TILLETIA TRITICI 



249 



is almost vertical, an angle of only about 1° being made between it 

 and a vertical line. The agar surface thus comes to look upwards 

 very slightly. Under these conditions, as the basidiospores are 

 shot away from their sterigmata on the 

 piece of inoculum, they settle on the sur- 

 face of the agar all down the slope. After 

 the slope has been thus seeded with basidio- 

 spores for about two days, it is placed 

 horizontally with the surface of the medium 

 facing upwards. The new mycelia derived 

 from the basidiospores which settled on the 

 slope soon begin to discharge a new crop of 

 basidiospores which fall on to the agar and 

 there germinate. Thus, in the course of 

 about two weeks, a white mat of mycelium 

 comes to cover almost the whole of the 

 surface of the slope (Fig. 121). 



The spore-fall method has been applied 

 with success to making cultures on agar 

 media in 150 cc. conical flasks. A test-tube 

 culture, like that just described, is held over 

 the mouth of the flask for 2-3 hours until 

 a sufficient number of basidiospores have 

 fallen into the flask. The test-tube is then 

 removed and a sterile cotton-wool plug is 

 placed in the mouth of the flask in the usual 

 way. 



Basidiospore-deposits. — As soon as it 

 had been discovered that the basidiospores 

 of Tilletia tritici are violently discharged, the 



Fig. 121. — Tilletia tritici. Large test-tube culture. 

 The piece of inoculum (agar with a mycelial mat) 

 is seen at the top of the malt-agar slope. After 

 inoculation the test-tube was maintained in an 

 upright position. The basidiospores shot from 

 the inoculum settled below all over the agar slope 

 and there germinated so that there is now a 

 mycelial mat covering the surface of the agar. 

 Culture about two weeks old. Natural size. 



