324 



CLASS ASCOMYCETEAE 



Fig. 104. Aspergillales, Family Aspergillaceae. Monascus ruber van Tiegh. Sexual 

 reproduction. (A) Ascogone growing up sympodially at base of elongated antherid. 

 (B) Ascogone separated by septum from hypha. (C) Ascogone divided into a basally 

 located oogone and a trichogyne which has formed an opening to the antherid. (D) 

 Antherid has collapsed and the nuclei have passed through the trichogyne into the 

 oogone. (E) Two investing hyphae are growing up from just below the oogone. A 

 conidium is shown on the antheridial branch. (F) Perithecium wall completed; one 

 of the curved ascogenous hyphae is shown with three terminal asci, successively 

 younger from apex toward base. (G) Section of mature perithecium with ascus walls 

 mostly dissolved. (Courtesy, Young: Am. J. Botany, 18(7):499-517.) 



as an antherid. From this ascogoniiim arise binucleate cells which give 

 rise to ascogenous hyphae. (Fig. 104.) 



The formation of the ascus has been reported by Schikorra to take 

 place by the hook method in Monascus but this is denied by Young. 

 DeLamater (1937) has demonstrated the formation of croziers in Arachni- 

 otus aureus (Eidam) Schroet., of Family Gymnoascaceae. In general one 

 or more of the binucleate cells at the end of an ascogenous hypha enlarge, 

 the nuclei fuse and the young ascus is initiated. The perithecium is formed 

 by the growth of hyphae from near the point of attachment of the 

 ascogonium. 



In perhaps the majority of species investigated cytologically the 

 mycelial cells and the conidia are plurinucleate. The young ascogonium 

 and young antherid may be plurinucleate or uninucleate. It is difficult to 

 determine which represents the more primitive condition. 



Several families are recognized in this order, following Fischer (1896) 

 in the main. Those first to be considered show the closest affinity to the 

 Erysiphales and may well have arisen from or have given rise to that 

 order. The sexual organs and mode of origin of the perithecium are quite 

 similar in some of the Aspergillales to the corresponding structures of the 

 Erysiphaceae. If the short ascogenous hyphae of the latter should become 

 longer and of various lengths, pushing in among the tissues of the central 



