i;8 TEXT-BOOK OF FUNGI 



question under consideration is the practical absence of 

 special contents, alkaloids, poisons of various kinds, cor- 

 roding substances, etc., in the cells of the black group, and 

 their gradual increase in number and potency, through 

 the purple, brown, pink and white groups, in the last 

 named being most generally distributed. 



It is well known to every field mycologist that when a 

 struggle between species belonging to different colour 

 groups takes place, for a locality equally suitable to both 

 so far as outside conditions are concerned, the white-spored 

 species or its nearest ally invariably predominates over a 

 member belonging to a darker-spored group. The white- 

 spored Clitocybe and the pink-spored Volvaria respectively 

 ousted the purple-spored mushroom from the beds. On 

 the other hand, the purple-spored mushroom does not 

 tolerate the black-spored Coprinus to encroach on its 

 domain. Why this should be is not known ; can it be due 

 to the presence of some potent cell-content used by the 

 higher fungi against the mycelium of the less perfectly 

 protected lower groups? At all events this condition of 

 things points to the fact that the monopoly of a given site 

 rests more on the power of the parties competing than on 

 external conditions. Either could be happy alone, but 

 equal privileges are not tolerated. 



On the other hand, fungi are not indiscriminately scat- 

 tered, even in such a limited area as England. We have 

 respectively characteristic upland, lowland, and swamp 

 species. Apart from parasites the fungus flora of a pine 

 wood differs from that of a beech wood or an oak wood. 

 This, however, may be accounted for by the fact that the 

 humus of a pine wood is different to that of a beech or an 

 oak wood, or a pasture. It is within these areas, respec- 



