Bradsot. 59 



_ Subcutaneous injections of pure cultures produce only excep- 

 tionally a generalized affection in sheep when the clinical picture re- 

 sembles blackleg (hemorrhagic-gelatinous infiltrations and gas forma- 

 tion in the subcutaneous connective tissue and muscles). In most 

 instances only a local swelling develops which later disappears. Ani- 

 mals thus affected which recover later resist natural infection. Guinea 

 pigs, rabbits and pigeons are also susceptible. The natural mode of 

 infection is at present not known with certainty, but it is possible that 

 the infection occurs through slight injuries along the upper digestive 

 tract. After the appearance of the disease a change of pasture and 

 stable as well as a thorough disinfection of the premises is indicated. 



Immunization. Nielsen used a heated powder made from kidney 

 tissue, containing numerous bacilli and spores obtained from sheep 

 which had died spontaneously. This method was principally employed 

 in Iceland, but with uncertain results. Tokishige, on the other hand, 

 proved that horses and goats treated intravenously with the virus 

 yielded a potent serum. Jensen worked up the three following methods : 



1. Bight-day old spore-containing bouillon-serum cultures of the 

 bradsot bacillus are rapidly evaporated at 50° C, finely pulverized 

 and mixed with a small quantity of gum tragacanth.' The dose 

 (0.005-0.03 gm.) must be established by test inoculations, as the suscepti- 

 bility of sheep varies in different breeds and ages. The immunity is 

 satisfactory, and no losses were observed from the vaccinations in the 

 Faroe Islands, while in Iceland they amounted to 1.5%. 



2. Blood serum of horses immunized by intravenous injections of 

 virulent cultures (0.02 gm. serum protect guinea pigs against fatal 

 infection) is dried, pulverized and mixed with the vaccine described 

 under 1. For practical purposes a mixture of 0.005 gm. each of culture 

 and immune serum is used. 



3. Threads are placed in 3-4 weeks old dextrose bouillon cultures 

 and then dried at 40-50°C. These threads are inserted with a suitable 

 needle under the skin on the inside of the thigh and left there. The 

 practical results appear uniformly satisfactory. In some cases, how- 

 ever the acquired immunity was insufficient. 



In Iceland and the Faroe's about three quarters of a million sheep were vac- 

 cinated by these three methods previous to 1906. The losses in the first group 

 which included 208,805 animals amounted to 1.45% as a result of the vaccination, 

 and 0.32% later on. In the second group of 52,327 the losses were 0.03% and 1.93% 

 respectively. In the third group of 15,934 animals 0.03 and 4.65% succumbed, while 

 in the unvaceinated sheep it reached 4.21, 5.04 and 5.80% respectively (Jensen). 



In opposition to the above conception of the etiology of the dis- 

 ease, Miessner believes it is questionable whether bradsot represents a 

 uniform disease, being rather a clinical-anatomical name for any dis- 

 ease in sheep which causes death within a few hours, and which 

 manifests on autopsy an extensive hemorrhagic infiammation of the 

 abomasum in addition to an injection of the subcutis. He also con- 

 cluded from his numerous bacteriological examinations of cases con- 

 • sidered as representative of the disease, that the etiological significance 

 of the bradsot bacillus is very questionable, principally on the ground 

 that it has not been possible to produce the anatomical picture of the 

 disease with bradsot bacilli. He also failed as a rule in demonstrating 

 the mentioned micro-organism in fresh carcasses of animals dead of 

 the disease or which were killed shortly before the fatal termination. 

 He, however, failed to ascertain the true causative agent. 



