JEHANGIR FARDUNJI DASTUR. 203 



coloured oogonia growing in oat juice agar, look similar to those of Ph. 

 infestam found in the same medium by Clinton 1 , but they are much 

 smaller. The thick-walled oogonia of Ph. parasitica vary from 

 25 to 35/* in diameter, while those of Ph. infestam vary from 34 to 

 50/a in diameter. Though the oogonia from French-bean juice agar 

 are smaller than those from oat juice* agar, this difference in size 

 being due only to the nature of the two media, still the oospores 

 from both these media are of the same size. They vary from 13 to 24/* 

 in diameter as a rule from 15 to 20/*. The average of 60 measurements 

 gave a diameter of 18'6/a. They have a thick wall, about 1 to 2« in 

 thickness, and are spherical, smooth and hyaline. They have a 

 homogeneous mass of protoplasm, generally containing one or more 

 oil globules. 



The antheridia are hyaline, thin-walled and irregular in shape. 

 Those produced in French-bean juice agar are larger than those found 

 in oat juice agar. They are persistent ; even in very old cultures thev 

 have been found to remain attached to the oospore. The oospore 

 breaks or! from its antheridium when roughly manipulated. 



The oospores in oat juice agar are embedded in the medium and 

 are, as a rule, confined to those portions containing matted budding 

 hyphse, which are considered to store reserve material for the fungus. 

 These are invariably empty after the formation of the oospores. 

 Very often the oospore is completely entangled in the network of 

 those hypha). The oospores in French-bean juice agar are embed- 

 ded in the medium, but they are not restricted to any particular 

 portion of it. They are found mixed up with sporangia and 

 " resting " conidia. 



The oospores of Ph. infestam " are more likely to be found 

 in the upper and drier part of the tube' 2 *' but the oospores of Ph. 

 parasitica have invariably been found in the lower and moister part 

 of the tube and never in the upper and drier. There is as much 

 variability and uncertainty in the production of these oospores as 

 Clinton found in the production of those of Ph. infestam. Some 



i Clinton, G. P. loc. tit., 1909-1910, p. 772. 



2 Ibid., p. 705. 



