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disease, belongs to the tribe of fungi called Muscedines, which 
contains the common blue and white moulds, that are every- 
where so common, preying on decaying substances, that they 
have been called nature’s scavengers. But there are some of the 
species which only feed on living vegetable tissue, such as the 
peach and rose mildews, Ocdiwm erysiphoides, and Oidium 
leucoconium, and it is among these the egg mildew of the vine 
is found. The species was not known to botanists before 1845, 
when it was first noticed by Mr. Tucker, gardener to a Mr. 
Salter, near Ramsgate, after whom Mr. Berkley named it O7- 
dium Tuckeri. It appears on the leaves and young shoots of the 
vines, as well as on the berries themselves, marking the former 
with white, mealy, circumscribed spots in the early stage, and, 
ina more advanced state, becomes generally diffused over both. 
When viewed through a good microscope, it is found to con- 
sist of slender, branched, articulate threads, which spread over 
the surface of the spots, and have been seen among the cellu- 
lar tissue of the leaf, under the epidermis, pushing up the fer- 
tile, erect, simple filaments, which bear the reproductive spores 
at their upper extremities, through the stomates of the leaf, in 
a‘similar manner to the potato mould. ‘The effects are rapid : 
a short time after it appears, pale marks begin to show on the 
leaves, which gradually enlarge and become dry and brown as 
if frayed, which is the case with the vines at the Viceregal 
Garden at present. 
‘¢ As the berries advance, black depressed spots appear on 
them, as if they had been injured by being struck against each 
other, or with a rod. The spots spread, and the berry gets 
soft and putrid ; but if any of the branches on the bunch have 
been attacked, all the berries on that branch turn brown and 
soft, and sometimes the branch altogether. 
«‘The appearance of the vine at the Botanic Garden is 
somewhat different—the berries have become dry, with cracks 
over the surface, which seems to be the most general state of 
the disease. 
