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A^icAlJoUiMi,, 



U.S. DEPARTMENT OF AGRICULTURE. 

BUREAU OF ANIMAL INDUSTKY. -^ G ~.h. 



SPECIAL REPORT 



ON THE 




AND PREVENTION OF SWINE 




RESULTS OF EXPERIMENTS 



CONDUCTED UNDER THE DIRECTION OF DR. D. E. SALMON, 
CHIEF OF THE BUREAU OF AiSilMAL INDUSTRY. 



BY 



THEOBALD S^ITH, Ph. B., M. D, 



PUBLISHED BY AUTHORITY OF THE SECKETARY OF AGRICULTURE. 









(., , - J o 

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(^f wov ^-.-^^ 



WASHINGTON": 

GOVERNMENT PRINTING OFFICE. 

1891. 




IB!: 



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V. ^ W ^ 



^377 
S66 



TABLE OF CONTENTS. 



Pago. 

Letter of traDsmittal 7 

InvestigatioDS concerniDg the natare and etiology of swine plague .--, 9 

Introductory - 9 

Brief description of the methods employed in the investigations 11 

Brief summary of the earlier investigations of swine plague (1886-1888) 19 

In Illinois 19 

Inlowa (1886) 2a 

In the District of Columbia 23 

In Maryland.. 27 

In Iowa (1888) 28 

Investigations of 1889-1890 31 

In the District of Columbia 31 

In New Jersey * 57 

Swine-plague bacteria, general characters , 85 

Eesistance to destructive agents 90 

Pathogenic action of swine-plague bacteria.... 93 

Effect on small animals 93 

The disease in swine as produced by the inoculation of cultures 97 

Swine plague as observed in epizootics 98 

Disease of the digestive tract in swine plague 102 

Attenuated swine-plague bacteria in sporadic cases of pneumonia, in septic 
diseases of swine, and in the upper air passages of healthy svrine and other 

domesticated animals 109 

Other investigations of swine plague 118 

American 118 

European 125 

Practical observations 133 

1. Conditions which may favor and oppose outbreaks 133 

2. Distribution and transmission of swine-plague bacteria 135 

3. Relation of hog cholera to swine plague 138 

4. Relation of swine plague to diseases of other domesticated animals 141 

5. Measures to be taken in the prevention of swine plague 145 

Conclusions 149 

Appendix. — ^The presence of septic bacteria probably identical with those of 

swine plague in the upper air passages of domestic animals other than 

swine, by Dr. V. A. Moore 151 

Description of plates 161 

3 



90OZ 



LIST OF ILLUSTRATIONS. 



Page. 

Plate I. Normal lungs of pig, inflated, lateral surface 163 

II. Same lungs, diaphragmatic surface 163 

III. Hepatization of lung with pleuritic exudate 163 

lY . Same lung with adherent portion of diaphragm 163 

V. Hepatization of lung with necrotic foci 163 

YI. Pneumonia, pleuritis, and pericarditis produced hy inoculation of 

swine-plague bacteria 163 

YII. Caseous degeneration of lungs in swine plague 163 

YIII. Caseous masses in lung tissue. Masses of exudate in large intestine. 163 

IX. Collapse and broncho-pneumonia , 163 

X. Pericarditis in swine plague 163 

XI. Swine-plague bacteria (highly magnified) 163 

XII. Swine-plague bacteria in cultures w..... .. 163 

6 






LETTER OF TRANSMITTAL. 



Washington, D. 0., July 20, 1891. 

BlE : I have the honor to submit herewith the second special report 
'upon the investigatious of infectious swine diseases. The first report 
dealt mainly with hog cholera, while tlie accompanying report is de- 
voted to swine plague. 

In this volume the investigations are reported in detail which have 
led up to a separation of swine plagne as an iudependeut disease from 
hog cholera. The difficulties surrounding investigatious of infections 
swine diseases have lieen very much increased by the frequent associa- 
tion of both hog cholera and awine plague in the same herd. This 
has necessitated frequent repetitions of investigations before positive 
results could be obtained. 

The importance of thoroughly scientific investigations of infections 
animal diseases is becoming more and itfore apparent, and, owing 
to the commercial interests at stake, the subject is now assuming an 
international character. Even though investigations of this nature 
do not at once suggest the means of dealing satisfactorily with such 
diseases, it is, nevertheless, essential that we should know as much as 
possible of the nature of every one of them within our boundaries if 
we expect to bring to bear upon them all the knowledge which is 
accumulating so rapidly in various parts of the civilized world. The 
investigations in this report prove the existence of a virulent swine 
disease due to specific bacteria and its identity with the disease of 
Sohweinegevche, prevalent in Germany, It also demonstrates the wide 
distribution of this class of bacteria, chiefly as varieties of feeble 
disease- producing power in the upi>er air passages of various domesti- 
cated animals. It is not improbable that this group of bacteria may, 
when exceptionally virulent, attack other domesticated animals, and 
indeed we know that tlie bacteria of at least one form of fowl cholera 
can not be distinguished from those of swine plague by the bacterio- 
logical methods now in use. In short, this group of bacteria which 
appears to have a world-wide diatribntion, may be considered ae very 
dangerous to our domesticated animals, and, consequently, the care 
with which they have been studied, more particularly with reference 
to their disease-producing properties, is fully justified. 

With the publication of this and the preceding volume the infcrtaar 
is given by which a diagnosis can be raaiie q5 Oat Xwo ^-Evac^^sA, 



8 

infectious diseases to which our swine are subject. The nature and 
cause of these diseases are made clear, and knowing these, we can 
apply the curative and preventive measures which the progress of 
medical science has made possible, or which future researches may 
show to be available. 

D. E. SALMOK, 
Chief of the Bureau of Animal Industry. 
.Hon. J. M. Rusk, 

Secretary of Agriculture. 



MNVESTIGATIONS CONCERNING THE NATURE AND ETIOLOGY 
OF SWINE PLAGUE. 



INTEODUCTOEY. 

Since 18S6 the bacteriological iovestigattons carried on in the labora- 
tory of the Bureau of Animal Indaatry on infectious swine diseases 
have revealed the existence of pathogenic bacteria differing markedly * 
from those cansing hog cholera. They preferably attack the chest 
organs of swine, the lungs, and scrouB membranes covering these vital 
organs. The difflcolty encountered from the beginning in obtaining a 
clear understanding of the action of these disease germs is the frequent 
mingling of hog cholera with this disease, which has been called swine 
plague. In some outbreaks only hog-cholera bacilli are detected, iu 
others only swineplagae bacteria, while in the majority of outbreaks 
thus far studied both bacteria are associated together. This condition 
is very likely due to their wide distribution over the couutry. 

The importance of swine plague bacteria ia not limited to swine dis- 
eases alone, for they belong to a group of bacteria which in various 
parts of the world have attacked other species, such as cattle, horses, 
game, and fowls, and the question whether there may not be a trans- 
mission of such diseases from one species of farm animals to another 
most not be lost sight of. 

The swioe-plague bacteria have been very carefully studied in view 
of their imi)ortauce, and attention has been giveu more directly to their 
pathogenic eifect on the smaller experimental animals, such as mice, 
rabbits, guinea-pigs, pigeons, and fowls, in order that a proper nnder- 
Btanding of their relative virulence conld be obtained. Investigations 
in various diseases have brought to light bacteria which, although iden- 
tical so far as we are able to determine, vary greatly in their virulence, 
and it seema now that the relative virulence or disease-producing power 
must be looked upon as the chief criterion of danger. Feeble virnlence 
signifies a feebly infectious localized disease. A high degree of virn- 
lence signifies the power to spread and perhaps to attack other species. 
This important factor of virulence can only bo measured by the inocula- 
tion of animals of various degrees of susceptibility. The great variation 
In the virulence of both swine-plague and hog-cholera baoilli has been 
r ■ demonstrated in this way, and when we come down to the lowest grades 





I 



ft 



tbe problem arises, can Bach varieties produce disease at all, aud are 
they not merely accideotally preseut T iu auawer to tliis gnestion cau 
not l)e given categorically at preseut, and its soUitioii will demand con- 
tinned, undivided attention to this subject of disease germs for some 
time to come, 

Another fact, the significance of which has been discussed in the 
text, is the existence of bacteria in the air passages of various domesti- 
cated animals during health, which are not distinguishable from swine- 
plagne bacteria excepting by feebler pathogenic eflfect. 

The question whether swine plague is an infections disease by itself, 
demanding the attention of the veteiiuarian, the agricuitnristj and the 
Government, was practically solved, though not absolutely demon- 
strated, by the investigations of 1887. The repeated attacks upon this 
work made it desirable to spend much more time than was actually 
necessary in the investigation of outbreaks as they came within Teach 
of facilities irom time to time, and now a large amount of material has 
been collected which fully confirms the position taken in 1887, that 
there are at least two swine diseases of an infectious character. These 
have very likely existed together for a long time, but a differentiation 
could only be eftfected by the advanced position of bacteriology and the 
ample means provided by the Government. 

The frequent association of hogcholera bacilli with swine-plagne 
bacteria has made it necessary to pay some attention to hog cholera as 
well. Theife iuveatigations are based on the facts already published 
on hog cholera aud the bacillus of that disease in the special report on 
hog cholera (1839). This report is therefore necessary to an under- 
standing of the contents of the present volume so far as the strictly 
experimental portion is concerned. 

It is to be hoped that these investigations will prove not only of ad- 
vantage in the protection of swine from disease, but will be a basis for 
the investigation of diseases of other domesticated animals due to this 
group of bacteria, which may appear at any time owing to the growing 
complexity of intercourse between differeut sections of the country, 
modificatious in the methods of stock-raising, etc. 

It must not be assumed that our kuowleilge of the etiology of swine 
diseases is complete even with the advances made thus far in swine 
plague and hog cholera. There are important questions with reference 
to both diseases which demand elucidation. Especially is it desirable 
to investigate those oatbreaka more carefully in which we find the ap- 
pearances of hog cholera without the bacilli in the internal organs. 
The complete mastery over a disease is only to be obtained by complete 
insight into its causes. If all the suggestions derived from scientific in- 
vestigations, conscientiously apphed, faO to prevent the appearance of 
a given disease it signifies that our iuforoiation is as yet incomplete, 
and that there are some still unknown channels through which the 
bacteria of such disease are distributed. 



11 

To deviso a proper plan for .an iutelligible preaentation of tbe inves- 
tigations and results wbicli will be satisfactory to those wbo are not 
itn mediately interested in tlie investigations, and simply desire to Icnow 
the deduGtions so as to be guided by tfaem, has been a difficult one, imJ 
has demanded the occasional repetition of statements. In general all 
those facta not necessary to an understanding of the text have been put 
into smaller type. All the investigations proper, including a detailed 
description of the various outbreaks, autopsy and bacteriological notes, 
test inoculations of swine and smaller animals, have been kept together 
under the respective outbreahs, while all essential information derived 
from these investigations and experiments is to be found in the subse- 
quent sections of the report. 

The contents, therefore, have been arranged in the following order: 

The methods of work are tirst described, followed by a brief review of 
earlier and a more detailed account of later investigatious. Then come 
a general description of the swine-plague 'bacteria, of their disease-pro- 
ducing power, and some facts showing the wide distribution of this 
group of bacteria among domesticated animals in a healthy condition. 
A chapter is also added, giving a brief account of the iuvestigation of 
others in this field. Lastly, all the results and practical observations 
which may be of value to the farmer are brought together. 

The writer acknowledges the continued assistance since 18S6 of Dr. 
F, L, Kllborne, veterinarian of the Experiment Station, who has had 
charge of the experimental animals, has assisted in many of the post 
mort«m examinations, and has perform ed the inoculations upon swine. 
In the laboratory. Dr. V. A. Moore has assisted, since 1888, in general 
pathological and bacteriological work. The special services of these 
gentlemen are also referred to in the text. 



BRIBF DESCRIPTION OP THE METHODS EMPLOTER IN THE INTES^ 
OATIOKS. 



'^ 



The difficulties that are met with in the investigation of infections 
swine diseases are not those usually encountered in bacteriological in- 
vestigations. In the first plaee outbreaks occur as a rule some distance 
from a laboratory. Yet the amount of bacteriological work demanded 
by each caae, in order that any conclusion may be reached, can not be 
done excepting in a well equipped laboratory. Heuce it has been our 
effisrt to transfer, if possible, cases of the disease to the Experiment 
Station, and also to keep* up the disease there by exposing fresh cases. 
In fact, only those investigatious carried on in this way can be regarded 
as complete, while cultivations made in the field are at best restricted 
to a few or only one organ, and plate cultures are out of the question. 

Another difficulty is due to the belated information which we obtain 
of any given outbreak. Usually from one-third to two-thirds of the 
herd have perished before the investigations are begun. This is anfor- 
^^[mate in awine plague, because the earliest caae% wc^. ^^ vo.^'fX. «»ia<a^^^ 



u 

factory from a bacteriological standpoint, since the swine-plagae bacteria 
are most easily demonstrated in such oases. It seems that the iiifectiou 
passes through a herd quite rapidly, and those animals which live loug- 
est have reached a stage of the disease in which the swine-plague 
bacteria may have entirely disappeared. 

A third difflcnlty to be contended with is the rapid death of the aai- 
mals, which makes a thorough examination of each animal impossible. 
The alternative before us is either to limit our examination to a certain 
number of organs in every animal, or else to examine a few very 
thoroughly. While we have endeavored to meet both demands, of ex- 
amining every animal, and also doing it as thoroughly as possible, we 
have but partially succeeded in this, owing to lack of facilities and 
assistance. The pathological changes differ so much from animal to 
animal, the extent of the organs involved varies to such a degree, that 
there is a great temptation to examine every animal in the hope that 
most information can be obtained in this way. 

The investigations consisted in watching the course of the disease in 
the infected auimalB, in post-mortem examinations of those that died, 
in microscopic examination of the diseased tissues, fresh and hardened, 
and ill bacteriological examination of a certain number of organs. The 
post-mortem examination included the various organs and tissues, with 
the exception of the brain and spinal cord, which were exposed in a 
very few cases only. The skin was first reflected from the thorax and 
abdomen, the abdomen carefully opened, and the spleen or a portion of 
it first removed with sterile instrumeuts and reserved for further ex- 
amination. From any fluid or exudate present a minute quantity was 
transferred to culture media by means of a platinum wire bent into 
a loop al>oat three to four millimetres in diameter and soldered into a 
glass rod. The thorax was next opened by removing the sternum, and 
from any effusion or exudate cultures were made at once. The vari- 
ous organs destined to be used for bacteriological examination were 
removed in whole or in part before being soiled. 

Portions of organs designed for microscopical examination were in 
part examined fresh by making sections with the razor, teasing, etc., 
in part hardened in 95 per cent, alcohol and infiltrated with paraffin 
before the sections were made. These were stained in different ways, 
chiefly in alum carmiue and in alkaline methylene blue (LolBer), which 
was found most satisfactory in bringing out the swiue-plague bacteria. 

The various cultures were made in the following manner: With a 
platinum spatula a small area of the surface of an organ was thoroughly 
scorched, and from the scorched area minnte particles of tissue were 
cut out with flamed scissors and forceps, the scorched layer being 
rejected. These particles were then transferred to various media for 
tube and plate cultures and also used for the inoculation of animals. 
Another mode of inoculating cultures used was to pierce the scorched 
area with a straight stiff platinum wire, which was then stirred about 



^^B in liqaefiei 
^^P only a mi 

I 



18 






in liqaefied media or rnlibed over the surface of agar. In this way 
only a minute trace of the parenchyma could be transferred, and it 
was only naed when bacteria were numerous enough to be detected 
under the microscope. lu the notes given with the various outbreaks 
the platinum loop aud wire mean respectively the looped wire and the 
straight wire. Note is merely made of this to indicate the difference in 
the quantity of material used to inoculate the culture media. 

The more usual method in vogue of disinfecting the external surface 
of organs by placing them iu a 5 per cent, solution of carbolic acid or 
a one-tonth per cent, solntion of mercuric chloride for a short time, 
then making several incisions in planes at right angles to oue another 
into the depth of the organ, was not employed, because the method 
already mentioned of scorching a small portion of the surface seemed 
safer and more satisfactory. When cultures were inoculated with 
blood this was done from the right ventricle while the heart was still 
in situ. The thin ventricular wall was scorched over a small area, 
then the edge of the spatula was used to burn through. The platinum 
wire or loop, or the glass pipette, if blood was to be collected, was 
inserted through the hole thus made. The same methods were employed 
in the esamiuation of the small experimental animals. 

For the cultivation of swine-plagne bacteria agar-agar aa usually 
prepared with bouiUon, peptone, and common salt, and the ordinary 
peptone bouillon, are the best media. In the earlier investigations 
nutrient gelatine was chiefly employed, but it was found that some 
varieties of swine-plague bacteria may refuse to multiply in it, hence 
it was discarded. In addition to plate cultures for the isolation of these 
bacteria the inclined surface of agar in tubes is of great service. In 
many cultures the colonies appeared completely isolated on the agar 
surface, thus enabling us to start from single colonies when plate cul- 
tures had not been prepared at the same time. 

For the inoculation of smaller animals with bacteria from cultures 
two methods were employed : (1) A small pocket was made in the sub- 
cutis by an incision through the skin with sterilized scissors and a loop 
of the growth rubbed into this pocket ; (2) liquid cultures were jire- 
pared by inoculating peptone bouillon and allowing theliquid to become 
clouded in the thermostat or by transferring the growth from agar 
tabes into sterile bouillon or water and making a suspension. The 
liquid was then ii^ected with a hypodermic syringe into the sub- 
outaneous tissue or into a vein. The hypodermic syringes used were of 
the ordinary pattern, since the various others devised, such as the Koch 
syringe and the asbestos-packed syringe, were found leaky and ine£Q- 
cient aud did not enable us to inject a definite quantity with accuracy. 
In this investigation these syringes could the more easily be dispensed 
with, since both swine-plague and hog-cholera bacteria arc sporeless aud 
killed by disinfectants in very dilute solutions. The syringes and 
needles were disinfected both before and after use by filling them with 



J 



A per cent, carbolic acid and allowing this toreruaiu forl5or20aiinnte8. 
The acid was then removeii with boiling water. Great care was taken 
that no fluid passed beyond the piston. If it did the syringe was taken 
apart and the parts immersed in 6 per cent, carlxilic acid. While this 
method of making injections may seem theoretically objectionable, It 
has ueyertheless at no time proved the source of any accidental infe«- 
tiou. This method is not applicable, however, to bacteria which pro- 
duce spores, or which prove very resistant to disinfectants, sach as 
anthrax and tuberculosis. In general syringes were dispensed with 
and the first method employed when the accurate measurement of the 
quantity of virus to be injected was not essential. 

The technical difaenlties snrronuding the problem of the causation 
of swine diseases are mainly due to the intermingling of two diseases, 
bog cholera and swine plague. As this problem will be discussed fur- 
ther on, only those points need be considered here which involve the 
methods employed. The important question to be decided in every 
outbreak is whether one or both kinds of bacteria are present. This 
can only be determined by bacteriological investigation. It is evident 
that to examine every organ of every pig bacteriologicaliy is a task of 
enormous dimensions, hence the simplest reliable method mnst be em- 
ployed. At flrst thought it would seem sufficient to make plate cultures 
trova the various organs and examine the colonies as they develop. 
There are, however, objections to this method taken alone. Certain 
varieties of swine plague bacteria, especially the most virulent, do not 
as a rule grow in gelatine, while on agar the colonies of bog cholera can 
not be distinguished positively from those of swine plague, unless the 
bacteria composing these colonies are examined. For a rapid and reli- 
able determination of the presence or absence of these two kinds of 
bacteria, I have found in addition agar and bouillon tube cultures nec- 
essary. The motile hog-cholera bacilli are detected at once in the 
bouillon and in the condensation water of the inclined agar cultures. 
Such cultures may then be plated, and fresh cultures of the hog-cholera 
bacilli and the swine-plague bacteria obtained by inoculating from 
isolated colonies. These cultures are then in condition to be tested oil 
smaller animals to make the diagnosis complete. While it is desirable 
that when both kinds of bacteria are present they should be isolated 
from as many animals as possible, it is obvious that the presence of 
virulent hog-cholera bacilli in a single animal of a herd leads to the 
inference that they are most likely present in all the remaining diseased 
animals. 

The detection of swine-plague bacteria in liquid cultures containing 
hog-cholera bacilli is, as a rule, not difficult. The best method consists 
in the examination of the liquid unstained in a drop suspended from 
the under surface of a cover-glass resting on the margins of a cell on 
or iu the slide. The most convenient cell I have found to bo a thin 
glass ring fastened to the slide with Canada balsam, A little glycerin 



J 




15 

is placed on the ring so that when the cover glass with the drop on it 
is inverted and laid on the ring the immersion lens will not draw it up, 

The hog-cholera bacilli are readily detected iu this drop by their 
motion." If the border of the drop be examiued, the two kinds of bac- 
teria may then be distingaisbeil by a slight difl'erence in size iu favor 
of the hog-cholera bacilli. When the growth from the condensation 
water of agar cultures is to be examined, it must be diluted with bouil- 
lon or sterile water kept preferably in tubes, just as the bouillon is, in 
small quantities. The examination of cultures in this manner can not 
be dispensed with in the study of these diseases. When the presence 
of one or both kinds of bacteria has been positively determined, I find 
staining of very little value in subsequent work and simply examine 
fluids as described. When colonies are to be examined a drop of bouil- 
lon or water in which a trace of growth is stirred np is, of course, nec- 
essary. 

Another advantage of the bouillon and the condensation water of agar 
tubes rests upon the fact that motile bacteria do not always become 
active at once when transferred ftom agar or gelatine into liquids for 
microscopical examination. Hence their motility may be entirely over- 
looked unless they are examined after having multii»lied in liquids for 
some honrs at least. 

It should likewise be borne in mind that the colonies of a few bacteria 
in a bit of tissue or drop of effusion from the diseased body may escape 
attention on a plate when many other colonies are present, and that 
they may be entirely lost on the second or third plate. In bonillon, 
however, both kinds of bacteria have for a time the same opportunities 
for multiplication, and both may be detected on the following ijay, 
though there may have been originally a great difl'erence in the num- 
bers introduced. "While agar plates have occasionally failed to dem- 
onstrate the presence of certain baeteria, owing either to a failure to 
multiply or to the rapid growth of other bacteria, or to rapid drying ont 
of the agar layer, bouillon and agar tube cultures maile at the same 
time have furnished the desired information. 

Iu order to detect both kinds of bacteria it is therefore essential that 
bouillon and inclined agar iu tubes be used with agar plates. The 
method pursued in the investigations detailed in full in this report was 
always to prepare plates from lungs. When there was no time for the 
preparation of plates from other organs, such as spleen, liver, and kid- 
neys, tubes of bouillon and agar were used in place of them, and, if 
necessary, plates were prepared from these. 

A minor difficulty, but one which may prove of more serious conse- 
quence to beginners, is the frequent encountering of bacteria other 
than those producing the disease in the organs of diseased swine. A 
perusal of the bacteriological observations in this report will show how 
much time has to be spent in isolating these bacteria and determiu- 

* See Bpeuial Ro[)c)rt uu Hog Chulora, 18SD, for the cliaractera of these bacilli. 



i 



I 

i 



16 

ing what relation they bear to the disease. Many of tbem can eT^nt- ' 
ually be traced to the intestines where they commonly vegetate. Their 
presence in the internal organs may be accounted for by the extensive 
lesions in lungs and intestines which serve as entrances into the blood. 
This presence of strange bacteria has also been observed in other infec- 
tious diseases by other observers, and attention has been culled to it in 
connection with hog cholera in the special report on that malady, p. 58. 

The detection of these foreign bacteria has been in large part due to 
the aae of bouillon. As they are usnally present in very small numbers 
their colonies on plates might easily be overlooked or attributed to 
accidental infection. They would appear only on the first plate among 
large numbers of other colonies and most likely be overlooked, since 
the development of colonies on crowded plates is limited, and they fee- 
qaently fait to show any special features unless they have time and 
opportunity to expand. This is true of gelatine and particularly so of 
agar, on which colonies show, at best, few differences. When bouillon 
is inoculated all bacteria have for a time equal opportunities to develop, 
as stated above, and they at once thrnst themselves upon our attention. 
Such mixed cultures have been and are still styled contaminated by 
those who fail to see their real siguihcanue. Such criticisms may, 
however, be safely left to take care of themselves at the present time. 

As an illustration of the foregoing, I have frequently found in the bot- 
tom of bouillon tubes into which a bit of tissue had been introduced 
large spore-bearing bacilli, which have been referred to in the various 
reports as "anaSrobic," "post-mortem" bacilli. These bacilli do not 
develop in fresh cultures, nor would they appear on plates. The bot- 
tom of the culture liquid and the bit of tissue furnish for the time a 
suitable soil.* 

The use of animals in the isolation of bacteria is of great value iu 
swine diseases. Eabbits are peculiarly susceptible to swine-plague bac- 
teria. Inoculated with the more virulent varieties they die within 20 
hours, and the inoculated bacteria can be obtained from the various 
organs. Frequently when cultures failed to determine the presence of 
these bacteria in tissues rabbit inoculation was still successful. When 
a mixed outbreak is under examination it is evideut that since rabbits 
do not succumb to minute doses of hog-cholera bacilli in less than 7 
days, the rabbits will die of swine plague first and the hog-cholera 
bacilli will not be obtained from their organs. There are, however, at- 
tenuated varieties of swine-plague bacteria frequently encountered in 
mixed outbreaks which prove fatal to rabbits in from 3 to 10 days. In 
these cases when pure cultures are inoculated there is more or less sup- 
purative destruction of the subcutis starting from the point of inoc- , 
ulation, while the internal organs are quit« free from changes and . 
bacteria also. In such protracted cases, provided both kinds of bacte- 

* For a, simple method of ciillivfttiug snch bacteria in 
for anaetobeB, see fooC-aoto, p. til. 




17 

ria were originally present in the tissue iaoculated, both kinds may ap- 
jjear in the rabbit cultures, or only the hog-cholera bacilli may have 
become disseminated through the body, while the swiue-plague bacteria 
may be limited to the inoculated locality. Since hog-cholera baoilli do 
not produce much local intlammation, whenever this is extensive in 
rabbits inoculated directly from the pig, it is pretty certain that swine- 
plague bacteria and perhaps other still unknown bacteria may have 
caused it and should be looked for. 

Babbit inoculation may thus prove very serviceable, bnt the post- 
mortem appearances must be carefully interpreted in connection with 
the bacteriological observations. In any case they rarely bring to light 
hog-cholera bacilli when the inoculated animal succumbs to swine plague 
before the fourth or fifth daj'. 

A few words are necessary to define some of the anatomical terms 
used in the autopsy notes, inasmuch as a thorough description of the 
visceral anatomy of the domesticated animals has not yet been made. 
Since the lesions are confined chiefly to the lungs and intestines our 
remarks will be conhned to these organs, 

When inflftted through the trachea after theaterniiin is remoToiI, aod while the lungs 
are Btill in their uatnral position in the thoracic cavity, it will be observed that the 
Borface resting against the riba laterally is the mnat extensive. That aorfaoe rest- 
ing upon the diaphragm oomea next, while the ventral aspect is the amallest. (See 
Plates I, n.) The right long ia made up of four lobes, the left has only three. (In 
text- books on anatomy the left inng ia coDsiderod as being made up of only two.) 

In both there ia a large principal lobe resting a])On the diaphragm and agaiaat the 
adjacent thoracic wall. This lobe forms the major part of each Inug. The remainder, 
ocoupjing the anterior (or oophalio) portion of the cavity, is made np of two small 
lobes, one extending ventrally (or downward in the standing position of the animal) 
and in the expanded state covering the heart laterally, the other extending towards 
the head and overlapping the base of the heart. These email lobes may bo denomi- 
nated the ventral and cephalic lohes, respectively. The right cephalic lobe is longer 
and more distinct from the ventral lobe than the corresponding left oephulic. 
Wedged in between the two principal lobes and resting on the diaphragm ia a small 
lolie, pyramidal, belonging to the right lung (azygos or median lobe). Thiatobe rests 
on the left, against the mediastinal membrane, and on the right it is separated from 
the right principal lobe by a fold of the pleura passing from the veutral thorucic wall 
to inclose the inferior vena cava. This small lohe ia almost completely abut off, there- 
fere, &om the other lobes by folda of the pleura. 

When the trachea and its branches have been examined it is easier to understand 
this diviaion into lobea. The trachea divtilea iu the thorax into two principal 
branches or bronchi. Tbeae bronchi paaa into the principal lobes, straight to 
the caudal border, giving off a number of small branches along their course. Very 
neat the place of bifurcation the left hronohns gives off a large branch, which rami- 
fies in the substance of the left ventral lobe. Prom this branch another goes 1« the 
cephalic lobe. In some lungs the branches of these two lobes arise together from a 
very abort, acarculy perceptible trunk, and are of nearly equal size. The branchial 
snpply of the right lung ditfera materially from lb at of the left. About 2 centimetres 
from the bifurcation the trachea gives off a small bronchna, which suppliea the right 
cephalic lobe exclusively. At the hifnrcation the right bronchus aenda a short 
branch to the amall median or azygoa lobe and one to the ventral lobe, 

^ The m^or portion of the large intentiueof the pig consiataot b^uV'^'^a-^''^':^'"'^'^'^ 

L 1614 2 



18 

18 coiled upon itself somewhat like a watch spring. The csBcnm is boond down to 
the dorsal wall of the abdominal cavity on the right side. Similarly the rectum and 
a small portion of adjacent colon is fastened down by peritoneal folds. If, starting 
from csBcnm and rectum as fixed points, the eutire large intestine be folded on itself 
at the middle point of its length and the whole coiled up, beginning at this point as 
the free central end, we have imitated the general arrangement of the large intestine 
in the abdomen. The coiled part is loosely bound together and readily movable in 
the abdomen. As regards the dimensions the following measurements are taken from 
a male pig about 7 months old, and 39 inches long from the tip of snout to root of tail. 
The intestine was distented with normal feces : 1, ctecum, extending from closed end 
to ileo-csBcal valve, 7^ Inches long ; 2, from valve to duplicature or bend in the center 
of the coil, 5 feet ; 3, from the latter point to anus, 6 feet. It will be noticed that the 
folding takes place in the middle of the entire length of the large intestine. 

In the description of the regions the duplicature is a convenient point at which to 
distinguish the upper from the lower colon. Where the rectum begins it would be diffi- 
cult to determine without careful anatomical observations. Provisionally, its limit 
if determined by its old original signification may be placed at eight to twelve inches 
from the external opening or anus. 

In examining the large intestine it is best to begin the separation at the fold or 
bend in the center of the coil and continue until the caecum and lower colon are 
reached. The caecum is easily removed with the small intestine attached. The lower 
colon is associated with the duodenum in the same mesentery and is crossed by it. 
Care must be taken not to injure either tube at this point in attempting to separate 
them. In beginning it is best to tie a string around the tube at the flexure as a 
landmark for future reference. 

The writer has used, apparently without discrimiDatioD, the English 
and the metric system of weights and measures. It will be noticed, 
however, that in the more strictly scientific part of the work only the 
metric system is used, while in those portions which may be interesting 
to a wider circle the English system is substituted. 



\ 



BRIEF SUMMARY OF EARLIER INVE^TIfiATlONS— i886-'88. 



I. 



During the sammer of 1880 the writer made a nnmber of post-mortom 
exainiDations of diseased pigs iu Illinois, t for ttie purpose of identifying, 
if possible, the swine diseases exisling in the Western States with the 
disease of hog cholera {or swine plagne aa it was then denominated), 
under observation since Jfovember, 1885, on the Experiment Station 
near Washington. It will be remembered that the hog-uholera bacillus 
was discovered in November of 1885, and carefully studied as to its j 
mori>hologic3l and pathogenic characters. 

The post-mortem examinations were made in the field, the spleen 
removed, placed in a sterilized bottle, and the cultnres made either im- 
mediately or several hours later, indoors. During the first visit to 
Illiuois in July, 1886, pigs were examined in Marion, Champaigu, and 
Henry Counties. Insomecasesthe lungs were diseased. In most cases 
the intestines were more or less ecchymosed, while ulcers or indurations 
of the mucous membrane were rare. What waa most surprising, how- 
ever, waa the absence of any bacteria in the spleen of seven out of 
eight animals examined. In the eighth case there was considerable 
pneumonia associated with pigmentation of the mucosa in the large " 
intestines. The culture from the spleen contained two species of bac- 
teria, the bacillus coli communis, a common inhabitant of the digestive 
tract of the pig and other domesticated animals, and a small, non-motile 
bacterium which possessed pathogenic properties as the inoculations 
made at that time distinctly demonstrated. These bacteria were isolated 
by inoculating a rabbit subcutaneously with a bouillon culture contain- 
ing both kinds of bacteria. The rabbit died in 7 days with exten- 
sive infiammatiou of the subcutaneous tissue starting from the point of 
inoculation. Cultures from the spleen, liver, and blood contained only 
one form, the oval non-motile bacterium. A second rabbit, which re- 
ceived one-sixth cubic centimetre of a pure bouillon enlture of these 
bacteria under the skin, died in 3 days with beginning peritonitis. Two 
mice,inoculatedin the same manner, died respectively 1 and 2 days after 
inoculation. 






Alreud.y published in detuil iu vaiiuuH rbportaof tlie D»pnrLLueQbo< k'gfvt^^^^x^. ' 
Keimrt of the Bureau of Auimal ludusWs for lH«ft, p. 16. 




20 

Mach time was spent in studying the motile bacillna, owing to ite 
euper&cial resemblance to liog-cholera bacilli. Any one familiar with 
intestinal bacteria will, I tbink, at once concede, after reading tlie de- 
Bcription on page 78 of the report referred to, that this was the bacillus 
eoli. The peculiar expauding and rapid growth on gelatine, the coagu- 
latioQ of milk, the ofl'enaive, putrescent odor of the cultures, are prop- 
erties wliich do not belong to hog cholera bacilli. Moreover there was 
no manifestation of any pathogenic power. The small non-motile 
bacteria were identical with those named throughout this report as 
Bwiue-plague bacteria. 

II. 

Several months later the writer, having found the information ob- 
tained on this jouruey quite different from what was expected, under- 
took another journey in the same State.* As usual the various re- 
ports of swine disease found in the papers vanished before the writer's 
approach, aud after much search a herd was found near Sodorus, 
Champaign County, in which a number of animals had already perished 
and some were very sick. Two of the latter were hilled. In No. 1 
there were extensive pneumonia and some large ulcers in the large in- 
testine. In No. 2 there were the same pneumonia, a very large spleen, 
and one ulcer on the valve in the large intestine. Various cultures 
were made at the time and blood was collected in piiiettes which were 
sealed iu the flame. The result of the bacteriological examination was 
briefly as follows: 

From No. 1; The spleen contained only hogcholera bacteria. The 
blood (first pipette) hog-cholera bacteria and streptococci. The blood 
(second pipette) contained only swine-plague bacteria. 

From No. 2: The spleen, blood, and pleural cavity each contained 
swine- plague bacteria. 

Sections of tbe lung tissue of No. 2, hardened iu alcohol, showed large 
numbers of swiue-plague bacteria in the alveoli. 

"With swine-plague bacteria from the pleural tube cultures of pig No. 
2 a considerable number of inoculations were made upon smaller aui- 
mals to determine their pathogenic power as compared with the swiue- 
plague bacteria already found. The inoculatiouB were made by inject- 
ing deflnite quantities of bouillon cultures which bad been inoculated 
from single colonies on gelatine plates. 

One mouan, une-eightii ouLic centimetre anbcutaneonslf, dies in 48 hours. 
One moaae, tlirtte-aixtneaths cubic ceDtimetre suboDtaneoualj', diea ii 
One mouBe, oue-twelfth cnbio oeatimetre BubcutanBouBlj, dies in 2 daya. 
One moaae, one-twelfth oabic centimetre Bobcutaueously, dies in 6 da^s. 

In these animals there were no marked lesions. In some tbe baoterfa I 
injected were present in large numbers in the various organs ; in others 
they were very scarce. 

'L. c, p. 79. 



One rabbit, < 
One rabbit, t 
One rnlibit, t 



^-eigbth oobic oentlmetre anbcataneonaly, dte» 
e-fonrtb cribie aentimetre anbeiitaueoualy, diaH i 
j-eigbtb uubie oeatimetre Babcataneously, dies i 




5 days. 
3 ii»ys. 



In the rabbits at the place of inoculation the subcutia waa mnch 
tbitikened by purulent infiltration, and tbere waa more or less bemor- 
rbagic and exudative peritouitis. In tbe exudate tlie injected baeteria 
were very abundant. 

One pigeon, one-half cubic centitaetre sabaataneonsly, diag in 3 days. 
One pigeon, Ihree-fourtba cable oeDtimetre subcataueonsly, diea ia 4 days. 

At the place of tbe inoculation tbe muscular tissn© more or less 
uecrosed. Bacteria not detected in the internal organs. 

Que gninea-pig, ODO-fourtbs onbic centimetre aQboutaneouBly, dies in 8 days with 
Blight local cbangea and exudative peritonitia and pEeuntis. 

Que fowl, on a-balf cubic centimetre anbcutaueoualy, diee in 5 days. 

One fowl, 1 cubic eentiraeti-e subcutaneonsiy, recovered. 

In both there was exteueive aeoroais of the pectural niuacle at the place of iaocn- 
Intiou. 

The following animals were inoculated by rubbing into the subca- 
taneous tissue tbrougb an incision a loop dipped into a gelatine cul- 

tnre: 

One galuea-pig (abdomen) diea in 5 days; aubcutauooua lesion very ezteiisivo. 

One guiuea-pig (abdo:aen) diea in B days; eubcutaneouH lesiou very «(xteaaive. 

One mouHe (root of tall) diee iu 3 days. 

One mouse (root of tail) diea in 4 daya. 

One rabbit (ear) dies in 9 days ; eitenaive subcntaaeous lesiona. 

Two pigeons (breast) remain well. 

One fowl (breast) remains well. 

From cultures of the swiue-plagne bacteria derived from the blood 
of pig No, 1 two rabbits were inoculated to see if the bacteria from 
both cases were identical. 

One rabbit received one twenty-fourth cubic centimetre bouillon oultnre; died in 

3 dajB. 

One rabbit received a loop of gelatine culture ; died in 10 dayn, 

Iu both there was much local inQammatton in the subcutie and peritonitis. 

Witb cultures of the swine-plague bacteria from these two sources a 

number of pigs were inoculated as indicated in tbe t^ble : 



Pias, 


Date of iQ. 


ass s.™or-i.... 


Remarks. 




."•'J.'.':.'.-. 

Oct. B0.18S6 
oVt. ijigM 

NoV°lB,'iMi' 


/I 

y 

-1' 




DIee <n IS Unye. 

Dm, in 10 days, genCTollwd jaun Jioe. 

Uiea in 58 da; B. 














s-s 




BI^IISm^^U^'"""'"*" 






DI««lDSdajB^ jaandlae. 






No. 376 


....do 


DiemalldajB; Jiuudtce. 



22 

It will be seen that of these ten pigs eight were inoculated subcu- 
taneously with doses ranging from 2^ to 5 cubic centimetres of a bouil- 
lon culture. Two died from I to 2 months after inoculation, the remain- 
ing six in from 7 to 18 days thereafter with a peculiar disease of the 
liver and generalized jaundice. 

Two inoculated into the lung tissue through the right chest wall re- 
mained unaffected. 

The liver in these cases was greatly enlarged and so firm that when 
removed from the body there was no change of form. There was no 
obstruction to the flow of bile in the bile ducts. The disease of the 
liver tissue itself was shown in sections of cases 289 and 375 to be due 
to inflammatory foci within the lobules. In some of these foci the pa- 
renchyma cells were still visible, but very feebly stained 5 the trabecular 
arrangement was destroyed; the nuclei of the cells v^ry much shriveled 
or absent. In other foci the parenchyma was replaced by numerous 
round cells. From these observations it would seem that the disease 
consisted of necrosis of a mass of hepatic cells followed by round cell 
infiltration. These foci varied in size from one-eighth to one-half the 
area of the lobule. Almost every lobule was affected, either several 
small areas or one large area of disease being present in each, situated 
usually near the periphery. In Ko. 375 there was also very extensive 
cellular infiltration beneath the capsule.* 

That the disease was induced by the inoculation can not be very well 
denied in view of the facts in the case. The animals used were from 
four different lots purchased from four different owners.t No other 
animal in these lots died with these lesions of the liver. The inocula- 
tions must, therefore, be considered as the direct cause of the fatal 
result. 

These experiments are in so far remarkable as future subcutaneous 
inoculations with swine-plague bacteria from other sources, with one 
exception, produced no effect. I have not observed this disease since 
the time these experiments were made. The only explanation which 
can be made is that these varieties of swine-plague bacteria had a 
slightly different pathogenic power which manifested itself in the man- 
ner described. 

* Much ill-considered criticism has been leveled at these experiments and results 
by F. S. Billings, and they are, therefore^ presented again simply to show the im- 
founded character of these criticisms. WhUe the term cirrhosis used in the earlier 
reports may not have exactly expressed the diseased condition of the liver, it should 
also be remembered that the field of comparative pathology is not sufficiently devel- 
oped to aid us in choosing terms or in finding certain diseases already described and 
named. 

tNos. 287-294, bought June 1, 1886, when 8 weeks old, from Mr. M. ; Nos. 329-335, 
bought Aug. 27, 1886, when 8 weeks old, from Mr. B. ; Nos. 363-367, bought Oct. 18, 
1886, when 8 weeks old, from Mr. J. ; Nos. 368-382, bought Oct. 18, 1886, when 8 
weeks old, from Mr. J. F. 




III. 

Toward the close of 1886* Dr. Paaren sent to the Bnroau portions of 
lungs from Corro Gordo Oouiity, Iowa, These portions indicated con- 
solidation of the liing tissue with necrotic foci and exudative pleuritis. 
By JDocuIation into mice and rabbits awine-plague bacteria were ob- 
taiued, whicli, reinoculated iu pure culture, produced death within 24 
hours. The bacteria, very abundant iu the iuternal organa, showed 
tliatinotly the polar staiu.t They did uot difi'er in any respect from the 
bacteria found iu Illinois, excepting in their greater virulence on the 
smaller experimental animals. Two pigs inoculated subcntaneously 
^ritli 5 cubic centimetres each did not manifest any sigua of disease. 



B IV.- 

Iq February of 1887 an outbreak of swine disease came under obser- 
vation whicli showed conclusively the transmissibility of the lung dis- 
ease and the bacteria which areihe canse, 

The disease was associated in every case with pneumonia and pleuritis 
of a more or leas severe character. In the course of the disease casea- 
tion of the involved lung tissue was frequently observed. Intestinal 
leaioua of a kind hitherto observed but once before| were present in the 
earlier cases. These investigationa have been criticised by P. S. Bil- 
lings, if his statements deserve the name of criticism, because, in addi- 
tion to the awine-plague bacteria found in abuofit every case, bog-cholera 
bacilli were detected in the later cases. It is difBcult to discover from 
bis atatementa which of the two bacteria he objecta to. His own report 
leaves as wholly in the dark which kind he himself has found in Ne- 
braska, owing to the ambiguona manner in which the bacteria fonud by 
him have been described. We may therefore pass over these criticisms 
and briefly sammarize the investigationa§ which have since been con- 
firmed by much more extended onea, 

On January 31 a small number of pigs were purchased from a farm 
adjoining tbe Experiment Station for the purpose of testing the ( 
of different cathartics on the healthy pig. The animals had been pur- 
chased from this farm because no disease had existed there for se" 
years. These pigs (Noa. 402-406, inclusive) were put in a pen by them- 
selves. On the following day one (No. 400) was found dead with exten- 
sive ulceration of the large intestine, but no lung disease. This occur- 
rence of course spoiled the entire experiment as planned. The disease 
was regarded aa hog cholera by me, although 1 did not examine tbe 

•L.C.,p,!»2. 

I For tlio muaniug of tliis espreBsion, sw p-S-"'. 
t Report of the Bareaii for 1886, p. &>. 

^ For a fall aocouotof the antopay uotosaiid bucteriolngLKiil uxamioation, Bceroport 
rtlie Barsan for 1SS7, p. 86. 



I 

I 



I 



I 



animal or make cnltnres, being engaged iu other work at tlie timo. An- 
otlicr fact which led to ihe sniiposition that this disease was different 
from the ditioane which appeared later in the other aoimalB of this lot 
was told by the owner. Nos. 405 and 400 were the only pigs which had 
not been coiiQaed in i>ens, and which, therefore, may have been ex- 
posed to infection on the farm which did not reach tlie penned animals. 
At the time No. iOli died (February 1), the other animals appeared 
well. Some of these were distribnted into small pens by theinselvee 
and fed different doses of cathartics. Meanwhile no other auJmal of 
this lot died until 15 days lat«r, when 403 died. The following table 
gives information concerning the rest: 



'"•■ "£:: 






E^n. 


,. 


If<).4ai> Feb. 8-.. 


V6uli«llulK»oiluii 
EiIenslTe pnenmau 


esitlasniu'il 


E\B3 


olUrgelnUtstloe. 







As regards the bacteriological examination the following may be said: 

No. 40S, None made liecanae diaease eiipposoil to be hog cbolora. 
No. 403. None made for same reosoii. 

No, 405. 8wiiie-plagne bacteria fonnd in Iniigrt^ otliec organs not oxamioed. 
No. 402. Bouillon cultures made from pleural shredH, t<plceu, liver, siid blood. 
Gelatine cultures made iiom blood and Utoc. 

Nearly all the cultures from No. 402 contained a large spore-bearing 
bacillus which I have frequently found since then in cases of swine dis- 
ease having hemorrhagic lesions. Cultures from the liver and blood 
contained also swine-plague bacteria which were isolated by rabbit 
inoculation. 

It will be noticed that in the later cases, Nos, 403, 405, and 402, the 
large intestine was the seat of a pecnliarjy intense inflammation, ac- 
companied by the exudation of circumscribed masses of fibrin easily 
lifted away from the mucosa, leaving a paler, slightly depressed spot 
showing no necrosis of tissne. In the rectum this exudate formed a 
continuous sheet also easily removable. 

It might be claimed that the feeding of a dose of aloes or salts may 
have caused this peculiar intestinal iufiammation. This claim, however, 
is effectually dispo.sed of by case No. 407. This animal, one of the same 
herd, bad not been taken from the neighboring farm. It was found 
dead February 22, and brought to the Station for examination. The 
notes of this case are reproduced because it must be oonstdered the 
most trustworthy of all. 

No. 407. Pig of medinm size, white; skin of abdomen, oteit, neck, and back deeply 
reddened. Fat alnmdant, sliglitly roddunail along the linea alba. Superfici^ 
inguinal glands si Ightl; enlarged ; spleeu dotted with elevated blood-red pointe.* 




Stomacb and duoileuum uoriual, fha latter bite-staiued. In ilenm Pejer'a [iiitcheH 
are visible as gmnpsof Boiall, dack dots ; no strelling. Mucosa of cfecuui and upper 
colon of a dirty btackjah :^o1o^, probably pigmentud. A few bnjmatoniata beusath 
mucosa. BeBldea tbo diffuse pigmentation tlie mncosa ia sprinkled with isolated oc 
confluent maaaes, abont one-oifihtli to one-fourth iuch in diameter, of a dirty grayish- 
yellow color, loosely adherent to the membrane. When pulled away a slightly 
depressed surface is exposed. Much of this iiiueit cau be easily removed by simply 
moving the scalpel over it. There are several nloera in the cieoam with decided loss 
of snbstiiiice. The patch of mucous glands at the base of the valve is also converted 
into an ulcerated mass. Lymphatic glands in abdomen slightly swoUen and red- 
dened. Kidneys deeply reddened to tips of papillie. 

On opening the thorax the lungs did not collapse, and a rather disagreeable odor 
was perceived. As in No. 405, the ventral and cephalic lobes of both lungs were 
consolidated. The hepatized regions were very bard to the touch, bright red, with 
yellowish points sprinkled in regularly, (See Plates ui and iv.) The right lung 
was adherent to cheat wall over the hepatized portion, A whitish, spongy mem- 
brane was interposed, about one-eighth to one-fonrth inch thick, inclosing a small 
quantity of tarbid liquid. On removing the lungs the membrane remained adherent 



j 



to the pulmonary pleura, and was removed with difficulty. A portion of thu dia- | 

phtagm was also firmly attached. The left lung adhered firmly to the chest wall in } 

two places, where it was consolidated. The costal plenra was deeply I'cddened, | 

owing to the injection of a close uct-woik of min'iite vessels. Trachea and bronchi I 

tilled with whitish foam. 

On section, the consolidated region ia sharply but irregularly marked off from the 'i 

normal tissue, very oonaistent and slightly elevated. The color variea from a bright I 

red to a grayish red. In all, minute grayish points are present one-twelfth inch in i 

diameter, about the same distance apart, and of a hazy outline. The smaller bronchi 
are filled with a purulent fluid. In the surrounding lobutes in which the disease is J 

more advanced the interlobular tissue is distended with a serous infiltration ; the I 

large vessels are filled with very oonsisteni dark clots. Heart rather large, pericar- ' 

dium free ; right auricle, ventricle, and large veins distended with clots ; small I 

white clot in left ventricle. 

Microscopic examination of the lung tissue in cover-glass preparations shows the < 

presence of numerous bacteria with the polar stain in recent lesions ; in older ones 
they are rare, Other forma are present, bnt only In small numbers. The plenral 
exudate was made np of roands cells, bound together by bundles of fibrin ; it con- 
tains few bacteria. 

In transverse sections of the large intestine, where a mass of exudate ia still 
attached, tfae muscular and submucous layers are intact, if we escept a slight cellu- 
lar inliltration near the base of the crypts. The mncous layer, however, is consider- 
ably changed. The surface epithelium, including a portion of the crypts of Lieber- 
kiihn, is no longer distinguishable, but merges without demarcation into an exudate 
several millimetres thick, consisting of leucocytes imbedded in a mesh-work of fibrin, 
the whole refusiiifi to stain. 

Purs ouUiiresof swine-plague bacteria in tubea of gelatine were obtained from the 
plenral exudate. In each needle track a large number of colonies developed, A 
piece of false membrane gave the same result. Cover-glass preparations from spleen 
and liver wore negative. Two tubes of beef infusion into which bits of spleen had 
been dropped remained sterile. Two similar cultures from the liver contained each 
a large bacillus, evidently of post-mortem growth. The blood from the heart was 
also free from bacteria, for two tubes of gelatine, each iuoculated six or seven times 
with blood, did not develop a single colony. 

Arabbit inoculated in the ear with a hit of Inng tissne dietl within 4 days. There 
was no swelling or reddening of the ear. Lungs deeply congested (hypostatic f). 
numbers of awiuo-plague bacteria in blood, spleen, and liver. Ga.U!u«»> 



£ 



J 





26 ' 

aaS liver uontaineil tbe same orgauisma. A monea inocnlated 
bit of Innj; tieaiio anccumbed witbin 2 daya. BoiCteria very scarce in body. Pore 
cnttaiea of a wine-plague bacteria were, honever, obtained froru heart's blood. 

What is of importance in this case anil in No. 4U2 is the absence of 
bog-cUolera biicilli from the internal organs where we wonld certainly 
expect to liml them in this disease. If we refuse to consider the intes- 
tinal lesions as caused by swine-plasne bacteria, we have the alter- 
native of assuming the existence of bacteria which produce intestinal 
disease without penetrating into the internal organs proper.* 

Five other cases in this investigation deserve special attention. Sob. 
408, 409, and 4t0 of the same herd still remained on the farm. After 
the examination of 407 had shown the absence of hog cholera, and the 
presence in the diseased longs of swine- pi ague germs, and the evidence 
thus far obtained pointed to a different disease caused by the latter 
bacteria, two pigs, Nos, 359 and 360, were taken from the Station to the 
farm and penned with the three mentioned to determine whether the 
disease is readily coromunieabte. This was done February 28. March 
5, No. 408 died. March Ifl the remaining four were taken back to the 
iStation and pl^cetl in an naused pen free from infection, so as to be 
nnder observation. 

Of these four pigs No. 409 died March 20, No. 410, March 29. Of the 
exposed animals No. 359 died March 24, 24 daj's after the comuence- 
ment of the exposure ; No. 360, April 6, 37 days thereafter. Of these 
fonr cases No. 360 was not examined. Of the remaining three, hog- 
cholera bacilli were detected in 400 by rabbit inoculation, but not in 
either 408 or 410, while swinc-plagne bacteria were found in 408 and 
359. Looking over the original notes I am convinced that the number 
of cultures made from the spleens of 403, 410, and 369 were sufficient to 
enable ns to exclnde the presence of hog cholera from these cases. So. 
409 is therefore the only animal from the adjoining farm which was ex- 
amined in which hog-cholera bacilli were detected. It is likewise 
strange that in the spleen of No. 40S a bacillus should appear resem- 
bling hog-cholera bacillus in many respects, but not identicivl with it, 
and producing only suppuration in rabbits. 

The cases which came under observation subsequently, and in which 
hog-cholera bacilli were readily demonstrated in the spleen, were Station 
pigs which had been exposed some time ago to the infection of hog 
cholera. These cases are chiefly valuable in pointing ont that the swine- 
plague bacteria are transmitted from animal to animal and associated 
with Inng disease. They may be thrown out altogether, since the 
source of the hog-cholera bacilli is traceable. 

So. 372. Fed viscera of hog cholera case December 24, 1886, in infected 



* IJy " internal organs" I iniian those orgnna whicli do not oome in oontnct with the 
&ir or food, eitber diieuily ur IrsdiructI;. Thns tbe eatire reapirntoTy and digeatlve 
tract may be regarded as external, so far aa bacteria are conocraed. 




27 

H"o. 378. Fed viscera of hog cliolera case November 18, 1886, in in- 
fected )ien. Fed viscera of i06 February 3, in infected pen. 

No. 393. luocnlated with swine plague bacteria (Iowa) January 25; 
placed in the infected pen March 28, 

No. 397, Fed viscera of 378 in pen 7 March 34. 

In 372, 392, 397, both hog cholera and swine plague bacteria were 
fonnd. Their presence in the old infected pen or their contact with 
pigs kept there will account for this donble infection. 

The facts brought out by this investigation corroborated those al- 
ready brought out in the investigations of the preceding year. They 
showed the existence of pneumonia and pleuritis, together with intesti- 
nal disease in most of the animals examined, ^sociated with bacteria 
readily distinguished iirom hog-choleni bacteria. 

They also demonstrated the transraissibility of the pneumonia to other 
pigs, and in these pigs the same bacteria were found. 

If the lesions of the large intestine, as observed in the early cases, 
were due to hog-cholera bacilli, why were these bacilli not found ex- 
cepting in one late case in which there may have been an accidental 
infection of the rabbit inoculated i Why were hog-cholera bacilli read- 
ily detected in the later cases kept in the infected pen ? 

While these investigations do not prove that the swine-plague bac- 
teria were the cause of the intestinal lesions, they also do not seem to 
show any relationship between these lesions and hog-cliolera bacilli. 
This question of the relation between intestinal lesions and swine- 
vplagne bacteria will be {liscussed farther on.* 



In September, 1888, an outbreak of swine disease near Baltimore, 
Md., came to our notice. Three pigs from one herd and one from another 
herd were examined. The following synopsis of the cases may be of 
interest, the full account being given elsewhere.t 

Pig No. 1. Bronchopneumonia; exudate on mucosa of rectum and 
lower colon ; swine-plague bacteria detected in lungs and rectum ; hog- 
cholera bacilli in sijleen. , 

Pig No. 2; Three-qnarters of both lungs hepatized; ulcers in ileum 
and colon ; swine- plague bacteria in lungs ; bog-cholera bacteria in 
spleen. 

Pig No. 3: Extensive pneumonia and pleurisy; ulceration of large 
intestine; swine-plague bacteria in lungs; hog cholera bacteria in spleen. 

Pig No. i: Slight atelectasis of lungs; ulcers in large intestine; 
swine-plague bacteria in large intestine; hog-cholera bacteria in spleen. 

Pig No. 3 was taken to the Experiment Station, where it became the 
starting point of a mixed outbreak of hog cholera and pneumonia. 

' P. loa. 

i Bepoit of the Bureau, etc., lUtlT-'S6, p. 121. 



J 



I 

I 



During November, 1883, the writer waa directed to make some in- 
vestigations iQ Iowa,* where swine diseases at that time were prevail- 
ing to a considerable exteot. lu the vicinity of Masuu City pigs from 
three herds, some distance apart, were examined. The leaioiis obaerred 
were both intestinal and pulmonary. The intestinal lesions, though 
varying considerably in appearance and intensity, did not differ, on the 
whole, from those observed in hog cholera. The lung lesions varied 
considerably in character and extent, from a slight coDapae in a single 
lobe to almost total hepatization, accompanied by exudative plearitis. 

The investigations were limited to postmortem examination and 
caltures from the spleen. From each spleen small bits of tissae were 
removed to two tubes of agar. In addition, portions of diseased lung 
tissue and ulcerat«d mucous membrane from the large intestine were cut 
ont and transferred to sterile test tubes plugged with cotton wool for 
inoculation into rabbits. Ten pigs were examined in this manner. 

In but one case did the spleen pulp show any bacteria under the 
microscope, and in this case they were streptococci, [n but one agar 
tube of the spleen series did anything develop. This was a motile 
bacillus, resembling the hog cholera bacillus in form, but differing in 
its growth on agar, in bouillon, and in gelatine, this growth being in 
all cases more vigorous. Of two mice and one rabbit inoculated, one 
mouse died in 5 days. The lesions were indefinite and did not point 
to hog cholera. Moreover, the other mouse and the rabbit remained 
unaffected. 

With particles of diseased lung tissue and mucous membrane from 
some of these cases a considorable number of rabbits and some mice 
were inoculated. Of those that died some contained no bacteria of any 
description. Those inoculated from three cases out of ten died of 
swine plague since these bacteria were found. A few survived the 
inoculation. 

The nature of this disease was not, therefore, cleared up by these in- 
vestigations, since the results were not uniform. While in hog chol- 
era the bacilli are present in the spleen, and readily obtained therefrom 
by cultivation, they were not present in the spleens of these ton cases. 
As already stated, swine-plague bacteria were obtained from three cases. 
They were quite virulent, as the inoculalions upon pigs show. Thus 
one pig, which received 9 cubic centimetres of a bouillon cultoie into 
the right lung through the chest wall, died within 20 hours of septi- 
cemia, the injected bactoria being present in the spleen in considerable 
numbers. Another pig, which received a subcutaneous injection atthe 
same time, remained well. Somewhat later two pigs received into the 
right lung IJ cubic centimetres and 3 cubic centimetres of a bouillon 

* Report of the Bureau of Aniiual Iiidiiatry for lBST-'g6, pp. ISO-Hii, nLere a de- 
int of this work is given. 



29 

calture. The one which had received the smaller dose was sick for a 
time, but recovered. It was killed 1 J months after the inocuIatioD, and 
both Inngs were foaiid everywhere adherent to the chest wall. In the 
pericardial sac a considerable quantity of pus had collected, in which 
the iujected bacteria were stiU present, as determined by cultares. 

The animal which had received the larger dose became very ill and 
was killed 5 days after inoculation. At the autopsy were detected par- 
tial hepatization of the right lung, with extensive exudative pleuritis 
and pericarditis. 

The two following cases, which have not yet been published, demon- 
strate very strikingly the virulence of these bacteria. The growth on 
a number of agar cultures about 9 dayg old was scraped off and trans- 
ferred to sterile bouillon until a turbid auspeosiou was obtained. This 
suspension was prepared because these bacteria multiply very feebly 
in bouillon, and when the latter ia nsed as the injecting fluid very few 
bacteria are actually introduced into the body. This turbid suspension 
was used to inoculate 2 pigs. No, 120 received into the abdomen 2 
cubic centimetres; No. 143 into the right lung through the chest wall 
but 1 cubic centimetre. The inoculation was made March 11, 1889, 
over 3 months after the bacteria had been obtained from the diseased 
swine. 

