274 Journal of Agricultural Research voi. xjx, no. 6 



From all appearances the rust mycelium was dead in the sori of the 

 germinated kernels shown in Plates 46 and 47. The same was true of 

 the rust mycelium in wheat kernels that had been stored for some time. 

 All such mycelium was devoid of normal protoplasmic content. This 

 fact together with the apparent inability of this mycelium to spread to 

 the developing seedling indicates clearly to the writer that this mycelium 

 was dead. In fact, only in fresh kernels which were not fully matured 

 were any living rust myceHa found. Numerous efforts were made also 

 to germinate the teliospores found in sori upon the hilar portions of wheat 

 kernels, but all were unsuccessful. 



Hyphae of other organisms were present in abundance everywhere in 

 the pericarp of many kernels and in some cases were found to penetrate 

 the embryo. These hyphae were much larger and of an appearance 

 different from the rust hyphae found at the base of the sori in the hilar 

 portions of the kernels, as previously described. They penetrated 

 directly through the cell walls of the host and broke down the cell struc- 

 ture to a much greater extent than rust infection was found to do. Plate 

 48 shows an oblique longitudinal section of a secondary root of a wheat 

 seedling being invaded by this type of parasite. This was probably some 

 species of Helminthosporium, for typical Helminthosporium spores were 

 found on the germ end of the kernel from which this section was made. 

 Mycelium of the same type was found in the root, stem, and sheath of 

 a number of seedlings which were grown from kernels of wheat having 

 a distinct browning of the hilar ends somewhat similar to the general 

 appearance of rust-infected kernels. It seems not entirely unlikely, 

 therefore, that the apparently similar myceUum referred to by Pritchard 

 {21) may have been of this type, especially since he states that the 

 mycelium he noted also was intracellular. 



The writer did not find any " palmella-like " developments from the 

 teliospores, as described by Pritchard. However, no seed over i year 

 old was used, and since Pritchard used seed 5 years old this may to some 

 extent account for the difference. 



SUMMARY 



(i) Uredinia and telia of Puccinia graminis triiici Erikss. and Henn. 

 have been found embedded in the pericarp on the hilar end of kernels 

 of wheat and sometimes along the ventral groove as far up as the middle 

 of the kernel. Infected kernels have black hilar ends, and groups of teHa 

 appear as shining black specks under either the hand lens or the binocular 

 microscope. 



(2) Only a small percentage of infection was found by examination 

 of the hundreds of samples of wheat from the crops of 191 5 and 191 6. 

 A little over i per cent was the largest quantity found in any sample. 

 The durum wheats were found most commonly infected. 



