20 . PREAMBLE. 



we take exception in favour of d priori 

 determination. 



It should be borne in mind that fungi 

 which grow upon trees are not likely to be 

 found growing on the ground, and that 

 those which inhabit pastures should not 

 be sought in woods. In most species there 

 is a great persistence in habit, and, not- 

 withstanding some variability in form, size, 

 and colour, comparative permanence in 

 character, or in such characters as are 

 relied upon for the discrimination of species. 

 A species which possesses a ring upon the 

 stem, for instance, or warts upon the 

 pileus, always has them, unless denuded 

 by accident. Hence the different species 

 may be distinguished by specific characters, 

 as in plants of a higher organization, so 

 that the ordinary process of determination, 

 as employed in other departments of botany, 

 is equally applicable here, and the results 

 are equally satisfactory. 



The assumption that fungi of the same 

 species, growing in different localities, may 



