=e 
ae 
7 
1884, ] 473 [Branner. 
same, but I always found, where there was a decided tapering of the trunk 
from base to summit, that there was a difference in the size of the bundles, 
slight to be sure, but quite as marked as the difference in size of the two 
parts of the trunk. This difference in the size both of the trunk and of 
the bundles is more noticeable in Qreodoawa oleracea, or the royal palm, 
than in any other palm which came under my observation. 
I have spoken of the branching of the fibro-vascular bundles and their 
return always to a frond base, as if their course was on the same side of 
the trunk and in a vertical line. Neither is the case. It often happens 
that instead of returning to a frond base upon its own side, the bundle 
crosses through the whole stem and connects with one on the side oppo- 
site.* Mirbel claimed that in the date palm, the bundles all crossed from 
one side to the other. I shall not say this is not true of the date palm, 
for [am well aware that there is a great variation of structure among 
palms, but I have never found this crossing from side to side to be the 
rule, although it often occurs, and is more marked in some palms than in 
others, 
In addition to this occasional crossing the stem, the bundles have a 
winding direction, so that their course is not directly vertical, but spiral, 
both right and left, about the stem, part of them going to one side and 
part to the other, From base to summit then, a bundle may be said to 
have a spiral plane within which it grows, and whether it returns to the 
surface upon the side on which it originated or upon the opposite side, it 
is always in this spiral plane. Meneghini tried to explain this spiral direc- 
tion of the bundles as a mechanical result of the growth of the tree where- 
by the relative sizes of the trunk and frond bases became changed. He 
supposed the fronds upon the apex to be arranged in a helix, and that as 
the tree grew this helix developed into a spiral line upon the stem. He 
believed the leaf bases to be always of the same size, both upon the grow- 
ing cone and upon the stem. The growth of the trunk then, and the un- 
changed size of the bases of the fronds necessitated a drawing of the 
bundles toward these bases, which resulted in the spiral direction. 
But I have observed that the relative position of the fronds is always 
the same, a matter which Von Mohl was in doubt about. The spiral 
direction of the bundles is in no way a mechanical one, but exists alike in 
stem and phylophore as I have often observed, and until some better 
reason can be assigned for it, must be considered as organic. 
The existence of a palm having its fronds arranged in one plane} would 
of itself be sufficient to upset Meneghini’s theory of the helix and spiral. 
This spiral direction of the fibro-vascular bundles is an important one, 
* Dr. Von Martius believed this to be the case, as will be seen in the Comptes 
Rendus de l’Acad., 1845, Vol. I, p. 1038, 
ft About Paré and the mouth of the Amazon a distichous palm is very com- 
mon, It is popularly known as the bacedba, and is tne Ginocarpus baccaba 
of Martius, Urania speciosa and U. amazonica are other distichous monocot. 
yledons, 
PROC. AMER. PHILOS. 800. xxt. 115. 8a. PRINTED MAY 29, 1884. 
