DISEASES OP PLANTS. 449 



removed and the seed planted in the second layer prepared as usual. On a 

 third the soil was completely turned upside down three layers deep and the 

 potatoes planted as usual. The total yields in the three cases were, respec- 

 tively, 65, 205, and 255 lbs. per square rod, with an infection rate, respectively, 

 of 53. 41, and 19.5 per cent of the tubers produced. 



Report on the prevalence of wart disease in Shropshire, 1912, J. W. 

 Rylance (Field Expts. Harper-Adams Agr. Col., and Staffordshire and Shrop- 

 shire, Rpt. 1912, pp. 30, 31). — The author reports the results of inspection of 

 about 1,000 gardens and fields of potatoes. The disease was discovered in 535 

 places. In a number of cases the seed had been purchased from peddlers or at 

 auction or from other unreliable sources. It was shown in some instances that 

 the spores had lain in the ground quiescent while nonsusceptible crops were 

 grown during 4 to S years, the seed and manure being above suspicion, but that 

 on again planting these plats in potatoes from § to f of the crop was affected 

 with wart disease. 



Some successful inoculations with the peach crown g'all org'anism and 

 certain observations upon retarded gall formation, C. O. Smith {Phyto- 

 pathology, 3 (1913), No. 1, pp. 59, CO). — The author reports successful inocula- 

 tions with the crown gall organism (Bacterium tumcfdciens) from peaches on 

 pepper trees, Japanese persimmons, various walnuts, pecans, the forest red gum, 

 a large number of varieties of quince, almond, apricot, cherry, peach, and plum, 

 oranges, lemons, sweet limes, fig, the Victoria bottle tree, and the flame tree. 



Attention is called to two instances of retarded gall formation, in the Anglers 

 quince and the fig. 



The migration of Bacillus amylovorus in the host tissues, Feeda M. Bach- 

 MANN (Phytopathology, 3 (1913), No. 1, pp. 3-lJt, pis. 2, figs. 2). — An examina- 

 tion has been made into the histological relations of host and parasite in con- 

 nection with B. amylovorus. Inoculations were made of pear blossoms, water 

 shoots of apple, young pear seedlings, young shoots of pear and plum, and 

 fruits of the apple and pear. 



In the shoots of the different hosts the first indication of disease is shown 

 by the plasmolysis of the cells of the cortex and to some extent those of the 

 pith. In the early stages of infection in apple shoots the intercellular spaces 

 were found crowded with bacteria, while the cells were only partially plasmolyzed. 

 Later the walls of the cells of cortex and pith become broken down and bacteria 

 may enter the cells. The bacteria were found to enter the xylem tubes very 

 readily, and it is thought that in tender tissues of young seedlings the organisms 

 may penetrate the xylem tubes at any place. The parenchyma cells between 

 the xylem tubes are densely filled with granular cytoplasm and are usually 

 entirely free from bacteria. It is thought that probably the bacteria destroy or 

 breali through the thinner walls of the tracheids, and that the thin-walled cells 

 of the xylem become plasmolyzed and partially disintegrated,, resulting in large 

 open spaces being formed in the xylem. 



In the fruit the author found that the path of migration was through the 

 intercellular spaces from the region of inoculation to all parts of the fruit. 

 The bacteria were found to extract the cell sap from the cells causing their 

 death. It is believed that if toxic substances are produced they do not precede 

 the advance of the bacteria, since bacteria are found between apparently normal 

 cells. There was no evidence that the bacteria progressed from cell to cell. 



Combating' Peronospora on the basis of recent investigations, R. Geeneck 

 (Wclnbau u. Weinhandel, SO (1912), No. 47, p. 498).— In 1912 experiments were 

 carried out utilizing the results of studies on Peronospora of grape obtained by 

 H. Miiller-Thurgau (E. S. R., 2S, p. 244). Of the four plats studied, one was not 



