REED: SPECIALIZATION OF PARASITIC FUNGI 397 
their capacity for infection in the same way as uredospores from the 
same gramineous hosts used as a source of the teleutospores for in- 
fecting the barberry. The only marked variation from this is in the 
case of aecidiospores from the barberry produced by inoculation with 
teleutospores from Bromus madritensis, Briza maxima, Festuca myurus, 
and Phalaris canariensis, all hosts for the race Avenae, which infected 
not only Avena sativa but also Secale cereale, a host of race Secalis of 
the rust. 
Jaczewski (68) found close correspondence in the infecting capacity 
of aecidiospores from the barberry arising from teleutospore inocu- 
lations from definite plants and that of the uredospores from the same 
gramineous hosts. In fact his establishment of the nine specialized 
races of the black stem rust in Russia is based as much on aecidiospore 
inoculations as on uredospore inoculations. 
Stakman (143) also found no essential differences in the infecting 
capacity of uredospores from wheat and Agropyron repens and that of 
aecidiospores from the barberry arising as a result of inoculation with 
teleutospores from these same hosts. Pritchard (110) also found a 
correspondence between the infecting capacity of uredospores and 
aecidiospores. 
Bolley and Pritchard (20) assert that aecidiospores from a single 
barberry hedge have been used to infect wheat, oats, barley, Hordeum 
jubatum, Agropyron tenerum and A. repens. ‘The origin of the infec- 
tion of the barberry was not known but probably was due to teleuto- 
spores from Hordeum jubatum. In 1905 aecidiospores from barberry 
readily infected barley and Hordeum jubatum, less readily wheat, and 
oats hardly at all. 
Arthur (10), however, has come to the conclusion that the “bar- 
berry acts as a bridging host between each and every other gramineous 
host.’’ The evidence that he gives in support of his statement may 
be indicated: (1) aecidiospores from barberry, produced by inocula- 
tion with teleutospores from Agrostis alba, infected wheat and barley, 
but not oats; (2) aecidiospores from barberry produced by inocula- 
tion with teleutospores from Agropyron tenerum, infected oats; (3) 
aecidiospores from the barberry, produced by inoculation with teleuto- 
spores from Sitanion longifolium, infected wheat; (4) aecidiospores 
from the barberry, produced by inoculation with teleutospores from 
Elymus canadensis, failed to infect wheat and rye. No one has 
recorded any data on the infecting capacity of uredospores developed 
on Sitanion longifolium; accordingly we have no information whether 
this rust is a distinct race or whether S. longifolium is merely a host 
for specialized race Tritici. Further, Agropyron tenerum is a host for 
specialized race Avenae; hence the results recorded are just what one 
27 
