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INTRODUCTION TO THE STUDY OF FUNGI 



bodies do not germinate at once, but hibernate for a short time, 

 generally varying from three weeks to three months, commonly 

 two months, and during this period they become slightly 

 spinulose and faintly tinted with a brownish hue. These 



little bodies, there- 

 fore, hibernate after 

 the manner of rest- 

 ing spores, and it 

 is possible that 

 many of them rest 

 during the entire 

 winter." * Assum- 

 ing that the seg- 

 ments of theconidia 

 of Fusarium are 

 capable of forming 

 a thicker integu- 

 ment, and hibernat- 

 ing through the 

 winter, there is no 

 reason why, from 

 analogy, other 

 conidia, belonging to other genera, may not be capable of 

 a like modification, and thus aid in the perpetuation of the 

 species. It is almost certain that the thin -walled conidia 

 are unable to survive the winter, and hence the question 

 arises as to how the rejuvenescence of the Hyphomycetes is 

 assured; for, although in some cases a perennial mycelium may 

 explain the difficulty, it cannot do so in the parasitic species, 

 such as Ramularia, Ovularia, and Cercospora, where the 

 destructive fungus appears as a pest on the living leaves, year 

 after year. As an example, the leaves of the " ground ivy " 

 (Glechoma) through the autumn will present hundreds of leaves 

 with the white blotches of Ramularia calcea, sometimes every 

 leaf more or less affected, and during the winter most of these 

 leaves will die and decay. With the spring there will be a 

 carpet of green leaves again, without a spot of Ramularia; but 

 as summer advances the pest appears as profusely as ever, and the 

 1 Diseases of Field and Garden Crops, by W. G. Smith, London (1884), p. 33. 



Fig. 130. — Conidia of Fusarium. B, mature conidium ; 

 C, cells germinating ; D, cells separating, and be- 

 coming rounded ; E, separated cell after a period of 

 rest-germinating. After Smith. Macmillan and Co. 



