THE CAUSE OF BLACK DISEASE. 23 



the latter have been conclusively proved to be the etiological factor of each 

 condition. In the meantime, however, one may express an opinion as to 

 the probabilities, based on one's own experience and on the published work 

 of others. 



The evidence for the identity of black disease and the braxy-like disease 

 in Tasmania and Victoria is very strong, save that the organism claimed 

 by Gilruth to be the causal factor of the latter, is not the same as that 

 responsible for black disease. On referring to his account of his investiga- 

 tions* one finds the following remarks re the disease in Victoria (page 570) : 

 '" The soil is not rich . . . it is fairly watered by means of springs 

 . . . which generally result in the formation of a small swampy area 

 around each. As a consequence, nuke disease is common." Concerning 

 post-mortem appearances he notes among other changes (page 571) " The 

 stomach is always more or less deeply congested, but I have observed no 

 ulceration. The liver often presents a mottled appearance, due to circum- 

 .scribed irregular areas of necrosis." 



As regards the pathogenic organism, lie describes what he considers to be 

 the characteristic organism as being present in the effusions, organs, and 

 even in the blood itself, but never in a state of purity. He. further adds 

 (page 572) : " The necrosed liver areas also show the characteristic bacilli 

 4n great numbers" 



Regarding the disease in Tasmania, he says (page 570) : " The liver is 

 very often congested, and may show yellowish necrotic areas" 



The italics in the foregoing quotations are mine. 



It is evident that the necrotic hepatic lesions were looked upon as 

 secondary in character, for no experimental work appears to have been done 

 with them. The materials for animal inoculation being blood and exudates, 

 it follows that the bacilli he saw in sections of hepatic necrotic lesions 

 were not necessarily identical with those obtained from the blood and 

 -exudates of the same animal or animals, in view of my own experiences. 



The indications are pretty clear that black disease in New South Wales 

 and the braxy-like disease in Victoria and Tasmania are identical. Now, 

 seeing that Gilruth definitely claimed to have isolated the causal organism 

 of the latter disease, it is evident that it should be identical with that 

 isolated from black disease. I have had opportunity of examining two dif- 

 ferent lots of material containing the bacilli isolated by Gilruth, and find 

 that they are not the same, either morphologically or culturally, as those 

 isolated from cases of black disease. This being the case, one has to explain 

 the difference. Reference to my first article will show that in the early 

 period of the investigations my results agreed with those of Gilruth bac- 

 teriologically, but it was subsequently shown that the bacilli that had been 

 isolated from sheep found dead, although death had only recently taken 

 place, could not be acknowledged the indisputable cause of the disease. 



Proceedings of the Australasian Association for the Advancement of 

 Science, 1911, vol. 13. 



