THE AECIDIAL STAGE OF PUCCINIA GRAMINIS PKRS. 281 



Puccinia graminis Pers. But if the aecidial stage on the 

 barberry cannot be produced, and if this feature is a 

 requisite' 8 ) in the determination, then as Mc Alpine suggests 

 its identity with Puccinia graminis Pers. is not proved. 



Inoculation Experiments. 



(a) British Material. 



It was planned to attempt the barberry infections in 

 1919. In July of that year a number of species of Berberis 

 were kindly supplied by Mr. J. H. Maiden, f.r.s., Director 

 of the Sydney Botanic Gardens, and planted as a hedge at 

 the Sydney University; a few were also planted at certain 

 of the Government Experiment Farms. It was not until 

 the present year, however, that the work became possible. 

 In the meantime the plants had been attended to and had 

 become well established. 



In 1920, while the writer was at the Imperial College of 

 Science and Technology at South Kensington, attempts 

 were made to get Australian teleutospore material to 

 germinate in order to test it on barberries there. Rusted 

 straw was kept in a cool cabin during the voyage and other 

 material was sent through the post in the usual way. But 

 in all cases the spores failed to germinate upon arrival in 

 England. These results are in accord with those reported 

 by PIowright. (9) 



In March 1921, rusted wheat straw from Pembrokeshire, 

 Wales, was collected and forwarded by Mr. A. D. Cotton 

 of the Institute of Plant Pathology at Harpenden. It 

 showed abundant teleutosori of Puccinia graminis on the 

 sheaths and stems, and was in a viable condition upon 

 arrival in Sydney at the end of April. At this time two 

 plants of Berberis vulgaris, which had been cut back a 

 short time before, were putting out fresh young growth. 

 Small bundles of the rusted straw were suspended over one 



