but if the student of Nature, possessed of however humble a 
microscope, will take up with a sharp knife some of the black dust 
from one of these dark lines on the Wheat straw, and examine 
some of it with but even a moderate power, a new field of 
surpassing interest will be opened out before him; and I may 
prophesy, without fear of failure, that he will soon go on to search 
for many other kinds of these attractive objects, and that his search 
will not bo in vain. Let me add that he will find Dr. Cooke’s 
little book on ‘ Microscopic Fungi ’ a most useful guide in these 
new realms of exploration. 
But to return to our subject : this “ Mildew ” is really a second 
stage of a disease which has appeared much earlier, in May or 
June, on the M heat plant; and even this earlier development of life 
is not always the fo7is ct orign malt, but, in its turn, it may have 
been produced from another fungus living on another plant of a 
dilfercnt order altogether. 
The Puccinia, or Brand, commonly called Mildew, is the second 
stage of the Kust known as 2'richobnsts linearis, or, as some call 
it, Uredo linearis, and this last is often the offspring of yEcidiimi 
herberidis—a very pretty fungus, forming clusters of bright red 
cups containing orange-coloured spores, on the under-side of the 
leaves of several Barberries. This is no longer a matter of doubt, 
at least among the Continental Mycologists ; but I must also add 
that Dr. Cooke, who has done so much to popularize the study of 
IMycology in England, is not fully satisfied of the truth of this 
statement. The fact remains, whatever the explanation may be, 
that the orange-coloured spores of ^ddium berberidis have been 
sown on some young shoots of corn plants, while others have been 
carefully preserved from infection ; in about three weeks or a 
month the yellow spots of the Eust have made their appearance on 
the inoculated plants, while the other's have remained free from 
the disease. 
Ihe rest of the life-history of the fungus may be read every year 
in our Wheat-fields. The rust-coloured globular spores, often called 
the Uredo-spores, which are the only ones visible at first, three 
weeks later are seen to be intermixed with the dark elongated 
uniseptate spores of the Puccinia or Brand. By harvest time the 
b' rodo-spores are so scarce that they are rarely found, but if the 
weather has been suitable for the development of the fungus, the 
