Knowledge of Rachiopteris cylindrica , Will. 565 
Fig. 8. A /3 stem just above dichotomy of the stele; each branch has only one protoxylem 
group. A root r is passing through the cortex; the crushed outer cortex is indicated at several 
points, x 32. (From Q 105, Cash collection.) 
Fig. 9. A jS stem preparing for dichotomy, immediately above the level of leaf-trace production. 
The middle cortex is much crushed, x 58. (From K 21 University College, London.) 
PLATE XXVII. 
Rachiopteris cylindrica. 
Fig. 1. The adaxial margin of the bundle in an a petiole just above the separation of the latter 
from the stem. The anterior metaxylem appears to be breaking down, and the protoxylem is 
indefinite. Note the crushed phloem cells ( ph .), and the transverse section of the pits (pt.) on the 
tracheide walls, x 40. (From slide 302.6 in Dr. Gordon’s collection.) 
Fig. 2. A petiolar bundle passing through the cortex of a fi stem. Note the single protoxylem 
group, and the imperfectly-lignified metaxylem. x 200. (From K 21 r, University College, 
London.) 
Fig. 3. The stele of a diarch root, showing the pitted appearance of the endodermis. Certain 
of the cells appear to be less resistant than the others ; note particularly a cell a in the neighbourhood 
of one of the protoxylem groups, x 200. (From K 21 r, University College, London.) 
Fig. 4. A large a stem, showing the origin of two roots, x 40. (From 302-6, Dr. Gordon’s 
collection.) 
