104 



PATHOLOGY 



[Box. Absts., Vol. X, 



1915 



1916 



1917 



Selected plants 



Check plants.. 



Difference. 



Selected plants 



Check plants.., 



Difference. 



Selected plants 



Check plants. . , 



Difference. 



Partially 

 infected 



1.66 

 0.00 

 1.66 



12.78 



1.44 



11.34 



23.66 



3.64 



20.02 



It is concluded that systematic selection increases resistance to stinking smut, even in very 

 susceptible varieties, and may prove valuable in practical application. — A. Bonazzi. 



662. Parde, M. Communications. Bull. Soc. Path. Veg. France 8: 14. 1921.— In a letter 

 to Et. Foex the writer states that Quercus cerris is very resistant to powdery mildew, Oidium, 

 which is so serious on most native species. — C. L. Shear. 



663. Pritchard, Fred J., and W. S. Porte. Relation of horse nettle (Solanum carolinense) 

 to leafspot of tomato (Septoria lycopersici). Jour. Agric. Res. 21: 501-505. PL 95-99. 1921. — 

 Experimental data are presented to establish the identity of a leafspot disease of nettle with 

 the leafspot disease of tomato. — D. Reddick, 



664. Smith, Erwin F. Effect of crowngall inoculations on Bryophyllum. Jour. Agric. 

 Res. 21: 593-597. PI. 101-110. 1921. — The effect of Bacterium tumefaciens on Bryophyllum 

 cahjcinum is like that on tobacco, geranium, etc. The paper controverts the report of M. 

 Levine (see Bot. Absts. 4, Entry 1315) that the shoots found in leafy crowngalls originate from 

 the tumor tissue, and that the organism has no stimulating effect on the formation of shoots, 

 but rather an inhibiting effect. — D. Reddick. 



665. Weis, F., og K. A. Bondorfp. Kemisk-biologisk undersofelse af skovjord under 

 overernaerede graner i lyngby skov. [Investigations relative to the cause of the hypertrophy of 

 Picea.] Forst. Forsogsv. Danmark 5: 343-352, 1921. — These researches, which are the 

 continuation of previous work, deal with the cause of hypertrophy observed on Picea excel sa. 

 Chemical analyses of the soil in which these plants were growing indicate a high nitrogen 

 content in proportion to mineral elements. The author believes that the cause of the hyper- 

 trophy will be found to lie in this unbalanced condition of soil elements. It is found that the 

 nitrogen in these soils, which are for the most part very acid, is quickly changed under favor- 

 able conditions to the nitric form. This change seems to be due to microorganisms since it 

 does not occur in sterile soil. None of the common nitrifying bacteria have been isolated, 

 but it is possible that in the forest soils, rich in humus and having a high acid content, other 

 organisms may be instrumental in bringing about nitrification. [Abstract through Kohler, 

 Rev. G6n. Bot. 33: 397. 1921.]— C. W. Bennett. 



666. Weiss, Freeman, and R. B. Harvey. Catalase, hydrogen-ion concentration and 

 growth of the potato wart disease. Jour. Agric. Res. 21: 589-592. 1921. — The overgrowths 

 of Solanum tuberosum caused by Chrysophlyctis endobiotica were compared with healthy tissue. 

 The hydrogen-ion concentration of the overgrowths is represented by Ph6 and of the healthy 

 tissue by Ph6.49. — Catalase activity is much greater in the overgrowth tissue, the values 

 being represented by 17.9 cc. of O2 for diseased tissue and 7.8 cc. for healthy tissue. Catalase 



