294 



The North American Cup-Fungi 



pendicuIarK- from the surface of the culture medium (Text- 

 fig. 5). Then each hypha, beginning at its apex and proceeding 

 downwards, breaks up into a series of short cyHndrical cells which 

 become the oidia (Text-fig. 4). These oidia, when fulh' formed, 

 are loosely attached to one another and a chain of oidia may be 

 readily detached from the mycelium b\- a puff of air blown from 

 the mouth. The oidia adhere to an>' object which is brought 

 into contact with them. Those shown in Plate XIX, Fig. 4, 



Fig. 21. Oidia in Ascoboliis stercorarius (Bull.) Schrot. From Dowding. 



adhered to a glass slide which was lowered gently on to the 

 surface of a mycelium. 



"The oidia of A. stercorarius germinate readily in water, 

 dung, dung agar, or air saturated with water vapour, and in all 

 these media germination begins within twelve hours after the 

 oidia have been sown. 



"On germinating, an oidium first swells up to about eight 

 times its original volume and, in so doing, becomes barrel-shaped 

 and vacuolated (Text-fig. 6). Then it puts out either one or 

 two germ-tubes from its sides or ends (Text-figs. 6-10). In a 



