1890.] PUBLIC DOCUMENT— No. 33. 205 



the mycelium under long-continued observation. The 

 spores and spore-bearing organs in the different stages of 

 the same fungus may represent wholly different types of 

 structure ; so that the different forms have been, and, in the 

 great majority of cases, still are, described and known under 

 different names, as distinct fungi. This diversity of form, 

 characteristic of the life-cycle of so many fungi, is known as 

 PLEOMORPHiSM. The subject is but just beginning to be 

 understood, and its study is only begun. Consequently our 

 knowledge of the whole matter is extremely fragmentary and 

 unsatisfactory. 



The fungi, like other plants, exhibit among themselves 

 widely different types of structure, and may be separated 

 into very distinct groups ; while, within the limits of these 

 groups, they show in greater or less degrees that similarity 

 of organization and development which indicates descent 

 from common ancestors, and consequent near relationship. 

 These likenesses and differences enable us to arrange the 

 fungi for convenience of study and discussion in a more or 

 less natural order, th#>ugh our knowledge is still very far from 

 being sufficiently complete to afford us an arrangement 

 which at all fully represents their relationships. It will be 

 a great convenience, in future discussions, to have a general 

 outline of the classification of the fungi and related groups ; 

 and the following is presented with a view to meeting this 

 need. It is hoped that it may prove useful for reference, 

 and sufficiently full, taken in connection with the preceding 

 general account, to facilitate an intellio-ent understandimj of 

 discussions of particular fungous diseases. If any reader 

 should feel, after reading this necessarily very brief and 

 imperfect sketch, a desire for more detailed information con- 

 cerning any fungi, the writer will be glad to render all pos- 

 sible assistance. In the folio wino- brief accounts of the 

 various groups, attention has been given especially to those 

 which include parasites on cultivated plants. The best 

 available English name has been given to each group, and 

 after the English name will be found, in each case, the 

 name, in parentheses, by which the group is known to 

 botanists. 



