346 
Essed . — The Panama Disease. I. 
forming clusters as in Sorosporium . Very frequently globular transparent 
bodies are found in the sclerotia, reminding one of the water-clear bubbles 
which Meyen discovered between the spores of Ustilago longissima. Their 
nature is difficult to explain ; in some cases, however, I found them con- 
taining crystals of calcium oxalate. Besides the ordinary chlamydospores, 
large spore-shaped bodies of a smoky or shining black colour are seen to 
arise within the sclerotia. I shall later on try to give an explanation of 
their origin and nature (see PL XXVIII, Fig. 3). 
During the final stage of the development of the disease all parts of 
the host plant are attacked by the fungus, which, enclosing the tissue-remnants 
in sclerotia, adapts itself to a saprophytic mode of life. Numerous spores— 
chlamydospores and conidia — are formed and crowded in pycnidia-like 
cavities. The pycnidia containing chlamydospores mainly form within the 
more compact inner portions of the mass, whereas those containing conidia 
arise on the subaerial parts, now and then with chlamydospores scattered 
between them. In the leaves also I found similar pycnidia between the 
subepidermal cells, containing chlamydospores, with no visible aperture for 
the escape of the spores ; the walls in both cases were formed symphyo- 
genetically. 
All through the plant multicellular chlamydospores are met with. It 
will be shown later on that they are chlamydospores by their mode of 
origin and germination. 
Pure Cultures. 
The little-discoloured parts of the rhizome, abutting on those where 
putrefaction had gone to a great length, appeared to be most suitable for 
the preparation of the inoculation fluid, since the bacterial colonies did not 
appear in such an overwhelming number as to overrun the mycelia ; more- 
over, the inoculation was carried out on large Drigalsky plates (Agar). 
Using a favourable dilution, what appeared to be two distinct kinds of 
mycelia and two kinds of bacterial colonies were obtained. The difference 
between the two kinds of mycelia was pronounced, in the colour and the 
mode of growth ; they were transferred to separate Petri dishes. 
The one kind of mycelium was hyaline and silvery shining ; the hyphae 
were thin and the septa wide apart. On the fifth day a thickening of 
special hyphae had taken place, and a greater amount of transverse walls 
had divided them into a large number of isodiametric cells. Many branches 
were given off in monopodial fashion, and more or less vertical to the main 
axes. On the seventh day tiny protuberances arose, which the next day 
had cut off single multicellular Fusarium conidia and smaller bicellular 
conidia, which were slightly sickle-shaped or straight and always grouped 
in yeast-like fashion or in heads or bundles of 8-20. The following day 
the Fusarium conidia were seen to arise in heads of 10-50 on an incon- 
