TILLETIA TRITICI 



257 



while the thickness of the agar had become reduced from G mm. 

 to 4 mm. 



From the result of the experiment just described it is evident 



Fig. 129. — Tilletia tritici. The production and discharge of basidiospores in 

 relatively dry air (relative humidity 30-35). The oatmeal-agar plate 

 here shown was inoculated by falling basidiospores and, after about 

 seven days, it bore vigorously-growing masses of mycelium. It was 

 then uncovered, inverted, and suspended in the dry air of the laboratory 

 in the manner shown in Fig. 128. Basidiospores continued to be pro- 

 duced and to form a spore-deposit on a slide for 12-24 hours. During this 

 period, the agar lost so much water by evaporation that it cracked across 

 and shrank from the side of the Petri dish, as shown in the photograph. 

 Natural size. 



that, so long as the mycelium of Tilletia tritici can procure sufficient 

 water from its substratum, it continues to develop and discharge 

 basidiospores in a normal manner, even in extremely dry air. 

 Doubtless, this fact has some significance for the production of 

 basidiospores under natural conditions. 



VOL. v. s 