No. ISO, Eaaex female, 5 luontha old. Into the riglit luug tliTOugli tbu cbeat wall, 
2 caLio centtmetrea of above aiiapeuaion InjeotBd with hypodermic ajringe, C p. m. 
March 11. ^ound dead early next Dioming. 

SabcutaDeons iogaiual glands patti; hemorrhagic. Frum the cnt eDbcntaneoiis 
vesse!a of right aide liqnid blood oozea ont. Id abdomen the solitary folliclea of 
iaige intestine appear a,^ bright led circular spots tbree-aixteentha inch diameter, as 
seen from aeroaa. Spleen aligbtly engorged. 

Loigo quantity of blood-atained aeram in right pleural sao. The needle had punc- 
tnred the convex surface of principal lobe, where there wasBonie iofiltratioD of blood. 
A tbiu layer of fibrin on convex surface of the amall anterior lohea and on pericardium. 
A few collapsed lobules along free border of these lobes. 

In atomacb, the macosa of fnudna is deeply reddened over an area of 3 to 4 square 
inahea; in thia area two hemorrhagic spota. The upper half of dnodenum with 
mucosa intensely reddeued. Contents somewhat blood-ataiued. All Peyer'a patobea 
in the amall inteatine Itoin dnodennm to ileo-oiecal valve are intensely reddened, 
the folliclea appearing as blood-red points. On some patches, hemorrhagett on the 
surface. Couaidurable number of asoarldea in amail intestine. In large inteatine 
the lymphatic patch near valve likewlae reddened. Mesenteric and meaooolio glanda 
hyperivmic. 

Kidneys very much congested. The glomeruli appear as minute hlood-rad points. 
Small quantity of urine in bladder loaded with albumen. Blood fails to clot. In 
the spleen large numbers of swine plagno bacteria. 

No, 143. Essex male, 5 months old. Injected into abdomen 1 cabio centimetre of 
turbid suapenaion of awine plague bacteria, March 18. Animal diea 40 hours after 
inoculation. 

Inguinal glanda slightly swollen and hyperiumic. In abdominal cavity peritoneum 
pale pink, all minute vessels injected. Bhrcds of a viscid grayish exudate attached 
to abdomiDal walls, oontignous colls of intestines, s.nd stomach. ConsideTabli.' opaque 
reddish acrum present. Veaaela of diaphragm injected; aome eochymosea observed. 
The shreddy exndate aleo present. The mesenterj tBABtaatoaa, B6^<isiv^-i 's^«i^s> 



30 

attached to intestines. The walls of a portion of the lower small intestine very 
much swollen, serosa dark red. On the mucosa which is congested a yellowish, 
pasty exndate loosely rests, occupying the side to which mesentery is attached. 
This exudate is made up of leucocytes imbedded in strands of fibrin. Peyer's patches 
along this region and down to ileo-csecal valve are deeply congested and swollen so 
as to appear boat-shaped. (The bacteria had evidently traveled along mesentery 
and invaded the walls of the small intestine. ) 

Large intestine distended with dry feces. Mucosa of caecum and colon more or 
less congested, the congestion limited mainly to summits of folds. The lymphatic 
patch near valve very hypersemic and swollen. 

In each pleural sac about 50 cubic centimetres of reddish serum. A thin* membra- 
nous exudate covering the dependent half of both lungs easily scraped away as a 
pale yellowish pulpy mass. The remainder of pleura opaque, a barely visible exu- 
date covering it. The lungs are hypersBmic, the free border of the ventral and ce- 
phalic lobps collapsed. Bronchial glands swollen and hypersemic. 

Pericardium thickened, clouded ; vessels injected. A barely visible exudate on it. 
Vessels of heart surface very much distended. Petechia) on left auricle and under 
endocardium of left ventricle near semi-lunar valves. Bight heart distended with a 
dark, soft coagulnm. 

In the peritoneal exndate, which consists chiefly of fibrin and a few leucocytesi 
immense numbers of the injected bacteria are present, showing after staining the 
polar arrangement of protoplasm very distinctly. The pleural exudate composed of 
the same elements. In some leucocytes up to twenty bacteria. In the spleen and 
blood from the heart large numbers of swino-plague bacteria. Agar cultures from 
the spleen, pleural, and peritoneal cavities contain only the injected bacteria. A 
bouillon culture from the spleen likewise pure. 



ISVKSTISATMS OF l889-'90. 



The problem of swine diseases as it stood after tlie completion of 
these iuvestigatioiis up to IS89 may be stated briefly as follows: 

Since 1885 a well-characterized bacillus has been eacouDtered as the 
cause of au infectious disease termed hog cholera, which is chiefly 
localized in the large iutustiue. Siuce 1S86 our attention has been 
directed to Inng disease in swine with which a bacterium is associated, 
which, when inoculated into awine, proves to be very virulent and may give 
rise to pneumonia when the bacteria are injected into the lungs. This 
is sutiicieiit to demonstrate the esisteuce of a disease differing from hog 
cholera, which has been called swine plague because an identical dis- 
ease of swine in Germany, first described in 1885, was called Sehweine- 
aeuclw. This lung disease was showu to be communicable. (IV.) • 

In many of the outbreaks examined the changes found in the intes- 
tines could not be distinguished from hog cholera (except perhaps in 
IV). In some hog-cholera bacilli were actually detected, in others 
(I, VI) they could not be found. One of the problems, therefore, still 
before us, and a very important one, was to determine whether all out- 
breaks of swine plague in which intestinal lesions closely resembling 
those of hog cholera are present are mixed outbreaks of swine plngue 
and hog cholera, or are simply swine plague. 

Much light has been thrown upon this subject by the investigations of 
three outbreaks given in detail in the following pages. The first is a 
mixed outbreak in which, however, the lung lesions are so very well 
marked and the swine-plague bacteria associated with these lesions so 
virulent that there can be little doubt that the hog cholera disease was 
really secondary to the swine plague. The seeoud outbreak is simple, 
uncomplicated swine plague. In the third outbreak very virulent swine- 
plague bacteria, and, iu oue case, very attenuated hog-cholera bacilli 

fwere found. 
^ VII. 

An outbreak of swine disease appeared among the pigs belonging to 
an abattoir adjoining the Experiment Station about the first week in 
October, 1889. The disease came to our notice a week after the first 

' Tlieee namerala refer to the different (mt\)realVi.a aH\ivvm\iBi;tA vti^^iAft^'i'*''^- 



I 



ss 

animals died, and in attempting to trace tfae oansea whiob led to it ve 
obtaioed the following information : 

Tiie pitjs were piircbased iu the marketa of Washington City the lat- 
ter part of September. They were thirty-five in nauiber, in two, possi- 
bly three, lots. One lot came in two crates. It could not be deter- 
mined whether it was made up of pigs from one or two sources. They 
1 to die, as stated, about a week after their arrival. We examined 
iu all thirteen animals, the first on Octolker 12, the last on Uctober 28. 
A few days later the last of these thirty-live pigs snccumbed to the dis- 
ease. It lasted, therefore, about 1 mouth. A few large swine which 
were on the place when these animals arrived did not take the infection. 

In the following pages a detailed statement of the pathological and 
the baeteiio logical examination is given. Those who are not specially 
interested in these notes will find a summary of the ascertained facts 
following them. 

No. 1. October 12. Male pig, weighing about ^ pounds, died last night. On inner 
aapect of right thigh an aroa, nboat one-hatf inch in diaiueleT.of estravafiation, ex- 
tending down into tme skin. Nu nlcera in the mouth. Spleen not enlarged. 

CoDtentB of stomach nltght in amoDDt, coDsisting cbitflj- of asod and a tnrbid 
liquid; walla contraoled, throwiug maoosa into large folds. Tho greater part of 
mncoea intensely coDgested. In the fondas a large ulcer 1} incheH across, coreted by 
a slough one-quarter inch thick. The subjaeenl w»ll nearly oue-half inch thick, on 
section deeply reddened througboat, due to a sanguinolent, owleinatonB inRltratinu 
of the wajl. Adjacent to this a sraaUer indanimatory thickening covered with a thin 
pultaoeons slough. The mucosa of duodennm uniformly and deeply pigmented. Id 
the ileam the ninuosa is swollen, Peyer's patches reddened. 

Mucona of CLecum of a hluish-gray color, dotted with a small nnmber of aloers not 
much larger than pins' heads, ouTered with yellowish sloughs. Sinnlar foUicnlar 
ulcere on Peyer's patch near valve. Upper colon contains roach earth, adhering rather 
closely to mucosa. The latter quite deeply pigmented, the pigmentation intensified 
in lower colon. In npper colon a email nnmlrar of flattish yellowish* white slonghs 
fh>in one-sixteenth to one-eighth inch in diameter. 

In thorax, the plenra covering the diaphragm and ribs is overlaid by a pate 
pinkish membranous exudate, easily rubbed off and especially abundant on the right 

The various lolioa of hoth Inugs firmly glued together by exudate. The vetitral 
lobea, the major portion of cephalic lobes, and a small portion of the principal lobes 
adjacent to the ventrals are bepatized. The hepatized areas are covered by false 
membranes varying in thickness and easily peeled off. Through the hepatized lobes 
are diHsuminated necrotic masses of a greenish color varying in si^e from mere specks 
to peas. Tliey contain large numbers of swiue-plague bacteria, which show a polar 
Btaiu very dearly. The tissue around the terminal portion of both hrouohi in the 
principal lobes is hepatized and contains necrotic foci. Lung wurnis abundant in 
the left bronchos. Both bronchi contain small quantities of reddish foam. Peri- 
cardium tbiokened, opaque j vessels injected; the ventral surface is covered by a 
merobr;inous exudate and it is adherent to the heart surface by means of a similar 
exudate. Cover-glass preparations from tbe pleural and pericardial exudate, from 
various regions of hepatized lung tissue, contain large numbers of swine-plogne bao- 



A rabbit was inoculated October 12, by placing 
of abdomen. Dead nest raorniug. Slight eechy 
of inoculation. The blood and spleen contain i 



of lung tissue under the skin 

I in the snbcutis at the point 

numbers of a 




33 

bkoterla, sliowing well thepolararcangenieut of the protoplasm whan staiaed. Cnl- 

tnres coufirinatory, agar anil bouillon being nHBd chieay. 

A rabliit [noanlated at tlie autne time and ia (lie same way with a bit of apleeu 
tisane. Kabbit dead next morning. Swine plague bacteria fewer tbau in preceding 
case. An agar oulture from the blood contaios only these germs. From the spleeu two 
agar, oue bouillon, and one gelatine tube culture prepared. On the seoondday (Sun- 
day intervening) a moderate nnniber of isolated eoloniua «u the agac surfucua; the 
condensattou water turbid witb flaky deposita. In the botiilluu tube are a large 
iiumber of minute suspended flakes, the liquid itself not clouded. In these coltuiea 
only swine-plagoe bacturiu. The gelatine tube remained slerile. 

From the pleural esutlate an agar and a bouillon tube wore inoculated at the 
autopsy. Ou the second day a number of colonies similar to those on the spleen agar 
onltnre were found to be made up of swine-plague bacteria. The bouillon oulture 
(aintlyand uniformly clouded. Only swine-plague germs present. From theepicar- 
dial eiudute two similar cultures wore i)Cepared with the same result, with the ex- 
ception that in the bouillon culture large uocci were also present. 

With a bit of lung tissue taken from more recently disoasi^ regions two gelatine 
rolls and two agar (ilates were made. In the Becond gelatine roll about 100 minute 
oolonies present after 3 or 4 days. These were examined and bouillon tubes inocu^ 
lated from four dilfereut oolonies at different times. lu all the swiuu-plagne germa 
only appeared. The first agar plate developed a very large number of oolonies, the 
seoondonly six or seven, made up only of Hwine-plagne germs. 

No. 3. Female; died last night ; weighs about 35 pounds. Lymphatics iu the groin 
barely enlarged, pale, Spleeu quite large, softened, dark red in color. 

Digestive tract : Stomach partly fillud with chewed leaves, and straw adhering 
slightly to mucosa. Fundus faintly reddened. The pyloric portion bile-stained. 
Duodenum similarly stained. An ascaris in the bile duct, projecting 1} inches out 
into duodenum. Arboruseeut jujeotiou of mucosa of the latter. Considerable quan- 
tity of tnrbid liquid in large bowels. Mucosa not pigmented. Foyer's patch at base 
of valve thickened and pigmented. Llloers moderately abuudunt in c»anm and 
upper colon. They appear as little cup-shaped depressious, o no-si xiteenth to one- 
eighth iucliiu diameter,lin6d with a pale yellowish necroticlayer, the center in some 
filled with a black slough and the margin elevated. Mesenteric, mesooolic glands, 
and those of lesser omentum, slightly swollen ; cortical layer congested. Interlobu- 
lar warkiugs of liver promineui, broadened. The section appears mottled, some lob- 
ules being much more congested than others. The empty gall-bladder contains a 
partly disintegrated ascaris, which extends through bile duet into duodenum. 

Thorax: The costal pleura of both sides highly injected and covered with a thin, 
whitish membranous exudate, gluing the lungs to the chest wall. Of the lungs all 
but ft small strip along the dorsal border of the principal lobes is solid, three or four 
times the size of the normal luug when collapsed. The various lobes are glued to 
each other, forming a single mass, in which the individual lobes are not lecoguhnble, 
and which is in turn attached to the chest wall, the diaphragm, and the pericardium 
by plenritio exudate. This is most abundant, and forms membranes on the most de- 
f>endeDt portions of the lungs, easily pulled away from the subjacent structures. The 
•various adhesions torn withcuit dilBculty. 

The disease seems farthest advanced i[i the cephalic and ventral lobes, in which 
are imbedded a large number of closely set masses of dead tissue, from one-sixteenth 
to one-half 1 noh in diameter. Th b y II w h masses, sharply defined in 

outline, and imbedded iu dark dhptzedt lihia mottled with paler 

specks, representing the ultimate Ibl dt ddwth 11 masses. 

The trachea and bronchi cont wh t h f mm ed with large quantities of 
thiek, purulent secretion. In th b h f th p ipal lobes ii 
monoB. The bronchial glands a hyp aim a d ojd u tons, and cputain a. small 
ffSflibprofr 

1614- 



84 

In the spleen a few minate oval bacteria detected. With a platinum needle the 
Bnrface of an agar tnbe and a bonillon tube inoculated. On following day the 
former showed a considerable number of round, grayish colonios, 1^ to 3 millimetres 
(one-sixteenth to one-eighth inch) in diameter ; condensation water clouded. In this 
tube only swine-plague germs detected. The bouillon culture contains a considerable 
number of minute granules, representing clumps of swine-plague bacteria. 

An agar culture from the liver grew like the spleen culture and contained only swine- 
plague germs. 

At the autopsy an agar and a bouillon tube inoculated from the right pleura. In 
the former only the condensation water became turbid and contains swine-plagae 
germs exclusively. The bouillon tube remains sterile ; similarly a bouillon tube from 
pericardial exudate remains sterile. (It is highly probable that the flocculent growth 
of the swine-plague germs in bouillon and the sterility of these tubes was occasioned 
by an unsuitable condition of the bonillon.) 

From a bit of lung tissue, the pleural surface of which had been thoroughly 
scorched, gelatine roll cultures were prepared. After a number of days the first roll 
showed a large numbei of colonies as mere points, the second roll about 100 colonies, 
somewhat larger. From both tubes bouillon was inoculated from individual colonies. 
These contained after development only swine-plague bactena. 

At the same time the scorched lung tissue was pricked with platinum needle and 
an agar tube inoculated. On the surface a considerable number of similar colonies 
appeared on the following day. Some of these examined were swine-plague germs. 
In the condensation water a few chains of a short, motionless rod appeared among 
the great bulk of swine-plague germs. 

At the same time a rabbit was inoculated from the lung tissue. It was dead next 
morning. Enormous numbers of polar stained swine-plague germs found in stained 
preparation of spleen pulp. An agar culture confirms the microscopic examination. 

No. 3. Died last night. Female ; weighs about 25 pounds ; in very poor condition. 
Spleen considerably engorged ; contains a small number of bacteria ; nature to be 
determined by cultivation. 

Digestive tract : One ulcer on the gums of lower jaw. Stomach contents like 
those of No. 2. In the fundus an area of mucosa, about 4 inches in diameter, is nearly 
black from extravasation, and thickened. A zone several inches wide outside of this 
is deeply reddened. The mucosa of duodenum and ileum more or less discolored the 
vessels, showing arborescent injection. In the csBcum, the mucosa is of a bluish- 
gray color, and dotted with a dozen sloughs, one-eighth inch diameter, of a yellow 
color ; the tissue at the margin of the slough thickened, elevated. The Peyer's patch 
near valve deeply congested and sprinkled with enlarged grayish follicles. Mucosa 
of colon more or less discolored and hypersemic in patches; only three small ulcers 
found. The liver appears normal, the bile in bladder very thick, flaky. Punotiform 
ecchymoses on surface of kidneys. 

In the lungs the major portion of both ventral lobes is solidified, the tips being 
emphysematous. The hepatized portions are bright red in color, with faint yellow- 
ish mottling. 

Bacteriological examination : Cover-glass preparations of the hepatized lung tissue 
show no bacteria. From a bit of tissue two gelatine roll cultures prepared and a^ 
rabbit inoculated. Roll A subsequently contained a large number of apparently iden- 
tical colonies. Roll B, about fifty of the same colonies and one chromogene. Care- 
ful examination of these revealed hog-cholera bacilli. The inoculated rabbit died 
within 36 hours. At the place of inoculation the bit of lung tissue was surrounded 
by a small area of purulent infiltration and dilated blood-vessels. In the blood and 
spleen a very large number of swine-plague bacteria. A bouillon culture from the 
blood faintly clouded on the following day, and holding in suspension barely visible 
granules made up of clumps of swine-plague bacteria. No motile bacteria detected. 

The sp leeu pf the pig contai4ed ^ few b£|.ct)eria; character not determinable^ Witb t^ 



I: 

E 



^BrtTj 



35 

bit of pulp a gelatine roll A and agar plate B pieparuil, iilso n liotilllon ciiUiire. The 
latter wag uniformly oloiided ou tUe followiug ilaj ; a few giis biibliles on tUoantfaoe. 
Only motile Iiog-cho!ara bacteria present. Tbe presence of hog-cholera bacilli in tlio 
Bpleen was furthermore demonstrated by the roll and plate culture. The agar plate 
grew, of oourae, most rapidly, being in tba thermostat. On the second day a consid- 
erable number of culoniea appearud, apparently the same. Eiaraination of aome 
abowed only bog-cholera bacilli. A. honillon tnhe inoculated from one of thorn was 
clouded on the following day with motile hog-cholera bacilli. 

One-fifth ouhic centimetre of the origiual bouillon culture was injected subouta- 
neoualyinto a rabbit. On the fourth day temperature 1(H1.I° F. Found dead on the 
seveuth day with tbe usual lesions of hog cholera, snch as engorgeil Hpleon, ueorotio 
pDoi in the livor, reddened Payer's patches, hemorrhagic poiiita on the lower colon 
and reclani. Spleon and liver contain hog- cholera bacilli in moderate numbers. 
From spleen an agar and a bouillon culture prepared by piercing spleen with a fine 
platinum needle aud inoculating culture meilia therewith. In buth ouly hog-cholcra 
bacilli appeared. The original spleen culture contained no swiue-plague germs, 
otherwise tbe rabbit would have saccnuibed withiu 1 or S days. 

In the gelatine roll appeared after a few days a very large nuujber of the same 
'oolonlee, evidently all hog cholera- 
No. 4. October 14, Small male pig, weighing about 30 pounds ; died last night. 
Skin of abdomen slightlv reddened. Siiboutaneoas ingninal glands enlarged, 
lematouB, mottled red and pale. 
Mouth free from ulcers. Contents of stomach stained with bile. Mucosa of fundns 
over an area 4 inches square deeply congested, swollen. Slight iiijectiou of minute 
Tosseh in duodenum; remainder of small intestine normal. Large intestine con- 
tains a turbid liquid and a substance resembling cnal ashes. The mucosa of ciecnm 
studded with supevflciul, yellowish sloughs, abont the size of pins' Leads or a little 
larger. In the colon, besides these small yellowish sloughs there are three or four 
large areas over which the mucous membrane is entirely necrosed superficially. 
These areas are nbont G inches long. The minute sloiighs limited chiefly to the 
upper half of tbe colon. 

Liver rather firm in t«xture, the acini projecting slightly above interlobular tiiMue 
ou the surface. Glands near the portal fissure deeply congested throughout. 
L Dilatation of pelvis of kidneys eaocoaohiugou medullary portion to a large extent. 
Both ureters very much distended ; walls from one-half to tht«e- quarters inch thick. 
JFliUngs collapse when removed from thorax; no pleurltis. In all the lobes there 
tat masses of collapsed and hepatized tissue varying in diameter from one-half to 
several iuchea. They are situated chiefiy near tbe roota of the lobes. Tbe small 
median lobe in [lart liopatized, bright red with yeliowiah mottliug. In tbe terminal 
bronchi are plugs of lung worms imbedded in thicli moco-pus. The tissue around 
tbe plugs in the left principal lobe hepatized. 

Bauteriulogical eiamiuntion: With bits of diseased lung tissue two gelatine rolls 
were prepared and a rabbit inoculated. The rolls both contained on the second day 
number of colonies of micrococci, evidently a contamiuntion of the gela- 
The inoculated rabbit died in 4 days with enlarged spleen and patches of 
the liver in tbe form of a net work. An agar culture from the spleen aud 
a bouillon culture from heart's blood botb anbsequeutly contained only bog-cholera 
bacilli. No swiue-plague germs detected, although the rather premature deoth of 
the rabbit led mo to suspect their presence. Some weeks later a rabbit was inocu- 
lated subcutaneously in the ear with a platinum loop of the blood culture of the 
preceding rabbit. This rabbit died in 5 days with hog-cholera lesions. 

With a bit o( spleen pulp of tho pig a gelatine roll A and an agar plate B were 
prepared ; also a bouillon tube inoculated with platinum ncedio after pricking tbe 
spleen. This developed into a pure culture of hog-cholera bacilli. In tbe gelatine 
roll appeared nnmero us colonies of hog- cholera bacilli. The agar i>late was partia.U.1 
~ "grown I the few isolated colonies were made ug of liog-ti\iii\iiYa.\iwiSi\. 



i 



36 

From the liver a gelatine roll, an agar and a bouillon tabe inoculated, each ^th 
minute particles of tissue. In the roll numerous colonies appeared, evidently all hog 
cholera. The two tube cultures likewise contained only hog-cholera bacilli. 
No. 5. October 15. Small male pig, weighing about 25 pounds, died last night. 
Skin about nrinary meatus reddened. Subcutaneous inguinal glands enlarged, 
firm, juicy, faintly mottled with red. 

Stomach contracted. Contents same as in preceding oases. Mucosa in large folds, 
summits of which somewhat reddened. Slight discoloration of mucosa of lower ilenm. 
Contents of large intestine firm, in form of lumps. In the caecum about ten ulcers 
from one-eighth to one-half inch in diameter, the largest button-shapped, flattisb a 
firm, yellowish, necrotic base extending into subjacent muscular coat. Complete 
necrosis of Foyer's patch at valve. In the colon a small number of large and small 
button ulcers. The solitary follicles projecting as large as split peas. When squeezed 
a white soft mass exudes from a central depression. 
Liver rather firm in texture. Gall bladder contains semi-liquid, flaky bile. 
Spleen slightly enlarged. Kidneys on section very pale. 

Both lungs oDdematous. Hepatization involves the free tip of both small cephalic 
lobes of the right lung, the major portion of the ventral lobe of the left lung. In 
both principal lobes are a moderate number of small hepatized foci. In both bronchi 
a large quantity of very viscid muco pus, which extends down into the branches of 
the principal lobes. These latter and the terminal portion of the principal bronchi 
contain plugs of lung wovms. Bronchial glands enlarged, firm, pale. 

Bacteriological examination : In cover-glass preparations from the spleen a very few 
bacteria resembling somewhat hog-cholera bacilli seen. An agar culture inoculated 
with platinum wire remained sterile. On the following day spleen taken from re- 
frigerator and a second agar tube inoculated with particle of pulp. In this tube a 
colony of greenish fluorescent bacilli appeared. 

From hepatized lung tissue two gelatine rolls were prepared. The first one was 
spoiled by a few liquefying colonies; the remaining small colonies were inaccessible. 
The second roll remained sterile. 

A rabbit inoculated snbcutaneously with a particle of lung tissue died in 24 hours. 
At the place of inoculation considerable purulent thickening of skin with ecchymosis 
of the subcutis. Numerous very small coccidia cysts in liver. Spleen enlarged, 
congested. (Bacteriological notes of this rabbit mislaid.) 

No. 6. October 15. Small female in very poor condition ; died last night ; more or 
less decomposition. Ventral aspect of body reddened. Subcutaneous inguinal glands 
enlarged, firm, and very hypersemic. 

Stomach much contracted, empty. Mucosa of fundus beset with pnnctiform hem- 
orrhages. Small intestine not marked by changes ; one ulcer in lower ileum. Con- 
tents of caecum and colon of a somewhat pasty consistency mixed with coarse sand. 
In the caecum about six old, flattish ulcers, from one-fourth to one-half inch in diam- 
eter, also a patch of easily removable, membranous exudate several inches square- 
In the colon near the valve several ulcers and a similar patch of exudate. 

In the lungs the hepatization, though extensive, is more or less scattered in foci as 
follows : 

A few hepatized foci in left cephalic, one large hepatized mass in ventral, and four 
wedge-shaped masses in left principal lobe. In the right lung, fully two-thirds of the 
median and the whole of the ventral lobe solidified. The latter lightly glued to the 
neighboring lobes. Disseminated through it are very many necrotic foci about one- 
eighth inch in diameter. In the right principal lobe several hepatized masses. In 
both bronchi a large number of adult lung worms. Pericardium thickened ; vessels 
injected. Spleen not enlarged or congested. 

Bacteriological examination : Spleen found more or less decomposed. No germs in 
cover-glass preparation. In an agjar culture therefrom numerous isolated and conflu- 
ent hog cholera colonies appeared on following day. 
A rabbit inoculated suboutaneonsly with a bit of lung tissue (the particular xegion 



37 

not indieatBd In the notes) wan fonud dnail on the eiglith Aay. EKt«ndtng from tb« 
point of iitucolatjou over the oatire alnlomtm atid portion of thorax the aubcntis is 
inliltrated with a yellowiab, paaty mass of pu9, Htain^d with lilood. The aoperiicial 
layer of inuBcleB discolored, ccehyjaotic. Spleen slightly enlarged. No peritonitis. 
CultuteBfrom the spleen remained sterile. An agar plate from the snbcu tan eons exu- 
date spoiled hy condenaatioa water. An agar ttibe from the same sonrce remained 

No. 7. October 15. Small male pig, of abont 35 ponnds, died yesterday afternoon 
late and put in refrigerator until neit morning. Animal in fairly good condition. 
The lesions in this ease were briefly as follows : 

Digestive tract : Fnndns of stomach faintly ri?dduiied. Small intestine not affected. 
Contents of large intestine liquid, of blacb color, holding much earth in suspension. 
One ulc«r on the thickened Feyer's patch near the valvo. FollJoIeN swollen. No other 
changes. 

Lnngs: General pienritis indicated on the most dependent portions. of the left long 
by a thill, membranous exudate, elsewhere hs roujjhening. The varioQS lobes lightly 
glned together. Hepatization limited to the tip of the left ventral and a small area 
in the left principal lobe, containing numerous uecrotic foci. In the right principal 
lobe two wedge-shaped, hepatized masses, in which are many minute oral germs, ra- 
sembling swine plaguo, Genernlized bronchitis indicated by much curdy (nnco-pus 
in the bronchi and branches. No lung worms detected. 

In the liver, the center of many lobules in all the lobes of a brick-red color, caused 
by fatty degeneration of this portion of the lobule. Bile very thick, dark-colored. 

Spleen very much enlarged, softened, dark colored. 

Bacteriological examination: From this animal only the spleen and the pleural 
exudate received any attention. An agar tube inocnlated from the spleen simply 
with a platinum wire was sterile on the following day, althnngh bacteria had been 
detected in the spleen pnip in cover-glass preparations. A second tube inoculated 
with a particle of pulp from tho spleen, kept n.eanwhile in the refrigerator, developed 
a large nnmber of isolated and confluent colonies. So far as eoiild be determined 
these were all swine-plague bacteria. No motile bacteria present. 

An agar culture made at the autopsy from the pleural exudate proved to be a pnra 
aolture of swine-plague bacteria. 

No. 8. October 17. Male pig, weighing abbut 35 pounds, died last night. Snb- 
cntaneons inguinal glands enlarged, on seotinn dotted with minute petechiie. 

Stomach normal. Dnodennm bile-stained. In lower ileum much liquid, containing 
line earth and sand. Inciecnm minute vessels of mucosa Injected. Feyer's patch at 
valve somewhat swollen and discolored. In the upper colon several small patches of 
thin exudate, about one-foarth inch in diameter ; the subjacent epithelium appeared 
necrosed. In both kidneys infarcts of a, yellowish, homogon en us appearance, sur- 
rounded by a hyperiemic zone, and visible from the surface of kidney, two in the left 
and twelve iu the right. 

Spleen somewhat enlarged, firm. Liver very pale, pulp rather soft. On the left 
lobe several paler spots, not elevated, about oue-fimrtb inch in diameter. Bile thick, 
flaky. 

Lnngs everywhere adherent to surrounding strnctures by means of a nieinhrauous 
exudate, grayish, elastic, coming away In patches and shreds when pnlled. Tbis 
membrane especially thick between lungs and diaphragm. The various lobes matted 
together and adherent to perioardium. Lungs do not collapiie. 

Loft ventral and cephalic lobes completely hepatiiied. Throughout both are dis- 
seminated a large number of greenish- white, homogeneous, Arm masses from one- 
fourth to one-half inch in diameter. Almost entire right lung faepatized. In the 
cephalic lobe, ventral lobe, and cephalic portion of principal lobe the necrotic massea 
aT« very nnuierous, one near tip of ventral lobe qnite large. The hepatization of 
thepriiioipal lobe is of the dark-red variety. 



J 



88 

Large qaantities of lung worms iu left broncbu8 and branches coutained in the 
candal third of priuoipal lobe. Kigbt bronchus not opened. Pericardiam thickeDed, 
opaque. Heart surface covered with a thin, transparent pseudo-membrane. Left 
auricle hemorrhagic. A clot distending the right heart and forming of it a complete 
cast. Center of clot pale. 

Bacteriological examination : From spleen two agar cultures made. One remains 
sterile. In the other on second day a faint growth starting from condensation water 
upwards. The latter contains clumps of swine-plague bacteria and large bacilli with 
terminal spore. Several gas bubbles iu agar. 

l^rom the pleural exudate of right lung an agar and a bouillon culture prepared at 
autopsy. On following day a large number of punctiform colonies on agar surface. 
Minute flakes in condensation water. In bouillon minute granules, representing 
clumps of minute oval cocci. In both tubes only swine- plague bacteria. ^ 

From the more recently hepatized regions of lungs which contain large numbers of 
swine-plague bacteria and some large bacilli, two gelatine rolls and two aga^ plates 
prepared. 

In the gelatine roll A two forms of colonies appeared, one with disk homogeneons, 
the other with a distinct peripheral zone. In roll B only one kind appeared. A 
number of bouillon tubes were inocnlatcd from colonies in roll B which turned oat 
to be streptococci. From roll A bits of gelatine were removed to bouillon with 
warmed platinum needle, some cultures remained sterile while others contained 
streptococci. 

On the agar plate A, large numbers of apparently identical colonies appeared. On 
plate B, a moderate number developed. Of these a few examined were made ap of 
swine-plague bacteria. 

A large rabbit inoculated with a particle of lung tissue died within 20 hours. No 
internal changes, excepting a probably preexisting fatty condition of the liver. Few 
swine-plague bacteria detected with the microscope. An agar and a bouillon culture 
from heart's blood contained only swine-plague bacteria on second day. 

No. 9. October 18. Female pig ; died last night ; weighs about 30 pounds. Sub- 
cutaneous glands of groin enlarged, firm, cortex hyperoBniic. 

One small necrotic patch on mucous surface of lower lip. Stomach ^ith fundus 
pale, pyloric region bile-stai ned. Around the cardiac expansion are about thirty 
yellowish- white, confluent, and isolated ulcers from one-eighth to one-fi^rth inch in 
diameter. They are raised above the level of the mucosa, flat on top. Projecting 
slough soft, friable; base of ulcer verj- firm, extending into muscular coat. Mucous 
membrane of duodenum bile stained ; arborescent injection of minute vessels. Mucosa 
of ileum more or less discolored and inflamed. Large intestine with walls very mueh 
infiltrated and mucosa extensively destroyed by necrotic changes. In the csBcum a 
large patch of ulceration having a peculiar gnawed appearance, surrounding islands 
of intact mucosa. On section the mucosa is found converted into a yellowish-white 
firm mass. 

In the colon patches like these are interspersed with a large number of isolated cir- 
cular ulcers with blackish, depressed surface and a subjacent yellowish, firm, thick 
base extending into the muscular coat. Besides these, there are a considerable num- 
ber of ulcers with an elevated, soft, necrotic top, easily scraped away. In lower colon 
large patches of destroyed mucosa. 

Spleen very large, friable, pulp very dark. Liver tissue apparently unaffected. 
Bile rather thick. Kidneys with parenchymatous degeneration of cortex. 

Lungs as whole much affected. In the right lung all but the dorsal third of the 
ventral lobe solid, enlarged, bright red, with large and small masses of a pale-greenish 
color disseminated through it. A portion of the cephalic lobe solid, in the same con- 
dition. One-half of the median lobe similarly diseased. The principal lobe glued to 
ventral lobe by a thin pseudo-membrane. About one-third along the ventral aspect 
solidified in masses from one-half to three-fourths inch in diameter, these masses ex- 
tending from diaphragmatic to convex surface of the lobe. The interlobular tissue 



89 

aroimd tbrae Iiepatized loaaBea diateudud witli sernm. The variotis lobes of the lefl) 
lung nre in the same condition aa the oorrespondiD^otieB of the right lung. Fleuritla 
only over the hepivtized regions in the form of a delicate uetwork. 

The trachea and broncbi cootain moch frothy mnco-ptiB. la tba left terminal 
hronchne, Horroiinded bjhepatized liseue, nre niasseBOf long worma completely ocotnd- 
iug it. 

BroncAial glands large, pale, cnntaining a variable number of amall necrotic foci. 

Bacteriological examination : From the right pleural Bac a bouillon and an agar 
tube were inoculated with platinum loop. In both only s^Tiue-plagao bacteria aiib- 
sequentlf appeared. 

Prom a more recently hop a ti zed region of the Innga two agar platea were prepared 
with a loop of tlio Bernm, in which mioroacopio examination had ahown a 
number of awine-plague bacteria. Plate A contained, after several days, a small n 
her of niiacellaneouBcolouiea and a very large numberof barely viaibie noloniea, which 
proved to be made np ot swine-plagne bacteria. On Plate B no development. 

from the more advanced diaease two gelatine rolls were prepared from a particle 
of necrotic tiasne. Koll A liijueHed. Koll B, after a week's time, contained about 
twenty-five small colonial* of tin' same charaeter, resemblhighog cholera, and one large 
colony. The former trnuBferred to agar, aud bouillon tabt^B proved to he not hog 
cholera but atreptococci. 

A rabbit jnoonlated with a bit of diaeaaed Inng tiasne died within SO honre. Organs 
not cbnii(;ed. At point of inoculation conniderable puraleut iuQUration. In blood 
and spleen a very large number of swiue-plagna bacteria, showing in atained prepara- 
tions tlie polar stain very well. Cnlturea in bouillon and on agar confirmatory. 

From Hplcen a particle of pulp naed to prepare one bouillon culture and an agar 
plate. In the bouillon the motile bog-cbolcra bacilli appeared among clumps of 
awine-plngufl germs. On the plate after several days a moderate number of colonies 
of one sixa and a very large number of colon lea of a very amall size appeared. Some 
of the former examined ate hog-cholera bacilli, the latter swine-plague bacteria. 

From particles of liver tissue tile name cultures were made, and the same mixture 
of hog- cholera and awine-plague bactoria found. 

Sections from more recent pnenmouio InfiJtration prepared from material hardened 
in alcohol show a considerable amouut of fibrin in the alveoli, in whose meshea are a 
few leucocytes and very many of the minute swiue-plague bacteria. The peribron- 
chial and interlobular lymph xpacea are distended with Gbrin and cells and contain 
very many awino-plague bacteria. 

Sections prepared from tissue in which the disease is mnch more advanced show a 
complete occlusion of the alveoli and auiall air tubes with dense cellular masses in 
which swine-plague bacteria are more or less abundant. The tissue surrounding such 
foci contains in the alvooli a moderate number of round cells, largely intermixed 
with fatty cells. Bacteria abseot. 

Ho. 10. October 19. Small male pig in poor condition, weighing 21 pounds. Died 
last night. Snhcutaneous inguinal glands very large. On section punotiform hem- 
orrhages and irregular masses of apparently necrosed tisaue observed. 

In the stomach a considerable number of single and confluent ulcers with project- 
ing, yellowish, fiiiable atougb, resting on a firm, indurated, whitish base. The mucosa 
of small intestine shows extensive arborescent injection of minute vessels. 

ContentB of large intestine, a chocolate-colored Hitnid containing much sand. 
The leaiona of the mucous membrane are about as extensive aa in case 9. The larger 
patches show more diptheritic deposit than in preceding case. 

Spleen very large, blaokisli, friable. Cystic degeneration of both kidneya. 

Lnngs ext«naively diseased. Nearly the whole o( the left lung excepting the caudal 
half of the principal lobe hepatized, and covered with a thick membranous exudate. 
This is readily peeled off in abreds and larger patches, especially dense on the ventral 
aud cephalic tobe aud adjacent pericardium. Lobes adherent U> o'l^ei a.wA'Oa«.'c%'i£ia«.- 



40 

Bions eftsily loosened. The Tentral lobe U a mottled bright red. The fmiU ftir tnbee 
occluded with Bemi-Bolid pings, easily squeezed out. This condition not obeeryed in 
tbe other lobes, excepting in the principal, in which the terminal broDchas and 
branches are occluded with plugs of lung worms and mnoo-pns. 

In the right lung, the ventral lobe in the same condition as corresponding lobe of 
left side, containing in addition numerous necrotic foci. The cephalic fifth of prin- 
cipal lobe hepatized ; the hepatization of a bright red color, with faint regular yel- 
lowish mottling. Cephalic half of the small median lobe in the same condition. 
The bronchi in the tip of principal lobe occluded with masses of lung worms and in 
part hepatized. In trachea and bronchi much muco-pus. 

Bacteriological examination : In preparations from the spleen bacteria not detected. 
An inclined agar tube inoculated with platinum needle contained in a few days a 
large number of minute apparently identical colonies. So far as could be determined 
no hog-cholera bacteria present. A bouillon culture inoculated with a particle of 
pulp contained both hog-cholera and swine-plague bacteria. 

From the liver the same cultures prepared. In the agar tnbe besides a large num- 
ber of small colonies are six larger ones. These consist of hog-cholera bacilli, the 
former of swine-plague bacteria. In the bouillon tube both germs are present. 

No inculations or cultures were made with lung tissue from this case. An agar 
and a bouillon tube were inoculated with a platinum loop from pleural exudate at 
the autopsy. In both only swine-plague germs appeared. ^^ 

No. 11. October 22. Black female, weighing 22^ pounds, died last night. Subcu- 
taneous inguinal glands indurated; cortex reddened. Some hemorrhagic points in 
parenchyma. Fine shreds of exudate on serous surface of large intestine. 

In stomach a small quantity of food. Over the entire fundus the mucosa intensely 
congested and swollen. No ulceration. Small intestine not affected. Large intes- 
tine contains a small quantity of turbid fluid. Mucosa much pigmented. In the 
caecum and upper colon a small number of ulcers with slightly projecting slough; 
lower colon considerably congested. Follicles swollen ; when compressed, a white 
curdy plug issues from a central opening. 

Both lungs diseased. In the right lung near the caudal border of principal lobe a 
wedge-shaped mass of hepatized tissue, of a bright red color. The peribronchial 
and interlobular tissue infiltrated over this region, and the pleura covered with a 
thin exudate. In the bronchi of this lobe are masses of mucus and pus in which 
lung worms are imbedded. In both cephalic and ventral lobes are masses of hepa- 
tized tissue ; in the former also a large necrotic mass. 

The two small lobes of the left lung are converted into a greenish-yellow necrotic 
mass, which cuts like firm cheese. In the principal lobe are three foci of hepatization 
two of them near the tip of the lobe, where the bronchus and branches are occluded 
with lung worms imbedded in mucus. 

Pericardium thickened, vessels injected. 

Cultures made in bouillon and on agar from pleural exudate. The bouillon culture 
contained after several days only hog-cholera bacilli. The agar tube was lost. From 
a particle of lung tissue a gelatine roll A, and agar plate B prepared. On the agar 
plate six small colonies appeared, made up of swine-plague bacteria. No colonies ap- 
peared in the gelatine roll. 

A rabbit was inoculated with a particle of lung tissue. It died in 9 days witii 
characteristic hog-cholera lesions. Cultures from the spleen contained only hog- 
cholera bacilli. 

From the spleen and liver, bouillon and agar tubes were inoculated with platinum 
wire. In all four tubes only hog-cholera bacilli appeared subsequently. 

No. 12. October 26. White female pig, weighing about 30 pounds. Died yesterday 
afternoon and placed in refrigerator until this morning. Subcutaneous inguinal 
glands enlarged, hyperaemic. In abdominal cavity some dark-colored eerum. 

One ulcer on mucous surface of lowevr lip and one on gums. Stomaoh eontracted. 




Considerable pigmentation of miiooan. OiitBido of oanLiao expansion two aloera with 
Hlightly projeotiag eloiigb. Duofieiinm very dee [ily iiigmented. Pigmentation oi- 
tenda tbrongli Binall iotestiuc. Siinilar darli pignieiitation of tho mucosa of large in- 
testine. Payer's pntch at valve converted into nunierouB amall yellowish. b1ou(;1ib 
with iuduraCed base. A few specimens of triabocephalna attacbod to m 
upper colon aboot aix small aod one larger nicer with indurated liase. Folliolea mnoh ^ 
enlarged with purulent contents eiisily expressed. Mesenteric glauda with very 
hypGTEBmic cortex. 

Both InngB adliorent to surroiiuding stractoreg. In both plenrai sacs a amall qnnu- 
tity of clouded serom. On removing the Inngs ttom thorax, the various lobea are 
fonnd bound together by exndate, the small median lobe imbedded in it and the 
diapbraf;m adherent to baseof langa, the intervening exudate being very abnudant. 
In the right iaag, both ventral aud cephalic lobea, hepatized. On section they have 
a red, granular appearance mottled with grayish linos and patcheu. In the prin- 
cipal lobe at ita caudal extremity the interlobular tissue distended with reddish 
aerom. Lung worms located here in large nnmbers. The cephalio portion of this 
lobe where it rests against the ventral lobe ia hepatized, bright red and mottled 
with whitish points and patches, differing somewhat from the necrotic foci of former 
descriptions. 

In the left lung the ventral lobe solid, resembling the corresponding right lobe. 
Loft principal like the right. Lung worms in the caudal region. 

Pericardium thickened, opaque, distended with yellowish serum. The inner surface 
lined with a partly opaqne, partly gelatinonaexndate. The heart aurface completely 



coveted with a thick, apongy pseudo- 
Spleen voiy slightly enlarged and ci 
cated m the appearance of the liver. 

Bacteriological examination : In oo' 
the lung tissue very many swinc-plague 
gelatine rolls were prepared. Tlie l.itti 
large number of minnte colonies of tho 
LS colonies. ~' 



nbrnne. (See plate x.) 
iingested. Slight post-mortem chaugoa indi- 

rer-gl ass preparations from different parl^ of 
bacteria detected. Two agar plates and two 

ir were spoiled. On tlio second agar plate a 
aause appearance anil three or four miscella- 
.e-plagne bacteria. 



A rabbit inoculated with a particle of lung ti 
apleen and blood very many swine-plague germs, 
growth in minute granules observed which this germ b 
tofore. 

At the autopsy an agar aud a bouillon cnlture wore Inoculated from each pleural 
sao. lu all four tubes only swine-plagno bacteria appeared on following day. 

Froiu spleen and liver, agar and bouillon tubes inoculated, the former with a plati- 
nnm needle, tho latter with a particle of pnlp. On the agar sntfaces a small number 
of isolated colonies appeared, made up of Bwine-plague bacteria. In the bouillon 
tnbes, besides the clumps of swine-plagno bacteria, a large spoie-bearing bacillos ap- 
peared in bottom of tubes. 

No. l:l. October 23. Black female pig w 
cutaneous inguinal glnnda enlarged, . 

Mucosa of stomach slightly discolored ii 
mocosa dark bluish ii 

Contents of large intt 
of vessels, no ulc«ratioD 

Liver tisane rather firm to the touch. On tho anrface of the right half yellowish- 
gray spots, involving from one to several iobiiles, about one to a square inch. Over 
the entire surface are disseminatod minute dots of a red-lead color, each situated in 
the center of an acinus. Bile thick and flaky. 

Spleen much enlarged, flabby ; pnlp dark red. 

In the lel't luug the dependent half of ventral lobe solid, grayish rod, faintly iriot- 
on the surface. Bronohiotes filled with plugs of thick muoo-pua. lu the central 



hours. In the 
a bouillon culture the peculiar 
8 frequently exhibited here- 



eighing 98 pounds. Died last night. Snb- 
1, pale red, innttled with gray. 
n fundus, otherwise normal. In duodennm 
::olor, minnte vessels injected aud occasionally ruptured. 

a brownish liquid. Slight pigmentation and injection 






48 

portion of the principal lobe two small hepati^ed foci. Niimerons lung worms in ter- 
minal bronchns. 

In the right lung between ventral and cephalic lobes a portion of hepatized mot- 
tled lung tissne. Somewhat back of this region a mass of necrotic tissae, separated 
from the snrronndiog tissue by a greenish-white line and covered by a thick opaque 
pleura of the same color. In the principal lobe a large wedge-shaped mass of hepa- 
tized tissue extending inwards from the lateral border several inches. Ou section it 
is dark red, mottled with grayish circles and irregular lines. The plenra mach thick- 
ened, opaque. Another wedge-shaped hepatized mass situated near oaadal tip, per- 
haps further towards necrosis than the preceding one. Pleura covering it necrosed. 
Lung worms in the terminal bronchus imbedded in mucus. 

Cover-glass preparations from the more recent pneumonic masses show very few 
germs. From the right pleural cavity a bouillon and an agar tube inocalated. In 
the former, motile hog-cholera bacilli ; in the latter about seven colonies of the same 
size composed of motile bacilli, probably hog cholera, though they appear somewhat 
too large. A black rabbit inoculated in subcutis with a particle of Inng tissue died 
in seven days. At the place of inoculation the subcutis is infiltrated over an area of 
several square inches with pus. No peritonitis ; spleen large, containing many hog- 
cholera bacilli ; necroses in liver. 

In cover-glass preparations from spleen and liver a considerable number of hog- 
cholera bacilli detected. From spleen an agar and a bouillon tube were inoculat^ 
with platinum needle. Both contain only hog-cholera bacilli on following day* 
Cultures from the spleen gave the same result. 

The lesions found in these thirteen cases may be sammarized briefly 
as follows : 

No. 1. October 12. Extensive hepatization of lungs with necrotic foci; lung 
worms ; exudative pleuritis and pericarditis. Congestion and necrosis of stomach * 
hypenemia, pigmentation, and ulceration of the large intestine; ulcers small, ulcer- 
ation evidently follicular. Only swine-plague bacteria found. 

No. 2. October 12. Spleen large. Fully four-fifths of lungs hepatized, with necro- 
tic foci; pleuritis and pericarditis; lung worms; bronchitis. Small ulcers in large 
intestine. Only swine-plague bacteria found. 

No. 3. October 12. Spleen large. Pneumonia slight ; no pleuritis. Hemorrhagic 
inflammation of stomach. Ulcers in large intestine. Both hog-cholera and swine- 
plague bacteria detected. 

No. 4. October 14. Multiple pneumonic foci in lungs. No pleuritis. Lung worms. 
Hyperaimia of stomach. Ulcers and patches of necrosis in large intestine. Only 
hog-cholera bacilli detected. 

No. 5. October 15. Scattering pneumonic areas ; bronchitis ; lung worms. Ulcers 
in large intestine (button ulcers). Only swine-plague bacteria detected. 

No. 6. October 15. Considerable hepatization of all lobes ; lung worms. Large 
ulcers in large intestine. Only hog-cholera bacilli detected. 

No. 7. October 15. Spleen large. Hepatization not extensive; pleuritis; bron- 
chitis ; no lung worms. Only Foyer's patch near valve ulcerated. Only swine-plague 
bacteria found. 

No. 8. October 17. About four-fifths of lung tissue hepatized, with necrotic foci; 
pleuritis and pericarditis. Lung worms. No ulcers in large intestine. Infarcts in 
kidneys. Only swine-plague bacteria found. 

No. 9. October 18. About one-half of lung tissue hepatized with necrotic foci ; 
pleuritis; lung worms; bronchitis. Necrotic patches and ulcers in stomach and 
large intestine. Spleen large. Both- hog- cholera and swine-plague bacteria detected. 

No. 10. October 19. Spleen large. Three-fourths of lung tissue hepatized, with 
iiecrotic foci; pleuritis; bronchitis; lung worms. Ulceration of stomach and large 



int«stiuo OS eitenBiva ns in No. 9. Both Hwiiie-plBguo and hog-oholera bactorU 
preseot. 

Nd.11. Ootober32. Scattering pneiimonlcfooi, with esteoaivencurosis; pleuritis; 
pericartlitU; limgwormH, CongeBtion of Btomaoh. Small namber of ulcers in large 

No. IS. Octol>eT25. Ante[loi(cepliHlic)ha1f of laogs ht^patized. E ste naive pleor- 
itisandpericarditiH; lungworma. Piguieutatiooof miiooaaof large in teBline. Few 
nlooca in large intetitiue ; folliclea witli purulent contente. Only Bwiue-plagne bac- 
teria preaBnt. 

No. 13. Octobarae. Pnenraonianotextenaive ; plenritis ; lironchitia ; Inng worms. 

In ail there was pueumonia more or less estensive, associated in the 
majority of oases with cellular and fibrinous pleuritis, more rarely with 
pericarditis. lu the hepatized regions necrotic masses were frequently , 

The lesions of the digestive tract varied from case to case. lu some the j 
muoosa of the stomach was hyperromic, bordering on hemorrhage ; in J 
others diphtheriticand ulcerated; in still others quite unchanged. The 1 
ieaioua of the large intestine ranged from hypeticmia and pigmeuta- 1 
tion to the most extensive destriiction of the mucous membrane. Of 1 
tlie intermediate stages may be mentioned tumefaction of follicles, with 1 
discharge of purulent contents and subsequent formation of small 
ulcers. 
The results of the bacteriological work may be tabulated as follows : 


1- 

8- 

10,. 
11.. 
1!.. 


Bple™. 


Liver. 


LnnK», 


P.e«™. 


Periuarfliani. 


Rea:«k.. ■ J 


Swfne plaeoB. 




Swlaa plBgiie. 


SirineplRBUfl- 


Swine plaenB. 


BobDecIwi™. 

Mo xwlnB 

plne<te. 
Nohogoliolera. 
Do. 

Swine plftRue 

^-"^ 

De. 

N«bDech«l6m. 


Swine plaguo. 




Swine pla!,niD- 
cholera. 






Hogchnlera.. 








Swine plaguB. 














Swine plagne. 




Swipe plBETlB 






ami aVi^pto. 
cotcl. 
Swine plngne. 




1? 

HogdholerB.. 


plaKue. 

cbolsra. 
HogcholBTB.. 
















Swino pjaffue- 








1 


1 1 




plague. ' 


1 

aw 
eh 

1 


fc will be observed that iu six cases (Nos. 1, 2, 5, 7, 8, and 12) only * 
ne-plague bacteria were detected; in three (Nos. 4, 6, 13) only hog- 
lera bacteria, and in four (Nos. 3, 9, 10, 11) both were found. In 
eral I would not place too much stress on the absence of either kind of . . 
■teria, because there is no reason why if both iiatUosfcuKc. a^tSft* %it«> J 



44 

present they sbonld not aft^r a time invade every Animal, nnleas the 
presence of one disease, sucli us swine plague, would opi>o8o the 
BioQ ol' bog cliolera iu tiie eume animal, a hypothesis for which we hare 
DO supporting facts. If we turn to the positive evidence we And that 
in ten out of thirteen animals the same virulent swine -plagne bacteria 
were found. We have, in other words, bacteria pathogenic in pigs, as 
we shall presently show, which travel from animal to animal and pro- 
duce a more or leas estensive pneumonia with plenritia. These facts 
arc in themselves BuQicient to separate swine plague as a distinct dis- 
ease from hog cholera. 

In those cases thoroughly stndied, such as Nos. 1 and 2, hog-cholera 
bacilli were probably entirely absent. A glance at the table will show 
that when they were detected they were always found in the spleen. 
In Nos. 1 and 2 only swine-plague bacteria were found iu tlie spleen. 
The same may be said of No. 12. Why the hog-cholera bacilli should 
have been in these animals and not appear in any of the uumerons cal- 
tnrea made is certainly incomprehensible. 

Perhaps the best evilence, aside from inoculation, that Hwine-plague 
bacteria are the cause of the pneumonia is deducible from the bacte- 
riological examination of the lungs and pleura. In only two later 
oases were hog-cholera bacilli obtained" from the pleura. In one (No. 
13), the lung disease had advanced to caseation, and it accords with 
former experience that m such cases swine-plague bacteria are gone, 
and if hog-cholera bacilli are in the animal they are certain to appear 
in these dead lung masses, and hence in the pleura) cavity. In those 
longs which were extensively hepatized, but in which necrosis had 
not advanced far, the hepatized tissue was practically a pure culture 
of the swine-plague bacteria. The cause of the intestinal lesions mnst 
remain a matter of doubt, although their nature combined with tlie 
presence of hog-eholera bacilli in the herd would lead us to regard them 
as due to the latter. 

As to the origin of this mixed ontbreak, nothing positive conld be 
learned of the former history of the herd. As it was made up of two, 
possibly three lots, it may be assumed that one lot brought one germ 
and another lot the other. This hypothesis gains force from the gieat 
variation iu the extent and character of the lung and intestinal lesions. 
Meanwhile it must be remembered that only one-third of the herd came 
under observation, owing to the rapidity with which the animals suc- 
cumbed and the somewhat tardy information Cflncerning the outbreak 
which reached us. 

THE PRODUCTION OF DISEASB IK SWINE ASD OTHER ANIMALS WITH 
THE SWINE-PLAGUE BACTERIA FROM THIS OUTBREAK. 

The bacteriological notes already given indicate a virulent variety of 
these bacteria, inasmuch as rabbits succumbed to a subcutaneous in- 
oculation of a minute dose withiu 20 hoars. The following tests on 



45 

four pigB were equally strikiDg. The culture used was derived from 
case 2 by inoculating a rabbit with a particle of luug tissue. The 
culture from tlie apleeu of this rabbit was again tested about a month 
later on a seooud rabbit. The agar culture from tbis animal was used 
to inoculate six agar tubes. From these, when 2 di^s old, the surface 
growth was washed down into the condensation water with sterile 
bouillon and the turbid liquid transferred to a sterile test tube. With 
tbis the following inoculations were made : 

So. 272, 2 cubic centimetres Bubcataneously, one-balf into each 
thigh. 

No. 273, one-balf uubie centimetre into right lung, through chest- 
wall, between fifth and sixth rib. 

iTo. 274, 1 cubic centimetre into abdomen. 

No. 275, Ij cubio centimetres into right luug. 

These pigs were all alike, Essex grade, 10 weeks old, and weighed 
about 40 pounds each. The inoculations were made November 16, 5 
p.m. 

So. 272 did not stiaw an; iU eSeeta except amall tumors at tbe iilftoea of iujuction. 
It was killed December 9 and fuuuil uonual. 

No. 273 was very sick on the following day. It breathed with difficulty and re- 
fused to rise and eat. On the fourth day there was some iiuprovenient. The aoimal 
begaD to eat. The improvement coutitiued and oti December a (16 diiys after inoen- 
lation) it hiul appareutly fully rocovered. Ou this day it was killed for examination. 

About 100 cubic centimetres pale yellow seruni in abdominal cavity. Diaphragui 
pressed downwards and very tense, as viewed from the abdominal side. Lungs ad- 
heront to oheat-wall and diaphragm. Both pleural saus converted Into large aliacess 
cavities, Ihewallsof which are formod by tbe diuphragm, tbe « heat- wall, and the con- 
vex Burface of the Inngs, These walla ate very much thiukeued and covered with 
a pulpy yellowish- white layer of pus. Tbe cavity is distended with a tnibid, milky 
fluid. Longs moch oompresscd, along dorsal border collapsed. Small median lobe 
GoUapBed. 

Pericardinm adherent to heart surface hf means of fibrous bands. Ferioardial sac 
contains a small quantity pale yellowish turbid liquid. 

Inteatiual tract normal. Liver with many lohules either entirely or only centrally 
congested. tJerons surface facing diaphragm slightly roughened. 

At this time no swine-plague bacteria were found in the spleou, as the cnltaiea 
made therefrom with particlea of pulp remained sterile. 

No. 274 was found dead early next morning, i. e., within 21 hiiurs after inoculation. 

The superficial ingninal glands much reddened. The abdomen contains about 100 
cubio centimetres of clouded, straw-oolored serum. The serous surface of tbe 
variooa abdominal organs exposed by reflection of the abdominal walla covered with 
> thin layer of pale yellowish, friable exudate, thickest on the liver. The exudate 
also found between the ooila of intestines. In both pleural aacs from 50 to TIj cubio 
centimetres of turbid serum. Pleuritic exadate on the veutral third of the right 
lung, ijiuiilar exudate ou the t>ericardiuni. Lungs nurmnl. Digeative tract normal 
so far as the mncous membrane is concerned. Tbe various lymph glands of thorax 
and abdomen slightly reddened. Liver, spleen, and kidneys not afiectod. 

Only the spleen of thb case was examined for bacteria. After scorchiug the sur- 
face an agar and a bouillon culture inoculated with platinum wire. Ou the agar 
surface about lOO isolated colonies from I^ to 3 millimetroa in diameter appeared ou 
the followiug day, all alike and so far as examined made up of awiuo-ploguc bacteria. 

flbonilloQ oulturu likewise proved to bo a pure culture of the iui'iGt,e4'aaR.\jOT'i.'fc, 



1 



d 



46 



No. 275 became very sick after the inoculatioD. It refused to get op and eat, and 
breathed with difficulty. It was found dead November 19, i. «., between 2 and 3 
days after the inoculation. 

Skin not discolored. The cut subcutaneous vessels exude drops of dark blood. In 
the abdomen a few elastic threads of coagulated exudate stretched across coils of in- 
testines. ^ 

In right pleural cavity about KK) cubic centimetres of blood-stained semm. Lnngs 
adherent to ribs by means of a thick, soft, easily removable exudate. Liobes of right 
lung glued to each other and to pericardium ; they are not enlarged. The pleura of 
the ventral half of principal lobe is converted into a thick, wrinkled, and bleached 
layer; beneath it the lung tissue is hepatizod. The dorsal portion of this lobe, still 
air-containing, covered with patches and shreds of exudate. The cephalic and ven- 
tral lobe solidified, not enlarged ; grayish-red on section. 

