Branner.] 472 [April 18, 
possible that the same number of bundles was present in the upper sec- 
tions as in the lower ones, but that being smaller, they escaped my atten- 
tion. In this connection I will refer to Mirbel’s explanation of the spindle- 
shape of the stems of Iriartea ventricosa and Acrocomia lasiopatha. Re- 
ferring to Von Mohl’s theory, as originally stated, that all bundles ended 
in the base, M. Mirbel said :* ‘Il est un fait dont sans doute M. Mohl a 
connaisance, c’est qu’il existe des Palmiers pourvus d’un stipe mince & la 
base, mince au sommet et notablement renflée dans sa partie moyenne. 
Ce stipe resemble donc a une enorme fuseau * * * * * Je demande 
a M. Moh] comment il explique cette anomalie en restant fidéle a son hy- 
pothése. Pour moi, rien de plus simple depuis que j’ai reconnu dans le 
Dattier que les filets naissent de bas en haut, de tout le pourtour interne 
du stipe, et & toutes les hauteurs, A la naissance de l’arbre fusiforme, la 
végétation est faible, les filets sont peu nombreux, et par consequent la 
stipe est gréle. A mesure que l’arbre s’éleve, la végétation devient de 
plus en plus active, le nombre des filets augmente sensiblement, le stipe 
grossit. Mais quand l’arbre a atteint une certaine épaissure la végdétation 
s’affaiblit, le nombre des filets diminue, le stipe va s’amincissant jusqu’au 
sommet,’’ 
Had M. Mirbel ever examined the trunk of one of these fusiform palms, 
or had he even read a description of their method of growth, he never 
would have tried to explain this increase in size in this manner. 
Tam not able to give at present the physiological reason for this pecu- 
liar growth, but Iam able to give some explanation of how it occurs. In 
transections these palm stems show the same number tf bundles in the 
swollen part as in the more slender parts both above and below it. When 
there is a difference, it is such as may be found in any palm having a cy- 
lindrical trunk. In the swollen part there is a great increase of cellular 
tissue, and a very slight increase in the size of a few of the fibro-vascular 
bundles. M. Mirbel represents this enlarging as taking place during the 
growth of the tree, and at the top, whereas it does not occur until the 
palm has attained almost its full growth. The young Iriartea ventricosa 
never shows this enlargement in any part of its stem, and when it does 
occur in the grown plant, it is at a considerable distance below the grow- 
ing part.} In some species of Acrocomia the swelling takes place near the 
summit, but always after the crown of leaves or phylophore has passed 
the part. In one species examined at Asuncion, in Paraguay, the trunk 
has no certain point at which it swells, but may swell out either at the 
base or the summit, or anywhere between the two parts, and there are 
many cases in which there are swellings both at the base and just below 
the fronds. Neither is the tapering of a few palms like Oreodowa oleracea 
and Muterpe oleracea to be explained by a decrease of the number of fibro- 
vascular bundles toward the top. In examining many trunks of Huterpe, 
I found the number of bundles near the base and near the top about the 
* Comptes Rendus de |’Acad, 1848, II, p. 1128, 
t Wallace’s “ Palms of the Amazon,” p. 87, 
“i? 
sl 
