BUREAU OF ANIMAL INDUSTRY. 509 
acters of the microbe of swine plague as obtained from the various 
outbreaks. There is, however, a very marked difference observable 
in their pathogenic. effects. The organisms obtained from Sodorus 
and Geneseo, Ill., in the summer of 1886, both acted alike, while those 
from lowa and from the District of Columbia, studied in the winter 
of 1887, also acted alike, but different from the two former. In the 
preceding report a number of cases are cited in which subcutaneous 
injections of cultures from the two first sources produced in pigs a 
very marked sclerosis of the liver, with pronounced icterus. Neither 
the organisms injected nor any other were found in the organs after 
death. Fowls were also killed by large doses and presented exten- 
sively local lesions. The organisms from the two latter sources had 
no effect upon pigs when injected hypodermically, even when very 
large doses were given. Fowls were likewise undisturbed after in- 
oculation. On rabbits the difference was also noticeable. Inocula- 
tions of bacteria from the first class usually produced an extensive 
plastic peritonitis, lasting nearly a week before the animal succumbed. 
Inoculations of bacteria from the second class produced invariably 
a septicemia, fatal within twenty-four to seventy-two hours. Per- 
itonitis was either absent or barely manifested. Whether this dif- 
ference is due to an inherent difference in the bacteria or to surround- 
ing circumstances, such as temperature, attenuation due to cultiva- 
tion, etc., can not be determined at present. 
REMARKS ON THE CAUSATION OF SWINE PLAGUE. 
The difficulties attending investigations of diseases which have 
their seat in the lungs, and which are presumed to be caused by spe- 
cific bacteria, are due to the accidental presence of various other 
parasites. The air, as it is drawn into the lungs, carries with it the 
organisms suspended in it. From the mouth, which contains many 
bacteria, some may be carried accidentally into the air-tubes with 
the saliva or food. 
When disease germs have obtained a foothold and produced a de- 
struction of tissue or an infiltration by which the vitality of the tissue 
cells has been greatly reduced, other bacteria may also gain a foot- 
hold and multiply, although this may have beenimpossible in a nor- 
mal lung. 
In examining sections of diseased lung tissue different forms were 
found, no two lungs showing the same micro-organisms. Among 
those which were found several times was astreptococcus, appearing 
in the alveoli in the form of long chains. These chains were im- 
bedded in the mass of cells which filled the alveoli. In some sec- 
tions groups of cocci, in others masses or bacilii were observed. 
Finally in the early stages bacteria were very scarce, and if the dis- 
ease ran a very rapid course only the bacteria, which we regard as 
the cause of this disease, were present inlarge numbers. When por- 
tions of the lung tissue died and then appeared as homogeneous 
masses imbedded in diseased but still living tissue, bacteria of every 
description could be observed in thesedead masses and the lung itself 
usually emitted a putrefactive odor. 
In the interpretation of these sections under the microscope we 
must be very careful in assigning any particular réle to the bacteria 
present. Most of them are there because of the previously existing 
disease, which, soto speak, prepared the soilforthem. In the second 
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