BESSEY: MYCOLOGY 251 



end). He divides this class into three series, leading to three lines of develop- 

 ment. These are based on the asexual reproduction as follows : sporangia alone, 

 sporangia and conidia, and conidia alone. The first group has fungi witli only 

 the fully developed sporangia, as in Mucor, Rhizojnis, etc., or with both spo- 

 rangia and sporangioles, as in Thamnidium. By reduction of the s]iorangioles 

 to indehiscent, monosporous cells arose the conidia of the Choanephoraceae, 

 forming the second group, in which true sporangia as well as these conidium- 

 like sporangioles occur. Again from Thamnidium, by a similar reduction of the 

 sporangioles to conidia and the complete loss of the true sporangia, came the 

 third group of which Chaetocladium is characteristic. 



Tlie higher fungi, which Brefeld calls Myeomycetes, have entirely lost their 

 sexuality. In the Ascomycetes the ascus is derived from the sporangium of some 

 mold, like Choanephora and the conidia from the reduced indehiscent sporan- 

 gioles. An intermediate group, the Hemiasci, is postulated, including fungi in 

 which the sporangium, now well on its way to become an ascus, still remains 

 with a large indefinite number of spores, the final step being the reduction of 

 this large number of spores to a definite number, usually eight. From the com- 

 pletely conidial Mucorales, such as forms of the same degree of development as 

 Chaetocladium, Brefeld postulates the origin of the Hemibasidii, in which the 

 conidiophore of this fungus has been reduced to a several-celled protobasidium 

 with an indefinite number of spores. Here are the Ustilaginaceae and Tille- 

 tiaceae. The former gives rise, with the number of spores reduced to four but 

 with the basidium still several-celled, to the Protobasidiomycetes, including the 

 Uredinales and AuricuJaria and Tremella and Pilacre. From the vicinity of 

 Tilletia, with its one-celled promycelium or protobasidium, arose the Autobasi- 

 diomycetes, with their spore number reduced to four. F. von Tavel (1892) de- 

 votes a very interesting little book to a discussion of the fungi in the light of 

 Brefeld's classification. 



Dangeard goes a step further in separating the fungi completely from the 

 algae, thus forming two independent series. Both are assumed to have evolved 

 from Protozoa of the group Flagellata. The algae became plants at the point 

 of evolution where their flagellate, chlorophyll-containing ancestors lost the 

 power of engulfing particles of food. The fungi arose from the flagellates that 

 lacked chlorophyll, likewise at the point where they no longer took into their 

 cells the particles of food. Thus the fungi are a kingdom parallel to the plant 

 kingdom, on the one hand, and to the animal kingdom, on the other. It is worthy 

 of note that G. W. Martin (1932) makes a somewhat similar suggestion. 



Wilhelm Zopf (1890) follows a classification similar in part to that of Bre- 

 feld, but places the Ascomycetes last. In these he goes from the simple forms, 

 like Saccharomyces, Endomyces, Gymnoascaceae, to, at the peak, the Pezizales. 

 He recognizes the formation of ascogones in many Ascomycetes and even the 

 union of these in Pyronema, with club-shaped "pollinodia," but expresses doubt 

 as to their real sexual function. 



The classification of fungi followed in the first edition of Engler and Prantl 

 (1897-1907) is, in its main features, the same as that of Brefeld. In the second 

 edition (1926-1938) the main features are retained with some modifications 

 made necessary by the cytological confirmation of the actual occurrence of sexu- 

 ality in the higher fungi as well as in the Phycomycetes. Yet this fact has not 



