234 
Mycologia 
periments were performed. They were selected from a place re- 
mote from any known or suspected source of infection and in all 
cases, as described in the experiments, a number of checks were 
kept. The writer was thoroughly familiar with the locality, and 
no fern rust appeared until some weeks after the ferns were 
obtained, nor did any appear later on the plants surrounding 
those that had been selected for the experiments. 
The aeciosporic material was all collected near Pictou. At 
the time of collection no uredinia had developed on the ferns 
near the trees from which it was collected or anywhere in the 
vicinity. 
The ferns used in the experiments with the aeciosporic mate- 
rial were sprayed with water by means of an atomizer. The 
aeciospores were then shaken from the shoots on the under side 
of the leaves of the ferns. The shoots bearing aecia were also 
‘suspended above the ferns, and the whole was covered with a 
belljar for a day or two. This was done in a room separate 
from where the cultures and checks were kept. 
The writer is indebted to Mr. E. M. Duporte and Mr. P. I. 
Bryce, assistants in the department, for the care of the cultures at 
Macdonald College during his absence, also to the Commissioners 
and Dr. R. Maclellan, of Pictou Academy, who in their generous 
way freely placed the laboratories of that institution at his 
disposal. 
Uredinopsis Struthiopteridts Stormer 
Teliosporic material of this rust on Onoclea Struthiopteris (L.) 
Hoffm. was suspended above a small plant of Abies balsamea 
(L.) Mill, on May 13. Pycnia were noticed on May 27 which 
probably appeared earlier, and aecia began to appear on June i, 
both in great abundance, practically every leaf of the young 
shoots being infected. Another sowing in a similar manner on 
May 28 gave pycnia on June 9, with aecia showing by June 18. 
Fresh aeciospores of Peridermium balsameum on Abies bal- 
samea (L.) Mill., which were collected beside ferns of Onoclea 
Struthiopteris that were badly rusted the previous season, were 
sown on Onoclea Struthiopteris, O. sensibilis L., Phegopteris 
Dryoptcris (L.) Fee and Osmunda Claytoniana L. on June 27. 
