NATURAL HISTORY SURVEY 13 



attention. That the sporophores of certain species differ in ap- 

 pearance upon different hosts is well known, and this difference 

 has been seized with avidity by some of our ambitious species- 

 makers as an excuse for printing their names after many forms 

 which to the conservative botanist are not entitled to specific 

 recognition. The common mushroom, Agaricus campestris, has 

 through long cultivation taken on a number of forms, some of 

 which have been elevated to varieties by a few European writers. 



Our knowledge of the distribution of species in this country 

 is yet too limited to admit of any satisfactory study of their 

 ecological relations with the higher plants and with other fungi. 

 The matter of food-supply is a factor of first importance. In an 

 undisturbed forest a tolerably constant supply of nutrition is no 

 doubt obtained from fallen leaves, twigs, branches and trunks. 

 The overturning of a tree by the elements gives to a host of fungi 

 an available supply of food that may suffice for a number of years. 

 The wound left in a trunk by the falling of a branch may permit 

 the entrance of a colony of spores, followed by a growth of my- 

 celium which in time will permeate the entire tree, so that it 

 literally gives up its life to its host. By the action of fungi the 

 weakened trees are sacrificed to make room for those which have 

 more vigor, while dead underbrush and fallen trunks are 

 transformed into soil capable of renewing the forest growth. 

 With the clearing of the forest, the equilibrium maintained 

 for centuries between constructive and destructive vegetation is 

 abruptly terminated. A multitude of species of fungi perish by 

 starvation, the entrance of light and the withdrawal of moisture. 

 Other species are able to subsist in diminished numbers and in 

 more or less impoverished condition upon the trees, shrubs and 

 vines which have been introduced into the localities formerly 

 occupied by the forest. . 



The changes that take place in fungi thus suddenly forced 

 into a new environment have not been studied; nor have those 

 that take place in species which have gradually extended their 

 range into garden, orchard and vineyard from their adjacent 

 forest home. 



The mutual relations that exist between the great race of 

 terrestrial agarics and the higher vegetation amidst which they 

 grow, and the possible succession of species following definitely 

 the changes wrought in soil and vegetation by those that have 

 preceded them, are also matters yet to be investigated. 



Investigations have led to the conclusion that the spores of 

 certain species of Coprinus are capable of germination only after 

 they have passed through the digestive tract of some particular 

 animal. Whether this is true of other species of the genus, and 

 whether the spores of species of other genera require some similar 

 or other preparation before germination has not been fully made 

 out.* The fact that the sporophores of many species are visited 



*See Ferguson, Bulletin 16, Bureau of Plant Industry, U. S. Dep. Agr., anJ literature 

 there citeJ. 



