65 



making the forms and causes of disease more easily comprehended by the 

 layman, by means of colored illustrations. On this account, without regard 

 to special works on fungi, we often find the text supplemented by colored 

 pictures of the habit of growth. An attempt to present the most important 

 diseases in the form of a portfolio with short descriptions of the figures on 

 the plates could be undertaken only after a more widely extended under- 

 standing of the importance of this branch of knowledge had insured a suf- 

 ficient number of purchasers. Accordingly, since 1886, Paul Parey of Berlin 

 has issued Sorauer's "Atlas der Pflanzenkrankheiten," of which six folio 

 numbers have already been published. The especial care used here, in hav- 

 ing the dififerent colors true to nature, made the price such that the publica- 

 tion had a smaller circulation among practical workers than in scientific in- 

 stitutes, and accordingly a need was gradually shown for the publication of 

 a less expensive work. This appeared under the title, "Atlas der Krankhei- 

 ten und Beschadigungcn unserer landwirtschaftlichen Kulturpflanzen," 

 edited by O. Kirchncr and H. Boltshauser and published by ITlmer, Stutt- 

 gart. This is now completed in six numbers. ATcanwhile the Deutsche 

 Landwirtschafts-Gesellschaft discovered, by its publication of "Pflanzen- 

 schultz," that at present the time is ripe for the extension of the knowledge 

 of diseases among practical agriculturalists, and that it can be carried through 

 most successfully by such brief guides. The society published the third 

 edition in 1904, revised by Sorauer and Rorig, with seven carefully pre- 

 I.ared plates. The "Atlas des Conferences de Pathologie vegetale" by 

 Georges Delacroix, Paris T90T, should be mentioned as of special service to 

 the systematic study of diseases. This gives the most important diseases of 

 cultivated plants in 56 plates in black and white. In 1902 Delacroix pub- 

 lished by order of the French Agricultural Department a small work, "Mala- 

 dies des plantes cultivees," Paris, which was written chiefly for general use 

 and is supplemental to the above. 



The most significant scientific advance is the publication of monographs 

 covering the separate fields of disease. This method has also appealed 

 especially to recent workers in plant pathology. In accordance with the im- 

 portance of the disease, thorough study has been devoted to the rust fungi, 

 especially of grain. In 1894-95 the German edition of a 463-page work by 

 Jakob Eriksson and Ernst PTenning was published, — "Die Getreideroste, 

 ihre Geschichte und Natur. sowie Mafsregeln gegen dieselben," Stockholm. 

 This work, which attracted much attention, appeared as a volume of the 

 "Meddelanden fran Kongl. Landtbruks-Akademiens Experimentalfalt," and 

 its 13 colored plates show clearly the diseases due to grain rusts. It proves 

 the specialization of parasitism in the fungi of grain rusts. Besides this, the 

 work takes up the discussion of the determinative factors and tests the posi- 

 tion, the physical and chemical constitution of the soil, the previous cropping, 

 time of seeding etc. 



In 1904, H. Klebahn published an equally careful work with a larger 

 field and based on his personal studies, entitled :— "Die wirtswechselndcn 



