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Mildew is a loose term, and includes Blight, Brand, Bunt and 
Rust, and is found even on glass. Most are white, but some 
are black, as corn rust (Puccinia graminis). 
It enters by the stomata of the leaf, and eight days after 
infection little yellow spots appear, spherical, flask-shaped 
enclosures then follow with short rod shaped conidiophores. The 
barberry was supposed to be the cause of this fungus, but this 
is not the case, as the spores hibernate. 
Dry Rot ( Merulius ). 
My attention was drawn the other day to an unoccupied 
house in Bournemouth, where, in the hall, there was the most 
beautiful fructification of this fungus, one piece, the size ol a 
soup plate and two inches thick, had around the edge numerous 
cup-shaped portions, some as large as an eggcup, and the greater 
portion was covered with minute spores like iron filings. When 
l went down to the cellar below I was able to trace the white 
mycelium right along the whole of the woodwork, and no doubt 
in time this would fructify. 
Much of the fructification we see, such as Polyporus in the 
form of a biscu’t, has a spawn right through the trunk on which 
it grows, and which will ultimately destroy the whole of the wood 
of the stem. It has been estimated that it takes seven years to 
destroy a firtree. 
Streak in the Sweet Pea. 
Ch'ttenden’s recent experiments at Wisley, on streak in the 
sweet pea help us to illustrate how fungi will invade a plant. 
Twelve young plants in pots were taken, six were inocu^ted 
with the fungus which causes “streak,” nothing happened,but the 
vitality of all 12 was lowered by over-watering, with the result 
that the six that had been inoculated became diseased, whereas 
the six which had not been inoculated recovered. This disease 
can be introduced either from the leaves or from the roots, and 
the vessels of the plants become absolutely blocked with micro¬ 
scopic fungi. 
Scab in Apples and Pears (I shew specimens of the fruit 
and tube cultures) has been thoroughly proved to be of bacterial 
origin, a mould, which is so often the case, grows along the side 
of the scab and masks the growth of the “ fusicladium,” which 
is the real organism of this disease. 
Let us now turn for a moment to the study of Galls. 
A gall is, as a rule, caused by a fly or other insect. The Oak 
Apple is the common one. A wingless fly crawls along a twig- 
till it reaches the young bud, and here selects to lay its eggs, 
trusting to the growing cells of the bud to form a little house 
for the grubs when they are hatched. The grubs in due course 
come out of the oak apple, but this time as a" winged insect, and 
ihis winged insect burrows into the ground to form a root gall. 
