BUTLfeR AND KULKARNt 24l 



thorn, the spores being fully demarcated and provided with cilia 

 before they emerge to the outside (PI. IV, Fig. 3). Often two or 

 more zoospores remain attached, in extreme cases forming a mass 

 in which the individual spores cannot be distinguished. At least 

 ten spores must have been included in some of the masses expelled 

 from feeble or contaminated cultures. These masses are provided 

 with several or numerous cilia but always appear to break down 

 and disintegrate without secreting a wall. 



The influence of temperature on zoospore formation is marked. 

 A portion of a culture was divided into two parts, one of which was 

 placed in tap water in the cool incubator at 25°C, the other kept in 

 the laboratory at 32°C, both being equally illuminated. Examined 

 after an hour, the former was found to be discharging freely, the latter 

 not at all. The higher temperature, however, merely inhibits zoospore 

 production, without affecting the power to produce them when suit- 

 ably cooled, as part of a culture which had remained in water for two 

 hours at 30°C, without any but a very few sporangia having discharg- 

 ed, gave very numerous zoospores when placed in the cool incubator. 



Light does not appear to influence the formation of sporangia 

 when temperature conditions are suitable. A culture kept in the 

 dark at 25°C. for a month from the date of sowing was found as 

 fully provided with sporangia as any of the cultures in the labor- 

 atory. This differs from the results got by Dastur 1 with Pit. 

 parasitica, where cultures kept in the dark remained sterile. No 

 observations were made on the effect of light on the emission of 

 zoospores but Coleman and Dastur have found that a certain amount 

 of light is necessary for this process in Ph. omnivora vsx.AreccB and 

 Ph. parasitica respectively. 



III. Cultures of Piiytophthora Colocasi-E 2 . 

 In recent years several species of Phytophthora have been 

 successfully cultivated on artificial media. In the present 



i Dastur, J. F. On Phytophthora parasitica nov. spec, a new disease of the Castor oil 

 plant. Mem. Dept. of Agric. in India, Bot. Ser. V, No. 4, 1913. 



- We are indebted to Mr. J. V. Dastur, First Assistant in the Mycological Section, Pusa, 

 for much assistance in obtaining cultures of the fungus. 