The left lung likewise covered in part with pleuritic exudate. The ventral two- 
thirds of principal lobe covered with a thick pseudo-membrane and hepatized, very 
firm ; on section, red, mottled with gray. The ventral and cephalic lobes collapsed, 
covered with exudate, which extends to contiguous pericardium. (See plate vi). 
The entire diaphragmatic portion of pleura of both principal lobes and median lobe 
converted into a wrinkled, necrotic mass. Pericardial sac contains much reddish, 
turbid fluid. The surface of the heart covered with a whitish, firm, roughened exu- 
date. 

Stomach contracted ; contains a small quantity of bile-stained liquid. The mnoosa 
of the fundus bluish-red, swollen. The whole covered with a layer of viscid bile- 
stained mucus. The remainder of digestive tract free from inflammation. 

In the liver the central region of acini dark brownish red, the outer portion pale 
brownish. 

The presence of the injected swine-plague bacteria in the organs of this animal 
were determined by the following cultures : 

From the spleen, in which no bacteria were detected under the microscope, an agar 
tube inoculated with platinum wire and a bouillon tube by adding a particle of pulp. 
The bouillon tube became clouded with swine plague. The agar tube remained 
sterile. A rabbit inoculated subcutaueously in the ear with a platinum loop dipped 
into the bouillon culture died within 20 hours. In blood and spleen very large num- 
bers of swine-plague bacteria. In cultures from these organs only these germs pres- 
ent. 

A small area on the hepatized left principal lobe scorched, and a small particle cat 
out with flamed scissors. From the serum filling the cavity thus formed, which con- 
tained large numbers of swiue-plague bacteria, one gelatine roll, and from this two 
agar plates prepared. The roll remained free from growth ; also one agar plate. 
On the other appeared a large number of minute colonies and several large colonies 
of hacillus suhtilis. The former were identified as swine-plague colonies. From the 
left pleural exudate an agar tube was inoculated. Abundant growth of swine-plagoe 
bacteria on the following day. 

From the hepatized region of the left principal lobe portions were placed in alco- 
hol and subsequently sections prepared. The alveoli and small air tubes densely 
packed with masses of cellular exudate. The interlobular tissue distended with a 
network of fibrin and a scanty number of leucocytes. In the contiguous, still pe^ 
vious areas, some air tubes were occluded with cellular plugs, and either around these 
or independent of them were isolated groups of alveoli occluded with round cells. 
Swine-plague bacteria were present in enormous numbers both in the parenchyma 
and the interlobular tissue. They were densely and uniformly sprinkled around and 
between the cells, in some places forming dense zooglcea. They were much smaller 
than in cultures, being just visible at 500 diameters. (See plate xi, figs. 2 and 3.) 

These iiioculations show that these bacteria injected sabcutaneonsly 
have little or no effect, bat when introduced into one of the large » 



roaa cavities severe inflammatiou is aroused followed by speedy deatb. 
lu No. 275, the injection iuto tbe right lung led to a typical pleuro-pueu- 
iiionia of the left luug, such as was encountered iu Ibo outbreak from 
which the bacterift were isolated. 

These bacteria were fatal to mice and guinea-pigs and to pigeons iu 
large doses : 

Deeeniber 13. — Two mice iooculated nnder akin of Laclt with a loop of growth from 
an agar cuituro ODB day olil. Both dead uext moniiug, with spleen much aBuUen 
ami ciititaitiliig large nuoiberB of the inoaulatod hacteria. From the apleen of one an 
agar ttaH a bonillou culture wore madu. The bouillun liecume faiutly climded; on 
the agar Diiinerons oonflaentculuuieB appeared. Only awiiie-plagnebactdria detected 
in these oiiltiireB. 

From the same culture a gninea-pig waa iuoculated subcntaDeoualy iu the same 
v/aj. The guinea-pig lived 12 daya. No leaious except a fatty condition of liver 
fouud at uiitupey. A tube of agar to which 2 dropa of blood were added remained 
sterile. 

At the same time two fonla and two pigeoua were inoculated, ooe fowl luid oue 
pigeon with a loop of the agar culture aubcutaneoualy and one fowl and one pigeon 
with 1 ouhio centimetre of a, peptone bouillon cultnre one day old. The needle of 
tlie ayriuge penetrated the Hnper&cial mnacular layer of one pectoral muscle. 

Both fowls remained well, also the pigeon iuoculated with the loop. The other 
pigeon dead next day. Ou the right pectoral regiou the aubcotis was infiltrated aud 
_ of a reddish-yellow color, the aubj aeon t tnu ecu lar tissue discolored to a depth of one- 
fourth to one-half iuch. Lungs cungeated, other organs normal. In the blood num- 
erous 8 wine-plagUQ bacteria giving the polar stain; in the liver very few. 

In April, 18Q1, about 1| years after these bacteria had been obtained from thia oot- 
break, the following inoculations wore made tu determine bow much of their -viru- 
lence had been lost by cultivation. 

ApHl 13. — With a loop rubbed over an agar culture 4 daya old, a large gray rabbit 
was iuoculated by iuaortiog the loop into an incision on the ear made with flamed 
lancet. Gahbit dead next morning. Iu blood aud spleen awine-plague bacteria in 
moderate abundance. 

Api'ilZl. — Two guinea-piga weighing IJ pounds each received a Bubcntaneouaiujeo- 
tion of 0.075 and 0.15 cubic centiroetres of a turbid suapeuBion of swina-plague 
bacteria from an agar culture 1 day old. 

The guinea-pig which had received the largest dose died in 2G hours. At the place 
of iujectiou alight yellowish infiltration of aubcutia. No peritonitia. In both pleu- 
ral sacs a large quantity of a grayish, partly gelatinoua efi'usion, containing immeuse 
nnmbeni of bacteria. Pericardial sac similarly involved. Both Innga dark bluish 
red throughout; tissue still Hoats. 

The other gninea-plg very aick for several daya, recovered, and was kiUed on the 
eighth day. At the place of iojectioD a minute ulcerous opeuing from which poa 
con Id bo pressed. In the subeutis considerable rather firm iuliltratiou, surrouudcd 
by patches of blood extravasation. Internal organs not afisoted. 

VIII. 

In November, 18S9, au outbreak of swine plague came to the notice 
of the Bureau, which, in some respects, has a quite remarkable history. 
The information giveu below was obtained by Dr. Kilborne. 

Aq educational iiistitutiou near this city was in the habit of keeping 
on its iDclosure a small number of swine iu pens which were arranged 



iii.tlie manuer iudicate«l in tbu figure. The slope of tbc groand was 
from yard I to yard 3, aud from yard 5 to yard 3. 




ro.z. 


— 


— 


Yo.3. 




Yaho j. 


PC.H.Z. 


PfJ4.3. 


Yd. 4. 

r 






Pen. 4. 




PEK.h 


PSN.S. 


Yd.S. 



In Sepbtiuiber a boar, 5 moutlLS old, died in imjii 1. Tliere bad been 
uo diBease on the place 3 yeara previous to this occurrence, aud no recent 
purchase of pigs. In the latter part of October ten piga, 2 inuutbs old, 
were purchased, five placed in pen 1, and five in pen 5. At tbis timea 
60W in pen 2 bad four pigs, all of nbicb died in a few days, while the 
sow, although sick for a time, reoovered. 

lu x)eu 3 a sow becatue sick very suddenly Kovember S, aud died next 
day. A litter of seven pigs, 7 weeks old and small f i- their age, died 
within 4 days after the deatli of the sow. Of the^e, five came uuderonr 
observation (Nos. 1 to 5 iuclnaive, of the autopsy notes). These five, 
after a very careful examination, proved to be cases of swine plague. 
While the recently purchased pigs iu pen 1 remained unaffected, those 
in pen 5 began to die at the same time that the young pigs iu pen 3 
were dying. Thus two died November 9 and one November 10. One 
of these was carefully examined, and to oar surprise the disease was 
found to be bog cholera, as the autopsy notes (No. C) clearly show. 
The remainder were taken to the Experiment Station. At the same 
time there were in pen 4 two pigs about 5 mouths old and oue old soy. 
One of the pigs, sick November 12, was transferred to the Experimeat 
Station, where it was found dead on the followiug morning. This case 
also was one of bog cholera (Case 7). By feeding the viscera of these 
two pigs to fresh pigs an outbreak of hog cholera was produced, which 
was subsequently utilized in a series of experiments on vaccination, as a 
means of exposing swine which bad been vaccinated beforehand. 

On inquiry over a month later, we were informed that no further 
losses from swine diseases bad been sustained. 

In the tbllowing pages are given the notes of the autopsies and 
bacteriological examination of tiie litter of small pigs which died in pen 
3. They are all the more interesting in that the disease was swine 



plaguti uDGomplicated with liog cliolera. The autopsy notes of tlie two 1 
hog-cboltira cases from pen 5 and pen i are appended, to complete tho 1 
liistory of tbia remarkable outbreak. 

Nuvember 11, VSiQ. — Pig No. 1, white female, weighs about 15 pounda. Died li 
night, ConsideiaLlo ledileiiiug of the ukiix over the veutral uapeot of the l)ody. 

Stouiacli coutaiua a suiaU quantity of a yellowiidi viaoid liquid. Fundus covered 
with niuuua aod iuteusely reddened aud awoUeu. In the large in toatiue, mucosa 
olightly dJHcoliired ; ia a few places aumewbat reddened. No necrosis or njcoration, 
Gtaudu uf the ineno-culon ealarKed, iudurated, pale. 

About cme-half of both lungs bepatizeil, tlie disease limits to thu ventral or de- 
pendent half. The various lobes adlioreut tu oue another, to puricuidiuin and dia- 
phragm by nieana of a thin, papery psen do-mum brane, which is removable. The hepa- 
tization ia very firm ; on aevtUiu, grayish red or red mottled with gray. Near the roote 
of tlie lobes, also on diaphiag matte sarfai^e of tlie lungs, are considerable nauibeta of j 
small necrotic masses, surrounded by a bluish zone. In the trachea and bronchi, red- ] 
dish froth; in the distal extremitiesof both bionQhi,lungworms imbedded inmucso. I 

S!>leea small, uot congested. Liver exceedingly lirni to the touch. Surface sot 1 
smooth, owing to acini slightly projecting above interlobular tissue. 

Bacteriological examination : Preparations from hepatlKud lung tissue contain 
immense nnmber of very minute oval bacteria. Those from the pleural exudate c< 
tain a smaller nnmber. On one of the principal lobes the pleura was scorched o^ 
the dideased portiou, and with a particle of tissue from within the scorched area 
gelatine roll A, and two agar plates B, prepared. In the gelatine roll appeared, after J 
a few days, a lurge nnmber of barely visible colonies. A week later, besides these, a, I 
smaller number of colonies, 4 to fi times larger than the preceding, had appeared, f 
Owing to the large nuoihtr of colonies microscopie examination not successfnl, J 
Minute bits of gelatine were removed at diftsreat intervals with warmed platinnin j 
wire and transferred to peptone bouillon. In these tubes only swine-plague gunue ^ 
appeared. The larger uoloiiies may havebeon streptococci, as they failed to develop In J 
the bouillon. Both agar plates, after several days, contained a large onmberof idea- | 
tiual quite small colonies, which were found to be awinu plague colonies by m 
BGopic Biamination aud transfer to bouillon. In order todeteroiiuewhethcr anyother, J 
bacteria were present, two bouillon tubes were iouculated direetly from the lungs, \^.M 
piercing them with a platinum wire and transferring this to the bouillon. In botfa.'.f 
tubes only wiine-plagiie baoKHa appeared. 

A rabbit inoculated at the sanie time with a particle of lung tissue died in S days. 
The subcutaneous tissue over abdomen exteuaively thickened by a purultmt and gel- 
atinous infiltrate e.>(tonding over part of thorax. The nbdomtual walls are thickened 
and glued to the viscera. These latter covered with a rather firm elastic exudate, which, 
dips down between the coils. The serosa is sprinkled with punctiform euchymoa 
Spleen small ; thoracic organs not affected. In the abdominal exudate a: 
numbers of oval bacteria,atainiug rather feebly. These uot detected in splee 
blood. An agar tube inoculated from the spleen contained but a single swiue-plagnft jl 
colony. A gelatine culture from the blood shows in the tracli of the needle about ■ 
12 minute round colonies. In a bouillon cidtnre from the peritoneal exudate only! 
swine -pi ague bacteria developed. 

From the plcnial exudate of the pig an agar and a bouillon tube inoculated a 
antopsy. lu the former a considerable number of isolated and conflnent colonies oJ 
swiue-plague bacteria appeared. The bouillon culture likewise ooutains only si 
plague bacteria. 

From the spleen pulp, in which no bacteria were detected, a particle placed in an 
agar and a bouillon tube. Both were sterile on the following day. On the third day 
&Iut clondinoss of the bouillon, which contained only swine-plague germs. lu t^b«> 
kgar tulie the condensation water was clouded, and a grayiali TQ6m.\«B.'n« ala^'wiU.tawa, 
it ascending along agar surface. Oulyswine-plaguebatteiiaieX.eo^ftiisi'ij'Oiafe^^'^'^^* 
16J4 i 



50 

PoHions of Inng tissae from different lobes, hardened in aloohol, were examined. 
Sections from recently affected long tissae, bordering on normal tissae, showed the 
alveoli to be filled in some lobales with blood corpuscles and fibrin ; in others there 
was, in addition, a filling up of scattered alveoli with round cells. In still others the 
alveolar capillaries were greatly distended with corpuscles, almost occlading^ the al- 
Teoli. Imbedded in the fibrinous plugs of the alveoli were colonies of minute cocci, 
almost every alveolus containing one or more such colonies. In sections from tissues 
in more advanced stages there were, in addition to the more dense cell infiltration, 
large masses of the minute bacteria occupying the alveoli in some portions of the 
section. Any regularity in the distribution of these bacteria not observed. 

No. 2. Examined at the same time. White female, weight 15 pounds. Skin on 
ventral aspect of body moderately reddened. Subcutaneous inguinal glands hy- 
peraemic. 

Stomach contains a small quantity of turbid liquid. Mucosa of fandos consider- 
ably reddened. In the small intestine the vessels of villi appear injected, especially 
in duodenum. lu the caecum and colon the entire mucosa has an intense pnrplish hue, 
shading into a wine color. This most marked in the cajcum and upper 4 or 5 inches 
of colon, where tbe epithelium appears necrosed. The inflammation gradnally dimin- 
ishes and disappears in the rectum. 

Exudative pleuritis as in case 1 ; tbe pseudo membrane as thick as heavy paper. 
About two-thirds of right lung hepatized. The cephalic and ventral lobe entirely 
solidified, also adjoin iug half of the principal lobe. In the caudal portion of the latter 
several hepatized foci. Lung worms iu terminal bronchus. The tip of cephalic lobe 
completely necrosed. The ventral lobe contains large, yellowish- white, homogeneons 
foci of dead tissue. Median lobe completely hepatized. Through it are disseminated 
necrotic foci. 

In left lung, principal lobe entirely hepatized. Hemorrhagic, grayish-red, and 
grayish lobulss found on the same cut surface. Ventral and cephalic lobes merely 
congested. Pericardium thickened. 

Spleen small, pulp darker than normal and softened. Liver as in No. 1. Bile very 
thick, dark-colored. 

Bacteriological examination : Au agiftr and a bouillon tube were inoculated each 
with a particle of spleen pulp. The agar tube remained sterile. The bouillon be- 
came faintly clouded on the second day and contained only swine-plague baeteriab 

The hepatized lung tissue and pleural exudate both show presence of swine plague 
germs; the lung tissue contains immense numbers of them. With a bit of the latter 
a gelatine roll A and agar plate B prepared. In the gelatine roll, a considerable 
number of very minute brownish colonies appeared within a week. They were aU 
alike. Several transferred to bouillon at intervals and the resulting cultures care- 
fully examined. Only swine-plague bacteria detected. The agar plate had a moder- 
ate number of colonies, those growing on surface from 2 to 3 millimetres in diameter. 
These also proved to be swine plague when examined and transferred to bouillon for 
further identification. 

At the autopsy an agar and a bouillon tube were inoculated from the right pleural 
cavity. On the agar appeared a large number of isolated and confluent colonies all 
apparently alike. Some of these, as well as the growth in the condensation water, 
were examined and found to be swine-plague bacteria. The bouillon contained also 
a streptococcus and a bacillus, imparting a sour smell to the culture. A rabbit in- 
oculated with a particle of lung tissue died in 6 days. The subcutaneous infiltra- 
tion and the peritonitis precisely as in the rabbit inoculated from No. 1. The spleen 
contained scarcely any, the blood few, and the peritoneal exudate an immense number 
of swine-plague bacteria. Agar cultures from exudate and blood and a bouillon cul- 
ture from the exudate contained only swine-plague bacteria. 

The presence of swine-plague bacteria on the inflamed mucosa of c»cam was dem- 
onstrated by inoculating a rabbit with a particle of mucosa which had been washed 



»• c •■ 



61 

in sterile water. Rabbit died in 3 days with conaideruble local infiltration, bat no 
peritcmitiH, An agar uulture from sploon with plfttinmn iieedlo remiiiiied Bterile. A 
bouillon culture from blood became clouded with Hwiuo-plagiie bacteria. To further 
teat this geno, one-eigbth cubic centimetre of this bouillon cultiire 7 days old was 
iujected Buboutaneoualy into a rabbit. It lived 11 days. There was exteneivo purn- 
lent infiltration of the auboutia over abdomen and thorax. Internal organs normal. 
But one (bonillon) tube iuocniatcd with particle of liver tisone. Thia remained clear. 

No. 3 examined on sams daj. White female weighing 18 pounds. Died last night. 

Veutral aspect of bod; considerably reddened. Stomach as in preceding cases. 
Mucosa of duodenum very much reddeued [ the remainder of the small intestine nor- 
mal. Mucosa of cajouni and colon not quite ao intenaely intlamed as in No. 3. Indi- 
cations of a yellowish, soft exudate appearing in small masses as part of the feces. 
Its microscopic characters not determined. 

Double ex □ dative plenritis, the exudate, thick on diaphragm which firmly adheres 
to Innga, very alight ou convex surface of lungs where it appears as a rongbeuing or 
a very delicate membrane. The varions lobes glued to each other and toperioardiura. 

In the left lung the two smaller lobea (ventral and cephalic) iu a coudition ofpalo- 
red hepatization ; very slightly enlarged. In the principal lobe four or five foci of 
dark-red hepatization imbedded in normal tissue, on section marked with grayish, 
irregular lines. These masses are elevated slightly above the surrounding tliisue and 
covered with a thick, opaque, greenish- white pleura. In the right lung both smaller 
lobes bepatized, larger than the corresponding Left lobes, very firm to the toaeh. The 
cut surface sprinkled with minute grayish masses. In the principal lobe the bepa- 
tized masses are dark red in color. The small median lobe enveloped in oxildate and 
hepatized, the cut surface grayish red. 

In the bronchi a small quantity of reddish, frothy liquid. In the right terminal 
broDcbuH lung worms. Bronchial glands very large, firm, yellowish white. 

Pericardium inflamed, opaque. In left heart a firm washed clot imbedded in a 
dark, soft coagulnm. The right heart distended with a dark, aoft coagulom. 

Spleen small, dark-colored. Liver and bile as in No. 2. 

Bacteriological examination: From the spleen an agar and a bonillon tube inoc- 
ulated with a particle of pnlp. After several days a grayish growth, spreadiii;: from 
bit of spleen, composed of rather targe cocci. The bonillon tube at this time also 
clouded ; contsiaa only awine-plague genus. 

Two similar cultures prepared from the liver. Iu the bouillon tube only swine- 
plagno bacteria appeared. On the agar surface three colonies present, ouu of these 
a ohtomogene, the others large spore-bearing bacilli. Iu the tnrbJd condensation 
water the same large bacilli and swlne-plague bacteria nitcrmiiigled. In cover-glatia 
preparations from spleen and liver no germs could be detected. 

From the light pleural cavity an agar and a bouillon tube inoculated. Bolb re- 
Diaiued sterile. 

From the modt recently boputized lung tissue, which contains large numbers of 
Bwiue-plague bacteria, a gelatine roll A and an agar plate B prepared. In the galatioe 
roll colonies appeared answering to the description given for those under case I. 

The bouillon tubefi prepored from the colonies contained no hog-cholera germs ut 
anytime. Swioe-plagoe bacteria and possibly streptococci were present, although 
this is somewhat doubtful. The agar plate B remained free from growth. A bouil- 
lon tube inocculated with a platinum needle thrust into the hepatiitcd lung remained 

A rabltit inoculated with a particle of lung tissue snccnmbed to the disease in S 
days, with extensive subcutaneous purulent infiltration over abdomen. No peritoni- 
tis. Cover-glass preparations and cultures from blood and spleen are negative. 

From this lung aeotioos were cut from portions of one priuci[>al lobe hardened in 
aJoohol. The alveoli were nearly all occluded by round cells, among which in a oer- 
ti^n unmber of alveoli large masses of the very minute swlne-plague bacteria ciaal&. 



62 

be detected. The small air tubes likewise filled with densely packed cell masses. The 
interlobular tissue in a state of iullammatory oedema. 

November 12. — No. 4, small female, weighing about twenty pounds. Died last 
night. Ventral surface of the body moderately reddened. Considerable quantity of 
subcutaneous fat. Lymphatic glauds in groin slightly enlarged and reddened. 

One ulcer at base of left lower front tooth. Stomach contracted and contains a 
small quantity of liquid resembling tomato juice. The mucona of fundus over an area 
3 inches in diameter of a dark wine-red color ; the hypenumia extends through entire 
mucous layer. On the surface a very delicate, easily removable pseudo-mgftibrane. 
Mucosa of duodenum pigmented and bile-stained. In lower ileum some patches of 
punctiform ecchymosis. In large intestine feces adhering rather firmly to mucosa, 
which is reddened and pigmented in spots and patches and somewhat rough to the 
touch. 

In thracic cavity lungs covered with false membrane and in part adherent to chest- 
wall and pericardium. On removing them, the pleuritis and hepatization found 
nearly as extensive as in the preceding case, t. e.y the greater part of both small lobes 
in each lung hepatized and exceedingly firm ; in the principal lobes disseminated foci 
of hepatization both of the grayish-red and the hemorrhagic type. Lung worms not 
detected. In the air tubes of the ventral lobes cylinders of whitish pus. In the large 
bronchi reddish frothy liquid. Pericarditis as in preceding case. On the epioardium 
a very delicate pseudo-membrane. 

Liver tissue very firm to the touch ; bile thick. Pyramidal portion of kidneys dark 
red. Spleen small, somewhat darker colored than in normal condition. 

Bacteriological examination : Cover-glass preparations of the pleural exudate show 
a moderate number of swine-plague bacteria. In the lung tissue there are immense 
numbers of these bacteria, with an occasional large bacillus amongst them. From the 
right pleural cavity an agar and a bouillon tube, from the left an agar tube inoculated 
at the autopsy. In these tubes a considerable number of identical colonies appeared 
made up of swine-plague bacteria. In the condensation water of an agar culture 
from right pleura occasional streptococci to be seen. The bouillon tube became uni- 
formly clouded with swine-plague bacteria. After two weeks a few very large colo- 
nies of strange bacteria had developed in both agar tubes. 

With a particle of lung tissue a gelatine roll A and an agar plate B prepared. HoU 
A broke ; plate B showed in a few days about 50 colonies, evidently alike. Those 
examined and transferred to bouillon consisted only of swine-plague bacteria. 

A rabbit inoculated with a particle of lung tissue remained unaffected. Another 
rabbit received a subcutaneous injection of one-eighth cubic centimetre bouillon from 
an agar colony of lung plate. This rabbit died in 13 days with a very large abscess 
at the point of inoculation. 

In the spleen of pig no bacteria were detected with the microscope. In the liver 
several germs resembling swine-plague bacteria were observed. With particles of 
liver and spleen tissue two agar and two bouillon tubes were inoculated. Only the 
bouillon tube from the liver became fertile and contained a diplococcus ; no swine- 
plague bacteria. 

Sections from the lung tissue hardened in alcohol and stained in various ways weie 
carefully examined. In the same section were lobules in which the alveoli contained 
fibrin and very few cells, others in which much desquamation of the epithelial cells 
had taken place, and others in which the alveoli were occluded by dense cell masses. 
In some places the septa had apparently disappeared and a continuous plug of densely 
massed cells extended through a number of continuous alveoli. The small air-tubes 
were likewise filled up with cell masses. The interlobular tissue distended with 
serum, the lymph channels similarly distended and containing masses of leucocytes. 
In all alveoli excepting those containing only the desquamated cells, the very minute 
oval swine-plague bacteria are present in immense numbers^ disseminated singly 
through the (edematous tissue and in large zoogloea amongst the cellular masses. 



63 

November 13. — No. 5, aiiiall wiiite male, wcif;ht uIioilI, 10 pmirrln. Died Innt night. 

In the digeativB tract of tliia case notbiug abuurmal eicepling n foiatnTbat blnish 
cnlorntion of ttiu mucosa of large intestine and bwuIUd^; of the solitary folliclea, tbe 
oonteuta of irbicb can be expressed tbrongti a eeutral opeQinfr, 

About ooe-tblrd of Lbe eutire long tissue hepatized. Tbe dieeasa involves the ven- 
tral third of all tbe lobes, excepting the left cephalic, 'which in free from pnenmoula. 
The median lobe cooipleteiy aolidi fled and eonlaiuing two necrotic tbci. A thick 
psendo-memlirane covers tbe plcnra of the diseased areas. In the bronchi and 
branobes of the principal lobes nnmeroos plugs of lung worms imbedded iu luucus. 
Tbe bronchi of the ventral lobes occlnded by cylindrical masses of mucus and pus. 

Bacteriological examination: An agar tube inoculated from the right pleural cav- 
ity at the autopsy contained subsequently 5 colonies of swiue-plagne bacteria. 

Cover-glass preparations of diseased lung tissue show large nnubers of pus corpns- 
clea, amongst these small oval bacteria, probably swine plaguo, and occasional chains 
of streptococci. A gelatine roll cnltnre A and an agar plate B were made from par- 
ticles of long tlssne. In rull A there appuurod, after a week, about onebnndred colo- 
nies of Ancilf us oolj, twelve colonies ofaalowly liquefying chromogene, and a very large 
number of colonics just abowiug a disk under the microscope. Particles of gelatine 
containing these minute colonies were removed to bouUion, butno development took 
place. On the agar plate about ten colonics of a wine- plague bacteria appeared, which 
grew quite large, owiogto isolated position. Transferred to a boullion their swine 
plagne nature confirmed. 

With a particle of inng tissue a large black rabbit inocnlated. Deadiu five days. 
The snbcutis was estonsively infiltrated and thickened as in previous cases. Peri- 
tonitis absent. Spleen barely enlarged. In cover-glass preparations from spleen and 
liver no bacteria observed. In an agar culture from blood thirty swinu-plague colo- 
nies appeared. After a week a fleshy, whitish growth composed of large motile bacilli 
starts from condensation water upwards ou agar surface. In an agar culture ironi 
the tiver-a considerable number of swine-plagiie colonies appeared. In a bouillon 
cultnre from apleen only swine-plague bacteria develape<]. 

With particles of apleen pulp of the pig an agar and a bouillon tube inoculated. Tbe 
bouillon becaoio very turbid, greenish, fluorescent and contaiued a small motile bacil- 
luB. Plate cultures from this proved the bacillus a liquefying flnoiescent bacillus. 
In the agar tube a growth started from particle of spleen down the inclined surface 
and subsequently imparted to the agar a greenish tint. The aame bacillus as that 
found in the bouillon cnltnre present. No swine plagne bacteria detected. 

In all five pigs specimens of tricbocephalus wore attached to mucosaof caecum and 
upper colon. 

The following tables give a brief snmniary of the facts obtained: 

Pig No. 1. November 11, oue-half of luugs hepatized ; some necrotic 
foci. Exudative pleuritia, pericarditis. Lung worms. Oatarrhal inflam- 
mation of stomach. Ocly swiue plagne bacteria present. 

Pig No. 2. November 11, two-thirds of lunga hepatized; many necrotic 
foci. Pleuritis, pericarditis. Long worms. Hypersemia of stomach. 
Intense hyperiemia of large intestine, 

Pig No. 3. November 11, one-half of lungs hepatized ; pleuritis; peri- 
carditis; lung worms; hyperiemia of stomach and large intestine. 

Pig No. i. November 12, one-half of lungs hepatized; pleuritis and 
pericarditis; bronchitis; liyper;emia of stomach, of large intestine 
Blight. 

Pig No, 5. November 13, one-third of langs hepatized; plenritia 



J 



54 

bronchitis ; lung worms ; swelling of solitary follicles of large inteS' 
tine, contents expressible. 



Pig 
No. 


Langs. 


Plenra. 


Spleen. 


Liver. 


Intestines. 


1 
2 
3 

4 

5 


Swine plague Swino plasrue SwinA nlamiA . 




Swine pla^e. 


.. do - '...do 

...do Neifative 

...do 1 Swine plaf;ae and 

1 Htreptococci. 
S wineplagae, bac. i Swine nlairuo 


,, .do 




. . . do .......... 


Swine pla£n>« • 
Negative 

...do 


Negative 

...do 


ooli, cnroDiogene. 


r- r» 







It will be observed that these five animals died of swine plague pare 
and simple. Hogcholera bacilli were absent An examination of the 
pathological notes shows in every case extensive pneamonia, accom- 
panied by exudative pleuritis and terminating in some cases in necrosis 
of lung tissue. Perhaps the most instructive feature of the disease 
is the inflammation of the stomach and large intestine, which was 
especially marked in the second case. In the third, besides the intense 
hyperaemia, there was evidence of exudation. 

That such intense hyperaemia, provided the bacteria continue to act 
on the membrane, or provided they are of the proper degree of viru- 
lence, may lead to croupous and diphtheritic deposits and subsequent 
ulceration, needs no comment. Moreover, the swelling of the solitary 
follicles with discharge of contents, as observed in No. 5, may lead to 
subsequent ulceration. It is interesting to note that the disease reached 
its severest expression in No. 2, both as regards lungs and intestines, 
and in later cases the lesions became less extensive. 

The table giving the results of the bacteriological work shows a grad- 
ual disappearance of the swine-plague bacteria and the invasion of other 
bacteria. Thus, in the spleens of Nos. 1, 2, and 3, swine-plague bacteria 
were detected while the cultures from the spleens of Nos. 4 and 5 re- 
mained sterile. That these bacteria perish very speedily in the body 
is highly probable when we bear in mind that they die very rapidly in 
culture media, a fact to be pointed out further on. 

The swine-plague bacteria causing this outbreak were not so virulent 
as those of the preceding one as demonstrated by the inoculation of 
rabbits from lung tissue and pure cultures. While those of the pre- 
ceding outbreak destroyed rabbits in 20 hours, these were fatal in firom 
2 to 13 days, according to the size and age of the rabbit. The following 
inoculation, made about 4 weeks after the last case was examined, serves 
as an additional illustration : 

December 6, 1889. — A large white rabbit inocnlated subcataneonsly on right ear 
with a loop rubbed over the growth of an agar caltnre. The animal was fonnd dead 
December 10. From the place of inoculation on the right ear, sappnrfttion had ex- 
tended down over the muscles of the neck. In right pleural sac, on plenra of ribs 
and right lung, a thick creamy deposit. A similar, more consistent exudate on epi- 
cardium, which is more or less ecchymosed. Other organs not affected* 



^ 65 

r After coDstant cnltivatiou of this germ for a year and a balf on agar, 
it had lost its virulence to a large exteut, so that auhcutaueous inocu- 
latiou produced merely a local abacess. While small dosea injected into 
the circulation failed to killarabbit larger doses were still rapidly fatah 

March 31, 1891. — A rabbit reoeivea under the skin of abiloraen 0.2 ciibio cectimetTe 
of n bouillon culture iirepared from an agar cQlture one day old. The rabbit Bnb- 
sequently aeemed aligiitly ill, but recovoroii. It was chloroformed on the thirteenth 
day. Over an area several incliea aqiiare the Bnbcutia is thickened by punileDt iu- 
liltr»tion, and the skiu gangrenous and very dry aud hard. The abdomical mueclea 
slightly ecchymoaed. Intemal organs not affected. 

April 13. — Large white rabbit receives into ear vein 0.3 cubic centimetre of a, bouil- 
lon culture 24 hotirs old. The rabbit showed sigua of slight illnesa for a time. It 
began to grow thin, and after several weeks it was noticed to loove with great diffl- 
culty. Chloroformed ou the nineteenth day. Very anaemic and tbiu. luternal 
orgauB pale but normal, excepting kidneys, of which cortex is fatty. Several ab- 
scesses nnder the fascia of tbe left knee joint, containiug a bluish niitky pus. Gland 
in right axilla converted into an abscess. 

April ay. — From an agar culture 4 days old a turbid suspension of the coinlenaation 
water was injected into an ear vein of two rabbits; one rectivod one-fourth eobio 
centimetre, tbe other oue-half cubic centimetre. 

Both very quiet and drowsy on the following day; breathing accelerated; one 
with head drawn backward. 

May 1.— 'Both dead thia rHorning. In the Urst animal tbe bead partially drawn 
backwards on neck. Spleen dark, large, and softened. No peritonitis. Liver Tery 
pale; on left lobes much interlobular pale yellowish mottling. Clondy BweHiug of 
cortex of kidneys. Fatty degeueratLou of heart muscle. Right heart distended 
with dark, partly coagulated blood ; In left, a smal! quantity. Both lungs cedemo- 
tons; right hypoBtatic. In Kpleon aud blood a moderate number of bacteria abowiug 
polar atain very clearly. Cultures from spleen aud blood contain only the injected 
bacteria. 

In the second rabbit same position of head. Peritonitis indicated by a viscid exu- 
date on ccecum and stretching between coils of iutcbtine when these are' separated. 
On liver aud spleen a pseudo-membrane. The exudate oonsiats of endothelium in 
state of fatty degeueration, strands of fibrin, leucocytes and large numbers of bac- 
teria showing polar staiu. Spleen, liver, kidnoya, aud blood contain no bacteria 
viaibto in cover-glass preparatioue. Livor and kidneys hypersmic. Heart in dias- 
tole. Both sides contain dark, partly coagulated blood; heart muscle fatty- 
Lungs, especially ventral portions, congested. Cultures the same aa in preceding 

While there existed the difference in pathogenic power between the 
bacteria of this and the preceding outbreak, none could be detected 
from a biological and morphological standpoint. 

The question naturally arises, why should such attenuated bacteria 
as these produce such a severe disease f The age of the infected ani- 
mals probably will answer this question. Observers have not infre- 
quently noted the fact tliat bacteria sufliciently attenuated to be harm- 
less to old animals prove fatal to the young. The Pasteur school has 
made nse of this observation in increasing the virulence of pathogenic 
bacteria by first passing tliem through young animals. Jt is claimed 
that after a number of inoculations these bacteria become fatal to older 
animals as well. 



56 

Having thus demonstrated an outbreak of pure swine plague among 
the animals in pen 3, let us turn briefly to the diseased swine in the 
other pens which came under observation. It will be remembered that 
one pig from pen 5 died November 10, and was taken to the Experiment 
Station, where it was kept in the refrigerator until November 11. The 
subject is sufficiently important to warrant the reproduction of the notes : 

No. 6. Stomach contracted ; contains a smaU quantity of food. One ulcer at the mar- 
gin of the cesophageal expansion, the latter covered with a thin brownish-yellow layer 
of desquamated epithelium. In the ileum small ulcors, about 2 to a square inch, one- 
eighth inch across; adherent slough stained yellow. Extensive ulceration in csecnm 
and upper colon. The ulcers vary from one-eighth to one-half inch in diameter, black- 
ish on the surface. The base consists of a firm yellowish-white tissue extending into 
muscular coat. Six inches below the valve one large, button-shaped ulcer, the firm 
base extending to serosa and three-eighth inch think. The serosa under it discolored 
and the meso-colon adherent to it. In the lower colon are a large number of circalar 
pale spots on the discolored, pigmented mucosa, representing probably the places to 
which exudates had been attached but now shed. 

Lymph glands in lesser omentum and meso-caecum with cortex hemorrhagic. 

In left pleural cavity large patches of blood extravasation under pleura of ribs. 
No pleuritis. Posterior mediastinal and bronchial glands hemorrhagic. Throughout 
the entire lung tissue are disseminated hepatized foci of various sizes surrounded by 
healthy and more or less emphysematous tissue. Thus in the right lung about one- 
half of both cephalic and ventral lobes and a small volume of principal lobe involved. 
In the left lung one-half of cephalic lobe and tip of ventral lobe hepatized ; in the 
principal lobe six small foci. One-half of median lobe hepatized. The small air 
tubes plugged with thick mu co-pus. In the principal lobe several of the foci directly 
traceable to plugs of lung worms, which are very abundant. 

Spleen somewhat enlarged, discolored ; pulp soft. 

Bacteriological examination : In spleen pulp a considerable number of hog-cholera 
bacteria detected. An agar and a bouillon tube inoculated with platinum wire. In 
the former a considerable number of isolated colonies of the same size appear, which 
are, so far as examined, hog-cholera bacilli. In the bouillon tube only hog-cholera 
bacilli observed. A rabbit inoculated with a particle of spleen pulp died in 4 days. 
At the point of inoculation a small abscess. Spleen large, dark, softened ; contains a 
a few hog-cholera bacilli. Numerous very small points of necrosis on liver surfaces. 
In an agar culture from the spleen only hog-cholera bacilli detected. 

With a particle of lung tissue in which a few hog-cholera bacilli were observed a 
gelatine roll A and an agar plate B prepared. In the roll there were present at end 
of a week a large number of small brownish colonies and about fifty several times 
larger. By carefully removing the smaller ones to bouillon these were found to be 
hog-cholera bacilli. The large colonies not examined. On the agar plate a consider- 
able number of vigorous hog-cholera colonies appeared in 2 days. 

Case 7. November 13. Large white female, 5 months old, weight 65 pounds. Ven- 
tral aspect of body and ears bluish red. Subcutaneous fat abundant. Lymphatic 
glands of groin with surface purplish and parenchyma mottled red and gray. A 
small number of ecchyraoses on abdominal side of diaphragm. Spleen very large, 
blackish, soft. 

Stomach partly filled with food. Mucosa of fundus, and, in fact, of fully one-third 
the whole area of stomach surface, intensely reddened. The hyperaBmia extends to 
submucous tissue. Slight ecchymosis and pigmentation of duodenum. Occasional 
petechias in ileum ; Peyer^s patch near valve pigmented. Entire mucosa of cfecnm 
and colon purplish gray and dotted with petechias. On mucosa of c£ecnm about 30 
pale circular spots slightly depressed, which evidently were the seat of adherent 
sloughs or exudates. In rectum petechisB ; glands of meso-colon hemorrhagic. 



In tLe principal loTie of left luug a, brigbt red hepntizi^d mass aliout tliree-qanrtera 
of an iccli in iliameter; in the rigbt corrDspoudin^ lolio a UAsa lialf us large. Ja 
the bronchi of those lobes very many Inng worms and a ccinsidtrable quantity of red- 
dish, jrelatinons mnons. No other hepatii^ation and no pSeniitie observed. On the 
Burrnee of the Innga a few peteeliia". TLe location of the hepatizationa raakes it 
probable tliat luug worms wore the original oanse. 

Liver shows niatlfod pnat-mortem chauges. Kidneys with cortical portion dolled 
with uumerons heraorrhngio point*. Clota of blood anrronnding papilla. 

In the spleen were observed hog cholera nni) large baoilU. la an agar oulbnra with 
wire nn memos hog cholera colonies appeared. 

It is a remarkable tiict that tbere sliould be two diseaaes of different 
nature in adjoiniug pens at about the same time. It is not improbable 
that Log cholera was brought with the ten pigs, but in this' case it is 
quite curious that those in pen 1 were not attacked. We must 
8ume that perhaps but one pig was chronically iufected (old ulcers) and 
that this pig placed in pen 5 formed the starting poiut of a slowly de- 
veloping infection among the others. 

IX. 

In July, 18!)0, the attention of the Bureau was called to an ontbreak of 
swine disease of a very fatal character about 2 miles northwest of Pleaa- 
antville, New Jersey. Veterinarian F. L. Kil borne visited this locality 
July 21 and obtained the following information from Mr. Joseph Youi 
the owner of the diseased herd, who gave us all the facilities in hia 
command for the investigation of this plague. 

On May 9, 1890, Mr. Young bought forty-flve piga, 2J to 3 months old, 
collected by a dealer from several countiea. May 23, a second herd of 
flfty-two pigs was obtained from the same source. In this lot were 
noticed several unthrifty animals, and coughing was beard up to the 
time of the appearance of the diaease. About July 1 they began to die, 
one of the unthrifty ones being the first to suecnmb. Deaths, at first 
few in number, increased until the number reached from three to eight 
per day- Thus from July 1 to July 19 thirty-four perished. On July 
20 four died, on July 21 seven died, on July 22 eight died. 

No swine had been on this farm for several years except four animals, 
which had been raised and fattened last season and which bad always 
been in good health. 

The herd was watered from a well, tlie waste being permitted to 
run into a little depression or wallow in a dry sandy soil. The food 
consisted of slops, brought over from Atlantic Oity in boats. Several 
other herds in the neighborhood were being fed in the same way with- 
out any untoward results at the time. It should be stated, however, 
that later several other herds in the neighborhood became iufected. 
This information did not reach us until after the disease had died out. 

Tlie symptoms noted by the observant owner were coughing, loss of 
appetite, and occasional vomiting. The animals strayed into bushes 
and other hiding places, soon became lean and gaunt and weak \\i Vafe 



* 



58 

hind quarters. They died 3 to 5 days after showing signs of disease. 
Some lived longer, others died quite suddenly. 

Of the forty-two pigs remaining July 23, twenty died between July 
23 and July 28, five died on the Experiment Station, and only seven, out 
of a total of ninety-seven, lived through the disease. 

Seventeen animals came under our observation. Of these, twelve 
were examined on the farm and the remaining five sent alive by express 
to the Experiment Station. Here they all died within a week after then* 
arrival. Of those examined on the farm, Nos. 1 to 4, inclasive, and 
Kos. 11 and 12, came under Dr. Kilborne's observation. From Nos. 5 
to 10, inclusive, cultures were made on the farm by the writer. Cul- 
tures were therefore made from eleven cases only. 

The bacteriological examination of Nos. 5 to 10, inclusive, can not be 
regarded as thorough, owing to the innumerable insect pests on the 
farm. Much work, however, was bestowed upon Nos. 13 to 17, inclu- 
sive, which died at the Station. The notes of this outbreak are reported 
in detail, while the usual summary will be given farther on. 

No. 1. July 21, 1890. Weight of animal about 50 pounds. Skin not reddened. A 
few delicate fibrils of exudate stretching over coils of intestines. Spleen very much 
enlarged, congested. 

Digestive tract. Stomach contains a small quantity of food. Mucosa of fundus 
intensely hyperaemic, bordering on hemorrhage. 

Small intesUne nearly normal. Contents of large intestine liquid. The mucosa 
of caecum and entire colon nearly concealed by a layer of dirty, greenish-yellow, diph- 
theritic membrane, quite readily scraped away, exposing a deeply reddened, raw 
surface. 

Kight lung normal. The entire left Inug is covered with a pale yeUowish (friable) 
exudate, which glues this lung to surrounding parts. The lun^: itself contains 
masses of hepatized tissue, aggregating, perhaps, one-fonrth of the entire lung. 

The lymphatic glands generally are enlarged ; the cortex, and sometimes medul- 
lary portion also, infiltrated with blood. Other viscera not markedly changed. 

No. 2. July 21, 1890. Weight of animal about 75 pounds. Died very suddenly 
during the day. No skin lesions. Spleen barely larger than normal. 

Digestive tract. Only the large intestine was markedly affected. The mucosa 
extensively pigmented with occasional patches of hyperaemia. In colon just below 
the valve one ulcer one-half inch across and a few smaller ones discovered. 

Each pleural sac contained nearly 500 cubic centimetres of slightly-clouded serum 
containing large masses of gelatinous coagula. The lungs free from pneumonia. 

Lymphatic glands and remaining viscera not diseased. 

No. 3. July 22. Weighs about 40 pounds ; died during the night. Had been sick 
at least a week according to statement of owner. Spleen moderately gorged with 
blood. 

Digestive tract. The mucosa of caecum and upper half of colon more or less pig- 
mented and beeet with rather deep ulcers from one-eighth to one-third inch in 
diameter. 

Fully three-fourths of the right lung is hepatized and contains a few necrotic 
caseous masses. The pleura of this lung covered with considerable pale yellowish 
exudate and adherent to pericardium. Left lung and pleura normal. 

No. 4. July 22. Animal died quite unexpectedly last night. Slight exndfttive 
peritonitis. Spleen engorged. 

Digestive tract. Stomach normal, filled with food. Mucosa of large intestine 
extensively pigmented, merging into hyperadmia in the lower colon. NomerouB 




69 

elevfttfld bntton-like olccrs ono-fourth to thrnofoartlis incli in diameter, f 
from CiBCDin to lower colon. 

In both loDgs a small nnmber of poeumanic foci, apparently of an aonte character. 
Slight qnantitf of plenritic exndat-e in tlio right pleural Hae. 

Lymphatic glands in general with cortex eugni'geil with hlood. Petechia? in tlia 
cortex of kidneys, beneath peritoneal covering of iliaphragm, stomach, and walls of 
ftlidomon. 

No. 5. Jnl;22. Pig died between 10 a. m. and 6 p. m.; esarained at 7 p. ra. Snper- 
Dcial lymphatic glands of the groin hyperiemjc tbroughoiit; cortex haa a purplish 
color. In the digestive tract the mucosa of the fumloB ot the stomach involved in 
hemorrhagic inflammation with saperficial necrosis. In the cieenm and upper colon 
the rancosa is anperBciallj" necrosed. 

In both p'.enral sacs a considerable amount of pale yellow serum. The iutetlobu- 
lar tissne of the longs distended with it. No hepatiiation. Fatty (lege Deration of 
the corMx of kidneys. 

This was the first animal ftoin whicli cultures were attempted. A tnbe of gela- 
tine was inoculated with a bit of spleen tissne. Subsequently liquefaction took place. 
The tnrbid liqnofied maaa covered by a viscid pellicle. The small baeillas canalng 
this liquefaction grew in the same manner iu bouillon. It formed a viscid Bnrface 
membrane very speedily, leaving tlie liquid clear. 

An agar tnbe which was inoculaled with a bit of spleen tisane remained sterile. 
Similarly two agar tubes inoculated with a loop of serum from both pleural cavities 
failed to develop. A pipette of pleural effusion collected at the autopsy and sealed 
was examined subsequently at the laboratory. It contained a large spore-bearing 
bacillna and some short rods in chains. In order to detect the presence of any swino' 
plague germs in the serum, a bouillon cnltnre was also made from the serum, iu which 
of course the several germs developed together. A rabbit inoculated in the oar with 
a drop of this culture remained well. Nei ther e wine-plague nor hog-cholura bacteria 
were thus obtained from this animal. 

No. 6. Pig killed in what appears to be a dying condition. Ho lesiona found in 
lungs or digestive tract. Spleen somewhat enlarged bat firm, not congested. 

From The spleen of this animal a minute bit was placed in tnbe of gelatine and 
of agar. Both remained porm.inently free from growth. 

From the liver two similar cultures were made. In the gelatine tube a fungns had 
develoned after a week, but no bacteria. In the agar tube large spore-bearing bacilli 
appeared in the condensation water. 

Neither swine-plagne nor bog-cholera bacilli were obtained from this case. 

No. 7. Whitepig, died in oourseoftlieday. Examined with Nos. 5 and 6. Ecohymoses 
on addnctor muscles of the thigh. Hemorrhagic condition of cortex of lymphatic 
£lands. Petechial under serosa of small and large intestines. Hemorrhagic inflamma- 
tion ot serous covering of nreters and bladder. Cortex of kidneys enlarged, pale, fatty. 
Lungs and digestive tract not affected. 

A bit of spleen placed in a tube of gelatine and a tnbe of agar failed to give else 
to any growth in these tubes subsequently. 

Iu an agar tube inoculated with a bit of liver tissue, a large s pore-bear iug bacillus 
was found which grew only in the condensation water and not on the surface. 

No. 6. Pig killed in a dying condition. Affected with umbilical hernia. The 
mucosa of the large intestine was deeply pigmented, both lungs extensively hepa- 
tined. Spleen moderately enlarged A gelatine and an agar tube inoculated with 
bits of spleen tissue, both negative. 

No, fl. Died in course of the day ; examined between 7 and 8 p. m. Spleen large, 

gorged with blood. Pneumonia in localized regions throughout both lungs. Lnng- 

worma present. The mucosa of the large intestine of a dark blnish color with seat- 

tering ^itish spots of slight exndation. From this caae only an agar tube was 

^^^aenlatad with a particle of spleen tissue. On July 24, two d^a later, there had. 



60 

appeared on the inclined sarface of the a<rar abont thirty isolated colonieSy oironlari 
slightly convex, l^ millimetres in diametor, grayish, transiacent. The clear oouden- 
sation water contained a flocculent deposit. Colonies and condensation water show 
minute oval cocci apparently identical with swine-plague bacteria. 

From these colonies a peptone bouillon tnbe, an agar tube, and a gelatine tube were 
inoculated August 25. On the following day tbe liquid culture contained minate 
clnmps adhering to sides of tube. Liqnid nearly clear. The agar tnbe showed a 
delicate grayish line on the surface. Both tubes contained only the minate oval 
cocci. The gelatine tube remained /ree/roni^rou;^^. To test the pathogenic nature 
of the germ a rabbit was inoculated in the ear from a colony of the original spleen 
culture July 28. (This sabbit had been inocnlated June 3 into the thigh with a 
very attenuated culture of swine-plague bacteria sent to the laboratory.) The rab* 
bit died in 2^ days. From the original inoculation an abscess as large as a hen's egg 
had formed on the superficial muscular layer of the thigh. Spleen maoh enlarged, 
soft. In stained cover-glass preparations of spleen, liver, and blood numerons swine- 
plague bacteria were detected. A tube of agar was inoculated from the blood and a 
tube of bouillon from the spleen. On the following day a uniform grayish glistening 
layer had appeared on the agar surface, made up, so far as the microscopic exami- 
nation could go, of non-motile oval cocci. The bouillon culture, nniformly clouded, 
contained the same bacteria only. These were readily identified as swine-plague bac- 
teria. 

No. 10. This animal died during the night ; examined at 7 a. m. next morning, 
July 23. Subcutaneous lymphatic glands in the groin very large, in part hemor- 
rhagic. Spleen enlarged, firm, not congested. In the digestive tract the mucosa of 
csBCum is concealed by a very thin necrotic layer ; mucosa itself purplish. This con- 
gestion extends along entire colon ; meso-colic lymphatics hemorrhagic. 

In thorax, the base of all lobes of both lungs involved in bright red hepatization. 
Pleural sacs contain considerable serum which distends also the interlobular tissue. 
Heart muscle quite pale and discolored in patches. 

A small number of tube cultures in agar and gelatine were prepared at the autopsy 
as follows : 

An agar tnbe inoculated with a bit of spleen tissue showed no growth on the fol- 
lowing day. Condensation water turbid, however, containing a large spore-bearing 
bacillus, the bacillus becoming spindle-shaped or nearly spherical when the spore 
fully matured. No other bacteria detected. On the second day a faint growth had 
extended on the agar surface, and a small motile bacillus detected. Agar plates ware 
then made to isolate this bacillus, which was quite easily accomplished since the large 
spore-bearing bacillus failed to grow on plates. The small bacillus formed grayish, 
slightly gelatinous surface colonies. It was actively motile, the motion being chiefly 
a twirl with little change of place. Careful subsequent tests showed it to be entirely 
different from the hog-cholera bacillus with which it might have been confounded. 

From the kidney two minute bits of tissue were transferred, onetp a tnbe of agar, 
the other to gelatine. The agar tube contained on the following day about fifty col« 
onies of the same germ found in the spleen culture of No. 9, i. e,, swine plague. In 
the condensation water the large spore-bearing bacillus was also present, and a few 
gas bubbles in the agar. The gelatine tube showed very slight liquefaction of the 
gelatine on the surface where the bit of kidney tissue lay. This was probably due 
to the large bacillus which did not develop any more in this situation. 

From the liver an agar and a gelatine tube culture were prepared in the same 
manner. 

In the agar tube a considerable number of colonies of the swine- plague bacteria 
had appeared July 25. No other germs subsequently detected. In the gelatine cul- 
ture slight liquefaction took place, owing to the presence of an actively motile bacillus 
in chains. 

An agar tube inoculated from the pleural effusion remained sterile. 



With the avrine.plague bacteria frotn the liver a rabbit was iaoonlated in the ear 
by priukiDg the skiu with iaacut anil iaaerting a platiaani wire dipped iuto a culouy 
oil agar. Rabbit dead next niaruiiig. Inocnlation woaud ou ear bliiisli and all veins 
disteuded. Similarly veins of aiibcntis fillud witb blood. Silicon enlarged, oon- 
{■eated. Lirer in large patt iuvadod by ooocidia. lu the bloud and Bpleen unmeroas 
bacteria delected ahowing the polar ittaio. An agar and a bouillon enltiire from the 
blood and Bpleon oontain aubHoquuntly only thii same germa fonnd in the tiaaues. 
Bonillon faintly ulnuded, no clumpa preaent. Agar growth like that from case 9. 

Rectiona ftom the lung tiaane of caae ID hardened in alcohol were ataiacd iu alka- 
line methylene bine andalnm onrmine. The interlobular tissue waa greatly diatanded, 
coutainiug a network of fibrin and very few cella. The alveoli contained a slight 
amount of fibrin and very few cella. Throughout the apecimens were individnol fila- 
ments and bandies of filamenta of a ratber large bacillus, evidently tbe same aa that 
obtained in one culture. Occasionally in the contents of the alveoli were seen ticat- 
tered bacteria of the size and form of awiue-plague bacteria. 

Sections from a Rubcntaneona inguinal gland hardened in alcuhnl and stained in 
alkaline niethylouo blue revealed large areaa infiltrated with blood corpnaclea and 
penetrated by dlatended blood vessela. In addition to tbe large bacilli found in the 
lung tiasae elumps of very small oval bacteria, identical iu appearance with awine- 
plagne bacteria, were found acattored over the entire section, the clnmps being largeat 
in the hemorrhagic area. 

In aectiooa from tbe spleen none but the largo bacilli were detected. The apleen 
waa extensively loaded with bluod pigment. 

The two following caaes were examined by Dr. KUbornu on the farm on the morn- 
tug of Jnly 3S. Both bad auccunibed during the nigbt. No bacteriological examina- 
tion was made, but the notes are given to show tbe extreme variation in the lesions 
of this outbreak. 

No. 11. Subcutaneous ingninal glands very large, hemorrhagic on section. Spleen 
very large, dark, friable. Mucosa of fundua of stomach very hyperiumic. Numerous 
petechiie in mncusa of small intestine. Mucosa of large intestine intensely con- 
gested, portions almost bemorrbagic ; depressed ulcers on Peyet'a patch near valve, 
covered with a thin alongh \ one ia over one-half inch in diameter. In the upper colon 
are large branny patebaa of superftoial necrosis, besides numerous smaller, ronnd 
points of necrosis. Tbe variona abdominal lymph glands with very hypersemio 
cortex. 

Ill thorax both pleural aaca contain 100 cubic centimetres of clouded Koruin. The 
costal and putmonary pleura covered with a yellowish, friable, meuibranoua exudate, 
oaiialng mutual adhesion of tbe various lubes. Pericardial soe not invaded. The 
major portion of both Innga hepatised, only the principal lobes being in part still 
pervioua.' Hepatized lobea dark red. Bronchial glanda bemorrhagio. 

No. a, reritonitis indicated by tbe preaence of 100 to liiO cubic eeutimeires of 
serous exndate in abdominal cavity. Some few fibrils of coagulated lymph atretched 
over intestines; estensive serous eft'naion between layers of meso-oolon, Sploen 
afi'ected like that of No. II, thongh loaa markedly so. 

Stomach contains about a litre of food ; mucosa pale and covered with abundant 
tenacious muGus. Slight eechymosia of upper duodenum. In lower duodenum and 
Home feet in length of jejunum the walls infiltrated witb extra vasotod blood to twice 
the normal thiuknesa. Huoosa of a deep red color and partly covereil by patches of 
&iable yellowish exndate readily removable. Considerable blood in lower small 
intestine with alight eoobymosiiof mucosa. 

Mucosa of large intestine more or leas pigmented. In eiecutn are three ulcers one- 
fonrtb to one-balf inch in diameter, the subjacent tissue being thickeued by iuBIlra- 
tion from one-half to three-fourths inch. On Peyer's patch near valve, and in upper 
and middle culuu, are about half a dozen aimilaT large depressed ulcers with very 
base, and some smallei; ones. 



^ftiakt 



J 



62 

Id tbe longs the cephalic and vcDtral lobes are iDvolred in pale red hepatization 
withont plenrisy. 

The abdominal and thoracic lymph glands more or leas hemorrhagic thionghout 
their substance. 

The followiug five sick animals were sent by express to the £xi)eri- 
ment Station of the Bureaa July 28. They reached the Station next 
day and were placed in a disinfected pen. 

No. 13 dies July 31, 3 p. m. ; placed in refrigerator until August 1. Weighs about 
30 pounds. Skin on ventral aspect of body more or less reddened ; over the ster- 
num a few excoriations. The enlarged inguinal glands show as lumps under the skin. 
On section they present a mottled gray and red surface, the red limited chiefly to 
the cortex. CEdema of the snbcntis over right knee. 

False membrane covers the left half of the mass of intestines and the spleen ; con- 
sists of an elastic, rather firm yellowish white layer. Spleen finnly glued to the 
surrounding intestines, Rlightly enlarged, dark, softened. Liver firm, cuts with con- 
siderable difficulty. Kidneys in condition of parenchymatous degeneration. One 
hemorrhagic spot in medullary portion of one kidney. Pelvis contains a whitish 
glairy liquid. 

Digestive tract. Two superficial necroses on the inner surface of lower lip in front, 
one on the upper lip and on edge of tongue near tip. Stomach contains a little 
deeply bile-stained fluid. Mucosa sprinkled with red spots of a washed-out appear- 
ance, most numerous in . fundus and near pyloric valve. Hypersemia of duodenum 
begins sharply at pyloric valve. From the opening of bile duct a few drops of thick 
bile can be exi)ressed. Remainder of small intestine not markedly changed. The 
Peyer's patch in lower ileum has some of its follicles enlarged from which caseous 
masses can be expressed. 

Large intestine contains much sand and gravel. Mucosa of caecum of a dark slate 
color. The summit of the folds of a purplish hue. Free edge of valve bordered by a 
thin slough. On Foyer's patch near valve areas of necrotic tissue of a yellowish color, 
resting on a firm, yellowish-white base three-sixteenths of an inch thick. 4Jpper 
colon has its mucosa of the same dark slate color, merging into a wine red. Two 
ulcers one-eighth of an inch in diameter observed. In lower colon congestion slight 
and gradually disappearing towards rectum. A small number of circular whitish 
erosions, apparently associated with the solitary follicles. 

Thorax. Of the left lung, the ventral and cephalic lobes are interspersed with 
small regions of collapse. The remainder of the lobes very emphysematous and hy- 
peru;mic. Of the right lung, the anterior half (i. e., including cephalic, ventral, and 
adjacent portion of principal lobe) hepatized, covered by a thin false membrane, 
gluing the various lobes lightly to each other and to chest wall. The diseased lobes 
show the regular mottling in the upper, dorsal portion. As we proceed towards the 
ventral portion the mottling is less distinct, the tissue firmer and interspersed with 
small, irregular* necrotic foci. The smaller bronchi contain a thick, whitish pus. In 
ventral lobe a portion of the parenchyma as large as a marble completely converted 
into a grayish-yellow homogeneous mass. Of the principal lobe about one-third or 
one-fourth hepatized. The mottling of surface very regular. On section grayish, 
circumscribed areas one-half inch in diameter interspersed. Over these masses the 
pleura is converted into a wrinkled, roughened, hide-like membrane. 

