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BUREAU OF ANIMAL INDUSTRY. 511 
which produce diseases in the higher animals are fatal to mice or 
rabbits or guinea pigs, or allthree. We need only tomention anthrax, 
black quarter, tuberculosis, fowl cholera, rowget among swine, hog 
cholera, gianders, the German swine plague, and infectious pneumo- 
nia in horses. And the converse may also be assumed as true that 
any bacteria which are harmless to these experimental animals are, 
as a rule, not the cause of virulent diseases among higher animals. 
In one of the cases given in the preceding pages in which the dis- 
ease had involved the pleura, pure cultures of this bacterium were 
_ obtained from pleural effusion, while it was obtained from the lung 
tissue by inoculating rabbits with bits of the tissue as above described. 
This case, therefore, is worth a host of negative ones, for we can not 
but believe that if the disease enters a closed cavity, like that of the 
thorax, the bacterium there found exclusively is the cause of the 
process. In asubsequent case the same organism was obtained from 
the diseased pleura, but mingled with two others, a chromogenous 
bacillus found in cases of hog cholera several years ago, entirely 
harmless, and the streptococcus already mentioned. The lungs in 
this case emitted an unpleasant odor. 
The streptococcus was isolated after much difticulty and more carefnlly examined. 
It requires a higher temperature for its growth on gelatine, so that plates made 
during the winter months were as a rule unsuccessful. It grows quite well in 
nutrient gelatine at a temperature of 75° to 80° F. The colonies in the depth of 
the gelatine are spherical, whitish; the surface growth is very scanty. In liquids 
the growth is quite peculiar. The culture liquid remains entirely clear, but a num- 
ber of white flakes appear usually in the bottom of the tube, occasionally on its 
side when the tube remains in an inclined position. These flakes do not grow 
larger than 1™™ to 2™™ in diameter. Under the microscope they are seen to consist of 
masses of interlacing chains of cocci. This accounts for the permanently limpid 
condition of the culture fluid. It serves at the same time as an important aid in 
determining the purity of a culture. This description applies to beef infusion. 
When 1 per cent. peptone is added the flakes are much larger and the deposit be- 
comes quite abundant. The liquid remains clear. They do not grow on potatoes. 
When milk is inoculated its appearance remains unchanged. 
In sections of the lung tissue they are brought out very neatly by Gram’s method, 
and the chains can be readily followed by focusing as they wind through the cel- 
lular exudate in the alveoli. This property of retaining a deep-blue color after the 
application of iodine solution is retained by the cocci when under cultivation. The 
individual cocci are slightly oval, the longer diameter being about 8 micromilli- 
meters. They strikingly resemble the bacteria causing swine plague in exhibiting 
two stained extremities joined together by a median, unstained, very narrow zone, 
They are, however, very readily distinguished from swine plague bacteria. The 
latter are much smaller, do not retain the stain when treated according to Gram’s 
method, and never appear in chains. The uncolored zone may be looked upon as 
a stage in the process of division of a single coccus into two cocci. 
The pathogenic power of this organism was tested by inoculating one-twelfthes 
of a pure, liquid culture subcutaneously into two rabbits and two mice. Both mice 
were found dead on the morning of the second day. One, being partially decomposed 
owing to the heat during the night, was not examined. In the other there was at 
the point of inoculation a slight, reddish, serous infiltration containing numerous 
streptococci. There were a moderate number in the spleen and blood from the 
heart. In a gelatine tube culture made from the lattera number of colonies of 
streptococci appeared after a few days. In the beef infusion tube a small number 
of minute white masses appeared, after three days floating, in a perfectly limpid 
liquid. These were made up of interlacing chains of cocci. The two rabbits re- 
mained well. When killed after fifteen days one of them was found infested with 
cysticerci. There was a small, softened, whitish mass in the muscles of the thigh 
at the place of inoculation. The second rabbit, perfectly well up to the twenty- 
fourth day, was then inoculated on both ears with a bit of lung tissue from swine 
plague, to which it succumbed in a few days. 
Cultures of this microbe were injected beneath the skin, into the thorax, and into 
the trachea of pigs without causing any disturbance. It therefore had but slight 
pathogenic properties, and no further attention was paid to it. It may be that it 
is the streptococcus pyogenes found occasionally in abscesses. 
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