OEDER ASPERGILLALES (PLECTASCALES) 323 



interior of the perithecium. The latter, as in the Erysiphales and Sphae- 

 riales, consists of a firmer exterior cortex (this is sometimes of loose 

 hyphae) and a thin-walled interior portion. Some of these thin-walled 

 cells are pushed aside or destroyed as the branching ascogenous hyphae 

 grow among them so that eventually the asci appear to be imbedded here 

 and there in the internal ''nucleus" of the perithecium. Finally most of 

 these interior cells as well as the ascus walls and the remains of the asco- 

 genous hyphae are dissolved, leaving the ascospores loose in the peri- 

 thecial cavity. True ostioles are lacking in most genera of this order. In 

 the Aspergillaceae they are present in Microascus and Emericella. If the 

 suggestion of Nannfeldt (1932) is followed and the Ophiostomataceae and 

 Chaetomiaceae are transferred from the Sphaeriales to this order these 

 families will add to the ostiolate forms in the order. The asci are formed 

 at the ends of the ascogenous hyphae, sometimes by the hook method, or 

 in chains by the transformation of successive dicaryon cells of the hypha 

 into asci. 



Conidial formation is frequently catenulate, with the apical cell the 

 oldest, as in the Erysiphaceae. Many species occur mostly in the asexual 

 stage, only very rarely producing perithecia. This is especially true of the 

 very numerous species of Penicillium and Aspergillus which form some of 

 the commonest molds upon organic matter of every kind. The details of 

 sexual reproduction still remain to be studied for the great majority of 

 genera. Even in those cases that have been studied much still remains to 

 be learned, particularly regarding the behavior of the sexual nuclei. In 

 general a straight or coiled ascogonium and coiled antherid are produced. 

 The former may be several-celled, the terminal perhaps corresponding to 

 a trichogyne, or only one-celled. In a few cases the formation of an opening 

 has been observed between the antherid and the tip of the oogone (or of 

 the trichogyne), following which ascogenous hyphae grow out of one or 

 more of the ascogonial cells. The eminent French mycologist P. A. Dange- 

 ard (1907) has observed and figured the antherid and ascogonium in nu- 

 merous species of this order. He even figured the opening from the antherid 

 into the ascogonium or trichogyne in a few cases. He denied, however, that 

 this is a sexual process and considered that the antherid has entirely lost 

 its primary function as a male organ, perhaps functioning now as a nutri- 

 tive organ, which he therefore calls a trophogone. In the main the my- 

 cologists, apart from Dangeard's students and associates, do not agree 

 with him and look upon the antherid as a functional sexual organ, at least 

 in the majority of cases where it is present. The actual observation by 

 Schikorra (1909) and by Young (1931) of the passage of nuclei from 

 antherid to ascogonium in Monascus shows that this does occur. On the 

 other hand there are well authenticated cases where a coiled or straight 

 ascogonium is produced and no organ that can be in any way interpreted 



