BACILLUS NECROPHORUS GROUP 347 



filaments. Bouillon becomes turbid, and then gradually clears, 

 with subsidence of the organism. Gelatin is not liquefied. 



Physiology. B. necrophorus is an obligate anaerobe. Its 

 temperature growth limits are between 30 and 40, with an 

 optimum at about 35. The organism is readily destroyed by 

 disinfectants. No pigment is produced. A very characteristic 

 odor, " between the odor of cheese and of glue," may be noted in 

 both cultures and lesions. No enzymes capable of liquefying 

 gelatin or blood-serum are produced. Gas is formed in bouillon. 

 Milk is not coagulated, nor are acids formed. Indol is produced. 



Pathogenesis. Experimental Evidence. Rabbits may be read- 

 ily infected with the B. necrophorus. A subcutaneous injection of 

 a small amount of necrosed tissue results in the death of the rabbit 

 in about a week. The inoculated area is necrotic to some depth, 

 and to a distance along the surface of half to one inch from the 

 point of injection. The necrosis is complete, and the tissues wholly 

 disintegrated. In some cases gas-bubbles may be observed. The 

 inoculation of pure cultures results in death more slowly; fre- 

 quently two weeks are required. The animal dies suddenly 

 after a series of convulsions. Mice are readily infected. Guinea- 

 pigs are much more refractory, but occasionally die as a result 

 of inoculation. There seems to be abundant experimental evi- 

 dence to connect the B. necrophorus with many types of necrosis 

 in animals. There is no evidence that the organism enters the 

 normal healthy unbroken skin. It is usually a secondary invader. 



Character of Disease and Lesions Produced. Mohler and 

 Washburn have given an excellent resume of the conditions under 

 which this organism has been found. In many of these conditions 

 it has not been satisfactorily established that this organism is the 

 sole cause, for pyogenic cocci and other organisms may produce 

 the same changes. More work is needed upon these infections. 

 The possible presence of this organism in necrotic infections of all 

 kinds must be borne in mind. The organism has been reported 

 from the following infections, and probably in most cases is res- 

 ponsible for the accompanying necrosis: necrotic dermatitis, 

 necrotic scratches in the horse, necrotic pox in horses, cattle, 

 goats, and hogs, several types of necrosis in rabbits, necrosis of the 

 hoof in the horse, necrosis of the mouth and esophagus, ulcerative 



