HABIT OF HEMILEIA VASTATRIX. 513 



tend with the pest, it is not improbable that it will spread to the 

 "West Indies and Brazil, and prove a general enemy to the coffee 

 enterprises of both tropics. 



As is now well known, the disease consists of a minute fungus 

 which appears as a parasitic growth within the parenchymatous 

 tissue of the coffee-leaf. Its fruit, which appears on the under 

 side of the leaf, is composed of numerous clusters of orange- 

 coloured sporanges borne on minute tufts of threads protruded 

 through the stomata. The disease affects the coffee-tree by the 

 repeated destruction of its leaves, thus gradually weakening it 

 till it succumbs. 



The effects of the leaf-disease upon the exportation of coffee 

 from Ceylon may be very distinctly traced. In 1869-70, before 

 the disease appeared generally upon the coffee-estates, Ceylon ex- 

 ported 1,009,200 cwt. of coffee, consisting of 860,707 cwt. plan- 

 tation-coffee and 118,499 cwt. native coffee. In 1876-77, when 

 there were 52,000 more acres in bearing, the total exports 

 w r ere only 797,763 cwt., viz. 727,420 cwt. plantation-coffee and 

 70,343 cwt. native coffee. The average annual deficiency in crop, 

 owing to the presence of leaf-disease in Ceylon, is estimated 

 to represent a loss of not less than £2,000,000. 



During the present year (1879) an earnest and, it is to be 

 hoped, successful attempt has been made in Ceylon to find means 

 for checking the ravages of the disease. A leaf-disease inquiry 

 was appointed by the local Government ; and a series of experi- 

 ments were instituted, with the cordial cooperation of the Plan- 

 ters' Association and the Chambers of Commerce. As during the 

 inquiry several points of interest have been noticed bearing upon 

 the structure and habit of the Hemileia, these are described, 

 with the view of supplementing the information already laid 

 before the Society on a subject of so great and increasing 

 importance. 



In Mr. Abbay's paper just mentioned, the chief points added 

 to our previous knowledge of the fungus consisted in determining 

 that the fruit was composed of sporanges containing a number of 

 sporidia or spores, and that when grown under artificial condi- 

 tions, the mycelium of the fungus very frequently produced coni- 

 dioid forms of fruit, termed by Dr. Thwaites in 1874 " secondary 

 spores." These latter were produced " in the form of radiating 

 necklace-shaped strings of spherical bodies of uniform size, closely 

 esembling the fructification of an Aspergillus." Mr. Abbay 



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