8 



become necessary to ignore all, or nearly all, such varieties 

 as present defects in make or inconstancy of type in the 

 form of partial reversion, giving practically almost exclusive 

 preference to those which persistently maintain that 

 symmetry of form and make which constitutes their charm 

 from the fancier's point of view. The constantly irregular 

 forms indeed, in which no two fronds are alike, may 

 biologically be even more interesting than the regular ones, 

 suggesting as they do a continuous changing of mind, as it 

 were, on the part of the formative cells which normally 

 proceed on regular lines, repeating one and the same plan 

 over and over again. To take one of our commonest 

 examples of a fern of inconstant character but which is yet 

 so good and so marked as to be indispensable to every 

 collection : — 



Polypodium vulgave vav. comubiense (elegantissimum) is 

 one of the most marked examples of this eccentric type. 

 Found as a wild plant in Cornwall, it was seen that it 

 bore fronds of three distinct types, viz. the normal once 

 divided or pinnate one, a somewhat slenderly divided bi- 

 pinnate one, and a much more slenderly dissected or even 

 tripinnate one, of which last selected specimens have been 

 named " trichomanoides," owing to a marked resemblance 

 to Trichomaues vadicans, the beautiful native Filmy fern. 

 For many decades this fern has been propagated, not only 

 by division but also by spores, but this peculiarity of 

 partial reversion has never failed to appear, and even 

 asserts itself when a successful cross has been effected with 

 exotic ferns of the same genus, or different varieties of 

 native origin, e.g. P. Schneidevianum, P. glaucum + P. vulg. 

 com. and P. vulg. com. + bifido-cvistatum. Not content, 

 however, with producing fronds of the three types named, 

 it carries its eccentricity still further by change of plan 

 even within the limits of one frond or part of a frond, one 

 and the same example shewing normal, coarse and fine 



