JEHANGIR FARDUNJI DASTUR. 193 



vertically opposite the stalk, but some sporangia have been found 

 with two (Plate IV, Fig. 36). In such cases the discharge of 

 zoospores does not necessarily take place through the apical papilla. 



Sporangia fall off from their sporangiophores with or without 

 any vestige of their stalks. Sporangia from a healthy culture, 

 when suspended in water and in ordinary day-light, discharge 

 their zoospores within five minutes. Sporangia from cultures made 

 in May and June 1912, when the temperature was very high, did not 

 discharge their zoospores so readily. They required to be suspended 

 in water for half an hour to make them discharge their zoospores, 

 but when they were suspended in water and kept in an incubator at 

 25° C, zoospores were emitted in five minutes. The same result 

 was obtained by adding a small piece of ice to water containing 

 sporangia. Cultures made in these hot months were occasionally 

 daily put in an incubator at 25° C. They produced sporangia 

 luxuriantly, which discharged their zoospores in ordinary tap water 

 or distilled water in five minutes at room temperature. Submerged 

 sporangia from French-bean juice agar and oat juice agar discharge 

 their zoospores even when embedded in the media. These zoospores, 

 after leaving the sporangium crawl about for a few seconds in the 

 film of water expressed from the agar before rounding themselves 

 off, and germinate like other zoospores. Light seems to influence 

 the formation and emission of zoospores. A dozen healthy hanging 

 drop cultures were kept in a dark cupboard and a dozen similar 

 cultures left on the working bench in ordinary day-light. Within 

 half an hour all the mature sporangia in the cultures left on the 

 bench had discharged their zoospores while there was no change in 

 those kept in the dark ; but the next day sporangia in these cultures 

 had germinated conidially, giving a highly branched mycelium 

 (Plate III, Fig. 1). Both these sets of cultures were kept under ob- 

 servation for three days. The cultures kept in the dark formed no 

 new sporangia but in those kept on the working bench the sporangia 

 that had not discharged their zoospores had germinated conidially 

 and bore secondary sporangia (Plate IV, Fig. 37) ; and the new 

 plants got by germination of zoospores had also formed sporangia. 



