L[nfection of Host-Plants by Ustilaginee. 101 
experiments in which he applied the teleutospores to the 
young plant. F. von Waldheim was equally unsuccessful. 
Kiihn asserts that he found that, if too many germ-tubes 
entered an embryo plant, they developed into spore-forming 
‘hyphze and formed a “ brand-knot” in the sheath-node, and 
killed the young plant. All the experiments which I have 
conducted with a view of infecting the young plants of 
wheat, barley, and oats with UW. segetum have uniformly 
failed. I have attempted the infection in various ways: 
dusted the spores on the dry grain and planted it; soaked 
the grain in water, and then dusted it with the dry spores ; 
planted the grain in flower-pots, and dusted the spores 
thickly on the surface of the soil; the grain allowed to 
germinate, and applied the dry spores to the embryos just 
as they emerged from the seed-corn ; placed the teleuto- 
spores of U. segetum in water for twelve hours, and, when 
an abundant development of promycelial spores had taken 
place, applied the spore-charged water to the emerging 
embryos ; germinated the teleutospores of U. segetum in 
nahrldsung and dipped the young embryos in it; watered 
the grain, after it was planted, and before it came up, with 
nahrlésung, containing spores, but the result was uniform 
failure. Wolff has stated that the infection will not be 
successful if the infected plants be kept too moist at first. 
This point was attended to, but the result was the same. 
Mr. A. S. Wilson, however, has been more successful, for 
he showed me some oat-plants which he had artificially 
infected by removing the glumelle and applying the 
spores to that part of the kernel from which the embryo 
emerges; but he also informed me that he had many 
failures, 
But more than this remains to be considered. 7. trétc¢ 
matures its teleutospores at the same time that the wheat- 
plant matures its fruit; but with U. segetum the case is 
