A. Sharples 167 



which quick travelling fungi, such as Diplodia cacaoicola (P. Henn) and 

 Corticium salmonicolor (Zimm.) proceed, and the hyphae of these fungi 

 are always specially noticeable in the vessels. C. salmonicolor is note- 

 worthy in this respect, for as it passes along the vessels the living cells 

 bordering them produce tyloses (2) in an attempt to stop the progress of 

 the fungus. The vessels in wood attacked by U. zonata seldom show these 

 ingrowths; Brooks (i) also calls attention to this absence of tyloses. 



BLACK LINES IN ROTTING WOOD. 



The tendency for fungi to produce black lines similar to those de- 

 scribed for U. zonata is a noteworthy feature in the tropics. All rotting 

 soft-wood logs on the plantations show these lines when the wood is cut. 

 These lines are an important diagnostic feature to the planter, and more 

 certain knowledge of the fungi forming lines in rotting soft wood on the 

 plantations is desirable. A special investigation is under weigh, results 

 of which are not yet to hand. 



INOCULATION EXPERBIENTS. 



The inoculations described by Brooks (i) indicate that the fungus will 

 easily enter the collar of a rubber tree through wounds, but cannot enter 

 a healthy unwounded tree. On very young unwounded seedlings, he 

 obtained successful artificial inoculations, but similar trials on woody 

 plants were unsuccessful. 



Usually a fungus is limited in its infective capacity to either the 

 aerial or underground portions of a plant, i.e. a fungus causing a root-rot 

 will not attack the stems and branches of a particular host, and vice versa. 

 A priori considerations lead to the conclusion that a wound parasite on 

 roots might easily attack branches through wounds, but experimental 

 evidence was desirable. The inoculation experiments to be described 

 settle this question, and also bring evidence to support the result arrived 

 at by culture experiments and field observations which proved that 

 U. zonata is the organism causing the rotting of the tissues in rubber 

 stems and branches attacked by borers. 



Roots were inoculated with the fungus ( U, s) isolated from the stem 

 and branches, and branches were inoculated with the fungus {U, r) 

 isolated from the roots. 



Expt. 1. ]^]ight seedlings were inoculated on 17. vi. 15. These plants 

 were six months old, and had developed a woody stem at and for about 

 eight inches above the collar. Four were inoculated with ( U, r) four with 

 {U, s). The inoculations were made by placing small pieces of rubber 



