. A manual of botany. Botany. THALLOPHYTAâFUNGI 85 Fig. 842. called paraphyses. Each asous develops eight spores from part of its protoplasm, the rest remaining as epiptasm. In some species the fructification is in the form of a deep or shallow cup, sometimes nearly closed. This is called a â perithe- cium [fig. 841). The group of the Saccharomycetes is now generally referred to this sub-class. These plants are represented by the Yeasts, which have the power of setting up alcohohc fermentation in sugary fluids. They are simple cells of rounded or ovoid form which multiply with great rapidity b
. A manual of botany. Botany. THALLOPHYTAâFUNGI 85 Fig. 842. called paraphyses. Each asous develops eight spores from part of its protoplasm, the rest remaining as epiptasm. In some species the fructification is in the form of a deep or shallow cup, sometimes nearly closed. This is called a â perithe- cium [fig. 841). The group of the Saccharomycetes is now generally referred to this sub-class. These plants are represented by the Yeasts, which have the power of setting up alcohohc fermentation in sugary fluids. They are simple cells of rounded or ovoid form which multiply with great rapidity by a process of budding. When growing rapidly, sometimes chains of cells are formed, owing to the budding taking place before separation of the cells. Under certain conditions, usually when badly nourished, the yeast cell forms four spores by free cell-forma- tion in its interior. There is, how- ever, no sexual apparatus ever pro- duced. Each such cell may be looked upon as an ascus and the four spores as ascospores. Besides these so-called sexual pro- cesses, most of these fungi can pro- duce gonidia in great numbers. They are borne upon erect aerial hyphsB by a process of abstriction from their terminal cells called sterigmata (fig. 842). Each ste- rigma can thus produce a chain of gonidia. Sometimes the aerial hypha or gonidiophore terminates in ii'i5'., a single sterigma, sometimes it H^^l^^^ abstriction from branches near the apex, forming several. Sometimes the gonidiophores are found in numbers in special receptacles called, pycnidia. We have thus an alternation of generations in most members of the group, the ordinary mycelium being the gametophyte, and the ascocarp the sporophyte. Homologous alternation almost always occurs, many gametophytes in succession bearing only gonidia, till one appears which produces the sexual organs. In a few genera, however, no gonidia are found. A curious case of homologous alternation occurs in some. Please note
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