52 HISTORY OF PHYTOPATHOLOGY 



ihre Verhiitung (The diseases of cultivated plants, their 

 cause, and their prevention). It is in several respects an 

 epoch-making book. It is the first phytopathologic 

 text to appear based upon the remarkable and far- 

 reaching discoveries and researches of de Bary, the 

 Tulasne brothers, Pasteur, and other workers of the first 

 half of the 18th century in the field of parasitology. Here 

 for the first time in a phytopathologic text (excepting the 

 little paper of Fabricius the Dane) is adopted the funda- 

 mental fact of the causal nature of fungi as pathogenes in 

 the diseases of plants. With a fine grasp of the entire 

 field of etiologic phytopathology Kiihn, while recognizing 

 the new factor, pathogenic fungi, did not deny the old 

 and generally accepted factors of weather, soil conditions, 

 animals, and parasitic flowering plants as producers of 

 disease in plants. He accepted them, but gave them 

 their proper place and value in his treatment of the sub- 

 ject. A brief of the table of contents of this the first of 

 modern texts on plant diseases will best indicate the 

 tremendous advance in the science during the first half 

 of the 19th century: 



FIRST PART 



General considerations with respect to plant diseases. 

 Introduction. 



Nature and types of disease in plants. 

 Cause of disease: 



Unfavorable climatic and soil conditions. 

 Diseases due to the influences of animals. 

 Diseases due to parasitic plants: 

 Phanerogamic parasites. 

 Cryptogamic parasites. 



