122 
Journal of Agricultural Research 
Vol. XIV, No. * 
(7) Negative results were obtained in attempting to alter the infection 
capabilities of the rust by growing it for generation on susceptible F 3 
plants of the cross Marquis X Kubanka (Cl 2094). 
(8) F 9 hybrids of the cross Haynes Bluestem X Kubanka (Cl 2094) 
were apparently homozygous for morphological characters but heter¬ 
ozygous for the character of rust resistance. Susceptible hybrid plants 
did not act as bridges for the rust. 
(9) The facts recorded in this paper, supported by experimental 
work in the rust nursery and by field observations, indicate that rust 
resistance is comparable with other permanent characters, and that 
it is not primarily controlled by seasonal conditions, soil type, geographical 
location, or other cultural conditions. It is rather an hereditary char¬ 
acter, which can not be produced by the accumulation of fluctuating 
variations within a susceptible line, nor broken down by changes in the 
host or parasite. 
(10) The resistance of wheat varieties may vary in different regions 
because of the presence of different biologic forms of rust. 
(11) There seems to be little basis for the belief that hybrids between 
resistant and susceptible varieties will exert a harmful final effect by 
increasing the virulence and host range of stemrust. 
LITERATURE CITED 
(1) Bifren, R. H. 
1907. STUDIES IN THE INHERITANCE OR DISEASE-RESISTANCE. I. In Jour. 
Agr. Sci., v. 2, pt. 2, p. 109-128. 
(2) . 
1912. STUDIES IN THE INHERITANCE OR DISEASE-RESISTANCE. II. In JOUT. 
Agr, Sci., v. 4, pt. 4, p. 421-429. 
(3) Evans, I. B. P. 
1911. SOUTH AFRICAN CEREAL RUSTS, WITH OBSERVATIONS ON THE PROBLEM 
op breeding rust-resistant wheats. In Jour. Agr. Sci., V. 4, 
pt. i, p. 95-104. Bibliography, p. 104. 
(4) Freeman, E. M. 
1902. EXPERIMENTS ON THE BROWN RUST OR BROMES (PUCCINIA DISPERSA). 
In Ann. Bot., v. 16, no. 63, p. 487-494. 
(5) - and Johnson, E. C. 
1911. the rusts or grains in the united states. U. S, Dept. Agr. Bur. 
> Plant Indus. Bui. 216, 87 p., 2 fig., 1 pi. Bibliography, p. 79-82. 
(6) Johnson, E. C. 
1911. timothy rust in the united states. U. S. Dept. Agr. Bur. Plant 
Indus. Bui. 224, 20 p. 
(7) Salmon, E. S. 
1904. ON ERYSIPHE GRAMINIS DC., AND ITS ADAPTIVE PARASITISM WITHIN THE 
genus bromus. In Ann. Mycol., Jahrg. 2, No. 3, p. 255-267, 8 diagr.; 
No. 4, p. 307-343. Bibliography, p. 266-267. 
(8) Stakman, E. C. 
1914. A STUDY IN CEREAL rusts: physiological races. Minn. Agr. Exp. 
Sta. Bui. 138, 56 p., 9 pi. Bibliography, p. 50-54. 