Trachea and bronchi contain small quantities of foamy liquid intermingled with 
yellowish particles. Bronchial glands barely enlarged, firm; some lobules pale, 
others reddened. - 

Bacteriological notes. At the autopsy an agar tube was Inoculated with a platinum 
loop lightly rubbed over the pleural exudate. On following day a thin grayish 
growth with condensation water clouded. Examination of hanging drop and stained 
coverglass preparations shows only swine-plague germs. 



^ 63 

In oover-glas8 preparutioDs of liepatized lung tissne » large Dumber of germH le- 
sembling swinB-pliigiie bacteria were seen, aUo some other lorms. Two agar plaWs 
Tvere made from the Itiuj; by thoronghly scoriihing the pleural surface, cnttiug out of 
tli« scorched area a bit of tissue and trauaferring with platinum loop the Hcrum coJIect- 
ing io this minute caTity to 10 cubic oentiiuetrea sterilized water. With oue loop of 
water ID cubic centimetres agar was inoculated for Plate A. From thin agar two 
loops were transferred to agar for Plate B. On following day about five colonies ap- 
peared on Plate A. These were made up of various bacteria. Plate B remained 
sterile. At tbe eame time a bouillon culture was made from the lung tissue. lu it 
several germs grew. These were plated. No swine-plague gernia obtained. 

With a bit of hepatized lung tissue, obtained as described above, a rabbit was in- 
oculated aubcutaneously Angust IS, 2 p. m. The rabb't was dead next morning at 
S a. m., i. e., in less than IS hanrs. In spleen, Uver, and blood pteparatio 
polar-stained swine-plague germs present. An agar culture from heart's blood ci 
tained only swine-plague germs. 

From tbe peritoneal exudate of pig, consisting of cells and fibrin and i 
bacteria of several varieties, two agar plate cultures were made. On Plate A one 
large oolouy of spore-bearing bacilli and one small colony of swine-plague germs. 
Plate li completely overgrown by the spore-bearing bacillus. 

A beuillon culture from tbe exudate cootaias streptococci and swine-plagne baato- 
ria. Agar plate cultnres were made therefrom and both germs isolated. 

At the same time a large rabbit was iuoculated subcutaueousty with a bit of the 
exudate. Dead within IS hours. Stained cover-glass preparations of blood ftom 
heart, spleen, and liver tissue show polar-stained swlue-plague germs. An agar cul- 
ture from tbe blood contains only swine-plague germs. 

From tbe spleen, after thoroughly scorching through the exudate, two agar plate 
cultures and a bouillon culture wore made with bits of aplccQ pulp. Tbe bouillon 
cultnre contained only swine-plague germs. On Plate A several hundred coloniea 
appeared next day. Tbe snperlicial ones from S to 3 millimetres in diameter withoir- 
colar, sharply outlined, slightly convex disk of a grayish glistening appearanoe. 
Those examined were made up of swine-plogue germs. Plate li remained free from 
growth. 

The swine-plague bacteria were thus obtained from lungs, pleura, spleen, and peri- 
toneal exudate, while hog-cholera bacilli, which were loolced for with the greatest 
care, conld not be found. 

Ko. 14. Died late Angnat 'i, and was kept in refrigerator until next morning. Be- 
fore death frennent, liijoid, yellowiab discharges were observed. 

On the left side, eitetidiug from steruum to the left forelimb, the snhoutis over the 
pectoral muscle is infiltrated with a gelatinous blood-staioed serum. The right pec- 
toral muscle somewhat discolored by extension of tbe process. A discolored, blood- 
stained area in tbe abdominal mnscle on the left side. 

Considerable post-mortem changes, in spite of tbe fact that the animal was kept 
on ice over uight. Spleen very large, dark, soft ; tbe tiaaue surrounding it stained 
with coloring matter of the blood. 

Mucosa of stomach in fundus very byperiemic, partly hemorrhagic. The oardiao 
expansion covered with a thin, blackish, removable layer. In llie largo intestine the 
lymphoid patch near valve is partly necrosed. About 6 iuches below valve a firm 
neoplastic button, about 1 iuch iu diameter and one-fourth inch thick. In oEecuin 
and parts of colon are numerous small (one -eighth inch) auperflclHl ucuruses. Mucosa 

Lungs considerably diseased. Of the right lung the ventral, adjacent portion of 
piinuipal, and small median lobe are hcpatized. On the left side both cephalic 
■Jid ventral are solidified. These diwnsed lobes are several times larger tbnn the 
normal collapsed lung, very firm and nodular to the touch. They are covered by 
«hreds and patches of exudate, gluiug tbe lobes firmly to each other, to the pericardiam 
and diaphragm. The nodular condition is doa to the preeenoe of ^iBx^'o.'a.ixitxsE lA 



i 



64 

firm, yellowish, caseous masses, varying from one-fourth to three-fourths inch in 
diameter, dispersed tliroiij>;h the hopatized tissue. 

Bact-eriological examination included the spleen, the lungs, and the pleural cavity. 
At the autopsy an agar tube was inoculated with a bit of pleural exudate. Smill 
colonies appeared on the agar surface on the following day, some made up of what 
appeared to be streptococci, others of micrococci. From this a bouillon culture was 
prepared, and the latter plated on the following day. From these paltes a coccus, 
growing in clumps and short chains, and a large bacillus, were isolated. At the same 
time a rabbit was inoculated in the ear from the agar culture. The rabbit died, in 11 
days. At the point of inoculation was a large ulcer. Spleen small. Cultures from 
various organs on agar and in bouillon remained sterile. 

With a bit of hepatized lung tissue a rabbit was inoculated in the ear. Dead in 8 
days. Ulcer at the point of inoculation. Right lung hepatiaed. Pleural cavity con- 
tains some blood-stained serum. Cultures from this animal likewise remain sterile. 

From a bit of lung tissue agar plates were also made. On plate A only two colo- 
nies appeared made up of large micrococci ; on plate B a thin grayish growth made 
up of spore- bearing bacilli. 

From the spleen two agar plates were made, from which a large coccus and haoiUiu 
fluoreacens were isolated. A bouillon culture made directly from the spleen was 
also plated with the result of finding a streptococcus and a large micrococcus. 

No. 15. Male pig, weight about 35 pounds. Died yesterday and at once placed in 
refrigerator until morning. 

On abdomen and inner aspect of thighs a few reddish scabs. Spleen somewhat en- 
larged and congested. 

Digestive tract : One ulcer on tip of tongue. Stomach contains a small quantity of 
muddy liquid. Cardiac expansion of (esophagus covered by a yellowish, easily re- 
movable layer of friable material. The mucosa dotted with small red pits. In fundus 
adeeply reddened area of small extent covered with a thin necrotic layer. Duodenum, 
commencing with pyloric valve, of a slate color and deeply pigmented in spots. Pig- 
mentation and aborescent injection extends down the small intestine. In large in- 
testine considerable pigmentation of mucosa. In csecum and upper 12 inches of colon 
are a large number of extensive ulcers of irregular outline, varying in length from 
one-half to several inches. They are slightly depressed and covered by ochre-yellow 
sloughs scraped away with difficulty. The entire depth of mucosa necrosed. Ileo- 
csBcal valve completely encircled by a band of necrosis. Below the first 12 inches of 
colon the necrosed areas are slightly raised above the surface. No marked thicken- 
ing or infiltration beneath them. In addition to the larger patches there are small; 
slightly depressed, round ulcers one-eighth to three- sixteenths inch in diameter, with 
adherent superficial slough. 

Of the lung tissue, a portion of the right ventral, an adjacent portion of principal 
lobe, and part of left ventral lobe collapsed, of a red flesh color ; no pneumonic infiltra- 
tion perceptible. In the bronchi and extending into branches are small quantities 
of translucent, very gelatinous mucus. In the collapsed right ventral lobe the small 
air tubes contain whitish cylindrical plugs of mucus and pus. 

Urine very turbid, contains much calcic oxalate but no albumen. Bacteriological 
examination was limited to the lungs, spleen, liver, and kidneys. 

From the collapsed lung tissue agar-plate cultures were made with a minute hit of 
tissue. Plate A on following day contained numerous isolated and one spreading 
colony; the latter made up of motile spore-bearing bacilli, the former of swine- 
plague bacteria. Plate B showed but two grayish flat colonies, composed of large 
cocci. 

A rabbit inoculated subcutaneously with a bit of lung tissue was found dead on 
the morning of the second day. At the point of inoculation more or less extravasa- 
tion of blood. About 25 cubic centimetres of blood-stained serum in abdominal cav- 
ity. Liver has a red clay color. Cultures on agar and bouillon from heart's blood 
and spleen contain only swine-plague bacteria. 




66 

wpreparalioQHof Bpleeii ptiJp from pi;j showed aome Inrge ( poet- mortem) 
bacilli. Oq an agar plato bntb awino-pUgue baut.iTia anil motiU- bacilli resembliiig 
bog cbiilura ware ieulatod. Tiieiie mottlo bacilli wore caiefully studied aad compared 
with hog-cholera bacilli. The reBolts are given farther an.* 

Frtiui the liver, in which a few large bacilli were ubaervud in oover-glasa pruparv- 
lloua, a boiiillou and au agar culture were prepared. In both there a])peared awine- 
plague bacteria acd streptouocci. These were iuolatcil aa u^i"' plates. A rabbit in- 
oconlated from the boaillon cnttnre by a prick in the ear was dead in leaa than SO 
bbara. On Bmall intestine nuiuerona ecchymosea. Spleen soniewhat enlarged ; lungs 
hyperseraic. From blood and Bpleen culturcB were made and cover-glass preparations 
examined. All showed ewine-plague germs and tlieae only. 

From the kidaey, which apparently contained no bacteria, an agar aud a bouilloD 
culture were made with minute bita of tissiie. The latter reinained sterile. The 
former allowed flaky masaea of micrococci reaembliug the swidB-plagiie germ but had 
no efi'ect ou a rabbit inoculated therewith. To teat virnlence of the awlne-plague 
bacteria isolated on agar plates from Inng and spleen, bouiKou cultures inoculated 
fi'om colonies on the plates were injected into two rabbits subcutaueously, each re- 
ceiving one- eighth cubic centimetre. Both were dead next day. In the oiganawere 
awiue<plagne germs in large unmbers. The same geruia obtained in culture from 
these rabbita. 

Gelatine roll cultures made from these bouillnn cultures failed as nana] to develop. 

No. 11). Female pig, weight from 7!i to HO lbs. Died at noon, August 4 ; examined 2 
hours later. Genei'al condition of body good. Ou ventral aurface along median 
line and on left fore-lliub, slightly elevated aoaba one-half inch in diameter. Ex- 
tensive Boroua infiltration of BuperAcial muscular tissue of ventral aapeot of neck 
and sternum and of muscles under scapula, estendiug along the muscles of the loft 
limb as far as the toea. The limb is very much swollou, the skin bluish red. Sub- 
ciitaneuus lymph glands of groin enlarged, dnu, aud pale, mottled with red lines aud 
streaks- 
Spleen enlarged, dark, and aoft. The fat of the meaentery dotted with petaebis. 

Digestive tract : One ulcer on loft margin of tongue. The fundus of stomach has 
Ita macosa thrown rntoamallfoldsanddeeply reddened over an area of about 8 inches 
in diameter, the hyperiemia being moat intense on the periphery of thia area. About 
3 inches irom the pyloric valve an area of necroaed tissue 3 inuhes long and 1 inch 
wide, tlie slough blackish, iuvolviog the entire mucous layer and one-eighth to one- 
fourth inch thiok. Lymphatic glands ou leaser cnivature with homorrhagic cortex. 

Mucosa of dnodeuum deeply pigmented, the pigmentation beginning abruptly at 
the valve and extending with variable intensity throughout the entice small intestine. 
Mesenteric glanda with cortex much reddened. 

Contents of large intestine of au earthy character, more or less adherent to the 
uincous membrane. Mucosa of uii^cum aud colon of a pale elate color. In the rectum 
u considerable number of somewhat faded pniiotifnnn extravasations on a pale mu- 
cosa. In casoum, 2 inches from valve, one ulcer, one-half inch in diameter, .with super- 
ficial, pultaceous slough. On Puyur's patch near valve one small nicer. In the upper 
colon about 3 iiichett &om valve, an irregular patch of neorosed mucosa, about 2 
inches long, with blitckiah surface and rather lirm, yellowish base one-eighth to one- 
fourth inch thick. In remainder of colon three superficial healing ulcers with eaaily 
detachable slough. 

Liver eniargud : interlobular marking appears broadened and pale, the center uf 
acini dark red. Parenchyma somewhat softened and hyperiemle. No sensation of 
grittin ess imparted to knife. Much fat observed in sections of fresh tissue in the 
form of large globnlea. Cells sharply outlined, nucleus distinct. 

Kidneys show nnder capsule a small number of petechia, Organ very pale througli- 
ont, espeoiaUy cortex. 



66 

Oyer both langs the interlobalar tissue is distended with deftr, yellowish sernni, 
some in pleural sacs. PareDchym» (edematous, not hepatized, with exception of a 
necrotic and cBdematons focus near tip of right priucipal lobe adjacent to large bron- 
chnsi which at this point is occluded with adult lung worms. Trachea and bronchi 
contain much foam and yellowish flakes, fironchial glands enlarged ; some lobules 
with cortex hemorrhagic, others mottled red and pale. 

Heart cavities and valves normal. Left auricle sprinkled thickly with panctiform 

hemorrhages. 

Bacteriological examination : Two agar tubes inoculated with a loop of pleural 
serum remained permanently clear. 

Agar plates from the (edematous lung developed on plate A about 150 ooIodIos of 
hiioillu8 fluoreacena. On plate B one similar colony. A rabbit inoculated with a bit of 
the same material remained unaffected. 

Spleen pulp shows no bacteria on micro8(}opic examination. One agar plate pre- 
pared with a bit of spleen pulp shows growth only around the bit of tisane. The 
growth made up of motile bacilli which resemble hog-cholera bacilli. The notes of 
the comparative studies of these bacilli are reserved for the end of this chapter.* 

A tube of bouillon inoculated from the spleen remained clear. 

Liver tissue shows no bacteria on microscopic examination. Two agar plates pre- 
pared with a bit of tissue remain sterile. A tube of bouillon inoculated in the same 
manner became clouded with a short, thick, non-motile bacillus. Agat plates from 
one kidney likewise negative. 

Pig No. 17 died August 5, in the morning, and was examined soon after. Female, 
weighing about 40 pounds, and in good (condition. 

The subcutaneous lymx>h glands in the groin are enlarged and reddened, in part 
hemorrhagic. In peritoneal cavity, a considerable quantity of straw-(}olored serum. 
The serosa of large intestine roughened and covered by shreds of exudate. A con- 
siderable mass of gelatinous exudate between layers of mesocolon. Meso(solic 
glands swollen, very hypersdmic. Spleen very large, dark colored, friable (11 by 3 
by f inch). 

Digestive tract : Stomach partly filled with a thick pea-soup like liquid. Fundus 
over an area of 4 inches in diameter, deeply (congested and swollen. A few asoar- 
ides in stomach. The mucosa of ileum sprinkled with numerous punotiform hemor- 
rhages. The ciecum appears as an enormously enlarged, dark, bluish-gray body, the 
color being due to diffuse blood extravasations. To it are adherent several coils of 
small intestine and of colon. It is impossible to separate these parts, the adhesion 
being due to extensive inflammatory deposits. The wall of csBcum shows great 
thickening; in several places it is 1^ inches thick. The mucosa of c»cum and 
upper colon sprinkled with large numbers of ochre-yellow excrescences about one- 
fourth inch apart, and from one-eighth to one-half inch in diameter. These are read- 
ily pulled away from the membrane, some leaving but a faint depression, others a 
roughened spot behind, surrounded by a bluish-red zone. The larger the excres- 
cences the deeper the necrosis beneath them. The mucosa is in general of a dirty 
slate color, faintest in the rectum. 

Lungs normal with following exceptions: An area of collapse 1 inch square in right 
cephalic lobe, and a small area on diaphragmatic surface of right principal lobe about 
one-half inch square showing consolidation beneath. Bronchial glands and those at 
base of heart with cortex hemorrhagic. Air tubes free from mucus and lung worms. 

A considerable quantity of serum in heart-sac. Epicardinm is covered with a very 
delicate exudate and is thickened and roughened. Ecchymoses on left auricle and en- 
docardium of left ventricle. 

Liver not markedly changed ; bile very thick and flaky. Parenchymatous degenera- 
tion of cortex of kidneys. Some petechisB on pyramids and in pelvis. 

Bacteriological examination: From the pericardial exudate one f^gar and one 

"""""^^^ ~ • — ■ *■ ■■ ■ XJ ■■■■ L ■■ ■ 

* See page 77. 



boDillou tnbe inocnlated with platiDum loop. Buth leinaioed sterile. Similarly 
two (obeH inooalated with peritoneal exudate remained Bt«rile. Agar plale cultiiroH 
from the spleen which ahowed no germs on mioroBuopiu esamitiatioa were niadu by 
addin); to tnbe A a bit of spleen pnlp, to B three loops from first tube. Plat« A de- 
veloped one colony made np of mioiococci. On plate B one colony mode np of bacilli 
appeared. A liuuillou culture made at the same time with bit of spleen pulp became 
clciadod and contained a large spore-bearing liacilliiB and a miorococous. This was 
plated, but only one colony developed made np of cocci. A rabbit inoculated at same 
time from bonilton remained un.llfected. From the liver agar plates remaiped sterile. 

The important pathological cbanges found in these 17 cases varied 
greatly from animal to auimal. lu some eases tbe lungs were most 
severely involved, iu others the K'sions in the large intestine must be 
regarded as most important. Id this respect this outbreak differs very 
decidedly from the two preceding ones, in which there was more or less 
uniformity observable. Besides therespiratory and digestive tracts, tbe 
lymphatic glands and the serous membranes were most frequently in- 
volved. In the glands tumefaction with hyperemia and hemorrhage was 
quit^ common. In the lungs the axtpearance of tbe hepatized regions 
varied considerably. In some necrotic changes had already appeared. 
Tbe following synopsis of the lesions will serve to illustrate the state- 
ments made: 

No. 1. Jnly 21, It!90. FuenuiODJaof left lung with exudative plenritls. Hyperieniia 
of Htomaoh ; dipbtheritio inUamniation of large intestine. Lymphatic glands hyper- 
amic and hemorrhagic, Spleei> very large. 

No. 3. Double Herons plearitis. Large iuteBtine hypemmlc and pigmented. Sev- 
eral ulcers. 

No. 3. PneUDioniaof rigbtlung withnectoticmaasea; pleuritis, pericarditifL Ulcer- 
ation of upper large inteatine. 

No. 4. Paeumonic foci in both lungs; pteuritis. Ilypemmia, pigmeutation, and 
ulceration of large inteBtino. More or letia blood axttavasatiou in lymphatics. 

No. 5. July 22. Double serous plenri lis with interlobular (sdema of lungs. No 
bapatization. Hemorrhagic itifluniuiuticm of stomut^li ; similar infiauusatiou of large 
intestine with superficial necrosis of mucosa. 

No. 6. Killed; examination negative. 

Mo, 7. Hemorrhagic lynipbatica; subserous hemorrhages in abdomen. Lungs and 
digegtise tract not affected. 

No. H. Exteueive hupatixatiou of lH)th InugH ; pigmuntation of large intestine. 
■ No. 9. Spleen largo. Scattering pnunmouic foci ; longworms. Hypersmiaof large 
Plutestine. 

Nu. 10, Partial hepatization of lun^ with interlohalarcedema and serous plenritis. 
Lymphatics hemorrhagic. Hypersniia and superiicial necrosis in large intestine. 

No. 11. Jiily2H. Extensive hepatization of lungs with double plastic pleuritis. 
Hyperemia of stomiicb. Diphtheritic inflammation of largo intestine. Lytupb glands 
hvpsriemic and hemorrhagio. 

No. 12. Anterior small lobes of lungs hepatized; no pleuritis. Peritonitis. Hem- 
orrhagic inSammation of a portion of small intestine. Pigmentation of large intes- 
tine ; indurated uldsrs present. Lymph glands bemorrbagic. 

No. 13. Jaly 31. Partial hepatization of lungs with necrotic foci; pleuritis; 
bronchitis; peritonitis. Hypeitemia of large intestme; ulceration slight. 

No. 14. August,4, GelatinousoBdemaoflpft fore limb. One-half of Imig tissue hep- 
atized with many necrotic foci; pleuritis. Hemorrhagic iudanim&tloo. uC c^Kl^awi^a.. 
U-Ulcers in large intestine 



J 



68 

No. 15. Atelectasis of several lobes of longs ; no hepatisatlon ; bronchitis. Hem- 
orrhagic inflammation of stomach. Extensive alceration in large intestine. 

No. 16. Extensive osdema of left fore limb. (Edema of Inngs. Semm in both 
pleural sacs. Bronchitis. Lung worms. General swelling of lymph glands. Hyper- 
asmia of stomach with localized necrosis. Pigmentation and discoloration of small 
and large intestines. A few ulcers in the latter. 

No. 17. Angnst 5. Lungs nearly normal. Pericarditis. Peritonitis. Hypei»mia 
of stomach. Enormons inflammatory thickening of csdoam with deposits aronnd it. 
Spleen large. Lymph glands swollen, hypersdmic. 

The important question arises as to the trne nature of this disease. 
To the writer it appeared at first like hog cholera, possibly like a mixed 
outbreak of hog cholera and swine plague. The bacteriological in- 
vestigations, however, did not confirm this opinion, based on the post- 
mortem appearances. As the investigation proceeded hog-cholera 
bacilli failed to appear in the cultures with certain exceptions to be 
discussed farther on, and indicated in the following table as motile 
bacilli : 



Case 
No. 



5 
6 

7 

8 

9 

10 

13 

14 
15 



16 



17 



Lnoga. 



Swine 
pla^nie. 

Nei^ative . 

Swine 
plague. 

Negative . 



Pleura. 



Negative 



Negative 

Swine plague. 



Negative 



Negative 

(Pericardium) 
negative. 



Spleen. 



Negative 

do . .. 

...do.... 
...do.... 



Swine pLigue. 

Negative 

Swioe-plague. 



Negative 

Swine-plagae 
and motile 
bacilli. 

Motile bacilli 
(bog chol- 
era?) 

Negative 



Liver. 



Negative 
...do ... 



Swine plague. 
(Peritoneum) 
swine plAgue. 



Swine plague 



Negative 



.do 



Kidney. 



Swine plagae. 



Negative 



.do 



(Peritoneom) 



It will be noted that in the eleven cases bacteriologically examined 
swine-plague bacteria appeared in only four. In these four cases they 
were detected in nearly all organs subjected to examination. Why they 
were not found in all cases may be due to several reasons. In the first 
place, former experience has shown that swine-plague bacteria are apt 
to remain localized, and that dissemination through the body does not 
always take place. If limited to the digestive tract they could not have 
been detected, because this was not subjected to examination. Secondly, 
swine-plague bacteria are short lived, even in cultures. They may have 
largely disappeared from the body at the time of death. Moreover, it 
is not improbable that many swine die from the secondary effects of the 
disease. (See No. 17.) The time of examination is therefore of import- 
ance. Swine may be infected all together within a short time, and the re- 
tarded deaths may be due to partial resistance followed by complica- 
tions. The lesions produced in the lungs and intestines may permit 
other bacteria to enter the body, which complicate still more oar under* 
standing of the real cause. 



Wbile therefore the bacteriological resnlta were raeager, the inocula- 
tion experiments ami one experiment iu which pigs were exposed to the 
disease were snccessful in demonstrating conclnslvely the pathogenic 
power of the swine-plague bacteria obtained from this outbreak. 

ESPOStTKE EXPEEIMENT. 

The experiment in which healthy station pigs were exposed to those 
sent from Fleasautville in the same pen is particnlarly interesting. 
Five Station pigs (Nos. 3S3-387) were placed in the pen with the five 
infected pigs (Sos. 13-17). The period of exposure varied greatly, as 
may be seen from the table below. Kos. 384 and 385 received a thor- 
ough exposare so far as regards contact with the sick pigs, No. 383 a 
partial one, and Nos. 386 and 387 were placed in the infected pen only 
after all the sick and infected had died. 



No. 


J^nlyM. 


JolySO. 


Jul; n. 


Ailg.l- 


«,.=. 


Aaj5.a- 


i«-.. 


i».. 


BactorlolojTloal 


U 

18 


I 


5 


D- 












Swin..-pUg<iB 
terinT) 

NogBtiTB. 


; 


^ 


' 


X 










^ 






X 


D,.... 


38S 












£i:pa>»i<l.. 


5 


5 


DissAoKOBbSof 


EipoHfd.. 


' 


^ 


X 


y 



































The result of this exposure was the death of No. 385 of swine plague. 
In the lunga were disaeminate<l numerons hepatized foci undergoing 
necrosis. Tliere was considerable plastic pleuritis matting the lobes to- 
gether. In the digestive tract extensive hyperjeniia bordering on 
hemorrhage. Swine-plague bacteria were obtained from the lungs, 
pleural exudate, heart's blood, and large intestine. Cultures were al«o 
matie from the spleen, liver, mesenteric glands, and kidneys, to make 
sure that if hog-cholera bacteria were present they should not be over- 
looked, but none could be found. A clearer demonstration of the disease- 
prodncing power of swine-plague bacteria could not well be obtained. 
The importance of this case warrants the publication of the notes in 
detail : 

No. 385. Binok Essex grade, sged 3 months, placed in pen contaiuing Nw. 13 to 
17, inclusive, on July 3!J. FoudcI dead Aagiiet 9, nvtbei uiiexpeotedly, ufter a Hiukue>ia 
laeting but 2 dafs, and manifested by dnllness and refusal to eat. 

Examined a few hours after death ; liept on ioe in the meantime. An thn akin is 
rellecMd, the cnt subcutaneous blood vgbshIh discharge drops of dark lilood. In ab- 
dominal cavity nothini; abuormal. Pericardium tiiiakened, opaque, veatiels injected. 
Iieftlialfof heart linnl; contraoted. EcchyuinHes on the right aoiiole. Biglit side 
ttntains a pale olot iinljedded in a daik coaEulnm. 



J 



70 

Respiratory tract : Macosa of larynx and epiglottis congested. Mncosa of trachea 
covered with a very thin layer of translucent, very viscid macas. Bronchial glands 
enlarged, pinkish od Hection. Costal plenra of the right side discolored, thickened, 
overlaid by a soft grayish exudate ; its blood* vessels injected. Diaphragm similarly 
affected. The various lobes of the lungs lightly glued to one another and to the peri- 
cardium. Considerable pleuritic exudate on the right ventral and along the edges of 
both principal lobes. Lungs in general hyperffimic. Left cephalic lobe emphysema- 
tous; left ventral shows hemorrhagic spots near its tip and contains two lirm nod- 
ules, appearing as yellowish spots under pleura. Left principal lobe contains four 
of these spots corresponding to firm nodules in the parenchyma. Besides these, a 
wedge-shaped, very firm, hepatized mass extends inward from the edge and almost 
through the depth of the parenchyma. These various masses appear yellowish, homo- 
geneous, imbedded in hyperaemic, air-coutaining tissue. They vary from one-eighth 
to five-sixteenths inch in diameter, nearly all of them situated near the surface. The 
largest ones are covered by roughened, thickened pleura, thrown into wrinkles ; these 
are in part yellowish, in part bright red and pink in color. The three lobes of the 
right lung contain these necrotic masses. There are several in the right cephalic, 
about six in the ventral, and over a dozen in the principal lobe, the largest being 
one-half inch in diameter. 

Digestive tract : Several small superficial sloughs on dorsum of tongue, near tip. 
Stomach contains a considerable quantity of food. Fundus deeply reddened over an 
area 5 inches in diameter. Duodenum with its mucosa bluish-gray, pigmented. Foy- 
er's patch showing as an aggregation of small, depressed pigment spots. Arbores- 
cent injection of jejunum merging into a general hyperaemia lower down. About 18 
inches above valve a patch of mucosa 2 inches long, intensely reddened. 

Extensive pigmentation of mucosa of cseoum. Mucous glands at the valve dis- 
tended with plugs. About 12 inches below the valve the mucosa is intensely red- 
dened, merging on hemorrhage. A very delicate elastic membrane (fibrin f) covers 
this region, extending for about 12 inches down the colon. Below this latter point 
the mucosa continues more or less hyperaBmic and pigmented into the rectum. Mes- 
enteric glands enlarged with cortex and interlobular portions hemorrhagic. Meso- 
colic glands in the same condition. 

Kidneys with cortex pale, somewhat enlarged. Otherwise no marked changes ob- 
served. 

Spleen slightly enlarged and softened. 

Bacteriological examination includes the following organs: 

In two necrotic foci of the lungs examined a number of minute oval bacteria with 
polar stain were observed in cover-glass preparations. Plates prepared with a bit of 
this tissue remained sterile, however. A rabbit inoculated subcutaneously with a 
bit of necrosed lung tissue at 3 p. m., Aug. 9, was found dead next morning. In the 
spleen and heart's blood and in cultures therefrom only swine-plague bacteria de- 
tected. The cultures were inclined agar and bouillon. 

In cover-glass preparations of pleural exudate, a large number of swine-plague 
bacteria were detected. Two inclined agar and one bouillon tube inoculated at the 
autopsy. One agar remained sterile, the two other tubes developed into pure cul- 
tures of swine-plague germs. 

From the spleen agar plates prepared with a bit of pulp remained sterile. A bouil- 
lon culture contained a large spore-bearing bacillus. From the liver, the same prep- 
arations made. Both plates and bouillon remained sterile. 

From the contents of right ventricle two agar and one bouillon tube were inocu- 
lated after scorching through the wall. The bouillon tube remained clear. Both 
agar tubes contained subsequently a grayish glistening growth of swine plagne 
bacteria. 

From a mesenteric gland one agar and one bouillon tube inoculated by scorching 
the surface and removing with small scissors bits firom beneath this area. Both tubes 
remained sterile. 



71 

Prom one kidney two agar platea and a bouillon tnlip j>rppara(l. Plate A t 
spoilt by an i^xtensive snrface growth. On Plate I! about 1*2 colonies developed, 
»>iiiQ made itp of micTococci, eouie of baailli. The bacilli on plate B were examined 
more closely and ruadil; dilVerentiated from hog-cholera bacilli (hitcifriMcolioantiuuniH) 
in gelatine rolls and aubcultiireB therefrom. The bouilloD ciiUuro conttkined a large 
spore-bearing bacinns. 

From the hypertemio mncosa of colon agar plates were made, which, however? 
(!;ave no inforinatiou aa to the presence of awine-plagne bact«ria. A rabbit was in- 
ocniated b; injecting under tlie skin a few drops of scraping from the colon stirred 
up in sterile water. Rabbit fonnd dead on the second morning. In cover-glaea prep- 
aralious and onltores froni blood and spleen only swine-plagiio hnctiria detnoted. 

The four remainiiig pigs did Dot die, but they were ill for a time and 
remained in a very unthrifty condition. They were killed abont three 
months after exposure. No pathological changes were observed with 
the e!ccL>ption of slight hypersemia in the dnodenum and a few small 
areas of collapse iti the lobes of the right Inng of 384, aud bronchitis and 
collapse of the entire right cephalic lobe in 38G, In 387 the solitary 
follicles of the colon were swollen; from some a curdy mass could be 
expressed through a central depressed opening. 



Besides the successful production of disease by simple contact with 
diseased animals, a considerable number of inoculations upon pigs were 
made, the earlier ones to test the pathogenic power of these bacteria, 
the later ones iu carrying out vaccination experiments. Only a [tortion 
of them are given below ; 

On October 30, two pigs (Nos. 399 and 404) were fwl thechopped viscera 
of six rabbits which had been inoculated subcutaneonsly on the preced- 
ing day and had all succumbed during the night. The viscera, which 
coutained immense numbers of swine-plague germs, were readily eaten 
after being mixed with a small quantity of feed. The pigs remained 
well. 

On the same day the following inoculations were made: 

Pig No. 403 received a subcutaneous injection of o^ cubic centimetres 
of a peptone bouillon culture of swine-plague bacteria 2i hours old, 
one-half injected into each thigh. 

No. 400 received into a vein of the leg 1 cubic centimetre of the same 
culture. 

No. 403 received into a vein of the leg 5 cubic centimetres of the same 
cnlture. 

No. 401 received into the right lung, through the chest wall, 5 cubic 
centimetres. 

These pigs were black pigs (Essex and Berkshire crosses) about 3 
months old. The bacteria originally derived from case 15 had been 
passed through a number of rabbits and guinea-pigs since Augusts. 

No. 402 showed no signs of disease after the inoculation. No. 403 



72 

died first. The inocalation took place at 3:30 p. m., October 30, and 
the animal was found rigid at 6:30 next morning. 

General blash of the skin on the ventral aspect of the body. On right side the 
small vessels of the snbcntis filled with blood which oozes from the cat ends in the 
form of thick drops. Both superficial inguinal glands hyperasmic. 

A small quantity of yellowish sernm in the abdominal cavity. A network of 
delicate fibrils stretching across coils of intestine. Peritonenm dall, opaqae in ap- 
pearance. 

Trachea and bronchi contain reddish froth, mucosa reddened. Panctiform henior< 
rhages under the plenra of loft lung. Slight general oedema of both longs ; some 
interlobular cedema of the ri^ht. 

Stomach contains a moderate quantity of deeply yellow-colored liqnid. The 
mucosa covered with a thick layer of tenacious mucus. The furidas over an area 8 
inches in diameter is intensely hypersemic, the intensity boin^; greatest in the center 
of the area. Contents of duodenum of a blackish color. More or less hyperssmia 
throughout the small intestine, with swelling, hypeniimia, and ecchymosis of Foyer's 
patches. More or less hyperasmia in patches in the csBCum and colon. The glandular 
patch at the valve especially reddened. Feces dry. Follicles show as circulary red 
spots from the serous side. Lymphatic glands of the lesser omentum, mesentery, and 
meso-colon very much reddened. 

Liver congested. Bile thicker and darker than normal. 

On surface and throughout the cortical portion of kidneys numerons pnnctiform 
hemorrhages. Pyramids intensely congested. Glands at hilus with cortex hemor- 
rhagic. Bladder contracted, empty. 

^No. 401 died in the evening of October 31, i. e.^ somewhat more than 
24 honrs after inoculation. It was placed in large refrigerator until 
ne^t morning. 

Subcutaneous vessels as in No. 403. Small patches of a grayish, viscid exudate on 
the large intestine, liver, and spleen. Pnnctiform ecchymoses barely visible to 
naked eye under serosa of large intestine. Arborescent injection of the subserous 
vessels on ventral wall of abdomen and intestines generally. 

In the right pleural sac a considerable quantity of blood-stained liqnid and shreds 
of exudate stretching from lung to chest wall. The various lobes of both lungs 
glued together and to pericardium. The lateral, ventral border of both lungs have 
the pleural covering much thickened, roughened, and thrown into wrinkles. Both 
lungs congested and oedematous. In the right cephalic lobe a mass of dark red 
hepatized tissue which may be the place whore needle punctured. Grayish-red 
hepatization of the major portion of left ceplialic lobe. Trachea and bronchi contain 
a large quantity of reddish foam. Mucosa with minute vessels injected. 

Pericardium opaque and roughened. The entire opicardium similarly affected. A 
grayish membranous exudate about the base of the heart extending upon the large 
vessels. 

Stomach contains a moderate quantity of turbid, saffron-colored liqnid; mucosa 
covered with a thin layer of mucus. Punctiform reddening of fundus. Small intes- 
tine contains much yellow liquid, mucosa not altered. Large intestine contains 
firm feces. No lesions observed. 

Cortex of kidneys rather pale, pyramids very dark red. 

Under capsule of spleen, some small extravasations. Parenchyma pale, organ not 
enlarged. 

Cover-glass preparations from peritoneum of small and large intestines and of liver 
show many swine-plague bacteria. In the spleen their presence not determinable on 
cover-glass preparations. Cultures contained them, howevez; 



73 

No. 40O became very sick on the day followinia; the inocnlatkii]. It 
was Quable to rise aiid showed nignt; of distress wben disturbed. It 
continued to lie qiiietly until Tfovember 3, when it died at noon, abont 
4 days after tlie iaocalation: 

Animal in yery good oondition ; abundance of Bnbantnnpnns fat. Blotxl vonnelH of 
anbcutia as in preceding coisea. In alxlominal carity nothing abnormal. 

Donhto pleuritia witti adhesion of various lolies of InngH to each other, to chest 
wallaod pericardium, Grajish mf^mbranous eindate over the ribe on the right side. 
The subjacent pleura has a bliiisli appearauoe. The correspondiog plenra of lung 
covered b; patches of similar exiidalu. The right long dark, red tliToughont but not 
hapatiijed. In the left Inng tlie ventral thin! of the ventral lobe is dark red, solid; 
on section grannlar and interspersed with grayisb areas. The lateral edge of adjacent 
prinoipal lobe is likewise he patized for a distance of 1 inch inwardand 2 inches alon^ 
bonier. 

Perioiirdiiim thiofceiied, opaqnc, rnngliened ; blood vessels injected; entire epicar- 
dium covered with a ratlier thick false membrane, loiisel; afiacbing the pericnrdinm 
to it. Large quantity' of dark, partly coagulated blood in right heart; a very little 
in the left heart. 

Stomacb empty, lined with a thin layer of bile-st-alned mncus. In the lower ilenm 
several patches of mucosa of a dark bluish color, each about 6 inches long. Large 
intestine filleil with dry, firm feces. In tho nppor colon, mocoaa \a Blate-colored, 
lower down normal in color. 

Liver rather 6rm, snrface appears slightly rouLfhened and mottled, owing to conges- 
tion of individaal loholes. Tbese deeply reddened lobules disserniuated throngh 
whole parenchyma. Hepatic vessels contain muob thick dark blood. 

Kidneys considerably enlarged, Che «nrFace twiset with a large number of grayish, 
slightly elevated spots, some surrounded by a dark-red kooo. They vary from one- 
half to one-fourth inch iu ilianiuler and are about one-foartU inuh apart. On sec- 
tion they correspond to grayish wedge-shaped masses extending inward through 
the cortex and in the form of longitndinol strite through the pyramids to the papillm. 
These infarets are made n|>, exauiinod fresh, ohielly of pus corpuscles. 

Only the spleen of this cane was sobjeotod to examination. No germs were seen in 
oover-i;Iass preparations, bat they were obtained in cultures. 

Sections were prepared from the hepatized lung tissno hardened in alcohol and 
stained with alnm-carmine and methylene bloc. The alveoli were found completely 
occluded with cellular masses partaking chiefly of the character of lencocytes. The 
red blood eorpnscles wore present in small numbers. Fibrin not deteoted. The 
alveolar capillaries distended with red corpnscles projecting into the lumen of the 
alveoli. In the cell masses swiue-plngue bacteria are very abundant. They are 
scattered between the cells, not iu clumps. 

Sections from the kidney hardened in alcohol and stained with methylene blue 
showed the cellular inliltration in the cortex and extending through the medullary 
portion in the form of cylindrical cell masses occupying the lumen of the large col- 
lecting tnbules which are complet-ely stripped of their epifieliam. 8wine-plague 
bacMrta are disseminated through these cell masses as in the lung tissue already 
described. 

The foregoing notes indicate that 5 cubic centimetres of a peptone 
bouillon culture of swine-plagiie bacteria injected into the circulation or 
the lungs may be fatal within 24 hours. They also show a tendency to 
intlammation of the large serous cavities, especially the pleural, even 
when the in)ection is made into the circulation. Thi:^ inflammation cor- 
re»poad8 closely with that found iu the disease as it occars in nature. 



74 

Another important fact is the production of pnonmonia not only when 
the bacteria are injected into the langs, but when introduced into the 
circulation. 

Feeding and subcutaneous inoculation failed to produce disease. 
That the latter will now and then produce disease is well shown by the 
following case : 

Pig No. 454 was inoculated February 28, 1891, with a peptone bouillon 
culture of the swine-plague germ from Case 15. Three cubic centimetres 
were injected subcutaneously into each thigh. The culture was one 
day old, prepared from an agar culture. (Three others inoculated at 
the same time remained well.) The pig was found dead March 2, in the 
early morning. It had thus lived between 36 and 48 hours after the 
inoculation. 

Black and red female pig, weighing about 50 pounds; in good condition. Consid- 
erable reddening of the skin of ventral aspect of body and ears. Subcutaneous fat 
reddened. From the cut vessels dark, thick bloo<l exudes. Over both inoculated 
thighs the subcutaneous vessels are extensively injected, forming a dense network. 
The subcutis has a glistening appearance. On the right thigh, near Poupart's liga- 
ment, the subcutaneous connective tissue is thickened, yellowish opaque, and iriable, 
over an area of several square inches. 

On opening abdomen the intestines appear very much reddened. A few elastic 
fibrils stretched across coils and about 10 cubic centimetres of turbid serum present. 

Stomach contains a large quantity of food. Mucosa not affected. Considerable 
catarrhal inflammation of the duodenum, which extends into jejunum. The hyperaB- 
mia extends through the small intestine, but much less intense. Several ascarides 
present. The mesenteric glands somewhat congested ; in two of them old, caseous 
masses, occupying nearly the entire gland. 

Large intestine contains a large quantity of semiliquid feces. Mucosa normal. 
Meso-colic glands hypersDmic. 

In each pleural sac about 10 cubic centimetres of turbid effusion. Lungs hyper- 
semic and oBdematous. Interlobular tissue of anterior (or cephalic) lobes slightly 
thickened and opaque, the result of some former inflammation. In trachea and 
bronchi some reddish frothy liquid. The mucosa shows marked injection of the 
minute blood-vessels, in some places almost hemorrhagic. In right bronchus a small 
number of large lung worms. 

On left auricle of heart ecchymoses. In left ventricle a small quantity of rather 
thick dark blood. Right ventricle distended with it. Coagulation feeble. 

Liver quite pale generally, acini distinctly outlined. Parenchymatous inflamma- 
tion. On the surface may be seen with a hand-lens numerous minute grayish>yellow 
dots, one or more in a lobule and situated chiefly on the periphery. In sections of 
fresh tissue they appear as irregular, opaque, amorphous patches. In stained sections 
from tissue hardened in alcohol they appear as intralobular aggregations of round 
cells occupying the place of parenchyma cells. These foci are probably result of 
some former disease. In the intralobular capillaries occasional masses of swine- 
plague bacteria detected. (See PI. xi. Fig. 4.) 

Spleen enlarged and hypersBniic. Kidneys with cortex broadened. The base of 
pyramids somewhat darker red than normal. 

In cover-glass preparations from blood and spleen, swine- plague bacteria present, in 
the blood in considerable numbers. 

From a bit of spleen pulp two agar plates prepared. On the first, after 24 hours, 
numerous swine-plague colonies appeared ; on the second nothing developed. 

Agar cultures from peritoneal and left pleural cavity remained clear. 




An agar tnbo inociilntetl From the blood contained a large nnmlier of conflnBnt 
I'olonisa. A booilloD tube became Eaiatlyoloaded. Both oontained only awtue-plague 

Aq agar cnltnrefrom tbe liver inouulated with ptatinnm wire oontaiued on the fol- 
lowing da; a ooDsiderable nnmber of Bwiue-plagiie oolonieH. 

Two of the following cases are of importance owing to tlie peculiar 
lesions of tbe joints caused by the inoculation. 

November 11. With a peptone bouillon culture of swine-plague bac- 
teria from the same stock culture (Case 15) the following inoculations 
were made: Nos. i05 and 408 received into a vein of one hind leg one- 
half cubic centimetre ; Nos. 406 and 407 received oue-fourth cubic centi- 
metre. In each case the quantity was diluted with sterile bouillon so 
that 1 cnbic centimetre of liquid was iujected. 

For the two following days all pigs were sick and refused to eat the 
food set before them. Within a week Nos. 406 and 408 had nearly 
recovered, No. 405 partially, while No. 407 was unable to get up and 
continued so until it was killed, December 3, by a blow on the head. 
Its chief lesions were a peculiar necrotic and suppurative condition of 
the joints and suppurative pericarditis. 

Condition of animal very poor. Enlargemout of tbe left carpal and phalangeal 
joints, of the right elbow joint, and both honk jointe. Along the inner aspect of the 
left scapula, largu inasEieH of ;nllowieh dr; pus deposited around tbe muscles. Carpal 
joint of the same liinb much eal urged. On opening the joint a considerable q^an^ity 
of dry pus is found deposited aroucd the bones and between the teuilims over tlie 
joint. The joint surfaces are discolored, tbe cartilages in part detached, and tbe 
sniall bones readil; crnehed. The toes enlarged, the enlargement due to similar sup- 
purative changes around the phalanges. 

Eight elbow joint enlarged; joint cartilages grecninb, opaqne. Aronnd the joint 
saveral abscesnea containing either a tnrbid liquid or dry cheesy pus, which has hnr- 
rowed. along the intermascnlar septa of the forearm. Carpal and metacarpal joints 
of this limb not afieoted. 

On bi>th hind limbs the tarsal and metatarsal joints very much enlarged and in the 
same condition as those ju8t described. In a Hwall autijbcr of rit>H the sternal articU' 
lation involved in HUpiiiirntion, Over tbe lower ribs on the right side tbe intermus- 
cular septa are imbedded in massos <if dry oheesy pas. 

Within tbe lymphatic glands at the angle of the jan and in the inguinal region Me 
minnte yellowish masses. 

Lungs normal. Pericardium thickened, adherent to tbe heart surface by means of 
ft layer of brittle, straw-colored pus, covering tbo entire heart surface with eioeptiou 
of a small area on the left ventricle, to which tbe pericardium is attached by means 
of delicate fibrous tissue. The pus is mont abundant at tiie base. 

Tbe digestive tract free from inflammatory changes. Storancb coutaina a sniall 
quantity of liquid of a deep yellow color, and some mucus. 

Kidneys show uu the surface a small number of discolored, slightly depressed spotA, 
corresponding to pale, whititili, wedge-shaped infarcts, extending into medullary 

Liver discolored in spots and patches on tbe snrfaoe. These qIho seen in sections. 
Gall bladder contains a dark-greenish solid mass, cutting like firm cheese and filling 
up the entire space of the bliidder. 

One tarsal Joint saved and opened for bacteriologioal eiamiuatiou. The skin is 
removed, the sac of the abscess thoroughly scnrcbed and opened tbrongb the simrcilied 
uea with a darned knife. A considerable quantity of greeoisli-yellow ltq.Did holding 



J 



76 

in RnRpeDflioQ brittle masfWR of pas wells ont. From this liqnid one inclined a^ar, one 
bouillon tabe, and three agar plates prepared. The agar and the bonillon tnbe con- 
tained active growths of the injected swine-plagae germ. On the first agar plate 
an immense nnmber of minute colonies appeared; on the second about two handred, 
and on the third very few. From these plates all colonies examined were made ap of 
swine-plague bacteria. 

A rabbit inocalated snbcutaneously with a particle of the pus died within 30 hours. 
In cover-glasH preparations from liver and spleen, and in an agar culture from the 
latter organ, swine-plague germs demonstrated. 

Another case of suppurative changes in the joints following intra- 
venous inoculation is the following: 

No. 411 received, December 4, 1^ cubic centimetres bouillon culture of swine- 
plague bacteria into a vein of one hind limb. It immediately became very sick, was 
nnable to get up, and died December 22. It. was greatly emaciated. Both carpal 
and the left tarsal joint enlarged, the changes within the joint similar to those 
described in the preceding case. Several rib joints in the same condition. In this 
case also the presence of the virulent swine-plague bacteria in one diseased carpal 
joint was demonstrated by inoculating two rabbits with pus therefrom. Both suc- 
cumbed within 20 hours to the inoculation. In the organs the characteristic polar- 
stained bacteria. An agar and a peptone bouillon culture from the spleen of the pig 
remained sterile. 

Two other pigs inoculated at the same time and with the same dose 
died in 15 hours with commencing peritonitis, pleuritis, and pulmonary 
cedema. In both the stomach was hypersdmic. 

PATHOGENIC EFFECT ON SMALLER ANIMALS. 

The great virulence of the swine-plague bacteria from this outbreak, 
as compared with those of former outbreaks, is even better shown by 
the inoculation of small animals. In the notes given below it will be 
seen that not only rabbits but guinea-pigs and pigeons succumb to very 
small subcutaneous doses of the growth from cultures, while large 
fowls are killed by inoculations into the muscular tissue. The inocu- 
lation of guinea-pigs and pigeons with cultures from previous outbreaks 
was usually uncertain even though rabbits invariably succumbed. 

Guinea-piga. — October 2, 1890. One guinea-pig received snbcutaneously into the 
thigh one-fourth cubic centimetre of a peptone-bouillon culture of swine-plague bac- 
teria, a second one-twelfth cubic centimetre, and a third one twenty-fourth cubic 
centimetre. The liquid in each case was diluted with 2 parts of sterile boniUon, 
hence 3 times this quantity of liquid was actually injected. 

The second guinea-pig died within 24 hours. At the point of inoculation consider- 
able gelatinous cedema, the blood vessels injected^ and the muscles of thigh covered 
with a thin, grayish layer. Stomach and small intestine hypersBmio. Spleen en- 
larged, dark colored. In blood, spleen, and liver very few bacteria. An agar culture 
from the spleen developed only colonies of swine-plague bacteria. The first guinea- 
pig died several hours later with similar lesions. Peyer's patches hypersemic. A mod- 
erate number of swine-plague bacteria in the various organs. The third guinea-pig 
died in about 36 hours with the same lesions. 

October 7. A guinea-pig was inoculated with one one-hundredth cubic oentimetre 
of a peptone-bouiUon culture. It died in 40 hours. The small intestine very hyper- 
sBmiCy occasional patches of punctiform hemorrhages in mucosa. A small number of 
bacteria in the various organs not showing a distinct polar stain. 




77 

October 14. Two guiuea-pigB were ioonnlated, one with one one-tlionsandth onbic 

jntiraetro uiiil tlie otlicir with oae forty-tlmuaandth cubic ceutimotrB of a peiiluLie- 
BlWDillou oultnre. The first died in 36 to 40 lioutv, the iMCund in 8 daya. In this 
■latter case there was ooDBiderable purulunt tliicliening of the Hubcutis arouDd tlie 
Eplace of iDJButiun. The iuteHtinuB, liver, and spleen covered byathiii layer of cellu- 
ft]Br and librinoua exudate. Very few bacteria in the variaua ui'guus and the exudate. 

KumeroUH additional iuooulatioua of very huiuU dosea into guinoa-pifja couHnuBd 
Kibe fatal eSect of this orgatiiHia on thiaspecies-of imimals. 

ifioe.— November 15, 1690. Two gr&y inioa inoculated with one or two dro|iH ci( 

,_ peptoDe>bouilIon culture died wiHiinSOhanrs. In tbeapleen nnmerons awine-plajpie 
bacteria which ahow the polar atain very well in stained preparationa. 

Figeont.—Vo. 1 inoculated by an injeutioa of 0.3 cubic ceuttmetre of a turbid ena- 
penaion from nn ngar culture 24 hours old. The iujectiou wua luodu uiitler the akin 

^«f one pectoial niiiaole. Pigeou No. S iiiouuUted iu Ibu Hame way with 0.2 cubic 
centimetre, the needle of the syringe penetrating snperficially the pectoral musole. 
No. 2 died uext morning. Parboiled appearance of inocnlatBd mnscle. Livet 
)»niarkably pule and lirai. In blood and liver immense nuiubcrs of bacteria ahoning 
polar atain very beautifully. 

No. 1 dies iu S4 hours. Slight subcutaneons infiltration at point of inoculation. 
Liver ia aame condition u in No. 2. Couaiderahle hypora^mia of mucoaa of duode- 
DL and adjoining amall inteatiue. Contents stained ruddiah. Bacteria uot so nuruur- 
I OH in preceding case. 

Tbeae inoculations having; proved siiccesaful, two pigeons were inacniatud with very 
tuall doaes from an agar culture from pigeou No. 2, three days old. 
' No. 'i. Skin over pectoral Incised with a lancet and a loop dipiied into the cnltnre 
tsd rubbed into anbcntia. 
No. 4. Skin tuciaed and a minute portion on platinum wire rubbed into aubcutis. 
Both dead next uiuruing, i. e,, witbia 18 houn. Bacteria abundant as in preceding 
Livers pale and firm. 
. Fowls. — Two adult hena, inoculated iu the aame manner as pigeons Noh. 3 and 4, but 
Villi a aliglitly inortaaed (quantity on the platiuum loop, remained iLiiflffocted. 

Two other ailnlt hens wero iaocutatod with the same bacteria from an agar culture 
suspended in bouillon until turbid. A hypodnnnic syringe was used au<l the nevdle 
pasaed superUcially into the tibors of the pectoral mnacle. Oue fowl received one- 
fbnrtb cnbio centimetre, the other one-half cubic centimetre. 

Thefiiat died in 94 lionnj. No local reaction perceptible. The liver ia very pale; 
qirinkled over it many wbitish points, character not determinable. Intesti nits nor- 
mal except ceeoa, which have some ecchymoses under serosa. Large number of bac- 
teria in blood and liver showing polar staining very well. 
fXhe aeoond fowl died iu 36 hours. Liver very pale and sprinkled with c'cchymoses 
ong the course of the superlicial vcauels. Iu liver few, in blood large numbers of 
lB ii^ected booteriu. 
T 



WO BACILLI ISOLATED KROM THIS OUTBREAK CLOSELY EESBM- 
BLIMG HOGCHOLERA BAOILLL 



The facte thus far given are sufficieut to prove that in this outbreak 
the awiiie-plague bacteria were the chief if not the only cause of the 
epizootic. Iu the oourHe of the investigations two kinds of bacteria 
were obtaiued, which deserve special atteution owing u> their resem- 
blance to hog-cholera bacilli. 

Owing to preoccupation of the writer with Texas fever investigations 
the cultures froai eases 13 to 17, inclusive, were made largely by Dr. V. 
Ia. Moore, assisCaut iu the laboratory, and he -«»& Avxvy^WS.^ft'fta.'a -sjftiaivji^ 



78 

attention to all motile bacteria having any resemblance to hog-cholera 
bacilli. Four of such were isolated, one from the lung of No. 14, one 
from the spleen of No. 15, one from the spleen of No. 16, and one firom the 
kidney of No. 385. These four bacilli the writ/cr subjected to a very care- 
ful examination. Those from Nos. 14 and 385 were found to be iden- 
tical with the common intestinal germ, bacillus coli communis. Those 
from the spleen of Nos. 15 and 16 grew very much like hog-cholera 
bacilli on gelatine plates and in rolls. To bring out the differences ob- 
served we will call the bacilli from Case 15 y and those from Oase 16 6. 

In gelatine rolls d could not be distinguished from a parallel roll cul- 
ture of virulent hog-cholera bacilli. The surface colonies of y presented 
a somewhat different type, in that they spread in a thinner layer with 
very thin edges, somewhat like baeillus colL They differed, however, 
from colonies of the latter by their very restricted growth, attaining a 
diameter of only 1^ to 2 millimetres. 

Both caused considerable turbidity of peptone bouillon, while viru- 
lent hog-cholera bacilli cause only cloudiness, which very rarely merges 
into a moderate turbidity. These bacilli multiplied therefore far more 
energetically in bouillon than do virulent hogcholera bacilli. There 
were other slight differences between these two bacilli. Thus, 
while y caused uniform turbidity of the culture fluid, d grew more or 
less in clumps, which caused a rapid settling of the growth in spite of 
the motility of the bacilli. When the culture was shaken up numerous 
clumps and flakes rose from the bottom. In the hanging drop these 
bacilli presented a strange appearance. The various clumps, composed 
of 10 or more bacilli, moved rapidly in various directions across the 
field of the microscope. This peculiarity of <^ maintained itself after 
passing through several rabbits and many cultures. In their patho- 
genic power these two bacilli differed not only from hog-cholera bacilli, 
as they are usually encountered in outbreaks, but from one another, as 
the following experiments show : 

Bacillus y. Plate cultures made from original culture and bouillon 
inoculated from a colony. When 24 hours old, this culture was used 
to inoculate 2 rather large rabbits. 

One white rabbit received subcutaneously 0.3 cubic centimetre cul- 
ture liquid. 

One black rabbit received into an ear-vein 0.3 cubic centimetre 
culture liquid. 

Two weeks thereafter, neither having shown any signs of disease, 
they were reinoculated. The black one received 1 cubic centimetre, 
the white 0.5 cubic centimetre, both into an ear vein. 

The white rabbit remained unaffected. It was killed after 16 days, 
but no lesions were found. The black one died in 36 hours. The blood 
was thick, • tarry; the left lung hypostatic; the spleen smaU. No 
bacteria in cover-glass preparations from the spleen. This result did not 
place these bacilli above the level of the ordinary ii^t^tinal bacteria 



[bacillKS ooli); for 1 oiibic. centimetre of tbe latter produces death in 
rabbits with equal promptDeas when injected into an ear vein. Two 
additional iutraveuouH iuouulatiouB were made April 28: 

One rabbit, weighing about 3 poiiuds, 0.3 cubic centimetre buuillou 
culture. 

Two rabbits, weighing about i pounds, 0.6 cubic centimetre bouillon 
culture. 

Both rabbits remaiDed apparently unaffected. 

Finally, on May 21, two rabbits, weighing each 3 pounds, were inocu- 
lated by receiving into an ear vein 0.6 cubic centimetre of a bouillon 
culture. The agar culture had been replated, nud from a colony this 
bouillon cultura waa prepared. Neither rabbit showed signs of disease. 

It did not seem woith while to spend any more time on this obviously 
son- path ogeuic organism. Its marked resemblance in morphological 
and biological characters to the hog cholera bacillus makes it highly 
probable that it is closely related to this latter germ. 

Bacillus S. Similar expurimeuts with this bacillus from case 16 
proved that this one did possess pathogenic properties, though feeble 
iu character. 

From the original culture a gelatine plate was prepared and a pep- 
tone bouillon tube inoculated from a colony. When 4 days old two 
small yellow rabbits were inoculated. One received about 0.4 cubic 
centimetre under the skin, the otlier the same quantity into the ear 
vein. The latter rabbit died in 6 days. 

The spleen la very lar^u, dark, aod tii>rteDDd, and oontains a large uiioiber of 
what appear to be bog-uholera haoilli. Tba liver Hhowa areas c>f necroflia. The gall- 
liladderattaolied by inflammatory exndatiou to the omentum. The liiiiga cedeuiatons. 
Fatt; degeueratioD af cortex of kidneys. Tlie email inteatioe Ulied with a glaiiy 
yeltowiab liqaid. The oaltQres fruio this case coatained only the injected bacilli, 
esbibiting iu bouillou tubes the peculiar characters described above. 

The ralibit which received the sabcutaueous dose remained apparently unulfeoted. 
Arter 22 days it was inoculated with uwiiie plague aud found dead the following 
morning. At the place uf the Brat iauciilatinu a cyst nearly 1 inch iu diameter con- 
(aiuing ouidy pus. lathe appendix vermiformis from twenty tu thirty wliitisli nod- 
ulea under seroaa. Similar nodules on Peyer's patch near ileu-caical valve. 

A rabbit which received an injection of 0.3 cubic centimetre into abtlo- 
inen remained well. When killed, 10 days after the inoculation, the same 
appearances of appendix of ciecum were found as those just described. 

