438 
the surface of the stem, and on the inner surface of the sheaths, 
where it assumes a dark brown colour, and forms a somewhat thick 
felt that can be scraped off. The minute black fruits may be found 
nestling in this felt of mycelium; they also occur on the root. 
ccording to McAlpine,* wheat is the only cereal attacked by this 
fungus in Australia ; “the oat grows well in Take-all patches, and 
is not attacked by the fungus, hence it is recommended for starving 
it out.” This statement, however, does not hold good for this 
country, as specimens of oat plants attacked by Ophiobolus graminis 
were sent to Kew from Corwen, N. Wales, for determination 
during the present season. The diseased oats showed the “ White- 
head” phase, with silvery, empty glumes, and the base of the stem 
and root with a copious development of blackish, superficial myce- 
lium. The fruit of the fungus was present, setting aside all doubt 
as to the identity of the parasite. The crop in this instance was 
seriously affected, the diseased plants occurring in scattered 
es. A field of wheat near Shere, in Surrey, was also badly 
attacked by the ‘ White-heads” condition of this disease. 
conditions for growth, in a hanging-drop, slender colourless threads 
f the dark coloured 
plants, both oats and wheat, were yellow and drooping, and an 
examination revealed the presence of the characteristic dark- 
rome ar and at the end of four days germ-tubes were 
observed piercing the cell-wall of the root-hairs, and entering into 
without fail, From what has been 
