Comparative Anatomy of the Casuarineae. 237 
In a radial longitudinal section of a young stem, passing 
through the median line of one of the small leaf-teeth, one 
notices a layer of palisade-cells on its outer or dorsal side, 
which stops short at a little distance from the apex. On the 
inner side of this tissue there is a small bundle. The leaf- 
teeth are ‘ fused 5 below to form a short sheath, closely applied 
to the stem, this structure being precisely analogous to that of 
a gamopetalous corolla ending in a number of free segments 
(Fig. 7). Each leaf-tooth is continued downwards into a 
prominent ridge which extends to the next node below. 
This structure is regarded by various authors as an adherent 
leaf, Loew giving it the special name of ‘ phyllichnium,’ while 
Lecomte prefers to call it simply a leaf. 
In a longitudinal section made through one of these ridges, 
the transfusion-tracheides described above as occurring on the 
edge of the cortical bundle, are easily distinguished. In 
longitudinal section the character and function of these 
elements is much more clearly seen than in the transverse 
section. Owing to their position and the course they take, 
which is usually in an obliquely-ascending direction from the 
xylem of the bundle to the palisade-tissue, they appear to 
best advantage in a section which is not quite radial. In such 
a section they are sometimes seen in connexion with the 
bundle, sometimes quite isolated. A good example of the 
former case, as illustrating their function and relative position, 
was seen in a section which showed two spiral elements of 
the xylem of the bundle ; running out from these elements, 
among the parenchyma-cells, was an extremely narrow, 
elongated tracheide, bent outward in its middle, and at its 
extremities abutting on the spiral tracheides of the bundle. 
Where this element bent outward it was in conjunction with 
another similar tracheide which took a more or less sinuous, 
longitudinal course down the side of the innermost cells of 
the assimilating tissue. Directly opposite the point where these 
two narrow tracheides were in contact, and separated from 
them by a single layer of cells, was a vertical row of four 
parenchyma-shaped transfusion-elements (Fig. 8, tf). As 
