256 PflYTOPHTHORA MEADtl n. Sp. ON HEVEA BRASILIENSt3 



lies loose within the oogonium, its diameter being from 0"5 to 0"8 that of the 

 latter. The measurements of the oogonia of the two fungi are fairly close, 

 but the oospores of P. Meadii are much smaller. Von Faber^ gives the measure- 

 ments of P. Faberia.& 22 — 45/^,, Rorer as 33 — 40/a, and Coleman as 22*4 — 41*2/x, 

 while those of P. Meadii are for oogonia on fruits 22 — i8fi, and for oospores 

 16 — 32)U.. In P. Faheri no antheridia have been seen, unless perhaps by Rorer j^ 

 who in Plate XVII, fig. 14, of his paper, figures an " oospore showing oogonium 

 wall and antheridial branch," and if this be a true antheridium, then it is of 

 quite a different type to that of P. Meadii in which, besides, an antheridium 

 is invariably present. The main differences then between the two fungi are 

 that the oospore of P. Faheri almost completely fills the oogonial waU, and 

 that no antheridium is present, while in P. Meadii the oospore lies loose within 

 the oogonial wall, and a persistent antheridium is invariably present. The 

 differences are so distinct that the two cannot be regarded as of the same species. 



Cross inoculations were made with P. Meadii and P. Faheri on the fruits 

 of cacao and Hevea. Fruits of both were washed in distilled water and rubbed 

 well with soft cloths. They were again washed individually in sterile distilled 

 water and wiped with sterile cloths. Each cacao fruit was placed on a glass 

 stand in a potato-dish, into which a Uttle water was placed to form a moist 

 chamber, while four Hevea fruits at a time were placed similarly in potato- 

 dishes. The glass dishes and the water were sterihzed before being used. All 

 the fruits were well growii, but not quite mature ; they were all collected 

 on the same afternoon from a small isolated Government garden, where neither 

 P. Meadii nor P. Faheri has ever been found. They were treated in precisely 

 the same manner, kept under the same conditions, and inoculated from the 

 same culture of P. Meadii and of P. Faheri. The bruising of some of the fruits 

 was done by making a few criss-cross lines by means of a sterile knife-point 

 on an area of about half a square centimetre. Each of the two cultures was 

 immersed in distilled water, and when the discharge of zoospores became active, 

 a minute piece of the myceUum was placed in a large drop of water on each 

 of the respective fruits. Several times pieces of the mycelium taken were 

 placed on a slide instead of on the fruit, and examined to see that they contained 

 bursting sporangia which they did. The table indicates how long after the 

 date of inoculation hyphse, sporangia and discoloration of the surface of 

 the fruits were observed to be present. 



1 voa Faber, F. C. " Die Krankheiten uad Parasiten des Kakao-Baumes. Arbeiten a.d. 

 Kais." Biol. Anst. fur Land-und Fonstwirtsckaft, VII, pp. 193—210, 1910. 



2 Rorer, J. B. " Pod-Rot, Canker, aad Cliupou-Wilt of Cacao caused by Phyiophihora sii."' 

 Bull. Dept. of Agric, Trinidad, IX, No. 65, pp. 79—120, 1910. 



