﻿B MR. JOHN SCOTT ON THE TREE FERNS OF BRITISH SlKKLM. 



the frequent definite relations between the positions of the branches and fronds of the 

 main axis. Karsten and Mettenins, having regard to those poslilona! rcktions of the 

 branches and the fronds, do not consider that the ramification of ferns is in any respect 

 difi-erent from that of phsenogams, both originating in the development of lateral buds, 

 which have a definite positional relation to the appendicular organs. This opinion Mct- 

 tenius supports by the occurrence of what he considers truly axilbry buds in various 

 species of Tnchomanes,3in6. the variously posed infra- or extra-axillary buds of the Da- 

 valliecs. Under the same category Mettenius places the buds found on the stipes of 

 I'ieris aquilina and Aspid'mm Filix-mas, though these are evidently, as Uofmeister 

 remarks, " adventitious buds distinct from the true ramifications of the stems." The 

 real difference between the views, then, resolves itself into the question whether the 

 bifurcation of the caudex, and the genesis of buds at the base of the stipes, are cognate 

 phenomena, and relatively to the main axis analogous to the axillary buds of phgenogams. 

 Uofmeister replies in the negative, and supports his position by various arguments, which 



I shall subsequently notice. 

 The general structure of the caudex has been skilfully treated by Mohl {vide Martins, 



Ic. Plant. Crypt. Bras. p. 40.) ; but as there are still differences of opinion, as I have 

 above shown, on several important points, and others in which there seems to me a 

 general misconception, I have taken advantage of the opportunities afforded me in the 

 Sikkim forests to secure stems of the various species \ and the x'esult of my examinations 

 of these I now beg to submit to this Society. 



The structure of the caudex is pretty clearly illustrated in the accompanying drawings. 

 Of these I may first refer to the various transverse sections shown on Plates I., II., & III* 

 The section of Alsophila latehrosa (PL I. fig, 2), from a newly cut stem, presents a large 

 central mass of parenchyma, in which are imbedded a number of isolated fibro-vasculai 

 1) undies, with a triple series of sinuous woody laminse on its periphery, and externally 

 encased in a sort of hardened rind. In fig. 4, it will be observed that the number of the 

 large isolated woody bundles in the central cellular axis is greatly reduced, . and indeed 

 chiefly confined to the periphery, while in PL II. fig. 4 they are entirely absent. So 

 also we find variations presented in the degree of continuity of the woody laminae, each 

 loop corresponding to the origin of a frond. This character, however, unHke those of 

 the isolated woody bundles, is by no means specificaUy characteristic, but variable even 

 in the same^ individual, and largely dependent on the health of the plant, and of course 

 ()n the angular divergence of the frond. This is well shown by reference to PL IV. 

 figs. 1, 2, & 3, representing three sections of Alsoj>hUa contaminans. Pig. 1 represents 

 a section at two feet from the base, and presents only three plates arising" from \ frond- 

 aiTangement, while in fig. 2, of a reduced section at 8 feet from the base, there are five 

 distmct plates corresponding with a f angular divergence of the fronds. The section 

 from the dried stem (fig. 3) exhibits the peculiar W-lil^e lamina, as generally represented 

 m botamcal manuals, and, as in fig. 2, is characterized by a f frond-arrangement. 

 1 he additional Y-shaped lamina is simply a result of the contraction of the ceUular 



Zt. I .^^^Jf ^^^^^ ^^^^^^-^ ^ tt« line of origin of a new frond in the lamina a, 

 before a union has been effected with the adjoining lamina 6. Mohl, in his treatise 



