440 G. P. DARNELL-SMITH. 
The Wilt disease of Tobacco described by Erwin Smith, 
and shown by him so definitely to be due to Bact. solan- 
acearum, shows many characters similar to those found in 
the diseased tobacco crops in New South Wales, that I have 
examined. (These crops had been planted out after infec- 
tion in the seed bed with Peronospora hyoscyami). The 
questions therefore arose—does Bact. solanacearum occur 
in Australia? and is it the cause of a tobacco plant disease? 
The evidence on the first point is not satisfactory. 
Though diseases among Solanaceous plants have been 
ascribed to Bact. solanacearum, no definite evidence that 
this bacterium is really the causative organism is forth- 
coming. 
Erwin Smith“ deals very severely with the papers of 
Tryon ona potato disease in Queensland, ascribed by him 
to Bacillus vascularum solani. He concludes :— 
“Mr. Tryon is either describing mixed infections or else a 
different disease (i.e. different from the disease caused by Bacillus 
solanacearum )—why not ‘Schwarzbeinigkeit’ due to Sacillus 
phytophthorus. We shall never know the specific cause of this 
Australian potato disease until some bacteriologist takes hold of 
the problem, isolates and describes the organism in ways recognised 
as proper, and demonstrates his ability to reproduce the disease 
with one particular organism by means of pure culture inoculation.” 
I have not yet been able to complete inoculation experi- 
ments, but from diseased potatoes that were grown in New 
South Wales, and which showed all the symptoms of Brown 
Rot disease due to Bact. solanacearum (Smith), pure 
bacterial cultures, however, have been obtained; these have 
been tested upon various media. In their morphology and 
in their reactions upon the sugars, they agree with the 
characters given for Bact. solanacearum by Erwin Smith. 
They differ only in the reaction upon milk. When we con- 
sider the variable nature of milk, and of the variable way 
