Fossil Fungi, 45 



not clearly understood, and it is further known that no 

 one set of circumstances is equally favourable to the 

 development of all species ; for example, a survey of 

 the reports of our various fungus forays, extending 

 over several years, which refer almost entirely to the 

 Agaricinese, reveal such statements as the following: — ■ 

 A great scarcity of white-spored species ; Cortmarii 

 especially abundant ; brown-spored species practically 

 absent, &c. The same remarks apply to the minute 

 parasitic species. It has been noted that after a 

 succession of two or three dry seasons there is always 

 a scarcity of fleshy fungi, however favourable the 

 following season may be. This favours the idea that 

 the spores of the Agaricinese do not retain their 

 vitality longer than a single season. As a rule, it may 

 be stated that in temperate regions, dry weather, 

 especially if the temperature is high, checks the de- 

 velopment of fungi, whereas moist weather with a 

 sufficiently high temperature, favours their develop- 

 ment, but moisture alone does not effect this object. 



Fossil Fungi. 



The tissues of the majority of fungi are ill adapted 

 for preservation in a fossil state, hence the group is 

 but poorly represented. Nevertheless, evidences are 

 not wanting to prove the existence of fungi at geologi- 

 cally early periods. Mr. Worthington G. Smith has 

 described ^ and figured a member of the Phycomycetes 

 resembling the recent genus Peronospora, found in 



^ Gard. Chron., Oct. 20, 1887 ; also in " Diseases of Field and 

 Garden Crops," p. 331. 



