126 
W. T. THISELTON DYER. 
remedial measures which he has based upon his view of the 
matter are inadequate. 
Dr. Thwaites, in a letter to the Ceylon Government, written 
September 2Tth, 1879, points to the fact, which is undoubtedly 
striking, that the disease, after its first appearance at Madul- 
sima in 1869, showed itself at widely separated points and 
over considerable areas in the two following years. He thinks 
this must, no doubt, have been due to the presence of 
inconceivably minute germs floating in the atmosphere and 
carried by the wind/’ These minute germs are, however, 
as far as I have been at present able to understand, com- 
pletely hypothetical, and, as will be seen, it is possible to 
explain the transference of the disease to remote points from 
its original centre of dispersion in accordance with known 
means. Before the investigations of Mr. Abbay had first 
brought to light the important fact of the extensive develop- 
ment of the Hemileia in the mycelial stage, Dr. Thwaites, 
at a loss to divine how the coffee plants could be infected 
when the spores had all been shed, hazarded the remark. 
In what way the coffee tree receives the infection remains 
to be ascertained, and from the subtlety of the operation this 
will have to be inferred, rather than discovered, by direct 
observation of the process. It would seem most probable 
that the infecting matter contained in the spore is absorbed 
by the tender rootlets of the coffee tree, although it is 
possible to conceive it might also be introduced into the 
tree through the very young foliage.” This was in 1874; 
in the following year Mr. Abbay, having demonstrated the 
universal prevalence of the mycelium. Dr. Thwaites felt 
himself constrained ” to give up the idea of an “ absorp- 
tion of the fungus matter by the roots.” He is, however, 
still unable to account for the fact that after a coffee plant 
has had all its leaves removed and has been treated with 
sulphur and lime, its young foliage speedily exhibits once 
more the evidence of the disease. Mr. Morris attributes 
this to direct infection by wind from neighbouring planta- 
tions or wild coffee trees on which the Hemileia is in a state 
of ripe fructification, and he points out reasonably enough 
that, till all plantations unite in preventive methods, and 
wfild and neglected coffee is destroyed and rooted out, no 
method of remedial procedure has a fair trial. Dr. Thwaites, 
however, in 1874, expressed the opinion that the fungus 
was present in the growing tissues generally of the coffee 
pl^nt in diffused form,” and in his latest communication on 
the subject, dated January 8th of the present year, he states 
that the phenomena of the earliest appearance of the leaf 