Several weeks later, with the culture obtained from the first rabbit, 
four rabbits were inoculated, each by an injection into an ear vein of 0.3 
cubic centimetre. These all died within 36 to 48 hours. In the one 
which lived 48 hours the following lesions were observed : 

Large, dark spleen. Interlobular network of a yellowish color throngb the wbolt 
liver. Under the mtcroacope this appeared aa fatty degeneration of tlie periphery of 
the acini. Lungs cedematons. Left ventricle of heart in advanced fatty degeneraCiou. 
Cloudy swelling of kidneys. lathe spleen large nnmbBn of bacilli which appear 
somewhat larger than hog-cholera bacilli and are usually In pkirs, Cultaren franv 
^bis case uuntaiu only the injected bacilli, 



80 

Ttiat tUe bacillus S is an att«uuated variety of tlio liu^-cbolera ba- 
cillus caD not be doubtiMl wheu tliese rabbit inoculiitious are takeu into 
cODSideratiou. Tbere van, inureover, a gradual iocrease in virulence 
observed trom one inoculation to tbe mibseijueut one. Thus tbe first 
rabbit, whiub wasa small one, receivetl 0.4 cubic centimetre bouillon enl- 
ture into a vein, and lived 6 days. The second rabbit received 0.2 eubic 
ceutitiietre, and died ia 2 days. Subsequent inoculations sLowed that 
.03 cubic centimetre was fatal in a few days, while smaller quantities 
caused a disease from whiob the rabbits recovered. 

We have thus s€«u that in addition to the swiue-plague bacteria, 
which produced disease both after iuoculatiou and ex|x>snreto diseased 
swiiie, two motile bacteria were isolated from cases 15 and 16, but from 
no other. These both resembled hog-cholera biicilli very closely, and 
undoubtedly ure related to them. But they differed from each other in 
several particulars, notably in virulence. While the one from So. 16 
was shown to be an undoubted but very attenuated variety of hog- 
cholera bacilli, the one from No. 15, though it may ulao be an attetm- 
ated variety, has so little virulence that its bearing upon the outbreak 
in question must be reganled as entirely negative. As to tbe other 
bacillus the questtou is not so simple. It may be seriously doubted 
whether it had anything to do in protlucing tbe disease, since its pres- 
ence was detected in but one out of eleven cases, and since hog-cholera 
bacilli from genuine hog-cholera outbreaks appear quite regularly in 
cultures from the spleen. Moreover, the virulence of the latter is many 
times greater than that of tbe bacilli in question. Thus, to test this 
matter thoroughly, one pig received into the lungs 5 cubic ceutiniutres 
of a bouillon culture, another 5 cubic centimetres into the abdomen, 
and several others 7 cubic centimetres each directly into the blooil. 
None of them showed any signs of illneas after such treatment. Lastly, 
two pigs were ted,after afastof 34 hours, with200 cubic centimetres of 
a bouillon culture each. This feeding was repeated on two successive 
days. A slight diarrhea, lasting a few days, was the only visible effect. 

Ou the other hand it is not to be denied that tht><se bacilli may have 
occasioned a part at least of the intestinal disease observed in this out- 
break. The truth may be that these attennate<l hog-cholera bacilli, 
brought from distant outbreaks by individual animals which have sur- 
vived such outbreaks or proved themselves insusceptible at the time, 
had no effect on the animals brought in contact with them until the 
swine plague broke out, when they may have started into activity an<l 
contributed to the fatality of the disease. That the bacillua 6 from 
ciise 16 should have been the cause of the outbreak and the swine-plague 
bacteria secondary to it would seem very far-fetched in the light fur- 
nished by the experiments with the swine-plague bacteria. 

In addition to tbe attenuated hog-cholera bacilli, another disease 
germ was isolated from cultures prepared on tbe farm from some of the 
earlier cases. This germ is bnelly referred to in the autopsy notes as 
n rather larg'e bacillus, which multiplied in the condeuaatioQ water of 



81 

iigar caltaret) bat not on the surface, it prodaoea spores which are 
formed in the central portions of the rod. The latter during the de- 
velopmeut of the spore becomes spindle- shaped. This bacillus does not 
multiply iu culture tnhes under ordinary conditions, but requires media 
more or less free from oxygen. It belongs to the group of anaerobic 
bacteria, aud is probably identical with the bacilluH of malignant oedema. 
Whether it is the biicillus which I have frequently detected in swine 
and called "post-mortem" bacillus it is impossible to state, siuce I have 
made no special effort to cultivate the latter and test its virulence ou 
animals. 

The bacillus in question grows in deep layers of agar in test tubes. 
The isolated colonies develop quite slowly and after 1 or 2 weeks attain 
a maximum diameter of 2 millimetres. The surface of the fully devel- 
oped spherical colony is closely beset with radiating fluger-like projec- 
tions, which are perhaps one-fourth as long as the diameter of the entire 
colony. An additiou of glucose to the agar favors the growth of the 
bacilli and causes the production of considerable gas, which may break 
up the agar column and force portions nearly out of the tube. This 
bacillus also multiplies iu peptone bouillon containing, say, 2 per cent, 
of glucose, provided oxygen is absent. For this purpose the fermenta- 
tion tube, which I have found very useful in bacteriological work, is very 
U adaitted.* When such tubes are inoculated a faint cloudiness of 

• The feroieutation tnbe haij bean in use for miiiij yeara in various kinds of biolojfi- 
oal work. It.H Viitiie in biioteriotogical work as a culture tube I have alread; called 
l'«tteDtion to {CBntralbiatt /. Balcteriotogie {IS'M) Vll, p. 502), but reprodace here a few 
anggeutions an to itn uaa. Tha tube, lednced 
one-half, ia Hhowu in tbe accompaaying cat. 
After it baa been plugged with cotton wool 
and sterjlizeil in the dry hot airoveu it ia filled 
with tho unlture liquid and ttteutued ou threo 
suiMiessiva dayu. The air nolluuting at the top 
ne.ir b, which has been forced oat of the liquid, 
tthoitltl iiH retnovad iuiinailiately after eaoh 
GLeamiuj; by gently tilting the tnbe. A.fter 
tbe third steaming, the liquid in b ia entirety 
fretd of dissolved air. The tube ia inoculated 
with platinnni wire, loop, or pipette oa are or- 
dinary tubea. A large number of bacteria, 
eapei'.ially thoae living in tbe intestines of an- 
imala. are capable of setting np a fermentation 
wbeu ghieosu and other augnra are present. 
Tho fiiid uollacting at the top iu b is composed 
cbielly of COm and H. 

I liavo found the fermentation tul>e very val- 
uable in tbe diagnosia of hog-oholora bacilli, 
which arc capable of fermenting glucose, etc. 
Hog-oholera bacilli from a largo numberof oul- 
breakatested thus far all manifeatthiaphanom- 
ouon, and it may be safe to assert that any 
bacilli roaembllug bog chQl«a -kVuiV *^o -on«. 
produce gas Mft ■oot^ot^^'i^*'^'^^'*^^'*- 




82 

the liquid appears within 1 or 2 days, and gas bubbles rise in the closed 
branch. After a few more days the liquid in the closed branch is in 
part replaced by gas, which continues to form for a week or longer. 
Meanwhile the bacilli have become deposited in the bottom of the tube 
as a whitish, flocculeut mass. By cultivation in this way I was able to 
keep these bacilli alive for many months until opportunity offered to 
test them on animals. That they are pathogenic and may cause ma- 
lignant (edema the following inoculations are sufficient to demonstrate : 

May 22, 1891, 3 p. in. l?>oin a culture in a fermentation tube 14 days old one- half 
cnbic centimetre of the turbid deposit withdrawn and injected under the skin of a 
rather large guinea-pig in the region of the abdomen. 

The animal, apparently well at 9 a. m. next morning, lay down at 10 a. m., and died 
at 1 p. m. On examination very extensive sangninolent a)dema of the sabcatis over 
abdomen and part of thorax. On left thigh the oedema accompanied with macb dis- 
tension of the snbcntis with gas. The serosa of abdominal cavity discolored and 
vessels injected. Both sides of heart contain dark soft clots. In the blood-stained 
subcutis large numbers of the injected bacilli, in the spleen a few, in the blood none 
observed. Two fermentation tubes were inoculated with blood and a particle of 
spleen pulp, respectively. In both a typical growth appeared in a few days. 

At the same time a colony of these bacilli was removed from a glncose agar tube 
now 22 days old, and placed into the subcutis of abdomen of another gainea-pig 
through an incision. No symptoms observed until 48 hours, when the animal rested 
with abdomen on floor of cage and did not stir when aroused. Apparently neither 
drowsy nor in pain. It was found dead on the moruing of the third day (HO hours). 
The lesions as well as the distribution of the bacilli and cultures from blood and 
spleen were the same as in preceding case. 

A pig inoculated subcutaneously with 2 cubic centimetres of turbid deposit firom a 
fermentation tube showed no signs of disease. 

Whether these bacilli can be implicated in the death of some cases of 
this outbreak in which swine-plague bacilli were not detected, these 
inoculations will not permit us to decide. The bacilli at the date of 
inoculation had been cultivated for 10 months, and hence may have 
become attenuated in the meantime. 



At the end of 1890, Veterinarian B. O. Schroeder was directed by the 
chief of the Bureau to make some examinations of swine diseases in 
the West with the object of still further determining the distribution of 
hog cholera and swine plague. 

Among the several herds examined only one deserves mention, be- 
cause positive bacteriological results were obtained. This herd was 
found about 1^ miles south of Chillicothe, Missouri, where greater or 
smaller losses from infectious swine diseases are said to occur each 
year. 

Cultures were made by Dr. Schroed er on agar, and these were care 
fully examined by the writer subsequently. The cultures from one 
animal contained only swine-plague bacteria, those from another only 
hog-cholera bacilli This outcome again illustrates the caution which 



I 



muat be exercised in isoltitlng tlie bacteria obtained from diseased ani- 
maU, bo that tlie characters of two different bacteria may uot be 
confounded and regarded an one, as has probably been done by Bill- 
ingB in his investigations. No couclusiouH are drawn from the meager 
details below a^ to which bacteria may have been the predomiuating 
cause of the disease. They simply illustrate the wide diffusion and in- 
termingling of two pathogenic bacteria. 

The following brief synopsis has been condensed from Dr. Schroeder's 
noted of tbe post-mortem examination : 

No. 1. December 37, 1S9U. Dead Beveral days. Animal hod been opened by owner. 
SpleuD greatly congested. InteetineH coold nut be examined. Right lung aliuoat 
completely bepatizud. Epicarditis. Lymph glands in general mueb coufjeaCed. 

1.3. Jan nary 2, IttOl. SDvernl fociof hepatization in longs. Muae-puruleut cou- 
m of smaller air tubus. Spleen very large, dark, softODed. Patechia in oortiual 
ipoition of kidneys. Mnch niacas in stoniauh. Feoes in large intestine very dry, 
coated with mncus. Patches of byperiemia; no uleeration. 

3. January 3, On pnbio region a large open wound, with subjacent tlHsiie very 
much thickened by inflammatory deposits. Spleen very large, dark, and friable. 
Slight exudative peritonitis. Congestion of fnndua of stomach. Feces in large 
intestine exceedingly dry and covered with mucDs. Several inches below valve a 
blackish, necrotic patch, 14 inches long and a half-inoh vide (Foyer's patch T). Mucosa 
congested in isolated patches. No other ulceration observed. Langs hyperaimic. 
No hepatizuliun. Heiuurirhu{;iu condition of auricles of heart. Petechia on epicar- 
dium of ventricles. 

No. 4. January 3. Black female, killed by a blow on head. Splenn as in No. 3. Di- 
gestive tract normal, with exception of jiutcbea of cougestiou ii 
what appear ta be two SEuall ulcers ou iloo-ciBcal valve (enlarged n 
Slight exudative peritonitiH. Ltingsfree from hepatization. 

Bacteriological examination. From No. 1 no cultures made, owing to post-moltom 
ohaoges. 

From No. 2 bits of the spleen placed in two agar tubes. On Jannary 19 thore were 
about 100 isolated and confluent colonies on the agar snrface in one of the tubes. In 
the other no growth had appeared. These colonies were aarefiilly exaiuined and 
found to be swine-plague bacteria. Many of the colonies were dead, an tlie agar bad 
dried ont somewhat. Transferred to bouillon and other media, the diagnosis was 
confirmed. These bacteria were, however, more or less attenuated as regards patho- 
genic effect. 

January 31. Two white rabbJts of medium size inoculated, one subcntaneonsly on 
one ear with a loop dipped intocondtnBation watci of anagai culture, tbe otheinnder 
skin of abdomen in name manner. Both rabbits were very tiniet tor several days, tbe 
former with ear drooping and very much reddened. On the eleventh day it was 
Oliloroformed. The greater part of the inocnlated ear blackish ; bard, like a board; 
necrosed. A. purnlent inBamiuiitiou extending from ear down on the face and neck. 
Heart mnsole pale and flabby. Much fat in the fibers. Fatty degeneration of con- 
voluted tubes iti cortex of kidneys. Numerous granular casts in nrine. Spleen small 
and pale. Fatty oimdition of liver. 

The second rabbit was well at this time. When killed a. small abscess in subcotis, 
with eochymoais of contiguous abdominal muscles. No internal lesions. 

From No. 3 agar cultures had bi.'cn made from spleen and liver. Both developed, 
and evidently contained tbe same bacteria, Tbe liver culture contained a consider- 
able number of isolated ooloniea. From these gelatin plates were made. The vari- 
ous cnlture tests and tbe microscopic characters (size, motility, etc.), all pointed to 
liog-cholera baoillL Tbo diagnosis was ooufiruied by the fQllowiog inoculations: 



i 



I 



84 



iai veiD one-fifth ciibto uenliuieter boiuTluD cultan 
derived from a coliiuy ou a gelatine plate. Oue rabbit received eauie dusu of mtiue 
ouUure auder akiu of Hank. 

The flntt rubbit died wittiin 44 hours. No Incal lesion. Spleen very large, dark, 
and firm. Liver fatty. Lnugs slightly <Bdeiiiatous. In the Hpleen uumeroiiB bacteria, 
resembling bog-oliulera bacilli iu every way. Cultures oonfirniatury. 

TbeHUOOud rabVit died iu5dayii, At the place uf iuocutatlon purulent intiltration 
of akin and auliontia with ecohyuiwei on periphery. Spleen largo, dark, firm. Heart 
ninHcle fatty. liiingH cedeuutoua and byperiuniic! along ventral Iwrder. In liver 
intoi'lobalar tiwae broadened, pale, represeitting degeneration of periphery of acini. 
Cnlturee contain only hog cholera bacilli. 

E'ruiu pig No. 4 au agar culture trom the Hplocu failed to develop, 

XX. 

Au intermingling of hofr cholera aud Hwine plague was also observed 
in two ontbreaka studied in 1889, and very briefly referred to in the re- 
port of the Secretary of Agriculture for the same year (p. 75). These 
outbreaks are of imporUiDce, iu so far as the hog-cholera bacilli obtained 
therefrom were somewhat modlfieil with reference to their biological 
and pathogenic properties. It was evident also that these hog-cholera 
bacilli were the predominating cause of the disease in many of the ani- 
mals exposed, and the full report is therefore reserved for another pab- 
licatiou. The investigations are here mentioned to illustrate once again 
the wide <listributiou aud frequent iatermingUug of these two patho- 
genic bacteria. 




THE BACTERIA OF SWINE PUBDE. 



I 
I 






MORPHOLOGICAL AND BIOLOGICAL 0HABACTF.E3. 

If a cover-gliiNs preparation from tlie spleen pulp of a rabbit, wbich 
has aitccumbed 16 to 20 lionrs after inoculation, ba stained in alkahne 
methylene blue for a few [ninutea, and examined with a high power 
either in water or after it has been permanently mounted in balsam, 
a very large nnmber of swine-plagne bacteria will usually be found 
among the cells of the spleen pulp. 

These bacteria at first give the impression of very minute flattened 
cocci in pairs, the individuals of each pair separated from each other 
byasmallinterveiiiDgspace. {See Plate xi. Fig. 1.) A closer inspection, 
however, sbows that each pair is in reality a single elongated body of 
which the two cocci are the stained extremities. The intervening space 
is the unstained connecting body, the borders of which are contiu- 
uons with those of the stained estremities as indicated in the figure. 

The two end pieces have usually a hinar shape, the concavities turned 
towaM each other. The depth of the concavity varies somewhat and 
may even be replaced by a straight line, in which case the end pieces 
bave a hemispherical shape. 

It is highly probable that the bacteria as described above are in a 
state of division, the two stained extremities representing the two future 
cells, and the intervening space perhaps a common membrane without 
any contents. During this process the protoplasm retracts from the 
central portion of the rod anil gathers at the two extremities. 

In stained cover-glass preparations these bacteria are not infre- 
quently found varying in length. This variation is mainly due to the 
variation in leogth of the middle anstained piece. Thus preparations 
of the same germ from some rabbits may show a very short middle piece 
Bo that the two concave borders of the comparatively large end pieces 
appear to touch each other on the lateral margins of the bact«rium. In 
otlier preparations this middle piece may be from two to three times the 
size of each end piece. In a preparation from the spleen of a rabbit 
inoculated with the German swine plague the middle piece was in many 
bacteria so long as to suggest involution or degenerate forms. It made 
the entire rod one and one-half to two times longer than the normal 
forms. In some of these bacteria one end piece had divided and the 
double germ resulting therefrom appeared Ute a.Vo'ft?.,^^'^*'^ ^'wiw^^ 




t>aci1Ius, in which there were iti both ends and in the tnidiHe of the 
the deeply Rtained round coccus-like bodies. In all the variations 
stained e^ttreinities do not vary mnch in size. This is, therefore, an 
ditional reason why these extremities should be regarded as dan^hl 
cells in process of separation from one another. 

The foregoing description applies to bacteria taken directly from 
dead animal and dried on cover glasses. In this dried condition after 
they have l>een stained and mounted in balsam thoy are abont 1 n' 
long and 0.5 to 0.6 n wide. Their ends are rounded ofl' and in general 
their form is that of a somewhat elongated oval. Besides these aver- 
age forms there may be others, 1,8 ft long and 0,7 to 0,8 fi broad. Di- 
mensions larger than these generally belong to forms evidently abnormal 
in development. In these the width generally remains the same as thi 
of the shorter forms. 

While these bacteria in cover-glass preparations from pigs, inoculal 
rabbits, etc., are the same in appearance, the same bacteria in sections 
of tissues hardened in alcohol and stained in the same way <io not cor- 
respond to the description just given. They are smaller than the 
smallest forms described above, and as a loile do not show distiuci 
the nnstained middle piece. They appear under high powers as 
nute uniformly stained oval bodies. It is evident that 
the drying proeess has a tendency to Hatten objects out .tgainst 
cover glass, while in the hardening process there is a tendency to 
shrinking, which is not counteracted in any way. Hence the different 
appearance may be due simply to the difiFerence in the mode of pn 
aration. 

The foregoing description applies to virnlent varieties which cai 
death of the inoeatated rabbit in 16 to 20 hours. In the varit 
organs and the blood the inoculated bacteria are present in large noj 
bers. The more attenuated varieties do not produce death thns quick] 
The rabbit dies in from 3 to 10 days. The bacteria have meanwl 
become localized in the peritoneal cavity or the pleural cavity, ai 
produced an inflammatory exudate which contains immense nnmtters 
bacteria. These do not stain so well as those described, and raref; 
show the polar arrangement of the protoplasm distinctly. There is 
reason to suppose that many of these forms are already destrojed by 
the infiamniatory process. 

In cultures the swine-plague bacteria are smaller than in the bodii 
of inoculated animals. Examined in water they appear so minnte 
it is with difRculty that they are detected at all {Zeiss apochr. 
metres, compens. oc. 4). In general they answer well to the desi 
tion of micrococci, although tbey are not round bat oval 
the border of the drop holding them in suspension the polar arranj 

Kmant of the protoplasm is occasionally detected, 
ine-plagae bacteria are non-motile. This important character 
• Uisromilli metre or about one tirenty-t 



Di- 

latejj^H 
tinns * 

: cor- 

n th e I 

iuctli^^H 

rJH 

St the I 



ire is 

d by 

icr^^^^H 



o thounatidlb of : 








I 



Berves to clistingiiisli tbem at once from liogcholera bacilli. In liqnidi 
au active Browniaii motion is freqnently seen which ia so violent at 
times as to give the impression of spontaneous motion. They do not 
change their place, however, and this agitation is thus readily distin- 
guished from the very iictive flagellar movemeiit of hog-cholera bacilli. 
Again, flagella are easily demonstrated on the latter. Dr. V. A. Moore 
has devoted much time in the laboratory to bring out flagella on swine- 
plagne bacteria without anecess. This was of course to be expected. 
No spores have been observed in any of the conditions under which 
they have been cultivated. -They are destroyed in liquids by a tem- 
perature of 58° C (13G.4° F.) ia 7 minutes. Their rapid destructiou 
by drying, disinfectants, etc., renders it highly probable that no spores 
are produced. 

The question whether swine-plague bacteria should be called bacilli 
or micrococci is not an easy one to settle satisfactorily. In the tissues 
and very rarely in cultures they may appear as elongated rods, but only 
under abnormal conditions. Their usual form, both in cultures and in 
sections from tisanes, is that of an oval, the longer diameter exc«ediug 
but slightly the shorter diameter. While we are inclined to call them 
micrococci as least misleading, nsage seems to have followed the Koch 
school in calling them bacilli. In the present report they are simply 
denominated bacteria, and the matter of nomenclature ia left open. 

Swine-plague bacteria are not so easily cultivated as hog-cholera 
bacilli. Besides refusing to multiply on certain media in which hog- 
cholera bacilli readily grow, their life in cultures is much shorter. 
In the following the chief characters of these bacteria in the various 
culture media are given somewhat in detail, since no one character 
is sufficiently peculiar, and all are necessary to positively recognize 
the species. 

The growth on nutrient gelatine is variable and therefore not reliable. 
The bacteria from outbreaks VII, VHI, and IX, as a rule, refused to 
multiplyin gelatine. Occasionally colonies develop in roll cultures, but 
the growth is very feeble and retarded, and may be overlooked unless 
they are carefully watched for longer than a week. An increase of 
alkali seems to favor their growth. 

If we turn to the bacteria discovered in 1S3C and 18S7 perhaps the 

only biological difference observable is the more abundant growth of 

these varieties in nutrient gelatine. The deep colonies were from one- 

fourth to one-half millimetre in diameter; the surface colonies were i or 

^^^ 5 times as large. The former appeared after some days with a pale mar- 

^^K gin, the central portion being brownish, granular.* The failure to grow 

^^^K on gelatine can not be regarded as entirely due to the lower tempera- 

^^^ft ture in which gelatine must be kept. It seems partly due to the nature 

^^^Bofthemedium, partly to the adaptability of the bacteria to bo cnltivat«d. 

I 



19 and Plate iv iu the report of the Bureau of Animal loduHtry fur IS^, 
V and I'latu xil, Fig. 'i, of tbia repurC. 



88 

The same method being employed in the preparation of gelatine and 
agar, the fact that swineplagne bacteria will develop in an a*gar tabe 
when a gelatine tube by its side inoculated in precisely the same 
manner fails to develop shows that some physical or chemical con- 
dition of the gelatine is at fault. The gelatine mast be regarded as a 
drier medium than the agar, which drjrness is not so favorable. An- 
other possible explanation of the refusal of the more recently cultivated 
varieties to multiply in gelatine may be due in part -to slight improve- 
ments and modifications in the preparation of nutrient gelatine and 
agar. On the whole gelatine should not be used in the investigation 
of swine plague. 

On nutrient agar prepared in the ordinary way with peptone bouillon 
and kept in the thermostat, multiplication goes on rapidly, so that in 
24 hours the deep colonies are one-eighth to one-fourth millimetre in 
diameter according to the proximity of the colonies to one another (see 
Plate xn. Figs. 1 and 2). The deep or submerged colonies appear 
roundish or lenticular, and when examined under a low power (about 
60 diameters) they are brownish, opaque, with margin and surface beset 
with small knobs, thus giving the disk a reticulated and the border 
an irregular wavy appearance. Some colonies do not present this 
appearance, but remain smooth on surface and margin. The surface 
colonies are glistening, slightly convex, whitish disks, barely trans- 
lucent. They are circular, with margin having no irregularities. 
Under a low power the central portion is brownish, granular, towards 
the margin becoming more homogenous and translucent and exhibit- 
ing usually very delicate radial striations. The deep colonies may 
attain a diameter of one-half to three-fourths millimetre; the surface 
colonies, when 1 centimetre apart, measure 4 to 5 millimetres in diameter. 
As in the case of other bacteria, the size of the colonies varies inversely 
as their number on the plate. 

A very characteristic feature of such plates is the strong, disagree- 
able, pungent odor which is emitted. This is best detected when the 
agar plates have been prepared in so-called double dishes, and these 
are quickly opened after they have been closed for 24 hours or less. 
When the growth is abundant this odor persists even after repeated 
exposure of the plates. 

On the inclined surface of nutrient agar in tubes, the growth may 
appear either in the form of isolated colonies or as a single grayish trans- 
lucent patch, depending on the number of bacteria rubbed upon the 
surface originally. (See Plate xn, Fig. 4.) The condensation water 
collected in the bottom is usually quite turbid within 24 hours. After 
two or more weeks it will be found that the growth in the water has 
assumed a viscid gelatinous consistency, so that it tends to come away 
in a mass when a platinum loop is introduced. This has been charac- 
teristic of all swine-plague germs thus far examined. 

Bouillon containing from one-fourth to 1 per cent, peptone becomes 




89 

nniformly but very faintly clouded within 24 hours. From some out- 
breaks the growth may be at first tlocculeat or granular. The bacteria 
grow in ohimps, leaving the liquid unclouded. Thia, however, is no 
permanent character, since cultnres of succeeding generations after a 
time become uniformly clouded. Not infrequently a partial membrane 
or a ring growth on the glass at the surface of the liquid appears after 
one or more weeks of quiet standing in a uniform temperature. In 
the bottom a deposit forma during this time which may become quite 
viscid. No marked changes in reaction occur in the cultures even after 
some weeks of multiplication. There seems, however, to be a slight 
tendency toward the production of an acid reaction in culture liqnids 
originally alkaliue. No fermentation of sugars accompanied by the 
liberation of gases takes j)lace. In thia particular these bacteria are 
distinguished from hog-cholera bacilli, which are able to cause fermen- 
tiition of glucose with liberation of hydrogen and carbonic dioxide.* 

Milk inocnlated undergoes no changes visible to the naked eye. The 
reaction becomes faintly acid. On the surface of boiled potato there 
is no appreciable multiplication. I have once or twice observed avery 
faint whitish growth which may have been duo to the culture material 
transferred. In general, however, swine-plagne bacteria do uot grow 
on potato. 

The temperature range for the mnlti plication of swine-plagne bac- 
teria may be placed between ((6° an<l lOS'^F. The growth is very 
feeble between ti~t° and 70° F., and most rapid and abundant be- 
tween 97° to 100° F. The nature of the culture media seems to have 
some effect. If this is very favorable ut u I ti plication may take place at 
a slightly lower temperature than when less favorable. 

Among the properties of the group of swine-plague bacteria pointed 
out by German observers, and valuable as a means of diagnosis, is the 
capacity to form in culture liquids indol (ChHyN) and phenol or car- 
bolic acid (CfiHnO). Both substances are also formed ordinarily dnriog 
the decomposition of albumins, and hence are present in the int^'stinal 
tract. 

The methwl followed in testing for these substances is that sug- 
gested by IiewandowHki,f which consists in distilling the culture liquid, 
say 250 cnbic centimetres of ordinary peptone bouillon in which the 
bacteria have grown for 10 days, with SO cubic centimetres of strong 
chlorhydric acid and testing the first portions of the distillate for indol 
and phenol separately. For indol 3 cubic centimetres of a 25 per cent 
solution of sulphuric acid is added to 5 cubic centimetres of the distil- 
late, and then 2 to 3 drops of a 0,1 per cent solution of sodium nitriip. 
A reil coloration indicates the presence of indol. A fine crystalline 
precipitate forming immediately, or soon after the addition of bromine 
water to the distillate, indicates the presence of phenol. 




I 



The metliod followpd Tty tlie writer was practically tlie same, except- 
ing tbat i>otassiuui nitrite was URed, the eolation t)eing prepared I'resh 
eiHch time. A preliminary trial having shown phenol iu most cultures, 
but only a trace of indol iu one culture, a second test was made. 

Sliglitlj' alkaline LouilloD rontainiDg 1 pnr codI. po|it«ne and ooe-hiilf ^i«rcent salt 
was 8teriliE«d in Daakx CDCtaiDing 200 cul>ic ceiitimutreH «Acb. and iuoculiit«d May 
15, IS'Jl, with Bwifle-plague liacMria from tha foliowiug sources : 

1. Oatbreak: Til. 

2. Outbreak VUL 

3. Ootlireok IS. 

A. German swine plagne (vimlent variety). 

Tbeso onltiires wnre allowed to roniain in the thirtnostat nntilJune 8, at which 
time they were l«sted according ti> the method itidic<ated. 

The culture from VII had au abundant viscid growth on the surface attached to 
glaHB. Liquid turbid when slmkeu, faintly alkaline; odor di^ngreeable and charac- 
teristic of swine-plague cultures. Slight precipitate of tribromphenol ; no ludol 

The cultnre fttim VIII had a thick membrane on the nurface, somewhat viscid. 
Other characters as in procudiug caxc. Pbeuot less ahundant. No indoL 
The CTiltura from IX lilte that of Vlll. Fheuol very abundant. Very faint indol 

The cultnre of German swine plague gave nearly as much precipitate of tribrom- 
pheuol crystals as tha preceding, bnt no indol reaction. 

Varions cultures of hog-uholera bacilli t«Bted showed tlie preMnce of neither indol 
nor phenol. 

The reaaou why the indol reaction failed iu our hands is not clear. 
It may be that as the culture grows older the pheuol reaction increases 
while the indol reaction may disappear. It will be noted that phenol 
was detected in all four cnlturcK, iu the third in abundance. The crystals 
of tribromphenol examined microscopically were identical la all four 
cases. It might also be mentioned that the second culture, inoculated 
with the least virnlent swine-plague bacteria, contained the smallest 
quantity of phenol, 

BB8ISTANCK OF SWINE-PLAGt'E BAOTF.BTA TO DESTRUCTITB AGBNTS, 

Swine- plague bacteria possess less power to resist destructive agents 
than hog-cholera bacilli. Their life, even under what might be regarded 
as the most favorable conditions, is brief. In the laboratory cultures are 
liable to die out iu 3 or 4 weeks, especially when evaporation is going 
on. In bouillon but 2 or 3 days old the large majority of bacteria are 
dead, for if plate cultures be made from the liqnid only very few colo- 
nies appear where we would expect thousands. The resistance to dry- 
ing is feebler than that of hog-cholera bacilli. In the report for JSSfi, 
some esperiments are reported which show that drops from a bouillon 
cultnre dried on cover glasses failed to infect fresh tubes ou and after 3 
days. Shorter periods were not tried in this experiment. 

In another trial with perituneal exudate from a rabbit containing im- 
men»e numbers of swiue-plagne bacteria dried on cover glasses, bonillon 
tubes were infected up to the third day, but not thereafter. 



■ 91 

In the report for 18S7-'8R, p. 143, some additional expcrimPTita are 
given with Hwino-plague bacteria &om Iowa. Bacteria iu bouilloD cul- 
tures, dried for a period longer thau 36 hours, were destroyed, while 
bacteria from agar cultures lived for 6 days. The difference is very- 
likely due to the thickness of the dried film, which is much greater when 
material from agar cultures is employed, owing to the density of the 
growth. 

They are likewise more easily destroyed by disinfectants than are hog 
cholera bacilli. Hence the extended esperimenta made in connection 
with our study of hog-cholera bacilli have ma<l6 a repetition of such 
experiments with swine plague unnecessary. We simply give the fol- 
lowing experiments with lime, since this disinfectant is cheap, efficient, 
and easily applied. 

April 18, 1H9I. Five onliio oentimetreB of Ilmawater ie thoroughly mixed with a 
loop of agar growth of swine- pi ague bacteria 1 day old TroTii outLreak IX. Bouillon 
tQbea ; iDDcalated with a loop of this unitpeuBion after 45 luintiteB, 1, 'i, 'i, and 6 bonrs, 
remain clear. 

TblH experiment was repeated with the niodifi cation that two loops of agar growth 
were mixed with the limewatcT and bouilloD tubes nero iuoculated iiii mediately after 
making the mixture, and after 5, 10, 15,20,35,30, 40,50, and 60 miuntea. All but the 
Srat tube remaiucd dear. 

The limewater in a third trial was diluted with two volomea of water, and therefore 
contained but 0.04 per ceul of lime approx in lately. In this serieB all but the tube, 
inoculated Immediately after the bacteria were mixed with the limewater, remained 

These experiments show that as weak a solution of limewater as 0.04 
per cent is suJflcient to destroy swine-plague bacteria almost iaime- 
diately. 

The rajudity with which swine- plagne bacteria are destroyed by dry- 
ing and other agencies made it very probable that their life in the su- 
perficial layers of the soil where they are deposited most he very brief. 
The following simple experiments place this supposition beyond doubt, 
for tliey show that rabbits can no longer be inteeted after the liacteria 
have been in the soil for a period of 8 to 10 days. 

Match 7. 1888. A pot of sterilized soil was inoonlated by pouring npon its anrfaae 
.00 cnbio centimetrsH of a I)eef-iDrui<ion peptone eultnie which had beet) gniwing fur 
24 hours at 95° F. The pot was kept in the laboratory, covered with a dlBinfecteil 
bell jar. March 10 a rabbit was inoculated with one-fourth cnbio centimetre of 
sterile beef infnaion in which a'littlesoil had bi'eii stirred up. The ral>bit died in 48 
bonrs with nnmeroua polar-stained Bwine-plague bacteria in the iuternal orKnns. 
Ten and fourteen days respectively after the soil bad been Infected two other rabbits 
were Inoonlated from the same soil. Both remained well. 

March S9. A pot of soil was inoculated by ponring upon its surface 100 onbic centi- 
metres of a beef-infnsion peptone culture 2 days old of swine-plagne bacteria obtained 
through Prof W. H. Welch from aii outbreak studied by him in 1887 in Baltimore, 
Md. The pot was ennk into a larger pot filled with sterilized soil and the whole 
buried in the garden of the Department of Agriculture on a level with the soil. To 
test the virulenue of the onlture used to infenc the Hoil a rabbit was inoculated in the 
ear with a lauoet dipped into it. It died within 48 hours. Cover-jtlaas {irepnratioua 
calturos reveal the inoculated bacteria in tlie internal ot£B.nH, b'>i\« a.-s.^%\B.\t«, 






92 

a rabbit was inoculated from the soil as in the preceding experiment. The rabbit 
died within 2 days. No bacteria foand on co^er-glass preparations ; caltnres contain 
several kinds of bacteria. Swine- pl&gne bacteria not detected. This case was there- 
fore donbtfal. April 7, nine days after the infection of the soil, another rabbit was 
inoculated therefrom. This one remained well. 

Some experiments made in 1886 indicated a rapid destraction of swine- 
plagae bacteria in sterilized water. In 1888 and 1889 Dr. V. A. Moore 
was charged to carry out another series of experiments to test this 
problem more thoroughly. 

In the first experiment a platinum loop mbbed over the surface growth of an agar 
culture 24 hours old was stirred up in 10 cubic centimetres sterilized Potomac water 
and placed in the laboratory. A second tube of water prepared in thasame way was 
placed in the refrigerator (500-55° F.). 

From the first tube 1 cubic centimetre transferred to bouillon on the fifth day failed 
to infect it. From the second tube the same quantity failed to infect a bouillon tube 
on the seventh day. 

In a second series two tubes of water were infected, each with three loops of surface 
growth and three drops of condensation water from an agar culture. It will be 
noted that in this case some nutritive substances must have been transferred in the 
condensation water. Bouillon tubes were infected up to the thirty- fifth day from, the 
water in the laboratory. From that in the refrigerator a successful inoculation was 
made on the nineteenth day, but it failed after 38, 41, and 44 days. 

A third series was tried. Each of two tubes was infected with three loops of growth 
from an agar cnltnre 1 day old. From the one in the laboratory inoculation with 1 
cubic centimetre failed on the ninth day ; from the one in the refrigerator, after the 
twentieth day. 

Swine-plague bacteria in water containing no noarishment may thus 
succumb in 7 to 10 days at ordinary temperatures (60O-70OF.). When 
some nutritive substances are present this period may be materially 
lengthened. In lower temperatures the bacteria seem to live somewhat 
longer. A comparison between the relative vitality of hog-cholera and 
swine-plague bacteria may be tabulated as follows : 



Destroyed by moist heat at 58° C — 
Destroyed by drying (from bouillon) 

Destroyed by drying (from aj^ar) 

Destroyed in water 

Destroyed in soil 



Swine plagne. 



7 minutes 

li to 2 days . . . 
After 6 days. . 
After 10 days. 
After 4 days.. 



Hog cholera. 



15 minutes. 
7 to 9 days. 
After 4 months. 
After 2 to 4 months. 
After 2 to 3 months. 




EFFECT ON SMALL ANIMALS. 

In order to uuderst4iiid beat the pathogenic action of swiue-plagne 
bacteria a brief account of the results of iuoculatiou iuto smaller ani- 
maU will be given before the diaeaae ia swine iif discussed. These in- 
oculations being niatle with pure cultures the ejects are exhibited in a 
clearer mauner than in swine in which hog cholera is so frequently an 
associated disease. 

The various inoculations into the smaller auimalts, such as mice, rab- 
bits, guinea-pigs, pigeons, and fowls, are briefly described in connection 
with the special Outbreaks from which the bacteria were obtained. In 
the present chapter only the general results will be brought together 
and broadly outlined in their bearing on ywiiie plague. 

If we take the inoculation of rabbits as a starting ^wint we find that 
there are different degrees of virulence or pathogenic activity very 
clearly brought out. Thaa the swine- plague bacteria obtained from out- 
breaks VII and IX, and from Germany,* were of the maximum degree 
of virulence so far as rabbits are concerned, inasmuch as the latter 
died 16 to 20 hours after inoculation with very minute doses of culture 
material. The blood and the various organs contained often imuiense 
numbers of the inoculated bacteria, always exhibiting the very charac- 
teristic polar stain hIiowu in Plate xi, Fig. I. These bacteria were thus 
able to produce a rapidly fatal septicemia. 

The bacteria from some of the other outbreaks (such as I, II, IV, V, 
and YIII) were not so viruleut. The rabbits inoculated under the skin 
died from 40 hours to 7 days after inoculation. lu many such cases 
the acute septicemia was no longer present, but a peritonitis quite 
invariably appeared. In the more rapidly fatal cases this was hemor- 
rhagic; iu the others a considerable amount of grayish, sometimes quite 
viscid, exudation bad taken place. This covered the csecum, liver, and 
spleen with a thin pseudo- mem bran e, and was found to some extent 
between the coils of the large intestine. The exudate consisted of leu- 
cocytes, fibrin, aud immense numbers of bacteria. The relative pro[ior- 
tions of these elements varied according to the age of the disease, the 
leucocytes being most abnndant in the advanced stages. The swine- 
plagae bacteria were localized more or leas iu the peritoneal cavity. 
The spleen aud liver and the blood contained very few. 

■ " For eiperimeata with oultutes ol tta GBcman. ftwvne ^\a.g,Qa ao« VB- '^K'-'^'**- 



J 



94 

Theooiiraeof thedi)tease did not nlwftys correspond to this descrip- ' 
tion. lu anniall number ol' tiistaacestlie anbcutaueous inociilatioD was 
followed not by peritonitis but by pleuritisand pericarditis. Tlie exudate 
into thene uerons sacs was of the eaine nature us the i>eritoiieaI exudate 
in other cases. More rarely the pleuritis was accoiupauied by a geiiuiQe 
poeamouia of a croupous character. 

A third form of the iuocalation disease is produced by very attenu- 
ated swine-pla^ue bacteria. This atteimatinu may have been due to 
louH cuUivatiou in the laboratory or else it may have taken place in oa- 
ture. The rabbits inoculated subcutaneously may live several weeks. 
The place of inoculation becomes the starting point of a partly hemor- 
rhagic, partly purulent infiltration and thickeuing of the akin and 
aubcutjvneous connective tissue which may extend over the entire 
abdomen and thorax. The skin in places may become necrotic, dry, 
and hard. If the animal survives, which is not iufreqaeutly the case, 
the inflammation becomes circumscribed into an abscess which tiually 
heals. lu these cases internal changes such as peritonitis and pleuritis 
are absent. In some cases, however, a parenchymatous and fatty de- 
generation of the heart muscle and the kidneys is present. 

Such attenuated bacteria are still capable of producing all the vari- 
ous lesions ascribed to the more virulent varieties when injected directly 
into the circulation. This is very easily done by choosing a vein of the 
ear. After such injection we may produce a rapidly fatal septioEemia, or 
indammation of the serous membranes, according to the quautity of 
virus injected and the relative virulence. The localisation is the same 
as with subcutaneous inoculations. In rare cases even intraveuoas 
injections of small doses do not prove fatal, and tlien we may observe 
further locabzation of the virus in the joints of the estremities, chiefly 
the lower, or even in the subcutaneous and intermnscolur oounective 
tissue in different parts of the body. Such localizations were in a state 
of suppuration when they came to our notice. 

It might be maintained that the attenuated swiue-plagne bacteria, 
such as those from outbreaks YIII andX, were specifically different 
from the very virulent varieties obtained from outbreaks VII and IX, 
owing to the differences in the rabbit disease produced by them. We 
have, however, carried out experiments which dispose of this possible 
objection. By making rabbits more insusceptible to the virus of swine 
plagne by vaccination we have been able to vary the disease produced 
by virulent varieties so as to pi-oduce nearly all the forms caused by 
attenuated varieties. For example, those bacteria (IX) which produce 
a rapidly fatal septicaemia have, in vaccinated rabbits, produced a pro- 
longed disease characterized in some cases only by local reaction at the 
point of inoculation and recovery, in others by peritonitis or pleuritis 
and pneumonia. The two following cases are interesting illustrations : 

Babbit No. 19 received into an ear vein about 13 cubic centisietres 
of bouilloa culture of swine-plague bacteria, sterilized at 68° O., in five 



95 

doses at periods 3 to 1 days apart. Oa May 26, 1891, 5 days after the 
last iiijectioD, it was iuoenlated subciitaiujoiisly witli oue fivehnudredtli 
(iitbic ceutim«tre of a boiiilloD eultme of liviug swiuu-plague bacteria. 
While a cLeck rabbit (not treated) died within 30 boors after inocula- 
tiou, this rabbit died at noon June 2, i. e., 7 days after iiioealatvm. The 
Bkiu and subcutis at the point of inoeulation extuaBiveiy thickened by 
purulent infiltration. Double exudative pleuritis and pericarditis with 
lanje pneumonic regions in both lungs in which the hepatization had ad- 
vanced to the gray stage. Bits of this lung tissue esaiiiiued fresh were 
miide up chiedy of leucocytes. Swine-plague bacteria in exudate aud 
spleen. 

Two other rabbits treated with one additional injectiou of sterilized 
buuillou cultures had considerable local swelling ai'ter the test inocula- 
tion, but both recovered. 

Another set of four rabbits were treated with Bterilizod agar cultures 
suspended in bouillon.* Only one succumbed to the test inoculation 
in 6 days, while a fresh rabbit succumbed to the same inocnlatinn (one 
five-hundredth cubic centimetre bouillon culture of swine-plague bac- 
teria from outbreak IX} in 20 hours. The lesions in the vaccinated 
rabbit were extensive local subcutaneous infiltration, double purulent 
pleuritis-aud pericanlitis, and congestion of both lungs. 

The numerous bacteria in the e;(udate were not attenuated, for a rab- 
bit inoculated with a par tide from the pleural cavity died within 30 
hours. 

An eicceedingly interesting element in these results is the tendency 
of the swine-plague bacteria fuicariJA the production of disease o/ the lungs 
and serous membranesia these treated rabbits. The vaccination they have 
undergone has placed them nearer the pig as regards insusceptibility. 

A great variety of pathological conditions is thus produced by differ- 
ent degrees of viruleiice of the same species of bacteria, the significance 
of which will be appreciated when we come to the disease in swine. If 
we would arrange the various lesions according to their fatality, the sep- 
ticiemia or multiplication of bacteria in the blood stands first. Next 
come peritonitis, pleuritis, aud pericarditis with or without pneumonia, 
aud lastly Joint disease. 

The relative virulence of swine-plague bacteria from difterent sources 
thus demonstrated on rabbits has its counterpart in the reMRve viru- 
lence of the same bacteria with reference to difi'ereut species of animals- 
The susceptibility of the animals used is greatest in rabbits and gray 
mice, and diminishes in guinea-pigs, pigeons, and fowls in the order 
given. 

In guinea-pigs the lesions produced by subcutaneous inoculation 
present the various forms which we have seen characteristic of rabbits. 
There is this difference, however, that the more attenuated varieties 
are likely to have no effect on guinea-pigs beyond a slight local reaction, 

I * Sod p. 148 for details. 



J 



96 

In pigeons and fowls the inocalation disease is a septicsemia, prodaced, 
however, only by the most virulent varieties of swine-plagae bacteria. 
Attenuated varieties have no effect. 

We have seen that the bacteria from outbreaks YII and IX, and 
from Germany, all produce a rapidly fatal septicsemia in rabbits, and in 
so far no difference in their ))athogenic power is manifest. But the 
guinea-pig inoculations make a discrimination in showing that the bac- 
teria from YII are less virulent than those from IX. Inoculation with 
the latter, even in very minute doses (see p. 76), produces a rapidly 
fatal septicsemia, and hence the effect ou rabbits and guinea-pigs is 
alike. Inoculation with cultures from YII are on the other hand fatal 
to guinea-pigs only after some days, and the localizations are uncertain 
just as with attenuated swine-plague bacteria in rabbits. The inocula- 
tion of pigeons also shows this difference. Bacteria from YII are fatal 
only when the injections are made slightly into the muscular tissue. 
The bacteria from IX are fatal in 24 hours, even when a very minute 
quantity of the culture is placed under the skin. 

In case of fowls neither variety of bacteria is fatal when introduced 
under the skin. When, however, the needle punctures the pectoral 
muscle the bacteria IX prove fatal in 36 to 48 hours. With pigeons the 
case is similar. Bacteria which fail to produce any effect when placed 
under the skin may still prove fatal when injected into the muscular 
tissue. 

A further discrimination is possible in still more refractory animals, 
such as swine. It has been shown in the preceding pages that swine- 
plague bacteria from outbreak IX are the most virulent which have yet 
been encountered. One of the cultares of the German swine plague is 
still more virulent, since it proves fatal to swine after subcutaneoils in- 
oculation, while the American variety usually fails. 

The nature of the pathogenic activity of swine-plague bacteria is to 
a certain extent cleared u]) by these experimental inoculations. When 
they are capable of multiplying in the blood they produce speedy death, 
probably by the development of some poison and by a modification of 
the blood. When multiplication in the blood does not take place, the 
large seroas cavities still permit their growth on the lining membranes. 
The irritation thus set up induces a fibrinous and cellular exudation, 
which later on becomes completely cellular. The means by which the 
bacteria are destroyed in these cavities when recovery ensues is not 
known. Phagocytosis probably plays an impoi-tant rdle here, for I have 
frequently seen large numbers of bacteria imbedded in the protoplasm 
of the leucocytes. The pleural cavity is less frequently involved. This 
may, however, be due in part to the fact that in most cases the inocula- 
tions were made in the region of the abdomen or the thigh. 

The relative virulence of the varieties investigated thus varies con- 
siderably. Of those studied in detail recently the highest degree of 
virulence would belong to one form of the German swine plague. The 
others may be arranged in the following order : IX, YII, YIII and X 




THE DISEASE IN SWINE AS PBODTJCED BY THE ITJOOULATION OP 
CULTURES. 

In order to determine the effect of pure cultures swine were inoca- 
lateil under tbe skin, into tbe veins, into tbe lungs, and into the abdom- 
inal cavity. They were also fed with cultures and with the viscera 
of small aniinals which had succumbed to inoculation. The details of 
these experiments have been given under the diftereut outbreaks, and 
it now simply remains to bring the facta together. 

It ia at once apparent that any method of inoculation whatever can 
merely approximate tbe conditions prevailing in outbreaks of disease. 
Tbe bodj- receives in the one case a large number of bacteria at one 
time, while in the natural disease animals are being constantly infected 
by small quantities. A single small dose frequently repeated — and this 
is what actually takes place in an infected herd — may produce far more 
serious results than a single large dose. Again, tbe repetition of small 
doses may produce a disease quite different in character from that pro- 
duced by a single large dose of tbe virus; Anally, the ways in which 
bacteria enter the body, in the natural disease, vary greatly, and differ 
in most respects from the ways in which they are introduced experi- 
mentally. 

These and many more considerations wbieb ueetl not be discussed here, 
serve to show that with inoculations into swine we may attemjit but 
imjierfectly two objects, lirst, to demonstrate that tbe bacteria under in- 
vestigation do actually produce disease, and, second, that they may have 
a predilection for certain organs and tissues of the body where certain 
kinds of lesions are produced. 

The inoculations in swine produce practically tbe same lesions as 
those which follow the inoculations of the smaller animals. Here we 
observe variations in tbe localization of tbe injected bacteria similar to 
those produced by attenuated cultures in rabbits and guinea-pigs. 

Feeding cultures and viscera of inoculated rabbits has thus far 
proved negative. 

Subcutaneous inoculation has in most cases proved negative except- 
ing with bacteria from outbreaks I, II, and IX. Oua variety of the 
German swine-plague bacteria proved in most cases fatal after subcu- 
taneous inoculation." This, as has been stated before, gives them a 
higher potency than any American variety thus far encountered. 

Injection of cultures into the circulation is usually fatal when viru- 
lent varieties are employed. These lesions depend upon tbe time elaps- 
ing between inoculation and death, which in turn varies according to the 
virulence and the quantity of culture liquid iujected.t 

When the animals die within one or two days the visible changes are 
coniiued to the blood, and in some cases extend to the peritoneum and 
* S«e p. 93, 
^■^ t A full accaunC of these iuoculatioua U tjWeu oa '\}i\^Ba'tV-1'',i, 
H 1614 7 




plenra, which are iufiiimed ami covered with more or less exndation. 
If the autmaU live longer tliese cbniiges become more acueiitaated, and 
in aevei-ai cases portions of the luuga become bepatizod. This hepatiza- 
tion may be looked upon as seoondary to the pleiiritis, aa in case of the 
rabbits haviDg similar lesions. lu two cases the bacteria became local- 
ized in various joints of the body, where necrosis of bones and snppura- 
tion took place. Intermuscular collections of pus wore also observed. 
The duration of the disease in these cases was several weeks or longer. 
Other organs, excepting the pericardium, in one of these animals, were 
not directly affected. 

When the bacteria are injected directly into the lung tissue tbrougb 
the chest wall, death may follow within 16 to 24 hours, or life may bo 
prolonged, and severe pleuritis and pericarditis associated with hepati- 
zation of the lung tissue, may appear. Thus in pig 275 (see Plate vi) 
though the injection was made into the right lung, as a result the major 
portion of the left lung also was involved iu pucumooia. 

lu a few experimental cases the intestines were involved. In one 
case, as a result of the peritonitis following an intra-abdominal injec- 
tiou, the walls of the small intestine were swollen, inflamed, aod a 
copious, friable, yellowish exudate had formed on the deeply inflamed 
mncosa. In another case all Peyor's patches iu the small intestine were 
swollen, very hypericmic, and iu part hemorrhagic. Intense hyperasniia 
of the mucosa of the stomach has been observed in several cases, both 
after intravenous and intrathoracic inoculation. 



SWINE PLAGUE AS OBSERVED IN EPIZOOTIOS. 

The variety of lesions produced by the inoculation of swine-plague 
bacteria is by no means so great as that observed in nature. While 
there are outbreaks In which considerable uniformity is observed, there 
are others in which each animal is a surprise to the pathologist. In 
general it may be stated that the lungs and the digestive tract are the 
chief seats of the disease, though other organs, notably the lymphatic 
glands, are secondarily involved. The disease is localized iu the lungs 
and the digestive tract most likely because the bacteria gain entrance 
through the respiratory and digestive passages. 
The lungs have been found diseased in nearly every outbreak which 
s been investigated. In some (notably IV, VII, and VIII) the lung 
disease is the predominating affection and the direct cause of death. 
In IX pneumonia was absent in some cases, but pleuritis and interlob- 
ular o3dema were generally present. The localization of the disease in 
certain lobes of the lungs is quite constant. The ventral lobes are first 
attacked, next come the cephalic and azygos, and lastly the principal 
lobes. This movement of the disease seems to depeud on gravity, inas- 
much as the diseased is marked off from the liealthy portion by a nearly 
horizontal line. Iu other words, the most dependent portions of the 




9& 

I longs are tlie ones affected first, and as the disease progresses upwards 
only a small portion of the principal lobe, directly nnder the back of the 
animal, remains pervious, provided the life of the aoimal is maintained 
ap to this point. This localization of the disease is indicated on Plates 
I and II, in connection with which a description of these drawings will 

^ be found. A similar distribution of disease I have observed in cases of 
■ lioviue pneumonia dne to bacteria and to actinomyces, and in isolated 
oasQS of pneumonia in swine, the cause of which I was unable to trace 
at the time. In fa«t, in nearly all cases of pneumonia in swine, except- 
ing a few which were either caused by lung worms or duo to embolism, 
the disease involved the regions described and indicated on the plates 
by shading. lu the exceptions the pneumonia involved portions of the 
principal lobes not contiguous to the ventrals. 

Pathologists have defined two kinds of pneumonia, croupous and 
catarrhal pneumonia, or broncho-pnenmonia. In the former the vesic- 
ular portion of the lung substance ia chiefly affected; in broncho- 
pneumonia the smaller bronchioles are said to be primarily affected and 
the vesicular portion or alveoli secondarily. In croupous pneumonia, 
there is, following the stage of congestion, an emigration of red blood 
corpuscles, some leucocytes, and an exudate of fibrin into the alveoli. 
These elements are firmly matted together by the coagulating fibrin, 
making the diseased lung firm to the touch. In broncho-pneumonia 
the catarrhal condition of the smaller air tubes makes them impervious 
to air. The lung tissue which they supply is gradually emptied of air 
and assumes the appearance of red flesh, owing to the collapse of the 
walls of the alveoli and the distended condition of the capillary net- 
work. Subsequently the inflammation extends into the alveoli, which 
then become distended with cellular masses. 

The definitions of pathology do not always apply t» classification of 
lesions from the standpoint of etiology or causation. A definition from 
an anatomical standpoint refers to a condition. The same bacteria may 
nnderdifferentcircumstancesproduceavariety of conditions. Another 
difficulty meets us in attempting to describe the lesions due to bacteria 
in animal organisms. The definitions have had their origin in human 
diseases and are not always applicable to animal diseases. Moreover 
there is a diflference between difl"erent species of animals. Anyone who 
has experimented with different animals knows that they do not react 
exactly alike after inoculation with the same bacteria. There seem to 
be certain peculiarities belonging to each species which have not yet 
been clearly formulated by comparative pathology. They may be due 
to differences in anatomical structure or to physiological peculiarities. 

It is furthermore evident that the nature of the luug disease will de- 
pend more or less upon the mode of entrance of the virns. If it can 
enter only by way of the air tubes it will appear [)erhaps as a broncho- 
pneumonia. If it can enter the lung tissue through the circulation we 
I may have more or less scattered centers of liopatiKatlon (eia'a'iVSs. -^wBiXi.- 



J 



1 



monia). If it can enter by way of the pleura, the vims will creep aloo^ 
the interlobular atkd periliroiicbial tissue before it invades the pareu- 
cbyms proper. 

In natural infection the swine-plagne baoteria enter the laag tissue 
chiefly by way of the air tubes. At the same time it is not improbable 
that oocaaiouatly they may enter the serous cavities first, i.e., invade 
tbe pleural cavities and thence the lungs. This probability is shown 
by our inoculations in which intravenons injections produced exudative 
plenritis, and pneumonia of the most dependent portions of the Inngs 
covered by the pleural exudate. It is not improbable that even in tbe 
natural disease the bacteria which have gained access to a portion of 
the luug tissue by way of the air tubes reach the pleura covering this 
portion, and may then by th is route invade other portions of the lungs. 
It may be that in this way a pneumonia originally single may become 
double. I have also observed not infrequently that the first pneumonio 
inflltratiou of thepriucipal lobe was at the points of contact with the 
diseased ventral lobe, and that the resting of a lobe against an inflamed 
serous surface, such as the pericardium, caused a pneumonic infiltration 
at the point of contact. 

These facts go far to show that swine-plague bacteria may invade 
the luugs both from the air tubes and the pleural cavities. I am not 
inclined to believe that pneumonia is produced to any extent by swine- 
plague bacteria actiug as emboli in the circulation, because they are 
rarely found in the blood. Comparative inoculation experimeuts in rab- 
bits show that the chief indication of attenuation is inability to multi- 
ply in the blood. This probably holds with equal force in awine whose 
power of resistance is so much greater than that of rabbits. 

Wo may, therefore, expect t« find the character and seat of the lung 
lesions somewhat varia bl&^and this is actually the case. It would be 
difficult to find two lungs exactly alike so far as gross appearauces go. 
This to be sure may be due largely to the fact that animals die in dif- 
ferent stages of the disease. Yet there are differences evidently~not 
dependent on this fact which must be left for special pathological in- 
vestigation. 

After these preliminary remarks we turn to a brief description of a 
swine-plague Inng. In general the cephalic (anterior) half is hepatized, 
of a dark-red or grayish-red color, firm to the touch. The pleura is more 
or less thicltened and opaque, andcovereil with easily removable friable 
false membranes. In the more recently aflectcd regions a faint but 
quite regular delicate mottling with yellow is observed to shine through 
pleura when not thickened. These minute, hazy, yellowish dots 
usually occur ia groups of four. Occasionally whitish or yellowish 
patches varying much in size are seen perhaps more frequently in the 
ventral lobes. These correspoud to homogeneous dead masses of lung 
issue. 

When such lungs are cut into, the section presents much the same 






appearance, botli as regards color, mottiing, etc., as when viewed from 
tlie surface, excepting tbat the details am leas distiuct. In some cases 
in the most recently iuvaded territories in the principal lobe and nearer 
the dorsum in the other lobes, the dark or grayish-red cut surface shows 
grayish lines usually arranged in curves and circles. These, so faras I 
could determine, represent the cut outlines of the interlobular and peri- 
bronchial tissue infiltrated with cells. It has already been stated that 
these lines may represent the paths along which the swine-plague bac- 
teria invatle the lungs from the pleural surface. 

The cut ends of the brouchi of the ventral lobes are frequently oc- 
cluded with thick, whitish pus; in the other lobes a reddish froth is 
usually present. Barely they also contaiu thick glairy mucus in which 
particles of dry pus and lung worms are imbedded. The contents of 
the air tubes in the ventral lobes may have been derived from the over- 
disteuded alveoli, or else a broucho-pneumonia, may have preceded the 
swine-plague pneumonia, 

In microscopic sections of diseased lung tissue the alveoli and small- 
est air tubes are found distended with cell masses consisting chiefly of 
leucocytes. I have seen very little fibrin and very few red corpuscles in 
the alveoli, even in cases iu which the disease was quite recent. It may 
be that the stage represented in ordinary croupous pneumonia by the 
presence of fibrin iu connection with the cellular elements is very brief, 
and that it is speedily replaced by large numbers of leucocytes. The 
large predominance of these elements iu some portions of the lungs, as 
well as beginning fatty degeneration, is probably the cause of the reg- 
ular mottling of the liiugs, as seen from the surface and above referred 
to. (See Plate ix. Fig, 2,) The little yellowish haiiy dots represent 
the filled and distended alveoli surrounded by the hypersmic walls. 

