I>yBUN NATTJBAX UISTOBT SOCIXTr. 55 



taking those which are the commonest, and which, fortunately, also happen to 

 be the most fully worked out. These are — y&r. cristalum and Huh-var. muhifidum. 

 These both consist in a repetition of the various parts of the normal frond— this 

 is a true duplicature, not a mere modification of other organs such as we see in 

 double flowers. Every part of the aerial organs is found doubled ; some more 

 commonly than others. In simple fronds wo find it in the stipe, the rachis, and 

 the apex of the frond. In compound fronds, in addition, it is also found in the 

 pinnsB and the pinnules — in fact, it may bo found in every axis of the plant, pri- 

 mary, secondary, tertiary, &c. It is also found in the sori, though more diffi- 

 oult to demonstrate, as in some forms of Phyllitis scolopendrium ; 1 met, myself, 

 with a wild specimen of Trichomanes speciosum, which 1 now show ; when I got 

 it, almost all the thecso were in pairs. 



Perhaps it is wrong to call the organs doubled, as they are not strictly so 

 all through, but arise single, and then split into two, obeying a law of nearly 

 universal occurrence in nature, in accordance with which we find that the aber- 

 rant forms of the higher groups copy closely t|io normal type of those below 

 them ; thus, the dichotomy, which obtains in these forms, is the normal state of 

 some, at least, of the Lycopodiacese — ex.gr. Selago, and is also seen in the seed 

 lobes of some exogens. 



Some have proposed to separate into different groups the forms placed at the 

 head of those groups — i.e. where the division affects the stipe, but this appears 

 contrary to analogy. They ground their opinions chiefly on its rarity of occur- 

 rence among species, but even they allow that it is not a constant character ; 

 we will find it is rare, but not so rare as either the division of pinnule, or sori, 

 or thecte ; and if we do not make any distinction between the rachis and stipe — 

 which division, after all, is an arbitrary one — wo will find the form not so rare 

 at all — in fact, the nearer we go to the apex of the primary axis, the commoner 

 will we find this division; and it is what might be expected, the modifying 

 causes not having an opportunity to develop their action till the frond is par- 

 tially developed, for if it acted previously, we would have two fronds instead of 

 one. If we examine a simple frond, we will find this well shown, as the rarest 

 specimens are those divided deeply, and the commonest those having merely the 

 apex split, often multifidly so. The sub-variety is much commoner some years 

 than others ; the rule 1 have not yet satisfactorily established, and, therefore, I 

 shall content myself with enumerating the species, leaving it to some other 

 hand, or some other time to explain the laws. The variety cristatum, as, indeed, 

 may be said of all varieties, is uniform, much rarer, and is found in fewer .species 

 than the sub-variety. It is thus defined : — Variety, Cristatum ; constant ; stipe, 

 often bifid or multifid ; rachis, do., do ; segments rounded at edges and apices ; 

 confluent often curled and crisped; veins generally terminating in a lash of 

 branches : generally fruitful. Examples — Phyllitis scolopendrium, var. crislaluiu 

 (auc); Lomaria spicant, var. cristatum (Mei) ; Athyrium Filix F«miua, var. 

 cristatum (three forms) — Alpha, Beta, Gamma (as before), &c. All these forms 

 are allowedly fruitful. 



The variations of this form arc numerous, from the simple, curled, almost un- 

 divided apex of one form of Ph. scolopendrium, to which the name Crista galli 

 has been given, up to the extreme divisions seen in the forms of Phyll. scolopen- 

 drium, var. multijidum. The sub-variety multifidum is very extensivelv repre- 

 sented ; out of the twenty-four genera of British ferns, enumerated by Newman, 

 being recorded in all but five — viz., Adiantum {vide list at end), rseuilathy- 

 rium, Hemcstheum, Cystopteris Woodsia.* It runs through every stage, from 

 simple lobing of the apex of the frond, or of the ends of the pinna; or pinnules, 

 down to the division of the stipe itself. In some species it is very common ; in 

 others very rare. Character — Subvariety multifidum; not uniformly constant ; 

 stipe sometimes dichotomous; rachis bifid or multifid; segments, following 



# 



• Newman fljcure* « frond of WoodaU allrcnsis, which appears to be ifiii//»/<lmii.— Brit. Feni#, 

 p. 187. Second edition. 



