142 THE JOURNAL 01' BOTANY 



fungi may be distinguished from Ascomycetes in the narrower 

 sense, as the representatives of a parallel group of transmigrant 

 algae, convergent with other inure saprophytic genera in certain 

 respects. 



II. The Cask of the Ascomycete. 



Thanks to the very complete observations of Claussen on Vyrc- 

 nema confluens^, the general framework of the life of a typical 

 holosaprophytic Ascomycete can be now presented in a clear ami 

 logical nianiier. The complications consequent on a decadent c\ tology 

 have been demonstrated in detail, and the confusion introduced by 

 previous observers has been cleared up 2 . The life-history reduces to 

 a readily intelligible and simple two-phase alternating sequence, in 

 which a sexual generation (gametophyte) exhibits phenomena, how- 

 ever decadant and autogamous, of fertilization in situ. This is 

 followed by the development of the zygote, permanently nourished 

 by the parental tissues, to an asexual phase (asco-sporophyte), not. 

 only wholly parasitic on the gametophyte, but protected and fed by 

 the latter, to the extent that it reduces to the status of practically a 

 mere asexual reproductive tract, devoted to the indefinite production 

 of uniloculor sporangia (now termed asci) each with a uniform out- 

 put of eight ascopores. This ascogenous tract presents the appear- 

 ance of a hvmenial layer, with paraphvses as nutritive ramuli of the 

 parental mycelium ranging among the ascogenous ramuli 3 . The 

 inter-relation of the ramuli of the two generations may he complex to 

 a degree ; but the somatic tissues of the asexual plant are reduci d 

 to the merest minimum of a few connecting 'ascogenous hyphae.' In 

 many larger ' fructifications ' the conjoint hymenium may he relatively 

 enormously developed ( Gyromitra, Morchella, Geoglossum, Peziza). 

 The sexual gameophyte keeps pace with the enlargement of the asco- 

 genous tract, and the production of asci may he continued indefinitely. 

 Such a two-phase cycle of alternating gametophyte and superposed 

 sporophyte — the former presenting phenomena of sexual fusion, the 

 latter of meiosis— so closely follows the life-cycle evolved by many 

 phyla of marine algae, that not only is the theoretical relation sufli- 

 ciently definite, but it is at once obvious that such a life-cycle in 

 Ascomycetes of the land must have been inherited from comparable 

 algal ancestors in response to similar conditions of marine environ- 

 ment. Since the story of the algal progression in the sea itself 

 is quite clear, and there is no suggestion as to how such identity 

 of organization could have been produced in response to a complex of 

 largely different subaerial factors. The origin of the fungus from 

 sea -weeds is more inherently probable than that of the sea-weed 

 from fungi, and invocations of the ' long arm of coincidence ' merely 

 negative scientific investigation. 



Following the ordinary interpretation of the facts, as based on 



1 Claussen (1912), Zeitschrift fur Botanik, p. 1. 



2 Guilliermond (1912), Rei Progressus, p. 511; Faull (1912), Ann. Bot. 

 p. 346. 



:i De Bary (Eng-. TYans. 1887), p. 186, for scheme of Ascobolus. Guilliermond 

 (Rei Progressus, 1912), p. 515, for Pyronema. 



