156 Contribution to Knowledge of Silver-Leaf Disease 



epidermal cells. I succeeded in staining them by the method of 

 E. F. Smith (16, in. pp. 129, 914). These bacteria may here be of a 

 secondary nature; nevertheless their appearance is a promising subject 

 for further study 1 . I hope to continue along this line later but for the 

 time being I am not able to extend the work. 



The question of the Silver-leaf disease is of economic importance 

 especially in England, as the losses caused by it reach a considerable 

 amount. It is not so in Bohemia, where this disease appears frequently, 

 but its virulence is not yet so marked. 



The investigation here recorded was carried out at the suggestion 

 and under the direction of Professor V. H. Blackman, and I wish to 

 acknowledge my indebtedness to him for his valuable suggestions and 

 for the interest with which he followed my work. I desire also to 

 thank Mr W. Brown, M.A., of the Imperial College of Science and 

 Technology, London, and Dr Arthur H. Graves of New Haven, Conn. 

 U.S.A., for kindly editing the English text. 



LITERATURE. 



(1) Brooks, F. T. Silver-leaf disease (II). Jotirn. of Agric. Sci., 1913, vol. v. 



(2) Delacroix, G. Maladies des plantes cultivees (non-parasitaires). 1908. 



(3) Giissow, H. T. Der Milchglanz der Obstbaume. Zeitschr. fur Pflanzenkr., 



1912. 



(4) Guttenberg, H. Cytologische Studien an Synchytrium-Gallon. Johrb. f. 



wiss. Bot., 1909. 



(5) Klemm, P. Desorganisationserschcinungen der Zelle. Johrb. f.vnss. Bot., 1895. 

 ((>) Kusano, S. On the Life History and Cytology of a new Olpidium with 



special reference to the Copulation of motile Isoganietes. Joum. of the 

 Coll. of Agric, Tokyo, 1912, vol. iv. 



(7) KtfsTER, E. Die Gallen der Pflanzen. Leipzig, 1911. 



(8) Kuster, E. Aufgaben unci Ergcbnisse der entwicklungsmechanischen 



Pflanzenanatomie. Progr. Ret. Bot., 1908. 



(9) Massee, G. Diseases of cultivated plants and trees. London, 1910. 



(10) Nemec, B. Uebcr die Einwirkung des Chloralhydrats auf die Kern- und 



Zellteilung. Johrb. f. wiss. Bot., 1904. 



(11) Nemec, B. Das Problem der Befruchtungsvorgange und andere cytologische 



Fragen. Berlin, 1910. 



(12) Percival, J. Silver-Leaf disease. Joum. of Linnean Society, vol. xxxv, 1902. 



1 I regret that the work of ISlackmore (quoted in the work of < Jiissow) is not accessible 

 to me. This author is of the opinion that bacteria are the cause of (his disease. 



