610 COMPARATIVE MORPHOLOGY OF FUNGI 



dinales and have often been called teliospores. Whether they are hom- 

 ologous with them in the life cycle is still uncertain ; in the forms of the 

 type of Entyloma Nymphaeae, where they are formed terminally on small 

 branches, this conception is plausible; for Ustilago Tragopogonis-pratensis, 

 in which they arise from intercalary swellings, we possess no analog in 

 the Uredinales. The only possible parallel at present are the chlamydo- 

 spores of the Protomycetaceae. The smut spores of the Ustilaginales 

 are also called chalamydospores. The chlamydospores of the Proto- 

 mycetaceae germinate with sporangia with endogenous sporangiospores, 

 while those of the Ustilaginales with basidia-like promycelia. 



The morphological evaluation of this promycelium encounters great 

 difficulties. Many older authors agree with Brefeld in considering it 

 a conidiophore, or a hemibasidium which is in the process of stabiliza- 

 tion to a basidium. The lowest stage was shown by Ustilago longissima, 

 in which the sprout cells (considered by Brefeld as conidia) develop 

 repeatedly to " conidiophores" of indefinite structure or to mycelia 

 (Pro-U stilago). A middle stage was shown by U. Vaillantii in which the 

 "conidiophores" (sprout cells) could arise in unlimited sequence, but 

 have become constant in form and septation (Hemi-U stilago). The 

 highest stage was shown by the type of U. violacea, in which the 

 conidiophore was stabilized both in form and place of formation, 

 appearing as a typical basidium only on the germination of the smut 

 spores (Eu-U stilago). According to this conception, then, the Ustil- 

 aginales should not be classed intheBasidiomycetes,but placed in a special 

 class, the Hemibasidii, forming the transition from the Phycomycetes to 

 the Basidiomycetes. 



According to the point of view presented in this book, the state of 

 affairs is quite the opposite. The promycelium of the Ustilaginales is 

 not a hemibasidium (a basidium in statu nascendi) but a metabasidium 

 (a basidium in degeneration). For this conception the following facts 

 may be set forth: Already in the Uredinales some forms, e.g., Puccinia 

 Malvacearum (p. 581), have a tendency to omit the formation of basidio- 

 spores and to permit the basidial cells to germinate directly by germ tubes. 

 This may be indicated as the first symptom of a development which, in 

 respect to the morphological differentiation of the gonotoconts, proceeds 

 in the reverse sense to that described for the transition from the Phyco- 

 mycetes to the Ascomycetes. While in passing from the Phycomycetes 

 to the Ascomycetes meiosis became fixed in a sporophore, the sporangium, 

 which as gonotocont has developed to an ascus and finally to a basidium, 

 thereafter, in the highest Basidiomycetes, the sporophore characteristic 

 of these gonotoconts again begins to vanish. With the degeneration of 

 sexuality, the gonotoconts also lose their typical form and again germi- 

 nate directly to mycelia without spore formation as they did in the Phyco- 

 mycetes. That these phenomena first appear in parasitic forms agrees 



