2 34 
Boodle and Worsdell. — On the 
position founded on anatomical characters. His descriptions 
of the tissues are, however, very general. Like others before 
him, he comes to the conclusion that the structure of Casuarina 
is isolated among the Apetalae, and perhaps among Dicotyle- 
dons. He places it nearest to Proteaceae. 
The general character of the young stem of Casuarina 
is sufficiently well known ; so that we need only shortly 
mention, that the young branches are the chief assimilating 
organs of the plant ; this assimilating function they carry on 
by means of the characteristic ridges which run in a longi- 
tudinal direction down the stem, and have been described as 
adherent portions of the rudimentary scale-like leaves, which 
are arranged in whorls at intervals on the stem. 
Anatomy of Young Stem. 
The transverse section of the young stem of Casuarina, as 
seen in Plate XV, Fig. 1, shows a number of prominent ridges, 
varying in number and shape according to the species. They 
are separated from one another by furrows, which also in 
their form offer considerable variation. Poisson 1 describes 
another division of Casuarina , — Tetragonae, — in which de- 
pressions or furrows are absent ; but in the species described 
by him the position where the furrows would ordinarily occur 
is indicated by a tissue of colourless cells separating the 
palisade-tissue of each corner ; we find however, in another 
species, C. Rumphiana , Miq., described by Lecomte 2 , the 
palisade-tissue forms a continuous layer round the stem. 
The ridges are covered with a rather small-celled epidermis, 
having a thick outer wall in which small, refractive, roundish 
bodies are embedded : they lie in pocket-like depressions, and 
are arranged in fairly regular longitudinal rows on the stem. 
On the sides of the ridges, in the furrows, transversely-placed 
stomata occur ; they belong each to a longitudinal row 
running down the stem. A tuft of hairs, each usually con- 
1 Loc. cit v p. 103. 
2 Loc. cit., p. 314. 
