Centripetal Xylem in Equisetnm . 601 
Fig. 5. Equisetum maximum ; radial section through vegetative leaf-trace as it leaves the 
cortex, x 500. 
Fig. 6 . Equisetum hyemale ; radial section through an axial bundle of the cone, x 500. 
Fig. 7. Equisetum maximum ; transverse section of sporophyll-trace. x 1100. 
Fig. 8. Equisetum Jiuviatile ; transverse section of sporophyll-trace. x 1100. 
Fig. 9. The same ; longitudinal section of sporophyll-trace. x 500. 
Fig. 10. Equisetum maximum', longitudinal section of the sporophyll-trace, showing forking 
at base of scute and the mesarch structure of the branch-bundles, x 180. 
Fig. 11. Equisetum arvense\ longitudinal section of sporophyll-trace. x 500. 
Fig. 12. Equisetutn palustre ; longitudinal section of sporophyll-trace. x 500. 
