Fraser: Cultures of Heteroecious Rusts 185 



germinated in a few days in a moist chamber. A sowing was 

 made on Abies balsamea and Tsuga canadensis on June 13 with 

 pycnia on the latter on June 20, and aecia on July i, but without 

 infection on the former. Another sowing on the same hosts on 

 June 17 gave pycnia on Tsuga canadensis on June 26 and aecia on 

 July 4 but without infection on Abies. A third sowing was made 

 with the same results. 



In the field the infected leaves of Rhodora had been placed 

 under two trees of Tsuga canadensis in dififerent places and in 

 both there was a most decided infection of the neighboring 

 leaves ; the trees of Tsuga that had been planted among the rusted 

 Rhodora also developed aecia, but Abies did not. The writer's 

 attention was now called to Arthur's description of Per. fructi- 

 genum (Bull. Torrey Club 37: 578. 1910) on the cones of Tsuga 

 ciniastrum minimum, and also to Spaulding's collection of aecia 

 on the leaves of the hemlock which he regarded as belonging to 

 this species (Phytopath. i: 94. 1911). Experiments were now 

 tried to determine if the cones could be infected. 



As it was not practicable to take cone-bearing trees of Tsuga 

 canadensis into the laboratory, branches with cones were placed 

 in water and a fresh surface was exposed to the water every day 

 or two by removing a small portion of the end of the twig. A 

 sowing was made on the cones and leaves on June 18 with abun- 

 dant pycnia on the cones and leaves on June 26. Aecia developed 

 abundantly on the leaves by July 8 and a few aecia appeared on 

 the cones a day or two later. Another sowing was made on June 

 22 with pycnia on the cones and leaves in abundance on July 2 

 and aecia on the leaves by July 8, also in abundance. Two or 

 three days later a few aecia appeared on the cones. 



About the same date, during a day or two of showery weather, 

 leaves of the Rhodora with germinating telia were collected in 

 the field and placed on the cones of a large tree of Tsuga cana- 

 densis. Some of the material was also thrown beneath and over 

 a small tree of the same species. Pycnia appeared abundantly 

 in about a week on the cones and leaves of both trees. There 

 was also a most luxuriant development of aecia on the leaves, but 

 only a few aecia matured on the cones. 



Dr. Spaulding generously furnished material from his collec- 



