W. MCRAE 241 



In other cases where the plants were kept under cover no tubes were used. On 

 the petiole the discoloration appeared on the 2nd to the Gth day and the leaf 

 fell on the 8th to the 11th day. Sectioning and incubating the discoloured 

 part showed that the fungus was like that in culture. The controls were 

 unaffected. 



(4) On the green branch a small cup of plasticine or of soft paraffin-wax was 

 moulded, and this held a small quantity of water into which the infective 

 material was put. Discoloration appeared on the 2nd to the 5th day. In 

 growing shoots, a week or two old, of young plants the part above the point of 

 inoculation bent over and hung down, while those a httle older remained erect 

 and gradually died in from 5 days to 2 weeks. This depends on the amount 

 of supporting tissue developed in the shoot. Discoloration sometimes passed 

 downwards below the cup, the leaves were shed one by one, and young plants 

 died down to the base. Sections showed the presence of hypha? of Phytophthora 

 in all the discoloured tissues, and on incubation for a day sporangia were 

 produced Uke those in culture. Green shoots of trees silied their leaves iunue- 

 diately above the point of inoculation, and then the whole upper part died ; 

 yet in some cases, though a part of the stem became discoloured round the 

 point of inoculation, the discoloration did not extend and the branch remained 

 quite healthy. Later on one of the latter was examined, and though there 

 were hyphaB within the tissues they could not be definitely assigned to 

 Phytophthora and on incubation moulds were produced. The controls 

 remained unaffected, 



(5) On the tapped surface. A small cup of plasticine was moulded against 

 a part of the tapped surface on a tree that had been tapped the same da\ . 

 Mycelium from a pure culture was kept for 24 hours in a watch-glass with a 

 little water. Before inoculation more water was added, and when the sporangia 

 were discharging freely a small piece of the mycelium with sporangia and zoo- 

 spores was transferred to the water in the cup. During the monsoon a small 

 flap of waxed cloth was tacked on the tree above the cup and hung down 

 over it about an inch. This was meant to prevent rain-water streaming down 

 the trunk from entering the cup too freely and washing out the infective 

 material. When the inoculations were done in less rainy weather this was 

 dispensed with. Tapping was stopped on all trees after they were inoculated. 



(a) 15 were inoculated and 8 showed the discoloration of the bark on the 

 7th day. The other 7 showed no sign and were re-inoculated as before on tbe 

 7th day. After 47 days 9 had bark-rot and G had not. The controls had no 

 rot, (6) At the end of the mouaoon lU were inoculated and 7 showed dia- 



