Infection of Host-Plants by Ustilaginccr. loi 



experiments in which he applied the teleutospores to the 

 young plant. F. von Waldheim was equally unsuccessful. 

 Kuhn asserts that he found that, if too many germ-tubes 

 entered an embryo plant, they developed into spore-forming 

 hyphse 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 U. segetiim 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. scgetmn in 

 nahrlosung and dipped the young embryos in it ; watered 

 the grain, after it was planted, and before it came up, with 

 nahrlosung, 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 glumellse 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. T. trilici 

 matures its teleutospores at the same time that the wheat- 

 plant matures its fruit ; but with U. segetum the case is 



