484 IOWA DEPARTMENT OF AGRICULTURE. 



Another healthy sheep, No. 88, was inoculated upon the scraped sur- 

 face of its foot with the same material as that used in the preceding 

 case. The response was much more prompt (four days) in this case, 

 and the ulceration penetrated the tissues of the foot for about the same 

 depth, while the final healing, which occurred by scab formation, re- 

 quired about the same length of time for its establishment. 



A third sheep, No. 89, to which the bacillus was applied in a pure 

 state, showed inflammation of the foot in a few days and by the eighth 

 day was sore and lame as a result. The erosion penetrated beneath the 

 skin of the heels, constantly excreting foul-smelling yellowish pus. Spon- 

 taneous healing began to make its appearance in about three weeks after 

 the inoculation, and rapidly progressed to the complete restoration of the 

 foot. 



A fourth test of a similar nature gave much the same results, except 

 for a slight loosening of the hoof from a portion of one of the toes. 



From the very nature of the conditions surrounding a flock of sheep it 

 must be known that a natural infection by bacillus necrophorus in a pure 

 state is an utter impossibility. There must of necessity be material con- 

 tamination by various cocci and other bacteria from the floor of the sheep 

 pens, or from muddy yards and runs. Many of these invading forms in 

 all probability offer great assistance to the necrosis bacillus in penetrating 

 normal tissue and in perpetuating and extending the disease. 



The character and appearance of the material discharged from a foot 

 inoculated artificially with a pure culture of the bacillus of necrosis Indi- 

 cate that there is a slight difference between the disease when produced in 

 this manner and the natural type. The same redness of the surface is 

 noted and the same tendency to send deepening process of ulceration and 

 degeneration into the depths of the foot may be observed in both, but 

 the discharge will be seen to consist largely of soft yellowish pus in those 

 cases in which the foot has been inoculated with pure culture and the 

 foot afterwards kept dry and clean, while in the natural infection under 

 ordinary barnyard conditions and in cases produced artificially by the ap- 

 plication of mixed bouillon cultures the exudate has more of a yellowish- 

 gray watery appearance mixed with pus. 



There is no noticeable difference in the odor of the affected feet whether 

 the lesions are produced naturally or artificially, and the same disagree- 

 able stench pervades all cultures made from them, especially after these 

 cultures have grown for forty-eight horus or longer in the incubator; 

 Snd it is a remarkable fact that the same odor may be detected lingering 

 about the carcass of a rabbit which has succumbed to an inoculation with 

 necrosis bacilli in all cases, whether the bacteria were derived from 

 cases of foot-rot in sheep or from some other source. 



- The following experiments were made with tissue containing an 

 abundance of necrosis bacili and with mixed bouillon cultures made from 

 the pus of affected feet. 



' Sheep No. 83 was inoculated under the skin of the heel with material 

 taken form the center of a necrotic lesion in a raTjbit that died as a re- 

 sult of the ihfection of the necrosis bacilli. Here the attack was prompt 

 and serious. The animal was unable to use its foot by the third day, 

 and this degree of lameness lasted fully a week. The organism pene- 



