Branner,} 462 (April 18, 
them out, and packed them closely together. This was also supposed to 
account for the even size of palm trunks. 
The theory of Von Mohl, based upon careful study, completely over- 
threw the theory of Desfontaines. His investigations showed too that the 
structure of the palm trunk was no such simple matter as had been sup- 
posed. The leading features of Von Mohl’s theory are as follows : Dissect- 
ing out a fibro-vascular bundle from the base of a frond, it curves in to the 
centre of the stem, and downwards, and after a short course through the 
centre of the trunk gradually approaches the periphery, and then runs 
down into the base. Later Von Mohl modified this statement, recognizing 
the fact that his investigations had been made upon too young specimens, 
and that in a full grown stem the bundles did not reach the base * He 
then concluded that their lower extremities ended blindly on the periph- 
ery, and that at their upper ends they grew into the phylophore.} He 
observed their difference of structure in different parts, their varying size, 
their hardening, colosing, the slight growth in size of the bundles blend- 
ing, and, after it was called to his mind by Meneghini, recognized their 
spiral direction (though he attached no importance to itt), and that the 
course of the fibro-vascular bundles was the same in all palms. 
Meneghini laid stress upon the oblique course of the bundles, and ex- 
plained it as a mechanical result of unequal growth of stem and frond scars. 
He supposed the trunk to outgrow the leaf so much that the base of the 
frond was thrown out of its former relation to the other fronds, and that 
the bundles were thus drawn to one side, causing this obliquity in their 
direction. The occurrence of fronds at the same angle to each other on 
the stem was accounted for in the following manner: In the apex, as he 
believed, the fronds were arranged in a helix, which, in the course of 
growth, became a spiral line upon the stem, the fronds all having been 
drawn aside equally. He also advanced a theory of the creation of the 
fibro-vascular bundles by currents of sap in the phylophore, and thought 
they were to ‘‘be regarded as descending from the nascent leaf in the 
centre of the bud.’’ § / 
*Duchartre, in his  fléments de Botanique,” p.179, gives Von Mohl’s theory 
in its original form, and in a figure represents the fibro-vascular bundles as 
all running into the base, 
7 Tnere has been no little misunderstanding of Von Mohl’s theory and deserip- 
tions, Mirbel did not know whether he meant that the bundles grew down- 
wards from the bases of the fronds (Comptes Rendus, 1843, p. 1218, et seq.). In 
Stating Von Mohl’s theory, he says that “selon M, Mohl, les filets * * * * % 
partent des feuilles,’’ and a little further on he declares that he does not know 
what Von Mohl means by saying that “les filets partent des feuilles et descend- 
ent vers la base.”’ : 
Duchartre in his “Kléments de Botanique,” p. 177, in explaining Von Mohl’s 
theory, says of a filbro-vascular bundle: ‘Il descend verticalement sur une cer. 
taine longueur,”’ 
}Duchartre has eredited Von Mohl with the discovery of the spiral direction of 
the bundles (“fléments de Botanique,’’ p. 177), but Von Mohl confesses 
that he laid no stress upon it, leaving us to infer that he had observed it. Ray 
Society, 1849, p, 52, third line from bottom, 
? Ray Society, 184), p. 90. 
