GENERAL SUMMARY OF THE PRINCIPAL NEW FACTS RECORDED 



Asplenium germanicum auct.non Weiss (Chapter 6). 



Polystichum illyricum Hahne (Chapter 9). 



Woodsia ilvensis (L.) R.Br, x W. alpina (Bokon) Gray (Chapter 9). 



Equisetum trachyodpn A.VtY. (Chapter 13). 



E. Moorei Newman (Chapter 13). 



E. litorale Kuhlw. (Chapter 13). 



(6) The following hybrids have been synthesized and their cytology and structure 

 described: 



Dryopteris Filix-mas (L.) Schott s.str. x D. abbreviata (Lam. & DC.) Newm. 



(Chapter 4). 

 Polystichum aculeatum (L.) Roth x P. angulare Presl (Chapter 9). 



(7) Lycopodium Selago L. is shown to be problematical and to require further work to 

 determine its chromosome number and to reconcile the evidence of extensive failure of 

 pairing at meiosis, suggestive of a hybrid origin, with the known fact of the occasional 

 occurrence of gametophytes. (Chapter 15.) 



(8) The highest chromosome number yet recorded in the plant kingdom has been en- 

 countered in Ophioglossum vulgatum L., where n = 250-260. (Chapter 16.) 



(9) A haploid sporophyte has been obtained by induced apogamy in Scolopendrium 

 vulgare Sm. (Chapter 12). Other suspected cases of haploids have been shown to admit 

 of alternative explanations. (Chapters 1 1 and 12.) 



(10) A photographic demonstration of the cytology of sporangial development in 

 apogamous ferns has been given. (Chapters 10 and 11.) 



(11) Multivalent chromosome pairing has been demonstrated for the first time in the 

 Pteridophyta in the autopolyploid series of Osmunda which is described. (Chapter 3.) 



(12) Spiral structure of chromosomes has been demonstrated in Equisetum, Psilotum 

 (rather imperfectly), Hymenophyllum, Todea and Leptopteris, in addition to Osmunda in 

 which it was already known. 



(13) Some new or little-known biological observations are quoted on the cultural 

 needs of Ophioglossum lusitanicum L. and Isoetes hystrix Durieu (Chapters 15 and 16); on 

 the prothalHal structure oUsoetes hystrix, Ophioglossum vulgatum and Psilotum (Chapters 14, 

 15 and 16), and on the coning habits of the European species o^ Equisetum (Chapter 13). 



(14) Statistical comparisons are made between the frequencies of polyploidy in the 

 fern floras of Britain and Madeira and of both with the Flowering Plant floras of 

 N.W. Europe. From this, conclusions are drawn as to the cause and meaning of 

 polyploidy (Chapter 17). 



(15) Other evolutionary conclusions are discussed in Chapter 17. 



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