238 PHYTOPHTHORA MEADII n. Sp. ON HEVEA BRASIUENSIS 



Cultures. 



The first culture of the PhytopJuJiora was got by sh'ghtly scraping 

 the mycehum and sporangia from the surface of an infected leaf, shaking the 

 scraping in a little sterile water, and plating the material in French-bean- 

 agar. A sporangium that had germinated as a conidium was removed on the 

 second day and placed in a French-bean-agar sloped tube. Subsequently 

 cultures were made in a similar mamier from other leaves and from fruits in 

 the growing seasons of different years. They were also made from shavings 

 from the living tissue close to the line of division between dead and living 

 tissues of a branch that had died back and from a spot of bark-rot. The tissue 

 was placed in a moist chamber and from the mycelium and sporangia developed 

 on it cultures were made as before. Thus all the cultures started from single 

 sporangia. Transfers were made as a rule by transferring mycelium from 

 tube to tube. Though the fungus grows somewhat better on other media 

 still French-bean-agar was invariably used throughout, as it was the first 

 medium found on which the fungus grew readily. 



Groivth in oiltvre media. Six tubes of each medium freshly prepared were 

 inoculated at the same time and kept under the same conditions. One of each 

 was used for examination during the period of observation. In agar-agar 

 there was very slight submerged growth after two days and it very slowly 

 increased, and at the end of a month there was a little growth on the surface. 

 In glucose-agar the gTowth was similar to that in agar-agar, but it advanced 

 along irregular lines and the submerged hyphse were richly branched and 

 irregularly swollen. In carrot-agar the growth was mostly submerged with 

 sparse hyphae projecting slightly above the surface. On the 5th day it had 

 advanced about 1 centimetre, and by the 9th day the aerial hyphae began to show 

 more copiously and gradually increased till at the end of a month there was a 

 fair amount of mycelium all over the surface. In potato-agar the growth was 

 like that in carrot-agar but advanced at first a little more rapidly. The aerial 

 hyphse, however, did not appear to such an extent and at the end of the month 

 were still scanty. On ZTerm-leaf-agar the growth at first was slight and sub- 

 merged, but from the ninth day it increased more rapidly and hyphae appeared 

 on the surface. By the fourteenth day the whole surface was scantily covered 

 with mycelium. At the end of a month the mycelium was a dull felted mass 

 on the surface. On French-bean-agar the growth of aerial hyphae was good, 

 reaching 1 centimetre on the second day, 5 centimetres on the ninth, and 

 9 centimetres on the fourteenth day, covering the whole surface of the medium 

 in the sloped tube and advancing up the sides. The mycelium was white and 



