Arthur: Cultures of Uredineae in 1908 229 



the assistance rendered by Dr. Wm. Trelease, of the Missouri 

 Botanical Garden, St. Louis, Mo., who sent plants of Porteran- 

 thus stipulatus on which the new cedar rust was sown. The 

 writer extends his warmest thanks to the above individuals and 

 to others who have assisted in the year's investigations. 



During the present season 204 collections of material with rest- 

 ing spores and 26 collections with active spores were employed, 

 from which 565 drop cultures were made to test the germinating 

 condition of the spores. Out of the 204 collections with resting 

 spores 99 could not be brought to germination although seemingly 

 in perfect condition leaving 105 collections of available material. 

 These 105 collections with resting spores and 26 with active 

 spores belonged to about 60 species of rusts. Altogether 321 

 sowings were made, employing for the purpose 114 species of 

 hosts, these being grown in pots, so that the work of attempted 

 infection could be conducted wholly in the greenhouse. 



The results of this work are given in the following paragraphs, 

 and are divided into negative results, positive results with species 

 whose life cycles have already been ascertained by the writer or 

 other investigators, and positive results with species whose life 

 cycles are now first placed on record. 



Negative results : — Quite a number of collections gave good 

 germination of the spores, but no infections were secured. The 

 following may be recorded to serve for reference in future 

 studies : 



1. Puccinia on Car ex pennsylvanica L., collected at Red 

 Cloud, Neb., by Rev. J. M. Bates, was sown on Arabis Holboellii, 

 with no infection. Similar material was sown in previous seasons 

 on thirty-eight other species of hosts. 4 



2. Puccinia vulpinoidis Diet. & Holw., on Carex vulpinoidea 

 Michx., collected at Newark, Del., by Mr. H. S. Jackson, was 

 sown on Viola cucullata, Chelone glabra, Aster paniculatus, Am- 

 brosia trifida, Cacalia reniformis, Laciniaria punctata, Rudbeckia 

 laciniata and Senecio obovatus. A similar collection made at 

 London, Ontario, by Mr. J. Dearness, was sown on Cailirrhoe 

 involucrata and Rudbeckia laciniata. Still a third collection made 



4 See Jour. Myc. 10: 10. 1904; 11: 51. 1905; 12: 12. 1906; 13: 191. 

 1907 ; and 14: 9. 1908. 



