170 BOTANICAL GAZETTE [SEPTEMBER 
rye with aecidiospores from barberry leaves. SCHOLER’s publica- 
tion, however, remained buried until brought to light by NIELson. 
Infection of the barberry with P. graminis was not accomplished 
until 1865, when DE Bary (3) readily infected the young leaves 
with germinating sporidia, thus establishing the heteroecism of 
the organism. Unfortunately he was unable at the same time to 
germinate the mature aecidiospores, either fresh or after various 
periods of preservation, and hence the cereal host species was not 
reinfected, although the following year he accomplished this upon 
young rye plants. 
The distance rust is spread from the barberry is variously 
estimated by different writers. MARSHALL (24),? who set large 
barberry bushes in the grain fields and made careful observations, 
states that the rust extended 10 yards in the direction of the pre- 
vailing wind. SCHOLER (29), on the other hand, used small bushes 
and found that it scattered over an area of 30 to 40 square feet. 
Much greater distances are frequently recorded in the literature, 
although usually based upon casual observation or opinion. WITH- 
ERING (33),° for instance, advises that no barberry bushes should 
be planted within 300-400 yards of a grain field. 
The absence of the barberry and Mahonia in several regions 
where Puccinia graminis is prevalent, as cited for Ecuador by 
LAGERHEIM (21), seems to indicate that the heteroecism of the 
fungus is merely facultative. According to Barctay (1), P.- 
graminis is also commonly present in Jeypore, India, while the 
nearest barberry bushes are nearly 300 English miles distant. 
Moreover, ‘‘the aecidia are formed in summer, while the wheat 
and barley are grown in winter and harvested in April or May.” 
In this same category ZUKAL (34) places Bosnia and Herzegovina, 
where, according to Branpis (34), the aecidial hosts, if present 
at all, are very rare. Perhaps the most striking case of this kind 
is in Australia, where P. graminis causes enormous damage to 
wheat, yet the barberry is not present and the aecidial stage has 
never been found. 
The existence of a perennial mycelium, although established for a 
2 Cited by Artuur, Bull. Torr. Bot. Club 31:113. 1904. 
3 Cited by Ertxsson and HENNING (16). 
