100 Wisconsin Academy of Sciences, Arts, and Letters. 
uredospores of P. graminis Pers., were found on Aira caespitosa 
on April 1st, 1892, and of P. Plilei-pratensis Erik, and Henn. 
December 29th, 1891, and again on. March 28th, 1892. In ex¬ 
perimenting with P. glumarum (Schm) Erik, and Henn., cer¬ 
tain leaves were marked in the fall of 1892 and the amount of 
infection noted. After a very severe winter the leaves were 
again examined April 27th, 1893, and three of ninety which 
were marked were found to bear open pustules. P. coronata 
Corda was also found in late fall and early spring. Viable 
uredospores of this rust were found on Melica nutans, Novem¬ 
ber 31st, 1891, and in the same place April 5th, 1892. Besides 
the above records, the abundance of uredospores of P. glumarum 
on February 5th, 1894, is incidentally mentioned. They also 
noted that a general outbreak of uredospores of the same rust 
occurred on wheat within a week after the snow disappeared in 
the spring of 1892. 
In spite of these facts, it is Eriksson’s conclusion that, in a 
climate like that of Sweden, the rusts do not winter to any ap¬ 
preciable extent either as uredospores or as a mycelium within 
the host plant. His statements to this effect are most positive 
except in the case of P. glumarum. Even in the case of that 
rust, he does not believe that the number of uredospores appear¬ 
ing at the close of winter ^ three rusted leaves in ninety as 
shown by his experiments) would be sufficient to insure the con¬ 
tinuation of the fungus. He holds for the wintering of rust, 
as for its propagation through seed, to his well known myco- 
plasm hypothesis. The evidence for the actual existence of 
this non-filamentous mycoplasm imbedded in the protoplasm of 
the host cells as presented by Eriksson and Henning, and later 
by Eriksson and Tischler 1 seems entirely inconclusive. The 
structures described are doubtless artefacts or distorted ele¬ 
ments of the host cells themselves. The temperatures at Stock¬ 
holm for the winters of 1890 to 1894 are recorded and may be 
tabulated as follows for comparison with the temperatures at 
Madison, as given in a later table. 
i Eriksson and Tischler,—K. Svenska Vetenskaps Akademiens Hand- 
lingar. Bd. 37. No. 6, 1904. 
