1884.] 461 {Branner. 
In 1839 the French Academy of Sciences sent out one of its members, 
M. C. F. B. Mirbel, to Africa for the purpose of investigating the structure 
and manner of development of the date palm, and in 1843 the results ot 
Mirbel’s work were given to the Academy.* The following year Mirbel 
contributed a paper on the structure of Dracena australis, in which he also 
referred to the question of palm structure.| Contributions to the subject 
were made by Lestiboudoist in 1840, and by Unger§ in the same year. 
In 1845 Dr, C. F. P. Von Martius gave a statement of his theories upon 
the subject. Sachs, in his text-book4 refers to Nigeli,** and Millar- 
det** as authorities upon the direction of the fibro-vascular bundles, but 
there is nothing in his own explanations to lead one to suppose that these 
writers differed materially from Von Mohl. 
These are the names of the principal contributors to the literature, and 
since Von Mohl published his appendix in reply to Mirbel and Meneghini 
in 1845, it will be seen that little or nothing has been done in the way of 
original investigation. |+ 
I will now briefly restate the theories held by the principal investigators 
in regard to the more important characters of palm structure. 
First, we have the theory of Desfontaines, Daubenton and de Candolle, 
which prevailed up to 1824, and which has scarcely yet been completely 
eradicated from text-books on botany .{{ This was the theory of endogenous 
or inward growth. It held that the inner fibro-vascular bundles in a palm 
trunk ran to the new fronds, and the outer ones to the old. This theory 
was probably largely due to the fact, that in a transection of a palm trunk 
the outer bundles are hard and bony, while the inner ones are tender, and 
generally of a lighter color. Considering the state of botanical knowledge 
at the time this theory originated, it was perhaps a natural conclusion to 
draw from so limited an investigation of the subject. A hemisection of a 
palm trunk, as they understood it, would be represented diagrammatically 
by fig. I., and a transection by fig. II. Fig. II. has the fibro-vascular 
bundles displayed just as we find them in fact, the softer and lighter-col- 
ored ones through the centre, aud the hard bony ones next the periphery. 
This crowded condition of the outer bundles was supposed to be the result 
of the growth of the new bundles at the top of the trunk, which pressed 
*Comptes Rendus de 1l’Acad., 1848, Vol. I., p. 1218. 
+t Comptes Rendus de l’Acad., 1844, Vol, II... p. 689. 
+‘ Etudes sur lV Anatomie et le Phystologie des Végétaux.”’ 
2" Ueber den Bau und das Wachstum des Dicotyledonstammes,”’ 1840, p. 85. 
| Comptes Rendus de l’Acad., 1845, Vol. I., p. 1033. 
q{ Oxford ed., 1875, p. 552. 
*k'V.. literature at end. 
tt Dr. Gray refers (Text-Book, 6th ed., 1879, p. 71, foot note) to a memoir of recent 
date by Guilland: “ Recherches sur l’Anatomie Comparée et Je Developpement 
des Tissus de la Tige dans les Monocotyledones.” Ann, Sci. Nat., Ser. 6, V., 1-176, 
1877. I have not seen this work, 
tt Dr, Gray says that the word “endogenous” is still retained for the purpose 
of indicating a peculiar stem structure, 
