FUNGI. 201 



reduction to vegetable humus is expedited by the 

 growth of fungus nnycehum. From the 3318 species 

 left after deducting the foregoing, we must set apart 

 about 235 species which habitually flourish on dead 

 leaves and the stems of herbaceous plants. We thus 

 arrive at an additional seven per cent, of direct 

 fungoid disintegration. 



By no means an insignificant number of fungi of 

 the agaric type flourish on dung, almost exclusively 

 such dung as contains a large percentage of vege- 

 table matter, as horse-dung and cow-dung. The 

 large amount of nitrogeneous matter in those excre- 

 ments is eminently suitable to the development and 

 growth of the agarics ; but, although mycelium 

 rapidly penetrates the matrix and aids in its disin- 

 tegration, these species can scarcely be placed in the 

 same rank with the destroyers of wood and vegetable 

 dibris. Out of the total of 4639 species we recognize 

 some 100 as growing habitually upon dung. There 

 are also a few species which are developed upon 

 decaying fungi which might have been included with 

 the foregoing. 



We are now left with a balance of about 2983 

 terrestrial species, or sixty-four per cent, of the total 

 number of species. These produce a copious myce- 

 lium in the soil ; but this mycelium is only in a very 

 limited acceptation destructive. We can scarcely 

 separate those which are known to flourish on old 

 charcoal beds, decaying sawdust, vegetable humus, 

 or even those which ostensibly grow upon the 

 ground, but undoubtedly thrive at the cost of buried 

 vegetable matter, the sites of decayed stumps, or 



