47 
to perfection in plate cultures. In germination (fig. 4) the spores send 
out one or two, rarely three, germ tubes, which are continuous at first and 
filled with granular protoplasm. Sometimes, probably under unfavorable 
conditions, a secondary spore may form on the end of the germ tube after 
it lias grown for a short distance, and by the time this spore is formed the 
first spore is empty. The mycelium produced in this way frequently an¬ 
astomoses, and even the spores occasionally do the same thing, only one 
of the anastomosing spores sending out a germ tube. In the plant the 
mycelium is colorless, sparsely septate, and full of vacuoles. It pene¬ 
trates the cavities of the cells, running through the vessels of the wood 
as well as the more delicate tissues. The tissues infested by it soon col¬ 
lapse, the cells die, and if the fibrovascular bundles are involved, as they 
usually are, the ascent of sap is stopped. A few cells on the edge of the 
spot may usually be observed which are penetrated by the mycelium, but 
are not collapsed. 
The germ tubes developing from the spores sown in culture media may 
soon become closely septate, or may develop into a mycelium in which 
septa are only rarely visible, becoming, however, more closely septate as 
it grows older. The diameter is variable, the larger and older branches 
being as much as three or four times as broad as the smallest. The older 
branches are often constricted at the septa and sometimes instead of a 
constriction at a septum one of the adjacent segments swells up, form¬ 
ing a pear-shaped expansion at the end. The mycelium is colorless at „ 
first but in culture media soon grows dark colored and the contents be¬ 
come filled with large oily looking drops. After two or three days it is 
conspicuous in culture media by its dark color. Where it radiates from 
a single point the dark color usually extends nearly to the circum¬ 
ference oi the spot which is bounded by a light margin composed of the 
still colorless hyph®. In about seven days from the time that the spores 
are sown there are fully developed spore-producing pustules containing 
set® on the artificially produced mycelium. Fig. 5 shows one of these 
very young pustules. The character of spores, basidia, and set® is es¬ 
sentially the same as on the plant; the basidia may grow a little longer 
and the seta? are distinctly longer than any seen on the hollyhock itself 
(cf. figs. 1 and 3). The pustules may develop to a very large size, becom¬ 
ing half as large as a pin-liead. They are perfectly black to the naked 
eye except where the spores form a flesh-colored mass on the top. 
These cultures were undertaken with the hope of ascertaining whether 
the set® actually beloug to the spore forming fungus. In case of the 
Colletotrichium on the bean this has been questioned because the set® 
are frequently present in such small numbers that they are overlooked. 
This fact led to the idea that they might be parasites, or rather that 
there \^ere two distinct fungi, one living upon the other. 
In cultures I was never able to make oue of these set® germinate, 
but in one culture there were what seemed to be brown set®, sending 
out long branches from their free ends. These could not be called true 
set®, however, for they were shorter and broader than the typical ones, 
