244 PHYTOPHTHORA MEADII n. Sp. ON HEVEA BRASILIENSIS 



80 readily. Similar results have been got in ditt'erent years on fruits both from 

 the West Coast and from an estate on the Nilgiri District where the fruit-rot 

 does not occur. Younger fruits from the size of peas upwards have been 

 infected in exactly the same way. 



Inoculation on to other plants. In nature this Phytophthora has been found 

 only on Hevea brasiliensis. Artificial infections have been induced, however, 

 on Manihot Glaziovii and Ricinus communis. The inoculative material was 

 mycelium with discharging sporangia from a culture on French-bean-agar 

 except in two plants of Ricinus where it was from a Quaker-oats-agar culture. 

 The plants were grown at Coimbatore from seed and were not exposed to 

 outside infection before the experiment. The 8 inoculated Ricinus leaf-buds 

 became infected while the 4 controls remained healthy, and the 4 inoculated 

 leaf-buds of Manihot became infected, while the 3 controls remained healthy. 

 The leaf-bud and three or four leaves on the brianch behind it were inoculated 

 in each case. The infected leaves show a discoloured spot on the 2nd or 3rd 

 day, and the spot gradually extends till about the 7th or 8th day part or all 

 of the leaf is flaccid and Unip and al-rial hyphse and sporangia are found under 

 moist conditions. They behave very much as do the Hevea leaves. When 

 young plants are used the fungus may pass down the stem and kill them as it 

 does in Hevea seedlings. Twenty-three iruits of Hevea and 27 fruits of 

 Manihot were washed in 1 per cent, corrosive sublimate, then in distilled 

 water, wiped dry with sterile cloths and placed in moist chambers. Of the 

 IG Hevea fruits inoculated 13 became infected by the 6th day and 3 did not, 

 while of the 7 controls 6 were healthy and one was mouldy. Of the 21 Manihot 

 fruits inoculated 12 became infected by the 6th day and 9 did not, while of 

 the 6 controls 5 were healthy and one had a spot of mould on the last day. 

 The infected fruits of Manihot Glaziovii become discoloured and rot in the 

 same way as do those of Hevea, but they do not decay so quickly. 



The fungus 



The hyph* are hyaline, and vary much in diameter ; they usually 

 measure from 2 5 to 6/ot across, but may be up to 10/x, especially in the 

 pith and in vigorously growing cultures where the branching is irregular and 

 profuse. Transverse wal's are sparsely formed ; they occur to cut off the 

 reproductive organs and to cut off an empty part of a hypha from the part 

 containing protoplasm, and this may happen very early in the life of an indivi- 

 dual fungus. Cross walls are sometimes irregularly thickened. Differentiated 

 haustoria as such have not been seen. A branch that has entered a cell may 



