1091 
Relationships of the G net ales. 
fibres. In fact, de Bary 1 concluded that they fell naturally into this cate- 
gory. It should be noted, however, that the Angiospermic fibrous cells, as 
their name indicates, resemble the woody fibres rather than tracheides. 
They are much longer and have thicker walls. Although the lack of septa is 
common to the two, it is doubtful whether they are homologous structures. 
4. Wood Rays. 
The ray structure of Ephedra has hitherto been passed over with the 
simple statement of Strasburger 2 that they are multiseriate. In reality the 
conditions which they present are no less significant from an evolutionary 
point of view than those of the vessels to which the whole attention has 
been devoted in the past. The fact that they are multiseriate is in itself of 
supreme importance, for in connexion with other facts it emphasizes their 
close relationship to those of the Dicotyledones. 
The multiseriate condition is shown in transverse section in PI. XCIV, 
Fig. 10 at the left and in tangential section in PI. XCV, P"ig. 13. The 
number of rows of cells varies from one to ten, but the average number is 
four or five. There is considerable specific and regional variation in this 
respect. In tangential section they are found in most cases to be solid 
homogeneous masses which extend vertically to considerable heights. They 
are not so high, however, as those of the Oak, but have a more fusiform 
outline (PL XCVI, Fig. 3a). 
The individual cells are extremely variable in size and shape. They 
may be isodiametric or elongated radially or vertically. As these varia- 
tions may be found within a small area, they give the ray a peculiarly 
irregular appearance, as is shown in Fig. 26, and especially in PI. XCV, 
Fig. 13. Furthermore, in old wood, all the cells of the marginal rows often 
become elongated obliquely to the course of the ray, a condition which no 
doubt results from the slow growth of the ray in comparison to that 
of the surrounding wood. 
Each cell is strongly lignified, resembling in this respect the ray cells 
of Conifers and Dicotyledones and differing from those of the Cycads and 
Bennettitales. The simple pits, like those of the Dicotyledones, occur 
on all walls and are very small, being merely fine pores. Their character 
may be distinguished in PI. XCVI, Fig. 26, especially at the top of the 
field. All these features give an appearance in radial section strikingly like 
that of a large ray of the Dicotyledones. 
The conditions of the rays in the young stem are quite different from 
those just described for the adult. At the pith one finds only uniseriate 
rays similar to those which are characteristic of the Conifers (Figs. 27 and 
29). From this condition the broad ray of the adult is produced in two 
1 Comparative Anatomy of Phanerogams and Ferns, 
2 fiber den Bau, &c. 
