last autumn.  Of the fever of Barcelona in 1821, Dr. Maclean
has given so complete and masterly an  account, that in order
to clearly exhibit its nature, (and it may stand as a paradigm
of yellow fever,) it is only necessary to select from the facts
with which  he has supplied us.
  1. In the first place it appears that this disease was singu-
larly diversified in the forms it assumed ; that the combina-
tion,  the  succession and the degree of its symptoms were
so different in different cases that it was difficult to assign to
it any fixed and invariable progress, and that it was exceed-
ingly irregular in  the slowness or the quickness of its course.
In all these  respects it conformed to the first law of epidemic
diseases, and was  in contrast  with that of a contagious dis-
ease.
  2. This fever commenced in August, that is, precisely at
the period of the year in which epidemics have always been
known to manifest themselves in Spain in similar latitudes.
Thus in the epidemic which prevailed in Andalusia, in 1804,
out of the twenty-three towns which it attacked that  year,
it  commenced  in  the  month  of August in ten, and in Sep-
tember in eight.   The fever  of Barcelona continued  to in- 
18
crease  till  the  middle of October;  the  greatest mortality
took place on the 19th of that month.  This is also in strict
conformity to the regular course  of epidemics.   In the epi-
demic of 1804,  in  sixteen tows in Spain, the greatest mor-
tality  took place  in the month of October ; in  Cadiz, in
Alicante,  and  at  Gibraltar, by a singular coincidence,  it
took place  on the same day, namely, the  9th of that month.
From the  19th of October the fever of Barcelona gradually
declined, and subsequently it continued to diminish, in a
regular and progressive  manner, until its total disappear-
ance.  Thus the fever conformed  to  the  second  law of epi-
demic diseases.
  3. It appears, that in Barcelona, from  the  neglect of the
public police for many years, the sewers,  drains, canals  and
other channels for  carrying away  the impurities of the city,
had been choked up, and become foul to such a degree, that
towards the end of June it  was impossible to  pass by the
sea-wall, where they were discharged into the harbor, with-
out  being  incommoded  by the  stench of accumulated  and
putrifying  animal and vegetable substances.   A committee
which was charged with the office of cleansing the port, dis-
covered that the water course was obstructed at its mouth
by a bank  of sand, which prevented its discharge,  and, con-
sequently,  that a large quantity of stinking water was col-
lected,  the product of  various  manufactories, slaughter-
houses, wash-houses and other establishments situated on its
banks,  exhaling an insufferable stench.  The  foul  water
which stagnated around this sand bank was one  foot higher
than the level of the sea.  Now in the houses of Barcelona
which faced the port, in  the streets  de los Encantes, de la
Merced, Mencado and others adjoining the focus of infection,
the  mortality was horrible and  nearly  general ;  whilst  in
the  streets of Santa Anna,  Tallers, San Padro, which are
higher, and in  others which are exposed to the north, and
which  are most distant  from  the  focus of infection, there
were very few sick.  At a certain elevation and at a certain
distance from the southeast wind, which  was  the conductor
of the noxious exhalations, as is proved by the course of the 
19
epidemic, not an individual sickened who  had not been ex-
posed to  the causes affecting the lower part of the city.  In-
deed the  higher parts of Barcelona enjoyed a total exemption
from the disease.   These facts prove that the disease was a
true epidemic;  they are inexplicable on the supposition that
it was propagated by contagion.
  4. Certain facts  connected with the  origin, progress and
termination of this disease, afford  irresistible evidence that
it was an epidemic fever, and could not possibly be propa-
gated by contagion.   Thus it was common to see four, six,
or even eight individuals of the same family simultaneously
affected ; that is in the same day, the same  hour, the same
instant.   This might have arisen from an exposure to a pes-
tilential  air, it could not' have arisen from  contagion.  It
broke out  in numerous  points at once ; it  committed the
most  fearful ravages in certain  spots, while places  in the
closest proximity were entirely exempt  from its  attack.   In
a narrow street in Barcelona called  Calle de la Daguizea,
one hundred and thirty persons died; in a place within ten
yards of it not  one perished.  In Barcelonetta there were
two families which  resided  close  to  each other—they both
lived  about the middle  of the south side  of  Calla  Santa
Barbara—the houses were of the same size, plan and  struc-
ture.   The easternmost family consisted of six persons, they
kept a grocer's shop and were in constant communication with
the public—here not one was sick.  The westernmost family
consisted of ten members, they kept a wine and  liquor shop,
and were also in constant communication with the public—
here every one sickened and nine  died.   The grocer  whose
family did not suffer at all, was sheltered from the southeast
wind  ; the spirit merchant's family, every member of  which
suffered, was directly exposed to it.
