TILLETIA TRITICI 



211 



etc., may well have been due to these investigators not having 

 sufficiently ventilated their cultures. 



Since 1925, the violent discharge of the secondary conidia with 



Fig. 101. — The grains of two ears of Common Wheat plants 

 which were parasitised by Tilletia tritici. Usually, in an 

 infected plant, all the grains are invaded by the mycelium; 

 but, here, some of the grains (the darker ones) are bunted, 

 i.e. converted into smut-balls, whilst other grains (the 

 lighter ones) are quite sound. Material prepared and 

 photographed by I. L. Conners at the Dominion Rust 

 Research Laboratory at Winnipeg. Slightly less than 

 natural size. 



drop-excretion in Tilletiaceae, other than Tilletia tritici, has been 



observed : by Buller and Vanterpool in T. laevis : by Vanterpool 



in T. horrida, T. hold, and T. asperifolia : and by Hanna x in 



1 W. F. Hanna, personal communication. Observations made at the Dominion 

 Rust Research Laboratory, Winnipeg. 



