Micromorphology of the lower Hymenomycetes.

To classify the lower Hymenomycetes, not often distinguished by their shape, colour or hymenial configuration, mycologists eventually turned to the microscope to seek more exact diagnostic characters. As far as the circumscription and identification of species is concerned, microscopy has revealed many useful characters. But the other ideal of taxonomy, namely a natural classification, is still far from realisation as the significance of facts already observed has only partially been evaluated. This paper is an attempt to review with illustrations the morphology of the microscopic organs found in the lower Hymenomycetes, special attention being given to the basidium. For amplification examples are cited from other groups of fungi as well. Some standard of terminology has been aimed at, particularly with regard to the basidium. The conclusions reached are that Linder’s terminology for the basidium is unacceptable as it over-simplifies this organ, w7hile Neuhoff’s terminology is based on homologies which are unacceptable. Moreover, Neuhoff’s terminology is flexible and in many instances would vary according to the subclass in which a particular fungus is classified. We believe, with Donk, that the place or stage of karyogamy, and the place or stage of meiosis, are fundamentals which should be used in formulating a terminology for basidia. The new term protosterigma coined by Dr. M. A. Donk, is published here for the first time with its originator’s generous permission. The term is explained in a note on sterigmata in general provided by Dr. Donk, which should be read in conjunction with this paper.