100 
IOWA ACADEMY OF SCIENCES 
7-9", colorless. Magnus^ lias given an excellent account of the develop- 
ment of Melampsorella. He thinks the teieutospores develop immedi- 
ately after the appearance of the uredo spores and that the ocurrence 
of the uredo spores in the spring simply indicates the further develop- 
ment of H.e fungus. The fungus is carried over from one season to the 
other by the mycelium which vegetates in the cortex and parenchyma of 
the stem. The teieutospores sometimes seem to divide longitudinally, 
but usually they develop crosswise, and as many as 2-4 cells may occur 
in a single epidermal cell. The germination of the teieutospores is inter- 
estki^g. In that process the promycelium is bent at right angles to the 
epidermal cell and divides into four cells, in the convex side there devel- 
opes a small sterigma that produces frorn its apex a single sporidium. 
Geogkaphical Distetbution. The wide distribution of this species in 
Europe has been known for some time. It is referred to by Plowright- 
as occurring in England on Picea excelsa, by LaSalle in Italy, and 
Tubeuf, Frank, Hartig, and DeBary and other writers mention its common 
occurrence. 
It is found in Germany, Switzerland, Australia and Siberia. In North 
America it was first found by Sprague in New Hampshire in 1856 accord- 
ing to Dr. Farlcw'\ and by T. P. James about the same time in the White 
Mountains. Dr. Farlow further states that Professor Macoun has col- 
lected it at Gaspe, Canada, and Prof. Brainerd at Ripton, Vermont. 
Anderson* reports it from Leech Lake, Minnesota; Prof. Peck from sev- 
eral localities in New York. It was common at the following points in the 
Uintah Mountains: East Provo Canon, Weber Canon. Bear river. Black’s 
Fork, and Ashley creek, all occurring on AMes sicdalpina at an altitude 
varying between 8,500 — 10,000 feet, being in fact coexistent in its distribu- 
tion with the Rocky Mountain balsam. Prof. Nelson* reports it on Picea 
engelmani, Battle Lake, Carbon Co., Wyoming. The host is most likely 
wrong. Miss Paddock and Ferd. Reppext report it common in the Big 
Horn Forest Reserve. 
Economic Considerations. This is a most destructive parasite being 
much more abundant than any other species of the genus. The distor- 
tions it causes are often quite large. The fungus appears on both young 
and old trees and frequently on the terminal shoot which soon destroys 
the tree. Its mycelium is perennial and may therefore continue to produce 
spores for years, the broom in the meanwhile enlarging. As a result of 
the attack of this parasite, fissures arise in the bark which cause drying 
out and cracking and may lead to the attacks of other wood parasites. 
The only means of checking the growth of the fungus is to cut the tree 
below the affected branches. The v/ood of diseased trees is extremely 
brittle and where such is used the lumber is of very poor quality. 
Peridermium^ aMetinum (Alb. & Schw.) 
1. Ber. Dent. Bot. Gesell. 17: 337. PI. 26. 
2. British Ured. & Ust. 270. 
2. Zeitsch. f. Pflanzenk. 1 : 223. 
.3, Appalachia. 3 : 243. • , t • • ' ■ ■ . 
4. Bot. Gazette. 24: 33 0. 
5. Crypt, of Wy. Kept. Agrl. Coll. & Wy. Agrl. Exp. Sta. 10: 30. No. 
4244. 
