﻿12 MR. JOHN SCOTT ON THE TREE FERNS OF BRITISH SIKKIM. 



The development of tlie vascular bundles composing the woody framework and sur- 

 rounding the central cellular axis of the fern-stem, unlike that of the free bundles, is 

 limited to their upper extremities. In a transverse section of the apical parts of the 

 stem {vide PI. II. figs. 1 & 2) the woody bundles are arranged in a more or less regular 

 spiral manner, on an expanded, nearly horizontal sui'faco, in oval-ellipsoidal figures 

 (indicating the points of origin of the future fronds), passing towards the poriphrry in 

 the lower sections into sinuous plates. In tracing the development of this portion of 

 the stem, we find that the generation of cells has but limited radii, and that, towards the 

 periphery of the flattened apex and before its incipient parts have assumed theii* lateral 

 position on the stem, all increase is by simple expansion of the already formed cells, 

 which become from four to seven times as large. It is only by this increase (caused 

 by cell-expansion) of the bulk of the pith, remarks Hofmeister, that the net of vascular 

 bundles is lifted up by degrees and projected upon a cylinder. It is easily seen, by 

 coimtin^ the cells durinsj and after the transition of the net of vascular bundles from 

 the form of a paraboloid to that of a cylinder, that the increase in thickness of the stem 

 is not caused by any subsequent new formation of parenchymatal cells, either within the 

 pith or in the neighbourhood of or between the rudimentary vascular bundles (Higher 

 Crypt, p. 231). The vascular bundles surrounding the apertures of the incipient fronds, 



considerable increase from the numerous 



.) was 50 inches, 21 inches at 3 feet, and 



top. Again, in a second specimen the basal girth was b'2 inches, decreasing to 23 inches at 4 feet, and again some- 

 \N^hat suddenly increasing to 27 inches at 5 feet, thence cylindrical. Now in regard to the first specimen (as to all 

 those in the avenue with unhulged caudices), it had been thus far infertile, whHe in the other spadices had been 

 produced, and that where the caudex first undergoes an enlargement. The spadices are henceforward produced with 

 great regularity from every axil, the caudex increases in thickness to the point of origin of the sixth or seventh 

 epadii, where it seems to attain its normal diameter, and is continued cylindrically upwards. It thus appears to me 

 that the bulgmg of the caudex is due to the additional development of woody bundles from the spadix ; and I am 

 disposed to attribute such sudden enlargement as those of Martea ventricosa to periods when every axil gives origin 

 to a strong and vigorous spadix, and, on the other hand, the decrease to their frequent abortion. I have further to 

 romark that gouty stems have been observed only amongst the Arecinese, and confined to species with markedly 

 developed internodes, long sheathing fronds, and almost stem-encircling footstalks of spadices. In the other tribes 

 (Borassinca), Coryphineae, and Cocoine*) the Hgulae are short, the petiole at once passes off, at a less or more acute 



peculiarit 



Palms '). 



(vide 



with centrifugal inflorescences and monocarpic 



inflorescence the caudex is cylindrical thronshout. and so also 



m rcv^ewmg my UtUe acquaintan6e with palms, I can recall no reallv disproving facts 



peilllsotTnor 'T T r"' ™' «— i-tions to some of our monthly botanical and horticultural 



:; t : r Z^r:T!f:rrif_ ^^!- '^^. - ^he production of an audible report in the bursting 



mistake 



any report when bursting 



permitted 



Without 



and other Arecineae, the anthers do not reach maturity 



turther, that in those cases in which I have attended to it, Cocos, Oreodoxa 



ipadix 



m 



splitting up of the interior 

 days. The disarticulation 



