JEHANGIR FARDUNJI DASTUR. 223 



de Barv, Klebahn and Himmelbaur have found oospores being 

 developed in the ordinary way. viz., by the sexual organs arising 

 either from two different branches or from two different stalks of the 

 same branch and the antheridium meeting the oogonium to fertilise 

 it by means of a fertilising tube, while the formation of a hypo- 

 gynous antheridium was only occasionally met with by Hartig. 

 On the other hand in our Phytophthora this customary mode of 

 development of the sexual organs has never been found. Again 

 the oospores are smaller than those of Ph. omnivora. De Barv 

 does not give any measurements of oospores of Ph. omnivora but 

 he says that they fill two-thirds or four-fifths of the oogonium, which 

 ranges between 24 and 30// in diameter. Klebahn gives no measure- 

 ments at all. Himmelbaur found the oospores of Ph. Fag/ to be 

 yellowish and ranging between 22-30M in diameter, and those of 

 Ph. cactorum brownish and measuring 30-40> in diameter. While 

 the oogonia of the castor Phytophthora measure as a rule 18-25/u. 

 on an average 23'8^, if we exclude the secondary thickness 

 formed on the walls of oogonia found in oat juice agar ; and the 

 oospores are hyaline and measure 15-20> in diameter, on an average 

 18'6^. The oospores of the castor Phytophthora being both lateral and 

 intercalar would seem to offer a point of difference from Ph. omnivora, 

 but much importance cannot be given to this ; both Hartig 1 and 

 Klebahn 2 have found them to be mostly terminal in Ph. Fagi while 

 Himmelbaur 3 , who had the pure culture of this fungus from Klebahn, 

 found them to be mostly intercalar. 



From Coleman's figures it cannot be definitely determined 

 whether or not the antheridium of Ph. omnivora, var. Arecce con- 

 tains the oogonial stalk within it ; from his description of the mode 

 of fertilisation it is quite evident that it takes place by means of a 

 fertilising tube, which has never been found in the Phytophthora on 

 castor. Again the oospores of the former are much larger ; they 

 measure 26-307* in diameter. 



1 Hartig, R. Inc. ril., p. 49. 

 • Klebahn, H. loc. cit., p. 72. 

 8 Himmelbaur, W. loc. cit., p. 50. 



