Arthur: Cultures of Uredineae, 1899-1917 231 



of heteroecious species only three times was a discovery of al- 

 ternate hosts effected that was not the outcome of a previous 

 field observation. In two of these cases, that of Uromyces acu- 

 minatus (more properly U. Steironematis, see page 76,* Jour. Myc. 

 12: 25), and Puccinia Ceanothi (see page 196,* Mycologia 4: 27) 

 sowings were made on all available hosts in the greenhouse, re- 

 corded as bearing aecia, and in the case of P. fraxinata (P. peri- 

 dermiospora, see page 8,* Bot. Gazette 29: 275), a morphological 

 similarity was detected between aesciospores and urediniospores, 

 leading to successful cultures. 



Beginning with the immediate vicinity of Lafayette, Indiana, 

 the range of observations was extended to various parts of the 

 state, and in the ninth year of the work, 1907, to other states. 

 This year a trip was made to the foothills of Colorado, which 

 was repeated in 1908, 191 1 and 1916, observations being made 

 from Boulder to Trinidad, and once westward to Ouray and 

 Durango. Between 1908 and 1916 trips were made northward 

 to Wisconsin and Michigan, eastward to Maine and Pennsyl- 

 vania, to South Carolina, Alabama and Mississippi in the south, 

 and to Texas, New Mexico and Arizona in the southwest. So 

 far as possible places were selected where there were local col- 

 lectors, or where records showed that species requiring investi- 

 gation had at some time been secured. The chief collecting 

 grounds of Ellis in New Jersey, Ravenel in North and South 

 Carolina, Atkinson and Underwood in Alabama, and Kellerman 

 in Kansas were visited, and the collecting grounds of Schweinitz 

 at Salem, North Carolina, and Bethlehem, Pennsylvania, would 

 have been visited, if opportunity had favored. In this way many 

 obscure names in the literature were connected with living ma- 

 terial on which fresh and more extended studies, often including 

 cultures, could be carried out. By this method the attention 

 given to the genus Gymnosporangium was made to expand our 

 limited knowledge of a few species into an understanding of the 

 life history of some two dozen species and of their alternate hosts. 

 The effectiveness of the work with Gymnosporangium was 

 greatly enhanced by the special interest in it taken by my asso- 



* For explanation of these page numbers see p. 246 at beginning of the index. 



