THE PALM-STEM. 43 



neglected to examine the same vascular bundle in various parts of its course, 

 so that its changes of form and structure remained unknown to him. 

 Moldenhawer states that both in the Grasses and the Palms, fibrous bundles 

 without vessels are formed beneath the rind, and believed that shortly after 

 their formation proper vessels, and subsequently the wood portion, were de- 

 posited on their inner side, and that in this way the fibrous bundles became 

 vascular bundles. I cannot confirm this account, for the transition from the 

 evascular fibrous bundle into the vascular bundle is merely one relating to 

 space, and has no reference to its development in time ; the lower part of 

 every vascular bundle remains permanently in the condition of an evascular 

 bundle of prosenchymatous cells, while its upper portion does not appear, 

 even in its earliest stage, in the form of a liber-bundle ; but even at a period 

 when it is still of a gelatinous delicacy of consistence, the rudiments of all 

 the parts which it subsequently contains may be detected in it. 



Moldenhawer further states, that in the Palms, not only has each vascular 

 bundle its proper liber, but there exists besides a general liber, lying under 

 the rind (1. c. p. 56). There is found, he says, in Phwnix and other Palms, 

 a line of separation between the wood-layer and the rind, from which those 

 fibrous bundles develope inwards, which are changed into vascular bundles, 

 but on its outside, those which contain only fibrous cells, the latter being 

 comparable to the liber of trees. A correctly observed fact certainly appears 

 to afford the ground for this opinion. I have observed already, that in many 

 Palms, especially in the Cocos-like stems, the rind becomes gradually thickened, 

 and this in an irregular manner ; that larger or smaller portions of the cel- 

 lular tissue in which the fibrous bundles are imbedded acquire thickness in 

 their walls, and form a firm, apparently dead envelope. In this change of 

 the outer parts of the fibrous layer, the newly-developing fibres cannot be 

 produced on the outside of the older ; they must, therefore, originate in the 

 interior of the fibrous layer, and the matter may thus acquire some resem- 

 blance to the formation of liber in the Dicotyledons. But a second circum- 

 stance also has to be considered, which might have contributed still more 

 readily to render Moldenhawer's opinion, that the Palms possess a general 

 liber, plausible. In those species, namely, where, as in Cocos, the outer 

 fibrous layer is very thick, in tracing their evascular fibrous bundles, it is 

 found that they do not all enter into the interior of the stem, and become 

 converted into vascular bundles, but that a portion of them pass immediately 

 into the petiole. But as those fibrous bundles are changed, like the rest, 

 into vascular bundles in the petiole, they cannot be regarded as liber-bundles 

 corresponding to the liber of the Dicotyledons. 



2. Another circumstance remains to be mentioned, occurring in many 

 Palms, and which at first sight does not appear to harmonize with the theories 

 of their growth detailed above. We find in many Palms, that their evas- 

 cular, small, fibrous bundles do not all lie between the rind and the developed 



