APOGAMOUS FERNS. EVOLUTION OF THE SEPARATE SPECIES 



in cultivation for many years in Europe and America, both in botanic gardens and 

 as ornamental plants of commerce. 



Owing to the rather wide discrepancy between my results and those of Miss Allen 

 (1914) with regard to the chromosome numbers, it was necessary to examine a wide 

 sample of the various species with rather pedantic attention, since a superficial com- 

 parison with Pteris cretica might easily have led to erroneous conclusions. The material 

 available to me was as follows : 



(i) Horticultural plants oi Cyrtomium falcatum, grown for the market in the nurseries 

 of Messrs Clibran of Altrincham, Cheshire. 



(2) C. falcatum var. Rockfordii Hort. in the Royal Botanic Gardens, Kew. 



Fig. 180. Q'r/omzMm For/wnf 2 J. Sm., part of a dried cultivated frond. Natural size. 



(3) C. falcatum var. Rockfordii Hort., raised from spores obtained from the Botanic 

 Garden, Wisconsin, U.S.A., and thought to be identical with Miss Allen's material. 



(4) C. Fortunei of unknown origin, long established at Manchester University Experi- 

 mental Ground. 



(5) C. Fortunei, wild from the neighbourhood of Pekin, raised from spores sent by 

 Dr C. Ching. 



(6) C. caryotideum, wild from Uganda, conveyed alive in 1938 to Kew, together with 

 the Pteris cretica previously referred to, but, like that species, subsequently lost owing to 

 enemy action during the war. 



From this rather extensive range of specimens the greatest scientific interest naturally 

 attaches to the wild specimens (numbers (5) and (6)) and to the Wisconsin material 

 (number (3)). None of these was, however, obtained until the work was far advanced, 

 and in the general account already given in Chapter 10, numbers (i) and (4) were 

 principally quoted. Enough has been seen of the others, however, to make it quite 

 certain that they are not different in any way which can be detected cytologically. 



Evidence on the chromosome numbers of the three species of Cyrtomium is contained 

 in Figs. 1 81-184. In sections (Figs. 181, 182), only approximate counts can be made 

 which, in each of the three cells figured, place the number as 'not less than 119 nor 

 more than 123'. The cell of Fig. 181 a and 182 a, it should perhaps be pointed out, is 

 from Wisconsin. Only with squashes can greater precision be reached, and in each of 



178 



