PARASITES ON FUNGI 179 



lively furnishing all the requirements for a certain set of 

 species, that the battles between differently coloured spore- 

 groups take place. 



Various species of Boletus, Paxillus, Flammula, and 

 others, with coloured spores, are characteristic pine-wood 

 fungi ; in oak and other woods of broad-leaved trees, white- 

 spored species predominate, whereas in pastures and open 

 downs pink-spored species are common, as species of 

 Leptonia^ Entoloma, Clitopilus, etc. 



The sporadic appearance of fungi is a fact well known to 

 mycologists, and is not to be explained by climatic condi- 

 tions. During certain seasons white-spored species largely 

 predominate; during other seasons brown-spored repre- 

 sentatives are most in evidence. In certain seasons some 

 of the species generally most abundant and cosmopolitan 

 are almost entirely absent. We are at present unable to 

 offer even a suggestion for this condition of things. 



PARASITES ON FUNGI 



Fungi are by no means immune against the attacks of 

 parasites which consist of other species of fungi. This is 

 true of all the families. 



In the Phycomycetes the species of Mucor are especially 

 victimised ; forms of Piptocephalis, Chaetocladium, Disptra, 

 SyncephaliS) and Dimargaris being among the parasites 

 found on members of this genus, in all cases living on the 

 sporangiophores. 



Species of Rhizidium, Olpidium, Pythium, Rozella, etc., 

 are parasites in the oospores, antheridia, or hyphae of 

 various members of the Saprolegnieae. 



In the Ascomycetes various species of Peziza are attacked 



