598 PROCEEDINGS OF SECTION G2. 



We are, therefore, forced to consider other means of infection 

 conveyance operating naturally, and the only available hypothesis 

 seems to be that the bacterium is naturally introduced into the 

 derma and subcutaneous tissues or the submucosa of the mouth, 

 by vegetable prickles, thorns, etc., or it may be through the teeth 

 alveoli while the temporary teeth are being shed. At first sight 

 thedefinite seasonal incidence seems to militate strongly against 

 such a theory ; but on the other hand it must not be forgotten 

 that all the phases of braxy we have dealt with in different 

 countries occur when the ground is bare — the European during 

 frost without snow, the Tasmanian at the end of winter, the Vic- 

 torian in the dry summer when herbage is at its minimum growth, 

 and the New Zealand when the lambs are forced to lie on the 

 puddled ground. In New Zealand the great reduction of the cases 

 which followed the provision of the dry camping ground of a grass 

 paddock attached to the turnip paddock is especially noteworthy. 



The absence in the naturally-acquired disease of the extensive 

 subcutaneous oedema noted in experimental cases is the chief 

 objection to this theory ; and against it may be placed the fact 

 that subcutaneous oedemas are always more or less present in 

 naturally-affected cases, though they may not be extensive. The 

 muscle lesions may be almost entirely avoided by the experimenter 

 being careful not to introduce the syringe needle into the muscu- 

 lature. The age incidence is probably explained by natural 

 immunization through the ahmentary canal. 



To anticipate a possible criticism to the effect that the bacilli 

 in question may not be the actual causes causans, and that the 

 real agent may be a filterable virus, it may be stated that the 

 latter has been eliminated. Experiments conducted with filtered 

 serosity, with blood containing no bacilli, and with serosity remain- 

 ing apparently sterile after incubation have proved always negative. 



That the organism isolated and described is the actual cause 

 of braxy diseases investigated cannot be doubted, on careful 

 comparison of the general lesions in the natural and experimental 

 cases as detailed, bearing in mind the pathology of the lesions 

 as well as their situations. 



Prophylaxis. 



Both Neilsen and Jensen found that with dried tissue contain- 

 ing the bacteria they could confer immunity to bradsot, but the latter 

 considered the method dangerous, although the former reported 

 general good results in his district in Norway. 



Hamilton recommended the drenching with cultures of sheep 

 in the " immune " season, and professed to have demonstrated 

 the efficacy of this method, which is also considered by Dr. Willmot 

 likely to be of value in Tasmania. I am informed on good authority 

 that later on further experiments demonstrated that sheep treated 

 by this method did not display greater resistance to the natural 

 disease than did sheep on the same farms not so treated, and the 



