The Life of, the Plant. DOF 
dust also emerge from the culms beneath the flowers, as 
well as from the leaves.’ Rye and wheat are also subject to 
this disease, wild grasses less so. It is caused by the at- 
tacks of a Fungus, Ustc/ago carbo, the black masses consist- 
ing of its emerging spores which project between the palez, 
the mycelial threads obtaining their nutriment from the in- 
terior of the parenchymatous eells. 
The smut of maize and millet are of a similar character. 
In the former swellings the size of the fist or even of the 
head are formed in the diseased part, between the cells of 
which the filaments of the Fungus which produces the dis- 
ease, Ustilago maydis, are easily found. The millet-smut, 
caused by Ustelago destruens, destroys the whole of the flower 
even within the leaf-sheaths. 
Bunt is a disease which attacks all kinds of wheat, but | 
the varieties of spelt have less to fear from it than other 
sorts, and winter- less than summer-wheat. The Fungus 
which produces :this disease, Z7//etia caries, fills up with: 
its spores the whole of the ovary, and replaces it by 
an elongated, black, greasy body of a disagreeable odour. | 
The mycelium is easily found in the parenchyma of the 
flower. ' | 
Ergot is another Fungus of this kind, which attacks the 
inflorescence of grasses, and especially of cereal crops, ap- 
pearing in the place of the fruit in the form of an enor- 
mously large grain among those that are still healthy. In 
form it resembles, therefore, the grain which it attacks ; in 
rye, for example, it is obtusely triangular, and in Phragmites 
flatly compressed. It is the ‘sclerotium’ of a Fungus 
which grows from the base of the ovary, and soon detaches 
it from its point of attachment, raises it up, and then 
encloses it or presses it aside. Ergot, although it seldom 
occurs in any great quantity, is one of the most dangerous 
vegetable parasites of cereal crops, since it contains a 
powerful poison, on account of which it is valuable in medi- 
cine, but which renders the meal quite useless when ground 
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