276 PART III. THE CLASSIFICATION OF PLANTS. 



loped, but the male organs are functionless; still the female organs 

 produce oospores, but they do so parthenogenetically. In the 

 majority of the apparently sexual Ascomycetes, even when both 

 kinds of sexual organs are present (e.g. Erysipheas, Penicillium. 

 Sordaria) it is a question if any sexual process takes place ; in 

 others, no male organ is present (e.g. Chsetomium, Melanospora) ; 

 in others again (e.g. Xylaria), the female organ is rudimentary ^ 

 and in yet others (e.g. Claviceps, Cordyceps, Pleospora) it lias 

 entirely disappeared. Yet in all these cases an ascocarp is pro- 

 duced, either parthenogenetically from the female organ, or vegs- 

 tatively from the mycelium. In the ^Ecidiomycetes, though there 

 is apparently no female organ, yet a fructification termed an 

 cpcidium, which seems to be homologous with the ascocarp of 

 the Ascomycetes, is produced in most forms. In the Basidiomy- 

 cetes, although they are the most highly organised Fungi, there 

 are no sexual organs, and no fructification is produced which is 

 homologous with the ascocarp of the Ascomycetes. 



The sexual organs, with the exception of those of some Ascomy- 

 cetes, are unicellular. They are either quite similar to each other, 

 as in the Zygomycetes and some Ascomycetes (e.g. Eremascus), 

 when they may be termed gametangia ; or they may be more or 

 less differentiated, as in the Oomycetes, and in some Ascomycete& 

 (e.g. Erysiphese, Collema, etc.), as male and female. 



The male organ is a pollinodium in the Oomycetes and in some 

 Ascomycetes (e.g. Pyronema, Erysipheae, Ascobolus); it is generally 

 unicellular but sometimes multicellular (e.g. Ascobolus). As it is 

 developed in close proximity to the female organ, fertilisation is 

 effected, in these forms, by absorption of the cell-walls at the 

 point of contact of the two organs, or the development of a tube 

 placing their cavities in communication. 



In other Ascomycetes (e.g. Collema), what appears to be the 

 male organ is a unicellular or multicellular filament, termed a 

 sterigma, at the apex of which male cells (spermatia) are succes- 

 sively formed by abstriction. The sterigmata are developed in 

 great numbers together within a special receptacle termed a 

 spermogonium. In these forms the male and female organs are 

 widely separated, and the male cells are conveyed by means of 

 water to the female organ. Spermogonia also occur in the 

 ^Ecidiomycetes. 



The female organ is either a unicellular closed oogonium (Oomy- 

 cetes), or a unicellular or multicellular archicarp (Ascomycetes) 



