tort} PRITCHARD—DISSEMINATION OF PUCCINIA r7t 
number of rusts, has never been proved for P. graminis. Erixs- 
SON (13, 14, 16) found the mycelium scarcely extending beyond the 
contour of the pustules. Dr Bary held that the development of 
the rust begins anew each year by the “germination of the teleu- 
tospores alone.” : 
P. graminis was formerly considered one species capable of 
infecting various members of the Gramineae, and this supposedly 
wide range of infecting power was thought to conduce to its spread. 
Errksson (16), however, after extensive inoculation experiments 
in Sweden, divides it into the following biological forms, which he 
finally classes as species: 
Puccinia graminis secalis (Secale cereale, Hordeum vulgare, and Triticum 
repens). ; 
Puccinia graminis avenae (Avena sativa). 
Puccinia graminis tritici (Triticum vulgare). 
Puccinia graminis airae (Aira caespitosa). 
Puccinia graminis poae (Poa compressa). 
Puccinia phlei-pratensis (Phleum pratense). 
CARLETON’S (10) experiments in America, however, do not 
support Eriksson and HENNING’s results. He finds no dis- 
tinction between the forms on wheat and barley. His results 
appear to establish two things: (1) “that the forms of black stem 
rust on wheat and barley, Hordeum jubatum, Agropyron tenerum, 
A. Richardsoni, and Elymus canadensis glaucifolius, are identical, 
with the probability that those on Elymus virginicus muticus and 
Holcus lanatus should be included; (2) that the black stem rust 
of Agropyron occidentale is physiologically distinct from any other.”’ 
Direct inoculation of the gramineous host with the germinating 
teleutospores has received some attention, although not as much 
as it deserves. Foremost among these experiments are probably 
those of DE Bary, who showed that the germinating sporidia 
of P. graminis would not infect the leaves of Triticum vulgare, T. 
repens, and Avena fatua. THUMEN (31), however, asserts that the 
sporidia of Melamspora salicina infect the willow quite as easily 
as do the uredospores. PLowricut (27) also, in a detailed report, 
claims to have infected wheat plants directly with sporidia (teleuto- 
bearing straw), although he afterward informed KLEBAHN that 
