Cytomorphological Studies of the Ascogenous Hyphae in Four Species of Chaetomium

The genus Chaetomium was established by Kunze in 1817. Corda in 1837 improved the original description by the discovery of asci in the centrum, but he did not understand the true nature of the ascus. He did recognize, however, that it was in some way responsible for supporting the spores. Zopf contributed a well-illustrated monograph describing ten species in 1881, and Chivers recognized 28 distinct spe? cies in 1915. The form of the perithecial hairs was used as the major separation character by the early workers. Skolko and Groves in 1948 suggested that the shape and size of the perithecium and spores, in addition to the conspicuous characteristics of the perithecial hairs, provide a more practical basis for species classification. By 1953 Skolko and Groves recognized 53 species, and Ames in 1961 described 85 dis? tinct Chaetomium species. Despite the large number of species in the genus and the fact that most grow readily in culture and produce abundant perithecia, few studies have been made of the ascogenous cells.