MEMOIES. 
The Coffee-leaf Disease of Ceylon. By W. T. Thiselton 
Dyer, M.A., F.L.S., Assistant Director, Royal Gardens, 
Kew. With Plates IX, X, XI, XII, XIII, and XIV. 
During the last ten years a parasitic fungus has devas- 
tated the coffee plantations of Ceylon and Southern India, 
and is now slowly spreading eastward through the coffee- 
growing countries of the old world. Its history commands 
our attention as the enemy of one of the most important 
industries of the tropical possessions of the empire. In 
itself, moreover, it is an interesting biological study, supply- 
ing, as it does, a striking analogy in its first appearance, 
progress, and effects, to the epidemic diseases of animals, in 
regard to which, however, so far, there is only a presump- 
tive probability in favour of the view that the physio- 
logical disturbances or organic lesions which are charac- 
teristic of them are due to the introduction into their 
tissues and subsequent multiplication thereof some extraneous 
organism. 
The early history of the disease is well ascertained in 
Ceylon. Before 1869 it was altogether unknown, and the 
fungus which causes it had not been detected, notwithstand- 
ing that the plants of this group had been diligently collected, 
no less than 1190 species (of which two thirds are endemic) 
having been described.* In May of that year, in a com- 
paratively new estate in the Madulsima district, which 
occupies the south-western portion of the hilly country,' a 
few plants were noticed which had light-coloured patches 
on the under side of their leaves ; and these patches, on 
closer examination, were noticed to be dotted over with 
orange-coloured dust. In July following two or three acres 
were found to be affected in this way. From this time it 
rapidly spread, till in 1873 there was probably no estate in 
the island entirely free from it. 
* Berkeley and Broome, ‘ Journ. Linn. Soc. Bot ,’ vol. xiv. 
VOL. XX. NEW SER. I 