The necrotic and caseous changes so frequent in swine plague deserve 
brief attention. The caseous changes were particularly noteworthy iu 
outbreak IV (Plates vii and viii, Fig. 1} and necrotic foci especially 
abundant in outbreak VII. (See Plate v.) The latter are usually 
quite small and disseminated in large numbers over the diseased lobes. 
The former represent larger masses from a marble to a horse-chestnut 
n size. There is need for a distinction between these two forms of 
lecrosis, as I regard them as due to difi'erent processes. 

The necrotic masses represent tissue which has been destroyed by 
;he rapid multiplication of swine-plague bacteria iu particular locali- 
Hence they are found iu all stages of the pneumonia. The large 
caseous masses may be considered as the result of a slow death of 
larger territories of lung tissue, due primarily to the gradual overdis- 
tension of the tissue by leucocytes, and hence the gradual catting off 
of the blood supply. One is a rapid death due directly to highly viru- 
lent bacteria, the other a slow death, or iu other words a kind of dry sup- 
puration in the later stages of the pneumonia, characte^\e,i\t o^ ■<!»», ■^'«^> 

id due indirectly to the irritation •? yoi^iai^s wio^fe ^-^.Veo.Ma.ViA ■E*»y«'* 
bacteria 





102 

It has already beeu remarked tbat different species of animals react 
somewhat differently to intlamtiiiitory agents, and the tendency towards 
caKeation in the luiigs of swine is, I thiulc, au illustration of the hind of 
reaction manifested by swine as a species. When irritating substances 
or enltnres of bacteria are injected nnder the skin of pigs, there is a 
tendency to tlie formation of a rather firm tnmor-like swelling. This 
tumor at first consists of a rather tough, yellowish -white mass, and 
only after a time softens in the center into a thick, tiemi-liquid pas re- 
sembling flour paste. This tendency to a firm, dry infiltration of pus is 
likewise observed in the sometimes quite extensive button-like necroses 
or " ulcers" in the larlte intestine. The same may be said of the large 
homogeneous cheesy masses into which the diseased lung tissue is con- 
Terted after a time. (See Plate vii.) 

It is not to be understood from the preceding that the pneumonia 
spreads from a single lobe, such as the ventral, in all or most cases. 
The case on page Gd(No. 3Sd) is asignal illustration of the contrary. In 
this every lobe contained some necrotic foci which were evidently due 
to a deposit of swine plague bacteria in these separate localities, and 
which had not yet coalesced by an extension of the disease when the 
animal succnmbcd. 

The inGammation of the pleura frequently extends to the pericardium. 
(See Plate x.) This membrane is opaque, thickened, and its vessels 
distended. It may be glned to the contignons lobes of the lungs and 
covered with exudate. Less frequently it is adherent to the surface of 
thfl heart, which is then covered by a false membrane, smooth or 
roughened, extending upon the large vessels emerging at its base. 

DISEASE OF THE DIGESTITE TRACT IM SWINE PLAGUE. 

In order to elucidate this important subject we may briefly refer first 
to the results of inoculation, second to those cases of natural swine 
plague from which hog-cholera bacteria can be safely excluded. 

In a considerable proportion of those auimals which were inoculated 
with Bwine-plague cultures a severe catarrhal inflammation of the lin- 
ing membrane of the stomach was produced. The hyperaimia was 
very intense, bordeiing- on hemorrhage. Again, in another case the ex- 
tension of the peritonitis, produced by intra-abdominal inoculation, 
along the mesentery caused a severe inflammation with exudation on the 
mucosa of the small intestine. In one case all I'eyei''8 patches of the 
small intestine were in a hyperaimic, partly hemorrhagic condition. 

In outbreak "VIII there was observed in 3 out of 5 cases more or less 
extensive hyperiemia of the mucosa of the large intestine bordering on 
a hemorrhagic condition. In the case (No. 385) caused by infection 
from outbreak IX, the inflammatory condition of the large intestine 
was a prominent lesion. In these cases hog-cholera bacilli may be ex- 
cluded with reasonable certainty. In the earlier cases of outbreak IV 
laJiar croapoas exndation appeared, wh\a\i I ha-ya eoaaidered and 




103 

still regard as the effect of swiDe-pIagne bacteria id tbe large ititestiDe. 
(See Plate vin, Fig. 3.) Of tliiB lesion more or less has been said on page 
34,in conuection wilL abrief reviewof tbeontbreat. It will bereinem- 
-bered that in this epizootic hog-cholera baeilli were fonnd in the later 
oases, while swine-plague bacteria were present in a large proportion of 
both earlier and later cases. The croupous iuflauimatiou in this out- 
break differed markedly from the necrotic and diphlheritic iuflamniation 
cau sed by hog cholera bacilli. At tbe same time we must regard it as 
UDsatisfnctory in the present state of knowledge to reason from the 
pathology of swine disease to its etiology. 

In the remaining outbreaks two classes appeal^ those in which both 
swine plague and hog-cholera bacilli were readily detected (11, V, VII), 
and those in which hogcholera bacilli were not fonnd, or in which their 
relation to the disease was highly doubtful (I, VI, IS). In most of 
these ontbreaka the intestines were diseased, and tbe lesions resem- 
bled in general those found in hog-cholera epizootics. While there 
can be DO reasonable hesitation in attributing tbe intestinal lesions 
largely to hog-cholera bacilli when they are detected, it is difficult to 
understand those cases in which hog-cholera bacilli are not fonnd, or in 
which such attenuated forms are met with occasionally, the power of 
which to cause disease is highly question able. 

It is reasonable to assume, at least nntit more knowledge is at hand, 
that, even in those cases in which hog-cholera bacilli are not detected 
in the internal organs and yet extensive necrosis and ulceration of the 
large intestine is present, these lesions are due to hog-cholera bacilli or 
bacteria not yet recognized. The difficulty of esamining the intestines 
for pathogenic bacteria and the amount of labor involved is very great, 
and hence for want of time and snfticient assistance this part of the 
work has been set aside in these investigations and the attention cen- 
tered on the lunga and the other internal organs. It is apparent that 
even if certain bacteria are found in the contents of the digestive tract 
their relation to disease processes going on there is by no means proved, 
since the intestines contain a large variety of bacteria at all times. It 
is necessary to demonstrate that with pure cultures of such bacteria the 
same, or a very similar intestinal disease, can be produced. While this 
demonstration has frequently been made by ns with virulent bog-cholera 
bacilli, which are also quite invariably present in the spleen, snch dem- 
onstrations fail with swine-plagne bacteria and with very attenuated 
hog-cholera bacilli, aud we are at a loss to determine how much disease- 
producing power to attribute to them. 

The production of intestinal disease by swine-plague bacteria may be 
supposed to go on as follows: The bacteria first attack the lung tissue 
and there produce more or less hepatization. The blood Ands its path 
through the lungs partly obstructed. This reacts on the blood in the 
right side of the heart and the venous blood entering it. Hence there 

L Biay be more or less stasis of blood in the \wcta.\ c\\*ivi\^'Ov«\i ■^\v.^Si\». 

Ktarn impairs the digestive functiona oS ttie aVoraa-aV 'Y\ifes«\a»->^'*S>* 




I 



bacteria in the langs in the later stages of the pneumonia may lie 
cotigtied u]) in tlie contents of tbe bronchial tubes, swallowed and passed 
tbrongb the impaired stomach uuhanued into the intestines. The stagna- 
tion of feces in the large intestine furnishes the bacteria an opportnnity 
to cause inflammation of the mncous membrane and exudation. The 
tendency of swine-plague bact«ria to cansti Bbrinous inflammatory de- 
posits on serous membranes may servo to explaiu such action on macous 
membranes. 

If we continue to follow the results of snch jiossible localiziition we 
must assume that in the diseased intestine a considerable multiplication 
of swine-plague bacteria takes place, which, discharged with the feces, 
put into the surroundings of the swine a large number of pathogenic bac- 
teria. These swallowed by healthy pigs may lead directly to intestinal 
disease without any necessarily extensive lung lesions. The virus thus 
multiplied by the multiplication of cases will produce a more and more 
virulent epizootic in which intestinal lesions may predominate. While 
there is no proof that these phenomena actually take place, all the facts 
observed iu an outbreak readily accord with such a hypothesis. 

The mingling of two diseases, hog cholera and swine plagne," makes 
it necessary to compare briefly the pathogenic power of the bacteria 
causing these diseases. This mingling has greatly complicated our 
understanding of the extent and the kind of lesions attributable to each 
bacterium. Thus, in hog cholera, the chief force of the disease is spent 
upon the digestive tract. The lungs are frequently involved in collapse 
and broncho-pneumonia of limited extent, but collapse seems to be not 
uncommon in apparently healthy pigs, and broncho-pneumonia may be 
conceived of as developing from collapse without the necessary interven- 
tion of disease germs. Again, the presence of lung worms may account 
for much of the localized brouchitis and hepatization. It is easy to 
nuderstand that hog-cholera bacilli accidentally present in the blood in 
disease may pass through a healthy lung without iiijary, while lungs 
affected with collapse and lesions due to lung worms may offer a favor- 
able opportunity for the lodgment of emboli containing bacilli. The 
disease process thus starting up may be continued by sputum bacteria 
(resembling or identical with swine plagne). It becomes difiBcult there- 
fore to determine whether hog-cholcra bacilli have any speoihc eflect 
on the lungs. 

In swine-plague the exact reverse is true. The predilection of swiue- 
plague bacteria for the lungs is a demonstrated fact even with small 
experimental animals. Their exact effect on the mucous membranes of 
the caecum is not easily determiuable owing to the frequent association 
with hog-cholera lesions. That they produce a diffuse intense inflam- 
mation, associated at times with fibrinous exudation, will not, I think, 
be denied in view of the facts brought out in the experimental part of 
this report, 

* See ako p. 338 for Home pcaotic*! obaervaUons on ttu aubjsot. 



105 

We liavo tLu8 in liog cholera primary disease of tlio intestines with 
tierbaps secondary localizations in tlie lungs; in swine plague primary 
disease of the lungs with secondary infection of the intestines. 

The pathological action of these two kinds of 1)acteria can not be for- 
mulated with any precision without extended invest! gatious directed to 
that subject alone. Meanwhile a few broad facts can be deduced from 
the inocnlation experiments. Hog-cholera bacilli multiply in clumps 
in the capillaries of the parenchyma of the various organs, where they 
primarily obstruct the circulation, and thns produce necrosis of tissue 
in their immediate vicinity. When this takes place in the folltcnlar 
apparatus of the intestine (in rabbits) necrosis of portions of the mucous 
membrane, followed by ulceration, may ensue. They do not produce 
fibrinous and cellular exudation on serous membranes, and probably do 
uot multiply on these membranes. Secondarily, they produce paren- 
chymatous degeneration of the liver, kidneys, and heart-muscle, which 
degeneration may be due to the toxic bodies formed by them. 

Swine-plagne bacteria, on the other hand, seem to multiply difl'usely 
and abundantly wherever such multiplication takes place. When in 
the blood death is exceedingly rapid; when in the large serous cavities, 
exudates are quickly produced and death may ensue in from 3 to 7 days; 
when under the skin necrosis and suppuration take plac^. 

The following table gives briefly the important ditt'erejices observed 
between bog-cholera and swine-plague bacteria. Those features com- 
- juon to both are omitted ; 



MorphoJoi/iea}. 

1, Aboatl/zloug and 0,5 toO.li^ vide in 
(coveT'glasa preparatioDB moauted 
In lialBdm). 

|i They show tlie so-culled polar stain 
n oertaiii conditions. 

(, Nod -mo tile. 



ti Giowtli in bouillon feeble. 

I. Growtli ou gelatine feeble or absent. 

Ii Growth on potiito fails. 

'i Tends to produce acidTeaotion of onl- 

tiire liquid, 
t Prodnces no fermentation of glncose. 

i ProddCRB phenol and indol (!). 
t Rapidly destroyed in water, in soil, 
by drying.' 



1, Ahoiit l.a to l.S 



a. No characteristic polar stain, "flie 
central part of rod fiei^ueutly less 
stained than periphery. 

3. Motile (posaess Hagella). 

Bioloyieat. 

4. Tn bonillon moderate. 

5. Ou gelatine moreTigoroaathanswine 

plague. 

6. On potato nsnully abundant. 

7. Tends to produce alkaline roaotiou. 

S. Causes fermentation of glncose with 

production of COi and H, 
9. Produces neither phenol uor indol. 
10. Quite resistant to the same agents.* 



* See page 92 fov \ia\i\o. 




106 



PatluigmHe. 



11. Hnltlpliea difTuBelr in blood or on 
j membranes. 

12. Produces Bapticatmia; fibrhionB and 
cellnlar infl animation of aatoiie 

inbranes andpneumouiB in Bniall 
animals. 



13. Most virnlent varieties are fatal to 
mice, rabbitfl, giiiae.vpiK8, and pi- 
geonxin very minute doses,* Deatb 
in 16 to ^ hours. 



. Multiplioi 



11 blood V 



n dumps. 



12. Does not produce inflammiLtioti of 
serous membraues. Produccia pa- 
runcliymatuns degonuration of vital 
organs. Nooroses in liver. More 
attenuated varieties caiiae infiltra- 
tion and uli>erBtion of Peyer's 
pstehes and iufiltratioD of lymph 
glands. 

VS. Most virulent varieties are fatal to 
mice, rabbits, and guinea-pigs in 
minute doses." Death in 5 to S 



I 



In view of tUe mJDgling of these two diseases can we by inocnlation 
of both bacteria at the same time gain any information a3 to their rela- 
tive activity ? If both kinds of bacteria were of unchanging virulence 
this might be done, but we may have in natural outbreaks attenuated 
Bwioe plague associated with virulent hogcholera bacteria and the re- 
verse. Or one kind of bacteria may invatle the animal after the other 
has spent its energy. The variety of combinations which may occur in 
nature is too great to be imitated by experiment. 

It was, nevertheless, desirable to see what effect the inocnlation of 
mixed cultures might have. Hence the following experiment was tried, 
the result of which, though very important, is not conclusive. 

May 12, IBEIl. Cultures of swine plague from ontbreak IX and of bog cholera from 
a Virginia epizootic, botb tbe most virulent in the laboratory, were cbosen. From 
the growth on an agar culture of these swine- plague bacteria 24 boars old a tarbld 
euspensiou in bouillon was prepared. A bouillon culture of Ifae hog-cholera bacilli 
only 24 honi-B old in vrbich the growth waa nbundaat was also ou baud. With these 
cultures three pigs, about 6^ months old, of the same breed and lot, wore inocnlAted 
as follows : 

No. 462 received ioto the right lung one-fourth cubio centimetre of the swlne- 
plague suspension, and tfatee-fonrtba cubic centimetre of the hog-cholera boailloo 

No. 463, inoculate<l in the same way with twice this quantity, t. s., one-half cubic 
oentimetie swine-plagne and 1^ cubic centimetre bog-cholera cnltnre. 

No. 461 received 5 cubic centimetres of tbe hog- cholera cnltore alone into the right 
lung. 

No. 4fi3 was dead next morning, within 16 hours after inoculation. Animalin good 
condition ; weight 72 pounds. Subcutaneous fat reddened. Blood oozes from the 
cut vessels and coagulates feebly. Arborescent iojectjoii. of minute bloodvessels 
of connective tissue in axilla and between muscles on thorax. In abdominal cavity 
a considerable quantity of yellowish serum. Ventral portion of spleen imbedded 
in an elastic whitish exudate. Costal and diaphragmatic plenra show intense 
vaaonlar injection. In right pleural sac about 140 cubic centimetres blood-stained 



* It must be borne in mind that the vario 
plague bacteria can not be individoatly con 
effect in a tabulated form ; we must refer ti 



B attenuatiouB of hog-cholera and swino- 
idered with reforeiioe to their pathogenic 
the text for these. 



liquid, ill left 70 cabio ceoti metres. Lungs but partly collapsed ; isitematoDB. Over 
the entire riglit lung u very thia friable osudate; over tbe left tbia is faiind oiilj 
ou most <le[)BU<lBiit piirtinn. Eiglit tuug punctured by uoedle iu pttuci pal lobe. The 
panctnre shows us s hemorrbagic spot. 

In the sl.oinaoh — wliioh ia filled w th f 1— a d in intestines, nothing abnormal. 
Kidneys nith baae of pyramids da L ed Spl lightly enlarged. 

In the spleen pulp only swine-pI ba te d tected. Iu an agar culture there- 

from no motile bacilli seen. A ^ 11 It fr m tbe peritoneal exudate contains 

only siviua-plague bacteria. Cov glass p pa at ons from both pleural and perito- 
neal e\adate shorn numerous pola t d ba te a. 

No. 4ri2 manifested labored br ath g after the inoculation. It lay oli its 

bedding unable t« gel up. It was found dead May IC. 

Considerable reddening of the skin on ventral aspect of body. Subcutis as in 463. 
In abdominal cavity a small quantity of yelloivish serum and some iibriuons coagnla. 
Spleen quite large, congested and friable. 

Thoracic cavity. Bight pleoral sac contains 100 cubic .centimetres of turbid dark 
reil fluid. Cousiderahle friable exudate covering cuittal and pulmonary pleura of this 
side, especially abundant on small lobes. Pleura opaque, thickened and -wrinkled. 
Both cephalic and ventral lobes not enlarged, but firm, on section grayish red, solid. 
Bronohloles filled with whitish muco-pus. The needle puncture in principal lobe ia 
tbe center of a hepatized mass, fully 2 inches in diameter; on section some lobnlea 
bright red, others hemorrhagic, dark red. Nearer periphery of this mass the hepa- 
tization is grayish red ; the interlobular and peribronchial (issue appear as irregular 
grayidh lines. Iu the left lung the principal lobe congested; slight interlobular 
oedema. Along cephalic border, under pleura, a dark red hepatized mass, about one- 
half inch iu diameter. Tip of ventral lobe adherent to pericardium, bouiiath udhe- 
sious small foci of dark red hepatization. In terminal bronchi adult lung worms. 

Pericardium adheres to heart surface by means of a thick yellowish psendo-mem- 
hraue. Olauds along posterior aorta hemorrhagic. 

Digestive tract : Stomach empty. Mucosa thrown into folds and covered with an 
abundance of very viscid mucus. In fundus it is congested. Hyperiemia also around 
cardiac expansion. Duodenum pigmented. Mucosa of ileum swollen and sprinkled 
with small hemorrhagic spots. Mucosa of ciecum and upper colon discolored. In 
lower colon minute whitish spots, with iujected margin, evidently auperflcial ulcers. 
Meso-colic glands enlarged, ]iyper»mio. 

Liver somewhat enlarged, quite firm. Acini slightly projecting; some dark red; 
in most of tbem intralobular necrotic massesj the result of some former disease.* 
Portal glands enlarged and hyperffimio. Kidneys congested; pyramids dark bluish 
red. Glomernli just visible to naked eye as injected points. 

Bacteriological eiamination : Iu cover-glass preparations from the hepatized moss 
of right principal lobe very many awine-plogue bacteria and a few somewhat larger 
forma. In two agar plates from the same region large number of colonies of two kinds 
appear. One reprosouts swino-plague about ten times more numerous than the hog- 
obolera colonies, which are ou second day twice as large. In covor-glaas prepara- 
tions of spleen pulp a considerable number of bacteria appearing as hog -cholera 
bacilli. Tbe same is true of the liver. Agar plates front each organ contain only 
colonies of hog- cholera bacilli. 

No. 4lil, though aick for a few days, fully recovered. 

This experiioeut illustrates tbe greater rapidity of action of swine- 
plague bacteria even in small doses. It also demoustrates their greater 
virulence, for the pig inoculated with a large dose of hog-cholera bacilli 



IL 



108 

alone, although sick for a few days, recovered. Another fact of im- 
portance illustrated in these cases is the slow action of hog-cholera 
bacilli in invading other organs. Thus the swine-plague bacteria had 
killed Ko. 463 before the hogcholera bacilli had invaded the spleen 
and liver. In No. 462, however, enough time had elapsed to permit the 
hog-cholera bacilli to spread through the body while the swine-plague 
bacteria were now limited to the lungs. The invasive power of hog- 
cholera bacilli, though slower, is nevertheless more lasting. 

There is no evidence to support the view that either swine-plague or 
hog-cholera bacilli may produce serious disease in man. 'So bacteria 
have thus far been described as the cause of human disease which are 
identical with either of the bacteria of swine disease. Nevertheless 
the possibility of an occasional transmission from animal to man can not 
be wholly set aside until more thorough bacteriological investigations 
of human diseases shall have been made in those localities where infec- 
tious swine diseases are very prevalent. 

It is of interest to note that among human diseases typhoid fever 
bears a close resemblance to hog cholera, not only as regards the gen- 
eral character of the specific bacteria, but also with reference to the 
disease itself. Again the diplococcus of croupous pneumonia in man 
has many points of likeness with swine-plagae bacteria. The general 
pathological effect as well as the tendency to produce various forms of 
disease by localizations, such as pleuritis, pericarditis, meningitis, are 
strikingly similar to the miscellaneous lesions caused by swine plague 
bacteria. Typhoid fever and pneumonia are not infrequently associated 
in man, thas affording another point of similarity to the frequently asso- 
ciated swine diseases. Another pecaliarity which is common to the 
pneumonia bacteria in man and to those of swine-plague is their frequent 
occurrence in the mouth and upper air-passages of man on the one hand, 
of swine on the other.* 

* See the following chapter and appendix. 




ATTESUATED SWISE-PLAGOE BACTERIA IN SPOKADIC CASES OF PSEPIOMA AND 

IN SEPTIC II!SL\SES DF SWINE, ASD IN THE UPPER AIR PASSAGES OF 

nEALTIIV SWINE ANR OTHER DOMESTICATED ANIMALS* 

Piiring the iiivestigatioos of the epiKoJitic forma of swine plagne 
desoribed in these pages, bacteria not rtistingoishable from those of 
this disease were occasionally enconntered in sporadic cases of pneu- 
monia. The affected swine were usually those which had beeix exposed 
to hog cholera or swine plague, or mixed outbreaks, or Lad beeu inocu- 
lated and had survived. They were kept isolated for a time by them- 
Belvesorwithothercasesof similar history, and they generally died after 
fiome mouths or became so unthrifty that they were killed. Occasion- 
ally they died with some iuflammation of the serous membranes, such 
as peritonitis, periuarditis, or pleuritis. In such cases when examined 
swine plague bacteria were as a rule detected. These lesions were 
attributed to injuries which the swine, piiuued together, inflicted upoxi 
one another by fighting. If we bear in mind the variety of lesions 
which may be produced by swiue plague bacteria when inoculated into 
healthy swine (pneumonia, plenritia, pericarditis, peritonitis, inflamma. 
tion, and suppuration of the joints, inflammation with exudation in the 
intestines), we need not be surprised to encounter them in similar 
affections arising under the usual conditions. 

The sporadic cases of pneumonia were puzzling in so far as it was 
difficult to account for the presence of swine-plague bacteria. These, 
as we have shown, very easily perish by drying, and when in water and 
in media unsuitable for their development. How they can survive for 
weeks and mouths in the surroundings of swine is iuesplicable. To 
liud some other explanation I was led to examine the respiratory tract 
of apparently healthy pigs to see if here, in a manner analogous to 
the bacteria of pneumonia in man, they survived and became a poten- 
tial source of infection under certain conditions. The result was posi- 
tive in many cases. Swiue-plague bacteria or bacteria not distinguish- 
able from them were found in the nose, at the base of the tongue and la 
^tbe larynx of a certain number of healthy swine. 

* In tUis chapter no effort has been made to give an LieUtrical review of tboae 
BSperimeuta made \>y futCDor obaervere wliioli demonstrated the occasiouai virulence 
of the saliva of lunn and aiiimala. The general rclationehip of tboiip Luefcnn from 
various domeBtioated animals to swine plagne bacteria is, 1 tliiiik, brought out for 
the firab time in these pages. See also appendix to this report. 




110 



The cases which have come nnder our observation may be gronped 
into several classes : 
1. Sporadic pneumonia. 
3. Other a&ections, chiefly inflammatioua of serous membranes. 

3. Older aiiimaU having passed through diseases but apparently 
healthy. 

4. Younger animals not known to have heen exiiosed to disease. 

5. Animals entirely free from these bacteria. 

Groups 1, 2, and 3 generally include, in our observations, older ani- 
mals. 

The method used in all cases was the subcutaneous inoculation of 
rabbits with the tissue, secretion, or exudate anspectedof carrying these 
bacteria. The inoculations were made in part coujoiutly with Veterina- 
rian F. L. Kilhorne; in part by him alone. Great care was taken to 
prevent infection from esterual sources. At first only the nasal secre- 
tion was used. This was drawn up with a sterile pipette and then in- 
troduced into the snbcutis of the rabbit through a small incision in 
the skin. This method did not seem quite satisfactory, and in a num- 
ber of cases the animal was killed by bleeding, the mouth carefully 
exposed from below and mucus collected from the base of the tongue, 
the posterior uares, epiglottis, and from beneath the vocal cords. The 
mucus was placed in a sterile watch glass. The skin of the rabbit was 
freed from hair and thoroughly washed with a solution of mercuric 
chloride 1:500; with Samed scissors, the skin was cut through usually 
on the side of the abdomen, a little pocket formed, and a drop of mu- 
cus put into it with flamed forceps. The incision was either left to 
itself or united with a stitch of sterilized silk. 

These precautious thus prevented any external infection. At the 
same time a prolonged experience in such work leads me to believe that 
Bwiue-plague bacteria are not transmitted in added condition, excepting, 
perhaps, for a few days only^ The outcome of the inoculations also in- 
clined us to exclude any accidental infection. When several rabbits 
were inoculated with mucus from the same locality they either died 
together or both survived. 

The demonstration of swine-plagne bacteria in the upper air passages 
of swine naturally ted to an examination of the air passages of other 
domesticated animals by the same methods. These are reported by 
Dr. V. A. Moore, assistant in the laboratory, to whom this part of the 
work was intrusted. It will be seen from this report that an attenuated 
variety of bacteria, belonging to the group of swine- plague bacteria and 
not distinguishable from them, iuhabitihe mouth and upper air passages 
of such domesticated animals as cattle, dogs, and cats, and that some 
sporadic diseases among smaller animals, such as rabbits, guiuea-jjigs, 
and fowls, are caused by the same bacteria. This group has a wide 
distribution, therefore, aud may be regarded as a more or less common 
inhabitant of the mucous membranes. 




In tLe following brief synopsis of tlie cases illustrative of the above 
BtatemeDts, they are groaiied as nearly as posaible in accordance with 
the classification above ontlined: 

1. Sporadic pneamonia.— Pig No. 481. Planed in infected hog-cliolera pen January 
11, lS8d. Since February 1, large sores are observed on the sLonldorH, attributed to 
bites inflioted b; other awine id the pea. It died March 5, very much emaciated. 
In the ciBCum several cratat-like ulcerations, iuyolving the muscnlar coats. Iq the 
upper colon about a dozen ulcers, one-fourth to thtoe-eighths ioch iu diaoietei. 

TLe ventral and cephalic lobes of both lungs and the roots of priacipal lobes, also 
foci iu uodian lobe, hepatized, pale red. 

A bit of diseased luug tiaaue torn up in sterile bouillon and one-fonrth cnbio centi- 
metre injected into a rabbit. It died iu 40 hours, with exudative peritonitis, due to 
Bwine-plague bacteria. 

In this case these bacteria may have come from the other animals in the infected 
pen. In the following case the sourco is not so obvious. 

No. 492, received at the Station January 25, 1888, with throe others (■100-193, iu- 
claaivo). In making inoculations from the nasal m liens of these pigs, to be described 
later. Dr. Kilborae noticed that the secretion was muco-purutent, while in other pigs 
handled at the same time it was serous. No. 492 became unthrifty, and died aboat a 
month after it was brought to the Station. 

The lungs were firmly bound to diaphragm and chest wall by old adhesions, The 
ventral and cephalic lobes, the roots of the principal lobes of both Inngs and the me- 
dian lobe airless, in condition of broncho-pneumonia. The catarrhal masses in 
the alveoli appeared as a pale grayish yellow, delicate mottling undortbe pleora. 
Throughout the bepatized portions are yellowish necrotic foci one-sixteenth to one- 
eighth inch in diameter. The smaller bronchi contain a soft, oreamy muco-pus. In 
the large bronchi, the mucosa hyperiemio. Bronchial glands enlarged, very palo 
and Arm. 

Two rabbits inoculated as in prece diug case. One died in 40 hours, the other on 
the third day. Bacteria showing the polar stain present in. largo nnmbers in organs 
of the first ; in small numbers in the second rabbit. In cultures they are not distin- 
gnishable from awine-plague bacteria. 

Pig No. 267, received October 16, 1889. This animal belonged to a lot of swine 
which had been inoculated with attenuated hog-cbolera cultures and subsequently 
exposed to hog cholera. The animal died January 2, 1890. In the lunga were regions 
of collapse and broucbo~pneumonia, as well as marked bronchitis. From the abun- 
dant mncns in the upper trachea two rabbits were inoculated. They succumbed on 
the fourth and the sixth days, reapectively, to an exndative and hemorrhagic peritoni- 
tis characterized by the presence of swiue-plague bacteria. 

-Fig No. 188. This animal was placed in an infected hog-cholera pen Match 13,1889, 
and removed in 5 days. It was killed December 9, after a long period of antbrifti- 
neaa. The ventral lobes of both lungs were bepatized, of a grayish-red appearance 
(broil cbo-pneumon la), The liver covered with bluish and whitish patches, in which 
the interlobular tissue is thickened. This tbickeniug is limited to the surface. One 
rabbit inoculated with mucus from larynx died in 10 days, with extensive sabcutane- 
ous purulent infiltration and es:udative peritonitis. The only bacteria found were 
tbe Bwine-plague bacteria. 

Pig No. 308 was purchased from a neighboring farm February 7. Four days later 
it was killed and hepatization of a portion of both prinicipal lobes determined, to- 
gether with bropchilie of tbe air tubes leading to these diseased regions. Two rab- 
bits were inoculated &om the tracheal and pharyngeal mnoua, and one from the 
bepatized lung. The latter remained alive, while the two former died iu 3 and 4 days, 
respectively, with extensive exudative peritonitis. The swiue plague bacteria alone 
present in the organs of both rabbll-s. 






112 

Pi|i; No. 119 was placed in an infected hojr-cholera pen January 22, 1889, where the 
swine-plagae disease was present. September 2 it was transferred to another pen, 
and killed Jaunary 13, 1890. The internal organs were healthy, with the exception 
of the lungs, in which there were several small foci of collapse and some lung worms. 
One rabbit inoculated with nasal mucus from the base of the tongue died in 3 days. 
There was considerable phlegmonous inflammation and peritonitis as the result of the 
inoculation. The peritoneal exudate contained immense numbers of swine-plagne 
germs. The other rabbit inoculated with mucus from below the vocal chords died in 
3 days with the same lesions and bacteria present. 

2. Other affections, — Pig No. 180. This pig was exposed to hog cholera in an infected 
pen March 13, removed March 18. It survived the exposure and was killed June 4. 
Its internal organs were normal with exception of the peritoneal cavity, which con- 
tained a considerable quantity of cloudy serum, the result of peritonitis. Four 
rabbits were inoculated from mucus obtained from below the vocal chords and at the 
base of the tongue. The two inoculated from the latter source died in about 24 
hours. In both the spleen and blood contained lar-ro numbers of swine-plague bac- 
teria. The two inoculated with tracheal mucus died within 36 hours. The spleen of 
both contained large numbers of the swine-plague bacteria. 

Pig No. 202. This animal was fed. in May, 1889, with small quantities of culture 
liquid containing hog-cholera bacilli twice a day for a week without producing a 
fatal disease. November 15 it was penned with No. 119, which harbored the swine- 
plague germs. February 14 it was killed by bleeding, and two rabbits inoculated 
with mucus from the base of the tongue and from the larynx respectively. Both 
rabbits died, one in 3, the other in 4 days. The lesions consisted in subcutaneous in- 
flammation and exudative, partly hemorrhagic peritonitis. Swine-plague germs 
were present in the various organs, especially in the peritoneal exudate. 

No. 37. This animal had been inoculated in the lungs with a culture of swine- 
plague bacteria, October 8, 1888. January 27, 1889, it was exposed to hog cholera, 
which exposure it survived. It was killed August 16, in a very good condition. The 
only noticeable abnormal condition was the firm adhesion of the right lung to the 
chest wall by means of firm, fibrous tissue, the result of the swine-plague inoculation. 
The lungs themselves healthy. Three rabbits were inoculated with mucus from the 
respiratory passages (tongue, nose, and larynx). AU three rabbits died, two in 48 
hours, the third in 4 days. In the latter the inflammation at the place of inoculation 
and the peritonitis were most pronounced. In the organs of all three rabbits the 
swine- plague bacteria were present, especially numerous in the peritoneal exudate. 

The following case is of importance, because the bacteria obtained 
from it were tested upon pigs and found virulent. 

No. 164 survived a hog-cholera exposure early in 1886, and in June of the same year 
was transferred to another pen. It was kept until October, 1887, at which time 'it 
died of peritonitis, probably occasioned by injuries received in fighting with other 
pigs in the same pen. No bacteriological examination was made of the peritoneal 
exudate, but two rabbits were inoculated with mucus from the trachea. 

One died in 20 hours ; in the various organs numerous bacteria showing polar stain. 
The other died on second day, with the same bacteria, as demonstrated by the micro- 
scope and cultures in bouillon and gelatine. 

To test farther the relative virulence of these bacteria a peptone bouillon culture 
was prepared, of which two mice received subcutaneously one-twelfth cubic centi- 
metre ; two pigeons received subcutaneously and into the mnscular tissue one-fourth 
cubic centimetre ; one guinea-pig received subcutaneously one-eighth cubic centime- 
tre, and one rabbit one-twelfth cubic centimetre. 

The guinea-pig and the pigeons remained well. One mouse died in 24 hours, the 
other in 3 days. In the first large numbers of bacteria; in the second few. The 
rabbit died within 2 days. In this animal there was slight infiltration of skin and 



113 

aubcatiaatpoiut of mooiilation. Peritonitis. luvagination of lower oolon. In tbe 
varioua organs and peritoneal exudato onmeroiia bacteviA shoiring polar stain. 

Tbe pathogenic cbaraoCer of tbe>ae bacteria waa fiirtlier (lomonstrated by iaocLt< 
lation of swioo. 

November 11, 1887. No. 431, 6 weeks old, received iato right long tlirough cbest 
wall 2i eubic oentimetreB of a, peptooe boaillon culture. 

Ko. 432, 6 weeks old, received the same. 

No. 433, 6 Treeka old, receiveil 5 onbie ceatimetrea aubcntnneonaly, 

No. 433, tbougli affeoted bf tbe iooDnlation for a time, recovered. 

No. 431 appeared paralyzed and nnable to get up 3 or 4 dajB after the injection, 
Reapirationa somewbat quickened. It took very little food. Found dead 14 daye after 
inoculation. 

Slight infiltration in subcntia at point of injection. Kigbt lung collapaed. Pleu- 
ral cavity half fnll of blood-stained serum. Cotisicterable spongy, yellowisk exudate 
is loosely attached to the walls of the thorax, tbe Inng surface, and tbe diapbragm. 
The lung tis'oe is not hepatized exceptinga amall maas which is necrosed and which 
pn)bably represents the place where the needle penetrated. Left lung not affeoted, 
closely hound to thorax by fibrous adhesions which give way without much diffl- 
ouity. The lymph gland near root of neck very large, whitiab on section, small yal- 
luwisb foci in cortex and modnlla. Slight fibrinous exudate and eonsiderable yellow 
serum iu abdomen. In upper and middle portion of colon, tbe mucosa is covered by 
patches of a very thin grayish deposit, suggesting necrosis of tbe surface epithelium. 

Cultures ftom spleen negative ; those from plental exudate show the injected bao- 
teriu only. A rabbit Inoculated subcn taneoasly with about one drop of serum from 
tbe pleural cavity diluted in sterile beef infusion died within 48 hours. No local re- 
action or peritonitis. luuumerable polar-etaiuod bacteria in the spleen, which ia 
enlarged, ftiablc. Fewer in the liver ; still fewer in blood from heart. Cultures re- 
vealed the same organism. 

No. 433 breathed with difficulty for several days after the injection. It seemed 
feverish and refused food. Within two weeks it waa greatly improved. December 27 
its rectum was prolapsed and it died a week later. At the autopsy the cause of death 
was found to be invagination and rupture of ileum. The lungs presented some inter- 
esting features. The right lung was adherent to thoracic walls and diaphragm hj 
means of fibrous tissue not yet very firm. The left lung waa adherent in several 
places. Tbe various lobes of the right lung were bound together by fibrous tissue 
and to a tiimov lying between principal and ventral lobe along ventral border of lung,, 
Tbe tumor was removed by careful dissection, the lung tissue being alightly oon- 
denaed and bypertemic near attachment. There waa no hepatization of either long. 
The tumor felt tense, wallsabout one-eighth inch thick, inside dark red. Contents 
putty. like, grayish, made np of pas. Pericardium thickened and attached in several 
places to opicardium, which is likewise thickened, opaque. 

In a gelatine-roil culture inooulated with a particle of tbe dry pes numerous ool- 
ooiea of the injected bacteria appeared after a week. A rabbit inoculated with a 
particle of pus died in 15 ilaya with considerable local infiltration and enlarged spleen. 
No peritonitis. In the spleen a moderate number of bacteria identified in cultures 
with those originally injected into the pig. 

These bacteria were in every way like the various awine-plagiic bac- 
teria with one exception. In liquid cultures when one or two days old, 
tranalucent capsnles could be seen surrounding the bacteria individu- 
ally wheu the liquid was examined iu the hanging drop and the border 
of the drop was carefully scrutinized. This method I have found of much 
service in disclosing the presence of these glassy envelopes wheu dry- 
ing and staining failed to bring them into view. The bacteria, as they 



114 

are drawn to the border of the drop, do not touch one another, but re- 
main separated from each other by a space of definite width. Gareful 
focussing then will also bring out the very faiut outlines of the oval 
transparent capsules. In the inoculations above described, the capsules 
served as an important means of identifying these swine-plague bacteria 
from case to case. 

3. Older animals apparently healthy hut previously exposed to disease. — 
Under this head would come some of the cases already recorded and 
the following : 

No. 420 had been inoculated with hog-cholera bacilli October 6, 1887, and with 
Bwine-plague bacteria October 20. March 1, 1888, a drop of mucus taken from nares 
with a capillary pipette and forced into subcutis of a rabbit through a skin incisiou. 
The rabbit died in 10 days with exudative pleuritis, the exudate containing swine- 
plague bacteria. 

No. 219. This animal was inoculated subcutaneously with attenuated hog-cholera 
cultures September 27, 1889. It was killed January 13, 1890, and found normal. There 
was at the place of inoculation an encysted caseous mass about 1 inch in diameter. 
Three rabbits were inoculated with mucus from the respiratory tract. Of these but 
one rabbit died on the 11th day with purulent pleuritis and pericaraitis. Swine- 
plague bacteria were obtained from the exudate and their virulence tested by inocu- 
lating a fresh rabbit with a pure culture. 

4. Animals not known to have been exposed to disease. 

October 6. Nasal mucus obtained from the nares of a healthy pig on a flamed glass 
rod is stirred up in sterile water and one-half cubic centimetre injected subcutane- 
ously into two rabbits. 

No. 1. Dead October 12. Purulent thickening of the subcutis at point of inocula- 
tion and extending thence over abdomen and thorax as a sanguinolent effusion. Per- 
itoneum roughened. A cover-glass placed on csecum, removed and stained, shows 
immense numbers of bacteria exhibiting the polar stain. The same bacteria scarce 
in blood, spleen and liver. 

No. 2. Dead October 13. Lesions as in No. 1. Exudative peritonitis with ecchy- 
moses on caecum. 

Cultures from both cases on gelatine and in bouillon contain only swine-plague 
bacteria. 

Additional inoculations were made February 2 and March 1, 1888. 
Nasal mucus from supposedly healthy pigs was collected in a capillary 
pipette and a drop forced with a rubber bulb into a subcutaneous pocket 
made by an incision through the skin. The incision was closed with 
collodion. 



Date. 


Rabbit 
No. 


From 
pig No. 


Beanlt. 


Feb. 2 
Feb. 2 
Feb. 2 

Feb. 2 
Mar. 1 
Mar. 1 

Mar. 1 
Mar. 1 
Mar. 1 
Mar. 1 

Mar. 1 


1 
2 
3 

4 
5 
6 

7 

8 

9 

10 

11 


483 
484 
403 

491 
490 
491 

493 

483 
482 
484 

468 


• 

Nefi^atlye. ^ 

Dies in 48 hoars. Larp^ nombers of polar-stained bacteria in 

blood, spleen and liver. 
Negative. 
Do. 

Dies in 7 days. Extensive pnrolentinflltration of snbontis; ool- 

tures negative. 
Negative. 

Do. 
Dies in 13 days. Pnenmonia and exudative plenrttis. 
Dies in 7 days. Same as No. 6. Bacteria obtained from spleen 

in cnltnres fatal to a rabbit in 48 boars. 
Dies in 13 days. Same as No. 9. 



115 



M 



No, 468 belonged to one lot brought to Station January 4, 1888. 

Noa. 490 to 493, iuclusive, to anotlier lot broiifibt to Station January 
25, 1888. 

Noa. 481 to 484, inclusive, to still another lot brocglit to Station Jauu- 
ary 10, 1888. 

The inoculation diaoaae iu tlie rabbitfl v.^ried coaaiderably. In one, death ensued id 
48 hours. Noa. 6 and 10 died ia 7 days, and in both there tros exteuaive purnlent id- 
flltratiou of subcotis over abdoineu and thorax. Finally, in Nos. ami 11 there was 
exudative pleurltia with pneomoma. In No. 9, oae-balf, iu No. 11, tbe whole of Cbe 
left lung hepatized. In the pleuritic exudate and the lung tissue large uuiubera of 
polar-atuiced bacteria. 

None of the three lota of pigs were tlioa free from these bncteria. It will lie noticed 
that the muena from four piga waa teated twice and that tho reaulta were not onifortn. 
No animal produced diseauo more than once wliilc nun fitiled to prodnce diaeiMe both 

PiKNo. 30;i, January 28, 1890. This auiuial was tnkou from a herd which had 
been purchased January 25. Tho farm from which it camo la said to have bad soma 
form of awine disease OD it nearly a year ago. The thoracic organs of the pig were 
normal in appearance. Two rabbits were inoculated, one with mucus from tbe 
larynx, the other with mucus from the pharynx. Both uuccumbod on the third and 
I fourth day, respectively, to exudative peritonitis. Iu the exudate the swine-plague 
^^H bacteria were quite abundant. 
^^V December 24, 1890. No. 44T, about 4 uiontha old, received yesterday with a lot of 
^^" other piga from a farm which has been fieo from diaeaae for aeveral years. The pig 
was killed by l>lee<]ing, and ulthungh it seemed well, tbe anterior half of both Innga 
was fouud diseased. The diseased lobes were of a pale red appearance and seemed 
u'dematous rather than hepatized. There was coDsideruble muco-puruloiit secretion 
in the smaller bronchi'. In the terminal bronchi of the principal lobe some Inng 

One rabbit was inoculated snbcutaneously with a particle of lung tiesue and two 
with tniicus &om base of tongue. The former remained well ; both the latt«r died. 

■ One died within 40 honnt with considerable local purulent iuQltration of ekin and 
■ubcntis. Spleen enlarged, containing bacteria ahowing polar atain. Culture on agar 
'from spleen contains only swiuo-plague bacteria. The second rabbit died in 3 days, 
with very extensive auboutaneoua infiltration and exudative jieritonitia. Sploeu en- 
iBrgedand dark colored. In the organe few bacteria, in the exudate a large number. 
Cultures from epieen and exudate contain only swiue-plague bacteria. In order to 
test tho virulence of these bacteria in pure cuUurea, an uduU rabbit was inoculated 
aiibontanaously with an equivalent of one five-hundredths cnbio centimetre houlllan 
onlture dilated in bonillon. The rahliit died on tbe fourth day with lesione like 
thow of the preceding cai>e. 

15. The reanlta thna far obtained must not lead as to infer that all 
Btriue carry with them bacteria closely allied to swine-plague bacteria. 
Some herda are entirely free from tbem, aa the following statements will 
show: 
Pi, 
Coin 
oalle 
"^ 
Ukei 



Pigs Noa, 116 to 133 were received January 4, 1889, from a place in the District of 
t Columbia where swine diseases have not prevailed for a number of years, and whore 
Is bestowed ou tlio rearing of swine. From fonrof these, nasal nincua was 
I onlleoted and four rabbits inoculated subcutuneoualy with one or more drops. All 
^remained well. 

From another lot of eight, received February 4, two were tested. TlieieBnlta were 
ikenise negative. 



J 




To test the matter somewhat more thoroughly in subsequent case^, 
the auimals to be examined were killed and mncus taken from varioua 
places iu the upper air passages. 

No. a05, one of a, lot regarded honltlij, killud Juno 15, 1889. Pericardium flriuly 
adlieroQt to tlie huart. Tliree rabbits inoculated with miioiiH from posterior Dsrea, the 
boae of tongue and from bctlow vocal cords. All remained well. 

No. S07, from auotber lot, killed on the same dn;. Tlie orgaua were iu geueral 

lieBltby with the exception of the ]ar(;o iuteatiue. The mucous membraue appeared 

to be in a state of mucous degeneration. It was snollsn, partly traoHlu cent. On 

valve an<l along colon smnlV patches of a thin, friable, yellowish deposit. Fire rab- 

e inoculated— two from this deposit, three with mucus (com trachea, poater- 

9, and base ot tongue. All remained well. 

It would be going too far to maiutaia that all forms of hiug disease 

e the result of the inyasion of swiue-plague bacteria. The absence 

of these bacteria is well illnatrated by an outbreak of hog cUolora in- 

vestigatfid iu the fall of 1887, and reported in the special report on hog 

cholera, pp. 39-52. 

In about one- half of the fifty cases there was some disease of the lungs. 
This was in part simple collapse, in part broncho- pneumonia invoWing 
one of the small ventral lobes. Of the sixteen rabbits inoculated with 
particles of diseased lung tis8i',j from sixteen cases, four survived and 
the remainder died of hog cholera. Swine-plague bacteria were not de- 
tectetl. It is reasonable to assume that if they had been present in the 
upper air passages they would have sooner or later invaded the diseased 
lung tissue and appeared in the inoculated rabbits. . 

In addition to the foregoing experiments a few inoculations into rab- 
bits were made with mucus from the cajcam of healthy pigs, but they 
were negative so far aa swine-plague bacteria are concerned. The 
mucus was taken from the crypts on the ileocecal valve and the sur- 
face of the patch in which they are imbedded. 

Caicum No. 1. One rabbit and two mice inoculated aiibcutaoeoUBly , No result. 

Cxcum No. 3. One rabbit inoculated. Diediu S days. Exlonsive aau gain olent and 
parulenl inllamuiatiou of the subontis of abdomen. Fuyur'a patches swollen and pig- 
mented. The appendix of mecum swollen, blackish; ulcoiB ou mucous sorface. Cal- 
tares from internal organs wholly negative. 

Caicum No. 3. Que rabbit inoculated. Died in 8 days. Uubcutis and appendix as in 
preceding case. Caltnres sterile. 

Ciecnm No. 4. One rabbit inoculated. Died in 11 days. On thigh, an abaeess be- 
tween mueolOB half as large as a hen's egg. Center disintegrated into a curdy mass. 
No other lesions. In the pus of abscess lurgn numbers of bacilli of various lengths, 
staining feebly. They fail to grow in culture media. Internal organs free from 
bacteria. 

It may be claimed that the presence of swine-plagne bacteria on the 
mucous membranes of healthy awine and other domesticated animals 
is an argument against the specific character of swiue-plague bacteria, 
and hence against the existence of a specific disease induced by them. 
We have already met this argument by the numerous successful inocu- 
lations of swine-plague bacteria into healthy swine, by which a dieeaeo 




■ 
■ 



tlie Datura! disease has been produced. The atteunated virulence 
of tbe bacteria iu tiie air passages makes it probable tliat few of tUem 
are able to produce disease excepting iu a secoudary rOle, 

Tliere are two infectious diseases iu inau wbich iu this respect offer 
some strilviug analogies to swine plague. The disease kuown ascronp- 
ons pneuuiouia is chiefly associated with bacteria {Diplocoecus pneu- 
monia;) bearing much resemblance to swine-plague bacteria. These 
bacteria are now regarded as the chief, if not the ouly, cause of pneu- 
monia. Strangely enongh, bacteria not distinguishable from tliese are 
occasionally encountered iu the saliva of healthy persons. Senator, 
Pasteur, and Sternberg were among the first to call attention to the 
fhct that rabbits inoculated with sputum may die of septicsemia, and 
the bacteria found in the internal organs of these rabbits were identi- 
fied subsequently with the bacteria of pneumonia. We have thus a 
complete analogy between swine-plague and croupous pneumonia. 

In another disease facts of simitar nature have recently come to 
light. Koux and Yersin' have found in the mouths of about 10 per- 
cent, of all healthy persons examined bacilli which have no pathogenic 
effect, but which resemble closely the bacilli of diphtheria, which, in 
fact, they regard as very attenuated forms of the diphtheria bacillus. 
LiifHer and others had previously fonnd similar bacilli iu the months 
of healthy persons. 

There are several important questions raised by the discovery of at- 
tenuated forms of disease-germs in the surroundings, and in the body 
of uTiimals. Do these bacteria belong to the same species as the viru. 
lent forms, and, if so, can they gain virulence enough under certain 
circnmstances to produce disease} That pathogenic bacteria may gain 
in virulence has been shown by Pasteur, Eonx, and others. Whether 
this applies to ali kinds of disease-germs may be reasonably doubted, 
and the experiments thus far tried by us to increase the virulence of 
attenuated hogcholera and swine-plague bacteria have shown that by 
passing them through susceptible animals no decided increase in vira- 
lence is observed. On the other hand, so far as methods are able to 
inform us, these same attenuated bacteria found in the air passages of 
heal thy animals, and the swine- plague bacteria proper found in disease, 
do belong to the same species, and must be regarded as simple varieties. 

These discoveries also point out that the one property of pathogenic 
bacteria which must receive special attention is their relative virulence. 
This seems to l>e the one factor which determines the severity and the 
commndicability of infectious diseases. 





BEIEF REVIEW OF THE UTESTIGiTlOK OF OTIIER OBSERYEBS. 

AMERICAN. 

Of tbe work done iu iDve3ti<;fitiDg tlie diacases of swiiie tbat of Dr. P. 
S. Billings seems to have aroased ranch attention, cliiefly betiiiiise of tlie 
polemical attitnde which he has assumed and the peculiar maimer in 
which he has criticised the worlt of the Bureau of Animal Tudnstry. 
His results are contained in a volume of 414 pages, published by tbe 
[Jniversitj- of Nebraska in 18SS, in connection with wliich institutiou 
the work was carried on. 

In this volume Billings has given us very little opportunity to dis- 
cover how mnch work was actually done in arriving at the various theo- 
ries and conclusions contained in the volume. The statements of ex- 
periments are exceedingly meager and the bacteriological work very 
nn satisfactory. 

It is evident that in work of this kind the discovery of the causes of 
disease is tbe fundamental problem, and all other problems must at tbe 
outset be subservient to this one. The bacteriological work is there- 
fore the most important, A perusal of the report of Billings shows that 
he has contributed nothing whatever to theelucidationof this problem, 
while his obstructive attitude has confused and retarded the progress 
in the right direction in a marked degree, as the following statements 
conclusively prove: 

He has assumed the position that there is but one infections swine 
disease in the country, while the investigations of the Bureau of Ani- 
mal Indnstry have maintained tbat there are at least two. The various 
ci'ilicisms which Billings has writtenof the workof the Bureau need not 
engage our attention here. They are interesting enough :o be read in 
the original, but they all collapse in view of investigations puljlisbed 
in the present volume. That the earlier iuvestigations of the Bureau 
ou swine plague were not absolutely demonstrative no one will deny. 
That they, however, pointed very directly to another disease is shown 
by pathological as well as bacteriological considerations— a sever© 
pleuro'poeumonia associated with specific pathogenic bacteria easily 
differentiated from the bacteria causing hog cholera, Tbe repeated 
occurrence of pathogenic bacteria in case after case of an outbreak could 
not well be overlooked or explained away by any pathological consider- 
ations. The duty of au investigator in another section of the country 

118 



I 



woald have been the carefnl inveBtigatioii of his own territory ab to the 
preseuce or absence of sucli diseases. 

What is the nature of the baoteria described by Biliiuga as the cause 
of the infectious swine diseases f 

If we examine pages 103-116 of his report we shall find a brief ac- 
count of the bacteria iu qnestiou. If we examine his description and 
figures on page 104, and compare them with the swine-plague bacteria 
described in the foregoing pages, it will be observed that he haa before 
him swine-plague bacteria and not hog-cholera bacilli. Of this he seems 
to be himself aware, for on page III he states that the hog-cholera 
bacteria, as described in the reports of the Bureau, have no existence, 
i, e., are fictitious. 

Nest, the growth on potato as observed by Billings is anything but 
that of swine-plague bacteria. It may be that of hog-cholera bacilli or 
of allied intestinal bacteria. 

The remarks about gelatine cultures may apply to at least a dozen 
Bpecies of bacteria. 

The observations about the movement of these bacteria is equally in- 
definite. It might apply very well to the Brownian motion of swine- 
plague bacteria, but it certainly does not describe the rapid motion 
across the microscopic field so characteristic of hog-cbolera bacilli.* 

This very incomplete description of the bacteria found by Billings 
leaves us, therefore, entirely in the dark. The form, mode of staining, 
and the motility, apply to swine-plague bacteria, the potato growth, 
perhaps, to hog-cholera bacilli. How can we reconcile this conflicting 
account f Bearing in mind the fact that in the organs of swine which 
have succumbed after extensive lesious of the lungs and large intes- 
tine, it is not an uncommon thing to find various forms of bacteria, 
Sflciiiits coli, non-motile bacilli (also found in intestines), streptococci, 
gas-producing, spore-bearing bacilli, etc., either alone or associated 
with the real cause of the disease, we liud ourselves unable to explain 
his discovery because we have no full and accurate report of investiga- 
tions actually carried out. The description he gives may apply so far 
as we know to the bacteria tbund in one bog, in five hogs, or in a hun- 
dred hogs. It is obvious that the amount of conviction his statements 
carry depends entirely upon the number of animals to which such state- 
ments apply. 

An explanation which covers the ground of the statements made by 
Billings fairly well is one which takes into account the mingling of two 
diseases. Since 18S6 we have seen very few ontlireaks of hog cholera 
not associated with swine plague. The investigations recorded in these 
pages show how frequently it may occur that a culture may contain 

*Iu Itis report on tbe "corn-stalk" dUe&^e of cattle, pnga 136, Billiuf^ aeems to 
have lost bis doubts oonoeming the motility of tho liOR-cliolora (swine-plagut 
filllin^) bacillus. He there cooBiders it b; comparisoa " tu posaesa moet act 
movemenlB." 



I 



120 

both swine-plagae and hog cholera bacilli, or that the cultures from one 
animal contain only swine-plague bacteria, those from another of the 
same herd only hogcholera bacilli. Again this report illustrates that 
we may be called upon to investigate an outbreak of swine disease in 
which hog cholera bacilli are demonstrable in every case, and in the 
succeeding one we may find only swine plague bacteria or a mixture of 
both germs. 

It is highly probable that Billings had under observation now one 
germ, now another, and occasionally a mixture of both. With this ex- 
planation* in mind we may easily interpret the conflicting account of 
the bacteria given by Billings, especially if such statements are based 
on a small number of cases only. This explanation is the more plaus- 
ible when we turn to the method used by Billings in obtaining pure 
cultures from animals. While, on the one hand, his cultivation methods 
were insufficient to determine accurately whether cultures contain more 
than one organism or not, he unwittingly assumes, on the other hand, 
first, that the bodies of diseased swine always contain only one kind of 
bacteria, and, second, that this kind is always the same. These as- 
sumptions anyone will recognize on reading page 103 of his report. 
How much information can be obtained by such deductive method of 
I)ursuing a most inductive branch of scientific investigation, the reader 
must be allowed to judge for himself. .It may be noted, however, that 
such vicious methods furnish ample material for the attack upon work 
done by others. 

Again, the examination of 5 hogs, or of 500 hogs, made over a lim- 
ited territory with a uniform result, does not permit us to generalize 
negatively on the swine diseases of the remaining millions scattered 
over the whole country. This attitude is to be regretted the more 

* A good illustratioa of the plausibility of this theory may be found on pp. 191-197 
of the report of Billings, where the results of some inoculations of smaller animals 
are detailed. These may be tabulated. 

One rabbit, inoculated with one-half cubic centimetre bouillon culture, snbca- 
taneously, May 14, dies in 3 days. 

One squirrel, inoculated with one-half cubic centimetre bouillon culture, subca- 
taneously, May 14, dies in 3 days. 

One rabbit, inoculated with one-fonrth cubic centimetre spleen emulsion of preced. 
log rabbit, May 17, dies in 6 days. 

One rabbit, inoculated with seven drops of blood, etc., from pig, subcntaneously, 
May 23, dies in li days. 

In this series the dose injected into the first rabbit is too large to bring oat the 
differential characters of either hog-cholera or swine-plagne germs. In the second 
rabbit death was probably due to hog-cholera bacilli. In the third it was certainly 
due to swine plague, since the most virulent hog-cholera bacilli would not destroy 
rabbits in the dose used, in less than 4 to 7 days. In the report on the corn-stalk dis* 
ease already referred to (1889), Billings states that a certain germ could not '' be 
that of swine plague (hog cholera) on account of its acute fatality.'' These later 
opinions are refreshing in being in the right direction as far as hog cholera is con- 
cerned. 




■ ■wlien we reflect on the facttLat the area of diseases is largely flefiiied 
by fe'eographical, cliiiiatid, and economic factors. 

In bis report, Billiuga tlirmisliout denies the existence of the Iiog- 
cliolera bncillas first described in the Barean Report for 1835, This 
denial may be fonud scattered tlirougliont the report, Theu we must 
assume that he considered the swine-plague bacteria as the caase of 
American swine diseases. This assumption is proven by his repeated, 
almost continaoua, discussion of the Enropean Schweineseuclie and WilA- 
scuclie.* This continual dragging iu of the work of Enropean observers 
can only be understood by assuming a great similarity or a possible 
identity between the bacteria in the liauds of Billings and those of 
Schireineseuche, as described by Loffier, Hchiitz Hiippe, and others. On 
Ihe other hand, tho pathological appearances in these diseases differed 
80 greatly that Billings found it necessary to occupy the greater part 
of bis report in needlessly pointing out lilcenesses and differences, 
I T7p to this poiut-, then, it seems that Billings regarded his swine dis- 
I ease bacteria as the same morphologically with the German Wildseuche, 
' and that he denied the existence of the bog cholera bacillus. Mean- 
while we studied his publications and made every effort to determine 
what bacteria he was studying, but without success, owing to the im- 
perfect diagnosis given and the peculiar intermingling of the proper- 
ties of the bacteria of hog cholera and swine plague found in his report. 
[ In 1889, however, to onr surprise, the commission appointed to throw 
I some light on this matter found Billings iu possession of real bog-chol- 
era bacilli. Cultures wore sent by bim to Berliu, where a comparison 
of these cultnres with some sent from this laboratory likewise demon- 
strated that his swine-plague bacteria were identical with the hog- 
cholera bacilli discovered iu the Bureau laboratory in 18S5,f neariy a 
year before Billings began his work in il^ebraska. 

