232 COMPARATIVE MORPHOLOGY OF FUNGI 



Thus also, the ascogonium would be designated as a rudimentary tricho- 

 gyne. P. rubrum, thus, would be considered a form in which spermatial 

 fertilization was lost and replaced by a parthenogamous sexual act. 



It must be emphasized, however, that among these proposed ideas 

 there is no place for spermatial fertilization. The numerous examples 

 of development of Hypocraeales and Sphaeriales are adapted without 

 exception and with astonishing uniformity to the scheme of the Plecta- 

 scales, hence the Pyrenomycetes undoubtedly have arisen from the 

 Plectascales type. Thus there is no phylogenetic necessity for assuming 

 prehistoric spermatial fertilization and, besides, such a fertilization 

 would be practically impossible, for the pycnia (spermatogonia) develop 

 in spring or early summer and then disappear. The ascogonia which 

 they should fertilize arise months later on the same stroma; spermatial 

 fertilization, as we shall see in the Uredinales, is quite improbable. The 

 fact that we know insufficiently the conditions for the germination of 

 these pycniospores is not proof that they are functionless spermatia. 

 Brefeld, Tavel and Moller (not using single spore cultures or probably 

 even pure cultures!) have reported germination of microconidia with 

 mycelial development. 



It seems much more important for the explanation of relationships 

 of Polystigma, to refer to its saprophytic, more easily investigated relatives 

 such as Melanospora and the Aspergillaceae, whose imperfect forms do 

 not resemble these and germinate easily, hence scarcely have the signifi- 

 cance of disguised spermatia. In Melanospora parasitica, M. Zobelii, 

 etc., as in the typical Aspergillaceae, are still formed two copulation 

 branches which, at least in M. Zobelii, occasionally come into open 

 communication at the tip. In other forms, only the helical ascogonium 

 is formed, from which alone, development proceeds. Gaumann prefers 

 to consider Polystigma rubrum as a reduced form of this type in which 

 (and here is the fundamental significance) in spite of the degeneration 

 and disappearance of the antheridium, caryogamy is still necessary, 

 but leads to parthenogamy within the ascogonium. Thus the loss of the 

 original cross fertilization is compensated. Unfortunately the reduced 

 species of the Aspergillaceae and Melanospora corresponding to the 

 Polystigma type have been insufficiently investigated, hence we are 

 too uncertain whether the binucleate condition which leads to the 

 formation of ascogenous hyphae, is caused by a usual nuclear pairing 

 in any cells, or by a parthenogamy as in Polystigma. If forms which 

 belong to the last type are discovered, the interpretation of Polystigma 

 given here would be much reinforced. 



Concerning the nature of the ascogonial processes called rudimentary 

 trichogynes, we can only offer conjectures. It is possible that these 

 structures correspond to true trichogynes; but it must be emphasized 

 that this in no way involves a spermatial fertilization, for the simplest 



