Woody Fibre of the Stems of Palms. 



59 



the course of the stem for some distance, and then turns out- 

 ward again, finally losing itself in the cortical integument. 

 In the course of their downward descent the woody bundles 

 gradually separate into threads, till at last the vascular sy- 

 stem, which for a long time formed an essential part of each 

 of them, disappears, and there is nothing left but woody tis- 

 sue. In this view of the growth of endogens, the trunk of 

 such plants must consist of a series of arcs directed from 

 above inwards, and then from within outwards ; and conse- 

 quently the woody fibres of such plants, instead of being par- 

 allel with each other, mast be interlaced in infinite intermix- 

 ture. There are, however, some difficulties in the way of this 

 theory, which we do not find adverted to by its author. If 

 MohPs view of the structure of endogens be correct, they must 

 after a time lose the power of growing, in consequence of the 

 whole of the lower part of their stems being choked up by the 

 multitude of descending woody bundles. Is this the case ? 

 The lower part of their bark, too, must be much harder, that 

 is, much more filled with woody bundles than the upper. Is 

 that the fact ? The hardness of the exterior of palm-stems 

 cannot be owing to the pressure of new matter from within 

 outwards, but to some cause analogous to the formation of 

 heart-wood in exogens. t Is there any proof that such a cause 

 is in operation ? I mention these things," continues Dr. Lind- 

 ley, " not so much from distrust of MohPs views, as from a 

 desire to see the difficulties which seem to lie in the way of 

 an ingenious theory satisfactorily removed." 



At the time of reading this I was prosecuting my botanical 

 researches on the Organ Mountains of Brazil; and having 

 ample opportunity for making observations on the subject, 

 from the great number of individuals of the palm tribe which 

 are found on this range, of all sizes, from the tall species that 

 inhabit the plains, to the dwarf ones which are met with at an 

 elevation of upwards of 5000 feet, I determined to ascertain 

 whether or not the views of Mohl, as stated by Dr. Lindley, 

 were correct. 



The first individual I examined was a large low-growing 

 species, called by the Brazilians Coqueiro. The stem mea- 

 sured feet in circumference, and the leaves were inserted 

 at the distance of 3 inches from each other. Having caused 

 a longitudinal section of the stem to be made, both through 

 the portion destitute of leaves, and that to which the leaves 

 were attached, the bundles of woody fibre were distinctly seen 

 passing from the scars and the bottoms of the leaves down- 

 wards and inwards to the middle of the stem at an angle of 

 18°. The individual fibres being large in this species, I was 



