﻿,MR. JOHN SCOTT ON THE TREE FERNS OF BRITISH SIKKIM. 19 



trifurcation, the dwarfed (and wliat I was disposed to regard as the original) axial bud 

 occupying an apparently median though somewhat deflected position on the same plane 

 as the other two. The dissections, however, show that this is not the case, but that it is 

 simply the result of a bifurcation repeated on one of the axes, the bifurcation of the 

 terminal bud giving rise to shoots A and B, the latter undergoing a secondary furca- 

 tion, and giving rise to G, a few lines higher. The points of origin of the different forks 

 thus differing so slightly in the transverse sectional drawing, we find all presenting much 

 the appearance of having had a consentaneous origin. With reference to Hof master's 

 mode of distinguishing buds from normal ramifications, the difficulty is here exemplified. 

 In the primary forks we find the shoot A, from the more vigorous development of the 

 shoot B, laterally displaced and suddenly contracted at the base, presenting very slightly 

 more continuity with the main axis than do many lateral buds, which readily shows the 

 difficulty there must be in cases of more complete suppression (of such terminal shoots) 

 to distinguish them from ordinary lateral buds. 



This we will here attempt to exemplify more fully by reference to the very viviparous 

 A. comosa, a specimen of which is represented in Plate II. We there find that nearly 

 all the young buds originate around the exterior base of the stipes, and always below the 

 diaphragm of the latter. The stems of these adventitious buds are ultimately continuous 

 T^ith the woody base of the stipes, and, as a matter of course, with the interior woody 

 structure of the stem, as shown in the transverse section of ^. comosa, Plate II., fig. 4. 

 .In structure these are very different from those originating on the other parts of the 

 stem, m w^hich the woody parts are reduced to a slender root-like process, connected 

 with the external woody laminae of the stem, and always readily distinguishable as adven- 

 titious buds. These, I suspect, are the normal adventitious buds of Hofmeister, while the 

 others seem to me to hold an intermediate position between those and the lateral buds of 

 that author. Though it is thus by no means so easy to distinguish the different forms of 

 adventitious buds from bifurcations of the apex, there can be no question, as Hofmeister 

 has rightly insisted, that the ramification of the vascular cryptogams has only an 

 analogical relation to the axillary position of the branches of ph^nogams. The buds 

 of Trichomanes, which Mettenius considered truly axillary, are much too variable to 

 afford any satisfactory conclusion, as are also those of the DavalUce, as admitted by 

 Mettenius. 



The Stipal ioc?/?i.— Around the external base of the frond of all tree ferns (vide 

 Plate VIII.) we I find a series of irregularly shaped perforations, filled, in the mature 

 state, with a brown, glossy, carbonaceous powder. The various appearances they present 

 are shown under the respective species ; but it is difficult to conjecture what purpose they 

 serve in the economy of the plant. Though placed directly in the bud-region, they in 

 no case give origin to these ; nor do rootlets ever protrude from them. They are found 

 in the earliest stages of the frond's development, and are then filled with a green cellular 

 tissue ; and as they are on the same plane as the fleshy parenchyma of the frond, I have 

 been frequently disposed to consider them the aborted tracings, corresponding to the 

 costse, of a strongly auricled-frond-bearing progenitor. This view seems to me sup- 

 ported by the fact that similar i^erforations are continued up the sides of the frond, 



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