SEVENTH ANNUAL YEAR BOOK— PART X. 483 



Sheep No. 108 was inoculated upon the shaven surface of the skin of 

 the foot with discharge from a diseased foot," following which a pro- 

 tective application of moist sterile cotton and a linen bandage was ap- 

 plied. A characteristic case of foot-rot developed on the fourth day as a 

 result. It seems probable that the early appearance of the disease in 

 this instance was brought about by the partial exclusion of air and by the 

 retention of more or less moisture upon the treated surface, through the 

 agency of the cotton and bandage. 



Lamb No. 94 is of special interest, having been born in an infected 

 stall in December, 1901, and having continued until March 10, 1902, in 

 daily contact with diseased sheep without showing the slightest evidence 

 of lameness. During this period of exposure the stall in which the ani- 

 mals were confined was kept dry and clean. Had mud and moisture been 

 present for the animals to walk about it, in common, the result would 

 doubtless have been different. This test was continued for seventy-nine 

 days, at the end of which time it was seen that the healthy lamb had re- 

 ceived no degree of infection, although the disease had slowly continued 

 to advance in the feet of its diseased companions until the affected mem- 

 bers had become deeply eroded. Following this preliminary test, the lamb 

 was directly inoculated, on March 10, by the application of material 

 taken from a diseased foot to both of its feet on the right side. The 

 Interdigital spaces of both feet were scraped until the surface became 

 blood tinged, when the watery exudate from the diseased foot of sheep 

 No. 62 was smeared over the scraped surfaces. There appeared on both 

 of these feet in fifteen days characteristic lesions of foot-rot, while the 

 left hind foot also developed this disease from natural infection, although 

 the lamb had previously withstood the danger incident to living in 

 daily contact with diseased sheep. It may be stated in this connection 

 that other negative results were also met with by exposing healthy to 

 diseased sheep, but although seven such experiments did not produce 

 the disease these can in no way offset the positive results obtained, con- 

 sidering that the exposure pens were always clean and dry and unlike 

 the natural conditions under which infection usually spreads. 



Indirect, by cultures. — A review of experiments made with pure cul- 

 tures of the bacillus of necrosis will serve to show the part which this 

 organism is capable of taking in the development of foot-rot in sheep. 



A pure culture of the bacillus was obtained from the liver of a rabbit, 

 which was the third in a series inoculated from the foot of an infected 

 sheep. This pure culture was then applied to the scraped surface of a 

 healthy foot of sheep No. 87. The surface upon which the culture was 

 placed began to show inflammation on the tenth day, appearing reddened 

 and moistened and exhibiting the presence of considerable heat. For 

 ten days more the irritation appeared to progress, until at the end of that 

 time a painful ulcer, coated with a grayish-white exudate, had formed. 

 Spontaneous healing commenced at this period, but its progress waa 

 slow, and microscopic examination of the watery exudation from the ul- 

 cerous opening taken nearly two months later showed that many of the 

 long filamentous forms of the necrosis bacillus were still present In It. 