All these facts make it highly probable that Billings bad unwittingly 
studied at least several kinds of bacteria, among which the swine-plague 
bacteria of this report must have played an important part. In a recent 
article f on swine diseases, prepared under Hiippe, the author mentions 
the fact that Billings had sent cultures at two different times, which, 
though considered by the sender as identical, were really quite diil'er- 
ent. In another article Caueva,§ working under Hiippe in Freseniua' 
laboratory, endeavors to group the various bacteria producing swine 
disease, and in so doing separates the bacteria sent by Billings from 
hog-cholera bacilli, because the former were less actively motile, coagu- 
lated milk, and produced only local reaction after subcutaneous inocn- 
I lation. Tbey also failed to infect by feeding. While these bacteria 
I may represent an attenuated variety of hog-cholera bacilli so far as their 




' Compare also page 141 of tbia report. 
t FroBclj. ZeilBclirift flir Hygiene, ix, 8. 
tBiiDzI-Fudoru. Arobiv f. Hygiene, xii, 
i CeDtralblatt t Bakteriologia, ix, B. 6 



A 



I 
I 



122 



virnlence ia concerned, none of the liog-cliolera bacilli firom nnineis 
oiia mid widely separated localities esamiDed in tbla laboratory ever 
produced coagulation of milk. Bacteria of the latter class are chiefly 
harmless intestinal parasitea which closely resemble hog-cholera bacilli 
(baeillug coH) and which occasionally appear in cultnres from cases of 
Bwine disease. 

If, therefore, Billings bad fonnd the bog-cholera bacillus the qneatioa 
arises : Why did he fill np his report with pages of extracts, comment, 
and criticism of the European Schiceineseucke, when the bacteria of hog 
cholera and Sehiceinesevche are wholly diflerent, as every observer has 
admitted who has compared them T Such discussions are not only use- 
less, but misleading, when brought to bear upou the condition of things 
in OOP own country. In view of these facts the question also arises: 
Why did Billings so vehemently oppose the hog-cholera bacillus 
described in the Bureau Report of 1885, and found by us to exist in 
Nebraska before Billings entered upon his work there, if he had it 
under observation himself! These contradictory positions can only be 
interpreted by the assumption made above, that Billings had at first 
one or several kinds of bacteria under observation differing from the 
true hog-cholera bacillus. 

If we are nevertheless to couclude that Billings has finally settled 
upon hog-cholera bacilli as the cause of swine disease in Nebraska, any 
further comment on his work could only be taken up under hoff cholera. 
The questiou whether there is another disease besides hog cholera is 
settled in the afBrmative by the work reported ia these pages. This 
second disease seems to be in fact the disease which Billings has had 
in mind in his controversies, and his criticisms of American and for- 
eign work. Unfortunately, however, it has turned out that he has 
mistaken the disease, and now bis opposition strangely enough has 
shifted towards the swine-plague bacteria, since an attitude of opiHisi- 
tiou towards bog cholera uoald no longer be maintained.* 

It is clear to any unbiased reader that work which fails to grasp any 
positive truth, and is continually shifting its base to avoid the necessary 
consequences of serious errors, and which goes beyond its confines not 
only to criticise, but to discredit in every manner possible the work of 
other observers, can not be seriously taken into consideration as advanc- 
ing in the least degree our positive knowledge. 

Duriug the years 1887-'89, Professor Welch, in conjunction with A. 
W. Clement, V. S., and F. L, Kussell, V. S., investigated a number of 
outbreaks of swine disease in the neighborhood of Baltimore, Md. In 

* A glniiile Htatement of tlie position ofBilliDgH wonld reiul Ihos! 

1. OppositioD to liog-choierii bacteria discovered in Bore&n laboratory in ldd5. 
Evidence iu his n'ritiiiga nil points to Hwine plague. 

i. Discovery by eomraission and Gerinuu observers tliut his germ and the liog- 
oholern bacillus ore Identical ; lience, 

3. Opposition to swine-plague bacteria. 



1 

I 



a proliminary report pablished in the Johns Hopkins IIoHpital Bulletin, 
December, 1889, Welch gives a brief summary of the resulca obtained 
np to that (late. These investigators eueountered in some herds only 
hog-eholera bacilli, in others only swine-plague bacteria, and in still 
others both kinds of bacteria. They have not been able to fix npon 
any anatomical diftereuces between the herds in which hog-ehotera ba- 
oilli were found and those in which only swine-plague bacteria were de- 
tected, for in Jill cases intestinal lesions were present. The description 
of the two kiuds of bacteria agrees in every respect with that published 
in the various reports of the Burean of Animal Industry since 188.5. 
With both the.anthors were able to prod nee disease in swine, intestinal 
lesions witli liog-cholera bacilli and lung lesions, associated with inflam- 
mation of the serous membranes, with swine-plague bacteria. 

While the results agree in e\ery particular with those obtained by ns, 
Welch expresses himself with caution concerning the r61e of swine- 
plague bacteria, liecauso in the herds studied none were free from intes- 
tinal lesions. He suggests the possibility of overlooking hog-cholera 
bacilli because they may remain limited to the intestinal tract, a possi- 
bility to which we have called attention in the report for 1887-'88, and 
in these pages. On the other hand the facts that pneumonia may be 
produced by swine-plague bacteria, and that .a swine disease exists in 
Germany in which pneumonia without intestinal lesions is associated 
'vith swine-plague bacteria, "suggest that this organism is also the 
^taitse of a similar affection in this country." 

and 1890 Dr. J. A. Jeffries" made bacteriological observa- 
ttfons in several outbreaks of swine disease of an infectious character. 
'Ill one pig were found a large spore-bearing bacillus, a short bacillus, 
aud swine-plague bacteria.! The short bacilli Jefi'ries found non-path- 
ogenic, while the third form, the swine-plague bacteria, be considers 
the cause of the disease. 

The description of the pathological appearances of the diseased pigs 
and of the swine- plague bacteria found by him, taken together with the 
inoculation experiments and the absence of hog-cholera bacilli, make 
it pretty certain that the disesise was identical with that described in 
these pages. 

Through the kindness of Dr. Jeffries a culture of the swine.plaguc 
bacteria was sent to the laboratory, where a comparative study of the 
morphological aud x>^thogeuic characters showed them to be an at- 
tenuated variety of awine-plague bacteria, not distinguishable from 
those described in these pages. A few of the inoculations on rabbits 

1 'ECiolDfty of two imtbreaks of disease tuaong hogs. The Joumal of Comp. Uedi' 

■ eilie, December, ld90. 

tThe »]iore- bearing baoillni I havo found in m.iof ontbreaka as the result of poat- 
mortem growth. lo somo pigs sections from ever; organ show these long wnvy tila- 
ments fllliug np the capillaries aud penetrating the tisane in ail directions. See also 
page BO of this repoit. 



J 



124 

are given to illustrate the variety of lesions which these bacteria may 
liroduce. 

The ciiltare was first tested by plate cultures and two rabbits inoculated from a 
bouillon sub-culture. 

June 3, 1890. One rabbit received one-eighth cubic centimetre subcutaneoasly, and 
one one-eighth cubic centimetre into an ear vein. 

In both the temperature was between 105° and 106° F. on the sixth day. On the 
tenth day the first had recovered; the second, unable to move hind limbs, was chloro- 
formed. The only lesions observed were two abscesses, one on the right tarsus, the 
other on left elbow joint, both communicating with the joint cavity. 

The culture was thus considerably attenuated. Nothing more was done till Decem- 
ber, when the same culture, passed through a series of agar tubes meanwhile, was 
used, because attenuated, for some preliminary immunity experiments on rabbits. 
The virulence of the bacteria was much greater now, as the following inoculations 
prove. Attention is called to the great variation in the lesions produced, and to the 
pneumonia in No. 5. 

December 8, 1890. Two rabbits (Nos. 1, 2) received subcutaneonsly one-eighth cnbic 
centimetre bouillon culture, and two (Nos. 3, 4) the same dose into an ear vein. 

No. 1 dies in 7 days with extensive purulent infiltration of the subcutis over abdo« 
men and thorax, purulent peritonitis and pleuritis. 

No. 2 survives. 

No. 3 very sick on the fifth day and chloroformed. A subcutaneous purulent in- 
filtration extends from place of injection on the ear over the greater part of face. 
No other lesions observed. 

No. 4. Temperature on third day 105.5° F. Dies on the fifth day with peritonitis 
and pleuritis. The exudate stretches in the form of delicate grayish viscid threads 
between coils of intestine when these are lifted up, and from chest- wall to pleura of 
lungs. The exudate a mixture of leucocytes and immense numbers of bacteria. 

As these experiments were designed to find a dose which would not prove fatal 
they were repeated. 

December 16. Two rabbits (Nos. 5, 6) receive a subcutaneous injection of one-eight- 
hundredth cubic centimetre bouillon culture, and two (Nos. 7, 8) an intravenous in- 
jection of the same dose. 

In all cases the culture was diluted and one- fourth cubic centimetre of the dilution 
injected. 

No. 5 dies in 9 days. Extensive purulent infiltration of subcutis over abdomen and 
part of thorax. Exudative peritonitis absent. Purulent pleuritis with exudate es- 
pecially abundant on right lung and chest- wall. Hepatization of the two small anterior 
and portion of principal lohe of same side. The hepatized lobes in part dark red and 
pale red, firm and enlarged. Epicardium covered with a membranous exudate. In 
the exudate numerous bacteria showing the polar stain. 

No. 6. Temperature on second day 105° F. Dies on sixth day. Extensive purulent 
and sanguinoleut infiltration of the subcutis as in preceding case. Spleen barely en- 
larged, somewhat darker than normal. No peritonitis or pleuritis. 

No. 7. Temperature 105.2° F. on second' day. Dies on thirteenth day. Extensive 
subcutaneous infiltration as in preceding case. Straw-colored, elastic membranous 
exudate on liver, spleen, and caecum, and between coils of large intestine, matting 
the various organs together. The exudate is easily pulled away and consists of fatty 
pus cells and immense numbers of swine-plague bacteria. In pleural sacs some 
serous exudate. Pale red hepatization of a small portion of the small anterior lobes 
of right lung. Spleen moderately enlarged, dark. Peyer's patches pigmented. 

In November, 1890, Prof. T. J. Burrill, of Illinois University, sent 
two agar cultures of bacteria obtained from an outbreak of swine dis- 




I 



» 



125 

e in Illinois. Botli cultures were carefully esamiaed and found to 

contain only swine-plague bacteria. Tp teat the pathogenic character 

two rabbits were iuoculated. These inoculations prove the essential 

identity of these bacteria with swiue-plagne bacteria. 

NoyBinljer 7. From a bouillon calture, 1 day old, one-tenth cable oentlmetre was 

I injected nndei tlie aklii of a large rabbit. 
November 11. Rabbit fouud deud this ruorDtug, At poiut of inoanlation pnrulent 
thlckeniag of tbe eubcatis. Csonm, coloa and rectum sprinkled with hemorrhages. 
Slight viscid exudate on nxQucn which contains largo unmbeia of the injected bac- 
teria. Liver aud kidneys pale. Spleen barely enlarged, dark in color. The agar 
and bouillon cultures from blood, spleen, and abdominal exudate contain only tbe iu- 
oculated bacteria. 

November 13. A rabbit received subcntaneoasly on side of abdomen, one-tenth 
cnbic centimetre booillon oullnre prepared from the second original uulture. Bab- 
bit dies in 40 hours. A very slight iniiltration at tbe place of inoculation. Spleen 
elightly enlarged and eugniged. In it a consiileTable number of swine-ptagno bact- 
showing the polar stain. An agar culture from the spleen contains these 
iMcteris only. 

GEKMAN. 

Of great interest and importance to as are the German investiga- 
'tions of swine plague (Schweineseucke), because this disease does not ap- 
pear to be complicated with any other disease, as is tbe case in our own 
country where swine plague and bog cholera are so frequently asao- 
eiat«d with each other. 

Probably the first investigation in which swine-plague bacteria were 
observed is that of Lijfrter.* Only one pig was encountered iu the 
course of a series of investigations on the continental disease of swine, 
known as rouget and Eothlaiif, in which these bacteria were found. In 
this case the lesions are given as follows : 

The skin of abdomen, sexual organs, and neck of a livid red ; enormous mdema of 
the (sub) cutis of the neck, extending backwards between forolimbs. Pharynx red- 
deued and swollen. Laryngeal and tracbeal mucosa intensely dark red. Lungs but 
slightly affected ; on the right some dark red regions, containitig but little air. 
Nothing abnormal iibout the heart. Cloudy swetiiug of liver and kidneys. Mucosa 
of stoniaoh and upper portion of duodenum intensely reddened. Remainder of intes- 
tines unchanged. Mescnterio glands not enlarged. Spleen rather large, dark bluish 
red, qaite firm. 

The bacteria obtained from this case resembled those of rabbit septi- 
c^mia.t They killed inoculated rabbits and mice in 24 hours. Guinca- 

* Arbeiten a. d. kaiserlichcn Gesuodbeitsamte, I (18d5), S. 51. 

t The term rabbit septiciemia originated in a sertea of experiments on rabbits by 
^Chftky, in 1881 (Mitlheilungtiit a. d. kaiatrl. GesaitdhaiUame I, IBSl, S. 102), wlio pro- 
ilaced in these animals by the injection of poll a ted water a rapidly fatal disease 
oansed by bacteria closely resembling those of swine plague and some other animal 
diseases. (See p. 141 of this report.) The writer fonnd booterio causing suptio dis- 
eases in rabbits, probably ideutiuul with these in 1SS6 (Journ. Conip. Med. and Sur- 
gery, Jan., liiiS7). Prior to Galfky's work, R. Eooh aud Davaine had been esiieri- 
nenting with a similar disease in rabbits. 



126 

pip^ lived from 2 to 3 days after inoculation. In all there was extensive 
sero-sangniuolent infiltration of the subcutis, starting from the place of 
inocalation and extending in some over thorax and abdomen. In one 
the intestines were covered with a sangninolent and fibrinous exudate. 
Of three pigs inoculated (probably with minimum doses) one died in 
2 days with the following lesions : • 

Skin of abdomen bluish red; enormous cBdema of skin ; lungs hypostatic ; macosa 
of stomach deeply reddened ; spleen unchanged; kidneys parenchymatous; mesen- 
teric glands not swollen. 

This first reported case is interesting in that the lungs were not the 
seat of disease. 

The disease of Schweineseuche was established in a more definite man* 
ner by Schtttz in investigations carried on in 1885.* 

Since then it has been generally recognized as a disease distinct from 
Bothlavf. The material with which Schiltz worked at this time con- 
sisted of — 

1. The stomachs, spleens, and livers of three pigs, more or less decom- 
posed, June 15, 1885. 

2. The stomachs and spleens of several pigs, August 27, from Putlitz. 

3. The trunks of two pigs, November 19, from Putlitz. 

4. Two entire pigs, December 13, from Putlitz. 

In a footnote the author states that several additional cases of this 
disease had come under his observation subsequently. 

In the four pigs of which SchUtz was enabled to examine the viscera, 
all were affect'Cd with more or less hepatization of the lungs associated 
with pleuritis, more rarely with pericarditis. In one of these four cases 
there was found, in addition to lung disease, peculiar caseous degen- 
eration of the joints of the limbs, involving the bones and surrounding 
muscles. The various lymphatic glands were greatly enlarged and con- 
tained cavities filled with grayish yellow, semi-liquid masses.! In the dis- 
eased lungs were disseminated yellowish necrotic foci varying in size. 

From all the cases examined bacteria were obtained which were evi- 
dently the same. SchUtz described them as follows : 

When stained with gentian violet they show in their central portions an unstained 
region surronnded hy a layer stained blue. The thickness of this layer is greater at 
the poles, so that the extremities appear more deeply stained than the sides. When 
deeply stained they appear uniformly blue. As these organisms stand between mi- 
crococci and bacilli, they may be called bacteria. They are 1.2 jn long and 0.4 /< to 0.5 
// broad. They multiply in the following manner : They become twice as long as 
broad ; show distinctly rounded extremities, and stain like the organisms of rabbit 
septicaemia and fowl cholera, so that between the deeply stained ends abont one-half 
or a third of the entire length remains unstained. Careful examination shows, how- 
ever, that the colored end pieces are connected with each other by a fine line which 
passes from one to another on each side. The end pieces then separate and the me- 
dian portion disappears. The former are at first spherical, but very soon assume an 
oval form. Hence from every organism two new individuals arise by division, in 

*Loc. cit., I (1885), pp. 376-413. 

t Compare cases on p. 75 of this report. 




127 

wbioh liy careful ataiiiiDg the aoeolored oeutral portion ia easily distinguished from 
the colored periphery. If tlio process of niaiti plication ia very rapid, qb iii piga and 
rabbitn, tbe organisms do not attain the size given uliove, hut divide before the nn- 
Btaiucd tnediau piece becomes distinctly visible. Under those oi re iini stances the or- 
ganisiDS of the succeeding generations aio smaller, only oue-half as large as, or oven 
smaller than, those which have resulted from the slow division of the bacteria. The 
younger generations are fraquoutly extraordinarily small, plainly oval, however, and 
staining uniformly in goutian violet. They do not execute any spontaneous move- 
ments, 

Theae bacteria were fatal to mice, rabbits, aud guinea-pigs. Pigeons 
ancciimbed to large doses. Fowls and rats were not suacciitible, A 
coniparisoQ of tlie virulence of tbeae bacteria obtained from tlie orRans 
of animals at tlie four different times indicated above, tbe last tliree 
being from tlie same locality, shows that it varied aligUtly: 

1. Gabbits died in 2 days, mice in 1 and S days after inoculation. Que pig 4 to 5 
months old, which had received snbcntaneonsly the contents of two Pravaz syringes 
of bouillon culture snbcn tan eon sly, died in 34 honra. A second pig treated in the 
same vray died in 48 hours. 

2. Mice died in 24 hours, 

3. Mice died in 24 hours ; rabbits in 2 to 3 days ; guinea-pigs in 4 to 8 days. 

4. Mice and rabbits died in 34 hours ; guiuea-pigs in 2 to S days ; one pig, which 
bad received a eyringeful of a bouillon enltitro into each lung, died in 2 to 3 dayH. 

Tbe lesions iu guinea-pigs, rabbits, and mice are, in tlie main, those 
obtained with the bacteria of our swine plagne. Tbe above table indi- 
cates that tbe bacteria from the last lot were the mostvirulent, asthey 
were fatal to rabbits in 2i hours, 

Through the kindness of Prof, W, H. Welch, of tlie Johns Hopkins 
University, a culture of the German swine-plague germ was obtaiued in 
1889, and a second fresh cnltnre in 1890, both from the Berlin Hygienic 
Institute. Both were compared with the American varieties of the 
Bwine-plagne bacteria. While the bacteria in both cultures were iden- 
tical in form and biological characters with the swine-plague bacteria 
of this country, their pathogenic properties varied somewhat, as will 
be seen from the following experiments : 

June 18, 1S39. From the original agar tube agar roll-cultures were made, and from 
S colonies peptone-bouillon cultures prepared. 

June Sr>. Two rabbits received subcutaneuusly one-eighth and one -sixteenth cnbio 
lOcntiaietre, respectively, 2 mice each about one-sixteenth cubic centimetre. 

June 26. One mouse dead this morning. Large, dark spleen, fatty liver. No bae- 
teria detected in cover-glass preparations from blood, spleen, or liver. On thefollow- 
iogday a few colonies had appeared in tbe agar culture from spleen. 

Jane '27. Second mouse dead. Spleen slightly enlarged, liver tatty. In spleen and 
Mood very many swine -plague bacteria, eshibiting the polar stain. 

Neitbcr of the rabbits died. The one which had rooeivod ooe-eighth oubio centi- 
metre had a temperature of 10C.4 ° F. on tbe third day. The temperature of the other 
wasnot taken, Both were iiilled 18 days aftortheinoculation. The first rabbitcin- 
,Biderably eniaciatad. Ou the inoculated thigh an abaeees us targe as a heu's egg, 
discharging from au ope^ifug thick pus. The suppuration had extended to the abdo- 
tnsn, where over iG gquar« inclies of the suhcutis was iuilUrated with put) aud firmly 
»dh*teut to abdiominal msseiea. In the second rabbit a email abscess as largo aa ft 
aaatljteuin inoeij.latejj thigh. Sflecn couaidorably enlarged. Pese^a'itt*.'****^'^*-'^^ 



128 

The attenuated condition of these bacteria discouraged any attempts 
to determine their effect upon swine. 

The second culture received in 1890 proved to be a far more virulent 
type, since inoculation of rabbits was invariably fatal within 20 hours. 
These bacteria did not differ therefore in this respect from those 
obtained from outbreaks YII and IX. At the same time their vira- 
lence was still greater, as will appear from the following trials upon 
swine : 

January 9, 1891. Pig No. 435, black male, mixed grade, 4^ months old, received 
snbcutaneoasly into each thigh 2^ cubic centimetres of a peptone-bonillon caltarey 
or 5 cnbic centimetres in all. Dies just 24 hours later. 

Pig No. 437, black and white female, 4^ months old, one-half cubic centimetre of 
the same culture injected into a vein of leg. Animal struggled so that the quantity 
injected may have been more or less than one-half cnbic centimetre. Dead in 36 
hours. 

In both animals there was considerable necrosis of the skin and oedema of the sub- 
cutis where the inoculation was made. These animals were not examined until post- 
mortem changes had appeared, owing to other work, so that the autopsy notes are 
omitted. The following two cases are of interest in that the quantity of culture 
liquid injected was smaller. 

February 11. No. 460, black and sandy female, 3^ months old, weight 60 pounds, 
inoculated subcutaneously with 1 cubic centimetre of a bouillon culture 24 hours old, 
one-half injected into each thigh. 

No. 461, animal of the same kind, inoculated in the same manner with 3 cnbic 
centimetres. 

Both were found nnable to rise on the following morning and died at 8 p. m., about 
28 hours after inoculation. 

Autopsy early next morning. No. 461 in good condition, (general blush of skin 
on ventral aspect of body and limbs. Slight reddening of subcutaneous fat. On 
both inoculated thighs the connective tissue reddened and all minute vessels injected. 
On the right the connective tissue has also a glistening oedematous appearance which 
extends upon abdomen as far as umbilicus. 

Considerable blood extravasation on pericardium and on epicardinm along the 
base of the heart, interventricular grooves and left ventricle. Veins on the surface 
of the heart distended. In right side a very dark, soft clot imbedded in thick, tarry 
blood. Lungs normal. Intestines have a uniformly reddened appearance from the 
outside. Stomach about half full of food. Mucosa of fundus hyperaemic. Mucosa 
of small intestine normal. In large intestine much dry feces. Mucosa of csecnm and 
colon of a wine-red color. Liver somewhat flabby. The surface has a mottled ap- 
pearance due to the varying hypersBmia of the lobules. In the gall-bladder a firm 
body which almost fills it out and has the appearance of beeswax. The body is 
readily crushed with the fingers. Surrounding this body is a yellowish- white, pasty 
mass. Kidneys hyperiemic. 

In cover-glass preparations of blood and kidneys many bacteria exhibiting the 
polar stain ; in liver, only a few. On inclined agar traces from blood, kidney, and 
liver transferred with wire gave rise to a very dense growth of swine-plague bac- 
teria. 

No. 460. From the cut ends of the subcutaneous veins thick, dark blood exudes. 
Skin and subcutis as in No. 461, the vascular injection on the thighs more pro- 
nounced. 

Intestines and stomach appear much reddened from the outside. On the abdominal 
walls and coils of large intestine are little lumps of yellowish-white exudate. A few 
coils of the small intestine where they touch each other show bauds of pet^hi^^ an* 
der serosa. 




129 

Condition of heart as in 461. Tliu right veHtrnl lolio of lungs fastened to pericar- 
dium 1>y tnu old ndheaions. Some tin bpleiiriil lieuiorrhagoa on priDcipal loboa. Sliglit 
rongheuiugof plenra oTer the ventral half of both lupgs, Parenoliynia nontial. 

Macosa of fundus of Btoiuaoh over an area 6 inches in diameter muoli reddeoiid, 
tlie hyperiemia extending to anbmiioosa. Sma.ll intestine contains occaBioaal patobee 
of congealed mncosa. In the large intestine hyperemia slight compared irith 4EJ1. 
Kidneys and liver as in 461. 

Inthn bloud many awine-plngne bacteria. Cuttnres tlturefrom and from kidnejs 
confirmatory. 

Itsbould be noted that while these German swine-plagiie bacteria 
were fatitl after sabeataneous iiiocnlatiou, the only cultures of the 
American variety which killed swine after such iuoculatiou were from 
outbreaks I, II, and IX. Even the bacteria from the latter outbreak, 
virulent as they were, failed in this respect iu all but one case.* 

Additional investigations concerning Schweineseuehe were uiade by 
Bleiscb and Fiedelert in 1888-'89. The disease appeared in September 
on a dairy farm, evidently introduced by recently purchased animals. 
It spread among the swine in several different stables, ,eveu among 
those which did not cotue in direct contact with the purchsised animals, 
but were simply placed iu the peus evacuated by the latter. Even after 
the disinfection of two stables the animals put into them contracted the 
disease. The investigations were continued until Febniary, 1889, and 
in all flfty-two animals were examined. The disease had been compar- 
atively mild and chronic ; none of the infected died, and the lesions were 
observed iu the slaughtered animals. 

During life the symptoms consisted of coughing, which increased in 
severity when fresh air entered the stables, diflicult breathing, loss of 
appetite, and emaciation. The temperature fluctuated betweeu 102° 
and 105'' F. The lesions observed in the butchered animals were in 
the main limited to the thoracic organs. The anterior (or cephalic) 
lobes were involved in grayish-red hepatization, which in more ad- 
vanced cases invaded the middle and posterior (ventral and principal) 
tubes, the latter only iu isolated regions. The bronchus always formed 
the central point of the hepatization. As the disease progressed par, 
tial caseation of the hepatized tissue and of the bronchial glands took 
place. The caseous masses did not contain tubercle bacilli. Pleiiiitis 
was found only in advanced cases, pericarditis still more rarely. 

The authors found in practically all cases bacteria, which they 
identify with the bacteria of Sokmeineseuche or swiue plague. They 
were obtaiued both by inoculating rabbits and fowls with particles of 
lung tissue, aud more rarely on plate cultures from the lung tissue 
directly. The bacteria obtaiued are so far as the description goes 
identical morphologically with the bacteria found by Loffier, Schiitz, 
and others. Their effect on rabbits differs in some respects from the 
disease produced by the swine-plague bacteria proper. The disease 

■ Bee p. 74, 
H t ZeitscUrift f. Hygiene, VI (16B9], S. 401-4133. 

^ 1614 •) 




130 



may last from 3 to 13 diiys. An examination of tlie text sliows 
tliat soni« rabbits lived longer, oue 137 ilays. At the point of iiiocuta- 
tiou there ia more or les8 siibcutFaneous purulent inftltratiou with puru- 
lent lyiiipbiiugitis. The liver contained in many cases embolic foci, 
which are described (p. 406) as partiy bnmcbed, partly yellowish- white 
spots fonnd ou the surface and on section, and consisting of a pasty 
mass. A careful examination of the text fails to convince me that 
these embolic foci bad any conneution with the disease. Their descrip- 
tion suggests very strongly cysts oi coceidium ovi/orme in various stages 
of enlargement. Thus a rabbit which died iii 24 hours from an intratho- 
racic inoculation of these swiiie- plague bacteria showed at the autopsy 
"the liver very large, the surface stndded with numerous, projecting, 
yellowish nodules as large as pease, similarly tbe cut surface." The 
coccidia, if such they may have been, are easily overlooked ia cover- 
glass preparations, for the method of preparation and staiuiiig de- 
stroys tbein pretty thoroughly. Moreover, these embolic foci do not, 
according to their report, appear with any regularity iu the inoculated 
animals. 

Another point to be noted in the lesions of inoculated rabbits is the 
absenco of exudative peritonitis or pleuritis, which is a very constaut 
lesion in rabbits inoculated with the American races of swine-plague 
bacteria wben they live more than two days after inoculation. 

While swine-plagne bacteria have little or no effect upon fowls unless 
large doses are injected into tbe muscles, the variety under discussion 
was virulent enough to prove fatal to almost all fowls inoculated, 
Death occurred from one day to several weeks after inoculation. In one 
of these " liver emboli " wore observed. One pig which had recci%'ed a 
Pravaz syringe full of bouillon cullnro of these bacteria died iu ten 
hours. The lesions observed were pleuritic effusion, hepatization of 
almost the whole of the right lung. In' the left there were isolated 
ma»ses of hepatization. A second pig which received a snboataueous 
injecttou had a slightly elevated temperature for several days, but it 
recovered subsequently. 

In several diseased pigs there were found ulcers on tbe surface of tbe 
body. In oue a series of caseous cysts, starting from the castration 
wonnd and exteuding along the subperitoneal tissue as far as the um- 
bilicus, was observed. The relation of these lesions to tbe disease is, 
of course, not determinable. 

The authors, after having determined the canse of tbe disease, en- 
deavored to find out how the bacteria are transmitted from one animal 
to another. The swine examined belonged to one tarm and were fed 
chiefly with sour whey. In this whey, taken from the troughs, bacteria 
probably identical with the disease germs were found ou two different 
occasions. Further investigation revealed the fact that while fresh 
milk is not a good soil for these bacteria, sour whey is very favorable 
to their multiplicatlou. The authors therefore explain the transmiasioa 



I 



131 

of the disease by a^sumiug that in the coidiuou feeding trough the bac- 
teria are mixed with the milk.* Some of this accidentally getting into 
the air passages during feeding introduces the disease germs. 

This brief review of the investigations indicates that while the bac- 
teria fonnd by Bleisch and Fiedeler are not hog-cholera bacilli and in 
general the same as swine-plague bacteria, there are some minor bnt 
constant diflerences to which attention has been called. It is a curious 
fact that these bacteria were attenuated with reference to rabbits, bnt 
atill fatal to fowls. Towards the varieties described in this report, the 
fowl, among smaller animals, manifested the greatest and the rabbit 
the least power of resistance. It is not improbable that attenuation, as 
we understand the term, may imply a decrease of virulence as to one 
species and at the same time an increase as to others. It is not unreason- 
able to assume that a variety of swine-plague bacterta, apparently atten- 
nated so far as rabbits are concerned, may still possess virulent proper- 
ties as regards more refractory animals. The properties which make it 
feeble to rabbits and virnlont to swine, for instance, may prove different 
from each other. It is only by such assumption that we can understand 
the action of swine-plagne bacterta from outbreak I anil II, which, 
though attenuated with reference to rabbits, were fatal to swine. 

Avery interesting communication on the subject of swine diseases 
in Germany was recently made by F. Peters, of Schwerin.t During 
the winter of 1887-88 this author examined cases of a diseiise among 
swine which strongly suggests hog cholera. The disease is described 
in brief as follows: 

Soon after the sucking period is completed, the young pigs lose their 
desire for food and become emaciated. Cough, increased respiration, 
paleness of the mucons membranes, and diarrhea are also observed. 
Towards the fatal close of the disease, which lasts from 3 to 6 weeks, 
the skin of the ears, the neck, and chest becomes reddened. The greater 
number of those attacked die. In four cases, the large intestine only 
was affected. The description given corresponds closely with the vari- 
ous forms of necrosis, softening and induration commonly called ulcers 
in hog cholera for the sake of simplicity. In a fifth case, in addition to 
the intestinal changes, there were found recent hepatization of the left 
Jung and exudative pleuritis. 

The author made some bacteriological examinations, but they were 
not thorough enough to furnish any reliable information concerning the 
character of the bacteria found. While he maintains that they are 
swine-plague bacteria the description he gives would equally apply, as far 
as it goes, to hog-cholera bacilli. As the temtory of Schwerin is not 
very far from Denmark, the scene of swine pest {hog cholera] during 
18S7 and since that time, it is not improbable that this region is slowly 
being iuvmled by two diseases, the Schweineseuche, or swine plague, 



132 

fonnd by Schtitz in 1885, and the swine pest, or hog cholera, first noticed 
in Sweden and Denmark in 1887.* This possibility has been suggested 
recently by Bunzl-Federnt in an article devoted to swine-plague and 
closely related bacteria. The problem of infectious swine diseases 
would then enter the phase in which the investigations of this Bureau 
found it as far back as 1886 in this country, in which a mixture of two 
diseases is encountered more frequently than either disease by itself. 

In this summary some articles of minor importance have remained 
unnoticed. Likewise the observations of Eoloff f on caseous changes 
in the intestines of young pigs have been passed by because they give 
us no information as to the nature of the bacteria involved in the 
disease. The views of some that his cases were swine plague, of others 
that they may have been hog cholera, are purely hypothetical. 

* See Special Eeport on Hog Cholera, 1889, p. 181. 
t Arcbiv f. Hygiene, xii, 1891, S. 198. 

t Die Scbwindsucht, fettige Degeneration, Scropholose und Tnberkulose bei 
Sohweinen. Berlin, 1875, 



SOME PRACTICAL OBSERVATIONS ON THE PREVENTION OF 
SWINE PLAGUE, 



The factors which enter into the production of outhreiklis of swine 
plague may be divided for convenience into two classes, those pertaitiing 
to the animal itself, and which make it more or lees snsceptible or insus- 
ceptible to the speciHc bacteria, and those which relate to the bacteria. 
The conditions which make anituaU more susceptible to iufectiou are 
as varied as the conditions which reduce theirvitality. The importance 
of rearing and keeping animals in such a manner as to produce and 
maintain a healthy action of the various functions of the body has not 
been insisted upon with as much emphasis as it deserves, owing to the 
somewhat overshadowing influence which the study of pathogenic 
bacteria lias exerted npon all minds. It is evident, however, that vet- 
erinary hygiene has much to do with the decline of large epizootics, not 
only by keeping away the germs of disease, but by enabling the animal 
body to resist their attacks. Of those conditions of swiue which invite 
disease very little is as yet positively known, and we simply call atten- 
tion to a few to arouse the interest of those who are in position to make 
observations, 

JThere have been iudicatiotts during the course of experiments at the 
Bureau Station that the breed may have some inflnence in predisposing 
to infection. As an illustration we may cite an experiment in vaccina- 
tion of swiue against hog cholera carried on at the Station in 18S9-'90.* 
The vaccination, which consisted in subcutaneous iuoculation of culture 
IiqHid,seem8 to have had DO effect; for, when the time for exposure oame, 
pi'actically all pigs from one lot succumbed and all from another lot 
survived. The latter were Essex grades reared in pons; the former, 
grades of raised Jersey Reds and Chester Whites not raised in pens. 
While it is iiiiirossible to give any facts as to the relative resistance of 
different breeds to swiue diseases, it is a subject which should receive 
the duo consideration of swine-breeders, especially in those Statos 
where swiue diseases are more or less stationary. 

another important element. We have found a decided difler- 
<«nco in the susceptibility to both hog cholera and swine plague in favor 
|of older awine. This element of age is familiar to all with reference to 




184 



itlieria, and I 



^certain human maladies, snch as scarlet fever, meaalea, diphtlie 
^Bomo other diseases which preferably iittack the youug. 

Peeding is jierhaps the most important factor in prediBpositig swine 
Lto disease. The assimilation of large qnaDtities of food and its con- 
['version into fat seems to be the one essential function of swine. This 
L goes on to such a degree as to lead to pathological conditions after a time, 
I Not only the ingestion of large quantities of food, bnt of one kind for a 
' long time, is iu itself opposed to the habits of such omnivorous animals. 
Besides overfeeding upon one kind of food we have the uncleanly snr- 
ronndings in which swiue are apt to be kept contributing materially to 
a reduction of vitality. 

In addition to the unhealthful modes of existence to which swine are 
subjected, and partly springing from them, are certain pathological con- 
ditions induced by parasites of different kinds. The life history of some 
of the more important parasites infesting swine is still to be elucidated. 
As a rule, we have found in onr post-mortem examinations a larger 
number and variety of internal parasites in those herds which have 
been allowed to run freely than in those brought up in pens. The op- 
portunities for infection seem to be much greater in the former case 
than in the latter. 

As to the damage done by parasites it is difficult to form an accurate 
estimate from ordinary observation. Obvious damage may be done in 
the air passages by lung worms (strongi/lus paradoxus) and in the small 
intestine by ascaris and eehinoyhynchiis. The lung worms may be 
met with in all seasons of the year in swine up to 3 months old. They 
invariably inhabit the terminal portion of the two large bronchi of the 
principal lobes. Here there is generally a partial or total occlusion 
of the bronchus for 1 or 2 inches from the caudal border of the lobe, 
due to the lung worms and the enveloping mucus. In some cases thu 
occlusion is followed by collapse and broncho-pneumonia of the lobes 
supplied by the bronchus and its branches. The hepatized lung tissue 
assumes a bright or pale red color, When the lung worms are very 
abundant larger branches of the same bronchus become filled with 
these parasites and the broucUopneumonia may extend over a greater 
portion of the principal lobes. That Inngs in this condition are more 
susceptible to the invasion of swine-plague bacteria wUl be generally 
admitted. The bronchitis begun where the lung worms mature may 
extend after a time into the other air tubes. In outbreaks VII and 
VIII lung worms were found in almost every animal examined. 

K Another question arises with reference to lung worms as the possible 
bearers of the bacteria into the lungs. This will not be answered until 
more is known of the life history of these parasites. Meanwhile the 
evidence would hardly support the opiuion that they may introduce the 
virus. The pneumonia usually begins in the small ventral lobes and 
travels from them while the lung worms begin their injurious work is 
the principal lobes farthest removed from the ventral lobes. All that 




135 

Foan be said is that tliey may make the Inngs more susceptible to tlie 

p disease. 

Id the iatestines ascarides are uot infrequently found extending into 
the common bile duct from tlie duodennm. Some even enter the gall- 
bladder, while others imbed themselves in the ducta conjing from the 
various lobes of the liver and completely obstruct thp flow of bilo. The 
echinorhpnchtts is well known as attaching itself to the mucoim mem- 
brane of the small intestine, and producing ulcerous depressions simu- 
lating those of hog cholera. 

I That there may be other predisposing causes at certain seasons of 

t'the year, such as obscure malarial diseaises dne to protozoa, the inva- 
sion of the muscular system by paorospermia, trichinic, etc., needsiiriply 
to be mentioned, since no positive evidence is at hand. 

The important factor in the produetiou of swine plague (and hog 
cholera as well) bearing on the bacteria ia their virulence. We have 
seen in the chapter on the pathogenic action of swine-plague bacteria 
that their virulence or disease-producing power is snbject to consider- 
able variation, and that they may be very virulent as obtained from one 
outbreak and much less so from another. It may be laid down as a 
general rule that the more virulent the bacteria the more severe the 
resulting epizoiitic, and the greater the mortality. While a more attenu- 
ated variety of bacteria may spare the older and more hardy animals 
of a herd, these will succumb to a more virulent variety. Just iiere 
the facts presented under the preceding head show their importance. 
Attenuated or weaker varieties of swine plague may attack the young 
and the badly kept swine, those infested with parasites and those of 
poorer breeds, while the stronger may not become diseased. This may 
explain also why some lierds of swine are destroyed and neighboring 
ones escape, although both may have had the same opportunities of 
infection. 

The appearance of an epizootic depends thus upon the condition of 
the herd and the relative virulence of the bacteria. While there are 
bacteria whose virulence is sufticient to sweep away every obstacle, we 
are convinced also that much disease due to attenuated bacteria could 
be counteracted by a more hygienic breeding and rearing of swine, 



I "We have seen in preceding pages that besides the particular herd in 
which swine plague exists as an epizootic, bacteria uot distinguishable 
from those of swine plague are found widely distributed in the air pas- 
sages of healthy swine, and of other domesticated animals, such as 
cattle, dogs, and eats. Are these bacteria capable of producing disease 
in swine at any time and therefore a contiuual source of danger, or are 
they harmless ? This question can not bo answered dotlnitely in the 
present state of knowledge on this subject. As a rule, the bacteria 



136 



fonnd in healthy animals belong to more or less attecnated varieties and 
are most likely incapable of prodnciug disease excupting when the con- 
dition of the animals is very poor. Sporadic disease \a snch debilitated 
animals is not contagious and does not spread to other animals of the 
herd tuiless all are in equally rednoe<I condition. It may happen, how- 
ever, that such swine plagae bacteria, which live in the air passages of 
older swine as survivals of former esiwsore and disease, may become 
dangerous to young pigs. Of this possibility outbreak VIII may serve 
as an illustration. The litter of young pigs died of swine plague 
caused by a considerably attenuated variety of bacteria, such as may 
be found in apparently healthy swine of greater age. It should also 
be remembered that even older swine, which have been through the 
fattening process and are, commercially speaking, in the best conditiou, 
are really in an abnormal or a pathological state, and, therefore, may 
be more or less susceptible to infection. 

We have shown that there are herds of swine from certain farms en- 
tirely free from jiathogenic bacteria, and the question arises, What ia the 
sbiirce of those swine plague-like bacteria fouud in the upper air pas- 
sages of many herdst I am inclined to think that they are transmitted 
from older swine to younger ones, producing disease only under aggra- 
vated conditions in isolated cases, which disease does not spread to 
other finiuials. 

When we come to the more virulent varieties, those for example, 
which destroy rabbits within 16 hours after inoculation, the case is 
entirely diflorent. Their presence is probably never manifested ex- 
cepting by disease, and it is against the introduction of these bacteria 
that the swine-breeder must protect himself. Such bacteria always 
come from some outbreak of disease directly or indirectly. Let us con- 
sider briefly through what agencies such bacteria may be introduced 
into a herd. 

In the report on hog cholera and in the present volume it was pointed 
out that swine-plague bacteria are far less hardy than hogcholera 
bacilli.* The former perish rapidly in water and in liquids nnsuited to 
theirmultiplication. They survivedryiugfora few days only. In gen- 
eral, they speedily disappear alter thoy have left the body of diseased 
swine, and it is highly doubtful whether they would survive a month in 
the soil or in pens. Such agencies as streams, manure, etc., which may 
distribute hog-cholera bacilli over considerable distances are of re- 
stricted importance in swine plague. The chief danger lies in contact 
with diseased or infected swine. Intermediate carriers of infection cau 
only act for a short time, while swine may harbor disease germs for 
months in localiited inflammations, such as abscesses nnder the skin and 
in the joints, and it is possible that they may vegetate on the mucous 
membranes of the air passages much longer, 

• See table, p. W. 




Swine must tliusbe regarded as tlie chief veliiclo of infectiou. This 
may be conveyed directly from diseased to Lealtby animals; it may be 
nveyed by tbose which have passed through the disease, and hence 
by older to younger swine. It is safe to assume that any swine which 
, have at anytime been exposed to swine plague (or hog cholera) are 
liable to couvey the disease, because we do not know when the specific 
diaease germs leave the body. 

Other sources of danger are railroads leaviirg fresh manure in diifer- 
ent places, the vicinity of slaughter-houses, rendering establishments, 
or any places where the viscera of swine may be scattered or where 
numbers of living swine are temporarily housed, If we bear in mind 
the wide distribution of infectious swine diseases it is easy to believe 
that in any large herd of swine collected from dilferent localities there 
are always some diseased or infected, It is essential, therefore, in 
guarding against disease, to look with suspicion upon all swine the 
, history of which ia not known to soraeextent at least. 

There is a practice current in some parts of the country, and well 
, illustrated by the history of outbreak IX, of gathering together herds 
1 of young pigs from various localities through the intervention of deal- 
In regions where swine diseases are prevalent much of the time, 
1 and where the virus never dies out, this is a specially dangerous practice. 
While swine may not be visibly diseased, or may simply appear some- 
[ Trhat unthrifty, they still may carry the seeds of a virulent outbreak 
t within them which need a little time to gain the required momentum. 
I The mild character of a disease in any one animal is no evidence of the 
. character of the germ. For this mildness may be due to a very viru- 
k.Ieot germ acting upon a highly insusceptible animal and causing a 
I more prolonged chronic disease. In fact, these partly insusceptible ani- 
i mals are the most likely to appear in the markets because they are the 
remnants of herds destroyed by disease. We have frequently been able 
L to demonstrate by experimental inoculations the general accuracy of 
I these statements. Thus bacteria obtained from inoculated cases which 
> had asfliimed a more chronic course had not lost any of their virulence. 
In experiments bearing on vaccination we have been able to increase 
the insusceptibility of rabbits aad guinea-pigs so that virulent bacteria 
produced only a mild form of the disease, prolonged from days to weeks 
nnd eveu mouths. Yet the bacteria cultivated from such cases and in 
jected into animals not vacciuated showed nu loss of virulence. Again, 
we have found swine-plague bacteria in apparently healthy swine inocu- 
lated two mouths previously, and in case of hog cholera we have found 
I the bacilli in the organs of swine 6 to 7 months after apparently uu- 
Lsuccessful inoculations. These bacteria possessed tlie original viru- 
r leuce. 

The question has frequently arisen in the course of these investiga- 
tions whether the bacteria are ever introduced into herds in the food. 
This involves another question, whether hog-cholera or swiuo-plague 




I 



138 

bacteria do exist indopondeiitly of diseased or healthy animals. As to 
both kinds of disease germs there is no evidence that they live outside 
of the animal organism, except temporarily, and that if the food happens 
to be infected the infection has couie from animals directly or indirectly, 
and that it is simply a question of time whethor such infection is still in 
a living condition or not. Food, however, may be infected with other 
pathogenic bact«ria which may become dangerous in producing second- 
ary and perhaps fatal lesions in animals already diseased. This applies 
more directly to the swill food which is used by many in the vicinity of 
large cities and which is composed of such miscellaneous material partly 
in a condition of fermentation and decomposition that the presence of 
disease germs may be considered probable at anytime. Id outbreak 
IX, in which swill food was mainly used, the bacilli of malignant <edeina 
were obtained from some cases and very likely added to the fatality of 
the outbreak. 

3. THE RELATION OF HOG CHOLERA TO SWINE PLAGUE.* 

Throaghout this re|)ort frequent reference has been made to bog 
cholera because many outbreaks studied duHug the past five or six: 
years were mixtures of both diseases, and it is therefore difficult to sep- 
arate them in order to estimate correctly the damage done by each. 
We have encountered a small number of outbreaks, of which some were 
jflue to bog cholera, others to swine plagne, but the majority were the 
result of a mixed infection. 

The outbreaks of hog cholera not complicated with swine plague were 
generally of a virulent type. When both diseases showed themselves, 
neither was, aa a rule, of any great virulence. To explain the frequent 
intermingling of those (bseases we must refer to the bacteriological re- 
sults of the past few years. Besides the virulent varieties of hog-chol- 
era bacilli, which produce a characteristic fatal disease in rabbits after 
subcutaneous inoculation of exceedingly minute doses, we have encoun- 
tered about half a dozen varieties whose virulouce was much diminished. 
The diminishing pathogenic power is shown by the absence of a fatal 
disease after subcutaneous inoculation of rabbits, and even small quan- 
tities of culture liquid injected into the circulation may produce only a 
mild disease. In one t there seemed to be no virulence loft, and it 
becomes questionable whether such bacilli can be regarded aa hog- 
etiolera bacilli at all. The attenuated bacilli have likewise very little 
.■or no effect on swiue. 

Parallel to this diminishing scale of virulence of hog-cholera bacilli, 
.ffehave a similar scale among swine-plagae bacteria repeatedly set 
Ibrth in the precediug pages. Ou the one hand, some varieties will 
destroy rabbits within l(i hours alter inoculation of the minutest trace 
'Of cnltare material into the skin; on the other there are varieties 
■Trhichbarely destroy rabbits after largedoses have been injected directly 

w also pp. 102-108, t Bacillus Xi outbreiik LX, p. 78. 



139 

into the circulating blood. All of theae varieties have been obtained 
from the iuterual organs of diseased swine, and hence even the very at- 
tenuated ones may Lave had some share in the disease. 

If we picture to ourselves a wide distribution of these several varie- 
ties of hog-cholera and swiue-plagae bacteria in the bodies of diseased 
and of partly recovered swine, and, in case of swine-plague varieties, 
in the air passages of healthy animals, it is not ditticult to understand 
why there are so many mixed outbreaks. The practice already alluded 
to, of purchasing pigs from many herds and localities and bringing them 
together to be fattened as one herd, is the most successful method of 
bringing various grades of pathogenic bacteria together and of pro- 
ducing a mingling of two diseases. These mixed outbreaks may de- 
velop in other ways also. The disease may begin as hog cholera and 
become subsequently complicated with swine plague or the reverse 
may be true ; the disease may begin as swine plague, and become com- 
plicated with hog cholera. In either case the most virulent variety 
will probably start the disease, and any attenuated hog-cholera or swine- 
plague bacteria, which are latent iu some of the animals of the herd; 
or have not yet been killed out of the soil, and the surroundings from 
a former outbreak may start into activity and thus produce a more 
fatal mixed disease. It is evident that such secondary attacks of atten- 
uated bacteria would not take place if the animals had not been weak- 
ened by the primary disease. This may be the only way in which the 
great majority of the swine-plague bacteria in the air passages of 
healthy animals can exert any pathogenic effect whatever. It is like- 
wise difficult to understand how attenuated hog-cholera bacilli cau act 
without assistance from swine plague. These statements may be illus- 
trated by referring to the investigations. Thus in outbreak IV" the dis- 
ease was evidently swine plague at first, and complicated with hog- 
cholera later. For the hog-cholera bacilli were only observed in the later 
cases. It should likewise be borne in mind that in swine plague some 
cases are usually of a more chronic type. The disease lasts some time 
and is associated with caseous changes in the lungs. Any hog-cholera 
bacilli have thus abundant opportunity to enter the weakened organism 
andappearafterdeatli in cultures from the internal organs. For the same 
reason hog-cholera outbreaks characterized by very feeble pathogenic 
activity of the hog-cholera bacilli, and hence of a more prolonged dura- 
tion and chronic character, are usually complicated with swine plague, 
because the latter, even though of a feeble activity, has been able to in- 
vade the weakened organism and has had time to do so. In virulent 
outbreaks of either disease death may ensue so rapidly that no invasion 
of the other disease takes place. These statements presuppose, of 
course, that both kinds of bacteria exist in the surroundings of the herd. 
The appearance of mixed outbreaks due to bacteria brought by dif- 
ferent herds is suggested by outbreak VII. Even after a very thorough 
examination of Nos. 1 and '2 no hog-cholera bacilli could be found. In 
|-tbe subsequent cases in which they were present, tboj •«itt'i \fcA(JSN.-j ^"e.- 



140 

tected in the varioas organs examined. Moreover there was quite a 
difference observable in the lesious of the various cases corresponding 
more or less closely to the nature of the bacteria found. The supposi- 
tion already presented in regard to this outbreak was that the hog- chol- 
era bacilli were either present in the locality into which the pigs were 
brought or were carried by some one or more pigs in tlie herd. 

Hog cholera and swine plague thus mutually assist one another to 
produce those feebly infectious, chronic diseases which are common at 
all seasons of the year, and it is not unreasonable to suppose that from 
such apparently insignificant diseases large epizootics are developed, 
which by a gradual return of virulence iu the bacteria, and under slight 
provocations of forced feeding, cold, or other debilitating influences 
on the part of their victims, burst forth at certain seasons of the year 
with unexpected violence.* 

This condition of things refers more particularly to localities where 
swine-raising has been conducted on a large scale, where these dis- 
eases never actually die out, and where consequently the specific 
bacteria are always on hand. In those regions which are being invaded 
by these plagues anew the latter may smolder for several years by 
reason of the introduction of attenuated varieties before they break 
out as genuine epizootics. 

There are no facts at hand to indicate any difference in the distribu- 
tion of these two plagues. The localities where either one or both 
plagues have been determined by bacteriological investigations may 
be tabulated as follows: 



Locality. 



By tlie Bureau of Animal Industry : 

DiHtrict of Columbia, numerous outbreaks 1885-'90. 

Maryland, various outbreaks 1 885-'90 

Virginia, various outbreaks 1885-'90 

Nebraska, 1886 

Illinois (Geneseo), July, 1886 

Illinois (Sodorus), September, 1886 

Iowa, December, 1886 

Iowa (Mason City), November, 1888 

New Jersey (Jobuson burgh), October, 1887 

New Jersey ( Pleasant ville). July, 1890 

Missouri (Chillicothe), 1890-'91 

Nebraska (188G-'88), by Billings 

Maryland (Baltimore), by Welch and Clement 

South Carolina, by Bolton 

II linois, by Burrill 

Massachusetts (near Boston), by J. A. Jeffries 



Character of plague. 



Hog cholera. 

...So 

...do 

...do 



Hog cholera. 



*(?) 

t(?) 

(?) 

Hog cholera. 

...do 

.. do 

...do 



Swine plague. 
Do. 
Do. 

Swine plague. 
Do. 
Do. " 
Do. 

Swine plague. 
Do. 

o . <*> 
Swine plagne. 

Swine plague. 
Do. 



* The investigation in Iowa did not bring to light any hogcholei-a bacilli, though the lesions sug- 
gest the presence of attenuated forms not accessible by the usual methods. 

tin this small outbreak bacilli closely resembling those of hog cholera were found in the spleen. 
Their virulence, however, was very feeble. Subcutaneous inoculation had no effect on rabbits. 



* A cnrioas instance of this recradescence of apparently enfeebled viras is ontbreak 
IV referred to above. During February and March swine plague from a neighboring 
farm became mingled with hog cholera in an infected pen on the Station in which this 
disease had apparently lost all virulence. The cases of mixed disease were of bat 
slight severity so far as hog cholera lesions were concerned. Gradually towards 
spring, animals placed iu this pen died rapidly of hoinorrhagic hog cholera. There 
was no evidence of the introduction of another bacillus, nor were any changes detected 
as regards the bacteria iu cultures or in the inoculated rabbits. 



The question whether the different fspecies of domesticated aiiiiiialB 
on a farm may take from or transmit to swine the disease which we 
have been considering ia of very great importance in view of the chang- 
ing conditions of live-stock interests which are going on in different 
directions in various parts of onr country. 

The problem may be stated as follows: Has the bringing together 
of tlifierent species of animals for the purposes of feeding, etc., on the 
same ground, a tendency to increase disease in one or the other species I 
Will swine take swine plague from cattle and will they transmit it to 
shee[) and horses, for example, or is the reverse ever observed 1 

Investigations and observations during the past 13 years lend some 
color to such possibilities, and it becomes necessary at least to call at- 
tention to those engaged in raising and keeping farm animals to what 
has been determined in this direction, and to arouse their interest in 
the investigation of outbreaks of swiue plague, especially as regards 
the immediate causes. 

In the summer of 1878 there appeared in three royal game preserves, 
in the vicinity of Munich in Bavaria, a very fatal epizootic among the 
wild boars and deer, of which 2-34 boars and 153 deer perished.* lb 
wasalso noticedthateven after the plague in the parks had apparently 
died out, disease among cattle in the neighborhood appeared, and this, 
according to the observations of veterinarians, was identical with the 
disease observed among the game in the parks. 

The disease was very acute, lasting from 12 to 36 hours in the major- 
ity of cases. In those in which pneumonia and pleuritis were present the 
disease may have lasted 5 or (i days. Thechief lesions among the latter 
were croupous pneumonia, pleuritis, pericarditis, and mediastinitis. 
In cattle the disease appeared in two forms. In one a swelling was 
observed on the head, the face, the neck, or in the tongue, which as- 
sumed enormous proportions inG to l^hoursandledto suftbcatiou. The 
swelling was due to serous or serous and hemorrhagic infiltratiou. In 
the other form, in addition to the pneumonia, pleuritis, and pericarditis 
observed in the game, there was always i)re8ent a severe hemorrhagic 
inftammation of the small intestine. Bollinger called these forms exan. 
thematic and pectoral, respectively. At this time bacteriological meth- 
ods were still undeveloped, and nothing is known of the nature of the 
bacteria causing this outbreak save the fact that they were not anthrax 
bacilli. A number of inoculations were made upon various animals, 
which testify to the extreme virulence of the specific bacteria. 

Babbits died 6 to 8 hours, sheep and goats 30 to 36 hours afterinocu- 
latioD. Two old horses died after subcutaneous inoculatiou with blood 
from cattle in a very short time. A young steer, 1^ years old, was fed 

H * Bollinger. Uber oiue none Wild- und liiniletseacha. Miiuuhea, 1878. 



J 



142 

with a thimblefnl of the intestiniil contents of a calf wbicb bad snc- 
Climbed to an enormous Bwelling. The steer died in 54 hours with 
pneumopia ami plenritis. A pig inoculated siibcittaueously over the 
left shoulder with a few^ drops of blood died in 22 hours. Besides an 
extensive erysipelatous swelling startiug from the point of inoculation 
there waa beginning fibrinous pleuritis. 

The disease reappeared in the following years, either sporadically or 
in restricted outbreaks. In 1879 and 1880 it was observed among 
domesticated animals alone; in 1881 among tbe animals in the game 
preserves. In 1S85 Kitt* published some investigations which were 
destined to throw more light upon this new plague. With blood from 
an outbreak among cattle resembling the epizootic described by Bollin- 
ger, Kitt made some inoculations upon small animals. Uf mice, rab- 
bits, gniuea-pigs, and oue pigeon inoculated, the mice and rabbits died 
within 24 to 36 hours, the pigeon iu 36 hours. The guinea-pigs were 
not affected. Lesions were in general absent. The blood contained 
large numbers of bacteria. Subseiiuently the spleens of an ox, a young 
pig (of which eight had died), and a horse which had succumbed in the 
same locality, showed on microscopic examination the same bacteria, 
whose virulence tested on rabbits was likewise the same. In a cow in- 
oculated subcutaueously over the left shoulder an extensive inflamma- 
tory oedema of the inoculated shonlder appeared, which extended over 
the entire left limb. The swelling later became converted into an 
abscess, but the animal did not die. 

Of special interest is the subcutaneous inoculation of a pig with a 
minimum quantity of mouse's blood. From the place of inoculation on 
the right thigh a bluish discoloration of the skin spread over the whole 
body in spots and patches, while there was considerable swelling at the 
place of inoculation. The pig was dead in 24 hours. The autopsy re- 
vealed, iu addition to the lesions mentioned, exudative pleuritis and 
peritonitis, congestion of the mucous membrane of the upper air pas- 
sages and of the stomach. A goat inoculated su be u tan eon sly in the 
same manner was afflicted with extensive localinflammatorT oedema and 
died within 2 days. A horse inoculated subcutaueously in the neck 
with a suspension from an agar culture, derived originally from the 
mouse, died withiu IJ days with extensive local reaction, fluid blood, 
ecchymoses on heart, pleuritis and pericarditis, and beginning inflam- 
mation of the mucosa of the stomach. 

The bacteria found by Kitt have a marked resemblance to swine- 
plague bacteria, and their pathogenic effect on pigs and smaller animaU 
is identical with that of very virulent swine-plague bacteria. Kitt 
states that they grew upon boiled potato as grayish-yellow colonies, 
whereas swine-plague bacteria do not produce any visible growth. An 

' Uebercine e\ peri men telle, der Rinderaenche (Bollinger) jibnliobe lafectioDBkrank- 
lieil. Sltzungaberichte der GesellscbafC f. MorjibologieuDdPhjeiologieinUiiDcfapo, 



^ 



143 



examiiiatiou of the text leads us, however, to believe that lie inoculated 
potatoes directly with blood. TLoso who have made many cultures 
of these bacteria have undoubtedly realized how very richly cultures 
have grown to whlcli a little blood was transferred from the animal 
under esaniiuntion. Hence the potato growths were likely due to the 
presence of blood. The further statement that, after an examination of 
Kitt's cultures, Schiltz considered these bacteria different from those of 
Sckiceineseuehe (swine plague) because the latter did not kill pigeons is 
worth nothing, because the differeuceis simplyamatter of virulence. The 
great difference among swine-plague bacteria themselves as regards this 
veiy point we have repeatedly pointed out. 

