. Comparative morphology of Fungi. Fungi. LABOULBENIALES 395 which can branch and proceed independently to form asci. By this insertion of a new phase, the activity of the gametangia increases; from a gametangium may arise several gonotoconts. Thus, phylogenetically considered, the reduction caused by the privileging of a small number of gametangial nuclei was overcome. Still the phylogenetic development of the Ascomycetes is most obscure. We need only cite the contradictions between the Pencillium and the Pyronema types, the Taphrina type and the Laboulbenia type. In any case, within the Plec
. Comparative morphology of Fungi. Fungi. LABOULBENIALES 395 which can branch and proceed independently to form asci. By this insertion of a new phase, the activity of the gametangia increases; from a gametangium may arise several gonotoconts. Thus, phylogenetically considered, the reduction caused by the privileging of a small number of gametangial nuclei was overcome. Still the phylogenetic development of the Ascomycetes is most obscure. We need only cite the contradictions between the Pencillium and the Pyronema types, the Taphrina type and the Laboulbenia type. In any case, within the Plectascales has somehow been developed the hook form of the Pyronema type which, on account of its distribution in the Ascomy- cetes and its character as bridge to the clamp mycelium of the Basidio- mycetes, has become the most significant form of ascogenous hyphae. While in Pyronema confluens, the hook tip can occasionally fuse with the stipe cell, whereby the stipe nucleus migrates into the tip and develops it to a branch, in some higher forms, as Helvetia elastica and Parmelia acetabulum, this fusion of hook tip with stipe cell becomes the rule. Only in them the nucleus of the tip migrates back into the stipe, so that branch- ing is absent and clamp formation is entirely similar to that of the Basidiomycetes. Simultaneously with the degeneration of sexuality, the ascogenous hyphae lose their specific character. They still arise only as a result of pseudogamous copulation between vegetative hyphae somewhere in the tissues of the fructification, and penetrate it for a long distance. Since these ascogenous hyphae more and more assume the character of vegeta- tive hyphae, it is comprehensible in certain forms, as in Ascocorticium, that asci appear to arise directly from vegetative mycelia. If we imagine this development proceeds one step further, in that the ascogenous hyphae (like vegetative hyphae) become adapted to independent food intake (which is perhaps already the case in so
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