LABOULBENIALES 391 



know. Besides, both have imperfect forms, as still happens in dioecious Ascomycetes. 

 The perithecia arose in a way such as still occurs in relatives of the Plectascales, 

 the Sphaeriales (Sordaria and Teichospora) by division of a single mother cell. The 

 male sexual organs, as happened in the Plactascales, Pezizales, etc., degenerated 

 so that in the male individual only the imperfect stage remains. In this manner, 

 the numerous sterile (imperfect) mycelia of the Ascomycetes might be explained 

 simultaneously. They are male mycelia without sexual organs. In compensa- 

 tion for lost gametangial copulation there followed a deuterogamous fertiliza- 

 tion of ascogonia by conidia. In the dioecious forms, chiefly, the conidia of the male 

 individual may have served as these secondary spermatia and have apparently 

 secondarily retained some sexual tendencies or affinities. Apparently the conidia of 

 the female individuals can fulfil the sexual function as the example of Stigmatomyces 

 Sarcophagae allows one to assume. 



Thus in the Laboulbeniales, as in the Pezizales and in the Discomycetous lichens, 

 the function of the conidia as spermatia would be a secondary phenomenon, a conse- 

 quence of the degeneration of the male sexual organs. Their copulation with tricho- 

 gynes would be fundamentally the same process as copulation of oidia and hyphae in 

 the Basidiomycetes except that in the Ascomycetes the female organs are recognizable 

 as such, while in the Basidiomycetes they have disappeared like the male sexual organs, 

 so that the sexual act occurs pseudogamously between the hypha and imperfect form. 



It is clear that these suggestions do not solve the problem of the phylogenetic 

 derivation of the Laboulbeniales. We were only attempting to show that in case one 

 wishes to maintain the phylogenetic unity of the Ascomycetes, it is possible to regard 

 the Laboulbeniales as degenerate Pyrenomycetes. Many problems await explana- 

 tion. Thus in the Ascomycetes we know no other group like the Laboulbeniales, 

 which possesses a definite number of ascogenous cells with unlimited capacity for 

 division. At present such cells are known only in the Basidiomycetes. Similarly, the 

 significance of the appendages is still puzzling; the example of the Coreomyces where the 

 lower cells of all appendage cells are adapted to conidial formation, tempts one to 

 assume that the appendages were originally conodiophores which, however, like the 

 sporangiosphores of Chaetoshjlum Fresenii and Chaetocladium Brefeldii, because of 

 scanty nourishment have ceased conidial formation and have Undergone a functional 

 change to become setae. 



If, however, one is not inclined to the derivation of the Laboulbeniales and the Pezi- 

 zales from the Florideae, as was proposed sixty years ago by Sachs and more recently 

 by Vuillemin (1912), B. O. Dodge (1914) and Fink (1915), there still remain as roots 

 of the Ascomycetes two orders, the Oomycetes (Bary's school) and the Zygomycetes 

 (Bref eld's school). The derivation from the Oomycetes is based chiefly on the 

 similarity in manner of formation of eggs and ascospores and on external morphological 

 relationships between copulation tube and trichogyne. The comparison of egg and 

 ascospore presupposes a homologization of oogonia with asci; this is untenable, how- 

 ever, because of the different positions of these organs in the change of nuclear phase. 

 Besides, Wettstein (1921) points out that the Oomycetes known at present have a 

 cellulose membrane but the Ascomycetes, like the Basiomycetes and Zygomycetes, 

 have a chitinous wall. 



The above speculations are partially open to criticism on the ground of insufficient 

 knowledge of variation which results from a study of a large series of specimens of 

 a group. Thus, it may be pointed out that the discussion of the transition from endo- 

 to ectoparasitism is of no phylogenetic significance, since this habit has arisen inde- 

 pendently in unrelated groups. Biologically, it is an adaptation to the host, haustorial 

 development being usually related to the softness of the body of the insect, and to the 

 nature of the integument. Ordinarily the foot penetrates the integument over a pore 

 canal and the organism is able to get sufficient nourishment from the blood of the 



