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   OBSERVATIONS ON THE WINTERING OF GRAIN
                            RUSTS.
                       A. H. CHRISTMAN
   The manner in which grain rusts pass the winter in northern
 climates and in regions where the barberry is wanting, is still
 considered an open question. Eriksson and Henning (1), while
 they record the germination of uredospores collected during the
 winter and early spring, conclude that these spores and the
 mycelia producing them play no important part in perpetuat-
 ing the fungus. As is well known, they hold that rust may be
 transmitted as a nonhyphal, so called, mycoplasm in the cells
 of the host. It is quite possible that their adherence to the my-
 coplasm hypothesis on other grounds has biased their judgment
 on the question of the ability of uredospores and mycelium to
 pass the winter. Ward (2) rcjects the mycoplasm hypothesis
 entirely and probably most gyologists regard it with great
 skepticism.
 On account of the position taken by Eriksson and Henning,
 it may be well to review some of the earlier observations re-
 corded as bearing osn this question. As early as 1875 Kuhn (3)
 found uredospores of P. graninis Pers. in the early spring near
 Halle, in Germany, and in same year Nielson4 concluded that
 in Denmark, P. rubigo-vera 1). C., passes the winter as a myce-
 1Ericksson and Henning,-Diie Getreideroste Stockholm, 1896.
 2Ward, H. M. On the Histol. of U. dbispersa, Erikss;., and the "My-
 coplasm" Hypothesis. Phil. Trans. Roy. Soc., Vol. 196, p. 29, '03.
 3Uber die nothwendigkeit eines Verbotes der Pflanzung und Anlage
 der Berberitzenstrauches. Kuhn J. Landw. Jahrb. Bd. 4, 1875, p. 399.
 4 P. Nielsen,-De for Landbruget farligeste Rustarter og Midlerne
mod dem. Ib., 1875, Bd. 1.
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