THE PRINCIPLES OE BOTANY. 
203 
at the same time it will be well here to state that, like the 
Uredines, the Puccinise are found on most plants, and the 
black spots so common on the under sides of rose and bramble 
leaves, the brown spots on the mints, and the dark red ones 
on the saxifrage, are all under the microscope resolved into 
clusters of most beautiful and singularly formed plants, the 
general characteristics of which are that they consist of from 
two to four, and even six cells, placed end to end, like rows 
of attached beads, in the interior of which are the sporules. 
These are surmounted on more or less elongated pedicles. 
In the Puccinia graminis we have a series of oblong or 
linear clusters — first of a dirty-brown colour, afterwards 
black, situate on the leaves and stalks of corn crops, but 
especially on wheat, and which is commonly but erroneously 
known to the farmer as mildew. 
The spore cells are mostly two in one form, and divided 
by a slight constriction, and having a short pedicel ; in b the 
constriction is much greater, and the pedicels twice the 
length. Both these are common to wheat, and they occur 
with examples of a single-celled spore case, and, indeed, show 
all stages of progress, from the Uredo to the Puccinia, on 
which account Professor Henslow was inclined to consider 
them as but different states or stages of Puccinia, a notion in 
which, from repeated examination, we entirely coincide. 
But be that as it may, the Uredo, which mostly commences 
its attacks on the blades and sheaths of the leaves, always 
results in a lessening of the quantity and an injury in the 
quality of the grain, and this effect is greatly aggravated if 
the Puccinia succeeds, as its effects are more confined to the 
straw, and are the cause of great injury to the farmer no less 
than to the people at large, as our daily bread is not only 
diminished thereby, but, as it is deficient in nitrogen, it is 
not so nutritious. From this cause straw is so injured that 
there is reason to believe that horses or cattle partaking of it 
largely in the shape of chaff suffer immensely, but whether 
from a deficiency in its nutritive value, or from any medicinal 
effects, has not been made clear. 
Various modes of obviating this defect have been proposed, 
amongst which steaming the chaff is mostly in favour. That 
this process would render it more digestible is probable ; but 
as the real defect appears to be a conversion of feeding matter 
in the growth of fungus, we should advise choice to be made 
of bright straw for all feeding purposes in which this article 
— poor even when at its best — is employed. 
This affection of wheat is the one so prevalent in Australia, 
and also at the Cape, and, indeed, it would seem in all newly 
