770 EXPERIMENT STATION RECORD. 



radicicola and also Tylemhus sp., an internal browning and gelatinization of the fruit 

 probably due to the root disease, and a leaf disease which is acconii)anied by a spe- 

 cific fungus. These diseases will be subjects of further investigation and report. 

 Preliminary investigations have also been begun on diseases of coffee and sugar cane. 



Tlie origin and propagation of cereal rusts througli tlie seed, J. Eriksson 

 {Ann. Sci. Nat. Bot., S. ser., 15 (1902), pp. 1-160, ph. 5, fig». 10; ahx. in Bot. Cenihl., 

 90 {1902), No. 6, pp. 14-6-150). — In continuation of his investigations on the cereal 

 rust problem (E. S. R., 11, ]>. 949), the author gives the results of experimental 

 studies in rust propagation. In the previous paper he advanced the hypothesis of 

 the p()ssibility of infection through the seed, or the mycoplasma theory as it is 

 called, and in the present account examples are given which are held to substantiate 

 that claim. Methods were devised by which cereals were grown to maturity under 

 what appears to have been perfect isolation. In numerous instances the plants were 

 infected with rust even after all precautions had been taken to prevent external 

 infection. In the second part of his paper the methods of propagation of rusts are 

 discussed. It is claimed that cereal rusts can not be propagated either by an inter- 

 cellular mycelium, as the presence of such a means has not been shown for most 

 species of cereals, or l)y groups of spores on the surface or in . the interior of the 

 grain. It is further claimed that the uredo and teleutospores are not sufficiently 

 abundant to habitually cause infection. Having disposed of these methods of infec- 

 tion the author claims the di.sease is to a large degree caused by the mycoplasma 

 which exists in a symbiotic stage in the grain. Thus far it has been impossible to 

 demonstrate the presence of .this source of infection in its primary state, but it is 

 believed that an intermediate form has been found which connects the invisible 

 plasma and the mycelium of the rust. These are certain minute corpuscular bodies 

 which float about in the protoplasm of the c-ell and later give rise to mj^celium. The 

 varying susceptibility of different varieties is held to be an argument in favor of the 

 author's theory of rust propagation. 



The nature of the infection is said to preclude the use of parasitic or fungicidal 

 agencies for the prevention of rust. The treatment recommended is preventive, and 

 the author advises the use of resistant varieties and the a])andonment of the cultiva- 

 tion of all varieties which are notably subject to rust. He believes concerted studies 

 should be made in all countries w' here cereals are injuriously affected by rusts, so 

 that the effect of soils, exposure, fertilizers, etc., on rust may be ascertained, and 

 attempts made to breed more resistant strains and varieties. 



The recent literature relating to rusts is reviewed and a bibliography of the sub- 

 ject is ap])ended. 



The occurrence and distribution of cereal rusts through the seed, J. Eriks- 

 son {Medd. K. Landth. Akad. Exptlfult., No. 72, pp. 51, pis. 3, Jigs. lO').— This is a dis- 

 cussion of the mycoplasma theory relating to the origin and distribution of cereal, 

 rusts. The author recf)gnizes the following species of Puccinia: P. grmninis, the 

 black rust, the a^cidium of which occurs upon the barberry, with 6 specialized forms; 

 P. phlei-pratensis, the timothy rust; P. glumarum, the yellow rust, with 5 specialized 

 forms; P. dispersa, the brown rust of rye, the ajcidium of which occurs on certain 

 boraginaceous plants; P. triticina, the brown rust of wheat; P. hromina; P. agropij- 

 rina; P. holcina; P. triseti; P. simplex; P. coronifera, the crown rust, w'ith 6 special- 

 ized forms, the a^cidium of which occurs on species of Rhamnus; P. coronata, with 5 

 specialized forms; and an unnamed species of which 2 forms are recognized.— f. \v. 



WOLL. 



On the specialization of cereal rusts, J. Eriksson {Medd. K. Landth. AJcad. 

 Exptlfult., No. 73, pp. 25). — The results of the author's investigations on the special- 

 ization of cereal rusts to certain definite hosts are shown. The author considers 

 specialization as an expression of inherent tendencies on the part of the rust toward 

 producing new forms. This tendency is guided by the vegetative and climatic condi- 



