254 
Boodle and W or s dell. — On the 
elements, where the spiral lines were much fainter and much 
closer together, they did not give this appearance, and in 
such cases it was not easy to say what they really were. 
Similar spiral lines were also noticed in the tracheides of 
Podocarpus and Phyllocladus . Also the bordered pits of the 
elements in the node differed from those in the internode in 
the fact that their openings were much wider and more 
slit-like. 
In examining a young stem of Ephedra in which the 
bundles were still separated by parenchyma, transfusion-tissue 
was observed in the medullary ray, connecting the xylem of 
the bundle with the innermost cells of the palisade-tissue. 
They were tracheides, possessing both reticulate thickenings 
and bordered pits, and had no contents. They were scattered 
promiscuously amongst the parenchyma-cells, whose shape 
they still retained for the most part, though some were 
considerably more elongated longitudinally. Sometimes an 
uninterrupted row of them extended down through the tissue. 
They were elements somewhat of the same nature as those 
forming the protoxylem of Gnetum and Ephedra , and it is 
the same type of tissue, though better developed, as occurs 
on either side of the bundle in the leaf of Ephedra (Fig. 42). 
In conclusion, it may be pointed out that Ephedra and 
Casuarina both have rudimentary leaves, assimilating stems, 
and transfusion-tissue ; but while the transfusion-tissue of 
Ephedra has bordered pits, that of Casuarina has only simple 
pits. This may mean that the transfusion-tissue of Casuarina 
is only a recent transformation of ordinary parenchyma. 
Again, the structure of Gnetum panicidaium , described 
above, might be interpreted as showing a tendency to repro- 
duce an ancestral type of structure at the node ; especially 
when compared with the nodal structure (cambium) described 
by Cormack 1 in Equisetum . It must, however, be re- 
membered that the requirements for the conduction of water 
at the node, as also the mechanical conditions there, are no 
1 Cormack, Annals of Botany, 1893. 
