268

PATHOGENIC BACTERIA.

appearance when the central part is pale and the periphery
red. As the colony ages the red color is lost and it be-
comes dull white. The colonies are very adherent to the
surface of the medium, and are said to be of cartilaginous
consistence. The organism also grows in milk without
coagulation.

Upon potato the development is meagre, slow, and
with very little tendency to chromogenesis. The color-
production is more marked if the potato be acid in reac-

FIG. 70.—Streptothtix Madurae in a section of diseased tissue (Vincent).

tion. Some of the colonies upon agar-agar and potato
have a powdery surface, no doubt from the occurrence of
spores. It is, of course, an aerobic organism.

Under the microscope the organism is found by Vin-
cent to be a streptothrix—a true branched fungus con-
sisting of long bacillary branching threads in a tangled
mass. In many of the threads spores could be made out