CONSTITUENTS AND HABITS i 9 



second, it occasionally occurs, and in the third, it is not certainly 

 known to exist. 



Besides the above classes, there are two groups of low organisms, 

 the bacteria and slime moulds, which are often associated with the 

 true fungi. The tendency at present is to treat them separately. 

 Many botanists, indeed, regard the slime moulds as animals. If 

 treated with the true fungi they would form two classes addiuonal 

 to those above noted and stand below them : the Myxomycetes 

 and the Schizomycetes. It is better, however, to regard the 

 Mycetozoa (slime moulds) as a group of organisms coordinate with 

 the phylum Thallophyta, and the bacteria with their evident 

 close alliance to the blue green algae i^Cyanophyceae) maybe best 

 regarded as forming together a group (Schizophyta) coordinate 

 with the true algae on the one hand, and the true fungi on the 

 other. 



It must be constantly borne in mind that these larger groups 

 are heterogeneous assortments of plants united together, not so 

 much because of actual phylogenetic relationships as from the 

 possession of certain characters that indicate a real, though some- 

 what artificial, resemblance. 



Since some slight innovations in group names are to be intro- 

 duced in succeeding chapters, it is, perhaps, well to interpolate a 

 general statement on group nomenclature. Species among fungi, 

 as elsewhere, are recognized as the smallest groups of distinct 

 things, such as might have been produced from the same spores 

 or mycelium ; associated species with like characters form 

 genera. To the genus and species we give the Latin double 

 name as among all other organic forms of life, e. g., ADianiia 

 caesarea. It is fortunate that for the majority of fungi there are 

 no common or "popular" names, for there is no necessity for 

 a double series, Amanita caesarea contains no more letters than 

 " Caesar's mushroom," and is at once a more direct and elegant 

 method of citation. Like genera are united into famihes which 

 are normally named from some characteristic or representative 

 genus, with the uniform termination — aceae, e. g., Agaricaceae 

 from the genus Agariciis, Hydnaceae from the genus Hydiiiim. 

 Closely related families are united into orders whose name is like- 

 wise derived from the name of a characteristic genus. The ordinal 

 name according to a recent, but important innovation, has the ter- 



