WAKKRR'S HYACINTH GERM, 



Pseudovionas hyacinthi (Wakker). 



HISTORICAL. 



Dr. J. H. Wakker published five papers on the hyacinth germ 

 between 1883 and 1888. His studies attracted wide attention because 

 he was one of the earliest investigators in the field of plant bacteriol- 

 ogy in a time of general skepticism and uncertainty, and also because 

 of the great care with which he seemed to have worked out his results. 

 Since the conclusion of Dr. Wakker's studies, which were begun in 

 1880, no bacteriologist or plant pathologist seems to have given any 

 personal attention to the disease. Several pathologists have written 

 about it or referred to it,' but nothing of any value has been added, 

 and some of the comments have served only to throw doubt on the 

 original inquiry. 



In reading Dr. Wakker's papers for the purpose of making an 

 abstract, I was at once struck with the need of a reinvestigation of 

 the subject. This seemed necessary for two reasons: (1) Methods of 

 isolation were not then as well understood as at present, and most of 

 Wakker's successful infections seem to have been direct ones; (2) the 

 germ is so imperfectly described that, excluding the test of patho- 

 genesis, the identification of any particular organism as Bacterium 

 hyacinthi Wakker would be altogether impossible. No disparage- 

 ment of Dr. Wakker's beautiful studies is here intended. At the same 

 time nothing perhaps better serves to illustrate the important advances 



' De Bary: Vorlesungen iiber Bacterien, Leipzig, 1885, p. 137; also 8. Auflage, 

 Leipzig, 1900, p. 173. 



Sorauer: Handbuch fler Pflanzenkrankh. . 2. Auflage. 2. Theil, Berlin, 1886, p. 99. 



Kramer: Die Bakteriologie in ihren Beziehungen zur Landwirtschaft, etc. 

 Erster Theil. Wien. 1890. p. 145. 



Comes: Crittogamia Agrai-ia. Napoli, 1891, p. 510. 



Ludwig: Lehrbnch der niederen Kryptogamen. SUittgart, 1892, p. 90, 



Tubeuf : Pflaiizenkr. durcii kryptogame Parasiteii vernrsacht. Berlin. 1895, p. 550. 



Prillieux: Maladies des Plantes agricoles et des Arbres frui tiers et forc^stiers 

 causees par des parasites vegetaux, Paris. 1895. Tome I, p. 22. 



Frank: Die Krankheiten der Pflanzen, 2. Auflage, 2. Band, Breslau, 1890, p. 23. 



Migulaj System dei- Baketrien, 1. Bd.. Jena, 1897, ]). 320. 



Hartig: Lehrbuch der Pflanzenkraiikheiten, 3. Auflage. Berlin. 1900, p. 209. 



9 



