Arthur: Nineteen Years of Culture Work 19 



names, and every effort was consequently put forth to make head- 

 way into this obscure maze of forms. The first success was in 

 1902 with a form on Elymus virginicus and aecia on Impatiens, 

 which became Puccinia Impatientis (Schw.) Arth. The work 

 opened up slowly. In 1903 a false move was made in connection 

 with the rust on Bromus, but the year following this rust was 

 shown to have aecia on Clematis virginiana. 10 



In 1907 Puccinia Agropyri E. & E., as it occurred in Colo- 

 rado on Agropyron, was found to go to Clematis ligusticifolia, a 

 connection that had been demonstrated by Dietel with European 

 hosts fifteen years before. The following year Puccinia cinerea 

 Arth. on Puccinellia was grown on Ranunculus Cymbalaria, a 

 rust from Koeleria cristata on Mahonia, from Bromus on Thalic- 

 trum, from Agropyron on Aquilegia, the last three being de- 

 scribed as new species. In 191 5 aecia on Hydrophyllum from 

 Utah were made to grow on Agropyron and Elymus, giving rise 

 to uredinia and telia similar to those from the Ranunculaceous 

 aecia, but believed to constitute a distinct species. In 1916 

 another rust on Koeleria cristata was grown on Laciniaria under 

 the name P. Liatridis (Ell. & And.) Bethel. Repeated attempts 

 were made to find the aerial host of the common leaf rust of 

 wheat, P. triticina Erikss., but without success, although there 

 were many indications that pointed to a Ranunculaceous host, and 

 especially to Clematis or Anemone. It was thought that a favor- 

 able trial on Clematis Flammula would give a measure of success. 

 At any rate it was believed to be one of the numerous races of 

 the subepidermal leaf -rust of grasses, P. Agropyri, with Ranun- 

 culaceous hosts for its aecia. 11 



The series were discontinued before the study of the subepi- 

 dermal forms was completed, but ten of them had been connected 

 with their aecia. The conviction had been growing for some 

 time that some of these ten names represented races of Puccinia 

 Agropyri, rather than independent species, as was stated in dis- 

 cussing the cultures of 1912. When the manuscript was pre- 



10 For a full account and explanation of the mistake of 1903 in supposedly 

 connecting aecia on Dirca with the Bromus rust see Journal of Mycology 11 : 

 62-63. 1905. 



11 Mycologia 9 : 276. 1917. 



