in the Genus Primula. 
325 
Fig. 6. Primula japonica ; transverse section of the median leaf-trace in the 
petiole. The stele is here quite perfect, having passed through a stage similar 
to Fig. 5 lower down in the petiole, x 90. 
Fig. 7. Primula japonica ; transverse section of central cylinder of a seedling. 
The leaf-trace departs in a normal manner, leaving the stele intact, x 100. 
Figs. 8 and 9. Primula involucrata ; transverse sections of central cylinder of 
a seedling. The leaf-trace departs in such a manner as to leave an internal 
endodermis. (JP. japonica also makes use of this method of transition.) Fig. 8, 
the endodermis is invaginated through the leaf-gap. x 70. Fig. 9, the leaf-gap 
becomes closed in such a manner as to include a portion of the endodermis which 
becomes internal, x 100. 
Fig. 10. Primula japonica', diagrammatic longitudinal section through the central 
cylinder of a seedling. The endodermis passes into the interior of the stele 
through the leaf-gaps. The dark regions indicate xylem ; the light, phloem ; and 
the dotted line, endodermis. 
Fig. 11. Primula involucrata ; transverse section of the central cylinder of 
a seedling after the departure of one of the earlier leaf-traces. The stele is still 
intact, x 100. 
Figs. 12-14. Transverse sections of the same, showing how the stele eventually 
becomes broken up. 1 . t? the eighth leaf-trace ; /. t. s the ninth leaf-trace ; l.g} the 
seventh leaf-gap ; l. gP the eighth leaf-gap. Fig. 12 shows the invagination of the 
endodermis through the seventh leaf-gap. x 100. Fig. 13 shows that the seventh 
leaf-gap is still open, while the eighth leaf-gap is almost free ; its final departure 
will break up the stele into two portions. X70. Fig. 14, the two portions are 
fused across the seventh leaf-gap, the eighth leaf-gap is still open, and the ninth 
leaf-trace is about to pass off. x 90. 
