CONCEPTS OF ORIGIN OF FUNGI 7 



Mention should be made also of such other excellent and in- 

 dispensable treatises of a purely taxonomic and classificatory 

 nature as those of Patouillard (1887), Quelet (1888), Cooke 

 (1871-1883), Massee (1892-1895), and Bresadola (1927-1932), 

 as well as Engler and Prantl's Die natiirlichen Pfla7ize?ifa?7nlien, 

 Rabenhorst's Kryptogtmicn Flora, the Sydows' Monogvaphia 

 Uredinearimi, Oudemans' Eninneratio Systematica Fimgorimi, 

 and Seymour's Host Index of the Fungi of North America. This 

 list of essential works is incomplete without Saccardo's Sylloge 

 Fimgonim, which now comprises twenty-five volumes, the first 

 having appeared in 1882. This work purports to contain brief 

 descriptions in Latin of all known fungi, about 80,000 species, 

 only an occasional description being inadvertently omitted. 



Concepts of origin of fungi. Throughout the period extend- 

 ing to the middle of the nineteenth century the theory of spon- 

 taneous generation dominated all explanations of the origin of 

 microscopic life. Fungi were supposed to be generated by the 

 substratum upon which they were found; it seemed impossible 

 to overcome the influence of this ancient dogma. Persons inter- 

 ested in the classification of fungi continued meanwhile to de- 

 scribe and name them as separate entities. Observations that 

 fungi occur on the surface of living seed plants continued to be 

 recorded, and proofs of the ability of fungi to produce disease 

 accumulated. Fontana's observations (1767) on Puccinia graiii- 

 ijiis convinced him that the rust is an independent plant that 

 probably produces "seed." Prevost (1807) proved that the 

 "globules" in bunted wheat are the spores of the pathogen. 

 Nevertheless Unger (1833), among others, insisted that the tis- 

 sues of the plant underwent a metamorphosis to become the 

 fungus. The evidence of Prevost, Fontana, and other workers, 

 in its entirety, failed to shake the foundation of belief in spon- 

 taneous generation. The change in point of view came primarily 

 as the result of the brilliant and convincing experiments of Pas- 

 teur, in which he demonstrated that microbes are air-borne, that 

 they reproduce, giving rise to others like themselves when grown 

 in culture, and that their activities induce fermentations. 



During the period in which Pasteur was making these revolu- 

 tionary experiments that led to the discoveries of microbes as 

 causal agencies of human and animal diseases, the foundations of 

 knowledge regarding fungi as the cause of plant diseases were 



