junei5,i92o Relation of Rust in Seed Wheat to Seedling Infection 275 



(3) Infection undoubtedly spreads to the kernel from original infection 

 on the rachis, rachilla, or glumes. 



(4) The germinating power of the seed apparently is not impaired by 

 this rust infection. 



(5) When rusted kernels of wheat were sown in the field, no earlier or 

 more severe rust infection occurred on the resulting plants than on those 

 grown in adjacent plots which were sown either with clean seed or with 

 rust-infected seed which had been treated with the modified hot-water 

 treatment. 



(6) More than 2,500 plants were grown from rusted seed in a specially 

 constructed room in the pathological greenhouse at the University of 

 Wisconsin, and no rust infection appeared upon any of them at any 

 time. The conditions of growth of these plants were normal, and they 

 produced plump grain. 



(7) No spread of infection from the pericarp to the young plant was 

 found by examination histologically, although infected seed were germi- 

 nated under various conditions, simulating as nearly as possible natural 

 conditions in the field. 



(8) No infection appeared upon plants grown from seed which had 

 been covered with viable urediniospores of stemrust before sowing. 



(9) The results of the experimental work here reported indicate that 

 stemrust is not transmitted from one wheat crop to the next by means 

 of infected seed grain. Further, in the writer's judgment, the occur- 

 rence of stemrust sori in the pericarp of the caryopses of grains and 

 grasses has no especial significance, but the infection spreads to these 

 tissues just as it does from an infection point in any of the vegetative 

 parts of the plant. 



LITERATURE CITED 

 (i) BeauvERIE, Jean. 



1913. FREQUENCE DES GERMES DE ROUILLE DANS l'iNTiSriEUR DES SEMENCES 

 DE GRAMIN16ES. Compt. Rend. Acad. Sci. [Paris], t. 157, no. 18, p. 

 787-790. 



(2) 



I914. LES GERMES DE ROUILLES DANS l'iNT^RIEUR DES SEMENCES DE GRAM- 



in6es. In Rev. Gen. Bot., v. 25 (bis), p. 11-27, illus. 



(3) Blaringhem, T. 



I914. SUR la PROPAGATION DES ROUILLES DE C^R^ALES EN SUEDE ET EN 



FRANCE. Bul. Soc. Bot. France, t. 61, no. 1/3, p. 86-94. 



(4) BOLLEY, H. L. 



1898. EINIGE BEMERKUNGEN UBER DIE SYMBIOTISCHE MYKOPLASMATHEORIE 



BEi DEN GETREIDEROST. In Centbl. Bakt. [etc.], Abt. 2, Bd. 4, p. 

 887-896, I fig. 



(5) and Pritchard, F. J. 



1906. RUST PROBLEMS; FACTS, OBSERVATIONS AND THEORIES. POSSIBLE 



MEANS OF CONTROL. N. Dak. Agt. Exp. Sta. Bul. 68, p. 607-672, 30 



fig- 



(6) Carleton, M. a. 



1904. INVESTIGATIONS OP RUSTS. U. S. Dept. AgT. Bur. Plant Indus. Bul. 

 63, 32 p., 2 col. pi. 



