CHAPTER V. COMPARATIVE REVIEW. ASCOMYCETES. 235 



spermatia which must be supposed to be abjointed portions of such branches, are 

 in function male sexual organs, and that the archicarps are female sexual organs, and 

 that the Fungi which produce them possess the power of sexual propagation. 



This statement is not admissible in the case of all the other forms furnished 

 with homologous members. Resting on what we know, we may suspect that 

 in Polystigma the trichogyne and spermatia behave in the same way as in Collema, 

 but we have no proof of the necessary material union. In Gymnoascus and the Ery- 

 sipheae, especially Podosphaera, the two organs appear with the same constancy, 

 one might say with the same morphological necessity, as in Pyronema, and the 

 possibility of a material union of the protoplasmic bodies is not excluded by the 

 known facts. The antheridium, it is true, always remains separated from the archi- 

 carp by a membrane which, as far as we can see, is not perforated, but it 

 is closely attached to it, and dissolved or very finely comminuted substance may 

 pass through the membrane, as must be assumed in the case of the fertilisation of 

 Angiosperms. But after all nothing is proved about the matter; the constant 

 contact of the antheridial branch proves nothing ; the envelope is constantly in the 

 same position; we cannot get beyond probabilities and possibilities. Beneath the 

 level of probability we arrive at last at species like Melanospora parasitica and 

 Ascobolus, which needs revision however in this respect, with a beautifully developed 

 carpogonium, but with the attachment of the antheridium not constantly or certainly 

 observed. The conclusion on the whole is, that some of the forms in question have 

 sexual organs which can be shown to fulfil their functions, others have organs 

 perfectly homologous with the first, but with the sexual function not certainly 

 ascertained or certainly wanting. 



We have secondly to enquire after the homologies of the Ascomycetes, in which 

 there is no distinct archicarp, as far as we at present know, when the sporocarp 

 begins to appear. We will consider first the extreme cases, Pleospora and Claviceps. 

 Here the question is, are the parts in these species to be considered as really homo- 

 logous with those of the same name in the other series which has archicarps, or only 

 as very similar to them in form and function ; or, expressed in terms of the phylogeny, 

 do these Ascomycetes belong to a single series of forms descended from the same 

 stock, or to at least two series descended from different stocks only with analogous 

 ultimate construction ? We can only advance probable arguments in deciding between 

 these alternatives, but these are against the second of the two and in favour of the 

 unity of the Ascomycetes. First of all the difference alleged is the only one, while 

 they agree together in all other points of importance to a degree which is else- 

 where found only in allied forms, and not in those which are merely analogously 

 developed. Secondly, no other close affinity can be found for the Ascomycetes which 

 have no archicarps than that with the others ; and they must have some relation of 

 the kind, some connection with other forms. Thirdly, the extremes are evidently 

 connected together by intermediate forms. The first of such forms is to be found in 

 Melanospora parasitica with its beautifully developed carpogonium but inconspicuous or 

 absent antheridium ; other like phenomena appear to occur occasionally * in the series 

 jof the Sordarieae, and these therefore claim the attention of observers. Sclerotinia also 



1 See also Zopf in Sitzgsber. d. Brandenb. hot. Ver. 1877. 



