10 
PRESIDENT S ADDRESS. 
take too long to explain all the reasons in detail, but there is strong 
presumptive evidence that this is brought about by insect agency. 
No country in the world suffers greater injury to its Wheat crops 
from this disease than does Australia. With us it is only in 
certain years that the disease causes us much injury, but in 
Australia immense loss is sustained every year. But the Barberry 
is not an indigenous plant in that country, so that some other 
explanation must be afforded. 
While there is no doubt that the Barberry is not indigenous in 
Australia, I find upon inquiry that it is sometimes grown in 
gardens, although not so commonly, I am told, as the Mahonia is. 
It is however, I think, clear, that the Barberry plays a much less 
important part in the dissemination of the disease in the Colonies 
than is the case in Europe. It is hardly possible to imagine, 
however, that the disease ever started in Australia, except from the 
cluster-cup stage ; nor, indeed, that it does not, from time to time, 
here and there originate even now in this way ; still there are 
reasons for the belief that this is much less necessary for its 
perpetuation than is the case with us. In the first place, the 
colonial agriculturists do not complain of mildew at all, it is 
“ The Bust in Wheat ” which does them injury. The examination 
of specimens of diseased Wheat from Australia shows this 
perceptibly. The little pustules of rust-spores cover the plant, 
but the black lines of mildew are few and far between. This fact 
shows that the fungus has been for many generations reproducing 
itself without the intervention of the cluster-cup stage, a condition 
which is exemplified by many allied species of the fungus parasite 
in Europe. But this is not all. I have received specimens, in 
the mildew stage, from various parts of Australia, for the purpose 
of experiment ; but I have hitherto been unable to induce these 
spores to germinate, although they have been placed under the 
same conditions of moisture and temperature as English spores, 
while the latter germinated with the greatest facility. The only 
difference in the treatment between the two has been this, — the 
one came directly from Australia ; the other had been exposed 
during the resting stage to those variations of temperature which 
