of its tissues, which allows the penetration of the germ ? Do not all 
incipient tissues of the growing tip of full-grown plants likewise ex¬ 
hibit this immature condition ? 
With our ordinary cereals further experiments did not, indeed, ap¬ 
pear to be practicable on account of their small size. The growing tips 
of oats, barley, wheat, etc., are too small; it is here scarcely possible to 
bring the fungous germ into the still closed parts of the bud ; the young 
ovaries are also too minute to work on with sufficient clearness of view. 
But I will nevertheless add that the penetration of fungous germs 
which I had here introduced into the heart of the growing point by 
means of the long drawn out point of a spraying flask, was established 
by direct observation and the threads of the penetrated germs could be 
seen in the leaves. 
But the long series of experiments which I conducted with the larger 
cereals, corn and sorghum (Hirse ),proved this much more convincingly. 
Here the tip is more open. The unexpanded leaves of the bud, folded 
one within another, open in the form of a large cornet into which we 
can spray with the syringe flask unlimited quantities of the nutrient so¬ 
lutions containing sprout conidia. These soak down deep between the 
closed leaves, and in corn, can even reach the growing tip itself with its 
young staminate panicle, in case the latter, in a somewhat advanced 
stage of development, has already pushed upward far enough in the 
bud. Furthermore, in corn the large adventive incipient roots on the 
lower part of the axis, and the pistillate spikes, particularly, which ap¬ 
pear later upon the fully developed axis as sprouts in the leaf axils, 
offer excellent places of attack. Of course these experiments had to 
be made on large plants, or, in case of the infection of pistillate spikes, 
on nearly full grown ones, in the open air, where any other protection 
than a temporary covering with large straw mats was no longer 
possible. 
In order, first, to consider the experiments with sorghum and Usti - 
lago cruenta , its associated smut, I will add that I have infected in the 
heart more than GOO plants from 1 to 3 feet high, by simple injection of 
the fluid containing the sprout conidia. After four days the further 
developed portions of the growing point, in so far as they had come into 
direct contact with tbe infective fluid, appeared somewhat yellow. Upon 
superficial sections, the picture of the penetration of the fungous germs 
was a very clear one. The whole surface was covered with holes, from 
which big and luxuriant tubes extended into the inner parts of the 
young leaves, while through their influence was brought about ob¬ 
viously a faint yellowing, and later a more or less distinct wrinkling 
and shriveling of the attacked leaves. In thin cross-sections were to 
be found dozens of penetration spots cut through accidentally, while the 
fungous tubes grew through the entire tissue of the young leaves. That 
in this case only the young leaves were accessible to the fungous germs 
was shown on the older portions of the other leaves, which, though 
