188 



Mycologia 



27. Pycnia appeared on June 2 followed by aecia in a few days. 

 Another sowing was made on two trees of the same host on May 

 30, with pycnia by June 3 and aecia by June 10. Two different 

 sowings were made on Larix laricina (DuRoi) Koch but no in- 

 fection followed. The willow from which the teliosporic mate- 

 rial used in the experiments was obtained was determined as 

 Salix discolor Muhl. by John Macoun. Collections were also 

 made on Saliv rostrafa Richards. 



The Caeoma was not so common in the summer of 191 1 as in 

 the previous season, probably owing to the dry weather, but the 

 collections made were in the vicinity of willows that were infected 

 with this rust the preceding year. It does not seem to have been 

 previously collected. The pycnia are numerous, hypophyllous ; 

 the aecia hypophyllous, rather large and conspicuous; the aecio- 

 spores ovoid or globose, 13-16 X 15-24 /a; wall rather thick, 

 2-3 /X, finely verrucose ; contents orange. 



Melampsora (Medusae Thiim.?) 



During the summer of 19 10 several small hemlocks in the nat- 

 ural park at Truro, N. S., were observed to be so severely in- 

 fected by Caeoma Abietis-canadensis Farl. that it suggested local 

 infection. In the fall of the same year, the writer, in company 

 with Professor H. W. Smith, of the Truro Agricultural College, 

 visited the place and careful search was made for some clue to the 

 telial stage. No rust was found in the vicinity, except a Melamp- 

 sora on Po pubis grandidentata Michx., several trees of which grew 

 near. This was regarded as Melampsora Medusae Thiim. and 

 examination seemed to confirm this view. As the aecial stage 

 of this rust has been shown to occur on Larix, the proximity of 

 the poplar rust was thought to be of little significance. 



Teliosporic material on Populus grandidentata, however, was 

 collected near Pictou in the spring, and on June 9 sowings were 

 made on Larix laricina and Tsuga canadensis. A few pycnia ap- 

 peared on the Larix on June 25 but there was no further develop- 

 ment, although the plants remained in good condition. Pycnia 

 appeared on Tsuga canadensis on June 16 and aecia of the 

 Caeoma type on June 25. Another sowing on Tsuga canadensis 

 on June 19 gave pycnia on June 27 and aecia on July 4, and a 



