i6o 
F. T. Brooks. 
ficial layers of the wood, formed a continuous black crust similar to 
the black zones in the collar of a diseased tree. In some of the 
cultures a black line was formed in the wood block a little within the 
surface. Fig. 6 shews a section of one of these black zones in a 
block of wood on which the fungus grew in pure culture. 
Fig. 6. Ustulina zonata. Section of black zone in wood of Hevea brasiliensis 
on which Ustulina zonata grew in pure culture, x 330. 
Since returning to England I have found that the fungus grows 
well on sterilised blocks of Ash wood kept at a temperature of 25°C. 
At 12° C, however, it grows scarcely at all. 
