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 dark-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 DIPHTHERIA COLUMBARUM. 



Described by Loffler (1884), who obtained it from diphtheritic pseudo-mem- 

 branes in the mouths of pig-eons 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 exudate. 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 septicaBmia (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 aerobic, 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 SL 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 to a 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 Loffler 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 



