258 MORPHOLOGY. 



entirely oppose from my own observations. Hitherto I have never had 

 an opportunity of investigating living Palms, or more than small frag- 

 ments of dead ones. But from what I saw I believe I may venture to 

 conclude that the stem of Palms does not essentially deviate in such a 

 way from those of other Monocotyledons, that one may not transfer to 

 the Palms, in the main points, the laws of structure found there. Now, 

 so far as I know, such a process of growth does not occur in any Mono- 

 cotyledonous plant. According to my observations the newly produced 

 vascular bundles merely grow continuously upward. In advancing the 

 distinction of limited and unlimited bundles Martius follows me, but. in 

 my opinion, he has not conceived nearly clearly enough the distinction 

 between developed and undeveloped internodes, and in particular he has 

 not formed a clear conception of the peculiarities of the stem with un- 

 developed internodes, and the conditions of structure resulting there- 

 from. Moreover, he has left the meaning of the term onward growth 

 (Fortwachsen) of a vascular bundle equivocal. If it means that the 

 already existing elongated cells become transformed into vascular bundles, 

 it describes no peculiar process of growth, the vascular bundles were 

 already to be distinguished in their elementary condition ; but if it means 

 that the cells themselves, of which the vascular bundles are composed, 

 are produced subsequently, originating above first and proceeding down- 

 ward, this is, I believe, erroneous. It is necessary to bear in mind the 

 essential distinction between Monocotyledonous axes with and without a 

 cambium circle, in order to understand these structures. Where no 

 cambium exists there are no other new cells formed besides those in the 

 point of the bud. But where there is cambium, all development, and so 

 also the development of new vascular bundles in the stem, proceeds up- 

 wards and outwards, never, so far a I have been able to observe, down- 

 wards or toward the interior. The lowest and innermost cells are always 

 the oldest, never the upper or outer (of course excluding the bark, to 

 which alone an endogenous growth can be ascribed). I must therefore 

 distinctly assert, that in the Palms, as in all Monocotyledons, the lower 

 end of an older vascular bundle never reaches down into an internode 

 lower than that in which the lower end of its first rudiment originated. 



e. Review of Axial Structures and Terminology. 



130. The following distinctions appear to me to be of impor- 

 tance from the points of view treated in the foregoing paragraphs. 



1. Duration. 



A. Annual. Stem (caulis). 

 Internodes (internodia). 



a. Only existing in the beginning of the period of vegetation, 



fugacious (internodia funacid). 



b. Enduring the whole period (int. annua). 



c. Only existing in the latter part of the period of vegetation 



(int. serotina). 



B. Perennial. Trunk (truncus). 



