160 Ustiiliim Zonata [Lev.) Sacc. on Hevea Brasiliensis 



cations in the conidial stage have been found showing traces of insect 

 markings; whether the latter were feeding on the spores is doubtful, but 

 it was obvious they had spent some time upon the surface, judging from 

 the intricate tracings. 



Several cases of old trees hollowed by White ants and attacked by the 

 fungus have been found (PI. IV,fig. 8). These trees were all twelve years old ; 

 some had been successfully treated with the White-ant pumping machine 

 at the age of eight years. The number of trees found attacked by W^hite 

 ants and U. zonata is comparatively small when compared with those 

 attacked by boring beetles and U. zonata, or the number of old trees 

 suffering only from the fungus attack. In a consideration of treatment 

 and spread of the fungus, the White ant question appears to be of minor 

 importance. 



DESCRIPTION OF THE FUNGUS. 



The development of the fruit-bodies of U. zonata has been carefully 

 studied in the laboratory. Brooks' (i) description of Malayan specimens 

 is incomplete because up to the time of his departure he had not seen the 

 fructifications in the early stages. It may be stated here that the Malayan 

 specimens correspond in every respect to the description given by 

 Fetch (4) for those of Ceylon. 



The common fructification commences as a small yellowish-white 

 plate closely adpressed to the bark. The plate increases in size and the 

 surface darkens to a greenish-grey colour. This change in colour is due 

 to the formation of a thick conidial layer. In the Laboratory this stage 

 persists for about a week, and during this period the stroma is soft and 

 easily cut. Owing to the disappearance of the conidial layer, the stroma 

 becomes darker; as it ages it takes on a leathery consistency and ulti- 

 mately becomes quite brittle and black. Typical young specimens in the 

 field show a well-defined zoning on the surface (PI. IV, fig. 7 and Pl.V, fig. 9) 

 but those developed in the Laboratory did not show a conspicuously zoned 

 surface. When fully developed the plate-like fructifications are several 

 inches in diameter. A number of these plates may fuse together; large 

 plates formed by fusion of smaller ones have been found covering an 

 area of the stem three feet in length and nine inches broad. 



When the flat plate-like fructifications are broken across, the tissues 

 are found to be arranged in distinct layers. The accompanjring diagram 

 (after Brooks) illustrates the different layers. 



On the upper surface (a) represents the remains of the conidial layer. 

 Brooks did not observe the conidial layer in the specimens obtained by 



