326 BOTANICAL GAZETTE [October 



at an interval. They do not ordinarily separate into the usual 

 bands, which is doubtless the reason their presence has not been 

 heretofore recognized in the case of abortive Equisetum spores. 

 Examination has been made of a number of sporangia of Catamites, 

 and here, as in the living Equisetum, when uncontaminated by 

 species crossing, the spores are perfect, although without the elaters, 

 which appear likewise to have been absent in the mesozoic Neo- 

 calamites. 



The ferns may next be considered, and for the purpose of 

 the present investigation they may be divided into the Poly- 

 podiaceae and the remaining ferns. Taking the latter first, no 

 evidence of hybridization in the recognized older groups of ferns 

 has been found in this connection. Fig. 5 illustrates in section 

 a sporangium of Angiopteris evecta. The spores are obviously 

 all perfect. Examination of the genus M arattia has led to similar 

 results. Other representatives of the Marattiaceae were not 

 available. The Ophioglossaceae, as represented by the three 

 genera Ophioglossum, Botrychium, and H elmintho stachy s , were 

 studied and no evidence of abortive spores found in the sporangia. 

 Representatives of the Gleicheniaceae and Schizaeaceae yielded 

 similar results. Osmunda regalis, O. cinnamomea, and O. Clay- 

 toniana have strikingly perfect spores. Todea Barbara showed 

 similar conditions. Hymenophyllaceae, as represented by Hyme- 

 nophyllum and Trichomanes, and the Cyathaceae by Alsophila 



results. Of the heterosporous 

 e available, and these showed 



same 



Marsilia 



uniform 



uniform 



umerous cases of hybridism among the Polypodiac 



The 



accompanied by greater or less spore abortion, are known, 

 writer has personally examined only one hybrid fern of this group, 

 namely the so-called Adiantum hybridum of gardeners. The spores 

 here are apparently completely abortive, at any rate in greenhouse 

 specimens. It will be unnecessary to enlarge upon the hybridism 

 of the Polypodiaceae further, because recently an admirable state- 

 ment has been published by Benedict, 2 in which he discusses 

 the subject fully. He reports 11 natural hybrids for the eastern 



2 Benedict, R. C, Bull. Torr. Bot. Club 36: 1909. 



