482 IOWA DEPARTMENT OF AGRICULTURE. 



the lameness of these lambs could have originated in swampy or muddy 

 pastures. 



Among the first experiments made by this bureau, preparatory to the 

 publication of this article, were some for the purpose of investigating the 

 contagious nature of the disease. By means of careful tests performed 

 with the purulent exudate from the feet lesions of these animals it was 

 proved that foot-rot could be produced at will in healthy sheep not only 

 by spreading a little purulent matter from a diseased foot upon the scraped 

 interdigital skin of sound feet, but quite as readily when bouillon cultures 

 inoculated with some of the discharge from an affected foot were applied 

 in a like manner, even when the cultures used were of the third genera- 

 tion of the original growth. 



It appeared from these experiments that the disease was dependent upon 

 a specific organism for its existence, and that this organism could be read- 

 ily perpetuated by the employment of the usual methods of bacteriological 

 culture. 



Microscopical examination of the purulent material discharged from 

 the open sore of a case of foot-rot revealed, among other bacteria, the con- 

 stant presence of long thread-like bacilli, which conform to the character- 

 istics of bacillus necrophor'us , and which are capable, when brought in 

 contact with the foot of a healthy sheep, of producing sores similar to those 

 found in natural outbreaks of foot-rot. 



Wherever it gains access to animal tissue it causes progressive degenera- 

 tion and destruction, showing a tendency to spread in every direction from 

 its first point of attack, and leaving behind as it advances a soft, dead, 

 cheesy mass as the result of its poisonous effect upon all contiguous tissues. 



EXPERI.MENT ON SHEEP. 



The readiness with which the disease will spread from sheep to sheep, 

 when the flock is kept under suitable conditions for such spreading, has 

 been recognized for many years by sheep owners. In addition to the 

 practical demonstration of its contagious character, which has been given 

 in past years in nearly every sheep-growing state in the Union, many 

 experiments have been made with the idea of determining the cause of 

 the transmission of the disease from one sheep to another. For this 

 purpose numerous direct inoculations with material from diseased feet 

 Ijave been made during this investigation, and in order to show the 

 effect of pure cultures of the necrosis bacillus indirect inoculations have 

 also been performed. A brief record of these two classes of experiments 

 upon sheep will here be given. 



Direct, hy pus from affected foot. — Two sheep, Nos. 40 and 63, were 

 inoculated on the scarified interdigital skin with some of the exuded 

 matter from an infected foot, and developed the disease in typical form 

 in seven days in each case.* 



Sheep No. 313 was inoculated with discharge from an infected foot 

 on the shaven surface of the cleft of its foot. This was followed by the 

 appearance of a characteristic inflammation on the ninth day, and the 

 inflammation gradually developed into the usual course of ulceration seen 

 in this disease. 



•In many cases where foot-rot was produced by Inoculation antiseptic treatment 

 was applied and a cure eflected as soon as the disease had become characteristic 



