Contagious Foot Rot in Sheep and Cattle. 103 



a second rabbit from the first, and of a third from the second is 

 usually necessary to secure a pure culture. In the seat of the 

 inoculation, in the subcutaneous tissues, there is found an area 

 of I J^ to 2 inches of soft, putty- like, necrotic tissue with a strong 

 odor of putrid flesh. Around this is a zone of inflammation 

 about % aninch thick, involving all the adjacent tissues, muscles, 

 connective tissue, etc., and beneath this a boggy swelling caused 

 by the inflammatory exudate which has gravitated downward. 



Scrapings from the necrotic mass show that it is penetrated in 

 all directions by long thread-like bacilli, Bacillus Necrophorus, 

 0.75/11 to t/u in thickness and of varied lengths up to looju. The 

 organism may even be found in the circulating blood and in the 

 lungs, liver and kidneys, where it causes small yellowish white 

 necrotic spots. It grows well in blood serum i part, 10 percent 

 gelatine i part, 1.75 per cent agar 2 parts : or again in ordinary 

 bouillon with enough agar to make it a soft jelly : or again in 

 rabbit or beef bouillon. The best growths take place beneath the 

 surface, from stab cultures, and in any case the culture tube 

 should be immersed in a flask of hydrogen, to satisfy the 

 anaerobic propensity of the microbe. The microbe is gas produc- 

 ing in artificial cultures and in the body of the rabbit kept on ice. 

 The colonies in 48 to 72 hours show as small yellowish white 

 specks, which later show a fuzzy, cotton-like envelope. The 

 organism stains well in aniline dyes, but not by Gram's method. 



Pathogenesis. Bacillus necrophorus is pathogenic to sheep, goats 

 including Angora, cattle, rabbits, and mice, and shows not only 

 in the extensive necrosis of the inoculated tissues but also, in 

 rodents especially, as necrotic spots in lungs, liver and other in- 

 ternal organs. The contagious foot-rot in cattle has been shown 

 to be due to Bacillus necrophorus (Pflugge, Bang, Von Imminger, 

 Hess, Francke, Cadiot and Almy, Mohler and Washburn, Ernst, 

 etc). Home describes a contagious foot-rot in reindeer from the 

 sores of which he recovered the Bacillus necrophorus, Francke, 

 Ernst and others have found the same bacillus in the necrotic 

 tissues of horses, deer, pigs and kangaroo. 



Accessory Causes. Though not essential these are often opera- 

 tive in making an easier 'entrance for the necrotic microbe. 

 Traumatic injuries are especially to be recognized. The ac- 

 cumulation of clay or mud in the interdigital space and the 



