Branner,] 474. [April 18, 
both in connection with the structure of the plant, and in its influence 
upon the plant’s general appearance.* It varies greatly in different species, 
and may be almost wanting. In trying to split palm stems, those in 
which the spiral direction is less marked, split more readily than those in 
which it is more decided. It is not very marked in Mauritia carand, Huterpe, 
and Iriartea, while in Maximiliana and Manicaria it is a very prominent 
feature, 
It is not in the trunk alone that spiral direction is to be seen, but it is 
more or less observable in the fronds and spathes. The trunk may have 
a very decided spiral direction in its fibro-vascular bundles, which may be 
wanting in the fronds, and vice versd. Raphia tadigera (vulg. Jupaty), 
for example, hag a marked spiral direction of its bundles in the trunk, 
while the petioles of the fronds split with almost perfect evenness. Spiral 
direction in spathes is well shown in the spathe of Manicaria saccifera 
(vulg. Ubuss%), which resembles coarse cloth somewhat. 
In the petioles and midribs of some palms, modifications of spiral direc- 
tion give rise to peculiar and characteristic forms of midribs, resulting in 
changes of the leaf planes from a horizontal to a vertical position, which 
are characteristic of the species in which they occur. 
It has been noticed by those who have studied and observed palms in 
their native forests, that, after a certain amount of experience in familiari- 
zing one’s self with the general appearace of them, the common palms can 
be distinguished at almost any distance at which they are visible, if only 
the fronds can be seen. In those having pinnate fronds this is very largely 
due to the effects produced by changes in the leaf planes, which are the 
result of changes in the shapes of the midribs, which, in their turn are 
the result of the direction of the fibro-vascular bundles. In the Maaimit- 
tana regia Mart. (vulg. Inajé) and Attalea ewcelsa (vulg. Urucurg) of the 
Amazon region, and in Acurg,}+ of the upper Paraguay, the bundles in the 
midrib are turned to one side as shown in figure X, page 477. 
In No. 1 is shown a section across a midrib not far from the trunk, 
where it has the usual shape of a midrib, In No. 2, a section further out- 
ward, the bundles of the side CB (1) have moved up and gone to form an 
extension of AB, while a corresponding number from the side AC have 
taken their places on CB. The result is a figure like No. 2. No. 8 rep- 
resents a section still further out, and No, 4 is one near the tip, this direc- 
tion to one side being more marked the nearer we approach the end of the 
frond. The midrib assuming these forms, it is impossible for the frond to 
maintain its horizontal position, whereupon it changes its leaf plane from 
a horizontal to a vertical position, and droops over on its edge. It might 
be supposed that this twisting of the frond is due to some arrangement of 
the leaflets with reference to the light, but in the Maaimiliana regia 
CInajaé) the tips of the fronds are completely inverted in a great many 
*T have not studied the relation of the spiral direction of these bundles to 
the phylotaxis, but I suggest that the two are related, 
} Botanical name not known. 
