Fraser: Uredinopsis mirabilis 
27 
teliosporic material on a flourishing young tree of the same species 
in the laboratory also failed. 
From field observations and culture experiments described in 
this and previous papers, the writer concludes that the Melani - 
psora on Populus grandidentata in eastern Canada has its aecia 
on the leaves, young twigs and cones of Tsuga canadensis and 
does not infect Lari. x laricina . 2 It may be that the rust on 
Populus grandidentata is a distinct species as Arthur 3 has shown 
that Melampsora Medusae on P. deltoides and P. tremuloides has 
aecia on Larix, but for the present it seems best to regard it as a 
specialized form of Melampsora Medusae. Attempts to infect 
Populus deltoides with the aeciospores obtained from the cul- 
ture failed. 
Pucci niastrum Myrtilli (Schum.) Arth. 
Teliosporic material of this rust on Gaylussacia resinosa (Ait.) 
T. & G., collected at Isle Perrot, P. Q., was sown on Tsuga cana- 
densis on May 28th. Pycnia were present on June 9th and aecia 
on June 16th, both in abundance. 4 
Calyptospora columnaris (Alb. & Schw.) Kuhn 
Germinating teliosporic material of this rust on Vaccinium 
pennsylvanicum Lam., collected at Pictou, N. S., was sown on 
Abies balsarnca on May 15th. Aecia were noticed on June 3d 
and were mature by June 12th. No pycnia were formed. 5 
Peridermium Harknessii Moore 
Attempts were made with the aeciospores of this form collected 
at Vernon, B. C., to infect Commandra umbellata (L.) Nutt., but 
without success. It was doubtful, however, if the aeciospores 
were in good condition when sown. 
Summary of Cultures Described in This Article 
Uredinopsis mirabilis Magn. Five successful sowings of telio- 
spores from Onoclea sensibilis L. on Abies balsarnca (L.) Mill. 
2 See Mycol. 3 : 188. 1912 ; 5 : 238. 1913. 
3 Jour. Myc. 10: 13. 1904; u : 52. 1905; 12: 13. 1906. 
■*See Mycol. 5: 237. 1913. 
3 See Mycol. 4: 177. 1912. 
