420 BOTANICAL GAZETTE [NOVEMBER 
were kept under observation from early autumn until the general outbreak of 
rust the following spring. It was found also that young undeveloped sori in 
the leaves continued to develop when temperature conditions were favorable. 
The mycelium in the neighborhood of the sori was found to be alive. Uredo- 
spores of Puccinia dispersa retained their germinative power as zt as 100 
days, although the percentage of viable spores decreased during that time. 
The uredospores of a number of other rusts were found to be capable of ger- 
minating during the winter, but observations on these forms were not carried 
through the entire season. Uredospores of Puccinia simplex on Hordeum 
murinum germinated on December 29; those of Uromyces Anthyllidis on 
Anthyllis vulneraria on December 11; those of U. Ervi on Vicia hirsuta on 
January 29; and those of Puccinia toik on Lolium perenne on March 5. 
TAKMAN® has investigated for the conditions of Minnesota some of the 
problems relating to the specialization of physiological races of the cereal rusts 
and the resistance of different varieties of wheat to rusts. The results are in 
general in accord with the observations of other investigators, and serve to 
emphasize the fact that particular strains of Puccinia graminis inhabiting the: 
common cereals are more or less specifically adapted to particular species, but 
that this adaptation is not entirely rigid. Of all the forms, that on the oat is 
most strictly specialized. e forms on wheat, barley, and rye migrate more 
or less readily from one cereal to another. Treatment of the plants with anaes- 
thetics makes them more susceptible to infection. Resistance to rust seems to 
depend more on the nature of the variety than upon any external factors to 
which the plant is subjected. Certain phenomena, such as length of the incu- 
bation period of the rust within the plant, size of pustules and of spores, seem 
to be correlated with the degree of resistance of the host. The observations of 
MarsHALt Warp that in resistant plants the rust mycelium usually kil 
small infected areas of the leaves and thereby brought about its own destruc- 
tion was confirmed. 
iss SAHLI™ has continued the investigations begun by FiscHER’S on the 
susceptibility of hybrids and chimaeras of mixed immune and susceptible 
parentage to the attacks of fungi to which one parent is susceptible. A number 
of cultures with teleutospores of Gymnosporangium Sabinae, G. clavariaeforme, 
confusum, and G. et a Epa eGid species of Crataegus, Sorbus, 
and Mespilus, fthese plants. In general, 
there appears to be no constant relation between the state of immunity of the 
parents and that of the hybrids or chimaeras. For the details concerning each 
case, the paper itself should be consulted.—H. HAssELBRING. 
3 STAKMAN, E. C., A study in cereal rusts. Physiological races. Tech. Bull. 138. 
Agric. Exp. Sta. Univ. Minn. pp. 56. ls. 9. 1914. 
4 Sanit, GERTRUDE, Die Empfiinglichkeit von Rasggince’ Bastarden und Chi- 
miiren fiir Gymnosporangi en. Mycol. Centralbl. 3: 10-11. 1913 
1S Rev. Bot. GAz. §6:163. 1913. 
