UG 
OliANGE MOULD ON FOREST TREES. 
•with the yellow dust, and some with only the brown specks, and 
also the affected leaves of some large forest trees which have the 
rust or yellow dust upon them. If this jDest is to go on affecting 
Coffee trees year after year, we shall never get an average crop 
from our trees ; it is becoming a very serious matter to those 
interested in coffee.’ 
“ It need hardly be said that the Coffee-leaves with the yellow 
dust were affected by the too well-known Hemileia, and that the 
leaves were thoroughly covered with this pest. As to the same 
fungus having extended itself to the forest trees, some observa- 
tions are necessary. Before entering upon the details, it may be 
fittingly remarked that the plan adopted in this instance of send- 
ing the leaves with the information is one of considerable im- 
portance. The statement that the Coffee disease was extending to 
forest trees is just the sort of statement which would be greedily 
accepted, and no amount of description by unskilled or unpractised 
botanists would have sufficed to arouse any suspicion that the 
parasite of the forest trees was quite a different species. 
“ The fungus on forest leaves very much resembles that of the 
Coffee-leaf, it occurs also on the under surface in roundish or con- 
fluent patches, is of the same orange colour, and certainly so 
closely resembles it externally that a mycologist might be deceived 
without microscopical investigation. There are, however, in the 
orange patches two kinds of bodies found mixed together, instead 
of one as in the Hemileia, one of these colourless, with a warted sur- 
face, the other smaller, smooth, and orange. It was some time before 
the structure could be clearly determined, and what the relation of 
the coloured to the uncoloured bodies. After many failures and 
some hours’ examination, I believe that I have succeeded in 
determining the structure, and submitted my results to the Rev. 
M. J. Berkeley, who coincides in the opinion that the structure is 
correctly determined. The slender attachment of the spores in all 
moulds, especially when quite mature, render the structure diffi- 
cult to ascertain. It is only by persistent effort that the spores 
can at length be discovered in situ. The present is no exception, 
but I think that the following details represents the fungus in 
question. The under-surfaces of the leaves present the mould in 
small orbicular, sometimes confluent, bright orange patches, from 
I line to one-third of an inch in diameter. These patches are 
composed of small tufts of short thick uncoloured sporophores, 
with a globose, unicellular head, studded on the surface with 
papilla? ; the stem consists of from two to three, rarely four or 
five cells, a portion remaining attached to the globose head when 
that is detached. The entire length of this sporophore is about 
•05 -'06 mm., and the diameter of the globose capitnlnm *03 mm. 
Mixed with these sporophores are globose, smooth spores, con- 
taining a bright orange plasma, and about -0125 mm. in diameter. 
These spores appear to be generated on the papillie which surround 
