JEHANGIR FARDUNJI DASTUR 235 



The thickening, commonly found on septa of Ph. Colocasice Rac.^ and 

 Ph. -parasitica Dast. is usually wanting. Very often branches have been found 

 arising through septa, growing for some distance within the empty cells outside 

 the septa and then coming out by perforating the wall as in Ph. parasitica 

 and Fusarium tuherivorum Wilcox and Link^ (Fig. 2). Such branches have 

 been observed to form sporangia outside the parent hypha. 



Sporangia and zoospores agree in measurements with those of the 

 castor fungus. The formation of secondary sporangia in the Vinca fungus 

 is common. They are either stalked or sessile. Sessile secondary sporangia 

 have always been found to arise from the papilla, but stalked ones arise not 

 necessarily from this place. 



Zoospores sown in water, after coming to rest, germinate in less than half 

 an hour by giving out one or as many as four germ-tubes. The fungus upon 

 castor has not hitherto been observed to give more than two germ-tubes. " The 

 germ-tube either grows into a thin hypha, branched or unbranched, or becomes 

 swollen. The germinating zoospore, in the course of six to twenty-four hours, 

 commonly bears a sporangium at the end of its germ-tube (Fig. 1). This mode 

 of germination has been observed by Raciborski^ in Phytophthora Colocasice 

 and by me in Ph. parasitica on castor. The sporangia borne on germ-tubes 

 are pear-shaped and measure 13— 20x10— 15^. They germinate either by 

 discharging their zoospores, which are from 2 to 6 in number and as big as 

 those produced by sporangia from nutrient media, or by giving rise to 

 germ-tubes or to secondary sporangia. 



Resting conidia resemble those of Ph. parasitica in all respects, except 

 in size ; the former are smaller, measuring 10 — 42/x in diameter. 



Accoiding to Klebs,* Oedogonium can be readily induced to form 

 antheridia by regulating light, amount of water and the nutrient quality of the 

 medium used. It has not been found possible to induce the development 

 of sexual organs of this fungus by any systematic method, for it is exceedingly 

 difl&cult to determine the predisposing factors. Oospores were found first 

 in one of the six French bean juice agar tubes and a fortnight later in another, 

 all of which had been inoculated the same day with mycelium from a culture 

 growing on Quaker-Oat agar. These six French bean juice agar tubes belonged 



1 Butler, E. J. and Kulkami, G. S. Studies in Peronoaporaceas. Mem. Dept. Agric. 

 India, Bot. Ser. V, No. 5, 1913. 



2 Wilcox, E. M., Link, G. K. and Pool, V. W. A dry rot of the Irish Potato tuber. 

 Nebraska Agri. Expt. Sta. Res. Bull. No. 1, 1913. 



8 Raciborski, M. Parasitische Algen und Pilze Java's I, 1900. 



4 Klebs, G. Die Bedingungen der Fortpflanzung bei einigen Algen und Pilzen, 1896. 



