H. WORMALD 



95 



later two others emerged, leavino 11 which were still within the spor- 

 angium after 15 minutes. 



The zoospores which escape first (to about 10 in number) are difficult 

 to count for they are expelled in an almost continuous stream and cling 



Fis. 1. Zoospores escaping from a sporangium, witli the formation of a vesicle. 



together, surrounded by a vesicle, just outside the mouth of the spor- 

 angium, for about a second before suddenly dispersing (Fig. 1). The 

 vesicle is derived from the hyaline plug forming the papilla; this is 

 pushed out as a spherical transparent body which rapidly increases in 

 size as the zoospores rush in. When its diameter is about equal to the 



