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IV. The formation of tbe pustules in tlie very young ear did not yet 
exactly correspond to the appearances which I had formerly seen on 
fertile spikes, where each ovary had swollen individually into a tumor 
as big as a nut, so I extended the experiments still further. Ears which 
already bore silks were somewhat opened at the tip, and only the ex¬ 
posed ovaries of the spike were infected by means of the sprayer, while 
the lower were not infected. If the presumption as to the narrowly 
local action of the infection were correct, then in this case also only the 
upper ovaries would become smutty. 
The ovaries behaved with military punctuality. After 16 days the 
upper ones swelled, and became almost egg sized smut tumors, as the 
suspended pictures show. All of the ovaries lower down on the same 
spike yielded sound, normal grains. 
V. There remained only the incipient adveutive roots on the lower 
nodes of the axis as susceptible objects of attack. The beginnings first 
appear when the growing points and the leaves have reached full size, 
i. e ., when the plants begin to elongate. They appear in ajMig around 
the nodes near the ground; the farther up they are the shorter they 
remain, and then, generally, they do not penetrate into the earth. 
As soon as the tips of the roots were exposed, the infections were made 
by spraying with the atomizer, and then a shelter from rain was placed 
over the roots. Once more, after 3 weeks, individual root tips showed 
swellings of the bigness of a nut on their ends, which meanwhile had 
elongated. These swellings developed into normal smut pustules, as 
shown in this sketch. 
VI. To round out the experiments, the silks which hung far out of 
the fertile inflorescences were also infected by spraying. Here the in¬ 
fection had no result, as was to be expected. The silks remained un¬ 
changed, and their spikes, which were protected from the infection, also 
remained entirely sound. The silks, indeed, are no longer young tissue. 
The fungous germs still penetrate occasionally, but do not develop, 
because the luxuriant growth of tissues necessary for the formation of 
pustules is excluded. 
VII. All infection experiments made by spraying into the heart of 
the plant when the sterile inflorescences were already visible in the 
growing points, were also without results. Penetration spots were still 
to be found, and also fungous threads in the superficial tissues. Ex¬ 
ternally on the leaves a slight shrinking was also observed on isolated 
spots, but they recovered because the fungous germs found in the already 
too old tissues no suitable place for the production of smut beds. I 
have already referred to the fact that penetration itself is impossible 
in still older parts of the maize plant which have reached nearly full 
growth. 
According to this, the final result of all the infections with corn smut 
on maize is entirely different from the previously described results with 
smut fungi living exclusively in the grains. The smut germs come to 
