A. Introduction to the Classification of 

 Fission-fungi. 



I. The Fundamental Ideas of Botanical Classification 

 Applied to Fission-fungi. 



All individual plants which upon careful examination 

 are alike and transmit their characteristics to their descen- 

 dants are designated as representatives of a botanical vari- 

 ety (species). 



The nomenclature of the animal and vegetable kingdoms 

 employed at present is founded upon the assumption that 

 a very definite number of varieties of plants (species) are 

 present upon our planet which can certainly be distin- 

 guished from each other by characteristics visible with more 

 or less ease, and which, through propagation, reproduce 

 themselves unaltered in all essential characteristics. A 

 number of such species possess certain common character- 

 istics and thus exhibit a certain close relationship, — these 

 species are placed together in a genus. As genus charac- 

 teristics it is only allowable in general to select actual 

 characteristics, usually those concerning the structure of 

 the organs of reproduction. Some genera consist of single 

 species, others include hundreds. A group of genera 

 forms a family. 



In certain groups of the vegetable kingdom the actual 

 circumstances suit this scheme very well. The individu- 

 als can be divided easily into a number of sharply charac- 

 teristic varieties, not connected by any transition ; a num- 

 ber of varieties group themselves naturallj^ into a genus, 

 and the genera constitute a natural, sharply defined family. 



The conditions are nearly so in the case of the German 

 malvacese. The family is sharply characterized ; it con- 

 sists of four genera, and each genus includes from one to 



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