COFFEE-LEAF DISEASE 263 



coffee. The history of this malady is almost unique in vegetable 

 pathology. A native fungus which had eluded scientific obser- 

 vation, and must therefore have maintained an inconspicuous 

 and limited existence on some native host-plant, found a wider 

 opportunity on the Arabian coffee plant and fell upon it as a 

 devastating scourge. It was first detected in 1869 on a single 

 estate; in 1873 there was probably none in the island entirely 

 free from it. Mr (since Sir Daniel) Morris had shown that the 

 plants could be cleansed by dusting them with a mixture of 

 sulphur and lime. But the remedy proved of no avail as the 

 plants speedily became re-infected. Morris had been transferred 

 to another appointment in the West Indies and Ward's duty 

 was to take up the investigation. This he accomplished ex- 

 haustively. He showed that the fungus (Hemileia vastatrix) was 

 one of the Uredineae and that infection was produced by the 

 wind-borne uredospores. Had the planters, as in Southern 

 India, left forest belts between their plantations, the spores 

 might have been filtered out and the disease controlled. As it 

 was it spread like an unchecked conflagration. Ward also 

 discovered the teleutospores ; nothing has been added to our 

 knowledge of its life-history beyond what he obtained. The 

 result of his investigations was given in three official reports and 

 in papers contributed in 1882 to the Linnean Society and the 

 Quarterly Journal of Microscopical Science. It was no blame to 

 him that his work led to no practical result. The mischief 

 admitted of no remedy. The coffee-planting industry of Ceylon 

 was destroyed and the Oriental Bank succumbed in the general 

 ruin. Leaf disease has now extended to every coffee-growing 

 country in the Old World from Natal to Fiji. 



In a tropical country leaves supply a substratum to a little 

 flora of their own, consisting of organisms partly algal, partly 

 fungal, in their affinity. Ward, who had already developed his 

 characteristic habit of never neglecting any point incidental to 

 a research, carefully studied them, in order both to ascertain 

 how far their presence affected the health of the leaf itself and 

 to work out their life-history. The outcome was three im- 

 portant papers. One on Meliola, an obscure genus of tropical 

 epiphyllous fungi, belonging to the Pyrenomycetes, was published 



