CHANGES IN SYSTEMS OF CLASSIFICATION 33 



mycetes is 450, of Phycomycetes 1000, of Ascomycetes 12,120, 

 Basidiomycetes 13,430, and Fungi Imperfecti 10,500, making a 

 total of 37,500 species. They further indicate that only about 

 one-third of all species have been described. So far as informa- 

 tion warrants, in all present-day systems the division of each of 

 these classes into orders, families, tribes, and similar subdivisions 

 indicates phyletic relationships and evolutionary developments, 

 the simplest being placed first and the more complex following 

 in an ascending series. All of them therefore are ordinarily re- 

 garded as natural systems, but there remains much in classifica- 

 tion that is arbitrary or has been devised by man for his mental 

 convenience, and hence is purely artificial. For example, the 

 Agaricaceae are divided into tribes on the basis of color of spores 

 en masse, tribal names being Leucosporae, Rhodosporae, Phaeo- 

 sporae, Ochrosporae, and xMelanosporae. Similarly color, shape, 

 and septation of spores, either as separate characters or in com- 

 bination, especially among the Ascomycetes and Deuteromy- 

 cetes, furnish the basis for such groupings as Amerosporae, AI- 

 lantosporae, Hyalodidymae, Phaeodidymae, Hyalophragmeae, 

 Phaeophragmeae, Dictyosporae, Scolecosporae, and HeHco- 

 sporae. 



Any system of classification is successful only if its use will 

 enable the worker to identify an unknown organism conveniently 

 and accurately and at the same time relate it to known organisms. 

 Years must still elapse, however, before the vast expanse of ig- 

 norance will be sufficiently carefully charted to enable the stu- 

 dent to know that he has closely approximated a natural system. 

 Meanwhile evidence will have accumulated to clarify the ques- 

 tion of \\ hether the fungi are a monophyletic series derived from 

 filamentous green algae, whether they are a polyphyletic as- 

 semblage derived from different groups of green and red algae, 

 or whether they are a distinct phylum derived from protozoan an- 

 cestry. This third hypothesis, voiced by Martin (1941), appears 

 to fit present-day facts most nearly. 



Although many systems of classification have been proposed, 

 the few examples which have been mentioned indicate the evo- 

 lution of present-day systems. Certain investigators would now 

 exclude bacteria and slime molds from the Fungi. Many would 

 separate the Fungi from the Algae, giving each a coordinate 