A disease probably identical with the foregoing was described by 
Create and Armauni,* as occurring among herds of young buffaloes in 
Italy. The disease appears very suddenly, and the animals attacked 
may die in from 12 to 24 hours. The symptoms are high temperature, 
rapid and feeble pulse, discharge of mucus from nose and mouth, asso 
ciated with a local swelling on the head and face which leads to suffo- 
cation. The lesions observed after death are few and inconstant, a 
hemorrhagic inflammation of the small intestine being Ixequently ob- 
served. TLe specific bacteria seem to be identical morphologically with 
swine-plague bacteria. The disease can be reproduced iii young buffa- 
loes by inoculation of cultures. It was similarly produced in a colt, a 
cow, a sheep, and in mice, rabbits, guinea-pigs, pigeons, and fowls. 
DeatL ensued in all animals in from 1 to 3 days. Of two young pigs 
inoculated one died, the other survived. 

in France, Galtiert has found pneumo-enteritis of swine associated 
with a similiar disease in sheep which came in contact with them. 
While there is much in favor of his assumption that the infection passed 
from the swine to the sheep, the description of the specific bacteria aud 
of the methods of inoculationarenotsufficiently complete aud thorough 
to bring conviction as to tLe transmission, or furnish any definite in- 
formation concerning the nature of the bacteria found. A few sugges- 
tions thrown out here and there are sufficient, 1 think, to permit us to 
exclude hog-cholera bacilli and regard them as belonging to the group 
under consideration. 

These various investigations are of great importance io showing that 
some infectious diseases may either attack several species of domesti- 
cated animals at the same time, or be inoculable from one species to 
another. What is of special significance in the first two investigations 
is the extreme virulence of the bacteria. The same maybe said of the 
Italian buffalo disease. 

There is another class of infecti ons diseases, due to bacteria of the 

• Atli i3el R. Istituto d' incoraggiameDto alio Bcieni'.e naturali, etc., 18S7. For a 
brief account, soe also Journal de Miidecine V^t^rinaire, 1887, p, 565, and BanrngfuE.- 
Jbu'b JahroBbericht for 1887, S. 134. 
_ Uoarnal de M£d. V6t., 1S89, paeHm, 



ted 1 



J 




I 



144 

gronp, wbich produce specific diseases among certaia species of 
domesticiLteil aciuials, bat which diseases are Dot koown to be com- 
manicable to other species. AmoD^ these are fowl cholera, rabbit septi- 
cemia, and a pecaUar form of pleuro-pneanionia in cattle, which Poels 
has called " septic plenro-pnonmonia." Daring the past 3 or 4 years, 
the writer has examined in the latioratory of the Bureao of Animal In- 
dustry a small Dnuiber of lungs from cattle all'ected with pneumonia 
Jram which bacteria pi-actically identical with swine-plague bacteria 
■were isolated. A description and discussion of these forms of pnea- 
monia iu cattle will be reserved for a future report. 

There is thus a wide distribution of diseases among dorueslicatecl 

Animals due to a gronp of bacteria closely resembling and probably 

identical with swine-plagno bacteria. Some diseases attack several 

species at the same time ; others are, so far as we know, restricted to one 

s|iecies. We have alsoseen that there is a wide distribution of attenn- 

ated varieties among the same domesticated animals in the healthy 

state, inhabiting, so far as our investigations bavo gone, the upper air 

^^ passages. Some observers are inclined to regard these different bac- 

^^L.teriaas practically the same. Hiippe has proposed the name septicatnia 

^^B Jtcsmorrliagica for all the forms of disease caused by them. Other ob- 

^r gervors hesitate to accept at present this unifying explanation. For 

practical purposes the following explanation, based on quito estende«l 

study of this group of bacteria, may serve as a prorisional guide in the 

prevention of disease. 

The real test of the power of any bacteria to produce disease is viru- 
Icnce. The greater the virulence the more liable will be the disease lo 
spread from one species to another. This is strikingly illustrated by 
the Wilti»evc?ie of Bollinger. The relative virulence can be accurately 
determiucd only by careful series of inoculations upon small and large 
experimental animals, performed iu precisely the same way hi each case 
with pure cultures of the bacteria. Again, the power of a given disease 
to pass from one species to another frequently remains unnoticed, partly 
because the opportunity for such trausmissiou is rarely given. Animals 
of different species, such as swine, cattle, and sheep, are rarely raised 
and kept in the same inclosures, because the nature of food required 
for each, and other conditions lead to specialization iu stock-i'aising 
and tend to restrict each species to its own pasture ground. 

It is not unreasonable to suppose that bacteria livingin the air pas- 
sages of one species, and harmless to it to a certain degree, may prove to 
be disease germs with reference to another species. Thue the attenu- 
at«d bacteria living iu the air passages of healthy cats, dogs, pigs, and 
cattle, are all fatal to rabbits. In general, the larger and more powerful 
the animals the less effect disease germs have upon them. It is there- 
^ fore probable that some of the outbreaks of swine disease in the West- 1 

^^ ern States may be due to the cattle with which the swine are herded ] 

^^■iiar feeding purposes. The bacteria in cattle, harmless to them, or per- J 




145 

haps causing only mild disease and rarely observed, may prove tlie start- 
ing point of disease for swine. 

While webavo no poaitive demonstration of these statements, it is 
desirable tiiat those eiigiLged in stock-raising should have their atten- 
tion called to the possibilities embodied therein. 

5. ON MEAStfURS TO BE TAKES IN THE PREVENTION Of SWINE PLACiUE. 

In regard to the general measures to be taken and the rules to be 
observed in the prevention of liog cholera and swine plague, we refer 
the reader to the report of the Secretary of Agricultnre for i8S3, page 
156, or the report of the Bureau of Animal Industry for 1887-88, page 
148, or the Special Report on Bog Cholera, 1889, page 123. The rules 
and directions there formulated are adapted a» well to swine plague, for 
the bacteria of the latter disease are even more easily destroyed by vari- 
ous agencies thau are hog-cholera bacilli. In the following pages only 
the most important points are touched upon. 

The things with which healthy swine should not come in contact are, 
in the order of their importance, first of all, diseased herds and ani- 
mals, strange swine the history of which is not known, oflal from estab- 
lishments using carcasses of swine, recently infected ground, railroads 
carrying swine, and polluted streams. Soil and water may be infected 
by living and deatl swine or any oftal from them. 

When the disease has actually appeared in a herd the question gen- 
erally arises whether it is worth while to make any attempts to save a 
portion of the herd or to leave them to their fate. As a rule it may be 
stated that it is best to slaughter both healthy and diseased at once and 
give the snrroundings sufficient time to rid themselves of the infection 
before fresh animals are brought into them. If this be not desirable we 
should recommend the following measures to be rigorously carried out: 

(a) Removal of still healthy animals to uninfected grounds or pens 
f_as quickly as possible. 
K (b) Destruction of all diseased animals. 
" (o) Careful Inirial or burning of carcasses. 

{d) Repeated thorough disinfection of the infected premises. 

{e) G-reat cleanliness both as to surroundings and as regards the 

food. 

If the animals have been removed to uniufeeted grounds, careful 
watching is necessary to remove therefrom at once all swine which 
show signs of disease. 

Among the various disinfectants which can be recommended are the 
following: 

1. Slaked lime, in the proportion of about 5 per cent (one-half pound 
of lime to a gallon of water). 

2. Equal volumes of crude carbolic acid and ordinary sulphuric acid 
mixed together and added to water in the proportion of 3 
gallon of water (IJ volume per cent). 

L 1014 10 



J 



3. Sulplinrio acid added to \vater iu tbe proportiou of 1 ounce to a 




4. Boiling water. 

5. Oorrosive sublimate (mercnrio cliloride) Id tUu proportion of 1 
draijhm to a gallou of water (1 to 1,(100). 

Solutiou No. 2 18 said to be more active if, while the sulphuric acid is 
beiug added to the crude carbolic aoid, the vessel coiitaitiing the latter 
is placed in cold water to prevout undue heating of the liquid. 

It should be borne in mind that aolphuric acid and corrosive eubli- 
niate attack metals, and that the solutions arc best made iu wootleii 
pails, etc. Corrosive sublimate is also highly poisonous, aud the solu- 
tion should uot be made stronger than indicated. The lime is, on the 
whole, the best and cheapest, but it may uot be desirable to use it every- 
where ; hence, one of the others may be substituted. Each of the solu- 
tions recommended is more than strong enough to kilt both hogcholera 
aud swiue-plague bacteria and they ueed not be increased iu strength. 

Wheuswiuehavebeconieinfected while runuiugover tracts of ground, 
disinfection of such tracts may be regarded as practically impossible. 
If, however, they have been brought up iu pens or iu small inclosures, 
disinfection should be thotoughly carried out. The woodwork of pens 
may be disinfected by exposing all portions, cracks aud corners, to the 
action of any of the solutions mentioned. These may be applied with 
a broom or any other household article which insures uniform wetting. 
Whitewash is useful for woodwork of fences, etc., when there is no ob- 
jection to its appearance. Its action is only exerted at the time of 
application and after it has dried it will uot destroy bacteria subse- 
quently adhering to it. It must, therefore, be applied iresh every time 
disinfection is needed. For large farms some kind of spraying appa- 
ratus would be of great service iu insuring uniform distribution of the 
disinfectant. Iu the selection care mast be exercised, however, owing to 
the corrosive action of some of tbe solutions. The disinfection of the 
surface of the soil over small areas is perhaps best accomplished by the 
slaked lime or the crude carbolic-acid solution. It should be remem- 
bered that both prex>arations may be irritating to the feet of animals 
immediately after they have been applied. The feeding troughs should 
receive special attention, and after the application of the disinfectant 
this should be washed away with water, preferably hot or boiling. 

The directions thus far given apply mainly to the prevention of dis- 
ease. When animals have been actually attacked, can anything be 
done for them T It has already been stated that treatment of commu- 
nicable diseases is uot a desirable thing, but even if it were the deaths 
follow each other so rapidly in many outbreaks that there is no time 
for the application of remedies. If, however, an eflbrt to treat them is 
to be made, it is desirable to avoid the various specifics and remedies 
ofunkaowncorapositiou, some of which, thoroughly tested at the Bureau 
Station by Dr. F. L. Kilborne, were of no avail in checking the disease. 




147 

The BJek aniipals sboald be isolated one from another, as far as poesi- 
ble confined in amall incloaures, kept qaiet, and fed with moderate 
quantities of food, preferably with milk, if this is to be obtained. If 
the swine are being fattened when the disease appears, this process 
should be stopped at once and a light diet subatituted. The tendency 
towards the localization of disease in the large intestine, in both swine 
plague and hog cholera, seems to be due, at least in part, to the cou- 
stipated habits of the pig, which permit the pathogenic bacteria to re- 
main long enough in the inteatiue to act injuriously upon the mucous 
membrane. Constipation is not easily overcome, as the trials with vari- 
ous cathartics'* have demonstrated, and it is highly important when 
the disease has appeared to feed a greater variety iu small quantity or 
to follow the recommendation of giving the digestive organs a complete 
rest by feeding milk. The boiling of food may be desirable, inasmuch 
as it destroys any disease-producing bacteria which may be present, 
and makes digestion easier. An experiment carried out at ti]e Bureau 
Station with boiled food did not show any more favorable results, how- 
ever, than with unboiled food ordinarily given, so that we can simply 
suggest it for further trial- 
Even if treatment should succeed after much trouble and expense to 
save some few swine, it may not be profitable, owing to the injury in- 
flicted on the various organs during the disease. The lungs are, as a 
rale, seriously affected. They may become adherent to the walls of the 
thorax, and the pericardium may become firmly attached to tbe heart 
and impede its action. These permanent injuries, which uo kind of 
treatment yet suggested can avoid, exercise an injurious influence on 
the prosier development of the animal affected and make its raisiug of 
questionable advantage. It has already been stated that such recov- 
ered animals may for a time at least be dangerous as carriers of the dis- 
e.ase germs to other swine. 

The only encouraging line of action, therefore, lies in the prevention 
of disease by the observance of suitable precautionary measures and 
in that general practice of hygienic laws which thus far has been tlie 
only means of checking the rapid spread of epidemics in the hniuau 
family. The method hrst suggested by Pasteur of inoculating animals 
with attenuated cultures, to make them resist any and every attack of 
a given infectious disease, is, theoretically considered, the simplest ' 
means of prevention. Practically, however, there are two objections 
which are growing in importance year by year, as our knowledge of 
infectious diseases is becoming broader and deeper. The method of 
Pasteur may distribute the specific bacteria far and wide and become 
a source of future evil, since we do not know bnt that the attenuated 
bacteria may in some way regain their former virnletice. The other 
objection rests on the fact that diseases differ so much one from the 
other that the method seems to insure success in only a few dis 

* Special Keporb on Hog Cholera, 1680, p. 135. 



148 

Ab regarda swine plaf^ae, the expcrimentR wliicb have thus far 
been earned out imiiiuite ttiat this disease may prove amenable to pre- 
ventive inoculation. We have lieen able, by the injection of botli living 
cultures and those sterilized at a low temperature [HS^ C), to make 
the most susceptible animals, rabbits, insasceptible to the moat virnlent 
swiue-plagne haeteria. B,y two subcutaneous injections of cultnres of 
swine-plague bacteria swine have been made insusceptible to doses in- 
jected into the circulation, which pi-oveil fatal to "control" pigs within 
24 hours. In the preliminary experiments upon rabbits, designed to 
produce immunity, several methods were employed.* 

1. Minute but gradually increasing rinautities of culture liquid of very 
attenuated swine-plague bacteria were injected at dift'erent intervals 
into the ear vein of rabbits. Only a very small proportion of these sur- 
vived the test inoculation with very rirulent swine-plague bacteria. 

2. Sterilized bouillon cultures were injected into the abdomen and 
into the circulation of rabbits. This method also produced immunity 
and partial resistance, but in only a comparatively few animals, 

3. The preceding method was modified in the following manner: 
Swine-plague bacteria from outbreak IX were allowed to produce for 
2 days a rich growth upon agar. This growth was scraped off and a 
very turbid suspension in bouillon prepared and sterilized at 58o C. 
With this sterilized suspension injections wore made into the abdomen 
of rabbits as follows i 



Rabbit No. 


Mar*. 


Mv a. 


May 14, 


Ma, 22. 


Totol, 


H,„„U.. 




1 




S 


K. 


3 


NcH. 3S, 30, and 37 Inoonlnteil witb 
vinilcml nwine plftKne Miiy M. 










Mnv ID, dlu In B day* with asTPra 
local rBacH.m, plonritla, anit port. 







^m The 

H ~^ 

^■^ tSe< 



These results show very decisively the protective effect of the steril- 
ized growth of Bwine-plague bacteria. Additional experiments have 
not yet been matle. 

In conjunction with Dr. Kilborne, the protective effect of swine-plague 
cultures was tested upon swine in the following experiment: Seven pigs 
belonging to the same lot and about 4 months old were chosen, three 
of which were set aside as " control " animals or checks. The remain- 
ing four received February 28, 1891, a subcutaneous injection of 6 cubic 
centimetres of peptone-bouillon culture of virulent swine-plague bac- 
teria {outbreak IX), one-half into each thigh. As a result one died.t 
The remaining three were reinoculated in the same way Mnrch 14, 



Tlieae espcriinentB wore cartietl o 
tSeop. 74 for aatopaj uotes. 



.njui 



ition Willi Dr. V.A.Moore. 



^ 



149 

receiving on this date 10 cubic centimetres of ciiltnre liquid. April 3, 
tliese, together witli tlie tlirce control animals orcheclis, received tlie 
liiial test inociiliitioii ; 2 ciibic centimetres of peptoue-bonilhm culture of 
tlie same bacteria were injecteil into a vein of tUe leg of each animal. 
Two of the control animals died within 2i hours, tlie third in 3C hours, 
None of tlie three vaccinated animals became ill. No symptoms of dis- 
ease or lesions appeared subsequent!;'. 

These esperiments simply demonstrate the fact that swine may be 
protecteil from fatal doses by snbcutiineous injection. Whether tliis 
process wonld be successful in natural outbreaks can not be inferred 
from this test. The method is open to the objection above mentioned, 
i. e., it is liable to distribute the specific bacteria wherever vaccination 
is practiced. Since the more desirable one of injecting the products of 
bacterial growth is now being tested there is no need of any further 
discussion of this subject at the present time. 

COHCLUSIONS. 

I. There are two independent infectious diseases of swine — swine 
jilague and hog cholera — each caused by an easily recognizable, specific 
disease germ. 

3. Swine plague (in those outbrealis which have come to our notice) 
is limited chiefly to the lungs in its destructive effect. Tlie intestines 
may be and frequently are involved in the disease jtiocess. Hence it is 
an infectious pneumo-enteritis rather than an infectious pneumonia. 

3. There is considerable variation in the virulence or disease-produc- 
ing power of swine-plague bacteria from diflerent outbreaks. The 
greater the virulence, other things being equal, the severer and more 
extensive the epizootic. 

4. The bacteria of Schweineseueke (German disease of swine) are iden- 
tical with those of swine plague. 

5. In the upper air passages of a certain percentage of healthy swine, 
cattle, dogs, and cats, bacteria exist which belong to the species of 
swine-plague bacteria, and which as a rule possess a relatively feeble 
virulence. While it is probable that such bacteria may produce disease 
it may be regarded as pretty certain that it is largely aided by second- 
ary causes produciiig unthriftiness, and is merely sporadic and not 
communicable. 

6. lu many epizootics of swine disease both hog-cholera and swine- 
plague bacteria as well as the respective lesions of these bacteria co- 
exist. Such mixed diseases are duo to the frequent presence of both 
bacteria in the surroundings of ewine, probably a result of frequent in- 
troduction. Either disease may be primary according to its relative 
virulence. 

7. It is highly i>robable that the many attenuated varieties of either 
disease germ can produce disease only when assisted by the other germ 



J 



150 

or by the nnsanitary, nnpbysiological methods of rearing swine by which 
the lattiT are rediUHHl in vitality and iniule more susceptible. 

8. It is pretty well established that there are a number of infections 
diseases allectin|j^ cattle, builaloes, deer, fowls, and smaller animals, 
the bacteria of which are closely related, if not identical with, those of 
swine plague. These plagues appear in various parts of the globe spo- 
radically. ( Wild- und RinderseuchCj harbone hufalino, fowl cholera, rab- 
bit septicaunia.) Their tendency to spread from one species to another, 
from c<attle to swine, for instance, i)robably depends both on the degree 
of virulence of the bacteria as well as the opportunities aftbrded for 
such transmission. 

9. Swine-plague bacteria are very probably introduced into a herd 
only in the bodies of animals, since they are speedily destroyed in soil 
and water by natural agencies. Virulent varieties are perhaps always 
derived from preexisting disease. Attenuated varieties may be intro- 
duced by healthy animals. Since these may under special conditions 
give rise to disease, eftbrts to prevent and suppress infection must take 
into account the physical condition of the exposed animals. 



APPENDIX. 



THE PRESENCE OF SEPTIC BACTERIA, PROBABLY IDENTICAL WITH THOSE OF SWINE 
PUfiDE, IN THE UPPER AIR PASSAGES OF DOMESTICATED ANIMAI^ 

OTHER THAN SWINE. 



By Vkranus a. MoorK) B. S., M. I)., Assistant 



The exaraination of the secretions of the mucous nionibraue of the 
upper air passages in domesticated animals other than swine was be^ 
gnn under the direction of Dr» Tlieobahl Smith for the purpose of deter- 
mining whether or not the swineplague germ, or a germ closely related 
to it, is normally present in these animals. The results obtained from 
the limited number of examinations that have been made from the 
various animals are of so much value in throwing light upon the natural 
habitat of this group of microorganisms that a preliminary report of 
these experiments seemed desirable at this time. 

The methods that have been employed in these investigations are the 
same as those used by Dr. Smith in the examination of mucus from 
the respiratory tract of healthy pigs, and which are described on p. 
110 of this report. The inoculations of rabbits with the mucus from 
the various animals were made in part conjointly with Dr. F. L. Kil- 
borne, in part by him alone, and in a few cases I alone am responsible 
for these operations. 

1. Inoculations from cattle, — Rabbits have been inoculated with the 
mucus taken from the larynx or amygdaloid cavities of seven healthy cat- 
tle. Four of these were steers, two of which were Western animals that 
had been shipped to Washington for beef. The four steers were killed 
in a slaughter-house near the Experiment Station bj^ cutting the blood 
vessels in the neck. Care was taken to keep the mouth free from blood. 
The other three were heifers that were killed for various purposes in a 
similar manner at the Experiment Station. In each case the mucus was 
collected immediately after the death of the animal and inoculated sub- 
cutaneonsly into rabbits. 

The rabbits that were inoculated with the mucus from the four steers 
and one of the heifers died in from 3 to 6 days. The leaioua foijcw^L va^ 
these rabbits were similar to tliose pro4\iee>d\>^ \a\vft ^\Xfc\ixxaK56^^^>^^- 



152 

plague germ. The local infiltration contained several forms of bacteria. 
In the peritoneal exudate and in the spleen and liver bacteria were 
found that resembled the swine-plague germ both in stained cover-glass 
preparations from the tissues and in cultures. 

The rabbits inoculated from the two remaining animals showed no 
signs of disease. 

The pathogenic effect of the bacteria obtained from the first two cat- 
tle was determined by inoculating rabbits with pure cultures. The 
subcutaneous injection produced extensive purulent infiltration at the 
point of inoculation and exudative peritonitis, destroying the rabbit in 
6 days. An intravenous inoculation of the same quantity of a similar 
culture from the second case proved fatal in 24 hours. The blood, liver, 
and spleen contained innumerable bacteria which could not be distin- 
guished from the swine-plague germ. No inoculations were made with 
pure cultures from the remaining three animals. It is sufficient to say 
that the lesions produced in all of the rabbits inoculated from the five 
cases were the same. The following tables will explain the results of 
these inoculations : 

Inoculation of rahhits with mticua from the upper air passages of cattle. 



Ani- 
mal 
No. 



1 
2 
3 



4 
5 

6 



Mucus 
from— 



Amygda- 
loid cav- 
ities. 

Larynx ... 

Amyg da- 
loid cav- 
ities. 

. . . do 

. . . do 



Larynx . . . 

Amygda- 
loid cav- 
ities. 



Rabbit 
inocu- 
lated, 
No. 



2 
3 

4 



6 
7 
8 


10 

11 



Dat« of 
inocula- 
tion. 


Rabbit 
died 
in 


1890. 
Feb. 27 


Day». 
3 


Feb. 27 
Feb. 27 
Feb. 27 


4 

4 
4 


Mar. 13 


8 


Apr. 1 
Mar. 20 
Oct. 2 
Oct. 2 

1891. 
Jan. 5 


4 

4 

6 


Jan. 5 






Remarks. 



Local reaction; peritonitis. 

Do. 
Local reaction; peritonitis; plenritis. 
Local reaction ; perit(»nitis ; pleuritis and pericar- 
ditis. 
Local reaction ; peritonitis. 



Local reaction; peritonitis; beginning pleuritis. 
Rabbit remained well. 
Local reaction ; peritonitis. 
Do. 

Rabbit remained welL 

Do. 



Inoculations with pure cultures obtained from above rabbits. 



Culture 
from 
rabbit 
No. 


Method of inoculation and date. 


Rabbit 
died 
in— 


Remarks. 


1 
3 


March 4, 1890, one-eighth cubic centimetre bouillon* culture 

subcutaneously. 
March 4, 1890, one-eighth cubic centimetre bouillon culture 

into ear vein. 


Days. 
6 

1 


Local reaction ; 

peritonitis. 
Septicaemia. 



* All the bouillon used in these investigations contained one-fourth per cent of peptone. 



2..Inoculatio7i8 from cats. — ^Babbits were inoculated with the secre- 
tions of the mucous membrane of trachea, larynx, or pharynx of seven 




I 

1 



153 

Lealtby cata. The cats were raised in aud about WaaliingtoD, but not 
ou tlio Experiment Station. Tliey were killed either by a sbot tliiougb 
tlie heart or with chlofofoinu, and the luucuH was reiiLoved with every 
precaution immediately after death. 

The rabbits that were inoculated from oat No. 6 remained well. All 
of the others died. The result of these inoculations is of particular in- 
terest, as the rabbits died in froml to 7 days, and presented lesions sim- 
ilar to those produced by the awine-plague germ iu its most virulent as 
veil as its attennated forms. From the various organs of all the rab- 
bits bacteria were found which could not be distinguished from each 
other or from the swine-plague germ. 

The virulence of pure cultures obtained from the rabbits inoculated 
from cats I, 2, and 3 was tested by both intravenous and subcutaneous 
inoculations ou fresh rabbits. These proved fatal in from IS to 48 
liours, Ttie blood and other organs contained iuuumerable bacteria. 
The cultural characters of these germs will be mentioned in another 
place. The accompanying tables give a summary of those inoculations: 



Inoeulation of rabbits \Mli n 



n the uppei- air paesagen of to 



?.' 


Ho» killed. 


li^TJ 


s 


Dotoof 
Hon. 


Rabbi b 
died ia- 


l..a.... 


; 


ShDttkrongh 
hcut. 


jLacjux.. 


! 15 

! {! 

1 g 
i li 


18S0. 
Apr. K 
Apr. 22 

Apr. M 

Apr. 22 

June 11 

16»1. 
Jan! 21 


s 

1 
Ik 


Local riwDtiuD ; pBritflnltia, plourl- 

CU. perlcardlUs. 
Local iBBClioD; pBiilonitia. 

SeptlciBinia. 

SIJBbt local reaoUou, bcsiuuiue pM- 

Loeal rBJiBtioni liBBinniueulfliirUlH. 
Loi'.al reaction ; pleurlils. 


...do 


"sr- 


....do 

Chloroforiueil 
....do 


Trai^hfla . 




^ 



laoeulalloiti with, pure cultures obtained from above rabbili 



I 



Culture 
Aom rab- 
bit No. 




IKabbit 


Eamarks. 


15 


May 10, m90,one.Bl(rli 1 h cubic CBntimet™ boQll- 
luu oulturo into ear vein. 

loneullura rjubcutanaoiialy. 


Houri. 
18 


Septicicniia. 

DeglunluH perltJinitis. 

Scpticffimia. 

Slight local reaction ; up- 

S.p™"!n';., 





3. Inoculations from dogs. — Kabbits were inoculated with the mucus 
takeu from the larynx or upper pharynx of six healthy dogs. These 
were also procured iu Washington City and its suburbs. They were 
killed, by a shot through the heart. The mucus was removed imme- 
diately after death and at once inoculated. 



J 



J 



154 

The rabbits inocnlated from dogs Nos. 2 and 3 died in about 36 hoars. 
Innumerable bacteria were found in the various organs that could not 
be distinguished from those obtained from cattle and cats or from the 
swiue-plague germ. The rabbits inoculated from the other four dogs re- 
mained well. Both subcutaneous and intravenous inoculations of fresh 
rabbits with cultures of these bacteria proved that they were as viru- 
lent as those from several of the cats. The results of these inoculations 
are summarized in the appended tables : 



Inoculation of 


rahbils with mucus from 


the upper air passages' of dogs. 


Dog 
No. 


Mucus 
from — 


Rabbit 
inocula- 
ted, No. 


Date of 
inocula- 
tion. 


Rabbit 
died 
in— 


Remarks. 


1 

2 
3 

4 
5 
6 


Tiarynx... 

Pharynx. - 
Larvux . . . 

do 

do 

do 


C 23 
\ 24 
25 
26 
27 
28 
29 


1890. 
Apr. 25 
Apr. 25 
Apr. 28 
May 9 
May 26 
May 31 
Dec. 6 


Hours. 

""'36' 
36 


Rabbit remained welL 

Do. 
Local reaction, beginning pleuritis. 
Local reaction, porilonitis. 
Rabbit remained welL 

Du. 

Do. 



Inoculations with pure cultures obtained from above rabbits. 



Cnltnro 
from 

rabbit 
No. 


Mctliod of inoculation and date. 


Rabbit 
died 
in — 


Remarks. 


25 

26 i 


May 2, 1890, loop agnr cnltare subcutaneonsly in 

esir. 
May 20, 1890, one-eigbtb cubic centimetre bouillon 

culture into ear vein. 
May 20, 1890, one-eighth cubic centimetre bouillon 

culture subcutaneonsly. 


Hours. 
22 

18 

18 


Seplicsemia. 
Do. 
Do. 



4. Inoculations from other animals, — Babbits have been inocnlated 
with the mucus taken from the larynx or trachea of one sheep, one 
horse, two old fowls, and one rabbit. One of the two rabbits inocn- 
lated from the sheep developed a large abscess near the point of inocu- 
lation. It was chloroformed after about one month. There were no 
other lesions. The other rabbits remained well. The inoculations from 
a single animal are, of course, insufficient to give any general informa- 
tion respecting the species. The annexed table gives all the informa- 
tion necessary with reference to these inoculations. 

Inoculations loith mucus. 



Animal. 


How killed. 


Mucus 
from— 


Rabbit 
inocula- 
ted, No. 


Date of 
inocula- 
tion. 


Remarks. 


Sheep 1 . . . 

Horse 1 . . . 

Fowll.... 
Fowl 2 


Cutting jugulars . . 
Shot 


Larynx.. - 
.... do ..... 


C 80 
\ 31 
C 32 
i 33 
34 
35 

36 


1890. 
Apr. 7 
Apr. 7 
Apr. 7 
June 3 
June 3 
June 3 

1891. 
Apr. 


Local abscess; chloroformed. 
Rabbit remained welL 

Do. 

Do. 

Do. 

Do. 

Do. 


Neck broken 

....(10 ............. 


Trachea .. 
....do 


Rabbit 1.. 


Chloroformed 


....do 







155 

It will be seen from the experiments giveu that a germ which ia iiot 
distiuguishiiblG from the swiue-plaguc germ van found in the mucus 
from the upper air passages of 71 per cent, of the cattle, 85 per 
cent, of the cats,.aud 33 per cent of the dogs from which inocula- 
tions were made. When the rabbit lived for more than 24 hours 
after its inoculation there was a purnlent infiltration of the skin and 
snbcutis at the point of inoculation. The infiltration extended over an 
area varying in size in proportion to the leugth of time which the animal 
lived. In some cases it covered the entire ventral aspect of the body. 
Occasionally there was in addition a aanguinolent effusion which ex- 
tended beyond the limits of the infiltration. The local reaction was 
undoubtedly increased by the presence of other bacteria that were in- 
troduced with themncua. The internal lesions were characterized by 
an inflammatory condition produced by the localization of the germs 
on some one or more of the serous membranes, notably the peritoneum, 
when the rabbit did not die from a rapidly fatal septica3mia. 

It is interesting to note that the inoculations made from cattle proved 
fatal in from 3 to 6 days, and that the resulting lesions in every instance . 
were charactaristic of attenuated swine plague. In the rabbit that 
lived 6 days tliere was severe peritonitis, while in three that lived only 
4 days there were both peritonitis and pleuritis and in one case peri- 
carditis. The rabbit which lived 6 days after inoculation with a pure 
culture exhibited in addition to the local reaction only peritonitis. 

In the inoculations from cats we find a much wider range in the char- 
acter of the lesions produced. The rabbits inoculated from oats Noa. 3 
and i were victims of a rapidly fatal aepticiemia, the swine-plague bac- 
teria being distributed iu enormous numbers throughout the blood and 
internal organs. The rabbit inoculated from cat No. 5 lived about 12 
honra longer and exhibited beginning peritonitis. The localization of 
these germs on the peritoneum ia further illustrated in rabbits Kos. 12, 
14, and 15. These animals lived2and 3 days and died with exudative 
peritonitis. In the exudate there were innumerable bacteria, but com- 
paratively few were found in the blood. In rabbit 13 we have a marked 
example of the distribution of these germs over the entire serous sur- 
faces of the trunk. Both rabbits from cat No. 7 are interesting, as the 
lesions were confined to the pleura. In these cases the pleuritic exu- 
date contained inuumerahle swine-plague bacteria while the blood con- 
tained only a few. Thi^ emphasizes the fact that in cases of well- 
niarketl localization there are comparatively few germs in the general 
circulation at the time of death. 

The rabbits that were inoculated from dogs Nos. 2 and 3 lived the 
same length of time as the rabbit inoculated from cat No. 5. It ia in- 
teresting to note that the rabbit inoculated from No. 2 exhibited pleu- 
ritis and the one from dog No. 3 peritonitis- Here again we have a 
marked illustration of the variable localization of this group of micro- 
organisms when their virulence is not sulScient to destroy the rabbit 



in from IS to 24 bourn. The tendency to localization ia well aliown in 
tlie fuUowi'ng Kuniiuury of tlic lesious fouud iu tlie niuetccu rubl)i[s tlial 
Iiavfl succiimbeil to tLe iuoculatiuuH from tbe different animals: 




l™,„.. 


No. or 

rabbit*. 


For OBBt. 




10 



























Ttie inoculations with pare cultures of the bacteria obtained from 
tbe different rabbits, although few in number, are important, as they 
verify the results obtained from the original inoculations. The sub- 
cutaueous inoculation with one-eighth cubic centimeter of a bouillou 
culture of the germ from cattle resulted in extensive local reaction 
and perituuitis. The inoculation of a rabbit subcutaneously in tbe 
ear with a loop of an agar culture from cat No. 1 is also iuteresting, 
as it not only lived nearly as long as the original rabbit, but devel- 
oped peritonitis. The rabbit inoculated subculaneously with a culture 
from eat No. 2 is the only rabbit in these experiments that lived over 
24 hours without exhibiting some point of localization of the germa on 
the serous membraues. 

The difference in the virulence of the germs obtained from cattle, cats, 
and dogs, and the consequent variations iu the character of the lesions 
produced in rabbits, are paralleled in similar inoculations from pigs and 
with cultures of the swiue- plague bacteria obtained from sporadic eases 
and the difterent outbreaks of that disease, I have, therel'ore, not 
found in tbe inoculations of rabbits any pathogenic property possessed 
by any of the septic germs discovered in the upper air passages of 
Iiealtby animals that will differentiate them from the swine-plagnu bac- 
teria. 

Cultural characters. — From the blood or spleen of each rabbit cultares 
were made on agar or in bouillou. From these, subcultures were made 
ia the various culture media employed iu di&ereutiating bacteria for 
the purpose of determining, if possible, any cultural diflerences that 
might exist between them, or between them and tbe swine-plague bac- 
teria. As these cultures were obtained at different times and the media 
used prepared on different dates the occasional slight variations iu the 
character of the growth that were observed between the different bac- 
teria could not be considered as constant differences, as .it was found 
that these bacteria, like those of swine plague, do vary slightly in onl- 
ture media. In view of this fact two series of comparative cultures 
have been made on tbe different media, each medium being x>repared 
from the same material and at the same time. 

Tbe comparative cultures were made (1) from cultures of bacteria ob- 




157 

tained from a healthy pig, cat, and dOR; (2) from cultures of attennated 
and of virulent Hwiiie-plagne bacteria, and (3) from ciiltnreH of swine 
plague bacteria found in a guinea-pig tliat died of sporadic pneumonia. 
Unfortunately the germs from the upper air passages of cattle bad 
perished at the time the comparative cnlturea were made. 

(o) 2fuirieat agar. — -The growths o{ the varlona hacteria upou this aabstratiim wore 
not distinj^aiBbable one from the other. 

(b) Alkaline peptonUed bouillon. -^Tha growth in the boutllou cultures made frum 
the liloud or aploen of a few of the rabhita coaaisted of small, grayish flakes. These 
were at first haldio anapeDaionin the liquid, but soon settled, leaving the supernatant 
cnltnre flmd perfectly olear. This oharacter was not constant, as the oluaipa of 
growth gave way to a tmifotoi oloudiness of the ouUure liquid after a short aeries of 
subcuiturea. The bouillon cultureH from all of tho other rabbits were nniformly 
clonded. 

In the first seriea two of the germs grew in olnmps. The others imparted a uniform, 
cloud inoRS to the liquid. After 7 days standing the growth had settled in the bottom 
of the tube in tbo two cnltnrea that contained clumps, lu the others a tbin, grayish, 
somewhat viscid band composed of bacteria was formed on the sides of the tube at 
the snrface of the liquid. The lattec was fainlly clondeil. The growth of the viru- 
lent swine-plague germ seemed less vigorous than that of the others. In about !1 
weeks there was a eouaiderable quantity of a grayiah, viscid sediment in. the bottom of 
Che tubes which upon agitation was forced up, appearing as a somewhat twisted, tena- 
cious cone with its apes at the surface of the liquid. 

In tbe second aeries the growth iu all of the ou I tures imparted a uniform cloudiness 
to the liquid. In 4H honrs the virulent swine-plagne onltiira was nearly cleared. In 
T days the cultures of the bacteria from the healthy pig and cat and from the guinea- 
pig's lung were clear. The cultures of the atttnuated swine-plague germ and the 
germ from the healthy dog remained clouded. In every case the grayish band formed 
on the sides of the tube at the anrfaeo of the liquid as in four of the cultures in the 
lirst series. The sediment in the bottom of tbe lubes was small in quantity and fria- 
ble. The reaction of all of the cultures was decidedly acid after 34 faours ; less 
strongly ao after 4 weeks. The difference in tbe character of lb o sediment in tbo two 
series of cultures was very marked. Thiaaame variation has been obEerved ia other 
honillon cnlturea of the same hacteria. It is important to add that the variation in 
the character of the growth in bouillon cnlturea of any one of those genns haa been 
found to he as great as tliat between cultnres of tbe bacteria from different sourcos. 

Although these bacteria change the reaction of an ulkaliiic bouillon to an acid 
one during their multiplicatinn, they will not grow when inoculated into peptonized 
beef-hroth that has not heen nentralized. 

(fl) Feplonized bouillon eoHtainiiig 2 per eenl. glucose.— Tho growth of the varioos 
bacteria in fermentation tnbes cootaining this liquid does not vary iu tbe cnlturea 
examined. 

(d) Gtlaline.—The growth in this medinm is uncertain. The germ from cat No. 2 
developed minute grayish colonies in roll cultures. They were, however, too small 
for diagnostic purposes. One of the swine- plague germs occasionally develoiied mi- 
□nte oolouies. The otiier liaoteria did not grow, althaugii a largeuumberuf cultures 
were made from each. 

(e) Potalota. — No growth. 

(f) 3fiii:.— No , appreciable change in the appearance of the milk was produced. 
Slightly acid in reaction. Cover-glass preparations showed a vigorous mnltiplieatioa 
of the bacteria in every culture. In this medium the bacteria appeared as rods 
longer than under other conditions under which tbey have lieen csitmined. 

From both the comparative cultures and tbe large number of cul- 
that have been made at other times, I have thus far been unable 







158 

I to detect any caltaral c&aracter tliat is saffioiently oonstant to differ- 
eotiate the bacteria in question, the one from the other, 

PNELTMONIA AND PLEURITIS IN A GUINEA-PIG CAUSED BY BACTEBIA 
CLOSELY RESEMBLING THOSE OF SWINE PLAGUE. 



Ou December 24, ISDO, a large adult female guinea-pig was found 
dead in a pen where several of the supply anitnala were kept. A care- 
ful examinatiou of this animal revealed the following conditions: 

Beueatli the Bkia oear thu left mamDia a closeil abscLta. Swolliug ftml alceration of 
the left fora foot. Spleen Dorntiil. Liver fatty. No inteiitiiial lesiuuij. In the pleural 
oavitf a coDBiderable qnaatitf of a grayisb, viscid eiadate litiitig the costal and 
pulmoDary pleura. The anterior balf of both luuga hepatixeil. Supporative perj- 
oarditia. Cover-glass propura'ions frum the pleural exuilnto oontained a very large 
namber of bacteria not disting niah able from Bwiiic-plaKue bacteria. la au agar tube 
inoculated with the exadatc a, pnre cultnre of these bacteria doveliiped. 

A rabbit inocalated subcataneoualy with a very amall quantity of the pleural oxo- 

datA died ia leu than 20 hours. Innumerable ewine-plagae baoteriA were fouud 

^ia the liver, blood, and epleen. The polar slain so cliiiracteristia of the swinu-[iliLguB 

genu was well marked in the cover-glass preparationa from all of the tlasnes. A pure 

culture of this germ waa obtaiued from the blood. 

In order to test still further the virolence of thia germ, a second rabbit was iuucii- 
lated anboiitani^ouaty with an equivalent of oue&ve hundredth cubic ceoMitietre of a 
bouillon culture made £rom the blood of the tirst rabbit. This luooulatioo proved 
fata! in about 24 hours. Inunmer.ible awine-plague batiteria were fonnil iu the 
TarJous organs. 

The cultures of this germ on the various media could not be distio- 
guisheil from those of the virulent swine-plague germ. 

Dr. Kilborne informs us that prior to the death of this guinea-pig, of 
which a bacteriological examiuatiou was made, others had been found 
dead from time to time at the Experimeut Station without exposure to 
any disease. A cursory examiuatiou had shown that a considerable 
number of these had died from exudative pleuritis with or without 
pneumouia. 

, DISEASE IN A FOWL ASSOCIATED WITH BACTEBIA CLOSELY RESEM- 
BLING THE FOREGOING. 

Od April 31, ISfll, two large, well-nourished hens were found dead in 
B flock of fowls that are kept on the Experiment Station. A few days 
prior to this a fowl had died, but it was uot esamiued. There bad 
been no evidence of a contagious disease in the dock up to this date, 
and uo deaths occurred subsequent to the ones reported here. A careful 
examination of these fowls showed that one contaiued bacteria closely 
resembling swine plague, and that in the other there was an extensive 
croupous exudate throughout the larynxand trachea, the specific cause 
of which was uot determined. 

IS HJuk 2 <laya before its death. Heart muscle pale ; iu right 
a pale and dark gelattuous clot. Liver sprinkled with a, 



169 

grayish spots, apparently uocruaeil tissue. Spldon normal. Ridaeys Iiijeeted witb 
uraiesaud eular^'ed. Traobea and utaoiibagnsDoniial. On uover-glasB preparatiuus 
from ttae tivec are miuute bodies nbich appeared to bu liacturin. Tubes of agar 
inoculuted with a bit of the lilooil and liver developed a rich grayish growth not 
distiugaisbable from an agar culture of swiDe-plngue bacteria. 

April 'M a rabbit was iuociilated Hnbcutaoeoosly with a very small (quantity of tbe 
grovrth from iho blood cti it uro. Tbe rabbit died iu 20 hours. luuumerable swine- 
plague bacteiia in tbe variooa organs. The polar tilaiii mas vory marked in stained 
cover-giaas preparations, pure cultures of tbe same bacteria were obtained from tha I 
bloci.1. 

April S6 two fowla were inoculated with an agar culture from tbe blood of fowl 
No. 1. The Biirraee growth of the agar culture watt diluted with about 1 cubic cen- 
timetre of Bterilincd bouillon. Of this dilution, fowl n received 0.5 cubic centimetre 
Bubcatanoously over tbe pectoral muscle, and fowl b received 0.5 cubic centimetre 
into the pectoral muscle. 

Fowl b died May 4. At point of inoculation a yellowish membrououa sequestrum 
beneath the skin over an area about 2 iucbes long ; bem^ath this tbe pectoral muscle 
was uecroaed to a depth of about one-ba1f iuuli. The surrouudiug musole was 
sprinkled with punctil'orm beinorrhages. Heart niuHcle pale ; cousiderable scram in 
pericardial sac, wbicb contains also several HiiittU straw-colored coagula. Livot 
fatty ; some what mottled, witb grayish and bright red areaa. gpl eon enlarged ; friable. 
Kidneys pale ; fatty. Tbe mucous membraiio of intestines somewhat injected. 
(Esopbagns and trachea normal. Lungs of a grayish color ; not consolidated. A very 
few oval bacteria, which did not exhibit tbe polar staiu, were found in the spleen, 
liver and blood. Cultures from tbe blood and liver could not be distinguished from 
cnltnroa of swioo-plagne bacteria. 

Fowl a found dead May It. Fowl much emaciated. At the point of iiruculation a 
sequestrum about I Inch long lying beneath tbe skin ; subjacent muscle reddened. 
Heart muscle pale. Liver fatty ; quite firm. Spleeu friable. Kidneys dark. Tbe 
mucous membrane for a distance of about 4 inches below dnoiiennm in the small in- 
testine has a rou;;bened appearance, resembling superlioial necrosis. A few oval 
germs found in liver and blood. An agar culture from the liver showed same obarac- 
ters as cultures from fowl b. 

From tho agar culture of tbe blood of fowl I, agar and gelatine plato cultnres werd 
made. Tbe agar plates developed colonies not distinguishable from swine-plagne 
colonies, The gelatine plates remained free from gcowth. Other cultures have been 
made on tbe various media, but thus far no diQ'erence has been detected between the 
growth of this germ and that of swine plagne. 

Fowl No. 2. This fowl was not known to have been sick. Sternum showed evidence 
of au old injury. Liver fatly. Spleeu enlarged. Kidneys normal. Mucous mem- 
brane of duodenum generally reddened, also sprinkled with minute bright red dots, 
probably injected villi. Tbe mucous meiiibraue of thu month and lusophagus swollen, 
hypenemic, and covered witb a thin yollowish very friable exudate. The folliuloe 
and glands Aeeply reddened. Tbe laryns and trachea contained a yellowish, croap- 
ons exudate in tbe form of a tube, easily removable in sections from one-fouith to 1 
inch in length. The mucous nTenilirauo beneath the exudate swollen ; cyanased. It 
does not extend into the bronchi. Lungs normal. No bactiria were found in the liver, 
spleen and blood. Cultures madefrom these organs remained clear. Agar plate cul- 
tures were made from tbe tracheal exudate. There developed a fewehromogenicool- 
onies, and about live colonies of a very slender motile bacillos. 

Two rabbits inocalated subcntaueously with pieces of tba exudate remained well. 

A rabbit inoculated in ear vein with 0.5 oubio centimetre of a bouillon culture of the 
hacillns obtained from tbe agar plates, and two mice inoculated Bubcutaueonnly with 
the same culture, remained well. 



DESCRIPTION OF PLATES. 



Lungs oC a healthy pig iuflatert, viewed from the left side ; a. principal lobe ; S, 
ventral lobe ; v, cepbalio lobe ; e, apax of heart. The dotted area bounded 
bj the line xi/ indicates the portion usually inTolved in diiieaBe. 
s II: 

he same Iuhks viewed from beneath {Tentral, Uiaphragraatio surface) ; a, prin- 
cipal lobe; b, ventral lobe ; o, median or azygos lobe belougiug to the right 
Inag; e, apex of heart. The dotted area ehows the average exteut of the 
disease. 
P FtjiTB III : 

Lateral view of right lung of pig No. 407, outbreak IT. (See p. 24), The hep- 
atized regions are almost completely covered with a false membrane. 
I Plate IV: 

le same lung as seen from the ventral surface. A portion of the diaphragm is 
fastened to it by means of exudate. The localization of the disease in the 
anterior (cephalic) and ventral portions is well brought out in these two 

I Plate V : 

Bight Inng from ease 9, outbreak VII (see p. 38], showing hepatization of portion 
of eepbalic, ventral, and adjacent principal lobe. Minute necrotic masses 
disseminated through the hepatized tisane. On the left more recent disease 
with marked interlobular (Bdema. 
I Plate VI : 

Left Inng of Ifo. 275 (p. 46), sbowiug extensive pneumonia aft«r the injection of 
culture liquid into the right tung. There is in addition exudative plenritis 
aud pericarditis. 

(^PUTE VII : 

Section of lung passing tbrouKh bronchus. In the principal lobe around bron- 



chus the lung 
From outbreak IV. 
tpLAIB vni: 

Fig. 1. Section through 
illiiBlrative of 
The irregular p ate he 
out sorfacea of oaseo 

Fig. 3, A portion of the 
show Lug the peculiai 
ontbreali. 
1614 11 



s completely transformed Into firm c 



of tbe lobes of a diseased lung from outbreak IV, 
frequently encountered in this outbreak, 
of a bomogeoeous. faintly yellowish tiut represent the 



J 



162 

Plate IX: 

Fig. I. Collapse of groaps of lobales in the principal lobe of a pig's lang. Fre- 
quently associated with bronchitis and lang worms. 

Fig. 2. Broncho-pnenmonia. The cut surface of the lung tissue shows the 
occluded small air tubes as yellowish spots. The air vesicles or alveoli 
appear as minute yellowish dots in groups on the surface of the lungs, the 
color being due to the cell masses filling them up. The exudate plugging 
the air tubes is sometimes firm enough to be teased out in the form of branch- 
ing cylinders. This form of lung disease is frequently associated with both 
hog cholera and swine plague, and may occur independently of them. 
Plate X: 

Heart exposed by removing pericardium. The surface of the heart (epicardinm) 
is covered with exudation. The pericardium very much thickened by exud- 
ation of similar character. From case 12, outbreak VII. 
Plate XI: 

Fig. 1. Cover-glass preparation from spleen of rabbit inoculated with a particle 
of long tissue from case 15, outbreak IX. Rabbit dead within 40 hours. 
Preparation stained in alkaline methylene blue and mounted in Xylol bal- 
sam. X 1,000. 

Fig. 2. Section from left lung of inoculated pig No. 275, outbreak VII (see p. 46), 
showing extensive cell infiltration of the alveoli and small air tubes. Tissae 
hardened in alcohol, stained in alkaline methylene blue. Mounted in bal- 
sam. X 140. 

Fig. 3. A portion of the contents of an alveolus from the preceding figure highly 
magnified to show swine-plague bacteria. ^ X 1,100. 

Fig. 4. From the liver of No. 454 inoculated snbcutaneously with bacteria from 
outbreak IX (see p. 74). Intralobular capillary containing a mass of swine- 
plague bacteria. Section prepared and stained as indicated in the description 
of the preceding plate. X 1,100. 
Plate XII: 

Fig. 1. a. Surface colonies and deep colonies of swine-plague bacteria (outbreak 
IX) on an agar plate one week old. The small, round, and lenticular bodiBs 
represent the deep colonies, the larger ones the surface colonies; natural 
size, hj A surface colony enlarged 17 diameters, showing retionlated center, 
and delicate radially striated periphery. 

Fig. 2. Two deep colonies from the same plate enlarged 17 diameters. 

Fig. 3. Colonies of swine-plague bacteria from outbreak I (1886), on a gelatine 
plate, 7 days old. X 60. 

Fig. 4. Agar tube culture of swiue-plague bacteria (from outbreak VIII), about 
2 days old. Natural size. 






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Abdomen of swine, injection of swine-plague baoteria into 

Aiiar-agar, growth of awine-plague bactiTia on 83 

Age as predisposing to infactJon 133 

Air passages of domestioated .'iniiaals, attenuated swinu-plagne bacteria in.. 109 

American investigations of swine plague, review of IIB 

Animal paraaitea in swine plague 31,47,104,134 

Aacana 134 

Attenuated awine-plagne bacteria 94 

in spoiadio cases of pneumonia nod in 
Bepticdiseasesof Bwiue, and in the upper 
air passages of liealtbf swine, and otbei 

domesticated animals 109 

Baoilli elosely leBembling bog-cbolera bnollli found in swine-p1agne out- 
breaks 77 

Baeillut eoU eommania 19, 7S 

Bacteria ftaaooiated witlj awlne plague 15,77,80 

of swine plagne. {See Swine Plague.) 

Eaeteriologieal observations in swine plague 11. 32-34 

Earbotte bafalino 143 

Billings, F. S., review of report on swine plague 118 

Biological cliarttctere of swine- plague bacteria 85 

Bleisoband Fiadeler, investigations of German swine plague by 129 

Boiling water as a disinfect anl 14fi 

Bollinget, investigations of Wildaeuche 141 

Bouillon oultures, advantages of 14 

growth of Bwioe-plague bacteria in... , 88 

Breed as predisposing to infection 133 

Buffalo disease in Italy resembling swine plague 143 

Bnrrill, T. J., mUtures of swine -pi ague bacteria sent by 124 

Carbolii! acid as a disinfectant 145 

Caseation of tbeltings in swine plagoe 101 

Cats, bacteria lu air passages of, resembling swine plague . 11^2 

Cattle and game affected wilb disease re sembliug snlue plague 141 

bacteria in air passages of, resembling swine plague ...... 151 

Colonies of swine-plague bacteria . 87,88 

Comparison of bacteria obtained from airpasf>agesof domestiicatBd animals. 156 

Conolusious 149 

Conditions wbicb favor and oppose swine pluf-ne 133 

Corrosive sublimate as a disiu fee taut 140 

Cultivation of swine-plague bacteria S7 

Cultures, bow made 12 

Digestive tract in swine plagne 102 

Diphiboria and swine plague compared 117 

Diatribiition of swine-plague bacteria 135 



J 



164 



DistrictofColDinbia, investigations in 23,31 

Disinfectants, application of 146 

for 8wine>plagae bacteria 91 

Disinfection, rules for 145 

Dogs, bacteria in air passages of, resembling those of swine plague 153 

Drying destructive of swine-plague bacteria 90 

Eohinorhynchus 134 

Feeding as predisposing to swine plague 134 

Fermentation tube, use of in the diagnosis of hog-cholera bacilli 81 

Food in its relation to swine plague 137 

Fowl cholera 144 

disease caused by bacteria resemblins^ thoae of swine plague 158 

Fowls inoculated with swine-plague bacteria 21,77,96 

Galtier, investigation of swine disease in France by 143 

Gelatine, growth of swine-plague bacteria on 87 

German investigations of swine plague 125 

German swine plague 31,85,122,125 

inoculation of rabbits and pigs with 128 

Guinea-pigs, inoculated with swine-plague bacteria 21, 47, 76, 95 

pneumonia and pleuntis in, caused by bacteria resembling those 

of swine plague 158 

Hog-cholera bacilli 34,35,39.40,41,77 

attenuated varieties of 77,138 

Hog cholera, its relation to swine plague 138 

post-mortem notes in 56 

Hog cholera and swine plague (^See Swine Plague and Hog Cholera.) 

bacteria inoculated together ]06 

on same farm bub not intermingled 47 

and typhoid fever compared 108 

Illinois, investigations in 20 

immunity produced in rabbits with sterilized cultures 148 

Indol and phenol in swine-plague cultures 89 

Inoculation of smaller animals 13 

small animals with swine-plague bacteria 93 

swine with cultures of swine-plague bacteria 21, 29, 45, 71, 97 

German swine plague 128 

Intestinal lesions in swine plague 98,102,103 

Intestines of swine 17 

Intra-abdominal injection of swine-plague bacteria 29, 45 

Intra-thoracic inoculation of swine-plague bacteria 21, 45, 71, 74, 113, 121 

Intra- venous inoculation of swine-plague bacteria 71, 75, 128 

Introductory 9 

Iowa, investigations in 1 23,28 

Je£&ie8, J. A., investigations of swine plague by , 123 

Joint disease produced by intra- venous injection of swine-plague bacteria. . . 75 

Eitt, investigations of cattle disease resembling swine plague by 142 

Lime as a disinfectant 91,145 

Loffler, investigations of swine plague by • 125 

Lung disease in swine plague 98 

Lungs of swine, description of 17 

injection of swine-plague bacteria into 21, 29, 45, 71, 113 

Lung worms associated with swine plague .^ 104,134 

in outbreaks YII and YIII 31,47 

Malignant oedema bacilli found in swine-plague outbreak ••• .... .••. 80 

MkiyJand, JBveatigationB in 27 



MercurJD cliloride as a (H^lnfectaDt . 

Mice inoculated witli swine-plague bacteria ai,47,T7 

Milk, growth of Bwiue-plague bacteria in W 

Moore, Dr. V. A., report on tlie presence of aeptio bacteria probably identi- 
cal witli those of swine plague, !u tlie upper air passages of domesticated 

anttuaU other than swine 151 

Morphological obaracters of ewine-plaguebaoterin 85 

Necroais of the longs in swine plagne 101 

Kew Jersey, InTeatigationa in . . S7 

Parasites in their relation to swino plague l:)4 

Pathogenic aotion.of swine-plague baot«ria . H'i 

Peritonitis in swine 112 

Peters, F., investigatione of German awine plague 131 

Phenol and indol in swine.plague cnltnres BB 

Pigeons inoculated with awine-plague bacteria 21,77,911 

Plate oulturea, limitations of 14 

Plat«s, description of 161 

Pneamonia in cattle raaembling awine plagne .... . 144 

guinea-pigs following inoculation with swine-plagae bacteria. 47 

man and swine plagne oompared 117 

rabbits following inoculation with awine-pl.igue bacteria 94, 124. 

swine plague 98 

sporadic oases of 1U9,111,1G1 

Poat-mortem notes in Bwiue plagne 24, 32, 49, S8, 69, 72, 73, 74, 75, 76 

Practical observations on the prevention of swine plague . .. 133 

Preventive inoculation for awine plague . . 148 

Rabbits inoculated with hog-oholera ba.cilli . .. 36,40,56,79 

swine-plagne bacteria- ..16, 19, 21, 35, 32, 38, 39, 49, 64. 55. 56, 
60, 65, 83, 93. 111-116. 124, 127, 128 

Babbit aepticiemi a 125,144 

Saliva of domesticated animals containing disease germa 109,151 

Sdnceinea0uche. (See German swine plagne.) 

Schttz, investigations of swine plague by 126 

Soil, deatrnction of swine-plagne bacteria in 91 

Staining of swine-plague b 



gtrojiffylua paradoxus (long 
SnbcutaneouB inocnlatiou of s< 
Snlphnrlc acid as a disinfectai 
Swine, injection into lunga of. 



le) 

□e-plagiie bacteria.. 



134 



..21,45,71.74,113,1! 



146 



le-plague bacteria 21,29, 46, 71, 113 

veina of, with swtne-pl ague bacteria 71,75, 128 

Swine inoculated with hog-oholera bacilli 80, 97 

swine-plague bacteria 21,29,45,71,97,106,113 

large intestine of IT 






17 

snbcutaneouB inoculation with swine-plagne baotecia 21,45,71, 74,113, 128 

Swine plagne and hog cholera compared - 105 

^■" intermingled, bow distinguished 14 

^^^1 and pueumonta in man compared 108 

^^^^ aa related to diseases of other domesticated animals 14t 

^^H associated with hog cholera 14,20,23, 27, 31, 77, 63, 84,103, 104 

^^^B bacteria, attenuated varieties of 15,55,94,138 

^^^^1 carried by yonng and old animals 110, 114 

^^^B cnltivationof 87 

^^^^P distribution and tranamission of . 135 



1«6 

Pa|?e. 

Swine plagae bacteria, general characters of ^5 

injection into abtloiiien of pigs 29,45 

Inngaof pigs 21,29,45,71,113 

veins of pigs 71,75,128 

nnder skin of pigs 21, 45,71, 74, 113, 128 

inoculated into small animals 93 

non-motile 86 

objects which may carry 145 

pathogenic action of 96 

prodncing phenol and indol in caltnres 89 

readily destroyed by yarious agents 90 

caused by direct infection • 69 

conditions which may favor and oppose 133 

in Germany 125 

investigations by Billings, F. S 118 

Bleisch and Fiedeler 129 

Burrill, T. J 124 

Jeffries 123 

Loffler 125 

Peters 131 

Schiitz 126 

Welch and Clement 122 

in District of Columbia 2:{,31 

Germany 125 

Illinois 20,124 

Iowa 23,28 

Maryland 27,122 

Massachusetts 123 

Missouri 82 

New Jersey 57 

its relation to hog cholera ../ 106,138 

modified by vacciuatiou 94 

outbreaks of 19,20,23,27,28,31,47,57,82,84 

prevention of , 133,145 

preveutive iuoculation for 148 

treatment of 146 

with reference to human disease 108 

Table showing ditfereuce between hog-cholera and swinc-plague bacteria . .. 92, 105 

distribution of hog cholera and swine plague 140 

Temperature at which swine-plague bacteria multiply 89 

Treatment of swine plague 146 

Varieties of hog-cholera bacilli l^ 

swine-plague bacteria 93,136 

Virulence of bacteria, importance of 117 

swine-plague bacteria 135, 144 

Water, destruction of swine-plague bacteria in 92 

Welch, W. H., and Clement, A. W., report on swine plague 122 

Whitewash as a disinfectant 146 

Wildseuche 141 



LANE MEDICAL LIBRARY 



To avoid fine, this book should be returned 
on or before the date last stamped below. 



■1 ■.. . 




Y377 Smith, Theotald, 
see Special report ... t 
1891 avilne plague. 9002