Pflanzenkrankheiten. — Bacteriologie. 271 



Pethybridge, G. H., In vestigations on Potato Diseases. 

 (Fifth Report). (Journ. Dep. Agric. and Tech. Instruc. Ireland. 

 XIV. p. 433-455. 1914.) 



The author puts on record the results of further work chiefly 

 in connection with the diseases Phytophthova infestans. De By., 

 Sclerotinia sclerotiorum.^ Mass., Spongospora subterranea, Johnson, 

 Bacillus ntelanogenes, P. and M. and Phytophthora erythroseptica, 

 Pethyb. 



In the case of Phytophthora infestans, experiments were conti- 

 nued on spraying, the best time, the strength of the mixtures used, 

 the method of application, etc. Particular attention was devoted to 

 testing the efficacy of various proprietary powders, as compared 

 with the ordinary Bordeaux and Burgundy spraying mixtures. The 

 results indicated that any advantages in handling possessed by 

 powders are more than outweighed by their greater cost and dimi- 

 nished efficiency. 



With regard to the other diseases, previously recorded results 

 were confirmed. In the case of Spongospora a Single experiment 

 was made of treating the soil with a mixture of sulphate of ammo- 

 nia and lime, with slightly favourable results. 



E. M. Wakefield (Kew). 



Pethybridge, G. H., The Spread of the Celery Leaf-Spot 

 Disease by the use of affected seed and its prevention. 

 (Journ. Dep. Agric. and Tech. Instruct. Ireland. XIV. p. 687—694. 

 1914.) 



Of 109 samples of celery "seed'' examined, pycnidia of Sepioria 

 Petroselini var. Apü were found to be present in 100. VVhere these 

 contained living spores, a certain member of diseased seedlings 

 were obtained on germination of the second. In actual practice the 

 percentage of diseased plants would probably be greater, owing to 

 the seed being sown more thickly than was the case in these expe- 

 riments. Klebahn's copper sulphate method of treating the seed 

 was found to cause serious decline in the percentage of germination. 

 Hydrogen peroxide and formalin, however, while suppressing the 

 disease entirely, did not interfere with the germinating power of 

 the seeds. This result was obtained both when the seed was sown 

 immediately after treatment, and also when it had been thoroughly 

 air dried and stored for two months. E. M. Wakefield (Kew). 



Ambroz, A., Cytologische Beiträge zur Morfologie un d 

 Aetiologie von sog. Involutions- und Degenerations- 



formen bei Bakterien. (Casopis ceskych lekaruv. p. 1056. 1914. 

 Böhmisch.) 



Es ist bekannt, dass unter dem Einfluss verschiedener Mo- 

 mente, namentlich der Beschaffenheit des Nährbodens die sog. nor- 

 male Form des Bakterienkörpers sich mannigfaltig ändern kann, 

 und dass sämtliche diese sog. Involutionsformen für degenerative 

 Erscheinungen gehalten werden. Aber schon der Umstand, dass 

 manche im Maximum der Lebenstätigkeit erstreben spricht dafür, 

 dass sich nicht in jedem Falle um eine Degeneration handeln muss, 

 dass vielmehr — wenn man das konstante Auftreten einer bestimm- 

 ten Form bei bestimmten Veränderungen in Betracht zieht — um 



