until frost comes in the fall, or until it has used up all the avail-
able material; then it simply forms a small body about the size
of a number ten shot. The color of this body varies from a dull
white to a dark brown, and is known to botanists as a sclerotium.
It is not a seed in the proper sense of the term. As soon as the
proper conditions are present, it starts again to destroy whatever
it can make use of.
 WHAT IS BLIGHT?
 (Sclerotium.)
 In June, 1892, I discovered the cause of this disease; not,
however, until my ingenuity and almost my patience had been
exhausted. The portions that showed signs of distress had been
carefully studied under the microscope, and nothing abnormal
could be discovered. Tomato agar-culture and others tried gave
no bacteria, excepting in well advanced cases of disease, and
these cultures would not induce disease in the plant by inocu-
lation. It was quite certain that none of the species of bacteria
taken from the diseased parts and grown in the culture would
give the blight to the plant. In making culture from seedlings
a mould appeared. This was a hint in the right direction. Fol-
lowing this up, I discovered that the tomato blight is caused by
a minute fungus. After the cause had been discovered, over
eight hundred tests with the disease on tomatoes were made.
These have been carefully tabulated and show just what con-
ditions are favorable to the growth of the fungus. The work
being in a greenhouse, temperature and moisture were under
good control.
 Under ordinary conditions blight cannot be seen even with
a microscope, hut by using picro-carmine as a stain, the fine
thread-like mycelia may be seen permeating the tissue of the
host. The greater amount of growth is usually in the combian
and soft adjoining tissue.
 Another way of proving the presence of blight is to take
the portion of the suspected plant and place it in a moist
chamber. If the temperature is 80-95 F. in 48 hours you will
have a growth that will, in appearance, rival swan down. Fresh
material, such as a slice of potato or egg-plant fruit, placed within
a quarter of an inch will be siezed in a day. This bait may
be carried to a second dish. Now, if the work has been done
with the necessary precaution, you will have blight entirely free