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XXIV. On the Anatomy of Victoria regia.~Part IL 
By Akthur Hexfrey, F.R.S., F.L.S., Professor of Botany in Kimjs College, London. 
Eeceived May 5, — Bead May 19, 1859. 
In a contribution to the Philosophical Transactions of this Society, published in 1852 
(Part II. p. 289), I gave an account of the internal anatomy of the stem or rhizome of 
Victoria regia. I then stated that I regarded the arrangement of the vascular structures 
as essentially agreeing ivith that typical in Monocotyledons, and I dhected attention to 
certain points of less importance, some of which appeared to strengthen the general 
argument in question, while others were opposed to it. Subsequently I have had an 
opportunity of studying the anatomy and development of the leaves, roots, and flowers 
of Victoria, and of observing some interesting facts which have not been clearly made 
out in any of the various memoirs which have appeared on this subject. I have also 
been led to a reconsideration of the subject of the anatomy of the stem by a criticism 
which appeared in the ‘Flora Indica’ (p. 236), the distinguished authors of which, in 
then- advocacy of the opinion that the Order Nymphaeacese is really Dicotyledonous, 
question the agreement which I have declared to exist between the structure of the 
stems of Victoria and of Monocotyledons. 
In the present paper, which may be regarded as a continuation and completion of the 
former, I shall fii’st deal with the debated question of the structure of the rhizome, and 
afterwards give an account of the development of the appendicular organs, including the 
flower, and of the phenomena presented in the germination of the seed. For the abso- 
lute determination of the question whether a stem were organized on the Monocotyle- 
donous or the Dicotyledonous type, it would be requisite first of all to define clearly what 
conditions we regard as typical in the two classes. This is no easy matter in the present 
state of our knowledge. The old terms Endogenous and Exogenous growth are founded 
on no corresponding contrast in the organization of the plants to which they refer. 
Exogenous growth is a reality, but endogenous growth is a figment of the imagination. 
The general distinctions between the stems of the two great classes of Angiospermous 
Flowering Plants depend upon a different mode of arrangement of the fibro-vascular 
bundles, and, usually, in addition to this, upon a different mode of arrangement of the 
elementary organs in the fibro-vascular bundles. These are the only essential differences ; 
the formation of annual rings is by no means a constant phenomenon in perennial Dico- 
tyledons. It offers, however, a negative character for the Monocotyledons, since, from the 
construction and arrangement of their fibro-vascular bundles, they cannot produce annual 
(or periodical) rings of the same kind as those of the Dicotyledons. The layers formed 
in such exceptional instances as Yucca, Dracaena, and analogous stems are totally diflfer- 
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