82 Infc(:tioit of Wlirat bfi means of Rusted Grains 



Of the rust-infected grains, one portion was subjected to the hot- 

 water treatment, the other portion left untreated. As controls, similar 

 portions of grain on which no sori could be detected were used, part 

 being treated and part untreated. All were germinated at a temperature 

 of 15-18° C, and when the shoots were about half an inch long, planted 

 in pots which were kept in a glasshouse. There was no observable differ- 

 ence in the germination of the rusted and healthy grains. At intervals 

 during germination and growth seedlings were removed and portions 

 of them fixed in Flemming's weaker solution, embedded and sectioned. 

 The plants were under observation for a period of three months, during 

 which time no rust appeared. 



Sections of the infected grains showed that many of the numerous 

 teleutosori at the hilum end were internal sori. In the germinating 

 grains there was no indication of any development of the rust mycelium 

 underlying the sori; furthermore, it had every appearance of being a 

 dead mycelium as described by Hungerford. In many instances, irre- 

 spective of whether the original grain was rusted or healthy, treated or 

 untreated, fungal hyphae were present in the developing seedling. They 

 were generally of an intracellular nature. In one instance a Fusarium 

 type of spore was noted in a mass of mycelium growing on the outer 

 layers of the scutellum, and in other cases the hyphae belonged to a 

 species of Helminthosporiiwi, spores of this type occurring close to the 

 outer masses of mycelium. Nothing in the nature of the " palmella-like " 

 developments reported by Pritchard {Phytojmtliology , 1911, i. p. 150) 

 was found. Cases were observed in which hyphae were present in the 

 outer layers of the base of the seedling stem, but they were larger than 

 rust hyphae and were intracellular in growth. 



The above results are in close agreement with those recorded by 

 Hungerford and further serve to show that it is extremely unlikely that 

 rust myceHum in wheat grains brings about infection of the plant. The 

 mycelium of other fungi is however often present in the developing 

 plant and it might be mistaken for that of a rust. 



{Received March ith, 1921.] 



