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1903] OOGENESIS IN SAPROLEGNIA 33 1 



Phycom^^cetes (Mucorales, Saprolegniales, and Peronosporales). 

 Perhaps the complex conditions of such highly specialized 

 groups as the Erys'pheae, lichens, and Laboulbeniaceae may be 

 related to the peculiar activities and possibilities of diverse 

 development in this interesting sexual cell, the coenogamete. 

 Sphaerotheca may readily stand as the last step in a process of 

 nuclear reduction. Pyronema certainly exhibits the tendency to 

 utilize superfluous nuclei and protoplasm in developing that 

 advantageous structure, the conjugating tube. And possibly 

 such tendencies might result in the production of the elaborate 

 I trichogynes of the lichens and Laboulbeniaceae, and in the latter 



group the structure that resembles the procarp of the red algae. 



PHYLOGENY OF THE PHYCOMYCETES AND ASCOMYCETES. 



The reader has probably already noted that some standpoints 

 have been taken at variance with the generally accepted ideas 

 of relationship among the Phycomycetes and Ascomycetes, and 

 of these groups to an algal ancestry. A protest is sure to be 

 offered against the disregard of certain Phycomycetes and algae 

 'in the attempt to derive the Mucorales, Saprolegniales, and 

 Peronosporales from an ancestry with coenogametes. 



There are some Phycomycetes that are much closer to the algae 

 than any of the groups mentioned above. Monoblepharis and 

 Myrioblepharis (Thaxter, 1895) exhibit sexual organs, zoospores, 

 and vegetative structure with striking resemblances in various 

 particulars to such algae as Vaucheria, Oedogonium, and Sphae- 

 roplea. The homologies can hardly be questioned and will not 

 be elaborated here. These fungi, and possibly some of the 

 Leptomitaceae, seem to be close to heterogamous (oosporic) 

 algae and may well have come from that region of the Thallo- 

 phytes. The family Leptomitaceae includes some very remark- 

 ably types which have been well described by Thaxter (1896). 

 Their position must remain somewhat uncertain until we know 

 the nuclear structure of the sexual organs, but the general mor- 

 phology of some forms indicates a relationship to the Perono- 

 sporales. Araiospora (Thaxter, 1896) is likely to prove 

 especially interesting as illustrating an activity of the periplasm 

 in forming a cellular envelope around the oospore, that is not 