  These  facts are in perfect harmony with the usual cause of
fever  in this country.  Of the fever in  Gibraltar, in  1813,
Mr. G-ardener, Surgeon to the Naval Hospital, observes that
the disease did  not spread from any focus, but broke  out in
fifty different places at once.   " The rise and progress of our
epidemics," says Mr. Amiel, "have never been traced  in a 
20
 satisfactory manner from  a  single point of contagion to a
 gradual number of individuals or families ;  and instead of
 creeping slowly from one district to another, cases have made
 their appearance  unconnected and scattered  at  different
 points; and in some instances it has spread with the rapid-
 ity of the electric  fluid, attacking  persons who had  never
 approached the sick  or any  assignable  cause  of conta-
 gion."
   Like  other epidemics, it was when the fever of Barcelona
 had acquired its greatest degree of extension, and produced
 its greatest mortality that it began notably to decline.  That
 day, as  has been stated, was on the 19th of October; on that
 day there died two  hundred and forty-six persons, on the 2d
 of November there died only ninety-eight; subsequently it
 diminished  in a regular  and progressive  manner until its
 total disappearance.
   When those who had contracted the fever in Barcelona re-
 moved into the country, whether  they died or recovered, not
 a single case occurred of the communication of the  malady,
 even  to their nearest relative, if the latter had not been in
 the city.   G-reat numbers of persons passed  the whole day in
 the capital who retired at night to their families, either in
 country houses or  in the nearest villages; in  no case did
 they communicate the disease to any individual.
   The danger,, so far from being in the direct ratio of inter-
 course with the sick, was in many instances  in  the  inverse
 ratio.   Whenever the hospitals were placed in healthy situ-
 ations, the attendants on the  sick, in  these establishments,
 enjoyed even a greater exemption from disease than  the in-
 habitants  of the town generally.  The average proportion of
 persons  who were sized, estimated upon  the whole  commu-
 nity, was  about one in seven.  In the Geneial Hospital, the
 proportion of those who sickened among the attendants was
 also one in seven ; in the Lazaretto of the Vice Queen of
 Peru, it was one in  eight; in the  Hospital of  the Seminoria,
 it  did not  exceed one  in thirty ; in the Lazaretto of Naza-
 reth, which was the receptacle of the worst cases, there were
thirty attendants upon the sick ; of these not one was seized. 
21
Surely this is evidence which no mind can resist that the dis-
ease was not contagious.
  Several families isolated themselves  in  their houses, and
employed the most exact precautions for avoiding communi-
cation with the sick;  but they did  not by any means pre-
serve  themselves from the malady.   Those who shut them-
selves up in good air, and who possessed  the  means of sur-
rounding themselves with the conveniences and comforts  of
life, were uniformly  exempt from  the disease ; those who
shut themselves up in the pestilential  atmosphere, and who
had not the means of rendering their condition comfortable,
were  sooner affected than those who mingled in indiscrimi-
nate  intercourse.  These facts  afford  the most irresistible
evidence that this fever is a true epidemic.  It conformed  in
every respect to the laws of epidemic diseases  ; it is without a
single character of a contagious disease.  So complete is this
evidence that it produced the fullest conviction in fifteen phy-
sicians who assembled from all parts of Spain and of Europe
to investigate the disease, and it produced a practical con-
viction in the Spanish Cortes, contrary to all their ancient
and deep-rooted  prejudices, notwithstanding the  fact that
they had so recently witnessed the  appalling extension and
the horrible mortality of the disease.  In the  United States,
Dr. Rush, who had been a warm advocate for the  doctrine
of the contagious nature of yellow fever, on  a  more patient
and strict examination of its phenomena and  history, became
convinced that he was  in  error, and with a magnanimity
which has but few parallels in the medical  profession, pro-
claimed to the world that he had thought and written  on
this very important subject  in a manner  calculated to mis-
lead.   " In the fouth volume,"  (Medical Enquiries and Ob-
servations,) says this celebrated  physician, "the reader will*'
find a retraction of the author's former  opinion of the yellow
fever  spreading by contagion.  He  begs  forgiveness of the
friends of science and /humanity, if the publication of that
opinion has had any influence in  increasing  the misery and
mortality attendant upon that disease.   Indeed, such  is the
pain he feels in recollecting that he ever entertained or prop-
« 
22
agated it, that it will long and perhaps always deprive him
of the pleasure he might otherwise have derived from a re-
view of his attempts to  fulfil  the  public  duties  of  his sta-
tion."   With such  evidence before us, it is impossible to re-
sist the conclusion that the yellow fever is  an epidemic and
not a contagious disease. 
r-