32 Howard.—On a Disease of Tradescantia. 
investigated, especially when it was borne in mind that 
plants from all the greenhouses, and also from out of doors, 
were used. 
It was found in the case of the naturally-growing host- 
plants that infection started either on the upper surface of 
the leaf as a small semi-transparent dot or from the margin. 
Tangential sections of the upper epidermis containing one 
of these areas, and also of the infected margin, were made 
with a sterilized razor, and were placed in hanging-drops, 
with and without food-material. In all cases, the hyphae 
seen on the epidermis gave rise to the same species of 
Cladosporium as that mentioned above (p. 28) occurring as 
a weed in the early Botryosporium cultures (Figs. 15 and 16). 
From one of these drops pure plate-cultures were obtained, 
and the complete development was followed from a single 
spore in hanging-drop cultures under the microscope, as 
shown in Figs. 18-22. 
After spore-formation the olive-brown septate mycelium 
appeared to be exhausted, no chlamydospore-formation being 
noted, as in the case of the Botryosporium , but any joint of the 
dark olive mycelium may serve as a chlamydospore-like body, 
and reproduce the Fungus vegetatively. The spores were 
liberated by a spherical abjunctor-like body similar to that 
noted in the case of the Botryosporium . 
The Cladosporium was next grown on sterilized oak sap- 
wood, by infection with spores from a pure culture. Dark 
olive patches were produced, which gradually spread over 
the substratum. 
The spores were found to be ellipsoid in shape, simple, 
olive-coloured, 4 to 6 [j. long and 2 to 3 yu. broad. The hyphae 
varied in breadth from 4 to 6 [x. 
As seen growing on the epidermis, or after some days in 
culture, the mycelium is cut up into short segments, the 
older of which are thick-walled and dark olive-brown in 
colour. These segments may be barrel-shaped or globoid, 
and from 5 or 6 to 10 or 12 ju in diameter or more. They 
tail off into the thinner colourless hyphae with segments 
