182 Mr. A. Henfrey on some Points in the Structure 
stems, of which I shall have presently to speak ; before passing 
to these, however, I must refer to the controversies which exist 
as to the course of development, in time, of the different portions 
of the fibro- vascular bundles. Von Mohl offers, I believe, no 
opinion on this point ; Schleiden states that their development 
commences below and extends upwards into the leaf, in which 
opinion he is borne out by the statements of several authors, 
particularly Mirbel* and Naudinf- GaudichaudJ states that 
the development begins in the centre, and that an ascending and 
a descending portion are gradually organized, one passing to the 
leaf, the other to the roots. 
My own observations are in favour of the former opinion, and 
indeed Gaudichaud^s publications are wanting in proper scientific 
completeness. His statements are much too dogmatic, and his 
figures have too much of the character of diagrams, to be re- 
ceived as direct evidence in a case where such complex structures 
are in question. 
In the very youngest part of the bud the nascent leaf is 
wholly cellular; the cells have generally a spherical form, like 
those of the other organs and of the conical summit of the stem ; 
the whole are clothed by a delicate epithelium. But in the sub- 
stance of the stem and nascent leaves are to be remarked certain 
regions, where the cells, in the earliest condition I have seen 
them, have a peculiar appearance, being elongated and arranged 
in parallel rows (PI. X. hg. 1 «, «) ; in the centre of these bun- 
dles of elongated cells first appear the vessels, which are at first 
unreliable spiral vessels ; these regions are in fact the nascent 
fibro- vascular bundles. These fibro- vaseular bundles appeared 
to me to be always younger and less perfect as they approached 
the apex, or punctum vegetationis. The further development of 
these elements into the ducts and woody structures found in full- 
grown bundles I have not systematically followed, as I was more 
particularly anxious to attain a clear view of their anatomical 
relation to each other and to the roots. 
The condition of the relations of the bundles above indicated is 
the same as that which exists in most bulbs, and is the form which 
gives the type characterized by Schleiden as consisting of a stem 
where the internodial portions are little or not at all developed. 
I believe that the stem of a solid Palm has essentially the same 
relative arrangement of the parts. The other type is found in 
some Palms and in the annual stems of Grasses ; this is charac- 
terized by the development of the internodes. 
In regard to the flowering- stem of the first form we have two 
modifications to discriminate, depending on the position of the 
* Ann. des Sc. Nat. 2 ser. xx. 6. f If^id. 3 ser. i. 1G2. 
X Keclicrclies gen. sur rOvgauograpliie, &c. Paris, 1811. 
