172 BOTANICAL GAZETTE [SEPTEMBER 
“his work rested upon an error.’’ Other failures to infect wheat 
with germinating sporidia are reported by WARD (32) and Errks- 
SON (15), though no mention is made of the number of trials nor 
the point of inoculation. Notwithstanding these failures, BRE- 
FELD (8) thinks further attempts should be made to infect young 
cereals with germinating teleutospores. His discovery that only 
the youngest tissues of cereals are penetrated by smut sporelings 
gives encouragement for numerous experiments in this direction. 
The hardened tissues may offer too much resistance to the delicate 
germ tubes of the sporidia, he says, which bore directly through 
the epidermis instead of entering through the stomata, as do the 
germinating uredospores and aecidiospores. 
The behavior of the germinating teleutospores is influenced 
somewhat by their environment. MacGnus (23) found that teleu- 
tospores of P. graminis kept under a thin layer of water formed a 
germ tube instead of a promycelium. These results were after- 
ward confirmed by BLACKMAN (5), who also included two other 
genera. Other factors are sometimes operative, as KIENITZ- 
GeRLorr (18) reports that thin-walled teleutospores of Gymno- 
sporangium clavariaeforme also form a germ tube. When teleu- 
tospores germinate in air, however, they almost invariably form 
sporidia. This is true of P. graminis even in Australia, where it 
has no aecidial host species. 
The uredospores of P. graminis soon lose their viability, accord- 
ing to De Bary (3), in one to two months if kept dry. BOLLEY 
(6, '7), however, obtained a germination of 5 per cent after exposing 
them to air and sunlight during the month of August, and even 
claims they may live over winter. Christman (11) failed to ger- 
minate them after November 23, although the uredospores of P. 
coronata were viable the 26th of January, and those of P. rubigo- 
vera the 21st of March. Perhaps the most extensive experiments 
of this kind have been made by Eriksson and HENNING (16), 
whose results show that the uredospores of both P. graminis and 
P. glumarum are unable to survive the winter in Sweden. The 
absence of fresh uredo pustules during two or three months in the 
spring is cited as additional proof, since the period of incubation 
after inoculation with uredospores is only about ten days. The 
