APEX OF THE ROOT IN OSMUNDA AND TODEA. 103 
Todea barbara. — Figs. 23 — 29. 
Fig. 23. — Transverse section, showing an irregular arrangement of the 
meristem. 
Fig. 24.— A well-marked meristem in transverse section, showing four 
regular initial cells. 
Fig. 25. — Longitudinal section, showing two pyramidal initial cells. 
Fig. 26. — Lougitudinal section, with two oblong initial cells. 
Fig. 27. — Group of cells, derived by irregular division from one rhizogenic 
cell of the endodermis. 
Fig. 28. — The same, but the division in this case is regular ; two almost 
square initial cells. 
Fig. 29. — Apical group, from a rather older lateral root, showing two 
pyramidal initial cells. 
Angiopteris evecta. — Figs. 30 — 32. 
Fig. 30. — Transverse section of a main root, showing the mode of origin 
of a lateral root from one cell of the endodermis ( e . e.), also the xylem of the 
main root, and divisions in the pericambium ( p .) and cortex ( c .). In the cells 
derived by division from the rhizogenic cell, two (x) may be recognised as the 
initial cells. 
Fig. 31. — Group of cells of the lateral root, derived from a single rhizo- 
genic cell : the oblong initial cells marked (x). 
Fig. 32. — A section transverse to the axis of a very young lateral root, still 
embedded in the cortex of the main root. It shows the four initial cells (x) 
as described by Schwendener. 
Fig. 33. — Scheme of construction of the apex of a root with a three-sided 
pyramidal apical cell, quoted from Sachs’s * Arbeiten,’ Bd. ii, Taf. iv, fig. 12. 
Fig. 34. — Scheme of construction of a root of the Marattiaceous type. 
Fig. 35. — a. A small portion of the young cortex of the same root of 
Osmunda regaiis as is represented in Fig. 14. B. A small portion of the 
young cortex of Todea barbara. The arrows point towards the apex of 
the roots. 
