86 SUMMARY OF CURRENT RESEARCHES RELATING TO 



traced back to a single cell or ascogenous filament, as also was 

 the case in Melanospora, the perithecial form of Botri/tis Bassiana. 



As regards the general structure and position of the Ascomycetes, 

 Brefeld regards the three following as the most important points: — 

 1. The degradation of the various forms of fructification ; 2. The 

 disappearance of sexuality, either from the forms of fructification or 

 with them ; 3. The reversion of sporangia to conidia. All known 

 fungi he divides into the tv/o great divisions of Phycomycetes and 

 Mycomycetes. To the Phycomycetes belong two classes, viz. : — 

 1. Zygomycetes (Mucorineae, Thamnidieae, Choanephoreae, Chaeto- 

 cladiacefe, and Piptocephalideae) ; and 2. Oomycetes (Chytridiaceae, 

 Saprolegnieae, Peronosporeae, Entomophthoreae, and Ustilagiueae). 

 The Mycomycetes are com^Dosed of three classes, viz. : — 3. Asco- 

 mycetes ; 4. ^cidiomycetes ; and 5. Basidiomycetes. The lowest 

 forms of fungi he regards as nearly related diverging branches from 

 a common origin. The same is the case also with the higher forms. 

 In both higher and lower forms he finds the same tendency for the 

 sporangia to revert to the condition of simple conidia, and for the 

 fructification to lose its sexuality. 



The multinucleated condition of the cells of many unicellular 

 Thallophytes Brefeld regards as an indication that they are descended 

 from multicellular forms from which the cell-walls have disappeared. 

 The family in which this degradation has been carried to the greatest 

 extent is the Myxomycetes, constituting a third great division of 

 the Fungi, in which the cell- walls even of the spores have 

 disappeared, the vegetative life being carried on by permanently 

 naked cells. 



Both the higher and lower Fungi may be traced back to a 

 sporangiferous parent-form, probably green and belonging to the 

 Algae, in which there was already a difi'erentiation into sexual and 

 non-sexual forms of fructification. Sexuality was therefore the 

 original condition of all Fungi, but has in many cases disappeared, a 

 phenomenon not seen elsewhere in the vegetable kingdom. All three 

 forms of fructification, or only some, or none, may have degenerated 

 to the condition of conidia. Hence we may get forms with only male, 

 others with only female organs. The number of forms of fructification 

 may also be increased beyond three, as in the ^cidiomycetes. There 

 may also be in addition a pure vegetative mode of increase, by the 

 breaking up of the mycelium, or the separation of shoots. In these 

 cases all other modes of reproduction, all kinds of fructification, 

 may disappear, and propagation take i^lace in a vegetative way only. 



The pollinodia of the Ascomycetes not having the male character 

 assigned to them by de Bary, Brefeld regards the ascocarp as an 

 originally female mode of fructification which has lost its sexual 

 character ; the spermatia indicating, in their inability to germinate, 

 their original male character. The conidia are the result of degrada- 

 tion of the asci. In the Erysiphete, Pyrenomycetes, and Disco- 

 mycetes, the apothecia or perithecia may, from analogy, be regarded as 

 similar degraded female organs ; in the ascojihores of Exoascus and 

 Taphrina both sexual and non-sexual forms of fructification occur. 



