458 BACTERIA IN DIPHTHERIA. 
time for the action of the stain, after which the cover glass is again 
washed and is then ready for examination. The diphtheria bacillus 
appears in such a preparation as faintly stained brown rods, in the 
interior of which one to three Gark-blue granules may be seen. These 
are oval in form and are found at the extremities of the bacterial 
cells. Neisser and others who have made use of this method agree 
that bacilli which do not stain in this way are not diphtheria bacilli. 
BACILLUS DIPHTHERIZ COLUMBARUM. 
Described by Léffler (1884), who obtained it from diphtheritic pseudo-mem- 
branes in the mouths of pigeons dead from an infectious form of diphtheria 
which prevails in some parts of Germany among these birds and among 
chickens. 
Reddened patches first appear upon the mucous membrane of the mouth 
and fauces, and these are covered later with a rather thick, yellowish layer 
of fibrinous exudaie. In pigeons the back part of the tongue, the fauces, 
and the corners of the mouth are especially affected; in chickens the tongue, 
the gums, the nares, the larynx, and the conjunctival mucous membrane. 
The disease is especially fatal among chickens, the young fowls and those of 
choice varieties being most susceptible. It is attended at the outset by fever, 
and usually proves fatal within two or three weeks, but may last for several 
months. 
Morphology.—Short bacilli with rounded ends, usually associated in ir- 
regular masses, and resembling the bacilli of rabbit septicemia (fowl 
cholera), but a little longer and not quite so broad. In sections from the 
liver they are seen in irregular groups in the interior of the vessels. 
Biological Characters —An aérobic, non-motile, non-liquefying bacillus. 
Grows in nutrient gelatin in the form of spherical, white colonies along 
the line of puncture, and upon the surface as a whitish layer. Under the 
microscope the colonies in gelatin plates have a yellowish-brown color and 
a slightly granular surface. Upon blood serum the growth consists of a 
semi-transparent, grayish-white layer. Upon potato a thin layer is formed 
having a grayish tint. 
Pathogenesis.—Pigeons inoculated with a pure culture in the mucous 
membrane of the mouth are affected exactly as are those which acquire the 
disease naturally. Subcutaneous inoculations in pigeons give rise to an in- 
flammation resulting in local necrotic changes. Pathogenic for rabbits and 
for mice. Subcutaneous injections in mice give rise toa fatal result in about 
five days. The bacillus is found in the blood and in the various organs, in 
the interior of the vessels, and sometimes in the interior of the leucocytes; 
they are especially numerous in the liver. The lungs are dotted with red 
spots, the spleen is greatly enlarged, and the liver has a marbled appearance 
from the presence of numerous irregular white masses scattered through the 
pale-red parenchyma of the organ. These white masses are seen, in sec- 
tions, to consist of necrotic liver tissue, In the centre of which the bacilli 
are found in great numbers, in the interior of the vessels. This appearance 
is so characteristic that Ldffler considers inoculations in mice to be the most 
reliable method of establishing the identity of the bacillus. Not pathogenic 
for chickens, guinea-pigs, rats, or dogs. 
There seems to be some doubt whether the form of diphtheria which pre- 
vails among pigeons, and which Loffler has shown to be due to the bacillus 
above described, is identical with the diphtheria of chickens. Diphtheria in 
man has been supposed by some authors to be identical with that which 
prevails among fowls, and_possibly this may be the case under certain cir- 
cumstances. But the evidence seems to be convincing that there is an 
