THE PRINCIPLES OF BOTANY. 
109 
But the best way to get rid of this fungus is not to grow 
it; and to prevent this it seems that the most efficient plan 
is to treat the seed with various strong chemical solutions, 
hence, a solution of arsenic has been employed as a dressing ; 
lime, alkalies, &c., all have had their advocates ; but the most 
general dressing now used is that of solution of sulphate of 
copper. We dress our seed with this at the rate of one 
pound to the sack, dissolved in hot water and mixed well 
with the seed the night before it is required to be sown. 
This we have found very efficient in checking smut, but how 
it acts it would seem to be difficult to determine. It is 
generally supposed that the chemical destroys the sporules of 
the fungus, but from a series of experiments we carried out 
upon this subject some few years since, we are inclined to 
think that the growth of the fungus is discouraged by killing 
diseased wheat grains, which it does by penetrating the broken 
testa and getting to the germen, which will not germinate 
when treated with corrosive poisons. Where, however, the 
wheat grains are perfect, these solutions do not penetrate to 
the embryo. It hence follows that it is highly important to 
employ as good a sample for seed as can be got, and we have 
usually found that by so doing dressing for planting is scarcely 
necessary. 
The affection just described should be distinguished from 
that known as ear-cockle, purples, or cheat, which is not un- 
common to wheat. 
In this latter the affected grains are purplish black exter- 
nally, and in the interior of the thickened testa will be found, 
not a black powder, but a white, cottony -looking substance, 
which, if moistened with a little water and placed under the 
microscope, is shown to consist of myriads of worm-like 
bodies, which, from their length and their flexile movements 
are not inaptly termed wheat-eels. 
This latter is an animal affection, and, probably, is the 
cause of the appearance of eel-like bodies in decaying paste ; 
but whether or no it be injurious by being taken into the 
animal system we, as yet, do not know. Of course, like the 
smut, when it occurs, the wheat grains are destroyed ; and in 
some moist seasons the wheat-eel is so abundant as to cause 
considerable loss. 
3. The U. rubigo, or red rust, will be seen in a series of 
ovate patches, more particularly on the chaff scales of wheat. 
The patches are of a bright reddish-yellow or orange colour, 
caused by the exudation of the bright spores of the fungus 
through the ruptured epidermis. 
Wherever these fungi appear in any quantity the corn 
